Dr. Susan Knox specializes in the treatment of breast cancer and melanoma, and sees a variety of general radiation oncology patients. She has practiced as a radiation oncologist for more than 25 years.
A primary area of research in Dr. Knox’s laboratory is the study of novel therapies (targeted therapies, radiosensitizers, radioprotectors, and biological response modifiers) for the treatment of solid tumors, with a particular focus on prostate cancer, breast cancer and melanoma, using small animal tumor models. Her research is interdisciplinary and spans the study of mechanisms of action at the molecular level to translational studies and early clinical trials. Her drug discovery/development work, and research on innovative therapeutic approaches has resulted in 3 new ongoing clinical trials. A major focus of both her laboratory and clinical research is the use of radiation as a component of in situ tumor vaccine strategies. She has had a long -standing interest in clinical research and has served as a PI on numerous clinical trials and as a member of the Clinical Oncology Study Section. As the Faculty Director of the PRMS for the Stanford Cancer Institute, she oversees the Scientific Review Committee and chairs the Data and Safety Monitoring Committee.
- Cancer > Cutaneous (Dermatologic) Oncology
- Cancer > Lymphoma
- Cancer > Radiation Oncology
- Radiation Oncology
- Radiation Therapy
- Lymphoma, Transplantation, Breast Cancer, Targeted Therapies
Program Evaluation Committee Member, Department of Radiation Oncology (2014 - Present)
Working Group Member, Society of Nuclear Medicine and Molecular Imaging (2014 - Present)
Committee Member, Stanford University on Health and Safety (2013 - 2016)
Executive Committee Member: Cancer Clinical Trials Office, Stanford Cancer Center (2011 - Present)
Executive Committee Member: Clinical Research Onsight Group, Stanford Cancer Center (2011 - Present)
Department Representative, School of Medicine Faculty Senate (2011 - 2016)
Committee Member, SAMFUND Selection Committee (2010 - Present)
Committee Member, SPARK Committee (2009 - Present)
BioX Program Member, Stanford University (2008 - Present)
Lymphoma Disease Management Group Member, Stanford Cancer Center (2008 - Present)
The Molecular Therapeutics Program, Stanford Cancer Center (2008 - Present)
Committee Member, Committee on Professionalism, Performance and Promotion (2007 - Present)
Committee on the State of Science in Nuclear Medicine, Subcommittee on Targeted Radiotherapy, The National Academies (2006 - Present)
Advisory Board and Training Committee, NIH T32 SCIT CA09695 (2005 - Present)
Medical Education Leadership Group, Stanford Cancer Center (2005 - Present)
President, Alumni Association, Stanford School of Medicine (2005 - 2007)
Director, Core: Protocol Review and Monitoring System, Stanford Cancer Center (2004 - Present)
Chair, Data and Safety Monitoring Committee, Stanford Clinical Trials Office, Cancer Center (2003 - Present)
Executive Committee, Clinical Cancer Center (2003 - Present)
Associate Editor, Journal of Clinical Oncology (2003 - 2006)
Assistant Dean for Medical Student Advising, Stanford University School of Medicine (2002 - Present)
Member, Clinical Oncology Study Section (2001 - 2004)
Board of Governers, Stanford Medical Alumni Association (2000 - 2007)
Associate Editor, Radiation Research (2000 - 2003)
Editorial Board Member, Cancer Biotherapy and Radiopharmaceuticals (1996 - Present)
Honors & Awards
President, Alumni Association, Stanford University School of Medicine (2005-2007)
Elected Councilor Medicine, Radiation Research Society (2003)
Charles F. Kettering Selection Committee, General Motors Cancer Research Foundation (2000-2002)
Board of Governors, Stanford Medical Alumni Association (2000-2008)
Lazard Faculty Scholar, Lazard Faculty (1992-93)
Clinical Oncology Career Development Award, American Cancer Society (1991-94)
Leadership in Education, Stanford University School of Medicine (2008)
Residency:Stanford University School of Medicine Registrar (1990) CA
Fellowship:Stanford University School of Medicine Registrar (1989) CA
Internship:UC Davis Medical Center (1986) CA
Medical Education:Stanford University School of Medicine (1985) CA
Post Doc Fellow, Stanford Univ. Hospital, Medical Oncology (1989)
Medical Intern, UC Davis, California (1986)
Post-Doc Fellow/Res. Assist., Stanford Univ. Hospital, Medical Oncology (1989)
MD, Stanford University (1985)
Post-Doc Res. Immunologist, UC Davis, California, Energy-Related Health Research
PhD, UC Davis, California (1980)
AB, UC Berkeley, California, (1974)
Current Research and Scholarly Interests
- Radioimmunotherapy (RIT) and Systemically Targeted Radiation Therapy
- Low Dose Rate Effects
- Radioprotective Agents, Growth Factors/Receptors
- Oncogenes, Apoptosis & Radiosensitivity
- Apoptosis and Signal Transduction Pathways
- Effects of Radiation on the Immune Response
- Biological Response Modifiers and Novel Targeted Radiosensitizers
- Non-Hodgkin's Lymphomas
- Mycosis Fungoides
- Breast and Prostate Cancer
- Radiation as a component of Tumor Vaccine Strategies
Independent Studies (8)
- Directed Reading in Cancer Biology
CBIO 299 (Aut, Sum)
- Directed Reading in Radiation Oncology
RADO 299 (Aut, Win, Spr, Sum)
- Early Clinical Experience in Radiation Oncology
RADO 280 (Aut, Win, Spr, Sum)
- Graduate Research
CBIO 399 (Aut, Sum)
- Graduate Research
RADO 399 (Aut, Win, Spr, Sum)
- Medical Scholars Research
RADO 370 (Aut, Win, Spr, Sum)
- Readings in Radiation Biology
RADO 101 (Aut, Win, Spr, Sum)
- Undergraduate Research
RADO 199 (Aut, Win, Spr, Sum)
- Directed Reading in Cancer Biology
Academic Advising Dean
Fahed Ayoub, Pamela Basto, Winston Becker, James Chen, Thomas Chew, Adam Daoud, Michelle Drews, Kyle Eagen, Cordelia Erickson-Davis, Ryan Flynn, Trit Garg, Michelle Han, Joy He, Mark Jeng, Lori Lee, Emily Liu, Yufei Liu, Lance Middleton, Mateen Moghbel, Tara Mokhtari, Michelle Nguyen, Nancy Nkansah-Mahaney, Justin Norden, Jaspreet Pannu, John Pluvinage, Tyler Prestwood, Julia Ransohoff, Anirudh Saraswathula, Zahra Sayyid, Timothy Singer, Holly Stewart, Gerald Tiu
A Prospective Clinical Trial Combining Radiation Therapy With Systemic Immunotherapy in Metastatic Melanoma.
International journal of radiation oncology, biology, physics
2016; 96 (3): 578-588
Local radiation therapy (RT) combined with systemic anti-cytotoxic T-lymphocyte-associated protein-4 immunotherapy may enhance induction of systemic antimelanoma immune responses. The primary objective of the present trial was to assess the safety and efficacy of combining ipilimumab with RT in patients with stage IV melanoma. The secondary objectives included laboratory assessment of induction of antimelanoma immune responses.In our prospective clinical trial, 22 patients with stage IV melanoma were treated with palliative RT and ipilimumab for 4 cycles. RT to 1 to 2 disease sites was initiated within 5 days after starting ipilimumab. Patients had ≥1 nonirradiated metastasis measuring ≥1.5 cm available for response assessment. Tumor imaging studies were obtained at baseline, 2 to 4 weeks after cycle 4 of ipilimumab, and every 3 months until progression. Laboratory immune response parameters were measured before and during treatment.Combination therapy was well-tolerated without unexpected toxicities. Eleven patients (50.0%) experienced clinical benefit from therapy, including complete and partial responses and stable disease at median follow-up of 55 weeks. Three patients (27.3%) achieved an ongoing systemic complete response at a median follow-up of 55 weeks (range 32-65), and 3 (27.3%) had an initial partial response for a median of 40 weeks. Analysis of immune response data suggested a relationship between elevated CD8-activated T-cells and response.This is the second prospective clinical trial of treatment of metastatic melanoma using the combination of RT and systemic immunotherapy and the first using this sequence of therapy. The results from the present trial demonstrate that a subset of patients may benefit from combination therapy, arguing for continued clinical investigation of the use of RT combined with immunotherapy, including programmed cell death 1 inhibitors, which might have the potential to be even more effective in combination with RT.
View details for DOI 10.1016/j.ijrobp.2016.07.005
View details for PubMedID 27681753
RRx-001, A novel dinitroazetidine radiosensitizer
INVESTIGATIONAL NEW DRUGS
2016; 34 (3): 371-377
The 'holy grail' in radiation oncology is to improve the outcome of radiation therapy (RT) with a radiosensitizer-a systemic chemical/biochemical agent that additively or synergistically sensitizes tumor cells to radiation in the absence of significant toxicity. Similar to the oxygen effect, in which DNA bases modified by reactive oxygen species prevent repair of the cellular radiation damage, these compounds in general magnify free radical formation, leading to the permanent "fixation" of the resultant chemical change in the DNA structure. The purpose of this review is to present the origin story of the radiosensitizer, RRx-001, which emerged from the aerospace industry. The activity of RRx-001 as a chemosensitizer in multiple tumor types and disease states including malaria, hemorrhagic shock and sickle cell anemia, are the subject of future reviews.
View details for DOI 10.1007/s10637-016-0326-y
View details for Web of Science ID 000376129000012
View details for PubMedID 26841903
View details for PubMedCentralID PMC4859863
Whole Brain Radiotherapy and RRx-001: Two Partial Responses in Radioresistant Melanoma Brain Metastases from a Phase I/II Clinical Trial: A TITE-CRM Phase I/II Clinical Trial.
2016; 9 (2): 108-113
Kim et al. report two patients with melanoma metastases to the brain that responded to treatment with RRx-001 and whole brain radiotherapy (WBRT) without neurologic or systemic toxicity in the context of a phase I/II clinical trial. RRx-001 is an reactive oxygen and reactive nitrogen species (ROS/RNS)-dependent systemically nontoxic hypoxic cell radiosensitizer with vascular normalizing properties under investigation in patients with various solid tumors including those with brain metastases.Metastatic melanoma to the brain is historically associated with poor outcomes and a median survival of 4 to 5 months. WBRT is a mainstay of treatment for patients with multiple brain metastases, but no significant therapeutic advances for these patients have been described in the literature. To date, candidate radiosensitizing agents have failed to demonstrate a survival benefit in patients with brain metastases, and in particular, no agent has demonstrated improved outcome in patients with metastatic melanoma. Kim et al. report two patients with melanoma metastases to the brain that responded to treatment with novel radiosensitizing agent RRx-001 and WBRT without neurologic or systemic toxicity in the context of a phase I/II clinical trial.
View details for DOI 10.1016/j.tranon.2015.12.003
View details for PubMedID 27084426
View details for PubMedCentralID PMC4833892
Rockets, Radiosensitizers, and RRx-001: An Origin Story Part I
2016; 115: 173-180
View details for Web of Science ID 000376406200003
Rockets, radiosensitizers, and RRx-001: an origin story part I.
2016; 21 (115): 173-180
From Adam and Eve, to Darwinism, origin stories attempt to fill in the blanks, connect the dots, and define the turning points that are fundamental to subsequent developments. The purpose of this review is to present the origin story of a one-of-a-kind anticancer agent, RRx-001, which emerged from the aerospace industry as a putative radiosensitizer; not since the dynamite-to-dilator transformation of nitroglycerin in 1878 or the post-World War II explosive-to-elixir conversion of hydralazine, an ingredient in rocket fuel, to an antihypertensive, an antidepressant and an antituberculant, has energetic chemistry been harnessed for therapeutic purposes. This is Part 1 of the radiosensitization story; Parts 2 and 3, which detail the crossover activity of RRx-001 as a chemosensitizer in multiple tumor types and disease states including malaria, hemorrhagic shock and sickle cell anemia, are the subject of future reviews.
View details for PubMedID 27115167
Epigenetic effects of RRx-001: a possible unifying mechanism of anticancer activity.
2015; 6 (41): 43172-43181
RRx-001 is a novel aerospace-derived compound currently under investigation in several ongoing Phase II studies. In a Phase I trial, it demonstrated anti-cancer activity and evidence of resensitization to formerly effective therapies in heavily pre-treated patients with relapsed/refractory solid tumors. RRx-001 generates reactive oxygen and nitrogen species (ROS and RNS) and nitric oxide (NO), elicits changes in intracellular redox status, modulates tumor blood flow, hypoxia and vascular function and triggers apoptosis in cancer cells. We investigated the effect of RRx-001 on the epigenome of SCC VII cancer cells. RRx-001 at 0.5 and 2 μM significantly decreased global DNA methylation, i.e., 5-methylcytosine levels, in SCC VII cells. Consistently, 0.5-5 μM RRx-001 significantly decreased Dnmt1 and Dnmt3a protein expression in a dose- and time-dependent manner. In addition, global methylation profiling identified differentially methylated genes in SCC VII cells treated with 0.5, 2, and 5 μM RRx-001 compared to control cells. Twenty-three target sites were hypomethylated and 22 hypermethylated by >10% in the presence of at least two different concentrations of RRx-001. Moreover, RRx-001 at 2 μM significantly increased global acetylated histone H3 and H4 levels in SCC VII cells after 24 hour treatment, suggesting that RRx-001 regulates global acetylation in cancer cells. These results demonstrate that, in contrast to the traditional "one drug one target" paradigm, RRx-001 has multi(epi)target features, which contribute to its anti-cancer activity and may rationalize the resensitization to previously effective therapies observed in clinical trials and serve as a unifying mechanism for its anticancer activity.
View details for DOI 10.18632/oncotarget.6526
View details for PubMedID 26657731
View details for PubMedCentralID PMC4791224
- NO to cancer: The complex and multifaceted role of nitric oxide and the epigenetic nitric oxide donor, RRx-001 REDOX BIOLOGY 2015; 6: 1-8
Safety and activity of RRx-001 in patients with advanced cancer: a first-in-human, open-label, dose-escalation phase 1 study
2015; 16 (9): 1133-1142
Epigenetic alterations have been strongly associated with tumour formation and resistance to chemotherapeutic drugs, and epigenetic modifications are an attractive target in cancer research. RRx-001 is activated by hypoxia and induces the generation of reactive oxygen and nitrogen species that can epigenetically modulate DNA methylation, histone deacetylation, and lysine demethylation. The aim of this phase 1 study was to assess the safety, tolerability, and pharmacokinetics of RRx-001.In this open-label, dose-escalation, phase 1 study, we recruited adult patients (aged >18 years) with histologically or cytologically confirmed diagnosis of advanced, malignant, incurable solid tumours from University of California at San Diego, CA, USA, and Sarah Cannon Research Institute, Nashville, TN, USA. Key eligibility criteria included evaluable disease, Eastern Cooperative Group performance status of 2 or less, an estimated life expectancy of at least 12 weeks, adequate laboratory parameters, discontinuation of all previous antineoplastic therapies at least 6 weeks before intervention, and no residual side-effects from previous therapies. Patients were assigned to receive intravenous infusions of RRx-001 at increasing doses (10 mg/m(2), 16·7 mg/m(2), 24·6 mg/m(2), 33 mg/m(2), 55 mg/m(2), and 83 mg/m(2)) either once or twice-weekly for at least 4 weeks, with at least three patients per dose cohort and allowing a 2-week observation period before dose escalation. Samples for safety and pharmacokinetics analysis, including standard chemistry and haematological panels, were taken on each treatment day. The primary objective was to assess safety, tolerability, and dose-limiting toxic effects of RRx-001, to determine single-dose pharmacokinetics, and to identify a recommended dose for phase 2 trials. All analyses were done per protocol. Accrual is complete and follow-up is still on-going. This trial is registered with ClinicalTrials.gov, number NCT01359982.Between Oct 10, 2011, and March 18, 2013, we enrolled 25 patients and treated six patients in the 10 mg/m(2) cohort, three patients in the 16·7 mg/m(2) cohort, three patients in the 24·6 mg/m(2) cohort, four patients in the 33 mg/m(2) cohort, three patients in the 55 mg/m(2), and six patients in the 83 mg/m(2) cohort. Pain at the injection site, mostly grade 1 and grade 2, was the most common adverse event related to treatment, experienced by 21 (84%) patients. Other common drug-related adverse events included arm swelling or oedema (eight [32%] patients), and vein hardening (seven [28%] patients). No dose-limiting toxicities were observed. Time constraints related to management of infusion pain from RRx-001 resulted in a maximally feasible dose of 83 mg/m(2). Of the 21 evaluable patients, one (5%) patient had a partial response, 14 (67%) patients had stable disease, and six (29%) patients had progressive disease; all responses were across a variety of tumour types. Four patients who had received RRx-001 were subsequently rechallenged with a treatment that they had become refractory to; all four responded to the rechallenge.RRx-001 is a well-tolerated novel compound without clinically significant toxic effects at the tested doses. Preliminary evidence of activity is promising and, on the basis of all findings, a dose of 16·7 mg/m(2) was recommended as the targeted dose for phase 2 trials.EpicentRx (formerly RadioRx).
View details for DOI 10.1016/S1470-2045(15)00089-3
View details for Web of Science ID 000363966100055
View details for PubMedID 26296952
Nrf2 activity as a potential biomarker for the pan-epigenetic anticancer agent, RRx-001.
2015; 6 (25): 21547-21556
Nuclear factor erythroid 2-related factor 2 (Nrf2) is a master regulatory transcription factor that plays an important role in the antioxidant response pathway against anticancer drug-induced cytotoxic effects. RRx-001 is a new anticancer agent that generates reactive oxygen and nitrogen species, and leads to epigenetic alterations in cancer cells. Here we report the RRx-001 mediated nuclear translocation of Nrf2 and the activation of expression of its downstream enzymes HO-1 and NQO1 in tumor cells. Inhibition of intrinsic Nrf2 expression by Nrf2-specific siRNA increased cell sensitivity to RRx-001. Molecular imaging of tumor cells co-expressing pARE-Firefly luciferase and pCMV-Renilla luciferase-mRFP in vitro and in vivo in mice revealed that RRx-001 significantly increased ARE-FLUC signal in cells in a dose- and time-dependent manner, suggesting that RRx-001 is an effective activator of the Nrf2-ARE signaling pathway. The pre-treatment level of ARE-FLUC signal in cells, reflecting basal activity of Nrf2, negatively correlated with the tumor response to RRx-001. The results support the concept that RRx-001 activates Nrf2-ARE antioxidant signaling pathways in tumor cells. Hence measurement of Nrf2-mediated activation of downstream target genes through ARE signaling may constitute a useful molecular biomarker for the early prediction of response to RRx-001 treatment, and thereby guide therapeutic decision-making.
View details for PubMedID 26280276
The Development Of RRx-001, A Novel Nitric-Oxide-Mediated Epigenetically Active Anticancer Agent.
2015; 5: 422-?
RRx-001 is a novel NO and hypoxia mediated anticancer agent with epigenetic activity. In the first-in-human, Phase I trial, 5/5 patients who progressed on RRx-001 treatment were resensitized to previously refractory therapy, hinting at a generalized resensitization effect.A randomized open-label multi-part, multi-center phase II trial of RRx-001 versus regorafenib (ROCKET) has commenced to explore the resensitization and/or 'episensitization' potential in irinotecan refractory tumors and its impact on overall survival.Patients with irinotecan-refractory metastatic colorectal cancer with an ECOG PS 0-1 who progressed on oxaliplatin-, and irinotecan-based regimens with or without bevacizumab, cetuximab or panitumumab are randomized 2:1 to receive RRx-001 16.5mg/m(2) IV 1x/week or regorafenib 160mg orally 21 of 28 days until progression or unacceptable toxicity followed by treatment with refractory irinotecan-based therapies.To date, 26 patients have been randomized with 18 patients evaluable for resensitization. Post RRx-001 patients demonstrated marked decreases in CEA in 12/13 patients as compared to 5 patients receiving regorafenib who were too systemically unwell to proceed to subsequent treatment. Progression free survival (ongoing) for RRx-001+irinotecan is 4.9 months compared 1.8 months on Regorafenib+irinotecan.Early results in the ROCKET study suggest that RRx-001-mediated resensitization to previously refractory therapies may have a generalized effect, independent of KRAS or p53 status. These early results are intriguing, suggesting improved QOL and overall survival over currently approved therapy in the chemotherapy refractory colorectal cancer.
View details for DOI 10.1016/j.redox.2015.09.035
View details for PubMedID 28162292
Predictors of clinical response to immunotherapy with or without radiotherapy.
Journal of radiation oncology
2015; 4: 339-345
Success with recent immunotherapies has resulted in previously unattainable response rates, as well as durable responses in diseases with historically poor prognoses. The combination of radiation therapy and immunotherapy has been a recent area of active investigation, with exciting results in a subset of patients. However, patient characteristics predictive of probable benefit from therapy and clinically meaningful biomarkers indicative of the early development of an antitumor immune response have yet to be identified. What is needed is a better way to predict which patients are likely to benefit from therapy, which would allow those patients unlikely to benefit from immunotherapy to be spared potentially futile therapies, thereby avoiding unnecessary risks of toxicity and costly treatment. Here, we summarize the early data on predictors of clinical response to immunotherapy, and to immunotherapy in combination with radiation.
View details for PubMedID 26709361
Immunotherapy and radiation.
Seminars in oncology
2014; 41 (6): 702-713
Radiation therapy and immunotherapy are both well-established treatments for malignant disease. Radiotherapy has long been utilized for purposes of providing local tumor control, and the recent success with novel immunomodulatory agents has brought immunotherapy into the forefront of clinical practice for the treatment of many tumor types. Although radiotherapy has traditionally been thought to mediate tumor regression through direct cytotoxic effects, it is now known that radiation also alters the local tumor microenvironment with effects on both the local and systemic anti-tumor immune response. There is growing evidence that the rational integration of the immunomodulatory effects of radiotherapy with the expanding armamentarium of clinically approved immunotherapeutics can yield potent anti-tumor responses exceeding the benefit of either therapy alone. Here we summarize current approaches to the combination of immunotherapy with radiation therapy.
View details for DOI 10.1053/j.seminoncol.2014.09.019
View details for PubMedID 25499631
- Novel Human Radiation Exposure Biomarker Panel Applicable for Population Triage INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS 2014; 90 (3): 612-619
The Implications of Hyponitroxia in Cancer
2014; 7 (2): 167-173
Tumors are spatially heterogeneous, with regions of relative hypoxia and normoxia. The tumor microenvironment is an important determinant of both tumor growth and response to a variety of cytotoxic and targeted therapies. In the tumor microenvironment, reactive oxygen species and nitric oxide (NO) are important mediators of the level of expression of many transcription factors and signaling cascades that affect tumor growth and responses to therapy. The primary objective of this review is to explore and discuss the seemingly dichotomous actions of NO in cancer biology as both a tumor promoter and suppressor with an emphasis on understanding the role of persistently low NO concentrations or hyponitroxia as a key mediator in tumor progression. This review will also discuss the potential role of hyponitroxia as a novel therapeutic target to treat cancer and outline an approach that provides new opportunities for pharmacological intervention.
View details for DOI 10.1016/j.tranon.2014.02.001
View details for Web of Science ID 000342685500001
View details for PubMedID 24731473
View details for PubMedCentralID PMC4101386
- The implications of hyponitroxia in cancer Translational Oncology 2014; 7 (2): 167-173
Two Case Reports of Resensitization to Previous Chemotherapy with the Novel Hypoxia-Activated Hypomethylating Anticancer Agent RRx-001 in Metastatic Colorectal Cancer Patients.
Case reports in oncology
2014; 7 (1): 79-85
The development of chemoresistance is a persistent problem during the treatment of cancer. Although reversion or modification of acquired chemoresistance has been previously observed, no systematic exploration has been undertaken. Here, we report a case study of 2 male patients, 62 and 66 years old, both with histologically proven, radiologically progressing, extensively pretreated, metastatic and refractory (≥2 conventional regimens and drug therapy) colorectal adenocarcinoma that was previously treated with FOLFIRI. The patients were resensitized to FOLFIRI after exposure to RRx-001 in the context of a phase-1 study. RRx-001 is a novel, hypomethylating and free-radical-inducing anticancer agent that activates nitrite reduction to NO under hypoxia and has an impact on epigenetic pathways. The repression of DNA methyltransferase 1 by RRx-001 may lead to demethylation and reexpression of silenced tumor suppressor genes, leading to resensitization. These examples provide insight into a nascent strategy to improve the prognosis in heavily pretreated cancer patients and suggest routes for further exploration.
View details for DOI 10.1159/000358382
View details for PubMedID 24575021
View details for PubMedCentralID PMC3934615
Episensitization: Therapeutic Tumor Resensitization by Epigenetic Agents: A Review and Reassessment
ANTI-CANCER AGENTS IN MEDICINAL CHEMISTRY
2014; 14 (8): 1121-1127
Resistance to chemotherapy, biological and targeted therapies is an important clinical problem. Resistance can arise and/or be selected for multiple mechanisms of action. Unfortunately, acquired resistance to antitumor agents or regimens is nearly inevitable in all patients with metastatic disease. Until recently, it was believed that this resistance was unalterable and irreversible, rendering retreatment with the same or similar drugs futile in most cases. However, the introduction of epigenetic therapies, including HDAC inhibitors and DNA methyltransferase inhibitors (DNMTIs), has provided oncologists with new strategies to potentially overcome this resistance. For example, if chemoresistance is the product of multiple non-genetic alterations, which develop and accumulate over time in response to treatment, then the ability to epigenetically modify the tumor to reconfigure it back to its baseline non-resistant state, holds tremendous promise for the treatment of advanced, metastatic cancer. This minireview aims (1) to explore the potential mechanisms by which a group of small molecule agents including HDACs (entinostat and vorinostat), DNA hypomethylating agents such as the DNMTIs (decitabine (DEC), 5-azacytidine (5-AZA)) and redox modulators (RRx-001) may reprogram the tumors from a refractory to non-refractory state, (2) highlight some recent findings in this area, and (3) discuss the therapeutic potential of resensitization approaches with formerly failed chemotherapies.
View details for Web of Science ID 000341885400008
View details for PubMedID 24893730
View details for PubMedCentralID PMC4262965
- Two Case Reports of Resensitization to Previous Chemotherapy with the Novel Hypoxia-Activated Hypomethylating Anticancer Agent RRx-001 in Metastatic Colorectal Cancer Patients Case Reports in Oncology 2014; 7 (1): 79-85
- Novel nitric oxide generating compound glycidyl nitrate enhances the therapeutic efficacy of chemotherapy and radiotherapy Biochemical and Biophysical Research Communications 2014; 447 (3): 537-542
Radioprotection and Cell Cycle Arrest of Intestinal Epithelial Cells by Darinaparsin, a Tumor Radiosensitizer
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
2013; 87 (5): 1179-1185
It was recently reported that the organic arsenic compound darinaparsin (DPS) is a cytotoxin and radiosensitizer of tumor cells in vitro and in subcutaneous xenograft tumors. Surprisingly, it was also found that DPS protects normal intestinal crypt epithelial cells (CECs) from clonogenic death after ionizing radiation (IR). Here we tested the DPS radiosensitizing effect in a clinically relevant model of prostate cancer and explored the radioprotective effect and mechanism of DPS on CECs.The radiation modification effect of DPS was tested in a mouse model of orthotopic xenograft prostate cancer and of IR-induced acute gastrointestinal syndrome. The effect of DPS on CEC DNA damage and DNA damage responses was determined by immunohistochemistry.In the mouse model of IR-induced gastrointestinal syndrome, DPS treatment before IR accelerated recovery from body weight loss and increased animal survival. DPS decreased post-IR DNA damage and cell death, suggesting that the radioprotective effect was mediated by enhanced DNA damage repair. Shortly after DPS injection, significant cell cycle arrest was observed in CECs at both G1/S and G2/M checkpoints, which was accompanied by the activation of cell cycle inhibitors p21 and growth arrest and DNA-damage-inducible protein 45 alpha (GADD45A). Further investigation revealed that DPS activated ataxia telangiectasia mutated (ATM), an important inducer of DNA damage repair and cell cycle arrest.DPS selectively radioprotected normal intestinal CECs and sensitized prostate cancer cells in a clinically relevant model. This effect may be, at least in part, mediated by DNA damage response activation and has the potential to significantly increase the therapeutic index of radiation therapy.
