- Hematology/Oncology/Stem Cell Transplant, Pediatric
- Oncology (Cancer), Pediatric
- AML, childhood and adolescent/young adult
- ALL, childhood and adolescent/young adult
- lymphoblastic lymphoma, childhood
- Pediatric Hematology-Oncology
Member, Cancer Center (2007 - Present)
Myeloid Steering Committee, Children's Oncology Group (2007 - Present)
Director, Pediatric Oncology Experimental Therapeutics Investigators' Consortium [POETIC] (2019 - Present)
Honors & Awards
Member, Alpha Omega Alpha (1990)
New Approaches in Pediatric Myeloid Leukemia, V Foundation (10/09-09/12)
Banking Acute Leukemia Specimens at Lucile Packard Childrens Hospital: Hyundai Infrastructure Grant, Hyundai Foundation (10/11-09/12)
Molecular and Pharmacologic Correlates of Acute Myeloid Leukemia in Down Syndrome, NIH ROI subcontract from Wayne State University (01/09-04/16)
Board Certification: American Board of Pediatrics, Pediatric Hematology-Oncology (1996)
Medical Education: University of California at San Francisco School of Medicine (1989) CA
Internship: UCSF Medical Center (1990) CA
Residency: UCSF Medical Center (1992) CA
Fellowship: Stanford University Medical Center (1995) CA
MD, U.C., San Francisco, Medicine (1989)
BA, U. C., Berkeley, Biochemistry (1985)
Current Research and Scholarly Interests
Pediatric Hematology/Oncology, Phase I drug studies for refractory and relapsed leukemia; genomic studies, biologic risk-stratification and treatment of acute myeloid leukemia; prediction or induction response and risk of relapse using phosphoproteomics in childhood AML; novel MRD techniques in childhood ALL.
A Study Evaluating the Safety, Tolerability, Pharmacokinetics and Preliminary Activity of Idasanutlin in Combination With Either Chemotherapy or Venetoclax in the Treatment of Pediatric and Young Adult Participants With Relapsed/Refractory Acute Leukemias or Solid Tumors
This is a Phase I/II, multicenter, open-label, multi-arm study designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of idasanutlin, administered as a single agent or in combination with chemotherapy or venetoclax, in pediatric and young adult participants with acute leukemias or solid tumors. This study is divided into three parts: Part 1 will begin with dose escalation of idasanutlin as a single agent in pediatric participants with relapsed or refractory solid tumors to identify the maximum tolerated dose (MTD)/maximum administered dose (MAD) and to characterize dose-limiting toxicities (DLTs). Following MTD/MAD identification, three separate safety run-in cohorts in neuroblastoma, acute myeloid leukemia (AML), and acute lymphoblastic leukemia (ALL) will be conducted to identify the recommended Phase 2 dose (RP2D) of idasanutlin in each combination, with chemotherapy or venetoclax. Part 2 will evaluate the safety and early efficacy of idasanutlin in combination with chemotherapy or venetoclax in newly enrolled pediatric and young adult participants in neuroblastoma, AML,and ALL cohorts at idasanutlin RP2D. Part 3 will potentially be conducted as an additional expansion phase of the idasanutlin combination cohorts in neuroblastoma, AML, or ALL for further response and safety assessment.
A Study to Test the Safety and Efficacy of the Drug Larotrectinib for the Treatment of Tumors With NTRK-fusion in Children
The study is being done to test the safety of a cancer drug called larotrectinib in children. The cancer must have a change in a particular gene (NTRK1, NTRK2 or NTRK3). Larotrectinib blocks the actions of these NTRK genes in cancer cells and can therefore be used to treat cancer. The first study part (Phase 1) is done to determine what dose level of larotrectinib is safe for children, how the drug is absorbed and changed by their bodies and how well the cancer responds to the drug. The main purpose of the second study part (Phase 2) is to investigate how well and how long different cancer types respond to the treatment with larotrectininb.
A Trial of Epigenetic Priming in Patients With Newly Diagnosed Acute Myeloid Leukemia
The overall aim of this study is to determine if epigenetic priming with a DNA methyltransferase inhibitor (DMTi) prior to chemotherapy blocks is tolerable and carries evidence of a clinical efficacy signal as determined by minimal residual disease (MRD), event-free survival (EFS), and overall survival (OS). Tolerability for each of the agents, as well as total reduction in DNA methylation and outcome assessments will be done to simultaneously obtain preliminary biological and clinical data for each DMTi in parallel. PRIMARY OBJECTIVES: - Evaluate the tolerability of five days of epigenetic priming with azacitidine and decitabine as a single agent DMTi prior to standard AML chemotherapy blocks. - Evaluate the change in genome-wide methylation burden induced by five days of epigenetic priming and the association of post-priming genome-wide methylation burden with event-free survival among pediatric AML patients. SECONDARY OBJECTIVES - Describe minimal residual disease levels following Induction I chemotherapy in patients that receive DMTi. - Estimate the event-free survival and overall survival of patients receiving a DMTi prior to chemotherapy courses.
Carfilzomib in Combination With Cyclophosphamide and Etoposide for Children
This study evaluates the use of carfilzomib in combination with cyclophosphamide and etoposide for children with relapsed/refractory solid tumors or leukemia. The medications cyclophosphamide and etoposide are standard drugs often used together for the treatment of cancer in children with solid tumors or leukemia. Carfilzomib is FDA (Food and Drug Administration) approved in the United States for adults with multiple myeloma (a type of cancer). However, this drug is not approved to treat children with relapsed/refractory solid tumors or leukemia. With this research, we plan to determine the DLTs and MTD of Carfilzomib given in combination with cyclophosphamide and etoposide in pediatric patients with relapsed/refractory leukemias and solid tumors.