View details for DOI 10.1016/j.ijrobp.2013.08.051
View details for Web of Science ID 000327496600056
View details for PubMedID 24210080
Topical hypochlorite ameliorates NF-kappa B-mediated skin diseases in mice
JOURNAL OF CLINICAL INVESTIGATION
2013; 123 (12): 5361-5370
Nuclear factor-κB (NF-κB) regulates cellular responses to inflammation and aging, and alterations in NF-κB signaling underlie the pathogenesis of multiple human diseases. Effective clinical therapeutics targeting this pathway remain unavailable. In primary human keratinocytes, we found that hypochlorite (HOCl) reversibly inhibited the expression of CCL2 and SOD2, two NF-κB-dependent genes. In cultured cells, HOCl inhibited the activity of inhibitor of NF-κB kinase (IKK), a key regulator of NF-κB activation, by oxidizing cysteine residues Cys114 and Cys115. In NF-κB reporter mice, topical HOCl reduced LPS-induced NF-κB signaling in skin. We further evaluated topical HOCl use in two mouse models of NF-κB-driven epidermal disease. For mice with acute radiation dermatitis, topical HOCl inhibited the expression of NF-κB-dependent genes, decreased disease severity, and prevented skin ulceration. In aged mice, topical HOCl attenuated age-dependent production of p16INK4a and expression of the DNA repair gene Rad50. Additionally, skin of aged HOCl-treated mice acquired enhanced epidermal thickness and proliferation, comparable to skin in juvenile animals. These data suggest that topical HOCl reduces NF-κB-mediated epidermal pathology in radiation dermatitis and skin aging through IKK modulation and motivate the exploration of HOCl use for clinical aims.
View details for DOI 10.1172/JCI70895
View details for Web of Science ID 000327826100039
View details for PubMedID 24231355
Characterization of direct radiation-induced immune function and molecular signaling changes in an antigen presenting cell line
2013; 148 (1): 44-55
Radiation therapy is a widely used cancer treatment and pre-transplantation conditioning regimen that has the potential to influence anti-tumor and post-transplantation immune responses. Although conventionally fractionated radiation doses can suppress immune responses by depleting lymphocytes, single high doses of local tumor radiation can enhance immune responses. Using phospho-flow cytometry analysis of a human monocytic cell line, we identified novel radiation-induced changes in the phosphorylation state of NFκB family members known in other cell types to maintain and regulate immune function. These phosphorylation changes were p53 independent, but were strongly dependent upon ATM activation due to DNA damage. We found that radiation promotes the activation and APC functional maturation through phosphorylation of NFκB Essential Modulator (NEMO). Our results and the analytic methods are especially well suited to the study of functional changes in APC when radiation is used for immune modulation in clinical protocols.
View details for DOI 10.1016/j.clim.2013.03.008
View details for Web of Science ID 000320427300006
View details for PubMedID 23649044
Phase I Study of a Modified Regimen of (90)Yttrium-Ibritumomab Tiuxetan for Relapsed or Refractory Follicular or Transformed CD20+Non-Hodgkin Lymphoma
CANCER BIOTHERAPY AND RADIOPHARMACEUTICALS
2013; 28 (5): 370-379
Radioimmunotherapy capitalizes on the radiosensitivity of non-Hodgkin lymphoma (NHL) and the targeted nature of monoclonal antibodies. In an attempt to reverse bone marrow infiltration with B-cells and optimize the biodistribution of Yttrium-90 (⁹⁰Y)-ibritumomab tiuxetan, we conducted a phase I study combining a single course of ⁹⁰Y-ibritumomab tiuxetan after a 4-weekly course of rituximab in relapsed or refractory low-grade or transformed CD20+ B-cell NHLs with <25% marrow involvement. The 0.4 mCi/kg dose was associated with 80% grade-4 cytopenias. Dose escalation was held, and 6 patients were enrolled at a 0.3 mCi/kg cohort. As the 0.3 mCi/kg dose was well tolerated, the 0.4 mCi/kg cohort was expanded to 6 additional patients. In the expansion cohort, grade-4 cytopenia developed in 33%. Further dose escalation was held, and the maximum tolerated dose was determined at 0.4 mCi/kg. With this regimen, marrow involvement decreased in all patients with complete clearance in 50%. The overall response rate was 82%. With a median follow-up of 31.7 months, the median progression-free survival and time to next treatment were 12.3 and 10.9 months, respectively. Although this regimen was associated with a high response rate, the hematologic toxicity was higher than with the standard ⁹⁰Y-ibritumomab tiuxetan regimen.
View details for DOI 10.1089/cbr.2012.1387
View details for Web of Science ID 000320029500002
View details for PubMedID 23530878
Real time dynamic imaging and current targeted therapies in the war on cancer: a new paradigm.
2013; 3 (6): 437-447
In biology, as every science student is made to learn, ontology recapitulates phylogeny. In medicine, however, oncology recapitulates polemology, the science of warfare: The medical establishment is transitioning from highly toxic poisons that kill rapidly dividing normal and malignant cells with little specificity to tailored therapies that target the tumors with the lethality of the therapeutic warhead. From the advent of the information age with the incorporation of high-tech intelligence, reconnaissance, and surveillance has resulted in "data fusion" where a wide range of information collected in near real-time can be used to redesign most of the treatment strategies currently used in the clinic. The medical community has begun to transition from the 'black box' of tumor therapy based solely on the clinical response to the 'glass box' of dynamic imaging designed to bring transparency to the clinical battlefield during treatment, thereby informing the therapeutic decision to 'retreat or repeat'. The tumor microenvironment is dynamic, constantly changing in response to therapeutic intervention, and therefore the therapeutic assessment must map to this variable and ever-changing landscape with dynamic and non-static imaging capabilities. The path to personalized medicine will require incorporation and integration of dynamic imaging at the bedside into clinical practice for real-time, interactive assessment of response to targeted therapies. The application of advanced real time imaging techniques along with current molecularly targeted anticancer therapies which alter cellular homeostasis and microenvironment can enhance therapeutic interventions in cancer patients and further improve the current status in clinical management of patients with advanced cancers.
View details for DOI 10.7150/thno.5658
View details for PubMedID 23781290
View details for PubMedCentralID PMC3677414
- Topical hypochlorite ameliorates NF-kB-mediated skin diseases in mice The Journal of Clinical Investigation 2013; 123 (12): 5361-5370
A Systemic Complete Response of Metastatic Melanoma to Local Radiation and Immunotherapy
2012; 5 (6): 404-407
Melanoma is a relatively immunogenic tumor, in which infiltration of melanoma cells by T lymphocytes is associated with a better clinical prognosis. We hypothesized that radiation-induced cell death may provide additional stimulation of an anti-tumor immune response in the setting of anti-CTLA-4 treatment.In a pilot melanoma patient, we prospectively tested this hypothesis. We treated the patient with two cycles of ipilimumab, followed by stereotactic ablative radiotherapy to two of seven hepatic metastases, and two additional cycles of ipilimumab.Subsequent positron emission tomography-computed tomography scan indicated that all metastases, including unirradiated liver lesions and an unirradiated axillary lesion, had completely resolved, consistent with a complete response by RECIST.The use of radiotherapy in combination with targeted immunotherapy as a noninvasive in vivo tumor vaccine strategy appears to be a promising method of enhancing the induction of systemic immune responses and anti-tumor effect.
View details for DOI 10.1593/tlo.12280
View details for Web of Science ID 000313359800002
View details for PubMedID 23323154
View details for PubMedCentralID PMC3542835
The Scarlet Letter of Alkylation: A Mini Review of Selective Alkylating Agents
2012; 5 (4): 226-229
If there were a stigma scale for chemotherapy, alkylating agents would be ranked at the top of the list. The chemical term alkylation is associated with nonselective toxicity, an association that dates back to the use of nitrogen mustards during World War I as chemical warfare agents. That this stigma persists and extends to compounds that, through selectivity, attempt to "tame" the indiscriminate destructive potential of alkylation is the subject of this review. Selective alkylation, as it is referred to herein, constitutes an extremely nascent and dynamic field in oncology. The pharmacodynamic response to this selective strategy depends on a delicate kinetic balance between specificity and the rate and extent of binding. Three representative compounds are presented: RRx-001, 3-bromopyruvate, and TH-302. The main impetus for the development of these compounds has been the avoidance of the serious complications of traditional alkylating agents; therefore, it is the thesis of this review that they should not experience stigma by association.
View details for DOI 10.1593/tlo.12187
View details for Web of Science ID 000311488600001
View details for PubMedID 22937173
View details for PubMedCentralID PMC3431031
Mitigation of Radiation-Induced Dermatitis by Activation of Aldehyde Dehydrogenase 2 Using Topical Alda-1 in Mice
2012; 178 (1): 69-74
Radiation-induced dermatitis is a debilitating clinical problem in cancer patients undergoing cancer radiation therapy. It is also a possible outcome of exposure to high levels of radiation due to accident or hostile activity. We report that activation of aldehyde dehydrogenase 2 (ALDH2) enzymatic activity using the allosteric agonist, Alda-1, significantly reduced 4-hydroxynonenal adducts accumulation, delayed the onset of radiation dermatitis and substantially reduced symptoms in a clinically-relevant model of radiation-induced dermatitis. Importantly, Alda-1 did not radioprotect tumors in mice. Rather, it increased the sensitivity of the tumors to radiation therapy. This is the first report of reactive aldehydes playing a role in the intrinsic radiosensitivity of normal and tumor tissues. Our findings suggest that ALDH2 represents a novel target for the treatment of radiation dermatitis without reducing the benefit of radiotherapy.
View details for DOI 10.1667/RR2861.1
View details for Web of Science ID 000306940600008
View details for PubMedID 22404739
View details for PubMedCentralID PMC3417825
Darinaparsin: Solid Tumor Hypoxic Cytotoxin and Radiosensitizer
CLINICAL CANCER RESEARCH
2012; 18 (12): 3366-3376
Hypoxia is an important characteristic of the solid tumor microenvironment and constitutes a barrier for effective radiotherapy. Here, we studied the effects of darinaparsin (an arsenic cytotoxin) on survival and radiosensitivity of tumor cells in vitro under normoxia and hypoxia and in vivo using xenograft models, compared to effects on normal tissues.The cytotoxicity and radiosensitization of darinaparsin were first tested in vitro in a variety of solid tumor cell lines under both normoxia and hypoxia and compared with arsenic trioxide (ATO, an arsenical with reported cytotoxic and radiosensitizing activities on tumor cells). The effects were then tested in mouse models of xenograft tumors derived from tumor cell lines and clinical tumor specimens. The potential mechanisms of darinaparsin effects, including reactive oxygen species (ROS) generation, cellular damage, and changes in global gene expression, were also investigated.In comparison with ATO, darinaparsin had significantly higher in vitro cytotoxic and radiosensitizing activities against solid tumor cells under both normoxia and hypoxia. In vivo experiments confirmed these activities at doses that had no systemic toxicities. Importantly, darinaparsin did not radiosensitize normal bone marrow and actually radioprotected normal intestinal crypts. The darinaparsin-mediated antitumor effects under hypoxia were not dependent on ROS generation and oxidative damage, but were associated with inhibition of oncogene (RAS and MYC)-dependent gene expression.Darinaparsin has significant and preferential cytotoxic and radiosensitizing effects on solid tumors as compared with normal cells. Darinaparsin may therefore increase the therapeutic index of radiation therapy and has near term translational potential.
View details for DOI 10.1158/1078-0432.CCR-11-3179
View details for Web of Science ID 000307502100017
View details for PubMedID 22535156
Beyond Antiangiogenesis: Vascular Modulation as an Anticancer Therapy-A Review
2012; 5 (3): 133-140
This review attempts to move beyond the traditional borders of antiangiogenesis and toward the dynamic, evolving strategies of vascular modulation. This repositioning entails a two-fold paradigm shift: conceptually, to a view of antiangiogenesis as only one part of a larger story, and therapeutically, to approaches which attempt to modulate tumor blood flow instead of simply inhibiting it. Three vascular modulation strategies-provascular, antivascular, and redistributive-are presented with representative compounds. These vascular modulation strategies are described in specific measurable characteristics (blood vessel maturity and type, effect on blood flow, microenvironmental target, molecular target, angiogenic biomarker, and imaging biomarkers) that will help define the tumor types that are more susceptible to a particular vascular modulation strategy thereby guiding therapeutic agent selection and enabling a personalized medicine approach.
View details for DOI 10.1593/tlo.12118
View details for Web of Science ID 000311487900001
View details for PubMedID 22741032
View details for PubMedCentralID PMC3384267
- Abscopal Effect in a Patient with Melanoma NEW ENGLAND JOURNAL OF MEDICINE 2012; 366 (21): 2035-2035
Dinitroazetidines Are a Novel Class of Anticancer Agents and Hypoxia-Activated Radiation Sensitizers Developed from Highly Energetic Materials
2012; 72 (10): 2600-2608
In an effort to develop cancer therapies that maximize cytotoxicity, while minimizing unwanted side effects, we studied a series of novel compounds based on the highly energetic heterocyclic scaffold, dinitroazetidine. In this study, we report the preclinical validation of 1-bromoacetyl-3,3-dinitroazetidine (ABDNAZ), a representative lead compound currently in a phase I clinical trial in patients with cancer. In tumor cell culture, ABDNAZ generated reactive free radicals in a concentration- and time-dependent manner, modulating intracellular redox status and triggering apoptosis. When administered to mice as a single agent, ABDNAZ exhibited greater cytotoxicity than cisplatin or tirapazamine under hypoxic conditions. However, compared with cisplatin, ABDNAZ was better tolerated at submaximal doses, yielding significant tumor growth inhibition in the absence of systemic toxicity. Similarly, when combined with radiation, ABDNAZ accentuated antitumor efficacy along with the therapeutic index. Toxicity studies indicated that ABDNAZ was not myelosuppressive and no dose-limiting toxicity was apparent following daily administration for 14 days. Taken together, our findings offer preclinical proof-of-concept for ABDNAZ as a promising new anticancer agent with a favorable toxicity profile, either as a chemotherapeutic agent or a radiosensitizer.
View details for DOI 10.1158/0008-5472.CAN-11-2303
View details for Web of Science ID 000307346800015
View details for PubMedID 22589277
Is Nitric Oxide (NO) the Last Word in Radiosensitization? A Review
2012; 5 (2): 66-71
As a short-lived radical that diffuses across membranes, rather than interacting with membrane-bound receptors, nitric oxide (NO) represents a significant departure from synthetically derived radiosensitizers. An endogenous compound, NO may equal or surpass its molecular cousin, oxygen, as a hypoxic radiosensitizer, through pleiotropic phenotypic effects on tumor perfusion, cell signaling, mitochondrial respiration, the fixation of radiation-induced damage, and the radioprotection of normal tissue. However, unlike oxygen, in the context of radiosensitization, the clinical role and utility of NO are poorly understood, with often contradictory and controversial reported effects: whether NO functions as a radiosensitizer may ultimately be contextual to the tumor microenvironment. This may make NO manipulation an ideal candidate for a personalized radiosensitization approach tailored to specific patient and tumor types/microenvironmental characteristics. Effective delivery of NO both systemically and directly to the tumor may be critical to the success of this approach. Compounds that release NO or NO precursors have the potential to drive innovation and result in a new fertile branch of the radiosensitizer tree.
View details for DOI 10.1593/tlo.11307
View details for Web of Science ID 000311487700001
View details for PubMedID 22496921
View details for PubMedCentralID PMC3323926
Six degrees of separation: the oxygen effect in the development of radiosensitizers.
2011; 4 (4): 189-198
The popular theory six degrees of separation is used in this review as an analogy to relate all radiosensitization to oxygen. As the prime mover of all radiosensitizers, the pervasive influence of oxygen has consciously or unconsciously influenced the direction of research and development and provided the benchmark against which all other compounds and approaches are measured. It is the aim of this review to develop the six degrees of separation from oxygen analogy as a unifying framework for conceptually organizing the field and for giving context to its varied subspecializations and theories. Under such a framework, it would become possible for one area to consider questions and problems found in other areas of radiosensitization, using a common analogy, that would allow for further development and unification of this multifaceted discipline. In this review, approaches to the development of radiosensitizers and the current state of research in this field are discussed, including promising new agents in various stages of clinical development.
View details for PubMedID 21804913
Anti-tumor and radiosensitization activities of the iron chelator HDp44mT are mediated by effects on intracellular redox status
2010; 298 (2): 231-237
A novel iron chelator, HDp44mT, has been reported to have potent anti-proliferative effects on cancer cells; however, the underlying mechanism of action is not well understood. In this study, we characterized the cytotoxic effect of HDp44mT in a chemo- and radio-resistant cell line (PC-3) of prostatic cancer origin. The activity of HDp44mT at nM concentrations was dependent on the intracellular GSH and atmospheric O(2) concentration, rather than iron deprivation. HDp44mT also radiosensitized PC-3 cells in a GSH-dependent manner. Interestingly, this radiosensitizing effect was observed under aerobic and, to a larger extent, hypoxic conditions, suggesting its potential utility as a radiosensitizer for some radioresistant tumors.
View details for DOI 10.1016/j.canlet.2010.07.010
View details for Web of Science ID 000284300000011
View details for PubMedID 20678860
In Situ Vaccination With a TLR9 Agonist Induces Systemic Lymphoma Regression: A Phase I/II Study
JOURNAL OF CLINICAL ONCOLOGY
2010; 28 (28): 4324-4332
Combining tumor antigens with an immunostimulant can induce the immune system to specifically eliminate cancer cells. Generally, this combination is accomplished in an ex vivo, customized manner. In a preclinical lymphoma model, intratumoral injection of a Toll-like receptor 9 (TLR9) agonist induced systemic antitumor immunity and cured large, disseminated tumors.We treated 15 patients with low-grade B-cell lymphoma using low-dose radiotherapy to a single tumor site and-at that same site-injected the C-G enriched, synthetic oligodeoxynucleotide (also referred to as CpG) TLR9 agonist PF-3512676. Clinical responses were assessed at distant, untreated tumor sites. Immune responses were evaluated by measuring T-cell activation after in vitro restimulation with autologous tumor cells.This in situ vaccination maneuver was well-tolerated with only grade 1 to 2 local or systemic reactions and no treatment-limiting adverse events. One patient had a complete clinical response, three others had partial responses, and two patients had stable but continually regressing disease for periods significantly longer than that achieved with prior therapies. Vaccination induced tumor-reactive memory CD8 T cells. Some patients' tumors were able to induce a suppressive, regulatory phenotype in autologous T cells in vitro; these patients tended to have a shorter time to disease progression. One clinically responding patient received a second course of vaccination after relapse resulting in a second, more rapid clinical response.In situ tumor vaccination with a TLR9 agonist induces systemic antilymphoma clinical responses. This maneuver is clinically feasible and does not require the production of a customized vaccine product.
View details for DOI 10.1200/JCO.2010.28.9793
View details for Web of Science ID 000282272700032
View details for PubMedID 20697067
View details for PubMedCentralID PMC2954133
Anti-alpha v Integrin Monoclonal Antibody Intetumumab Enhances the Efficacy of Radiation Therapy and Reduces Metastasis of Human Cancer Xenografts in Nude Rats
2010; 70 (19): 7591-7599
We previously reported that intetumumab (CNTO 95), a fully human anti-αv integrin monoclonal antibody, is a radiosensitizer in mice with xenograft tumors. Because intetumumab does not cross-react with mouse integrins, but has cross-reactivity with rat integrins, we next studied the potential combined use of radiation therapy and intetumumab in human cancer xenograft models in nude rats to assess effects on both tumor cells and the tumor microenvironment. Nude rats bearing human head and neck cancer and non-small cell lung cancer (NSCLC) xenografts were treated with intetumumab and fractionated local tumor radiotherapy. Effects on tumor growth and metastasis, blood perfusion, oxygenation, and gastrointestinal toxicity were studied. Intetumumab alone had a moderate effect on tumor growth. When combined with fractionated radiation therapy, intetumumab significantly inhibited tumor growth and produced a tumor response rate that was significantly better than with radiation therapy alone. Treatment with intetumumab also significantly reduced lung metastasis in the A549 NSCLC xenograft model. The oxygenation and blood perfusion in xenograft tumors measured by microbubble-enhanced ultrasound imaging were substantially increased after treatment with intetumumab. The combined use of intetumumab and radiation therapy reduced the microvessel density and increased apoptosis in tumor cells and the tumor microenvironment. Toxicity studies showed that treatment with intetumumab did not cause the histopathologic changes in the lungs and did not sensitize the sensitive gastrointestinal epithelium to the effect of radiation therapy. Intetumumab can potentiate the efficacy of fractionated radiation therapy in human cancer xenograft tumors in nude rats without increased toxicity.
View details for DOI 10.1158/0008-5472.CAN-10-1639
View details for Web of Science ID 000282647700023
View details for PubMedID 20841470
SODIUM SELENITE RADIOSENSITIZES HORMONE-REFRACTORY PROSTATE CANCER XENOGRAFT TUMORS BUT NOT INTESTINAL CRYPT CELLS IN VIVO
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
2010; 78 (1): 230-236
We have previously shown that sodium selenite (SSE) increases radiation-induced cell killing of human prostate carcinoma cells in vitro. In this study we further evaluated the in vivo radiosensitizing effect of SSE in prostate cancer xenograft tumors and normal radiosensitive intestinal crypt cells.Immunodeficient (SCID) mice with hormone-independent LAPC-4 (HI-LAPC-4) and PC-3 xenograft tumors (approximately 200 mm(3)) were divided into four groups: control (untreated), radiation therapy (XRT, local irradiation), SSE (2 mg/kg, intraperitoneally, 3 times/week), and XRT plus SSE. The XRT was given at the beginning of the regimen as a single dose of 5 Gy for HI-LAPC-4 tumors and a single dose of 7 Gy followed by a fractional dose of 3 Gy/d for 5 days for PC-3 tumors. The tumor volume was measured 3 times per week. The radiosensitizing effect of SSE on normal intestinal epithelial cells was assessed by use of a crypt cell microcolony assay.In the efficacy study, SSE alone significantly inhibited the tumor growth in HI-LAPC-4 tumors but not PC-3 tumors. Sodium selenite significantly enhanced the XRT-induced tumor growth inhibition in both HI-LAPC-4 and PC-3 tumors. In the toxicity study, SSE did not affect the intestinal crypt cell survival either alone or in combination with XRT.Sodium selenite significantly enhances the effect of radiation on well-established hormone-independent prostate tumors and does not sensitize the intestinal epithelial cells to radiation. These results suggest that SSE may increase the therapeutic index of XRT for the treatment of prostate cancer.
View details for DOI 10.1016/j.ijrobp.2010.03.006
View details for Web of Science ID 000281304600033
View details for PubMedID 20615620
Metalloporphyrin Synergizes with Ascorbic Acid to Inhibit Cancer Cell Growth Through Fenton Chemistry
CANCER BIOTHERAPY AND RADIOPHARMACEUTICALS
2010; 25 (4): 439-448
Ascorbic acid (AA) has been reported to inhibit tumor cell growth through the generation of extracellular hydrogen peroxide (H(2)O(2)). However, the clinical utility of AA has been limited by relatively low potency and in vivo efficacy. This study reports that the metalloporphyrin, Mn(III) tetrakis(N-methylpyridinium-2-yl)porphyrin(5+) (MnTMPyP), has a potent synergistic cytotoxic effect when combined with AA in a variety of cancer cell lines. In the presence of MnTMPyP, the concentration of AA required to inhibit cancer cell growth was markedly reduced. In vitro (cell-free) experiments demonstrated that AA alone enhanced the Fenton reaction that produces cytotoxic hydroxyl radical (HO(*)); however, this reaction was limited by the low rate by which AA generates H(2)O(2) (Fenton reaction substrate) from O(2). MnTMPyP catalyzed H(2)O(2) generation through the AA-facilitated Mn(II <--> III)TMPyP redox cycle and thereby markedly potentiated the Fenton reaction. Accordingly, MnTMPyP and AA resulted in increased cellular levels of H(2)O(2) and HO(*) in cancer cells, which mediate the synergistic cytotoxicity of this combined treatment. This effect was inhibited by cellular enzymes that metabolize H(2)O(2), such as catalase and glutathione peroxidase, suggesting that selective killing of cancer cells deficient in such enzymes can be achieved in vivo.
View details for DOI 10.1089/cbr.2009.0756
View details for Web of Science ID 000281255100008
View details for PubMedID 20735206
I-131-Tositumomab (BexxarA (R)) vs. Y-90-Ibritumomab (ZevalinA (R)) Therapy of Low-Grade Refractory/Relapsed Non-Hodgkin Lymphoma
MOLECULAR IMAGING AND BIOLOGY
2010; 12 (2): 198-203
The American Cancer Society estimated 66,120 new cases of non-Hodgkin lymphoma (NHL) in the USA in 2008. Radioimmunotherapy has been shown in clinical trials to be an effective treatment for refractory/relapsed NHL. The available agents are Bexxar, a (131)I radiolabeled murine monoclonal antibody, and Zevalin, a (90)Y radiolabeled murine antibody. Both target CD20 receptors present on the surface of lymphocytes. We present our clinical experience with Bexxar and Zevalin in the management of low-grade refractory or relapsed NHL.This is a retrospective study (Jan 2000-Jul 2006) of 67 patients with NHL, who were treated with Bexxar (31 patients, group A) or Zevalin (36 patients, group B) for refractory/relapsed disease. Group A included 16 men and 15 women, 35-81 years old (average, 59.3 +/- 13.4). Group B included 27 men and nine women, 36-85 years old (average, 55.4 +/- 13.8). Therapeutic doses ranged 40-138 mCi (average, 78.1 +/- 28.2) for Bexxar and 17-34 mCi (average, 28.8 +/- 4.37) for Zevalin.Objective responses were induced in 22 of the 31 patients (70.9%) in group A and 28 of the 36 patients (77.8%) in group B. Complete response was noted in 11 patients (35.5%), partial response in seven patients (22.6%), and mixed response in four patients (12.9%) in group A. There were five patients (16.1%) with stable disease and four patients (12.9%) with disease progression in the same group. Complete response was noted in 15 patients (41.7%), partial response in nine patients (25%), and mixed response in four patients (11.1%) in group B. There were four patients (11.1%) with stable disease and another four patients (11.1%) with disease progression in the same group. The average decreases at posttherapy nadir were 36.9% +/- 0.33 (group A) and 52.6% +/- 0.32 (group B) for platelets, 27.8% +/- 0.27 (group A) and 34.2% +/- 0.38 (group B) for leukocytes, and 4.9% +/- 0.15 (group A) and 7.6% +/- 0.11 (group B) for hemoglobin. Grades 3 and 4 hematological toxicity occurred in 14 patients (45.2%) treated with Bexxar and 22 patients (61.1%) treated with Zevalin, but was reversible.Our study suggests that clinical practice of Bexxar and Zevalin radioimmunotherapy is an effective and safe adjunctive treatment for patients with NHL refractory/relapsed to conventional treatment. However, due to the small number of subjects, it was not possible to determine whether differences in the outcomes or toxicities from the two agents were statistically significant.
View details for DOI 10.1007/s11307-009-0245-9
View details for Web of Science ID 000275974900010
View details for PubMedID 19543946
Impact of Rituximab Treatment on Y-90-Ibritumomab Dosimetry for Patients with Non-Hodgkin Lymphoma
JOURNAL OF NUCLEAR MEDICINE
2010; 51 (1): 150-157
To determine whether the therapeutic effect of (90)Y-ibritumomab might be enhanced by a full course of rituximab followed by single dose of (90)Y-ibritumomab, the trial included pre- and post-rituximab treatment imaging with (111)In-ibritumomab and blood pharmacokinetics. Comparison of the pre- and post-rituximab imaging and blood data allowed for the assessment of impact of rituximab on (90)Y-ibritumomab dosimetry.Seventeen patients with relapsed B cell non-Hodgkin lymphoma first received 250 mg/m(2) of rituximab plus 185 MBq of (111)In-ibritumomab for initial dosimetry evaluation. In weeks 2-4, patients received 3 weekly 375 mg/m(2) doses of rituximab. In week 6, patients received a 250 mg/m(2) dose of rituximab plus 185 MBq of (111)In-ibritumomab for a second dosimetry evaluation. Five sequential, whole-body gamma-camera images were acquired after the (111)In-ibritumomab injection. Calculated radiation doses were based on patient-specific organ masses. For each patient, paired comparison of radiation doses before and after rituximab treatment was performed. Paired comparison of residence times for spleen and tumor was also performed.Before rituximab treatment, the median radiation dose (mGy/MBq) was 0.48 (range, 0.24-0.86) for total body, 3.7 (range, 2.1-11.6) for liver, 6.1 (range, 1.8-17.8) for spleen, 3.3 (range, 2.0-4.7) for kidneys, 2.4 (range, 1.3-3.7) for heart wall, 1.1 (range, 0.4-2.3) for lungs, 0.79 (range, 0.32-1.22) for marrow from blood, and 18.1 (range, 4.7-98.9) for tumor. Paired comparisons were performed in 16 patients only because human antimurine antibody developed in 1 patient. The median change was 0.007 mGy/MBq for body, -0.14 mGy/MBq for liver, -0.31 mGy/MBq for kidneys, 0.38 mGy/MBq for heart wall, -0.17 mGy/MBq for lungs, and 0.046 mGy/MBq for marrow from blood. The median change in residence time was -0.92 h for spleen and -0.24 h for tumor. The changes were statistically insignificant for total body, liver, kidneys, lungs, and marrow from blood. The median residence times, or mGy/MBq if there were no volume changes, decreased 24% for spleen (P = 0.0005) and 28% for tumor (P = 0.005). The median radiation dose to heart wall increased 16%, which was statistically significant (P = 0.002).Changes in (90)Y-ibritumomab dosimetry after 4 wk of rituximab treatment were not significant for most organs, except for the heart wall. The reduction of spleen and tumor residence times is more likely to be due to the therapeutic effects of rituximab.
View details for DOI 10.2967/jnumed.109.066597
View details for Web of Science ID 000273263800026
View details for PubMedID 20008989
Impact of Radiation on Immunotherapy Targets
24th Annual Meeting of the International-Society-for-Biology-Therapy-of-Cancer
LIPPINCOTT WILLIAMS & WILKINS. 2009: 971–72
View details for Web of Science ID 000271110100101
Lanreotide promotes apoptosis and is not radioprotective in GH3 cells
2009; 16 (3): 1045-1055
Somatostatin analogs are a mainstay of medical therapy in patients with GH producing human pituitary tumors, and it has been suggested that somatostatin analogs may be radioprotective. We utilized GH secreting rat GH3 cells to investigate whether a somatostatin analog may limit the effects of radiation on proliferation and apoptosis in vitro and on tumor growth in vivo. Treatment with lanreotide alone at doses of either 100 or 1000 nM for 48 h reduced clonogenic survival by 5-10%. Radiation alone produced a dose-dependent survival curve with a SF2 of 48-55%, and lanreotide had no effect on this curve. The addition of lanreotide resulted in a 23% increase in the proportion of apoptotic sub-G1 cells following irradiation (P<0.01). In a mouse GH3 tumor xenograft model, lanreotide 10 mg/kg moderately inhibited the growth of GH3 tumors, with a 4x tumor growth delay (TGD) time that ranged from 4.5 to 8.3 days. Fractionated local tumor radiation alone significantly inhibited tumor growth and produced a TGD of 35.1+/-5.7 days for 250 cGy fractions. The combination of lanreotide, either antecedent to or concurrent, with radiation of 250, 200 or 150 cGy/fraction for 5 days inhibited tumor growth and produced the TGD times that were similar to radiation alone (P>0.05). Pretreatment with lanreotide had the most significant radiosensitizing effect. These studies demonstrate that the somatostatin analog lanreotide is not radioprotective in GH3 cells, and further studies are necessary to determine the impact of lanreotide on apoptosis.
View details for DOI 10.1677/ERC-09-0003
View details for Web of Science ID 000272670300027
View details for PubMedID 19528243
Identification of Novel Radiation Induced Immune Signaling Changes in Antigen Presenting Cells
51st Annual Meeting of the American-Society-for-Radiation-Oncology (ASTRO)
ELSEVIER SCIENCE INC. 2009: S545–S545
View details for Web of Science ID 000270573602120
Selenite treatment inhibits LAPC-4 tumor growth and prostate-specific antigen secretion in a xenograft model of human prostate cancer
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
2008; 72 (3): 935-940
Selenium compounds have known chemopreventive effects on prostate cancer. However selenite, an inorganic form of selenium, has not been extensively studied as a treatment option for prostate cancer. Our previous studies have demonstrated the inhibition of androgen receptor expression and androgen stimulated prostate-specific antigen (PSA) expression by selenite in human prostate cancer cell lines. In this study, we investigated the in vivo effects of selenite as a therapy to treat mice with established LAPC-4 tumors.Male mice harboring androgen-dependent LAPC-4 xenograft tumors were treated with selenite (2 mg/kg intraperitoneally three times per week) or vehicle for 42 days. In addition, androgen-independent LAPC-4 xenograft tumors were generated in female mice over 4 to 6 months. Once established, androgen-independent LAPC-4 tumor fragments were passaged into female mice and were treated with selenite or vehicle for 42 days. Changes in tumor volume and serum PSA levels were assessed.Selenite significantly decreased androgen-dependent LAPC-4 tumor growth in male mice over 42 days (p < 0.001). Relative tumor volume was decreased by 41% in selenite-treated animals compared with vehicle-treated animals. The inhibition of LAPC-4 tumor growth corresponded to a marked decrease in serum PSA levels (p < 0.01). In the androgen-independent LAPC-4 tumors in female mice, selenite treatment decreased tumor volume by 58% after 42 days of treatment (p < 0.001).These results suggest that selenite may have potential as a novel therapeutic agent to treat both androgen-dependent and androgen-independent prostate cancer.
View details for DOI 10.1016/j.ijrobp.2008.07.005
View details for Web of Science ID 000259894300043
View details for PubMedID 18760546
Risks to normal tissues from radionuclide therapy
SEMINARS IN NUCLEAR MEDICINE
2008; 38 (5): 347-357
The development of radionuclide therapies during the past few decades provides a growing body of data on radiobiologic effects, including normal tissue toxicities and antitumor efficacy. Information on normal tissue toxicity from radionuclides is more limited than that from external beam radiation and appears to be more variable. Much of the increased variability is attributed to heterogeneous distribution, which complicates the potential for whole-organ toxicity, and the differences in dosimetry methodology. Although new tools are becoming available, quantitation of heterogeneous dose for radionuclides is usually less precise than dosimetry that is used in external beam radiation practice. The correlation between reported dose estimates and toxicity has improved during the past 2 decades, partly as the result of increased accuracy and standardization of dosimetry techniques and to adjustment for biologic effects. This review provides an updated compendium of dose-response relationships and consideration of dosimetry as well as radiobiologic factors that influence the reported results. Data presented are mainly derived from studies involving deliver of radiation to adults with malignancies, with most experience from radionuclides that predominantly emit beta radiation.
View details for DOI 10.1053/j.semnuclmed.2008.05.001
View details for Web of Science ID 000258391300006
View details for PubMedID 18662556
Anti-integrin monoclonal antibody CNTO 95 enhances the therapeutic efficacy of fractionated radiation therapy in vivo
MOLECULAR CANCER THERAPEUTICS
2008; 7 (6): 1569-1578
Selective targeting of up-regulated integrins on tumor cells is a novel antiangiogenesis strategy for treating solid tumors. CNTO 95 is a fully human anti-alpha(v) integrin monoclonal antibody and has shown antitumor activity when used as a single agent in preclinical studies. We previously showed that radiation combined with an integrin alpha(v)beta(3) antagonist cRGD peptide increased the therapeutic efficacy of radiation in preclinical tumor models. We hypothesized that the combination of radiation and CNTO 95 would synergistically enhance the efficacy of radiation therapy. The in vitro studies showed that CNTO 95 radiosensitized and induced apoptosis in M21 cells in vitronectin-coated dishes. In mice bearing established human cancer xenograft tumors, CNTO 95 alone had only a moderate effect on tumor growth. The combined therapy of CNTO 95 and fractionated radiation significantly inhibited tumor growth and produced the longer tumor growth delay time in multiple tumor models. Maintenance dosing of CNTO 95 following irradiation contributed to efficacy and was important for continued inhibition of tumor regrowth. Immunohistochemistry studies showed that the combined use of CNTO 95 and radiation reduced the alpha(v) integrin and vascular endothelial growth factor receptor expression and the microvessel density and increased apoptosis in tumor cells and the tumor microenvironment. CNTO 95 alone and in combination with radiation did not produce any obvious signs of systemic toxicity. These results show that CNTO 95 can potentiate the efficacy of fractionated radiation therapy in a variety of human cancer xenograft tumor types in nude mice. These findings are very promising and may have high translational relevance for the treatment of patients with solid tumors.
View details for DOI 10.1158/1535-7163.MCT-08-0288
View details for Web of Science ID 000256955900024
View details for PubMedID 18566227
CNTO 95, a monoclonal antibody against alpha v integrins, enhances the therapeutic efficacy of fractionated radiation therapy in vivo.
AMER ASSOC CANCER RESEARCH. 2007: 3537S–3537S
View details for Web of Science ID 000251969000621
MIRD continuing education: Bystander and low-dose-rate effects: Are these relevant to Radionuclide therapy?
JOURNAL OF NUCLEAR MEDICINE
2007; 48 (10): 1683-1691
Bystander and low-dose-rate effects influence the dose-response relationship in a manner not predicted by current dosimetric methodologies. Radiation-induced bystander effects refer to biologic responses in cells that are not traversed by an ionizing radiation track and, thus, not subject to direct energy deposition; that is, the responses occur in nonirradiated cells. Low-dose-rate hypersensitivity effects have been documented as a reduction in the survival of cells irradiated at dose rates of 0.1-1.0 Gy/h, with total doses ranging from 1.5 to 5 Gy. For humans undergoing external radiotherapy, evidence of bystander events has been observed in the form of abscopal effects, wherein irradiation of one portion of the anatomy affects a portion outside the radiation field, whereas low-dose-rate hypersensitivity has not been described. In this report, the historical literature is briefly reviewed, key experiments are summarized, and current understanding of the factors thought to be involved in the bystander and low-dose-rate effects is conveyed. The mechanisms associated with these events are still being investigated, and questions remain on their impact in radionuclide therapy. Although current findings do not yet sufficiently justify changing traditional dose estimates used to predict the outcomes of radionuclide therapy, it is important to appreciate the potential importance of these effects and to begin revising methods to reflect the emerging empiric and mechanistic knowledge.
View details for DOI 10.2967/jnumed.105.028183
View details for Web of Science ID 000252894800039
View details for PubMedID 17873139
Expression and function of erythropoietin receptors in tumors - Implications for the use of erythropoiesis-stimulating agents in cancer patients
2007; 110 (3): 477-488
Safety concerns surrounding the use of recombinant human erythropoietin (Epo) to treat anemia in cancer patients were raised after 2 recent clinical studies reported a worse survival outcome in patients who received epoetin alpha or epoetin beta compared with patients who received placebo. Although those findings contrasted with previous clinical studies, which demonstrated no difference in survival for cancer patients who received erythropoiesis-stimulating agents (ESAs), some investigators have suggested a potential role for ESAs in promoting tumor growth through 1) stimulation of Epo receptors (EpoR) expressed in tumors, 2) stimulation and formation of tumor vessels, and/or 3) enhanced tumor oxygenation. The first and second hypotheses appeared to be supported by some EpoR expression and ESA in vitro studies. However, these conclusions have been challenged because of poor specificity of EpoR-detection methodologies, conflicting data from different groups, and the lack of correlation between in vitro data and in vivo findings in animal tumor models. For this report, the authors reviewed the biology of EpoR in erythropoiesis and compared and contrasted the reported findings on the role of ESAs and EpoR in tumors.
View details for DOI 10.1002/cncr.22832
View details for Web of Science ID 000248206700002
View details for PubMedID 17582631
Targeting integrins and PI3K/Akt-mediated signal transduction pathways enhances radiation-induced anti-angiogenesis
2007; 168 (1): 125-133
The integrins and PI3K/Akt are important mediators of the signal transduction pathways involved in tumor angiogenesis and cell survival after exposure to ionizing radiation. Selective targeting of either integrins or PI3K/Akt can radiosensitize tumors. In this study, we tested the hypothesis that the combined inhibition of integrin alphanubeta3 by cRGD and PI3K/Akt by LY294002 would significantly enhance radiation-induced inhibition of angiogenesis by vascular endothelial cells. Treatment with cRGD inhibited the adhesion and tube formation of human umbilical vein endothelial cells (HUVECs). The inhibitory effect was further increased when cRGD and LY294002 were applied simultaneously. Both radiation and cRGD induced Akt phosphorylation, up-regulated COX2 expression, and increased PGE2 production in HUVECs. Treatment with LY294002 effectively inhibited radiation- and cRGD-induced Akt phosphorylation and up-regulation of COX2 and increased apoptosis of HUVECs. The combined use of cRGD and LY294002 enhanced radiation-induced cell killing. The clonogenic survival of HUVECs was decreased from 34% with 2 Gy radiation to 4% with these agents combined. These results demonstrate that combined use of ionizing radiation, cRGD and LY294002 inhibited multiple signaling transduction pathways involved in tumor angiogenesis and enhanced radiation-induced effects on vascular endothelial cells.
View details for Web of Science ID 000247607900009
View details for PubMedID 17722999
Clinical efficacy of zanolimumab (HuMax-CD4): two phase 2 studies in refractory cutaneous T-cell lymphoma
2007; 109 (11): 4655-4662
The efficacy and safety of zanolimumab in patients with refractory cutaneous T-cell lymphoma (CTCL) have been assessed in two phase 2, multicenter, prospective, open-label, uncontrolled clinical studies. Patients with treatment refractory CD4(+) CTCL (mycosis fungoides [MF], n = 38; Sézary syndrome [SS], n = 9) received 17 weekly infusions of zanolimumab (early-stage patients, 280 and 560 mg; advanced-stage patients, 280 and 980 mg). The primary end point was objective response (OR) as assessed by composite assessment of index lesion disease activity score. Secondary end points included physician's global assessment (PGA), time to response, response duration, and time to progression. ORs were recorded for patients in both CTCL types (MF, 13 ORs; SS, 2 ORs). In the high-dose groups (560 and 980 mg dose groups), a response rate of 56% was obtained with a median response of 81 weeks. Adverse events reported most frequently included low-grade infections and eczematous dermatitis. Zanolimumab showed marked clinical efficacy in the treatment of patients with refractory MF, with early onset of response, high response rate, and durable responses. The treatment was well tolerated with no dose-related toxicity other than the targeted depletion of peripheral T cells. A pivotal study has been initiated based on these findings.
View details for DOI 10.1182/blood-2006-12-062877
View details for Web of Science ID 000246946100017
View details for PubMedID 17311990
Inhibition of androgen receptor signaling by selenite and methylseleninic acid in prostate cancer cells: two distinct mechanisms of action
MOLECULAR CANCER THERAPEUTICS
2006; 5 (8): 2078-2085
The development of prostate cancer and its progression to a hormone-refractory state is highly dependent on androgen receptor (AR) expression. Recent studies have shown that the selenium-based compound methylseleninic acid (MSeA) can disrupt AR signaling in prostate cancer cells. We have found that selenite can inhibit AR expression and activity in LAPC-4 and LNCaP prostate cancer cells as well but through a different mechanism. On entering the cell, selenite consumes reduced glutathione (GSH) and generates superoxide radicals. Pretreatment with N-acetylcysteine, a GSH precursor, blocked the down-regulation of AR mRNA and protein expression by selenite and restored AR ligand binding and prostate-specific antigen expression to control levels. MSeA reacts with reduced GSH within the cell; however, N-acetylcysteine did not effect MSeA-induced down-regulation of AR and prostate-specific antigen. The superoxide dismutase mimetic MnTMPyP was also found to prevent the decrease in AR expression caused by selenite but not by MSeA. A Sp1-binding site in the AR promoter is a key regulatory component for its expression. Selenite decreased Sp1 expression and activity, whereas MSeA did not. The inhibition of Sp1 by selenite was reversed in the presence of N-acetylcysteine. In conclusion, we have found that selenite and MSeA disrupt AR signaling by distinct mechanisms. The inhibition of AR expression and activity by selenite occurs via a redox mechanism involving GSH, superoxide, and Sp1.
View details for DOI 10.1158/1535-7163.MCT-06-0056
View details for Web of Science ID 000240029400021
View details for PubMedID 16928829
Optimization of combination therapy of arsenic trioxide and fractionated radiotherapy for malignant glioma
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
2006; 65 (2): 493-498
The primary objective was to optimize the combined treatment regimen using arsenic trioxide (ATO) and fractionated radiotherapy for the treatment of malignant glioma.Nude mice with human glioma xenograft tumors were treated with fractionated local tumor radiation of 250 cGy/fraction/day and 5 mg/kg ATO for 5-10 days.Time course experiments demonstrated that maximal tumor growth delay occurred when ATO was administered between 0 and 4 h after radiation. The combination treatment of ATO and radiation synergistically inhibited tumor growth and produced a tumor growth delay time of 13.2 days, compared with 1.4 days and 6.5 days for ATO and radiation alone (p < 0.01), respectively. The use of concurrent therapy of radiation and ATO initially, followed by ATO as maintenance therapy, was superior to the use of preloading with ATO before combined therapy and produced a tumor growth delay time of 22.7 days as compared with 11.7 days for the ATO preloading regimen (p < 0.01). The maintenance dose of ATO after concurrent therapy was effective and important for continued inhibition of tumor growth.The combined use of fractionated radiation and ATO is effective for the treatment of glioma xenograft tumors. ATO was most effective when administered 0-4 h after radiation without pretreatment with ATO. These results have important implications for the optimization of treatment regimen using ATO and fractionated radiotherapy for the treatment of brain tumors.
View details for DOI 10.1016/j.ijrobp.2005.12.015
View details for Web of Science ID 000237543800026
View details for PubMedID 16563655
Phase I study of I-131-chimeric(ch) TNT-1/B monoclonal antibody for the treatment of advanced colon cancer
CANCER BIOTHERAPY AND RADIOPHARMACEUTICALS
2006; 21 (3): 243-256
The primary aim of this study was to evaluate the biodistribution and toxicity of 131I-chimeric(ch) TNT-1/B monoclonal antibody (MAB), which binds to intracellular antigens of necrotic regions within tumors, in patients with advanced colon or colorectal cancer. The rationale for targeting areas of tumor necrosis is the observation that necrotic lesions are more abundant in cancer lesions than in surrounding tissues.Cohorts of patients with advanced colon or colorectal cancer were administered a one-time 30-60-minute intravenous (i.v.) infusion of 131I-chTNT-1/B at doses ranging from 12.95 to 66.23 MBq/kg (0.35-1.79 mCi/kg).The dose-limiting toxicity, experienced at 66.23 MBq/kg (1.79 mCi/kg) 131I-chTNT-1/B MAB, was myelosuppression. Two (2) patients at the 66.23-MBq/kg (1.79 mCi/kg) dose level had both grade 3 thrombocytopenia and grade 3 neutropenia that persisted for at least 2 weeks but were reversible. The maximum tolerated dose was 58.09 MBq/kg (1.57 mCi/kg) 131I-chTNT-1/B MAB. Of the 21 patients, one developed a moderate human antichimeric antibody (HACA) response and 6 developed low HACA responses.The infusion of 131I-chTNT-1/B MAB was well tolerated, without significant nonhematological toxicity. No patient obtained a complete or partial response, based on tumor cross-product response criteria. Tumor localization was seen in patients with dose levels at, and exceeding, 50.23 MBq/kg (1.36 mCi/kg) 131I-chTNT-1/B MAB.
View details for Web of Science ID 000239162600010
View details for PubMedID 16918301
Radiation sensitization with redox modulators: A promising approach
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
2006; 64 (2): 343-354
Radiation therapy plays a critical role in the local and regional control of malignant tumors. Its efficacy, however, is limited by a number of factors, including toxicity, tumor hypoxia, and tumor genetics. Recent attempts to enhance the efficacy of radiation therapy have focused on biologic agents that modulate reduction/oxidation reactions within tumor cells.We review five promising redox modulators that are in development. Tirapazamine and AQ4N are known as "hypoxic cell sensitizers" and are toxic in areas of low oxygen tension. RSR13 facilitates delivery of oxygen to tumor cells, thereby rendering them more sensitive to radiation. Motexafin gadolinium, with a porphyrin-like structure, selectively accumulates in tumor cells and thereby enhances radiation-induced DNA damage. HIF-1 inhibitors target a transcription factor that regulates hypoxia-related events and cell survival.Our review of each agent included a thorough search of published preclinical and clinical data, including that presented in abstracts and posters at international meetings. Our objectives were not to identify a superior mechanism or drug, but rather to summarize the available safety and efficacy data.Clearly, there is an unmet need for safer agents that augment the efficacy of radiation therapy. This review highlights five promising redox modulators that are in development. None has yet been approved by the Food and Drug Administration. These drugs were selected for discussion because they exemplify the current investigative landscape of radiosensitizers and are indicative of future directions in this area. These radiation sensitizers have the potential to succeed where others have failed, by locally increasing the radiosensitivity of tumor cells without enhancing that of surrounding normal tissues.
View details for DOI 10.1016/j.ijrobp.2005.10.013
View details for Web of Science ID 000234883300002
View details for PubMedID 16414370
Tumor-selective killing by selenite in patient-matched pairs of normal and malignant prostate cells
2006; 66 (2): 218-225
Selenium compounds have been shown to induce apoptosis in a variety of human prostate cancer cell lines. However, the effects of selenium have yet to be examined in normal and malignant cells derived from the same individual. Selenite metabolism consumes glutathione (GSH) and produces superoxide. The generation of reactive oxygen species is an important mechanism in selenite-induced apoptosis.Three patient-matched pairs of primary prostatic epithelial cell cultures from normal and cancer were evaluated for their response to selenite. Apoptosis was measured and the differential response of normal and cancer cells was correlated with the expression of bcl-2, bax, GSH, and manganese superoxide dismutase (MnSOD).The cancer-derived cells were significantly more sensitive to selenite-induced apoptosis than the corresponding normal cells. Tumor-selective killing was not observed in cells treated with selenomethionine. The ratio of bcl-2:bax was decreased in the cancer-derived cells treated with selenite. Total GSH concentrations were similar in paired normal and cancer cells. Therefore, differences in GSH content do not appear to play a role in tumor-selective killing by selenite. Superoxide is a by-product of selenite metabolism and normal cells showed increased MnSOD expression and SOD activity compared to the cancer-derived cells. Prostate cancer cells treated with the MnSOD mimetic, MnTMPyP, were protected against the cytotoxic effects of selenite.Higher MnSOD expression in normal cells may play an important role in eliminating superoxide radicals produced as a result of selenite metabolism and contribute to the tumor-selective killing by selenite in prostate cancer.
View details for DOI 10.1002/pros.20337
View details for Web of Science ID 000234838300011
View details for PubMedID 16173037
Clinical manifestations of noncoronary atherosclerotic vascular disease after moderate dose irradiation
2006; 106 (3): 718-725
Accelerated atherosclerosis and carotid stenosis are well-established risks occurring after high radiation doses that are used to treat cancers of the head and neck. Noncoronary vascular disease has been observed and may relate to more moderate dose irradiation.A search of patients treated for Hodgkin disease, non-Hodgkin lymphoma, or seminoma was performed to identify cases with noncoronary vascular complications after irradiation. These three groups were chosen because of the use of intermediate dose radiation and prevalence of long-term survivors. Individual patient records were reviewed to document the type and presentation of the stenosis and the clinical factors that may have contributed to this risk.Twenty-one patients were identified who developed disease in noncoronary arteries after treatment. The median time from irradiation to diagnosis of vascular stenosis was 15 years. Antecedent risk factors for vascular disease were prevalent. Five patients had disease identified by auscultation of bruits before an adverse clinical event occurred. Five patients died from complications related to their vascular disease, which included three deaths after stroke and two after small bowel infarction.Twelve cases arose at an atypically young age for atherosclerotic vascular disease and featured unusual clinical presentations. Nine cases identified occurred at an advanced aged and at a shorter median interval, making a causal relation to irradiation uncertain. Incorporating careful auscultation for bruits in followup evaluation of irradiated patients may identify individuals who are at risk for adverse vascular events. The potential for early vasculopathy in individuals exposed to intermediate dose irradiation suggests a need to manage dyslipidemia and reduce vascular risk factors throughout the posttreatment period.
View details for DOI 10.1002/cncr.21636
View details for Web of Science ID 000234822700028
View details for PubMedID 16353211
Clinical development of radioimmunotherapy for B-cell non-Hodgkin's lymphoma
Systemics Targeted Radionuclide Therapy Symposium (STaRT)
ELSEVIER SCIENCE INC. 2006: S15–S22
Over the past several decades, several biomolecules have been investigated for their ability to deliver radiation to cancer cells, but antibodies have been the carriers of choice in systemic targeted radionuclide therapy (STaRT). Two radioimmunotherapy agents that target the CD20 antigen, (131)I-tositumomab and (90)Y-ibritumomab tiuxetan, have been approved by the U.S. Food and Drug Administration for the treatment of patients with relapsed or refractory B-cell non-Hodgkin's lymphoma (NHL), and clinical trials have shown that they are effective as monotherapies in the salvage setting, producing response rates that are often higher and durations of response that are often longer than those with chemotherapy. Escalated doses of these agents can be supported with stem cell transplantation and can produce high rates of complete response and greater survival in patients with relapsed NHL. The quality and duration of responses are greater with radioimmunotherapy when it is used earlier in the course of treatment.