Dose Escalation Study of CLR 131 in Children, Adolescents, and Young Adults With Relapsed or Refractory Malignant Tumors Including But Not Limited to Neuroblastoma, Rhabdomyosarcoma, Ewings Sarcoma, and Osteosarcoma
The study evaluates CLR 131 in children, adolescents, and young adults with relapsed or refractory malignant solid tumors and lymphoma and recurrent or refractory malignant brain tumors for which there are no standard treatment options with curative potential.
Phase I Dose Escalation Study of CD19/CD22 Chimeric Antigen Receptor (CAR) T Cells in Children and Young Adults With Recurrent or Refractory B Cell Malignancies
This phase I trial studies the best dose and side effects of CD19/CD22 chimeric antigen receptor (CAR) T cells when given together with chemotherapy, and to see how well they work in treating children or young adults with CD19 positive B acute lymphoblastic leukemia that has come back or does not respond to treatment. A CAR is a genetically-engineered receptor made so that immune cells (T cells) can attack cancer cells by recognizing and responding to the CD19/CD22 proteins. These proteins are commonly found on B acute lymphoblastic leukemia. Drugs used in chemotherapy, such as fludarabine phosphate and cyclophosphamide, work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving CD19/CD22-CAR T cells and chemotherapy may work better in treating children or young adults with B acute lymphoblastic leukemia.
Protocol for Collecting, Banking and Distributing Human Tissue Samples: St. Jude Children's Research Hospital Tissue Resources Core Facility
The aims of this protocol are: to collect and store diseased and normal tissue and body fluid samples from new and returning patients at St. Jude Children's Research Hospital (SJCRH), affiliated sites and collaborating institutions; to collect and store samples from relatives of SJCRH patients; to collect and store retrospective and prospective pertinent corresponding clinical and laboratory data on disease characterization, treatment, and outcome; and to serve as a source of human biological samples and corresponding laboratory and clinical data.
Safety and Dose Finding Study of Neratinib in Children and Young Adults With Cancer That Has Returned or Not Responded to Treatment
The purpose of this study is to test the safety of neratinib at different dose levels and to find out what effects, good and bad, it has on the patients and the cancer.
Study of Venetoclax in Combination With Chemotherapy in Pediatric Patients With Refractory or Relapsed Acute Myeloid Leukemia or Acute Leukemia of Ambiguous Lineage
The purpose of this study is to test the safety and determine the best dose of venetoclax and cytarabine when given with or without idarubicin in treating pediatric patients with acute myeloid leukemia (AML) that did not respond to treatment (refractory) or has come back after treatment (relapsed). PRIMARY OBJECTIVE: Determine a tolerable combination of venetoclax plus chemotherapy in pediatric patients with relapsed or refractory AML or acute leukemia of ambiguous lineage. The primary endpoints are the recommended phase 2 doses (RP2D) of venetoclax plus cytarabine and venetoclax plus cytarabine and idarubicin. SECONDARY OBJECTIVE: Estimate the overall response rate to the combination of venetoclax and chemotherapy in pediatric patients with relapsed or refractor AML or acute leukemia of ambiguous lineage. The secondary endpoints are the rates of complete remission (CR) and complete remission with incomplete count recovery (CRi) for patients treated at the RP2D.
Total Therapy for Infants With Acute Lymphoblastic Leukemia (ALL) I
The purpose of this study is to test the good and bad effects of the study drugs bortezomib and vorinostat when they are given in combination with chemotherapy commonly used to treat acute lymphoblastic leukemia (ALL) in infants. For example, adding these drugs could decrease the number of leukemia cells, but it could also cause additional side effects. Bortezomib and vorinostat have been approved by the US Food and Drug Administration (FDA) to treat other cancers in adults, but they have not been approved for treating children with leukemia. With this research, we plan to meet the following goals: PRIMARY OBJECTIVE: - Determine the tolerability of incorporating bortezomib and vorinostat into an ALL chemotherapy backbone for newly diagnosed infants with ALL. SECONDARY OBJECTIVES: - Estimate the event-free survival and overall survival of infants with ALL who are treated with bortezomib and vorinostat in combination with an ALL chemotherapy backbone. - Measure minimal residual disease (MRD) positivity using both flow cytometry and PCR. - Compare end of induction, end of consolidation, and end of reinduction MRD levels to Interfant99 (ClinicalTrials.gov registration ID number NCT00015873) participant outcomes.
Total Therapy XVII for Newly Diagnosed Patients With Acute Lymphoblastic Leukemia and Lymphoma
The overarching objective of this study is to use novel precision medicine strategies based on inherited and acquired leukemia-specific genomic features and targeted treatment approaches to improve the cure rate and quality of life of children with acute lymphoblastic leukemia (ALL) and acute lymphoblastic lymphoma (LLy). Primary Therapeutic Objectives: - To improve the event-free survival of provisional standard- or high-risk patients with genetically or immunologically targetable lesions or minimal residual disease (MRD) ≥ 5% at Day 15 or Day 22 or ≥1% at the end of Remission Induction, by the addition of molecular and immunotherapeutic approaches including tyrosine kinase inhibitors or chimeric antigen receptor (CAR) T cell / blinatumomab for refractory B-acute lymphoblastic leukemia (B-ALL) or B-lymphoblastic lymphoma (B-LLy), and the proteasome inhibitor bortezomib for those lacking targetable lesions. - To improve overall treatment outcome of T acute lymphoblastic leukemia (T-ALL) and T-lymphoblastic lymphoma (T-LLy) by optimizing pegaspargase and cyclophosphamide treatment and by the addition of new agents in patients with targetable genomic abnormalities (e.g., activated tyrosine kinases or JAK/STAT mutations) or by the addition of bortezomib for those who have a poor early response to treatment but no targetable lesions, and by administering nelarabine to T-ALL and T-LLy patients with leukemia/lymphoma cells in cerebrospinal fluid at diagnosis or MRD ≥0.01% at the end of induction. - To determine in a randomized study design whether the incidence and/or severity of acute vincristine-induced peripheral neuropathy can be reduced by decreasing the dosage of vincristine in patients with the high-risk CEP72 TT genotype or by shortening the duration of vincristine therapy in patients with the CEP72 CC or CT genotype. Secondary Therapeutic Objectives: - To estimate the event-free survival and overall survival of children with acute lymphoblastic leukemia (ALL) and acute lymphoblastic lymphoma (LLy). - To determine the tolerability of combination therapy with ruxolitinib and Early Intensification therapy in patients with activation of JAK-STAT signaling that can be inhibited by ruxolitinib and Day 15 or Day 22 MRD ≥5%, Day 42 MRD ≥1%, or LLy patients without complete response at the End of Induction and all patients with early T cell precursor leukemia. Biological Objectives: - To use data from clinical genomic sequencing of diagnosis, germline/remission and MRD samples to guide therapy, including incorporation of targeted agents and institution of genetic counseling and cancer surveillance. - To evaluate and implement deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) sequencing-based methods to monitor levels of MRD in bone marrow, blood, and cerebrospinal fluid. - To assess clonal diversity and evolution of pre-leukemic and leukemic populations using DNA variant detection and single-cell genomic analyses in a non-clinical, research setting. - To identify germline or somatic genomic variants associated with drug resistance of ALL cells o conventional and newer targeted anti-leukemic agents in a non- clinical, research setting. - To compare drug sensitivity of ALL cells from diagnosis to relapse in vitro and in vivo and determine if acquired resistance to specific agents is related to specific somatic genome variants that are not detected or found in only a minor clone at initial diagnosis. Supportive Care Objectives - To conduct serial neurocognitive monitoring of patients and to evaluate the benefits of a computer-based cognitive intervention. - To evaluate the impact of low-magnitude high frequency mechanical stimulation on bone mineral density and markers of bone turnover. Exploratory Objectives: - To identify pharmacogenetic, pharmacokinetic and pharmacodynamic predictors of treatment outcome. - To perform a detailed assessment of thiopurine metabolism and 6-mercaptopurine (6MP) tolerance, toxicity, and treatment outcome. - To establish xenografts of representative subtypes of ALL. - To prospectively determine the risk and epidemiology of breakthrough infection or febrile neutropenia and adverse effects of antibiotics. - To use cell phenotyping and genomic approaches to characterize the non-tumor microenvironment and correlate with responses to conventional and immunotherapeutic approaches. - To estimate the treatment response and event-free survival and overall survival of children with mixed phenotype acute leukemia (MPAL) when ALL diagnostic and treatment approaches are used.
Efficacy and Safety of Decitabine as Epigenetic Priming With Induction Chemotherapy in Pediatric Acute Myelogenous Leukemia (AML) Subjects
The purpose of this study is to provide data on the activity of a standard daunorubicin, cytarabine, and etoposide (ADE) induction plus epigenetic priming with decitabine as assessed by standard measures of complete remission (CR), leukemia free survival (LFS) and overall survival (OS), as well as, on minimal residual disease (MRD). It will also provide necessary data on the safety and Pharmacokinetics (PK) of decitabine in pediatric patients that is currently unavailable.
Stanford is currently not accepting patients for this trial.
Genome, Proteome and Tissue Microarray in Childhood Acute Leukemia
We will study gene and protein expression in leukemia cells of children diagnosed with acute leukemia. We hope to identify genes or proteins which can help us grade leukemia at diagnosis in order to: (a) develop better means of diagnosis and (b) more accurately choose the best therapy for each patient.
Stanford is currently not accepting patients for this trial. For more information, please contact Norman J Lacayo, 650-723-5535.
- Independent Studies (5)
A comprehensive circulating tumor DNA assay for detection of translocation and copy number changes in pediatric sarcomas.
Molecular cancer therapeutics
Most circulating tumor DNA (ctDNA) assays are designed to detect recurrent mutations. Pediatric sarcomas share few recurrent mutations but rather are characterized by translocations and copy number changes. We applied CAncer Personalized Profiling by deep Sequencing (CAPP-Seq) for detection of translocations found in the most common pediatric sarcomas. We also applied ichorCNA to the combined off-target reads from our hybrid capture to simultaneously detect copy number alterations. We analyzed 64 prospectively collected plasma samples from 17 pediatric sarcoma patients. Translocations were detected in the pre-treatment plasma of 13 patients and were confirmed by tumor sequencing in 12 patients. Two of these patients had evidence of complex chromosomal rearrangements in their ctDNA. We also detected copy number changes in the pre-treatment plasma of 7 patients. We found that ctDNA levels correlated with metastatic status and clinical response. Furthermore, we detected rising ctDNA levels before relapse was clinically apparent, demonstrating the high sensitivity of our assay. This assay can be utilized for simultaneous detection of translocations and copy number alterations in the plasma of pediatric sarcoma patients. While we describe our experience in pediatric sarcomas, this approach can be applied to other tumors that are driven by structural variants.
View details for DOI 10.1158/1535-7163.MCT-20-0987
View details for PubMedID 34353895
Activated Natural Killer Cells Predict Poor Clinical Prognosis in High-risk B- and T- cell Acute Lymphoblastic Leukemia.