View details for DOI 10.1016/j.ijrobp.2006.04.059
View details for Web of Science ID 000240805700006
View details for PubMedID 16979433
A preliminary report of a phase I study of Zevalin (R) using a modified treatment regimen for relapsed or refractory CD20+B-cell follicular or transformed non-Hodgkin's lymphoma (NHL)
47th Annual Meeting of the American-Society-of-Hematology
AMER SOC HEMATOLOGY. 2005: 280B–280B
View details for Web of Science ID 000233426101500
Re-treatment with I-131 tositumomab in patients with non-Hodgkin's lymphoma who had previously responded to I-131 tositumomab
45th Annual Meeting and Exhibition of the American-Society-of-Hematology
AMER SOC CLINICAL ONCOLOGY. 2005: 7985–93
To study efficacy and safety of re-treatment with I-131 tositumomab in patients with low-grade, follicular, or transformed low-grade B-cell lymphoma who relapsed following a response to I-131 tositumomab.A prior response > or = 3 months to I-131 tositumomab was required. The single therapeutic dose following a dosimetric dose was adjusted to give the same total body dose (in Gy) as that used for the original dose, or was attenuated if the platelet count was less than 150,000 per mm(3) or if the prior treatment resulted in grade 4 cytopenias lasting longer than 7 days.Of 32 patients enrolled, 28 completed the therapeutic dose. A median of four therapies were given before re-treatment. Eighteen (56%) of 32 patients had a complete or partial response (median duration, 15.2 months); eight (25%) had a complete response (median duration, 35 months). Five continue in response from 1.8 to 5.7 years, with a median follow-up of 35 months. The overall median response duration was not significantly different for the two treatments, with no clinical factors predicting response or its duration. Ten of 18 re-responders had longer responses with re-treatment, with five having responses > or = 1.5 years longer. Grade 3/4 neutropenia and thrombocytopenia occurred in 50% and 43% of patients, respectively, similar to initial treatment. Antimouse antibodies developed in 10% of patients, and 12% developed elevated serum thyroid-stimulating hormone. Six patients were diagnosed with second malignancies, including four patients who developed myelodysplastic syndrome (one who had not received the therapeutic dose) and one with acute myelogenous leukemia.Re-treatment with I-131 tositumomab following a previous response can produce second responses that can be durable.
View details for DOI 10.1200/JCO.2005.01.0892
View details for Web of Science ID 000233066700033
View details for PubMedID 16204016
Tositumomab and iodine-131 tositumomab produces durable complete remissions in a subset of heavily pretreated patients with low-grade and transformed non-Hodgkin's lymphomas
JOURNAL OF CLINICAL ONCOLOGY
2005; 23 (30): 7565-7573
This study is an integrated efficacy analysis of the five clinical trials of tositumomab and iodine-131 tositumomab in patients with relapsed or refractory low-grade, follicular, or transformed low-grade non-Hodgkin's lymphoma (NHL) that resulted in the regulatory approval of the iodine-131 tositumomab by the US Food and Drug Administration.This integrated analysis included 250 patients. Patients received a single course of iodine-131 tositumomab. Responses were assessed by an independent panel of radiologists and oncologists.Response rates in the five trials ranged from 47% to 68%; complete response rates ranged from 20% to 38%. With a median follow-up of 5.3 years, the 5-year progression-free survival was 17%. Eighty-one (32%) of 250 patients had a time to progression of > or = 1 year (termed durable response population). For the durable response population, 44% had not progressed at > or = 2.5 to > or = 9.5 years and had a median duration of response of 45.8 months. The median duration of complete response was not reached. The durable response population had many poor prognostic characteristics, including bone marrow involvement (41%), bulky disease > or = 5 cm (49%), and transformed histology (23%). Forty-three percent of the patients had been treated with more than four prior therapies and 36% had not responded to their most recent therapy.The tositumomab and iodine-131 tositumomab therapeutic regimen produces high response rates in patients with relapsed or refractory low-grade, follicular, and transformed low-grade NHL, with a sizable subgroup of patients achieving long-term durable responses.
View details for DOI 10.1200/JCO.2004.00.9217
View details for Web of Science ID 000232935300030
View details for PubMedID 16186600
Assessment of treatment-related myelodysplastic syndromes and acute myeloid leukemia in patients with non-Hodgkin lymphoma treated with tositumomab and iodine I-131 tositumomab
2005; 105 (12): 4576-4582
The incidence of treatment-related myelodysplastic syndromes and acute myeloid leukemia (tMDSs/tAML) after tositumomab and iodine I(131) tositumomab administration to previously treated and untreated patients with non-Hodgkin lymphoma (NHL) was evaluated. A total of 1071 patients were enrolled in 7 studies: 995 with relapsed/refractory low-grade NHL, +/- transformation (median, 3 prior regimens [range, 1-13 regimens]) and 76 patients with previously untreated low-grade follicular NHL. A single dose of iodine tositumomab and I(131) tositumomab was administered. For tMDS/tAML patients, baseline and posttherapy peripheral blood and marrow specimens were reviewed in a blinded fashion. Median follow-up was 6 years from diagnosis and 2 years from radioimmunotherapy (RIT) for previously treated patients, and 4.6 years from radioimmunotherapy for previously untreated patients. tMDS/tAML was reported in 35 (3.5%) of 995 patients (annualized incidence, 1.6%/y [95% confidence interval, 1.0%-2.0%/y]), and 52% of the tMDS/tAML diagnoses of tMDS/tAML were confirmed in a blinded review (annualized incidence of 1.1%/y [95% confidence interval, 0.7%-1.6%/y]). Of the 25 cases, 10 patients (40%) were diagnosed with tMDS/tAML prior to receiving radioimmunotherapy; 2 (8%) had no pathologic or clinical evidence to support such a diagnosis; and 13 (52%) were confirmed to have developed tMDS/tAML following RIT. This incidence is consistent with that expected on the basis of patients' prior chemotherapy for NHL. With a median follow-up approaching 5 years, no case of tMDS/tAML has been reported in any of the 76 patients receiving iodine I(131) tositumomab as their initial therapy (P = .011 compared with previously treated patients).
View details for DOI 10.1182/blood-2004-12-4690
View details for Web of Science ID 000229757300016
View details for PubMedID 15731177
Redox modulation of human prostate carcinoma cells by selenite increases radiation-induced cell killing
FREE RADICAL BIOLOGY AND MEDICINE
2005; 38 (1): 50-57
Although selenium compounds have been extensively studied as chemopreventative agents for prostate cancer, little is known about the potential use of selenium compounds for chemotherapy. We have shown that selenite inhibits cell growth and induces apoptosis in androgen-dependent LAPC-4 prostate cancer cells. LAPC-4 cells were more sensitive to selenite-induced apoptosis than primary cultures of normal prostate cells. Selenite-induced apoptosis in LAPC-4 cells correlated with a decrease in the Bcl-2:Bax expression ratio. Selenite-induced oxidative stress and apoptosis are dependent upon its reaction with reduced GSH. LAPC-4 cells treated with selenite showed decreased levels of total GSH and increased concentrations of GSSG. Thus, selenite altered the intracellular redox status toward an oxidative state by decreasing the ratio of GSH:GSSG. Because increased levels of Bcl-2 and GSH are associated with radioresistance, we examined the ability of selenite to sensitize prostate cancer cells to gamma-irradiation. Both LAPC-4 and androgen-independent DU 145 cells pretreated with selenite showed increased sensitivity to gamma-irradiation as measured by clonogenic survival assays. Importantly, selenite-induced radiosensitization was observed in combination with a clinically relevant dose of 2 Gy. These data suggest that altering the redox environment of prostate cancer cells with selenite increases the apoptotic potential and sensitizes them to radiation-induced cell killing.
View details for DOI 10.1016/j.freeradbiomed.2004.09.022
View details for Web of Science ID 000226172900006
View details for PubMedID 15589371
Darbepoietin alfa potentiates the efficacy of radiation therapy in mice with corrected or uncorrected anemia
2005; 65 (1): 284-290
Darbepoietin alfa (DA) is a long-acting analogue of erythropoietin that has reduced receptor affinity and enhanced biological activity. Experiments were done to test the hypothesis that correction of anemia in tumor-bearing mice by DA would increase tumor oxygenation and potentiate radiation-induced tumor cell killing. A SCC VII tumor model was used to study tumor responses to fractionated radiation therapy in mice with anemia induced by total body irradiation. Administration of DA reduced the extent and duration of anemia and associated tumor hypoxia, protected the bone marrow cells and prevented the body weight loss from the effect of irradiation, and facilitated the recovery in a time-dependent manner, with the administration of DA prior to total body irradiation having the greatest protective effect. When combined with fractionated radiation therapy, DA increased the tumor growth delay time from 2.7 days for irradiation alone to 7.3 to 10.6 days for combination of DA and irradiation. The effect of DA on tumor responses to fractionated radiation therapy was observed when DA was given 18 to 4 days before starting radiation therapy, but DA was also equally effective as a radiosensitizer when given only 2 hours before fractionated irradiation therapy. Weekly dosing of DA was as efficacious for the enhancement of radiation responses of tumors as biweekly dosing. Similar results were obtained in the RIF-1 fibrosarcoma tumor model. These studies show that DA can effectively correct anemia in tumor-bearing mice and sensitize tumor cells to fractionated radiation therapy. Importantly, DA was also able to sensitize tumors to radiation in mice with uncorrected anemia and hypoxia, suggesting that the effect of DA on radiosensitivity was independent of these factors and a different mechanism of action may be responsible for this effect.
View details for Web of Science ID 000226080200035
View details for PubMedID 15665305
The radioisotope contributes significantly to the activity of radioimmunotherapy
CLINICAL CANCER RESEARCH
2004; 10 (23): 7792-7798
A multicenter, randomized study was undertaken to estimate the single agent activity of Tositumomab and to determine the contribution of radioisotope-labeling with (131)I to activity and toxicity by comparing treatment outcomes for Tositumomab and Iodine I 131 Tositumomab (BEXXAR) to an equivalent total dose of unlabeled Tositumomab.Seventy-eight patients with refractory/relapsed non-Hodgkin's lymphoma were randomized to either unlabeled Tositumomab or Iodine I 131 Tositumomab. Patients progressing after unlabeled Tositumomab could cross over to receive Iodine I 131 Tositumomab. The median follow-up at analysis was 42.6 months (range 1.9 to 71.5 months).Responses in the Iodine I 131 Tositumomab versus unlabeled Tositumomab groups: overall response 55% versus 19% (P = 0.002); complete response 33% versus 8% (P = 0.012); median duration of overall response not reached versus 28.1 months (95% confidence interval: 7.6, not reached); median duration of complete response not reached in either arm; and median TTP 6.3 versus 5.5 months (P = 0.031), respectively. Of the patients who had a complete response after initial Iodine I 131 Tositumomab therapy, 71% (10 of 14) continued in complete response at 29.8 to 71.1 months. Two patients who achieved a complete response after unlabeled Tositumomab had ongoing responses at 48.1 to 56.9 months. Nineteen patients received Iodine I 131 Tositumomab crossover therapy. Responses after crossover versus prior response to unlabeled Tositumomab were as follows: complete response rates of 42% versus 0% (P = 0.008); overall response 68% versus 16% (P = 0.002); median durations of overall response 12.6 versus 7.6 months (P = 0.001); and median TTP 12.4 versus 5.5 months (P = 0.01), respectively. Hematologic toxicity was more severe and nonhematologic adverse events were more frequent after Iodine I 131 Tositumomab than after Tositumomab alone. Elevated thyrotropin occurred in 5% of patients. Seroconversion to human antimurine antibody after Iodine I 131 Tositumomab, unlabeled Tositumomab, and Iodine I 131 Tositumomab-crossover was 27%, 19%, and 0%, respectively.Unlabeled Tositumomab showed single agent activity, but in this direct comparison, all of the therapeutic outcome measures were significantly enhanced by the conjugation of (131)I to Tositumomab.
View details for Web of Science ID 000225673200002
View details for PubMedID 15585610
Enhancement of the efficacy of an antagonist of an extracellular receptor by attachment to the surface of a biocompatible carrier
2004; 21 (10): 1880-1885
In order to improve the in vitro and in vivo efficacy of an integrin antagonist (IA) of the extracellular domain of the alphavbeta3 integrin, a receptor upregulated on tumor neovasculature, the IA was attached to the surface of a dextran-coated liposome (DCL). IA-DCLs were characterized in vitro, and the pharmacokinetic and antitumor properties were assessed in vivo.The in vitro binding properties were measured with purified integrin, endothelial cells, and melanoma cells. The pharmacokinetic parameters were measured in healthy mice with 14C-labeled IA-DCLs and anti-tumor efficacy was assessed with the M21 human melanoma xenograft mouse model.In vitro, IC50 values for IA-DCLs and IA are similar, and IA-DCLs inhibit cell proliferation relative to controls. IA-DCLs are stable in serum, and the pharmacokinetic half-life in mice is 23 h. In the M21/mouse model, statistically significant inhibition of tumor growth was observed for mice treated with IA-DCLs, whereas controls including saline, DCLs lacking IA, and cyclo(RGDfV) were ineffective. Increased apoptosis and a reduction in vessel counts relative to controls were present in tumors from animals treated with IA-DCLs.These results demonstrate that IA-DCLs are potent anti-angiogenic therapeutic agents with superior in vivo activity and pharmacology compared to unmodified IA.
View details for Web of Science ID 000224532900022
View details for PubMedID 15553236
Increased cure rate of glioblastoma using concurrent therapy with radiotherapy and arsenic trioxide
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
2004; 60 (1): 197-203
Patients with glioblastoma multiforme (GBM) do extremely poorly despite aggressive therapy with surgery, radiotherapy (RT), and chemotherapy. In an effort to increase the efficacy of therapy for GBM, we studied the efficacy of arsenic trioxide (ATO) combined with high-dose RT in GBM cells in vitro and GBM xenograft tumors in nude mice.Human glioblastoma cell line SNB75 cells were irradiated in vitro with doses of 0-15 Gy with or without ATO. Clonogenic assays were used to generate radiation survival curves. Intracellular reactive oxygen species and apoptosis induced by ATO and RT were measured. The therapeutic efficacy of ATO alone, local tumor RT alone, and the combined therapy was tested in nude mice bearing established s.c. SNB75 tumors. A single RT dose of 20 Gy was administered locally to tumors. ATO at 10 mg/kg was injected i.p. 10 min after RT for the in vivo experiments.Radiation survival curves of GBM SNB75 cells demonstrated that a dose of 0.2 microM ATO increased radiation-induced cell killing by 2 logs at 10 Gy. ATO at 1 microM decreased survival from 4 x 10(-2) after 7 Gy of RT alone to 4 x 10(-5). A time-course experiment demonstrated that the greatest level of cell killing occurred when ATO was administered immediately before or within 2 hours after RT. To test the therapeutic efficacy of this combined treatment regimen in vivo, nude mice with established SNB75 GBM tumors were treated with a single local tumor dose of 20 Gy of RT with or without ATO (10 mg/kg x two doses) administered weekly. Appropriate control groups were included as well. ATO alone did not inhibit tumor growth. RT at 20 Gy alone inhibited tumor growth by 45 days, with regrowth of tumors thereafter. The combination of RT and ATO resulted in complete regression of the tumors in 4 of 5 mice without tumor regrowth for up to 4 months. The fifth mouse in the combined treatment group had a 90% reduction in tumor size without progression during the 4-month follow-up period. Furthermore, ATO alone and in combination with RT did not produce any obvious signs of toxicity.These results have demonstrated that ATO increases intracellular levels of reactive oxygen species, induces apoptosis, and enhances the radiation cell killing of GBM cells. RT combined with ATO was an effective treatment for GBM tumors in this preclinical model. These preclinical results are encouraging and provide a rationale for further study of ATO combined with RT for the treatment of GBM and other histologic types of brain cancer using a variety of RT schemes.
View details for DOI 10.1016/j.ijrobp.2004.02.013
View details for Web of Science ID 000223854500025
View details for PubMedID 15337556
Enhanced effectiveness of radiochemotherapy with tirapazamine by local application of electric pulses to tumors
2004; 162 (2): 185-193
Tumor hypoxia is associated with resistance to radiotherapy and anticancer chemotherapy. However, it can be exploited to therapeutic advantage by concomitantly using hypoxic cytotoxins, such as tirapazamine (TPZ). Tumor electroporation offers the means to further increase tumor hypoxia by temporarily reducing tumor blood flow and therefore increase the cytotoxicity of TPZ. The primary objective of this work was to determine whether electric pulses combined with TPZ and radiotherapy (electroradiochemotherapy) was more efficacious than radiochemotherapy (TPZ + radiation). In these studies using the SCCVII tumor model in C3H mice, electroradiochemotherapy produced up to sixfold more tumor growth delay (TGD) than TPZ + radiation. In these studies, (1) large tumors (280 +/- 15 mm3) responded better to electroradiochemotherapy than small tumors (110 +/- 10 mm3), (2) TGD correlated linearly with tumor volume at the time of electroradiochemotherapy, (3) electric pulses induced a rapid but reversible reduction in O2 saturation, and (4) the electric field was highest near the periphery of the tumor in a 3D computer model. The findings suggested that electroradiochemotherapy gained its therapeutic advantage over TPZ + radiation by enhancing the cytotoxic action of TPZ through reduced tumor oxygenation. The greater antitumor effect achieved in large tumors may be related to tumor morphology and the electric-field distribution. These results suggest that electro-pulsation of large solid tumors may be of benefit to patients treated with radiation in combination with agents that kill hypoxic cells.
View details for Web of Science ID 000223159500011
View details for PubMedID 15387146
Radiobiology of radioimmunotherapy: Targeting CD20 B-cell antigen in non-Hodgkin's lymphoma
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
2004; 59 (5): 1274-1287
The radiobiology of radioimmunotherapy is an important determinant of both the toxicity and the efficacy associated with the treatment of B-cell non-Hodgkin's lymphoma with radiolabeled anti-CD20 monoclonal antibodies. The properties of the target, CD20, and the mechanisms of action of both the monoclonal antibodies and the associated exponentially decreasing low-dose-rate radiotherapy are described. The radiation dose and dose-rate effects are discussed and related to both the tumor responses and normal organ toxicity. Finally, the use of either unlabeled or radiolabeled anti-CD20 monoclonal antibodies as a component of combined modality therapy (including the sequential or concurrent use of sensitizers) and future directions of the field are discussed.
View details for DOI 10.1016/j.ijrobp.2004.02.065
View details for Web of Science ID 000222932800003
View details for PubMedID 15275710
Phase I study of I-131-chimeric(ch) TNT-1/B antibody for the treatment of advanced colorectal cancer
10th Conference on Cancer Therapy with Antibodies and Immunoconjugates
MARY ANN LIEBERT INC. 2004: 528–28
View details for Web of Science ID 000224115300050
Phase 1 trial of a novel anti-CD20 fusion protein in pretargeted radioimmunotherapy for B-cell non-Hodgkin lymphoma
2004; 104 (1): 227-236
Pretargeted radioimmunotherapy (PRIT) has the potential to increase the dose of radionuclide delivered to tumors while limiting radiation to normal tissues. The purpose of this phase 1 trial is to assess safety of this multistep approach using a novel tetrameric single-chain anti-CD20-streptavidin fusion protein (B9E9FP) as the targeting moiety in patients with B-cell non-Hodgkin lymphoma (NHL), and to characterize its pharmacokinetics and immunogenicity. All patients received B9E9FP (160 mg/m(2) or 320 mg/m(2)); either 48 or 72 hours later, a synthetic clearing agent (sCA) was administered (45 mg/m(2)) to remove circulating unbound B9E9FP. (90)Yttrium ((90)Y; 15 mCi/m(2))/(111)In (5 mCi)-DOTA-biotin was injected 24 hours later. There were 15 patients enrolled in the study. B9E9FP had a mean plasma half-life (T(1/2)) of 25 +/- 6 hours with a reduction in plasma level of more than 95% within 6 hours of sCA administration. (90)Y/(111)In-DOTA-biotin infusion resulted in rapid tumor localization and urinary excretion. The ratio of average tumor to whole-body radiation dose was 49:1. No significant hematologic toxicities were noted in 12 patients. There were 2 patients who had hematologic toxicity related to progressive disease. There were 2 complete remissions (90 and 325 days) and one partial response (297 days). B9E9FP performs well as the targeting component of PRIT with encouraging dosimetry, safety, and efficacy. A dose escalation trial of (90)Y-DOTA-biotin in this format is warranted.
View details for DOI 10.1182/blood-2003-09-3284
View details for Web of Science ID 000222307500042
View details for PubMedID 14996706
Dosimetry model for radioactivity localized to intestinal mucosa
CANCER BIOTHERAPY AND RADIOPHARMACEUTICALS
2004; 19 (3): 293-307
This paper provides a new model for calculating radiation-absorbed doses to the full thickness of the small and large intestinal walls, and to the mucosal layers. The model was used to estimate the intestinal radiation doses from yttrium-90-labeled-DOTA-biotin binding to NR-LU-10-streptavidin in patients.We selected model parameters from published data and observations, and used the model to calculate energy-absorbed fractions using the EGS4 radiation transport code. We determined the cumulated (90)Y activity in the small and large intestines of patients from gamma camera images, and calculated absorbed doses to the mucosal layer and to the whole intestinal wall.The mean absorbed dose to the wall of the small intestine was 16.2 mGy/MBq (60 cGy/mCi) administered from (90)Y localized in the mucosa, and 70 mGy/MBq (260 cGy/mCi) to the mucosal layer within the wall. Doses to the large intestinal wall and to the mucosa of the large intestine were lower than those for the small intestine by a factor of about 2.5. These doses are greater by factors of about 5 to 6 than those that would have been calculated using the standard MIRD models that assume the intestinal activity is in the bowel contents.The specific uptake of radiopharmaceuticals in mucosal tissues may lead to dose-related intestinal toxicities. Tissue dosimetry at the sub-organ level is useful for a better understanding of intestinal tract radiotoxicity and associated dose-response relationships.
View details for Web of Science ID 000222672600004
View details for PubMedID 15285876
A novel antiangiogenesis therapy using an integrin antagonist or anti-FLK-1 antibody coated Y-90-labeled nanoparticles
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
2004; 58 (4): 1215-1227
Integrin alpha(v)beta(3) and vascular endothelial growth factor receptor 2 (Flk-1) have been shown to be involved in tumor-induced angiogenesis. Selective targeting of upregulated alpha(v)beta(3) and Flk-1 on the neovasculature of tumors is a novel antiangiogenesis strategy for treating a wide variety of solid tumors. In the studies described here, we investigated the potential therapeutic efficacy of two three-component treatment regimens using two murine tumor models.The treatment regimens used nanoparticle (NP) based targeting agents radiolabeled with (90)Y. The small molecule integrin antagonist (IA) 4-[2-(3,4,5,6-tetrahydropyrimidin-2-ylamino)ethoxy]-benzoyl-2-(5)-aminoethylsulfonylamino-beta-alanine, which binds to the integrin alpha(v)beta(3), and a monoclonal antibody against murine Flk-1 (anti-Flk-1 MAb) were used to target the NPs. Murine tumor models K1735-M2 (melanoma) and CT-26 (colon adenocarcinoma) were used to evaluate the treatment efficacy.In K1735-M2 and CT-26 tumors, a single treatment with IA-NP-(90)Y (14.2 microg/g IA, 5 or 6 microCi/g (90)Y) caused a significant tumor growth delay compared to untreated control tumors, as well as tumors treated with IA, IA-NP, and NP-(90)Y, respectively (p < 0.025, Wilcoxon test). In K1735-M2 tumors, a single treatment with anti-Flk-1 MAb-NP-(90)Y (0.36 microg/g anti-Flk-1 MAb, 5 microCi/g (90)Y) also caused a significant tumor growth delay (p < 0.05, Wilcoxon test) compared to untreated tumors, as well as tumors treated with anti-Flk-1 MAb, anti-Flk-1 MAb-NP, and conventional radioimmunotherapy with (90)Y-labeled anti-Flk mAb. Anti-CD31 staining showed a marked decrease in vessel density in tumors treated with anti-Flk-1 MAb-NP-(90)Y, which was associated with a high level of apoptotic death in these tumors, as shown by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining.The present studies provide proof of principle that targeted radiotherapy works using different targeting agents on a nanoparticle, to target both the integrin alpha(v)beta(3) and the vascular endothelial growth factor receptor. These encouraging results demonstrate the potential therapeutic efficacy of the IA-NP-(90)Y and anti-Flk-1 MAb-NP-(90)Y complexes as novel therapeutic agents for the treatment of a variety of tumor types.
View details for DOI 10.1016/j.ijrob.2003.10.057
View details for Web of Science ID 000220084200027
View details for PubMedID 15001266
HuMax-CD4, fully human monoclonal antibody: Phase II trial in cutaneous T cell lymphoma
65th Annual Meeting of the Society-for-Investigative-Dermatology
NATURE PUBLISHING GROUP. 2004: A57–A57
View details for Web of Science ID 000220660500392
Radiobiology of radioimmunotherapy with Y-90 ibritumomab tiuxetan (Zevalin)
SEMINARS IN ONCOLOGY
2003; 30 (6): 6-10
Radioimmunotherapy represents a significant advance over unlabeled immunotherapy for the treatment of patients with B-cell non-Hodgkin's lymphoma. The efficacy of radioimmunotherapeutic agents depends in large part on the basic biological effects associated with their components, monoclonal antibodies and radionuclides, separately and in combination. The radiobiological effects associated with yttrium 90-labeled ibritumomab tiuxetan (Zevalin; Biogen Idec Inc, Cambridge, MA) include the induction of apoptosis and cell-cycle redistribution (eg, arrest of cells in the G(2)/M phase of the cell cycle). Because of dose-rate effects, tumor cells may, in some cases, be more susceptible to the low-dose-rate radiation used in radioimmunotherapy than to the high-dose-rate radiation used in external beam radiotherapy. The efficacy of radioimmunotherapy may potentially be optimized through a variety of approaches, including the use of agents that increase the expression of certain tumor antigens (thus facilitating improved biodistribution of radiolabeled monoclonal antibodies) or that sensitize tumor cells to radiation.
View details for DOI 10.1053/j.seminoncol.2003.10.005
View details for Web of Science ID 000187880300002
View details for PubMedID 14710397
Radiation-induced cyclooxygenase 2 up-regulation is dependent on redox status in prostate cancer cells
2003; 160 (6): 617-621
Cyclooxygenase 2 (COX2) is the inducible isozyme of COX, a key enzyme in arachidonate metabolism and the conversion of arachidonic acid (AA) to prostaglandins (PGs) and other eicosanoids. Previous studies have demonstrated that the COX2 protein is up-regulated in prostate cancer cells after irradiation and that this results in elevated levels of PGE(2). In the present study, we further investigated whether radiation-induced COX2 up-regulation is dependent on the redox status of cells from the prostate cancer cell line PC-3. l-Buthionine sulfoximine (BSO), which inhibits gamma glutamyl cysteine synthetase (gammaGCS), and the antioxidants alpha-lipoic acid and N-acetyl-l-cysteine (NAC) were used to modulate the cellular redox status. BSO decreased the cellular GSH level and increased cellular reactive oxygen species (ROS) in PC-3 cells, whereas alpha-lipoic acid and NAC increased the GSH level and decreased cellular ROS. Both radiation and the oxidant H(2)O(2) had similar effects on COX2 up-regulation and PGE(2) production in PC-3 cells, suggesting that radiation-induced COX2 up-regulation is secondary to the production of ROS. The relative increases in COX2 expression and PGE(2) production induced by radiation and H(2)O(2) were even greater when PC-3 cells were pretreated with BSO. When the cells were pretreated with alpha-lipoic acid or NAC for 24 h, both radiation- and H(2)O(2)-induced COX2 up-regulation and PGE(2) production were markedly inhibited. These results demonstrate that radiation-induced COX2 up-regulation in prostate cancer cells is modulated by the cellular redox status. Radiation-induced increases in ROS levels contribute to the adaptive response of PC-3 cells, resulting in elevated levels of COX2.