B- and T- cell acute lymphoblastic leukemia (B/T-ALL) may be refractory or recur after therapy by suppressing host anti-cancer immune surveillance mediated specifically by natural killer (NK) cells. We delineated the phenotypic and functional defects in NK cells of high-risk B/T-ALL patients using mass, flow, and in silico cytometry, with the goal of further elucidating the role of NK cells in sustaining ALL regression. We found that, compared to normal counterparts, NK cells in B/T-ALL patients are less cytotoxic, but exhibit an activated signature characterized by high CD56, high CD69, production of activated NK-origin cytokines, and calcium signaling. We demonstrated that defective maturation of NK cells into cytotoxic effectors prevents NK cells of ALL patients from lysing NK-sensitive targets as efficiently as normal NK cells. Additionally, we showed that NK cells in ALL are exhausted, which is likely caused by their chronic activation. We found that increased frequencies of activated cytokine-producing NK cells are associated with increased disease severity and independently predict poor clinical outcome in ALL patients. Our studies highlight the benefits of developing NK cell profiling as a diagnostic tool to predict clinical outcome in patients with ALL and underscore the clinical potential of allogeneic NK infusions to prevent ALL recurrence.
View details for DOI 10.1182/blood.2020009871
View details for PubMedID 34077953
Engineered Type 1 Regulatory T Cells Have a Cytotoxic Profile and Kill Pediatric Acute Myeloid Leukemia Cells
CELL PRESS. 2021: 317
View details for Web of Science ID 000645188700642
Venetoclax and Navitoclax in Combination with Chemotherapy in Patients with Relapsed or Refractory Acute Lymphoblastic Leukemia and Lymphoblastic Lymphoma.
Combining venetoclax, a selective BCL-2 inhibitor, with low-dose navitoclax, a BCL-XL/BCL-2 inhibitor, may allow targeting of both BCL-2 and BCL XL without dose-limiting thrombocytopenia associated with navitoclax monotherapy. The safety and preliminary efficacy of venetoclax with low-dose navitoclax and chemotherapy was assessed in this phase I dose escalation study (NCT03181126) in pediatric and adult patients with relapsed/refractory acute lymphoblastic leukemia or lymphoblastic lymphoma. Forty-seven patients received treatment. A recommended phase II dose of 50 mg navitoclax for adults and 25 mg for patients <45 kg with 400 mg adult-equivalent venetoclax was identified. Delayed hematopoietic recovery was the primary safety finding. The complete remission rate was 60%, including responses in patients who had previously received hematopoietic cell transplantation or immunotherapy. Thirteen patients (28%) proceeded to transplantation or CAR T-cell therapy on study. Venetoclax with navitoclax and chemotherapy was well tolerated and had promising efficacy in this heavily pretreated patient population.
View details for DOI 10.1158/2159-8290.CD-20-1465
View details for PubMedID 33593877
Safety, pharmacokinetics, and pharmacodynamics of panobinostat in children, adolescents, and young adults with relapsed acute myeloid leukemia.
BACKGROUND: Novel therapies are urgently needed for pediatric patients with relapsed acute myeloid leukemia (AML).METHODS: To determine whether the histone deacetylase inhibitor panobinostat could be safely given in combination with intensive chemotherapy, a phase 1 trial was performed in which 17 pediatric patients with relapsed or refractory AML received panobinostat (10, 15, or 20 mg/m2 ) before and in combination with fludarabine and cytarabine.RESULTS: All dose levels were tolerated, with no dose-limiting toxicities observed at any dose level. Pharmacokinetic studies demonstrated that exposure to panobinostat was proportional to the dose given, with no associations between pharmacokinetic parameters and age, weight, or body surface area. Among the 9 patients who had sufficient (>2%) circulating blasts on which histone acetylation studies could be performed, 7 demonstrated at least 1.5-fold increases in acetylation. Although no patients had a decrease in circulating blasts after single-agent panobinostat, 8 of the 17 patients (47%), including 5 of the 6 patients treated at dose level 3, achieved complete remission. Among the 8 complete responders, 6 (75%) attained negative minimal residual disease status.CONCLUSIONS: Panobinostat can be safely administered with chemotherapy and results in increased blast histone acetylation. This suggests that it should be further studied in AML.
View details for DOI 10.1002/cncr.33156
View details for PubMedID 32809242
Extracellular Vesicle and Particle Biomarkers Define Multiple Human Cancers.
There is an unmet clinical need for improved tissue and liquid biopsy tools for cancer detection. We investigated the proteomic profile of extracellular vesicles and particles (EVPs) in 426 human samples from tissue explants (TEs), plasma, and other bodily fluids. Among traditional exosome markers, CD9, HSPA8, ALIX, and HSP90AB1 represent pan-EVP markers, while ACTB, MSN, and RAP1B are novel pan-EVP markers. To confirm that EVPs are ideal diagnostic tools, we analyzed proteomes of TE- (n= 151) and plasma-derived (n= 120) EVPs. Comparison of TE EVPs identified proteins (e.g., VCAN, TNC, and THBS2) that distinguish tumors from normal tissues with 90% sensitivity/94% specificity. Machine-learning classification of plasma-derived EVP cargo, including immunoglobulins, revealed 95% sensitivity/90% specificity in detecting cancer. Finally, we defined a panel of tumor-type-specific EVP proteins in TEs and plasma, which can classify tumors of unknown primary origin. Thus, EVP proteins can serve as reliable biomarkers for cancer detection and determining cancer type.
View details for DOI 10.1016/j.cell.2020.07.009
View details for PubMedID 32795414
Integrative analysis of whole-genome and RNA sequencing in high-risk pediatric malignancies
AMER ASSOC CANCER RESEARCH. 2020: 90–91
View details for Web of Science ID 000551367400129
Comparative gene expression analysis for identification and prioritization of therapeutic targets in a cohort of childhood cancers
AMER ASSOC CANCER RESEARCH. 2020: 66
View details for Web of Science ID 000551367400088
- Delayed cancer diagnoses and high mortality in children during the COVID-19 pandemic. Pediatric blood & cancer 2020: e28427
Metabolomics in acute myeloid leukemia.
Molecular genetics and metabolism
Acute myeloid leukemia (AML) is a complex, heterogenous hematological malignancy caused by mutations in myeloid differentiation and proliferation. Response to therapy and long-term outcomes vary widely based on chromosomal and molecular aberrations. Many platforms have been used to characterize and stratify AML. Metabolomics, the global profiling of small molecules in a biological sample, has emerged in the last decade as an important tool for studying the metabolic dependency of cancer cells. Metabolic reprogramming is not only an important manifestation of AML but clinically relevant for diagnosis, risk stratification and targeted drug development. In this review, we discuss notable metabolic studies of the last decade and their application to novel therapies.
View details for DOI 10.1016/j.ymgme.2020.05.005
View details for PubMedID 32457018
Venetoclax in combination with cytarabine with or without idarubicin in children with relapsed or refractory acute myeloid leukaemia: a phase 1, dose-escalation study.
The Lancet. Oncology
BACKGROUND: Outcomes for children with relapsed or refractory acute myeloid leukaemia remain poor. The BCL-2 inhibitor, venetoclax, has shown promising activity in combination with hypomethylating agents and low-dose cytarabine in older adults for whom chemotherapy is not suitable with newly diagnosed acute myeloid leukaemia. We aimed to determine the safety and explore the activity of venetoclax in combination with standard and high-dose chemotherapy in paediatric patients with relapsed or refractory acute myeloid leukaemia.METHODS: We did a phase 1, dose-escalation study at three research hospitals in the USA. Eligible patients were aged 2-22 years with relapsed or refractory acute myeloid leukaemia or acute leukaemia of ambiguous lineage with adequate organ function and performance status. During dose escalation, participants received venetoclax orally once per day in continuous 28-day cycles at either 240 mg/m2 or 360 mg/m2, in combination with cytarabine received intravenously every 12 h at either 100 mg/m2 for 20 doses or 1000 mg/m2 for eight doses, with or without intravenous idarubicin (12 mg/m2) as a single dose, using a rolling-6 accrual strategy. The primary endpoint was the recommended phase 2 dose of venetoclax plus chemotherapy and the secondary endpoint was the proportion of patients treated at the recommended phase 2 dose who achieved complete remission or complete remission with incomplete haematological recovery. Analyses were done on patients who received combination therapy. The study is registered with ClinicalTrials.gov (NCT03194932) and is now enrolling to address secondary and exploratory objectives.FINDINGS: Between July 1, 2017, and July 2, 2019, 38 patients were enrolled (aged 3-22 years; median 10 [IQR 7-13]), 36 of whom received combination therapy with dose escalation, with a median follow-up of 7·1 months (IQR 5·1-11·2). The recommended phase 2 dose of venetoclax was found to be 360 mg/m2 (maximum 600 mg) combined with cytarabine (1000 mg/m2 per dose for eight doses), with or without idarubicin (12 mg/m2 as a single dose). Overall responses were observed in 24 (69%) of the 35 patients who were evaluable after cycle 1. Among the 20 patients treated at the recommended phase 2 dose, 14 (70%, 95% CI 46-88) showed complete response with or without complete haematological recovery, and two (10%) showed partial response. The most common grade 3-4 adverse events were febrile neutropenia (22 [66%]), bloodstream infections (six [16%]), and invasive fungal infections (six [16%]). Treatment-related death occurred in one patient due to colitis and sepsis.INTERPRETATION: The safety and activity of venetoclax plus chemotherapy in paediatric patients with heavily relapsed and refractory acute myeloid leukaemia suggests that this combination should be tested in newly diagnosed paediatric patients with high-risk acute myeloid leukaemia.FUNDING: US National Institutes of Health, American Lebanese Syrian Associated Charities, AbbVie, and Gateway for Cancer Research.
View details for DOI 10.1016/S1470-2045(20)30060-7
View details for PubMedID 32171069
Repurposing Drugs for Acute Myeloid Leukemia: A Worthy Cause or a Futile Pursuit?
2020; 12 (2)
Acute myeloid leukemia (AML) is a clinically and genetically heterogenous malignancy of myeloid progenitor cells that affects patients of all ages. Despite decades of research and improvement in overall outcomes, standard therapy remains ineffective for certain subtypes of AML. Current treatment is intensive and leads to a number of secondary effects with varying results by patient population. Due to the high cost of discovery and an unmet need for new targeted therapies that are well tolerated, alternative drug development strategies have become increasingly attractive. Repurposing existing drugs is one approach to identify new therapies with fewer financial and regulatory hurdles. In this review, we provide an overview of previously U.S. Food and Drug Administration (FDA) approved non-chemotherapy drugs under investigation for the treatment of AML.
View details for DOI 10.3390/cancers12020441
View details for PubMedID 32069925
EPIGENETIC TARGETING OF TERT-ASSOCIATED GENE EXPRESSION SIGNATURE IN HUMAN NEUROBLASTOMA WITH TERT OVEREXPRESSION.