View details for Web of Science ID 000187079200001
View details for PubMedID 14640786
Long-term results of a randomized trial comparing Tositumomab and Iodine-131 Tositumomab (BEXXAR (R)) with Tositumomab alone in patients with relapsed or refractory low-grade (LG) or transformed low grade (T-LG) Non-Hodgkin's Lymphoma (NHL).
45th Annual Meeting and Exhibition of the American-Society-of-Hematology
AMER SOC HEMATOLOGY. 2003: 405A–406A
View details for Web of Science ID 000186536701474
Higher doses of Rituxan (R) alter pharmacokinetics and biodistribution of Zevalin (R) but may increase responses; a preliminary report of a phase I study of Zevalin (R) using a modified treatment regimen for relapsed or refractory CD20+B-cell follicular/transformed non-Hodgkin's lymphoma.
45th Annual Meeting and Exhibition of the American-Society-of-Hematology
AMER SOC HEMATOLOGY. 2003: 408A–408A
View details for Web of Science ID 000186536701483
Cell surface receptor-targeted dextran-coated liposomes for the treatment of solid tumors.
226th National Meeting of the American-Chemical-Society
AMER CHEMICAL SOC. 2003: U468–U468
View details for Web of Science ID 000187062502402
Distribution of monoclonal antiferritin antibody in Kaposi's sarcoma, Hodgkin's disease, and hepatocellular carcinoma
2003; 34 (4): 381-384
The immunotherapeutic treatment of cancers using antibodies (naked or conjugated to a drug, toxin, or radionuclide) relies upon the preferential expression of a targeted antigen on the cancer cell compared to normal tissues. Polyclonal antiferritin antisera have shown selective distribution and therapeutic efficacy when radiolabeled in Hodgkin's disease and hepatoma. In this immunohistochemical study, we investigated the distribution of ferritin in tumors from 6 patients with Kaposi's sarcoma, 12 patients with Hodkgin's disease, and 9 patients with hepatoma, as well as in selected normal tissues. We found that the monoclonal antiferritin antibody binds primarily to histiocytes in samples from Kaposi's sarcoma and Hodgkin's disease. One hepatocellular carcinoma showed diffuse cytoplasmic staining with ferritin. Deposition of the monoclonal antibody was not detectable in the remaining hepatocellular carcinoma samples.
View details for DOI 10.1053/hupa.2003.62
View details for Web of Science ID 000182556800014
View details for PubMedID 12733120
Pretarget radioimmunotherapy (RIT) with anti-CD20 fusion protein in patients with non-Hodgkin's lymphoma (NHL).
SOC NUCLEAR MEDICINE INC. 2002: 116P–117P
View details for Web of Science ID 000175560800420
Synthesis of multivalent nanoparticles for use in targeting vascular receptors.
AMER CHEMICAL SOC. 2002: A109–A109
View details for Web of Science ID 000176296800640
Role of glutathione depletion and reactive oxygen species generation in apoptotic signaling in a human B lymphoma cell line
CELL DEATH AND DIFFERENTIATION
2002; 9 (3): 252-263
The primary objective of this study was to determine the sequence of biochemical signaling events that occur after modulation of the cellular redox state in the B cell lymphoma line, PW, with emphasis on the role of mitochondrial signaling. L-Buthionine sulphoximine (BSO), which inhibits gamma glutamyl cysteine synthetase (gammaGCS), was used to modulate the cellular redox status. The sequence and role of mitochondrial events and downstream apoptotic signals and mediators was studied. After BSO treatment, there was an early decline in cellular glutathione (GSH), followed by an increase in reactive oxygen species (ROS) production, which induced a variety of apoptotic signals (detectable at different time points) in the absence of any external apoptotic stimuli. The sequence of biochemical events accompanying apoptosis included a 95% decrease in total GSH and a partial (25%) preservation of mitochondrial GSH, without a significant increase in ROS production at 24h. Early activation and nuclear translocation of the nuclear factor kappa B subunit Rel A was observed at approximately 3h after BSO treatment. Cytochrome c release into the cytosol was also seen after 24h of BSO treatment. p53 protein expression was unchanged after redox modulation for up to 72 h, and p21waf1 independent loss of cellular proliferation was observed. Surprisingly, a truncated form of p53 was expressed in a time-dependent manner, beginning at 24h after BSO incubation. Irreversible commitment to apoptosis occurred between 48 and 72 h after BSO treatment when mitochondrial GSH was depleted, and there was an increase in ROS production. Procaspase 3 protein levels showed a time-dependent reduction following incubation with BSO, notably after 48 h, that corresponded with increasing ROS levels. At 96 h, caspase 3 cleavage products were detectable. The pan-caspase inhibitor zVADfmk, partially blocked the induction of apoptosis at 48 h, and was ineffective after 72 h. PW cells could be rescued from apoptosis by removing them from BSO after up to 48, but not 72 h incubation with BSO. Mitochondrial transmembrane potential (DeltaPsi(m)) remained intact in most of the cells during the 72 h observation period, indicating that DeltaPsi(m) dissipation is not an early signal for the induction of redox dependent apoptosis in PW cells. These data suggest that a decrease in GSH alone can act as a potent early activator of apoptotic signaling. Increased ROS production following mitochondrial GSH depletion, represents a crucial event, which irreversibly commits PW cells to apoptosis.
View details for DOI 10.1038/sj.cdd.4400959
View details for Web of Science ID 000174032600006
View details for PubMedID 11859408
The antiangiogenic agents SU5416 and SU6668 increase the antitumor effects of fractionated irradiation
2002; 157 (1): 45-51
Angiogenesis is critical for tumor development, growth and metastasis. The vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and platelet-derived growth factor (PDGF) and their tyrosine kinase receptors are major regulators of angiogenesis. Radiation induces the production of VEGF, FGF and PDGF in many tumor cells. We hypothesized that inhibition of the function of these growth factors could inhibit tumor angiogenesis and thereby enhance the efficacy of radiation therapy. To test this hypothesis, we used the small molecule inhibitors SU5416 (an inhibitor for Vegf receptor) and SU6668 (an inhibitor for Vegf, Fgf and Pdgf receptors) alone and in combination with fractionated irradiation to treat C3H mice bearing SCC VII carcinomas. The SCC VII tumors express Vegf, Fgf2 (also known as bFGF), Pdgf and their associated receptors. Animals were given either SU5416 or SU6668 daily before or after irradiation (2 Gy per fraction per day for 5 days). The results from these experiments demonstrate that administration of either SU5416 or SU6668 without radiation delayed tumor growth. Administration of SU5416 at a dose of 25 mg/kg per day (the maximum tolerated effective dose) inhibited tumor growth by 17.9% on day 7 (P < 0.05 compared to untreated control mice) and produced an average tumor growth delay time of 0.5-2.0 days. When combined with fractionated irradiation, administration of SU5416 increased the inhibition of tumor growth to 50-53% on day 7 and the tumor growth delay time to 5.7-6.5 days (P < 0.001 compared with SU5416 alone; P < or = 0.05 compared with radiation alone). SU6668 alone inhibited tumor growth in a dose-dependent manner. Administration of SU6668 at a dose of 75 mg/kg per day (a suboptimal dose) inhibited tumor growth by 36% on day 7 and produced an average tumor growth delay time of 3.3 +/- 1.4 days. The combination of SU6668 with fractionated radiation increased inhibition of tumor growth to 66-70% and the tumor growth delay time from 3.3 days to 11.9 days (P < or = 0.001 compared with either radiation alone or SU6668 alone). Administration of these agents before or after irradiation produced similar results (P = 0.40 for SU5416; P = 0.98 for SU6668). SU5416 or SU6668 alone or in combination with radiation was very well tolerated with little or no toxicity. These results suggest that inhibition of Vegf, Fgf and Pdgf receptor function by SU5416 and SU6668 can enhance the efficacy of irradiation. The targeting of multiple tyrosine kinase receptors by SU6668 is more effective than inhibition of the Vegf receptor alone by SU5416 for the enhancement of tumor cell killing by fractionated irradiation.
View details for Web of Science ID 000173150300008
View details for PubMedID 11754641
Rotenone-induced G2/M cell cycle arrest and apoptosis in a human B lymphoma cell line PW
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
2001; 289 (5): 973-978
Concentrations of rotenone (ROT) that block electron flow through mitochondrial complex I (100 nM) did not significantly alter either cell viability or the growth of PW cells. However, 10- to 50-fold higher concentrations (1-5 microM) were found to induce a dose-dependent cell cycle arrest predominantly at the G2/M stage of the cycle and apoptosis. Apoptosis was dependent on the cell cycle arrest, since apoptosis but not the G2/M arrest was prevented with the broad spectrum caspase inhibitor zVADfmk. Biochemical features of apoptosis included mitochondrial cytochrome c release, reactive oxygen species generation, and the activation of procaspase 3. Thus, ROT inhibition of mitochondrial electron transport may be insufficient to induce apoptosis in PW cells. Instead, apoptosis in these cells occurs as a consequence of disruption of the cell cycle and is only indirectly dependent upon mitochondrial electron transport.
View details for DOI 10.1006/bbrc.2001.6054
View details for Web of Science ID 000173406500010
View details for PubMedID 11741286
Radioimmunotherapy of B-cell NHL.
Current pharmaceutical biotechnology
2001; 2 (4): 327-339
Much progress has been made in the development and implementation of radionuclide-carrying antibody therapy (radioimmunotherapy or RIT) of non-Hodgkin's lymphomas (NHL) in the past decade. Response rates have generally exceeded 60% for nonmyeloablative single dose RIT (85% - 100% for myeloablative) in patients who have relapsed after primary therapy. It is also encouraging that the duration of such responses has often been greater than the response to the last chemotherapeutic regimen administered. These results, as well as a favorable toxicity profile, have resulted in the successful earlier and more widespread use of this new therapeutic modality. Although unlabeled antibody therapy alone has had a positive impact on the treatment of NHL, the response rates for RIT have been higher than (sometimes nearly double) those for unlabeled antibody therapy. This has been demonstrated in trials that have directly compared radiolabeled antibody with unlabeled antibody, as well as in separate trials for similar patient groups. Use of radionuclides in conjunction with antibodies adds transient marrow suppression and a small risk of second malignancy over unlabeled antibody therapy. However, the toxicity from a single course of RIT is very favorable compared to chemotherapy. Despite the enormous progress of RIT, much remains to be learned to fully optimize the role of this exciting modality in the treatment of NHL.
View details for PubMedID 11762414
Pivotal study of iodine I 131 Tositumomab for chemotherapy-refractory low-grade or transformed low-grade B-cell non-Hodgkin's lymphomas
JOURNAL OF CLINICAL ONCOLOGY
2001; 19 (19): 3918-3928
To evaluate the efficacy and safety of tositumomab and iodine I 131 tositumomab (Bexxar; Corixa Corp, Seattle, WA, and GlaxoSmithKline, Philadelphia, PA) in patients with chemotherapy-refractory low-grade or transformed low-grade non-Hodgkin's lymphoma (NHL) and to compare its efficacy to the patients' last qualifying chemotherapy (LQC) regimens.Sixty patients who had been treated with at least two protocol-specified qualifying chemotherapy regimens and had not responded or progressed within 6 months after their LQC were treated with a single course of iodine I 131 tositumomab.Patients had received a median of four prior chemotherapy regimens. A partial or complete response (CR) was observed in 39 patients (65%) after iodine I 131 tositumomab, compared with 17 patients (28%) after their LQC (P <.001). The median duration of response (MDR) was 6.5 months after iodine I 131 tositumomab, compared with 3.4 months after the LQC (P <.001). Two patients (3%) had a CR after their LQC, compared with 12 (20%) after iodine I 131 tositumomab (P <.001). The MDR for CR was 6.1 months after the LQC and had not been reached with follow-up of more than 47 months after iodine I 131 tositumomab. An independent review panel verified that 32 (74%) of the 43 patients with nonequivalent durations of response (> 30 days difference) had a longer duration of response after iodine I 131 tositumomab (P <.001). Only one patient was hospitalized for neutropenic fever. Five patients (8%) developed human antimurine antibodies, and one (2%) developed an elevated TSH level after treatment. Myelodysplasia was diagnosed in four patients in follow-up.A single course of iodine I 131 tositumomab was significantly more efficacious than the LQC received by extensively pretreated patients with chemotherapy-refractory, low-grade, or transformed low-grade NHL and had an acceptable safety profile.
View details for Web of Science ID 000171246200004
View details for PubMedID 11579112
Bcl-2 inhibits apoptosis induced by mitochondrial uncoupling but does not prevent mitochondrial transmembrane depolarization
EXPERIMENTAL CELL RESEARCH
2001; 262 (2): 170-179
Bcl-2 overexpression protects cells from apoptosis induced by many cytotoxic agents. In this study, we investigated the effects of uncoupling mitochondrial electron transport in both HL60 wild-type and Bcl-2-overexpressing cells using the protonophore carbonyl cyanide m-chlorophenylhydrazone. We found that uncoupling mitochondrial electron transport induced apoptosis in wild-type, but not in Bcl-2-overexpressing cells. To investigate the mechanism of action of Bcl-2-mediated inhibition of cyanide m-chlorophenylhydrazone-induced apoptosis, we measured the mitochondrial transmembrane potential (DeltaPsi(m)) after uncoupling mitochondrial electron transport and found that both HL-60 wild-type and Bcl-2-overexpressing cells similarly depolarize following cyanide m-chlorophenylhydrazone exposure. Western blot analysis demonstrated that Bcl-2 overexpression did not completely block cytochrome c release from mitochondria after uncoupling mitochondrial electron transport. Since Bcl-2 may act as an antioxidant, we studied the effect of altering the cellular redox state prior to uncoupling mitochondrial electron transport in Bcl-2-overexpressing cells. Depletion of mitochondrial (but not cytosolic) glutathione induced apoptosis in Bcl-2-overexpressing cells and negated the protective effect of Bcl-2. Furthermore, following glutathione depletion, Bcl-2-overexpressing cells were sensitized to undergo cyanide m-chlorophenylhydrazone-induced apoptosis. These data suggest that the action of Bcl-2 is dependent, in part, on the cellular and mitochondrial redox state.
View details for Web of Science ID 000166516600011
View details for PubMedID 11139341
Long-term follow-up of patients with Stage III follicular lymphoma treated with primary radiotherapy at Stanford University
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
2001; 49 (1): 3-15
To report the long-term survival and late toxicity data of Stage III follicular lymphoma patients treated with primary radiotherapy.Sixty-six patients with Stage III follicular small cleaved (FSC) or follicular mixed (FM) non-Hodgkin's lymphoma were treated with total lymphoid irradiation (61 patients) or whole body irradiation (5 patients) as their primary treatment modality from 1963 to 1982 at Stanford University. Adjuvant chemotherapy was given to 13 patients.Median follow-up was 9.5 years with a range of 0.5-24.3 years. Median overall survival, cause-specific survival, freedom from relapse, and event-free survival were 9.5, 18.9, 7.1, and 5.1 years, respectively. Few initial relapses or lymphoma-related deaths were seen beyond the first decade of follow-up. Patient age and number of disease sites were the two strongest predictors of overall survival. The cohort of patients with limited Stage III disease demonstrated an 88% freedom from relapse and a 100% cause-specific survival with up to 23.5 years follow-up.The long-term survival data for Stage III FSC or FM non-Hodgkin's lymphoma treated with primary radiotherapy are at least comparable and possibly better than results achieved with other therapeutic approaches. Patients with limited Stage III disease do particularly well. Whether these results are superior to an initial approach of deferred therapy until clinically indicated is currently unknown.
View details for Web of Science ID 000166317300002
View details for PubMedID 11163492
Radiation induces upregulation of cyclooxygenase-2 (COX-2) protein in PC-3 cells
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
2000; 48 (2): 325-328
To investigate the impact of gamma-irradiation on cyclooxygenase-2 (COX-2) expression and its enzymatic activity in PC-3 cells. Cell cycle redistribution, viability, and apoptosis were quantitated in control and irradiated cells with or without the COX-2 inhibitor NS-398.Western blot analysis was used to assess COX-2 protein expression. Prostaglandin (PGE(2)) was measured after addition of arachidonic acid (AA) using a Monoclonal Immunoassay Kit. Cell cycle and apoptosis were assessed using flow cytometry.We observed a dose-dependent increase in COX-2 of 37.0%, 79.7%, and 97.5% following irradiation with 5, 10, and 15 Gy, respectively. The PGE(2) level of irradiated cells was higher than in controls (1512 +/- 157.5 vs. 973.7 +/- 54.2 rhog PGE(2)/mL; p < 0.005, n = 4) while cells irradiated in the presence of NS-398 had reduced PGE(2) levels (218.8 +/- 80.1 rhog PGE(2)/mL; p < 0.005; n = 4). We found no differences in cell cycle distribution or apoptosis between cells irradiated in the presence or absence of NS-398.COX-2 protein is upregulated and enzymatically active after irradiation, resulting in elevated levels of PGE(2). This effect can be suppressed by NS-398, which has clinical implications for therapies combining COX-2 inhibitors with radiation therapy.
View details for Web of Science ID 000089069100004
View details for PubMedID 10974444
Bcl-2 overexpression results in enhanced capacitative calcium entry and resistance to SKF-96395-induced apoptosis
2000; 60 (16): 4358-4361
Although there is evidence that changes in cellular ionic concentrations are important early events in apoptosis, the regulation of ion fluxes across the plasma membrane during this process is poorly understood. We report here that Bcl-2 overexpression results in up-regulation of capacitative Ca2+ entry (CCE) and that SKF-96365, an inhibitor of CCE, is a potent inducer of apoptosis. Cells that overexpress Bcl-2 are resistant to SKF-96365-mediated apoptosis and to its inhibition of CCE. Enhanced CCE can be reversed with ouabain, suggesting that Bcl-2-associated plasma membrane hyperpolarization plays a role in up-regulating CCE and may partially explain the antiapoptotic effect of Bcl-2.
View details for Web of Science ID 000088961100014
View details for PubMedID 10969777
SEMINARS IN RADIATION ONCOLOGY
2000; 10 (2): 73-93
Radioimmunotherapy (RIT) is a promising new therapy for the treatment of a variety of malignancies. General principles of RIT are discussed, including important considerations in the selection of monoclonal antibodies (MAb) and radionuclides for RIT. Results of clinical trials using RIT for the treatment of lymphoma, leukemia, and solid tumors are summarized. The results from many of these trials are promising, especially for the treatment of lymphohematopoietic malignancies, in which a variety of MAb, radionuclides, and study designs have resulted in high response rates with a number of durable responses. Encouraging results have also been obtained using RIT to treat some solid tumors, primarily in patients with relatively low tumor burdens. RIT is generally well tolerated, with the primary toxicity being transient reversible myelosuppression in most nonmyeloablative studies. Nonhematologic toxicity, especially at nonmyeloablative doses, has been minimal in most studies. Approaches for increasing the therapeutic index of RIT are reviewed, which may further potentiate the efficacy and decrease the toxicity of RIT.
View details for Web of Science ID 000086455600002
View details for PubMedID 10727597
Multicenter phase II study of iodine-131 tositumomab for chemotherapy-relapsed/refractory low-grade and transformed low-grade B-cell non-Hodgkin's lymphomas
JOURNAL OF CLINICAL ONCOLOGY
2000; 18 (6): 1316-1323
This multicenter phase II study evaluated the efficacy, dosimetry methodology, and safety of iodine-131 tositumomab in patients with chemotherapy-relapsed/refractory low-grade or transformed low-grade non-Hodgkin's lymphoma (NHL).Patients received a dosimetric dose that consisted of 450 mg of anti-B1 antibody followed by 35 mg (5 mCi) of iodine-131 tositumomab. Serial total-body gamma counts were then obtained to calculate the patient-specific millicurie activity required to deliver the therapeutic dose. A therapeutic dose of 75 cGy total-body dose (attenuated to 65 cGy in patients with platelet counts of 101,000 to 149,000 cells/mm(3)) was given 7 to 14 days after the dosimetric dose.Forty-five of 47 patients were treated with a single dosimetric and therapeutic dose. Twenty-seven patients (57%) had a response. The response rate was similar in patients with low-grade (57%) or transformed low-grade (60%) NHL. The median duration of response was 9.9 months. Fifteen patients (32%) achieved a complete response (CR; 10 CRs and five clinical CRs), including five patients (50%) with transformed low-grade NHL. The median duration of CR was 19.9 months, and six patients have an ongoing CR. Treatment was well tolerated, with the principal toxicity being hematologic. The most common nonhematologic toxicities that were considered to be possibly related to the treatment included mild to moderate fatigue (32%), nausea (30%), fever (26%), vomiting (15%), infection (13%), pruritus (13%), and rash (13%). Additionally, one patient developed human-antimouse antibodies.Iodine-131 tositumomab produced a high overall response rate, and approximately one third of patients had a CR despite having chemotherapy-relapsed or refractory low-grade or transformed low-grade NHL.
View details for Web of Science ID 000086020600021
View details for PubMedID 10715303
Phase II trial of yttrium-90-DOTA-biotin pretargeted by NR-LU-10 antibody/streptavidin in patients with metastatic colon cancer
CLINICAL CANCER RESEARCH
2000; 6 (2): 406-414
A Phase II study of yttrium-90-tetra-azacyclododecanetetra-acetic acid-biotin (90Y-DOTA-biotin) pretargeted by NR-LU-10 antibody/streptavidin (SA) was performed. The primary objectives of the study were to evaluate the efficacy and safety of this therapy in patients with metastatic colon cancer. Twenty-five patients were treated with a single dose of 110 mCi/m2 (mean administered dose, 106.5 +/- 10.3 mCi/m2) of 90Y-DOTA-biotin. There were three components of the therapy. Patients first received NR-LU-10/SA on day 1. A clearing agent (biotin-galactose-human serum albumin) was administered approximately 48 h after the NR-LU-10/SA to remove residual circulating unbound NR-LU-10/SA. Lastly, 24 h after administration of clearing agent, patients received biotin-DOTA-labeled with 110 mCi/m2 90Y. All three components of the therapy were administered i.v. Both hematological and nonhematological toxicities were observed. Diarrhea was the most frequent grade 4 nonhematological toxicity (16%; with 16% grade 3 diarrhea). Hematological toxicity was less severe with 8% grade 3 and 8% grade 4 neutropenia and 8% grade 3 and 16% grade 4 thrombocytopenia. The overall response rate was 8%. Two partial responders had freedom from progression of 16 weeks. Four patients (16%) had stable disease with freedom from progression of 10-20 weeks. Despite the relatively disappointing results of this study in terms of therapeutic efficacy and toxicity, proof of principle was obtained for the pretargeting approach. In addition, valuable new information was obtained about normal tissue tolerance to low-dose-rate irradiation that will help to provide useful guidelines for future study designs.
View details for Web of Science ID 000085502600013
View details for PubMedID 10690517
- Introduction Seminars in radiation oncology 2000; 10 (2): 71–72
Radiation absorbed dose estimation for Y-90-DOTA-biotin with pretargeted NR-LU-10/streptavidin
CANCER BIOTHERAPY AND RADIOPHARMACEUTICALS
1999; 14 (5): 381-395
Pretargeted radioimmunotherapy permits the administration of doses of 90Y five times higher than is possible with antibodies directly labeled with 90Yttrium (90Y). These high doses of 90Y introduced new issues for dosimetry that were not encountered in prior studies using conventional radioimmunotherapy. We have addressed these issues here and correlated dosimetry estimates with observed toxicity and tumor responses.The pretargeted radioimmunotherapy (PRIT) system employed the antibody NR-LU-10 conjugated with streptavidin, a glycoprotein clearing agent and 90Y-DOTA-biotin. A single dose of 90Y was escalated to 140 mCi/m2. Indium-111(111In) (3-5 mCi) DOTA-biotin was co-injected for gamma camera imaging and dosimetry assessment. The effect of bremsstrahlung radiation from increasing 90Y activity levels with a constant dose of 111In was studied using a phantom. Patient images identified the intestinal tract and the kidneys as potential organs at risk of clinically significant radiation toxicity. A method of measuring the activity localized in the intestinal tract was developed, and S values were calculated to estimate intestinal wall dose from radioactivity present in the intestine. Intestinal, bone marrow and renal toxicity were observed. Coefficients were derived for correlating the relationships between observed intestinal and marrow toxicity and the estimated radiation absorbed doses.At an 90Y:111In ratio of 50:1, bremsstrahlung radiation accounted for 12% of the counts in the images. Grade IV diarrhea was observed in patients estimated to have received 6850-14,000 cGy to the large intestinal wall. The correlation coefficient of intestinal toxicity with absorbed dose was 0.64. Myelotoxicity (measured as grade of suppression of absolute neutrophil count) correlated better with marrow dose (r = 0.72) than with the whole body dose, (r = 0.44). Delayed renal toxicity was observed in two patients 8 and 11 months following therapy. Tumor response was seen in the two patients with the highest estimated dose to tumor, 4,000-6,000 cGy.Dosimetry is feasible using 111In as a tracer in the presence of high 90Y activity. The absorbed dose estimates derived in the PRIT schema correlated moderately well with clinically observed toxicity and response.
View details for Web of Science ID 000083129300007
View details for PubMedID 10850323
G(2)/M-phase arrest and death by apoptosis of HL60 cells irradiated with exponentially decreasing low-dose-rate gamma radiation
1999; 151 (6): 659-669
Cells of the TP53-deficient human leukemia cell line HL60 continue to progress throughout the cell cycle and arrest in the G2/M phase during protracted exposure to exponentially decreasing low-dose-rate radiation. We have hypothesized that G2/M-phase arrest contributes to the extent of radiation-induced cell death by apoptosis as well as to overall cell killing. To test this hypothesis, we used caffeine and nocodazole to alter the duration of G2/M-phase arrest of HL60 cells exposed to exponentially decreasing low-dose-rate irradiation and measured the activity of G2/M-phase checkpoint proteins, redistribution of cells in the phases of the cell cycle, cell death by apoptosis, and overall survival after irradiation. The results from these experiments demonstrate that concomitant exposure of HL60 cells to caffeine (2 mM) during irradiation inhibited radiation-induced tyrosine 15 phosphorylation of the G2/M-phase transition checkpoint protein CDC2/p34 kinase and reduced G2/M-phase arrest by 40-46% compared to cells irradiated without caffeine. Radiation-induced apoptosis also decreased by 36-50% in cells treated with caffeine and radiation compared to cells treated with radiation alone. Radiation survival was significantly increased by exposure to caffeine. In contrast, prolongation of G2/M-phase arrest by pre-incubation with nocodazole enhanced radiation-induced apoptosis and overall radiation-induced cell killing. To further study the role of cell death by apoptosis in the response to exponentially decreasing low-dose-rate irradiation, HL60 cells were transfected with the BCL2 proto-oncogene. The extent of G2/M-phase arrest was similar for parental, neomycin-transfected control and BCL2-transfected cells during and after exponentially decreasing low-dose-rate irradiation. However, there were significant differences (P < 0.01) in the extent of radiation-induced apoptosis of parental and neomycin- and BCL2-transfected cells after irradiation, with significantly less radiation-induced apoptosis and higher overall survival in BCL2-transfected cells than similarly irradiated control cells. These data demonstrate that radiation-induced G2/M-phase arrest and subsequent induction of apoptosis play an important role in the response of HL60 cells to low-dose-rate irradiation and suggest that it may be possible to increase radiation-induced apoptosis by altering the extent of G2/M-phase arrest. These findings are clinically relevant and suggest a novel therapeutic strategy for increasing the efficacy of brachytherapy and radioimmunotherapy.