Neuroblastoma is a deadly pediatric solid tumor with infrequent recurrent somatic mutations. Particularly, the pathophysiology of tumors without MYCN amplification remains poorly defined. Utilizing an unbiased approach, we performed gene set enrichment analysis of RNA-seq data from 498 neuroblastoma patients and revealed a differentially overexpressed gene signature in MYCN non-amplified neuroblastomas with telomerase reverse transcriptase (TERT) gene overexpression and coordinated activation of oncogenic signaling pathways, including E2Fs, Wnt, Myc, and the DNA repair pathway. Promoter rearrangement of the TERT gene juxtaposes the coding sequence to strong enhancer elements, leading to TERT overexpression and poor prognosis in neuroblastoma, but TERT-associated oncogenic signaling remains unclear. ChIP-seq analysis of the human CLB-GA neuroblastoma cells harboring TERT rearrangement uncovered genome-wide chromatin co-occupancy of Brd4 and H3K27Ac and robust enrichment of H3K36me3 in TERT and multiple TERT-associated genes. Brd4 and cyclin-dependent kinases (CDKs) had critical regulatory roles in the expression and chromatin activation of TERT and multiple TERT-associated genes. Epigenetically targeting Brd4 or CDKs with their respective inhibitors suppressed the expression of TERT and multiple TERT-associated genes in neuroblastoma with TERT overexpression or MYCN amplification. ChIP-seq and ChIP-qPCR provided evidence that the CDK inhibitor directly inhibited Brd4 recruitment to activate chromatin globally. Therefore, inhibiting Brd4 and CDK concurrently with AZD5153 and dinaciclib would be most effective in tumor growth suppression, which we demonstrated in neuroblastoma cell lines, primary human cells, and xenografts. In summary, we describe a unique mechanism in neuroblastoma with TERT overexpression and an epigenetically targeted novel therapeutic strategy.
View details for DOI 10.1158/0008-5472.CAN-19-2560
View details for PubMedID 31900258
Genomic stability at the coding regions of the multidrug transporter gene ABCB1: insights into the development of alternative drug resistance mechanisms in human leukemia cells.
Cancer drug resistance (Alhambra, Calif.)
2020; 3: 959-979
Aim: Despite considerable efforts to reverse clinical multidrug resistance (MDR), targeting the predominant multidrug transporter ABCB1/P-glycoprotein (P-gp) using small molecule inhibitors has been unsuccessful, possibly due to the emergence of alternative drug resistance mechanisms. However, the non-specific P-gp inhibitor cyclosporine (CsA) showed significant clinical benefits in patients with acute myeloid leukemia (AML), which likely represents the only proof-of-principle clinical trial using several generations of MDR inhibitors. Nevertheless, the mutational mechanisms that may underlie unsuccessful MDR modulation by CsA are not elucidated because of the absence of CsA-relevant cellular models. In this study, our aims were to establish CsA-resistant leukemia models and to examine the presence or absence of ABCB1 exonic mutations in these models as well as in diverse types of human cancer samples including AMLs.Methods: Drug-resistant lines were established by stepwise drug co-selection and characterized by drug sensitivity assay, rhodamine-123 accumulation, [3H]-labeled drug export, ABCB1 cDNA sequencing, and RNase protection assay. The genomic stability of the ABCB1 coding regions was evaluated by exome sequencing analysis of variant allele frequencies in human populations. Moreover, the mutational spectrum of ABCB1 was further assessed in diverse types of cancer samples including AMLs in the Cancer Genome Atlas (TCGA) at the National Cancer Institute.Results: We report the development of two erythroleukemia variants, RVC and RDC, which were derived by stepwise co-selection of K562/R7 drug-resistant leukemia cells with the etoposide-CsA and doxorubicin-CsA drug combinations, respectively. Interestingly, both RVC and RDC cell lines, which retained P-gp expression, showed altered multidrug-resistant phenotypes that were resistant to CsA modulation. Strikingly, no mutations were found in the ABCB1 coding regions in these variant cells even under long-term stringent drug selection. Genomically, ABCB1 displayed relatively low variant allele frequencies in human populations when compared with several ABC superfamily members. Moreover, ABCB1 also exhibited a very low mutational frequency in AMLs compared with all types of human cancer. In addition, we found that CsA played a role in undermining the selection of highly drug-resistant cells via induction of low-level and unstable drug resistance.Conclusion: Our data indicate that ABCB1 coding regions are genomically stable and relatively resistant to drug-induced mutations. Non-ABCB1 mutational mechanisms are responsible for the drug-resistant phenotypes in both RVC and RDC cell lines, which are also prevalent in clinical AML patients. Accordingly, we propose several relevant models that account for the development of alternative drug resistance mechanisms in the absence of ABCB1 mutations.
View details for DOI 10.20517/cdr.2020.51
View details for PubMedID 34541464
Pediatric Acute Lymphoblastic Leukemia, Version 2.2020
JOURNAL OF THE NATIONAL COMPREHENSIVE CANCER NETWORK
2020; 18 (1): 81–112
Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Advancements in technology that enhance our understanding of the biology of the disease, risk-adapted therapy, and enhanced supportive care have contributed to improved survival rates. However, additional clinical management is needed to improve outcomes for patients classified as high risk at presentation (eg, T-ALL, infant ALL) and who experience relapse. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for pediatric ALL provide recommendations on the workup, diagnostic evaluation, and treatment of the disease, including guidance on supportive care, hematopoietic stem cell transplantation, and pharmacogenomics. This portion of the NCCN Guidelines focuses on the frontline and relapsed/refractory management of pediatric ALL.
View details for DOI 10.6004/jnccn.2020.0001
View details for Web of Science ID 000506008600011
View details for PubMedID 31910389
Engineered type 1 regulatory T cells designed for clinical use kill primary pediatric acute myeloid leukemia cells
View details for DOI 10.3324/haematol.2020.263129
RSK inhibitor BI-D1870 inhibits acute myeloid leukemia cell proliferation by targeting mitotic exit.
2020; 11 (25): 2387–2403
The 90 kDa Ribosomal S6 Kinase (RSK) drives cell proliferation and survival in cancers, although its oncogenic mechanism has not been well characterized. Phosphorylated level of RSK (T573) was increased in acute myeloid leukemia (AML) patients and associated with poor survival. To examine the role of RSK in AML, we analyzed apoptosis and the cell cycle profile following treatment with BI-D1870, a potent inhibitor of RSK. BI-D1870 treatment increased the G2/M population and induced apoptosis in AML cell lines and patient AML cells. Characterization of mitotic phases showed that the metaphase/anaphase transition was significantly inhibited by BI-D1870. BI-D1870 treatment impeded the association of activator CDC20 with APC/C, but increased binding of inhibitor MAD2 to CDC20, preventing mitotic exit. Moreover, the inactivation of spindle assembly checkpoint or MAD2 knockdown released cells from BI-D1870-induced metaphase arrest. Therefore, we investigated whether BI-D1870 potentiates the anti-leukemic activity of vincristine by targeting mitotic exit. Combination treatment of BI-D1870 and vincristine synergistically increased mitotic arrest and apoptosis in acute leukemia cells. These data show that BI-D1870 induces apoptosis of AML cells alone and in combination with vincristine through blocking mitotic exit, providing a novel approach to overcoming vincristine resistance in AML cells.
View details for DOI 10.18632/oncotarget.27630
View details for PubMedID 32637030
View details for PubMedCentralID PMC7321696
- Establishing a Novel in Vitro Informed Precision Clinical Trial Pathway for Refractory Pediatric Leukemia AMER SOC HEMATOLOGY. 2019
- Safety and Efficacy of Venetoclax in Combination with Navitoclax in Adult and Pediatric Relapsed/Refractory Acute Lymphoblastic Leukemia and Lymphoblastic Lymphoma AMER SOC HEMATOLOGY. 2019
- Venetoclax in Combination with High-Dose Chemotherapy Is Active and Well-Tolerated in Children with Relapsed or Refractory Acute Myeloid Leukemia AMER SOC HEMATOLOGY. 2019
Comparative Tumor RNA Sequencing Analysis for Difficult-to-Treat Pediatric and Young Adult Patients With Cancer.
JAMA network open
2019; 2 (10): e1913968
Importance: Pediatric cancers are epigenetic diseases; therefore, considering tumor gene expression information is necessary for a complete understanding of the tumorigenic processes.Objective: To evaluate the feasibility and utility of incorporating comparative gene expression information into the precision medicine framework for difficult-to-treat pediatric and young adult patients with cancer.Design, Setting, and Participants: This cohort study was conducted as a consortium between the University of California, Santa Cruz (UCSC) Treehouse Childhood Cancer Initiative and clinical genomic trials. RNA sequencing (RNA-Seq) data were obtained from the following 4 clinical sites and analyzed at UCSC: British Columbia Children's Hospital (n=31), Lucile Packard Children's Hospital at Stanford University (n=80), CHOC Children's Hospital and Hyundai Cancer Institute (n=46), and the Pacific Pediatric Neuro-Oncology Consortium (n=24). The study dates were January 1, 2016, to March 22, 2017.Exposures: Participants underwent tumor RNA-Seq profiling as part of 4 separate clinical trials at partner hospitals. The UCSC either downloaded RNA-Seq data from a partner institution for analysis in the cloud or provided a Docker pipeline that performed the same analysis at a partner institution. The UCSC then compared each participant's tumor RNA-Seq profile with more than 11 000 uniformly analyzed tumor profiles from pediatric and young adult patients with cancer, downloaded from public data repositories. These comparisons were used to identify genes and pathways that are significantly overexpressed in each patient's tumor. Results of the UCSC analysis were presented to clinical partners.Main Outcomes and Measures: Feasibility of a third-party institution (UCSC Treehouse Childhood Cancer Initiative) to obtain tumor RNA-Seq data from patients, conduct comparative analysis, and present analysis results to clinicians; and proportion of patients for whom comparative tumor gene expression analysis provided useful clinical and biological information.Results: Among 144 samples from children and young adults (median age at diagnosis, 9 years; range, 0-26 years; 72 of 118 [61.0%] male [26 patients sex unknown]) with a relapsed, refractory, or rare cancer treated on precision medicine protocols, RNA-Seq-derived gene expression was potentially useful for 99 of 144 samples (68.8%) compared with DNA mutation information that was potentially useful for only 34 of 74 samples (45.9%).Conclusions and Relevance: This study's findings suggest that tumor RNA-Seq comparisons may be feasible and highlight the potential clinical utility of incorporating such comparisons into the clinical genomic interpretation framework for difficult-to-treat pediatric and young adult patients with cancer. The study also highlights for the first time to date the potential clinical utility of harmonized publicly available genomic data sets.
View details for DOI 10.1001/jamanetworkopen.2019.13968
View details for PubMedID 31651965
- Combination BCL-2 Inhibitor Therapy with Venetoclax and Navitoclax in Patients with Relapsed/Refractory Acute Lymphoblastic Leukemia and Lymphoblastic Lymphoma CIG MEDIA GROUP, LP. 2019: S184–S185
- Integrative analysis of whole-genome and RNA sequencing in high-risk pediatric malignancies AMER ASSOC CANCER RESEARCH. 2019
Clofarabine Can Replace Anthracyclines and Etoposide in Remission Induction Therapy for Childhood Acute Myeloid Leukemia: The AML08 Multicenter, Randomized Phase III Trial.