View details for Web of Science ID 000080602300004
View details for PubMedID 10360785
The role of radiation-induced apoptosis as a determinant of tumor responses to radiation therapy
1999; 4 (2): 115-143
Ionizing radiation is an effective means of killing tumor cells. Approximately 50% of all American cancer patients are treated with radiotherapy at some time during the course of their disease, making radiation one of the most widely used cytotoxic therapies. Currently, much effort is focused on understanding the molecular pathways that regulate tumor cell survival following radiotherapy, with the long term goal of developing novel therapeutic strategies for specifically sensitizing tumors to radiation. At present, there is particular interest in the role of tumor cell apoptotic potential as a regulator of both intrinsic and extrinsic determinants of the response of tumors to radiation therapy. Here we review what is currently known about the role of apoptosis as a mechanism of tumor cell killing by ionizing radiation and the relative contribution of apoptosis to cellular radiosensitivity and the ability to control human cancers using radiotherapy. The following topics will be discussed: (1) radiation-induced apoptosis in normal and malignant cells, (2) clinical findings with respect to apoptosis in human cancers treated with radiotherapy, (3) the contribution of apoptosis to intrinsic radiosensitivity in vitro, (4) the relevance of apoptosis to treatment outcome in experimental tumor models in vivo and (5) the potential of exploiting apoptosis as a means to improve the therapeutic efficacy of radiotherapy.
View details for Web of Science ID 000081408800006
View details for PubMedID 14634289
Radiosensitization by intratumoral administration of cisplatin in a sustained-release drug delivery system
RADIOTHERAPY AND ONCOLOGY
1999; 50 (2): 215-223
Effects of combining local irradiation and intratumoral (i.t.) administration of cisplatin (CDDP) in a sustained-release drug delivery system (epi gel) were studied in a murine SCCVII squamous cell carcinoma model in mice.The epinephrine injectable gel was used as a drug delivery system. Intratumoral pharmacokinetics of CDDP was studied by using 195mPt-CDDP. The tumor volume quadrupling time (TVQT) and tumor growth delay (TGD) time were used to evaluate the antitumor efficacy of treatment regimens.The concentration and residence of 195mPt-CDDP was significantly higher in tumors treated with 195mpt-CDDP/epi gel than in tumors treated with 195mPt CDDP gel or 195mPt-CDDP suspension. Intratumoral administration of CDDP/epi gel (4 mg/kg) produced an average TGD time of 15.5 +/- 2.8 days, which was 5.2 - 7.4 times longer than CDDP suspension i.t. or i.p. When combined with a single dose of radiation (10 Gy), i.t. administration of CDDP/epi gel was 2.0 - 3.6-fold as effective as administered i.t. in suspension (39.2 +/- 4.1 vs. 19.8 +/- 3.9 days of TGD, P < 0.05) or i.p. in solution (39.2 +/- 4.1 vs. 11.0 +/- 1.6 days, P < 0.001) in inhibiting tumor growth and produced 20-60% complete remission of tumors. When combined with fractionated irradiation, pre-irradiation CDDP administration was more effective than post-radiation administration (26.7 vs. 12.1 days of TGD, P < 0.05). Mice treated with CDDP/epi gel i.t. alone or in combination with irradiation, had little systemic toxicity.Intratumoral administration of CDDP using the sustained-release drug delivery system is an efficient and safe method to maximize the drug concentration in tumor, minimize the systemic toxicity and enhance antitumor efficacy of irradiation.
View details for Web of Science ID 000079523900012
View details for PubMedID 10368046
Myc activation reduces fibroblast clonogenicity via an apoptotic mechanism that can be suppressed by a soluble paracrine factor
1998; 127 (1-2): 211-219
The c-Myc transcription factor is involved in the regulation of cellular proliferation and differentiation and is one of the most frequently deregulated genes in human cancers. While c-Myc is known to enhance the proliferative potential of cells, its activation in immortalized fibroblasts has been found to result in apoptosis following gamma-irradiation or under adverse growth conditions, including serum deprivation and hypoxia. When plating Rat-1 fibroblasts at low cell densities (100 cells/100 mm plate), we observed a substantial reduction in the clonogenicity of cells with deregulated c-Myc activity compared to cells with normal c-Myc activity. This difference in clonogenicity was apparent despite the fact that cells were plated in media containing sufficient serum and oxygen concentrations known to suppress apoptosis of exponentially growing Rat-1 fibroblasts with activated c-Myc. Therefore, we hypothesized that the observed reduction in plating efficiency in cells with activated c-Myc occurred via an apoptotic mechanism and that a fibroblast-derived factor was required for suppression of apoptosis. Overexpression of the anti-apoptotic oncogene, Bcl-2, in cells with activated c-Myc restored the plating efficiency to normal levels in cells plated at low cell densities. This strongly suggested that the decreased clonogenicity of fibroblasts with altered c-Myc activity resulted from enhanced apoptosis of the cells under these conditions. Furthermore, plating cells on a feeder layer of lethally-irradiated fibroblasts or in Rat-1 conditioned media increased the plating efficiencies of sparsely plated cells in a dose-dependent fashion. These results suggest that in addition to previously reported requirements for serum-derived growth factors and normal oxygen conditions, a paracrine factor liberated by Rat-1 fibroblasts is required to suppress c-Myc-induced apoptosis in these cells.
View details for Web of Science ID 000073597200029
View details for PubMedID 9619879
Direct evidence that apoptosis enhances tumor responses to fractionated radiotherapy
1998; 58 (9): 1779-1784
Currently, the contribution of cellular apoptotic sensitivity to tumor response after radiation therapy remains controversial. To address this issue, the survival of Rat-1 fibroblasts containing a 4-hydroxytamoxifen-regulated c-Myc allele, c-MycER (T. D. Littlewood et al., Nucleic Acids Res., 23: 1686-1690, 1995), after single and fractionated doses of radiation was investigated. This model system allows pharmacological regulation of apoptosis sensitivity in the same cells in vitro and as xenograft tumors derived from these cells in vivo (G. I. Evan et al., Cell, 69: 119-128, 1992; R. M. Alarcon et al., Cancer Res., 56: 4315-4319, 1996). Activating c-MycER in vitro resulted in marked sensitization of Rat-1 fibroblasts to the effects of both single-dose and fractionated irradiation as measured by the induction of apoptosis and clonogenic survival. Overexpression of the antiapoptosis protein Bcl-2 suppressed the induction of apoptosis and increased clonogenic survival in cells with activated c-Myc after single-dose and fractionated radiation. Systemic time-release implant delivery of 4-hydroxytamoxifen to severe combined immunodeficient mice bearing Rat-1-MycER tumors over the course of either single-dose (10 Gy) or fractionated (five fractions of 2 Gy) radiotherapy resulted in prolonged tumor growth delay relative to identical tumors from mice that received placebo implants. Furthermore, tumors derived from Rat-1-MycER cells that overexpressed Bcl-2 exhibited shorter tumor growth delays relative to similarly treated Rat-1-MycER tumors. The length of tumor growth delay after single-dose or fractionated radiotherapy strongly correlated with the extent of radiation-induced apoptosis in the xenograft tumors as measured by terminal deoxynucleotidyl transferase-mediated nick end labeling. These in vivo results provide direct evidence that increasing the sensitivity of tumor cells to die by apoptosis increases the efficacy of fractionated radiotherapy by reducing tumor cell clonogenic survival.
View details for Web of Science ID 000073344700003
View details for PubMedID 9581811
Pretargeted Radioimmunotherapy (TM) with antibody-streptavidin and Y-90 DOTA-Biotin (Avicidin (R)): Result of a dose escalation study.
SOC NUCLEAR MEDICINE INC. 1998: 71P–71P
View details for Web of Science ID 000073560300272
p53 mediates apoptosis induced by c-Myc activation in hypoxic or gamma irradiated fibroblasts
CELL DEATH AND DIFFERENTIATION
1998; 5 (2): 141-147
Deregulated c-Myc expression leads to a cellular state where proliferation and apoptosis are equally favored depending on the cellular microenvironment. Since the apoptotic sensitivity of many cells is influenced by the status of the p53 tumor suppressor gene, we investigated whether the induction of apoptosis by DNA damage or non-genotoxic stress are also influenced by the p53 status of cells with altered c-Myc activity. Rat-1 fibroblasts expressing a conditional c-Myc allele (c-MycER), were transfected to express an antisense RNA complimentary to p53 mRNA. Expression of antisense p53 RNA decreased p53 protein levels and delayed p53 accumulation following c-Myc activation. Under hypoxic or low serum conditions, cells expressing antisense p53 were substantially more resistant to c-Myc-induced apoptosis than were control cells. c-Myc activation also sensitized Rat-1 cells to radiation-induced apoptosis. Rat-1 cells expressing antisense p53 RNA were more resistant to apoptosis induced by the combined effects of c-Myc activation and gamma irradiation. In a similar manner, apoptosis induced by c-Myc in serum starved, hypoxic or gamma irradiated fibroblasts was also inhibited by Bcl-2. These data indicate that p53 is involved in c-Myc-mediated apoptosis under a variety of stresses which may influence tumor growth, evolution and response to therapy.
View details for Web of Science ID 000071647200003
View details for PubMedID 10200458
Effects of keratinocyte growth factor on the proliferation and radiation survival of human squamous cell carcinoma cell lines in vitro and in vivo
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
1998; 40 (1): 177-187
Keratinocyte growth factor (KGF) has potent mitogenic activity on normal epithelial cells and has been found to enhance intestinal crypt cell survival in irradiated mice and to prevent radiation and chemotherapy-induced mucositis in animal models. The purpose of the study reported here is to investigate the effect of recombinant human KGF on the proliferation and survival of human squamous carcinoma cell lines following irradiation.The level of KGF receptor (KGFR) mRNA in normal Balb/Mk cell line and human head and neck squamous carcinoma cell lines was assessed using a RNase protection assay. The clonogenic assay and MTT assay were used to study the proliferative effects of KGF on human tumor cell lines and Balb/MK cell line in vitro. Effects of KGF on in vivo tumor growth and radiosensitivity were studied in three KGFR-positive human squamous cell carcinoma xenografts (FaDu, Detroit 562 and A431) in nude mice, and a murine KGFR-negative melanoma tumor (B16) in Balb/c mice.Seven of 10 tumor cell lines studied expressed KGFR mRNA. None of these tumor cell lines showed enhanced proliferation when exposed to KGF for 2 days or less. Prolonged exposure to KGF for 7 days or longer resulted in low level stimulation of proliferation in both clonogenic and MTT assays in four of seven KGFR-positive cell lines. Two KGFR-negative cell lines also had a low proliferative response to KGF in a clonogenic assay, but not in the MTT assay. Normal keratinocyte Balb/MK cells, which expressed a moderate level of KGFR mRNA, had a strongly proliferative response to KGF. Its KGF enhancement ratio (KER) of plating efficiency was 24-70 times higher than that of the tumor cells studied (p < 0.001). The KGF-stimulated tumor cell growth was almost completely inhibited by heparin or epidermal growth factor (EGF). There were no significant differences (p > 0.05) in the survival of any of tumor cell lines in the presence or absence of KGF (100 ng/ml) irradiated with doses of 0-15 Gy, and no significant differences (p > 0.05) between the radiobiological parameters D0, Dq, and n number from the SHMT model, alpha, beta, and alpha/beta ratio from the LQ model and SF2 for radiation survival curves for cell lines irradiated in the presence or absence of KGF. Three KGFR-positive human squamous cell carcinoma xenografts in nude mice, and a murine KGFR-negative melanoma tumor in Balb/c mice treated with 1.0 mg/kg of KGF for 3 days grew at the same rate as in untreated mice.The recombinant human KGF resulted in little or no stimulation of the proliferation of human head and neck squamous tumor cell lines and did not affect the radiosensitivity of these cell lines in vitro and in vivo. Therefore, KGF may be of clinical value in preventing radiation-induced mucositis and may have the potential to increase the therapeutic index of radiotherapy for treatment of cancers.
View details for Web of Science ID 000071164200027
View details for PubMedID 9422575
Radiobiologic studies of radioimmunotherapy and external beam radiotherapy in vitro and in vivo in human renal cell carcinoma xenografts
6th Conference on Radioimmunodetection and Radioimmunotherapy of Cancer
WILEY-BLACKWELL. 1997: 2519–28
Previous studies suggest that the radiobiologic characteristics of in vitro survival curves are important determinants of the response of tumors to both conventional radiotherapy and radioimmunotherapy (RIT). The purpose of this study was to elucidate the relationship between in vitro radiation survival curve parameters and the relative sensitivity of tumor to RIT, exponentially decreasing low dose rate (ED LDR) irradiation and conventional high dose rate (HDR) fractionated external beam radiotherapy.Two human renal cell carcinoma cell lines, Caki-1 and A498, were used in vitro and nude mouse xenograft studies. HDR external beam gamma irradiation (dose rate, 430 centigray [cGy]/minute) and ED LDR irradiation (initial dose rate, 22-25 cGy/hour) were performed with a cesium-137 (137Cs) gamma irradiator. RIT was carried out with yttrium-90 (90Y-labeled monoclonal antibody NR-LU-10, and the absorbed radiation doses were calculated by medical internal radiation dose methodology. A clonogenic assay was used to generate radiation survival curves, and a computer FIT program was used to calculate the radiobiologic parameters. The antitumor efficacy of the different treatments was compared in vivo using a tumor regrowth delay assay in these two tumor xenograft models.The radiation survival curves showed that the Caki-1 cell line was more sensitive to both HDR and ED LDR irradiation than A498 in vitro. The Caki-1 cell line, compared with A498, had a larger alpha (0.39 vs. 0.15 Gy following HDR and 0.32 vs. 0.21 Gy following ED LDR) and alpha-to-beta ratio (6.92 vs. 2.60 Gy for HDR and 40.0 vs. 19.2 Gy for ED LDR), a smaller n number (5.13 vs. 23 for HDR and 1.16 vs. 3.53 for ED LDR), a lower quasi-threshold dose (Dq) (1.60 vs. 3.15 Gy for HDR and 0.35 vs. 1.76 Gy for ED LDR), and a lower surviving fraction at 2 Gy (SF2) (0.37 vs. 0.60 for HDR and 0.51 vs. 0.61 for ED LDR), suggesting that Caki-1, compared with A498, had a steep initial slope and a small shoulder. The final slope represented by the beta value and D0 dose (the dose (Gy) required to reduce the fraction of surviving cells of 37% of its previous value in the exponential region of the survival curves) did not vary significantly between these two cell lines at either HDR or ED LDR irradiation. Tumor volume doubling times were 4.0 +/- 1.5 days for Caki-1 and 4.2 +/- 1.8 days for A498 tumor xenografts. One hundred microCi/50 microg of 90Y-labeled, isotype-matched irrelevant monoclonal antibody CCOO16-3 produced a tumor growth delay time (TGD) of 2.1 days in Caki-1 tumors but had no effect on A498 tumors (P < 0.05). RIT with 100 microCi of 90Y-NR-LU-10 resulted in a TGD of 4.8 days for Caki-1 tumors, whereas 100 microCi and 150 microCi of 90Y-NR-LU-10 produced a TGD of 1.9 and 2.7 days for A498 tumors, respectively. Estimated absorbed doses were 21.9 Gy in Caki-1 tumors treated with 100 microCi of 90Y-NR-LU-10 and 14.5 Gy and 21.8 Gy in A498 tumors treated with 100 microCi and 150 microCi of 90Y-NR-LU-10, respectively. The weighted normal tissue absorbed doses were 7.4 Gy for Caki-1 tumor-bearing mice and 9.0 Gy for A498 tumor-bearing mice (P > 0.05). To compare the responses of Caki-1 and A498 xenografts to RIT with external beam ED LDR and HDR irradiation, tumor-bearing mice were treated with equivalent doses (20-22 Gy) of 1) RIT with 90Y-NR-LU-10 (100 microCi for Caki-1 and 150 microCi for A498), 2) continuous ED LDR 137Cs irradiation with a initial dose rate of 22 cGy/hour, or 3) HDR X-irradiation (2 Gy x 10 fractions in 2 weeks). The TGDs produced by RIT, ED LDR, and HDR were 5.3, 9.7, and 8.3 days for Caki-1 and 2.7, 5.1, and 5.8 days for A498. The relative efficacy of RIT in these xenograft models correlated well with the radiobiologic parameters (i.e., the size of the initial slope and shoulder) of in vitro survival curves following HDR and ED LDR irradiation in these cell lines. (ABSTRACT TRUNCATED)
View details for Web of Science ID 000071035600026
View details for PubMedID 9406705
- A prospective study of radiation therapy-associated thrombocytopenia BLOOD 1997; 90 (10): 4237-4238
Enhancement of murine intestinal stem cell survival after irradiation by keratinocyte growth factor
1997; 148 (3): 248-253
Radiation-induced gastrointestinal toxicity is due in part to the killing of the clonogenic crypt cells and eventual depopulation of the villi. Keratinocyte growth factor (KGF), a member of the fibroblast growth factor family (FGF-7), has been shown to stimulate proliferation of cells along the murine digestive tract from the foregut to the colon. Using an in vivo microcolony assay, we found that 1.0 mg/kg KGF administered intravenously (i.v.) for 3 consecutive days (2 days before, 1 day before and 2 h after irradiation) increased the number of surviving crypts by a factor of 2.6, 2.7 and 2.4 in the duodenum, jejunum and ileum, respectively, after a single-dose whole-body irradiation (10-16 Gy) (P < 0.001). Treatment of mice with KGF i.v. significantly increased the D0 of the radiation survival curves by 0.37, 0.22 and 0.36 Gy, leading to dose modification factors of 1.28, 1.16 and 1.24 for duodenal, jejunal and ileal crypt cells, respectively. Similar results were obtained with KGF administered subcutaneously. Treatment with both KGF and stem cell factor (previously shown to enhance intestinal crypt survival after total-body irradiation) increased the number of surviving crypt cells after irradiation to levels similar to that in animals treated with KGF alone. Administration of KGF for 7 consecutive days (beginning 2 days prior to irradiation) increased the LD(50/10) from 5.50 Gy/day to 5.90 Gy/day (P = 0.05) for animals irradiated with five daily fractions to a local abdominal field. These results suggest that KGF may be of clinical value in reducing radiation toxicity to the intestine.
View details for Web of Science ID A1997XU08700007
View details for PubMedID 9291356
Influence of Bcl-2 overexpression on Na+/K+-ATPase pump activity: Correlation with radiation-induced programmed cell death
JOURNAL OF CELLULAR PHYSIOLOGY
1997; 171 (3): 299-304
Bcl-2 overexpression in transfected PW cells is associated with inhibition of radiation-induced programmed cell death (PCD). We have previously reported that there is a relationship between inhibition of radiation-induced PCD and membrane hyperpolarization in these cells. In this article, we report that Na+/ K(+)-ATPase pump activity, as measured by the uptake of Rubidium-86 (86Rb+), is significantly higher in Bcl-2 overexpressing PW cells than in control PW cells, and that pump activity following irradiation with doses > or = 500 cGy was reduced to a lesser extent in the Bcl-2 transfectants than in the control cells. When PW-Bcl-2 cells were incubated with a dose of ouabain (1 microM) that decreased pump activity significantly, but did not induce PCD, the previously reported protection from radiation-induced PCD associated with overexpression of Bcl-2 no longer existed. In order to demonstrate that reactive oxygen species (ROS) affected Na+/ K(+)-ATPase pump activity, cells were incubated with N-acetyl cysteine (NAC) prior to irradiation, or treated with the ROS generating drug buthionine sulphoxamine (BSO). 86Rb+ uptake was significantly higher in irradiated cells incubated with NAC compared to cells irradiated in the absence of NAC, while BSO resulted in lower levels of 86Rb+ uptake, suggesting that the effects of radiation on the Na+/K(+)-ATPase pump were due to ROS. Furthermore, the resting cell membrane potential of cells exposed to NAC were slightly hyperpolarized compared to control PW cells, whereas cells exposed to BSO were depolarized in comparison to control PW cells. In summary, this data suggests that Bcl-2 affects Na+/K(+)-ATPase pump activity, which is associated with the resting membrane potential and the level of susceptibility to radiation-induced PCD.
View details for Web of Science ID A1997XL16600008
View details for PubMedID 9180899
Radiotherapy-associated neutropenia and thrombocytopenia: Analysis of risk factors and development of a predictive model
1997; 89 (7): 2303-2310
Risk factors for unscheduled interruptions in radiotherapy courses completed between June 1989 and August 1995, lasting > or = 2 days, and associated with World Health Organization grade III-IV neutropenia or thrombocytopenia were studied retrospectively. A group of controls was randomly selected. Potential risk factors for myelosuppression were analyzed using univariate and multivariate analyses. The most important risk factors for treatment interruption with thrombocytopenia were concurrent chemotherapy (odds ratio [OR], 45.5; P < .001), increasing percentage of marrow irradiated (OR, 4.1 for each 20%; P < .001), and brain metastases (OR, 7.3; P = .01). Other significant (P < .05) factors were leukemia/lymphoma, bone or bone marrow metastases, and prior chemotherapy. The most important risk factors for treatment interruptions with neutropenia were concurrent chemotherapy (OR, 42.1; P < .001) and increasing percentage of marrow irradiated (OR, 3.3 for each 20%; P < .001). Similarly, the most important risk factors for treatment interruptions with both thrombocytopenia and neutropenia were concurrent chemotherapy (OR, 48.6; P < .001) and increasing percentage of marrow irradiated (OR, 3.9 for each 20%; P < .001). Other significant (P < .05) factors in these groups were bone marrow or brain metastases and previous chemotherapy. These data were used to create a model, assigning patients to groups at high, intermediate, or low risk for treatment interruption with thrombocytopenia. High-risk patients may be candidates for clinical trials of a platelet growth factor.
View details for Web of Science ID A1997WQ35900008
View details for PubMedID 9116273
Modulation of c-myc activity and apoptosis in vivo
1996; 56 (19): 4315-4319
We have developed an animal tumor model system to study the effects of c-Myc activation on apoptosis induction in vivo. Tumors were generated in SCID mice from Rat-1 fibroblasts that constitutively express an inactive c-Myc-estrogen receptor fusion protein (T.D. Littlewood et al, Nucleic Acids Res., 23: 1686 -1690, 1995), which is activated in vivo by the administration of 4-hydroxytamoxifen in time release pellets. We demonstrate that activation of c-Myc results in a substantial increase in the number of apoptotic tumor cells and that this apoptosis is predominant in regions of tumor hypoxia. c-Myc-induced apoptosis of hypoxic cells is inhibited in tumors that overexpress the human Bcl-2 protein. Bcl-2, however, does not prevent p53 protein accumulation or the down-regulation of the cyclin-cdk inhibitor p27 protein following c-Myc activation by 4-hydroxytamoxifen. This result suggests that Bcl-2 does not affect c-Myc function directly but acts downstream of c-Myc to inhibit apoptosis. We propose that the ability of activated c-Myc to enhance cellular proliferation might contribute to the genesis of early neoplasms that are held in check by the alternate ability of c-Myc to induce apoptosis of cells that have outgrown their supply of oxygen or other factors associated with hypoxic regions of solid tumors. Secondary genetic lesions downstream of c-Myc that suppress the apoptotic potential of tumor cells, such as Bcl-2 overexpression, might play an important role in the malignant progression of these tumors because they would disrupt the balance between apoptosis and proliferation initiated by c-Myc deregulation.
View details for Web of Science ID A1996VK30700006
View details for PubMedID 8813114
Treatment of hormone-refractory prostate cancer with Y-90-CYT-356 monoclonal antibody
CLINICAL CANCER RESEARCH
1996; 2 (8): 1289-1297
A Phase I dose-escalation study using 90Y-CYT-356 monoclonal antibody was performed in 12 patients with hormone-refractory prostate carcinoma. Biodistribution studies using 111In-CYT-356 were performed 1 week before 90Y-CYT-356 administration. Of the 12 patients, 58% had at least one site of disease imaged after administration of 111In-CYT-356. The dose of 90Y ranged from 1.83-12 mCi/m2. Both 111In and 90Y-CYT-356 were tolerated well, without significant nonhematological toxicity. Myelosuppression was the dose-limiting toxicity and occurred at dose levels of 4.5-12 mCi/m2. Of the patients receiving =9 mCi/m2, 55% had grade 1 or 2 leukopenia and/or thrombocytopenia. Two of three patients treated with 12 mCi/m2 experienced grade 3 thrombocytopenia and leukopenia. One patient treated with 12 mCi/m2 had grade 4 neutropenia. The maximum tolerated dose of 90Y-CYT-356 was 9 mCi/m2. Only one patient developed a human anti-mouse antibody 4 weeks after treatment. No patient attained a complete or partial response based on prostate-specific antigen and/or radiological criteria. Three patients had transient subjective improvement in the symptomatology of their disease. In addition, patients treated with 12 mCi/m2 of 90Y-CYT-356 had a slightly longer freedom from disease progression than patients treated with doses of 90Y-CYT-356 =9 mCi/m2.
View details for Web of Science ID A1996VB19900006
View details for PubMedID 9816299
Association of BCL-2 with membrane hyperpolarization and radioresistance
JOURNAL OF CELLULAR PHYSIOLOGY
1996; 168 (1): 114-122
The resting membrane potential of parental, neomycin control, and Bcl-2 transfected cells was measured, and the effect of membrane hyperpolarization or depolarization on radiosensitivity was studied. Bcl-2 transfected cells were significantly more radioresistant than control cells and were significantly hyperpolarized compared to parental and neomycin control transfected PW and HL60 cells. Hyperpolarization of the parental and neomycin control transfected cells by valinomycin significantly increased the radioresistance of these cells to such an extent that there was no longer a significant difference in the survival of the valinomycin treated and irradiated control cells compared to similarly irradiated Bcl-2 transfected cells. In contrast, depolarization of the Bcl-2 transfected PW and HL60 cells decreased the radioresistance of the Bcl-2 transfectants to a level similar to that of the control cells. The data presented here suggest that overexpression of Bcl-2 affects membrane potential and that this hyperpolarization is associated with increased radioresistance of cells that overexpress Bcl-2. Furthermore, Bcl-2 transfected cells were also less susceptible to the specific Na+/K(+)-ATPase inhibitor ouabain, suggesting that Bcl-2 may act at the level of the Na+/K(+)-ATPase pump.
View details for Web of Science ID A1996UR69400014
View details for PubMedID 8647905
Intratumoral radioimmunotherapy of a human colon cancer xenograft using a sustained-release gel
RADIOTHERAPY AND ONCOLOGY
1996; 39 (2): 179-189
Low tumor uptake and normal tissue toxicity limit the efficacy of RIT for the treatment of solid tumors. In this study, an intratumoral injectable gel drug delivery system for local administration of RIT was evaluated using the LS174T human colon cancer xenograft model in SCID mice. The injectable gel is a collagen-based drug delivery system designed for intratumoral (i.t.) administration, which has previously been shown to enhance drug retention at the injection site and reduce systemic drug exposure. We compared the local (tumor) retention and biodistribution of 111In-labeled NR-LU-10 monoclonal antibody given i.t. in the injectable gel versus simple aqueous solution. 111In gel given i.t. and 111In-NR-LU-10 given intraperitoneally (i.p.) were used as controls. The results showed that tumors treated with 111In-NR-LU-10 gel maintained the highest levels of radioactivity for up to 96 h. At 48 h after the administration of 111In-NR-LU-10 gel i.t., 111In-NR-LU-10 solution i.t., 111In gel i.t., or 111In-NR-LU-10 i.p., the level of radioactivity remaining in each gram of tumor was 98, 49, 45, and 16% of the injected dose, respectively. It was estimated that if 100 microCi of 90Y-NR-LU-10 were administered similarly, tumor treated with 90Y-NR-LU-10 gel i.t. would receive a dose of 90.0 Gy, whereas normal tissues in the same animal would receive a dose of approximately 2.43 Gy. In contrast, if 90Y-NR-LU-10 were delivered i.p., a comparable tumor would receive a dose of 16.8 Gy and corresponding normal tissues would receive 3.36 Gy. Consistent with these estimates, enhanced antitumor efficacy was observed when 90Y-NR-LU-10 gel was administered i.t. Tumor growth delay time was 6.9-fold (P < 0.01) longer in these animals (14.4 days) than in animals treated with 90Y-NR-LU-10 i.p. (2.1 days). Systemic toxicity was also significantly reduced in gel-treated animals as monitored by loss of body weight. This study demonstrated that intratumoral delivery of 90Y-NR-LU-10 gel markedly increased the retention of the radioisotope in tumors, enhanced the antitumor efficacy, and reduced systemic toxicity compared to systemic administration of the radiolabeled antibody. This injectable gel drug delivery system may allow for improvement in the therapeutic index for RIT.
View details for Web of Science ID A1996UM70100011
View details for PubMedID 8735485
Over-expression of Bcl-2 protects against apoptosis induced by the bioreductive cytotoxic drug SR4233 (tirapazamine)
CELL DEATH AND DIFFERENTIATION
1996; 3 (2): 215-222
The human B-cell lymphoma cell line PW undergoes radiation-induced programmed cell death (PCD). Bcl-2 transfected PW cells, that overexpressed Bcl-2, were significantly more radioresistant than parental or neomycin control transfected PW cells. The viability of Bcl-2 transfected cells was significantly greater than that of parental PW cells treated with the bioreductive cytotoxin SR4233 under aerobic conditions. Bcl-2 transfectants were also significantly more resistant to hypoxia-induced PCD. However, there was no significant difference in the viability of parental and Bcl-2 transfected cells exposed to SR4233 under hypoxic conditions (pO(2)<100 ppm). Incubation of parental PW cells with N-acetyl cysteine decreased the cytotoxicity of SR4233 under aerobic but not anaerobic conditions. Depletion of cellular glutathione with buthionine sulphoxamine killed nearly 100% of control PW cells, but none of the Bcl-2 transfectants under the same conditions. The TBARS assay for lipid peroxidation showed that Bcl-2 transfectants had a significantly lower level of lipid peroxidation than parental PW cells following a 24 hour constant exposure to SR4233 under aerobic conditions. These results suggest that Bcl-2 overexpression inhibits PCD induced by the bioreductive cytotoxin SR4233 under aerobic conditions as well as PCD induced by hypoxia, and that there are other pathways leading to PCD that are unaffected by Bcl-2 overexpression.
View details for Web of Science ID A1996UT34700009
View details for PubMedID 17180085
Yttrium-90-labeled anti-CD20 monoclonal antibody therapy of recurrent B-cell lymphoma
CLINICAL CANCER RESEARCH
1996; 2 (3): 457-470
A Phase I/II dose escalation study of 90Y-murine anti-CD20 monoclonal antibody (mAb) in patients with recurrent B-cell lymphoma was performed. The primary objectives of the study were: (a) to determine the effect of the preinfusion of unlabeled anti-CD20 mAb on the biodistribution of 111In-anti-CD20 mAb; (b) to determine the maximal tolerated dose of 90Y-anti-CD20 mAb that does not require bone marrow transplantation; and (c) to evaluate the safety and antitumor effect of 90Y-anti-CD20 mAb in patients with recurrent B-cell lymphoma. Eighteen patients with relapsed low- or intermediate-grade non-Hodgkin's lymphoma were treated. Biodistribution studies with 111In-anti-CD20 mAb were performed prior to therapy. Groups of three or four patients were treated at dose levels of approximately 13.5, 20, 30, 40, and 50 mCi 90Y-anti-CD20 mAb. Three patients were retreated at the 40-mCi dose level. The use of unlabeled antibody affected the biodistribution favorably. Nonhematological toxicity was minimal. The only significant toxicity was myelosuppression. The overall response rate following a single dose of 90Y-anti-CD20 mAb therapy was 72%, with six complete responses and seven partial responses and freedom from progression of 3-29+ months following treatment. Radioimmunotherapy with =50 mCi 90Y-anti-CD20 mAb resulted in minimal nonhematological toxicity and durable clinical responses in patients with recurrent B-cell lymphoma. Doses of =40 mCi 90Y-anti-CD20 mAb were not myeloablative.
View details for Web of Science ID A1996TY62000004
View details for PubMedID 9816191
Treatment of cutaneous T-Cell lymphoma with chimeric anti-CD4 monoclonal antibody
1996; 87 (3): 893-899
Chimeric anti-CD4 monoclonal antibody was administered intravenously as a single dose to eight patients with mycosis fungoides. The dose was escalated throughout the study between patients groups, and individual patients received 50, 100, or 200 mg per dose. Seven of eight patients responded to treatment with an average freedom from progression of 25 weeks (range, 6 to 52 weeks). The treatment was well tolerated, and there was no clinical evidence of immunosuppression. Following treatment, there was significant suppression of peripheral blood CD4 counts in all patients for 1 to 22+ weeks. Only one patient made a very low titer human antichimeric antibody response. All but two patients made primary antibody and T-cell proliferative responses to a foreign antigen administered 24 hours after antibody infusion. However, there was generally marked, but temporary suppression of T-cell proliferative responses in vitro to phytohemagglutinin (PHA), tetanus toxoid, and normal donor lymphocytes. We conclude that at the dose levels studied, this antibody (1) had clinical efficacy against mycosis fungoides; (2) was well tolerated; (3) had a low level of immunogenicity; (4) decreased T-cell proliferative responses in vitro, and (5) did not induce tolerance to a foreign antigen.
View details for Web of Science ID A1996TT48400008
View details for PubMedID 8562959
Overview of studies on experimental radioimmunotherapy.
1995; 55 (23): 5832s-5836s
Experimental radioimmunotherapy (RIT) has significantly contributed to the development of clinical RIT. In this overview, the current status of experimental RIT is reviewed, including general principles of RIT and determinants of RIT effects. Areas of active research are reviewed, and the usefulness of multicell spheroids is compared to animal models. The radiobiology of RIT is discussed, and studies that have compared the relative efficacy of RIT with external beam radiation therapy are summarized. Approaches for increasing the therapeutic index of RIT are reviewed, including improvements in antibodies, labeling/chelation chemistry, selection of radionuclides, delivery, fractionated therapy, clearance of unbound radiolabeled monoclonal antibodies, protection of normal tissues, radiosensitization of tumors, utilization of colony-stimulating factors and bone marrow transplantation, and the use of novel targets for RIT and topoisomerase I inhibitors. RIT is a promising new therapy for a wide variety of malignancies that can best be optimized by continued research in the field of experimental RIT. Important areas of future research are discussed that may ultimately potentiate the efficacy and decrease the toxicity of RIT and help determine how to optimally combine RIT with other therapeutic modalities.
View details for PubMedID 7493355
(90)Yttrium labeled anti-CD20 therapy for recurrent B cell lymphoma
AMER SOC HEMATOLOGY. 1995: 1080–80
View details for Web of Science ID A1995TH91001082
EFFECTS OF STEM-CELL FACTOR ON THE GROWTH AND RADIATION SURVIVAL OF TUMOR-CELLS
1995; 55 (15): 3431-3437
Recombinant human stem cell factor (SCF) binds to the c-kit receptor on human bone marrow progenitor cells and enhances their survival following irradiation. Since the c-kit receptor has also been detected on malignant cells, experiments were performed to study the effect of SCF on the proliferation and radiation survival of a variety of both c-kit-positive and -negative human tumor cell lines using [3H]thymidine incorporation and colony formation assays. The addition of SCF to both c-kit-positive and -negative cell line cultures had no significant effect on the stimulation index (in [3H]thymidine assay). In contrast, colony formation by H69 (small cell lung cancer cell line), H128 (small cell lung cancer cell line), and HEL (erythroid leukemia cell line) cells was enhanced by SCF in a dose-dependent manner, but SCF did not promote the in vivo growth of H128 xenograft tumors in terms of graft rate, time from implantation to tumor detection, or tumor size. Furthermore, SCF did not significantly increase the surviving fraction of either c-kit-positive or -negative cell lines following radiation, and there were no statistically significant differences between D0 [defined by the slope of the terminal exponential region of the two-component (single-hit multitarget model) survival curve where slope = 1/D0], Dq (quasithreshold dose), n (extrapolation number), alpha, and beta values for any of the cell lines studied that were irradiated with and without SCF. Finally, nude mice with transplanted human LG425 cutaneous T-cell lymphoma (c-kit positive) were treated with 10 Gy with or without SCF (100 micrograms/kg i.p. 20 h before, 2 h before, and 4 h after irradiation). There were no significant differences in the median tumor quadrupling time between groups that received either no treatment or SCF alone, or between groups treated with 10 Gy and SCF or 10 Gy alone (P > 0.05). These results are encouraging and suggest that SCF does not stimulate tumor cell proliferation in vivo or enhance the survival of tumor cells following irradiation.
View details for Web of Science ID A1995RL49300037
View details for PubMedID 7542170
MULTIPLE COURSES OF HIGH-DOSE TOTAL SKIN ELECTRON-BEAM THERAPY IN THE MANAGEMENT OF MYCOSIS-FUNGOIDES
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
1995; 32 (5): 1445-1449
A retrospective analysis was undertaken to determine the indications for, the efficacy of, and the long-term complications of two courses of total skin electron beam therapy for mycosis fungoides.A retrospective analysis of 15 patients with the pathologic diagnosis of mycosis fungoides treated in the Department of Radiation Oncology at Stanford University Medical Center between 1968 and 1990 was performed. All patients received two courses of high-dose electron beam therapy to the skin. The mean dose for the total skin treatment for the first course was 32.6 Gy and 23.4 Gy for the second course of treatment.Following the first course of total skin electron beam therapy, 11 of 15 had a complete response, with a mean duration of 11.6 months. All patients received adjuvant therapies between the first and second courses of high-dose total skin electron beam therapy. The mean interval between the first and the second courses of therapy was 41.3 months. Patients were restaged prior to commencement of their second course of high-dose total skin electron beam therapy, resulting in upstaging in six. The second course of therapy resulted in six complete responses and nine partial responses. Twelve of these patients have since died, 1 is lost to follow-up, and 2 are living with disease. The long-term side effects in the two living patients include pigmentation changes, alopecia, and diffuse xerosis.Delivery of two courses of total skin electron beam therapy is technically feasible, tolerable, and efficacious. The dose to the total skin was reduced for the second course of therapy in all cases. The criteria used to screen patients included initial good response to total skin electron treatment, long disease-free interval, exhaustion of other therapeutic modalities, and generalized skin involvement at relapse. Long-term toxicities were mild in severity and generally consisted of generalized xerosis, scattered telangiectasias, pigmentation changes, and partial alopecia.
View details for Web of Science ID A1995RM87800020
View details for PubMedID 7635786
STEM-CELL FACTOR ENHANCES THE SURVIVAL OF MURINE INTESTINAL STEM-CELLS AFTER PHOTON IRRADIATION
1995; 142 (1): 12-15
Recombinant rat stem cell factor (SCF) has been shown to decrease lethality in mice exposed to total-body irradiation (TBI) in the lower range of lethality through radioprotection of hematopoietic stem cells and acceleration of bone marrow repopulation. This study evaluates the effect of SCF on the survival of the intestinal mucosal stem cell after TBI. This non-hematopoietic stem cell is clinically relevant. Gastrointestinal toxicity is common during and after abdominal and pelvic radiation therapy and limits the radiation dose in these regions. As observed with bone marrow, the administration of SCF to mice prior to TBI enhanced the survival of mouse duodenal crypt stem cells. The maximum enhancement of survival was seen when 100 micrograms/kg of SCF was given intraperitoneally 8 h before irradiation. This regimen increased the survival of duodenal crypt stem cells after 12.0 Gy TBI from 22.5 +/- 0.7 per duodenal cross section for controls to 30.0 +/- 1.7 after treatment with SCF (P = 0.03). The TBI dose producing 50% mortality at 6 days (LD50/6) was increased from 14.9 Gy for control mice to 19.0 Gy for mice treated with SCF (dose modification factor = 1.28). These findings demonstrate that SCF has radioprotective effects on a non-hematopoietic stem cell population and suggest that SCF may be of clinical value in preventing radiation injury to the intestine.
View details for Web of Science ID A1995QP25100002
View details for PubMedID 7534934
Radioimmunotherapy of the Non-Hodgkin's Lymphomas.
Seminars in radiation oncology
1995; 5 (4): 331–41
Radioimmunotherapy (RIT) is a promising new therapeutic modality for the treatment of non-Hodgkin's lymphoma. General principles of RIT are discussed and the various monoclonal antibodies (MAB) and radionuclides used to date in clinical trials are reviewed. Important determinants of radiolabeled MAB biodistribution include spleen size, tumor burden, and the preinfusion or coinfusion of unlabeled MAB. Clinical trials using RIT for the treatment of non-Hodgkin's lymphoma are summarized. The results from these trials are promising and show that a variety of MAB, radionuclides, and study designs have resulted in high response rates with a number of durable partial and complete responses at both myeloablative and nonmyeloablative doses in patients with recurrent or refractory disease. Determinants of efficacy and toxicity are discussed and the dosimetry of RIT is reviewed. The biology of RIT and relative efficacy of RIT compared with conventional external bean radiation therapy is discussed. Areas of active research and approaches for increasing the therapeutic index of RIT are reviewed. Important areas of future research are discussed that may ultimately potentiate efficacy and decrease the toxicity of RIT, and help determine how to optimally combine RIT with other therapeutic modalities.
View details for DOI 10.1054/SRAO00500331
View details for PubMedID 10717155
STEM-CELL FACTOR ENHANCES THE SURVIVAL OF IRRADIATED HUMAN BONE-MARROW MAINTAINED IN SCID MICE
1994; 12 (4): 430-435
The effect of recombinant human stem cell factor (SCF) on the response of human fetal bone marrow progenitor cells to irradiation was studied using immunodeficient mice with human fetal bone grafts (SCID/Hu mice). SCID/Hu mice were treated with three intraperitoneal injections of 500 micrograms/kg SCF at 20 h before, two h before, and four h after 100 cGy total body irradiation. Fourteen days following irradiation, the fetal bone grafts were harvested and studied. Most of the isolated bone marrow cells were human, as determined by flow cytometry. Colony forming assays were performed on the bone marrow to determine the survival of erythroid (BFU-E) and myeloid (CFU-GM) precursor cells. A statistically significant increase in BFU-E and CFU-GM survival after irradiation was observed for bone marrow maintained in the SCF treated mice when compared to bone marrow from mice not treated with SCF. The enhancement in colony forming unit survival after irradiation ranged from 4.3-fold for BFU-E (p = 0.05) to 13.1-fold for CFU-GM (p = 0.002). These findings suggest that SCF may be of potential clinical value for the prevention of radiation-induced myelosuppression.
View details for Web of Science ID A1994NY15600010
View details for PubMedID 7524895
ORGAN MODELING IN THE QUANTITATION OF PLANAR IMAGES FOR DISTRIBUTION STUDIES
9th Conference on Radioimmunodetection and Radioimmunotherapy of Cancer
JOHN WILEY & SONS INC. 1994: 919–22
The advantage of whole-body imaging for distribution studies is that it accounts for all activities. The problem, however, is that the classic approach to determining distribution from planar images does not accommodate overlapping structures. That approach assumes implicitly that the sampling region is a prismoid whose cross-section, parallel to the detector plane, is defined by a region of interest and whose sides are orthogonal to the detector plane.In the proposed organ-model approach, the region of interest is assumed explicitly to be the projected shadow of an organ or structure, whose general shape is known from anatomic generality, and whose size or specific shape variation is defined by the shadow or region of interest. If "j" is a pixel in the organ shadow "i", a fraction "Vij" of the volume of organ "i" is assumed to project orthogonally in "j". More than one organ shadow can overlap, in which case the volumes projecting in "j" are the sum of "Vij" over "i". The activity "Aj" (count rate density) in any location "j" is defined by the linear combination of volumes "Vij" and concentrations "Ci". For all the pixels in the image, this defines an overdetermined set of linear equations that can be solved by matrix inversion for "Ci", the organ concentrations.The organ-model method was tested on simulated and phantom data. It proved, on serial and repeat processing, to be robust (not subject to large errors due to small variations) if the images had sufficient contrast. This method was found to be superior to the classic approach in evaluating the same data, because in the classic approach, the border regions are too heavily weighted, and therefore, the size of the sampling region is critical. Furthermore, the expression of the results in concentrations is more relevant to dosimetry, the derivation of which is based on cumulative concentrations.Modeling organ shadows is a viable improvement on the use of regions of interest to quantify tracer distribution in planar imaging.
View details for Web of Science ID A1994MV41800025
View details for PubMedID 8306280
EFFECT OF FILGRASTIM (G-CSF) IN HODGKINS-DISEASE PATIENTS TREATED WITH RADIATION
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
1994; 28 (2): 445-450
To evaluate the effect of filgrastim (recombinant human G-CSF) on radiation-induced neutropenia in a well defined, homogenous patient population.Seven patients who were to receive large field subdiaphragmatic irradiation after thoracic "mantle" fields for treatment of Hodgkin's disease entered this study. They received daily subcutaneous (SC) injections of filgrastim during subdiaphragmatic irradiation. Total white blood cell (WBC) and absolute neutrophil cell (ANC) counts were measured and compared to a historical series of patients, and hematological toxicity was assessed. The endpoints of the study were nadir WBC and ANC counts and time to WBC and ANC recovery.Compared to the historical series, filgrastim significantly increased the WBC and ANC throughout the period of subdiaphragmatic irradiation. Nadir WBC (5.98 +/- 1.24/mm3) and ANC (4.71 +/- 1.07/mm3) in the Filgrastim group were approximately two times those of the historical series (3.32 +/- 1.06/mm3 and 2.39 +/- 0.97/mm3 respectively; p < 0.002). Nadir platelet counts were not affected by filgrastim therapy. Three of seven patients reported mild musculoskeletal pain, but there was no other apparent toxicity.Compared to the historical series, filgrastim therapy significantly increased WBC and ANC during extended field radiation therapy and was well tolerated. It may be clinically useful in other groups of patients who are likely to develop profound neutropenia during large field irradiation.
View details for Web of Science ID A1994MP98100015
View details for PubMedID 7506247
THE HYPOXIC CYTOTOXIN SR-4233 INCREASES THE EFFECTIVENESS OF RADIOIMMUNOTHERAPY IN MICE WITH HUMAN NON-HODGKINS-LYMPHOMA XENOGRAFTS
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
1994; 28 (1): 119-126
To determine if either the hypoxic cell radiosensitizer etanidazole (SR 2508) or the hypoxic cytotoxin SR 4233 could improve the effectiveness of radioimmunotherapy.LC4 (an IgG1 monoclonal antibody directed toward malignant T cells) and MB-1 (an irrelevant isotype-matched control antibody) were injected intraperitoneally into severe combined immunodeficient phenotype mice with human cutaneous T cell lymphoma xenografts in order to determine the distribution of the antibodies in the tumors and normal tissues as a function of time. Computerized-pO2-histography was used to measure the median oxygen tension in the tumors. Tumor-bearing mice were treated with: (a) LC4; (b) 90Y-LC4; (c) 90Y-MB-1; (d) whole body irradiation delivered via an external 137Cs source; (e) etanidazole and 90Y-LC4; (f) SR 4233 and 90Y-LC4; (g) etanidazole; and (h) SR 4233. An additional group of mice received no treatment and served as controls. A tumor growth delay assay was used to assess the effectiveness of the different treatment regimens.LC4 accumulated in the tumors to a significantly greater extent than MB-1 (p < 0.001) and reached a peak concentration in the tumors 5 days post-injection. The human cutaneous T cell lymphoma xenografts had a relatively low median oxygen tension. LC4 by itself was able to produce a minor decrease in tumor size (control vs. LC4; p = 0.001). 90Y-LC4 produced greater tumor growth delay than LC4 alone (LC4 vs. 90Y-LC4; p = 0.01); however, the Yttrium-90 caused neutropenia and weight loss. The 90Y-labeled tumor-specific and non-specific antibodies both exerted greater tumor growth delay than externally delivered whole body irradiation (p < or = 0.03) due to preferential uptake of the antibodies in the tumors. Etanidazole and SR 4233 by themselves did not significantly inhibit the growth of the tumors. Etanidazole did not significantly enhance the tumor growth delay produced by 90Y-LC4 (90Y-LC4 vs etanidazole and 90Y-LC4, p = 0.13). SR 4233, on the other hand, did enhance the tumor growth delay produced by 90Y-LC4 (90Y-LC4 vs. SR 4233 and 90Y-LC4, p = 0.046). The neutropenia and weight loss caused by 90Y-LC4 were exacerbated slightly (< 10%) by the administration of SR 4233.A first generation hypoxic cytotoxin, SR 4233, was able to enhance the tumor growth delay produced by radioimmunotherapy in severe combined immunodeficient phenotype mice with human cutaneous T cell lymphoma xenografts.
View details for Web of Science ID A1994MP35300016
View details for PubMedID 8270432
DETERMINANTS OF LOW-DOSE RATE EFFECTS ASSOCIATED WITH RADIOIMMUNOTHERAPY
ANTIBODY IMMUNOCONJUGATES AND RADIOPHARMACEUTICALS
1993; 6 (3): 197-207
View details for Web of Science ID A1993LW35500005
THE EFFECT OF STEM-CELL FACTOR ON IRRADIATED HUMAN BONE-MARROW
1993; 53 (17): 3857-3859
This study evaluates the effect of recombinant human stem cell factor (SCF) on the in vitro response of human bone marrow progenitor cells to irradiation. Light density nonadherent mononuclear cells were isolated from human bone marrow and resuspended in either semisolid culture or liquid culture with or without 100 ng/ml SCF. After 24 h in culture, cells were irradiated and assessed for survival of erythroid burst-forming unit, granulocyte colony-forming unit(s), or granulocyte-macrophage colony-forming unit precursors in the presence of erythropoietin, granulocyte colony-stimulating factor, or granulocyte-macrophage colony-stimulating factor, respectively. Incubation with SCF prior to irradiation (0-300 cGy) resulted in an increase in both absolute colony number and surviving fraction for erythroid burst-forming units, granulocyte colony-forming units, and granulocyte-macrophage colony-forming units as compared to cultures that did not contain SCF. The mean surviving fraction enhancement ratio after 100 cGy ranged from 1.2 to 3.7. An increased fraction of CD34+ progenitors in S-phase after exposure to SCF may explain in part the apparent radioprotective effect of SCF on human bone marrow progenitor cells.
View details for Web of Science ID A1993LU57900003
View details for PubMedID 7689418
CORRELATION OF TUMOR SENSITIVITY TO LOW-DOSE-RATE IRRADIATION WITH G2/M-PHASE BLOCK AND OTHER RADIOBIOLOGICAL PARAMETERS
1993; 135 (1): 24-31
The efficacy of exponentially decreasing low-dose-rate irradiation was compared with that of equivalent doses of multiply fractionated high-dose-rate external-beam irradiation in mice with three different kinds of tumors that varied in terms of alpha/beta ratio, tumor volume doubling times, and cell cycle times. Cell cycle distribution was measured after low-dose-rate and high-dose-rate irradiation. The relative efficacy of low-dose-rate irradiation versus equivalent doses of high-dose-rate irradiation was correlated with the extent of arrest of cells in G2 phase of the cell cycle. Unlike 38C13 murine B-cell lymphoma, neither the HT29 human colorectal xenograft or the SNB75 human glioblastoma xenograft was significantly more sensitive to low-dose-rate than fractionated high-dose-rate irradiation. The 38C13 B-cell lymphoma also had the shortest tumor volume doubling and cell cycle times, the most G2 arrest after low-dose-rate irradiation, more G2 arrest with low-dose-rate than high-dose-rate irradiation, and the highest alpha/beta ratio. The data presented here support the hypothesis that dose-rate effects may be minimal for tumors with small shoulders and large alpha/beta ratios and that arrest of cells in G2 phase plays an important role in cell death mediated by low-dose-rate irradiation. The proliferative rates of tumor cells may modify dose-rate effects further, and the interaction of all of these factors may explain in part the increased efficacy of low-dose-rate irradiation and radioimmunotherapy compared with high-dose-rate irradiation that has been reported in some animal models.
View details for Web of Science ID A1993LM85600003
View details for PubMedID 8327657
LOCAL HYPERTHERMIA AND SR-4233 ENHANCE THE ANTITUMOR EFFECTS OF RADIOIMMUNOTHERAPY IN NUDE-MICE WITH HUMAN COLONIC ADENOCARCINOMA XENOGRAFTS
1993; 53 (13): 3022-3027
Local hyperthermia and the hypoxic cytotoxin SR 4233 were administered to nude mice with 693 +/- 47 mm3 (mean +/- SE) s.c. HCT-8 human colonic adenocarcinoma xenografts in an attempt to enhance the antitumor effects of radioimmunotherapy. Biodistribution studies revealed preferential binding of NR-Lu-10, a murine monoclonal antibody, to the tumors compared with an isotype-matched control antibody, CCOO16-3.A single injection of 25 microCi 90Y-NR-Lu-10 significantly inhibited tumor growth (control versus 90Y-NR-Lu-10: P = 0.048). The administration of hyperthermia at 41.5 degrees C for 1 h immediately following the injection of 111In-labeled NR-Lu-10 up-regulated tumor-associated antigen expression and increased antibody uptake in the tumors by 73% (P = 0.001) without significantly affecting antibody uptake in normal tissues. However, the heat treatment did not produce a more homogeneous distribution of the antibodies in the tumors and did not significantly enhance the tumor growth delay produced by 90Y-NR-Lu-10 (P = 0.07). The administration of local hyperthermia at 43.0 degrees C for 1 h, on the other hand, had direct cytotoxic effects (P = 0.03) and enhanced the tumor growth delay produced by 90Y-NR-Lu-10 (P = 0.01). SR 4233 also enhanced the tumor growth delay produced by 90Y-NR-Lu-10 (P = 0.03). The greatest antitumor effects were observed when both hyperthermia at 43.0 degrees C and SR 4233 were administered in combination with 90Y-NR-Lu-10 (P = 0.002). No toxicity was produced by the local hyperthermia, and the only toxicities produced by 90Y-NR-Lu-10 and SR 4233 were neutropenia and weight loss.
View details for Web of Science ID A1993LL13100018
View details for PubMedID 8319209
RADIOBIOLOGY OF RADIOLABELED ANTIBODY THERAPY AS APPLIED TO TUMOR DOSIMETRY
1993; 20 (2): 601-610
This paper reviews the radiobiological aspects of radioimmunotherapy (RIT) with radiolabeled antibodies, including comparisons between RIT and external beam irradiation. The effectiveness of cell killing by radiation decreases with the dose rate and the rate of decrease is determined by the size of the shoulder on the radiation survival curve. Tumors with poor repair capabilities exhibit less of a dose rate effect than tumors with good repair capabilities. Continued tumor cell proliferation during treatment occurs at very low dose rates and can contribute to the reduced effectiveness of low dose rate radiation. Toxicity to normal tissues will determine the total dose of radiolabeled antibody that can be given and this will be influenced by the choice of both the radionuclide and the antibody. The reported enhanced effectiveness of RIT may be due to multiple factors including selective targeting of cells responsible for tumor volume doubling, tumor surface binding rather than homogeneous binding throughout the tumor volume, targeting of the tumor vasculature, or block of cell cycle progression in G2. During RIT, there is less time for reoxygenation of hypoxic tumor cells than during a course of conventional external beam radiotherapy. It has not yet been determined whether this will have a detrimental effect on RIT. Probably the most important factor in the success of RIT is dose heterogeneity. Any viable portion of a tumor that is not targeted and does not receive a significant radiation dose will potentially lead to treatment failure, no matter how high the dose received by the remainder of the tumor. Comparisons between RIT and external beam radiation have shown a wide range of relative efficacy. Tumors most likely to respond to RIT are tumors with poor repair capabilities, tumors that are susceptible to blockage in radiosensitive phases of the cell cycle, tumors that reoxygenate rapidly, and tumors that express the relevant antigen homogeneously. From a radiobiological perspective, it appears that RIT alone is unlikely to cure many tumors and that combination with other treatment modalities will be essential.
View details for Web of Science ID A1993KZ77300015
View details for PubMedID 8492769
- Determinants of low dose rate effects associated with radioimmunotherapy. Antibody Immunoconjugates and Radiopharmaceuticals 1993; 6: 197-207
- Response to letter by A. E. Amin regarding tumour size dependence of relative efficacy of radioimmunotherapy and external beam irradiation in tumour treatment. Radiotherapy Oncology 1993; 25: 219-220
THE EFFECT OF UNLABELED MONOCLONAL-ANTIBODY (MAB) ON THE BIODISTRIBUTION OF I-131 ANTIIDIOTYPE MAB IN MURINE B-CELL LYMPHOMA
RADIOTHERAPY AND ONCOLOGY
1992; 24 (3): 169-176
The 38C13 murine B cell lymphoma model was used to study the effect of the preinjection of unlabelled anti-idiotype monoclonal antibody (mAb) on the subsequent biodistribution of 131I-anti-idiotype mAb. Mice with established tumors received 0-500 micrograms of unlabelled anti-idiotype mAb 24 h prior to the administration of 131I-anti-idiotype (specific), or both 125I-anti-idiotype and 131I-isotype-matched irrelevant control (nonspecific) mAb. Mice were counted daily in a gamma counter and sacrificed at 2-144 h following injection. Mice were dissected and the weight and activity of the animals and organs were measured. Mice were bled periodically and circulating idiotype levels were measured using an ELISA assay. Five hundred micrograms of unlabelled anti-idiotype mAb increased the retention time of the specific but not the nonspecific mAb in all organs and tumor. Following pretreatment with unlabelled mAb, the cumulative tumor/whole body and tumor/normal organ ratios became similar to those of the nonspecific mAb, with concentration ratios (specific/nonspecific mAb) of approximately 1, which persisted until 96 h post injection when circulating idiotype reappears in antigen excess. In the absence of unlabelled mAb there was less retention in tumor and normal tissue. This is presumed to be due in part to decreased levels of circulating 131I-mAb secondary to rapid plasma clearance of antigen-antibody complexes and tumor cell mediated dehalogenation, which results when the specific mAb specifically binds the targeted antigen. Thus, the addition of unlabelled mAb increased the retention by decreasing the specific behavior of the anti-idiotypic antibody.
View details for Web of Science ID A1992JL59000005
View details for PubMedID 1410571
OVERVIEW OF ANIMAL STUDIES COMPARING RADIOIMMUNOTHERAPY WITH DOSE EQUIVALENT EXTERNAL BEAM IRRADIATION
RADIOTHERAPY AND ONCOLOGY
1992; 23 (2): 111-117
As the field of radioimmunotherapy (RIT) continues to develop and looks increasingly promising, there is growing interest in the radiobiology of RIT. Recently, several investigators have conducted studies in animal models comparing the relative efficacy of RIT with dose equivalent external beam irradiation. Although these studies are the first of many to follow, the results are provocative and several patterns are suggested by the available data. The results of the studies are summarized and compared, and preliminary hypotheses that might explain the reported observations are discussed. In summary, results from studies comparing the efficacy of RIT with external beam irradiation have been variable and may be indicative of different underlying mechanisms. While the particular experimental model, design and methodology used to compare the efficacy of RIT with external beam irradiation are probably important influences upon subsequent observations, it appears that for a given tumor type, the size of the survival curve shoulder or alpha/beta ratio, and tumor doubling time are important determinants of the magnitude of the dose rate effect. When this effect is minimal, it is possible that other factors such as reoxygenation, the arrest of cells in G2, and selective targeting of tumor by radiolabelled antibody may explain, in part, the increased efficacy of RIT compared with external beam irradiation that has been observed in some systems.
View details for Web of Science ID A1992HJ27900007
View details for PubMedID 1546186
- THE BIODISTRIBUTION OF IN-111 ANTI-BFGF IN A VARIETY OF TUMORS - CORRELATION WITH CELL-BINDING ASSAYS ANNALS OF THE NEW YORK ACADEMY OF SCIENCES 1991; 638: 497-502
RESULTS OF THE 1989 ASSOCIATION OF RESIDENTS IN RADIATION ONCOLOGY SURVEY
31ST ANNUAL MEETING OF THE AMERICAN SOC OF THERAPEUTIC RADIOLOGY AND ONCOLOGY
PERGAMON-ELSEVIER SCIENCE LTD. 1991: 1363–67
To assess a variety of issues concerning physician-trainees in radiation oncology, a survey was conducted by the Association of Residents in Radiation Oncology (ARRO). Ultimately, 70% of residents responded to the survey. The survey identified perceived strengths as well as shortcomings in training programs. We conclude that residents are generally satisfied with their training. Future surveys are planned to expand this important database.
View details for Web of Science ID A1991FQ58100027
View details for PubMedID 2045310
- MYCOSIS-FUNGOIDES ARTHROPATHY ANNALS OF INTERNAL MEDICINE 1991; 114 (7): 571-572
OBSERVATIONS ON THE EFFECT OF CHIMERIC ANTI-CD4 MONOCLONAL-ANTIBODY IN PATIENTS WITH MYCOSIS-FUNGOIDES
1991; 77 (1): 20-30
Chimeric (murine/human) anti-CD4 monoclonal antibody was infused into seven patients with mycosis fungoides. Successive patients received doses of 10, 20, 40, and 80 mg of antibody twice a week for 3 consecutive weeks. All patients had some clinical improvement, but responses were of relatively short duration. Serum levels of chimeric antibody varied as a function of dose. At the 80-mg dose level, antibody was readily observed in biopsied skin lesions. Although there was coating by antibody of most CD4 positive cells in the blood, there was no significant depletion of CD4 positive cells. Low-level antibody responses against the mouse Ig variable region and human Ig allotypic constant region determinants were observed in several patients, but none were of clinical significance. All but two patients made primary antibody and T-cell proliferative responses to a simultaneously administered foreign protein test antigen. However, there was marked suppression of the mixed lymphocyte reaction. We conclude that at the dose levels studied, a chimeric anti-CD4 monoclonal antibody (1) had some clinical efficacy against mycosis fungoides; (2) was well tolerated; (3) had a low level of immunogenicity; (4) had immediate immunosuppressive effects; and (5) did not induce tolerance to a co-injected antigen.
View details for Web of Science ID A1991EQ04100003
View details for PubMedID 1984796
THE BIODISTRIBUTION OF IN-111 ANTI-BFGF IN A VARIETY OF TUMORS - CORRELATION WITH CELL-BINDING ASSAYS
CONF ON THE FIBROBLAST GROWTH FACTOR FAMILY
NEW YORK ACAD SCIENCES. 1991: 497–502
View details for Web of Science ID A1991BW41G00072
DETERMINANTS OF THE ANTITUMOR EFFECT OF RADIOLABELED MONOCLONAL-ANTIBODIES
1990; 50 (16): 4935-4940
The murine B-cell lymphoma 38C13 model was used to study the radiobiological effect of 131I-monoclonal antibody (MAB) therapy compared with dose equivalent external beam irradiation. Continuous exponentially decreasing low dose rate (LDR) gamma-irradiation, and multiply fractionated (MF) X-irradiation were compared with dose equivalent 131I-MAB. The relative therapeutic efficacy of radioimmunotherapy, and the relative contribution of (a) low dose rate; (b) whole body irradiation; and (c) microdosimetry to the overall effect were determined. Groups of mice with or without B-cell lymphoma were treated with either (a) 131I-anti-idiotype MAB; (b) 131I-isotype-matched irrelevant control MAB; (c) 5-15 Gy 250 kV X-irradiation given as a single fraction; (d) 2.5-30 Gy 250 kV X-irradiation given in 10 fractions/2 weeks; or by (e) continuous exponentially decreasing gamma-irradiation via a 137Cs source, which simulated the effective t1/2 of the 131I-MAB. In tumor-free mice the LD50/30 was approximately 10 Gy for MF and LDR external irradiation, and 11-12 Gy for 131I-MAB. However, the effect of these modes of irradiation on tumor size differed significantly. The cumulative percentage of tumor reduction averaged over 12 days was 0.635 +/- 0.055%/Gy for MF, and 1.36 +/- 0.061%/Gy for LDR external irradiation (a relative efficacy factor of 1.63 for LDR irradiation; P = 0.01). Assuming homogeneous body distribution, the tumor reduction effect over 12 days for 131I-MAB was 2.064 +/- 0.133%/Gy for specific, and 1.742 +/- 0.1%/Gy for nonspecific isotype-matched irrelevant 131I-MAB (P = 0.02). When 131I-MAB was compared to LDR external irradiation, the relative efficacy factor was 1.99 (P less than 0.001). In summary, there was a dose rate effect on tumor response, which may in part explain the efficacy of radioimmunotherapy. The additional effect of 131I-MAB on tumor response was only partially explained by the cumulative concentration ratio of 131I-MAB tumor/131I-MAB whole body, which was on average 1.7. This relatively low concentration ratio was partly due to tumor-mediated dehalogenation. Thus, the overall tumor response was a function of the total dose, dose rate, and both the specific and nonspecific distribution of 131I-MAB.
View details for Web of Science ID A1990DT62000020
View details for PubMedID 2379158
- THE CHANGING FACE OF RADIATION ONCOLOGY SOUTHERN MEDICAL JOURNAL 1990; 83 (4): 488-488
HYPERTHERMIA AND RADIATION-THERAPY IN THE TREATMENT OF RECURRENT MERKEL CELL TUMORS
1988; 62 (8): 1479-1486
A high incidence of local recurrence, spread to regional lymph nodes, and distant metastases has been reported after surgical excision of Merkel cell tumors (MCT). The use of postoperative radiation therapy and/or chemotherapy is reviewed from the literature. Despite adjuvant treatment, local tumor recurrences frequently develop. Two patients are presented with metastatic MCT recurrent in previously irradiated sites who had excellent clinical responses and local control following retreatment with local hyperthermia in conjunction with low to moderate dose radiation therapy. These patients represent the first reported use of hyperthermia in the management of MCT. The encouraging local responses described suggest a potential role for the use of hyperthermia and concomitant radiation therapy in the treatment of recurrent MCT.
View details for Web of Science ID A1988Q277400005
View details for PubMedID 3048629
2 INDEPENDENT PATHWAYS OF HELPER ACTIVITY PROVIDED BY A SINGLE T-CELL CLONE
JOURNAL OF IMMUNOLOGY
1986; 136 (1): 34-38
Data presented in this paper demonstrate the existence of two separate pathways by which a single T cell clone can induce B cell differentiation. With the use of high doses of antigen, a T cell clone can induce a primary antibody response in unprimed B cells. With the use of low doses of antigen, the same T cell clone can induce an immunoglobulin (Ig)G response in primed B cells. The primary response is accompanied by T cell proliferation and lymphokine production (interleukin 2, B cell growth factor, B cell differentiation factor for immunoglobulin M, and B cell differentiation factor for immunoglobulin G). The secondary response does not require proliferation and occurs independently of detectable lymphokine production. Variants of the wild type T cell helper clone have been isolated. One variant can provide help to unprimed B cells when high doses of antigen are used. This variant cannot provide help to primed B cells when low doses of antigen are used, nor can it provide help to CBA/N "xid" B cells at any antigen concentration tested. Additional variants have been isolated that proliferate on antigen-pulsed-presenting cells, but fail to secrete detectable lymphokines and do not induce B cell differentiation. These results suggest that a single T cell helper clone has multiple functional activities that can be independently expressed.
View details for Web of Science ID A1986AWM4600007
View details for PubMedID 2933466
EFFECT OF THYMOPOIETIN AND INTERLEUKIN-2 ON DEPRESSED MITOGENIC RESPONSIVENESS AND COLONY FORMATION OF LYMPHOCYTES FROM PATIENTS WITH PRELEUKEMIA
1986; 8 (1-2): 33-44
Previously, cloning efficiencies and mitogenic responsiveness of lymphocytes from patients with preleukemic disorders were shown to be significantly depressed. Whole blood T lymphocyte colony formation and 3H-TdR incorporation were used to assess the effects of interleukin-2 (IL-2) and thymopoietin (TP-5) on the proliferation of lymphocytes from patients with preleukemia. There were no statistically significant differences (p greater than 0.05) between any of the test groups stimulated with mitogen alone when compared to groups stimulated with mitogen plus TP-5 and/or IL-2 in either assay system for either patient or control groups. Nevertheless, TP-5 and IL-2 markedly increased the cloning efficiency and mitogenic responsiveness of lymphocytes from many of the patients studied, but in no case restored the proliferation response to the level of mitogen stimulated control lymphocytes. These findings suggest that other soluble mediators/factors may be needed to fully compensate for deficient mitogenic responsiveness and colony formation of lymphocytes from patients with preleukemic disorders which may be multifactoria in origin. Of importance, enhancement of lymphocyte responsiveness to PHA/Con-A with TP-5 and IL-2 suggests the presence of maturational/functional defects in lymphocytes from some of these patients which may be compensated for in part by addition of TP-5 and IL-2.
View details for Web of Science ID A1986C572400004
View details for PubMedID 3487854
- RELATION OF AGE TO LYMPHOCYTE RADIOSENSITIVITY INVITRO HEALTH PHYSICS 1984; 46 (2): 431-433
STUDIES OF LYMPHOCYTES-T IN PRELEUKEMIC DISORDERS AND ACUTE NONLYMPHOCYTIC LEUKEMIA - INVITRO RADIOSENSITIVITY, MITOGENIC RESPONSIVENESS, COLONY FORMATION, AND ENUMERATION OF LYMPHOCYTIC SUBPOPULATIONS
1983; 61 (3): 449-455
Tritiated thymidine incorporation in a whole blood lymphocyte stimulation test (LST) and lymphocyte colony formation (CFU-L) from whole blood were measured following in vitro x-irradiation. Lymphocytes from patients with myelodysplastic disorders, acute nonlymphocytic leukemia, and patients at increased risk for leukemia because of their primary disease and/or cytotoxic therapy were found to be significantly more sensitive to in vitro x-irradiation than lymphocytes from clinically normal individuals. Cloning efficiencies and mitogenic responsiveness of patient lymphocytes were significantly depressed as compared to normal values. Using monoclonal antibodies to specific surface markers, quantitative abnormalities in lymphocytic subpopulations from myelodysplastic patients also were observed. These findings are suggestive of a defect at the T-cell level that may directly or indirectly affect hematopoiesis.
View details for Web of Science ID A1983QF62600007
View details for PubMedID 6600631
LYMPHOCYTE ABNORMALITIES IN PRELEUKEMIA .1. DECREASED NK ACTIVITY, ANOMALOUS IMMUNOREGULATORY CELL SUBSETS AND DEFICIENT EBV RECEPTORS
1983; 7 (3): 389-395
The development of acute non-lymphocytic leukemia is preceded by a set of symptoms described as the preleukemia syndrome. Six patients who fulfilled the criteria for this preleukemia syndrome have been evaluated for abnormalities in the lymphocyte population. The NK cell activity was reduced, the immunoregulatory cell populations were numerically abnormal, and the B cell subpopulation was deficient in EBV receptors. Thus, in addition to the abnormalities in the myeloid populations, there are serious defects in the lymphoid systems of preleukemic patients.
View details for Web of Science ID A1983RG90300008
View details for PubMedID 6310273
RADIATION-INDUCED INHIBITION OF HUMAN-LYMPHOCYTE BLASTOGENESIS - THE EFFECT OF SUPEROXIDE-DISMUTASE AND CATALASE
INTERNATIONAL JOURNAL OF RADIATION BIOLOGY
1982; 41 (3): 283-294
Mitogen-induced lymphocyte blastogenesis was measured following X-irradiation (0-4 Gy) in the presence or absence of superoxide dismutase (SOD), under aerobic and anaerobic conditions. There were no significant differences between radiation survival curves under these different conditions, nor did SOD have any radioprotective effect. This demonstrates the lack of oxygen dependence of radiation-induced inhibition of lymphocyte blastogenesis. Following X-irradiation at 2 Gy, neither SOD nor catalase, alone or together, added before or after irradiation, were radioprotective. In comparison to controls, both enzymes depressed lymphocyte proliferation when added at levels as low as 25 microgram catalase or 100 microgram SOD/ml media. When SOD and catalase were added together, the greatest depression of blastogenesis was obtained with increasing levels of SOD relative to increasing levels of catalase, indicating that SOD was largely responsible for this depression. The suppressive effect of administration of SOD (p less than 0.05), catalase (p less than 0.001) and SOD + catalase (p less than 0.001) on lymphocyte division was significantly greater when given prior to X-irradiation. The lack of an oxygen effect and the inability of SOD and catalase to protect human lymphocytes from X-irradiation suggest that 2- and /or H2O2 are not involved in radiation-induced inhibition of lymphocyte blastogenesis.
View details for Web of Science ID A1982NH71100004
View details for PubMedID 6978318
Growth of macrophage colonies from normal canine peripheral blood: morphological, cytochemical and functional parameters.
1982; 1 (6): 325-344
Canine macrophage colonies were grown at high colony-forming efficiencies (average of 4.5 macrophage colonies/10(4) mononuclear cells plated) from gradient-separated peripheral blood mononuclear cells. The colonies were first observed on day 5 of the culture period, reached maximum numbers between days 10-14, and differed kinetically from CFU-GM colonies. Colony cells had typical macrophage morphology at the cellular and ultrastructural levels, were nonspecific-esterase positive, specific-esterase negative, and were actively phagocytic. Colony growth in semisolid cultures and 3H-TdR incorporation in liquid cultures occurred following stimulation with rabbit anti-canine immunoglobulin antisera (anti-Ig), anti-bovine serum albumin and normal rabbit serum. Addition of 2-mercaptoethanol (2-Me) to stimulated cultures significantly enhanced the proliferative response. A maximal response was obtained using anti-IgM and 2-ME. Preincubation of anti-Ig with goat anti-rabbit IgG or purified canine immunoglobulin in the presence or absence of 2-ME significantly reduced the proliferative response, suggesting the presence of both specific and nonspecific components of stimulation. The growth of canine macrophage colonies from peripheral blood provides a method for non-invasive, sequential and kinetic studies of macrophage progenitor cells in large animals.
View details for PubMedID 6983153
- ASSESSMENT OF THE INVITRO RADIOSENSITIVITY OF HUMAN PERIPHERAL-BLOOD LYMPHOCYTES RADIATION RESEARCH 1982; 89 (3): 575-589
GROWTH OF HUMAN LYMPHOCYTE-T COLONIES FROM WHOLE-BLOOD - CULTURE REQUIREMENTS AND APPLICATIONS
JOURNAL OF CELLULAR BIOCHEMISTRY
1982; 18 (1): 15-24
Growth of human lymphocyte colonies from whole blood following stimulation with PHA, Con A, or PPD is described. Individual colony cells were identified as T lymphocytes on the basis of surface marker and enzyme cytochemical characterizations. Colony formation increased as a power function over a wide range of cell concentrations above a critical minimal concentration. The whole blood culture system eliminates possible selective effects of lymphocyte colony techniques utilizing gradient-enriched lymphocyte fractions and more closely approximates the in vivo milieu. The whole blood colony method is more sensitive for the detection of low-level radiation effects on lymphocytes than widely used tests that measure 3H-thymidine incorporation. In preliminary studies, we used the whole blood method to determine the relative radiosensitivity of lymphocytes from humans with various hematopoietic disorders, and observed abnormalities in mitogen responsiveness and colony formation in some of the patient groups. This method has wide application for studies in cellular and clinical immunology.
View details for Web of Science ID A1982NK16800002
View details for PubMedID 6978345
CYTOGENETICS AND GRANULOPOIETIC EFFECTS OF BONE-MARROW FIBROBLASTIC CELLS IN FANCONIS ANEMIA
BRITISH JOURNAL OF HAEMATOLOGY
1981; 48 (1): 85-93
To determine if abnormalities exist in the bone marrow stroma in Fanconi's anaemia, we studied the cytogenetic composition of in vitro bone marrow fibroblastic cells (FC) from a patient with this disorder and compared it to those obtained from skin fibroblasts, peripheral blood lymphocytes, and direct bone marrow preparations. The presence of granulocytic progenitors in bone marrow and T lymphocyte colonies in peripheral blood was also determined in addition to the ability of this patient's FC to stimulate normal granulocytic progenitors. We found that the FC had far fewer chromosomal abnormalities and stimulated normally the growth of granulocyte colonies. Granulocyte progenitors were not found, but T lymphocyte colonies were abundant. These results support the concept that a defect in haematopoietic stromal elements is not responsible for the aplasia developing in the disorder.
View details for Web of Science ID A1981LR28200011
View details for PubMedID 7248193
INCREASED RADIOSENSITIVITY OF A SUB-POPULATION OF LYMPHOCYTE-T PROGENITORS FROM PATIENTS WITH FANCONI ANEMIA
1981; 57 (6): 1043-1048
In vitro radiation survival of peripheral blood T lymphocytes was studied in 15 clinically normal adults and 4 patients with Fanconi's anemia. Tritiated thymidine incorporation in a whole blood lymphocyte stimulation test (LST) and a newly developed whole blood T-lymphocyte colony assay were used to measure lymphocyte blastogenesis and colony formation in response to phytohemagglutinin (PHA) or concanavalin-A (Con-A) stimulation. Lymphocyte colony formation was found to be consistently more sensitive than the LST for detection of low-level radiation effects using both normal cells and lymphocytes from Fanconi's anemia patients. Lymphocytes from patients with Fanconi's anemia were significantly more sensitive to in vitro x-irradiation than lymphocytes from clinically normal individuals as measured by their ability to divide when stimulated by PHA in the LST (patients, D37 = 198 R; normals, D37 = 309 R, p = 0.057) and colony formation assay (patients, D37 = 53 R; normals, D37 = 109 R, p = 0.016). No significant difference in the radiosensitivity of the Con-A response was observed between the two groups. The PHA-responsive T-lymphocyte subpopulation in Fanconi's anemia patients appears to be intrinsically defective. The nature of this defect, significance in the disease process, and relevancy of these findings to the establishment of radiation protection standards are discussed.
View details for Web of Science ID A1981LT01600008
View details for PubMedID 6971665
THE SELECTIVE GROWTH OF HUMAN LYMPHOCYTE-T COLONIES FROM WHOLE-BLOOD IN A SEMISOLID CULTURE SYSTEM
1981; 9 (9): 926-937
Human T lymphocyte colonies may be selectively grown from whole blood in a single phase semisolid culture system following stimulation with PHA-P, Con-A, or PPD. This technique eliminates the requirement for gradient-enriched lymphocyte fractions, and provides a sensitive system for the study of T lymphocyte progenitors that more closely approximates the in vivo milieu. Whole blood colonies were composed of lymphoblasts and mature lymphocytes. Individual colony cells, identified as T lymphocytes, lacked lipase and specific esterase activity, formed E rosettes, did not phagocytize latex beads, and were largely ANAE positive. Whole blood was plated at a final concentration of 3%. Optimal mitogen/antigen concentrations were 125 microgram Con-A, 80 microgram PHA-P and 50 microgram PPD/ml culture media. Peak colony growth occurred between days 7 and 8. Colony formation increased as a power function over a wide range of cell concentrations (5 x 10(3)-5 x 10(4) lymphocytes plated). Maximal whole blood colony formation occurred when 5 x 10(4)-10(5) lymphocytes were plated. There was a significant increase in the cloning efficiency using whole blood as compared to gradient-separated cells. This method has wide application for the study of radiation effects, lymphocyte alterations in various disease states, antigen recognition, and the induction and amplification of T cell function.
View details for Web of Science ID A1981ML45700005
View details for PubMedID 6978263
- Cell-mediated immunity in the dog in relation to disease: A review. Comp Immun Microbiol Infect Dis 1980; 2: 405-415
A WHOLE-BLOOD TECHNIQUE FOR THE QUANTITATION OF CANINE LYMPHOCYTE-T PROGENITORS USING A SEMISOLID CULTURE SYSTEM
1980; 8 (8): 1031-1039
A whole blood technique is described for the growth of concanavalin A (Con A) stimulated canine lymphocyte colonies in semisolid medium. By eliminating the routine Ficoll-Paque (F-P) gradient lymphocyte isolation, this method avoids potential problems of growth modulation due to elimination of non-lymphoid accessory cells and the influences on colony formation associated with the selective effects of F-P on lymphocyte subpopulations. Thus, the technique more closely approximates the in vivo milieu. The whole-blood method also produces higher cloning efficiencies than methods using gradient isolation of lymphocytes. Studies over a wide range of blood concentration produced a linear response of in vitro colony formation although extrapolation of the cell-dose colony-response curve did not intersect zero. Mitogen titration data indicates that a relatively large dose of Con A is required for whole blood colony formation compared to the standard F-P method. The colonies ultrastructurally were composed of lymphoblastic and lymphocytic elements which were negative for non-specific esterase activity. Characterization of cells retrieved from the colonies using rosetting techniques indicates a high percentage of the colony cells relative to canine peripheral blood cells form rosettes with human erythrocytes.
View details for Web of Science ID A1980KJ80500010
View details for PubMedID 6970675
- Susceptibility of clinical isolates of Pseudomonas aeruginosa to antimicrobial agents. Pharmacol Ther 1979; 2: 275-278
PHARMACOKINETICS OF PENICILLIN-G IN TURKEY
AMERICAN JOURNAL OF VETERINARY RESEARCH
1978; 39 (7): 1219-1221
Parmacokinetics of penicillin G was determined for the turkey. The study was prompted by the isolation of a sulfonamide-resistant strain of Pasteurella multocida from tissues of turkeys involved in an outbreak of fowl cholera and the subsequent discovery that little pharmacologic information was available concerning other antimicrobial agents in that species. Penicillin G was chosen for study because P multocida is susceptible to this antibiotic. The elimination of the antibiotic followed first-order kinetics, and the half-life was found to be 0.5 hours. Parenteral administration of benzathine-procaine penicillin G resulted in higher concentrations, which persisted for longer periods than did procaine or potassium salts of the antibiotic.
View details for Web of Science ID A1978FF86100028
View details for PubMedID 677541