Journal of clinical oncology : official journal of the American Society of Clinical Oncology
PURPOSE: To identify effective and less toxic therapy for children with acute myeloid leukemia, we introduced clofarabine into the first course of remission induction to reduce exposure to daunorubicin and etoposide.PATIENTS AND METHODS: From 2008 through 2017, 285 patients were enrolled at eight centers; 262 were randomly assigned to receive clofarabine and cytarabine (Clo+AraC, n = 129) or high-dose cytarabine, daunorubicin, and etoposide (HD-ADE, n = 133) as induction I. Induction II consisted of low-dose ADE given alone or combined with sorafenib or vorinostat. Consolidation therapy comprised two or three additional courses of chemotherapy or hematopoietic cell transplantation. Genetic abnormalities and the level of minimal residual disease (MRD) at day 22 of initial remission induction determined final risk classification. The primary end point was MRD at day 22.RESULTS: Complete remission was induced after two courses of therapy in 263 (92.3%) of the 285 patients; induction failures included four early deaths and 15 cases of resistant leukemia. Day 22 MRD was positive in 57 of 121 randomly assigned evaluable patients (47%) who received Clo+AraC and 42 of 121 patients (35%) who received HD-ADE (odds ratio, 1.86; 95% CI, 1.03 to 3.41; P = .04). Despite this result, the 3-year event-free survival rate (52.9% [44.6% to 62.8%] for Clo+AraC v 52.4% [44.0% to 62.4%] for HD-ADE, P = .94) and overall survival rate (74.8% [67.1% to 83.3%] for Clo+AraC v 64.6% [56.2% to 74.2%] for HD-ADE, P = .1) did not differ significantly across the two arms.CONCLUSION: Our findings suggest that the use of clofarabine with cytarabine during remission induction might reduce the need for anthracycline and etoposide in pediatric patients with acute myeloid leukemia and may reduce rates of cardiomyopathy and treatment-related cancer.
View details for DOI 10.1200/JCO.19.00327
View details for PubMedID 31246522
- Safety and activity of venetoclax in combination with high-dose cytarabine in children with relapsed or refractory acute myeloid leukemia. AMER SOC CLINICAL ONCOLOGY. 2019
A phase II clinical trial of adoptive transfer of haploidentical natural killer cells for consolidation therapy of pediatric acute myeloid leukemia.
Journal for immunotherapy of cancer
2019; 7 (1): 81
Consolidation therapies for children with intermediate- or high-risk acute myeloid leukemia (AML) are urgently needed to achieve higher cure rates while limiting therapy-related toxicities. We determined if adoptive transfer of natural killer (NK) cells from haploidentical killer immunoglobulin-like receptor (KIR)-human leukocyte antigen (HLA)-mismatched donors may prolong event-free survival in children with intermediate-risk AML who were in first complete remission after chemotherapy. Patients received cyclophosphamide (Day -7), fludarabine (Days -6 through -2), and subcutaneous interleukin-2 (Days -1, 1, 3, 5, 7, and 9). Purified, unmanipulated NK cells were infused on Day 0, and NK cell chimerism and phenotyping from peripheral blood were performed on Days 7, 14, 21, and 28. As primary endpoint, the event-free survival was compared to a cohort of 55 patients who completed chemotherapy and were in first complete remission but did not receive NK cells. Donor NK cell kinetics were determined as secondary endpoints. Twenty-one patients (median age at diagnosis, 6.0years [range, 0.1-15.3years]) received a median of 12.5*106 NK cells/kg (range, 3.6-62.2*106 cells/kg) without major side effects. All but 3 demonstrated transient engraftment with donor NK cells (median peak donor chimerism, 4% [range, 0-43%]). KIR-HLA-mismatched NK cells expanded in 17 patients (81%) and contracted in 4 (19%). However, adoptive transfer of NK cells did not decrease the cumulative incidence of relapse (0.393 [95% confidence interval: 0.182-0.599] vs. 0.35 [0.209-0.495]; P=.556) and did not improve event-free (60.7±10.9% vs. 69.1±6.8%; P=.553) or overall survival (84.2±8.5% vs. 79.1±6.6%; P=.663) over chemotherapy alone. The lack of benefit may result from insufficient numbers and limited persistence of alloreactive donor NK cells but does not preclude its potential usefulness during other phases of therapy, or in combination with other immunotherapeutic agents. TRIAL REGISTRATION: www.clinicaltrials.gov , NCT00703820 . Registered 24 June 2008.
View details for DOI 10.1186/s40425-019-0564-6
View details for PubMedID 30894213
Comparative RNA-seq analysis aids in diagnosis of a rare pediatric tumor.
Cold Spring Harbor molecular case studies
2019; 5 (5)
Gliomatosis peritonei is a rare pathologic finding that is associated with ovarian teratomas and malignant mixed germ cell tumors. The occurrence of gliomatosis as a mature glial implant can impart an improved prognosis to patients with immature ovarian teratoma, making prompt and accurate diagnosis important. We describe a case of recurrent immature teratoma in a 10-yr-old female patient, in which comparative analysis of the RNA sequencing gene expression data from the patient's tumor was used effectively to aid in the diagnosis of gliomatosis peritonei.
View details for DOI 10.1101/mcs.a004317
View details for PubMedID 31645344
- Tracking Cell Transplants in Femoral Osteonecrosis with Magnetic Resonance Imaging: A Proof-of-Concept Study in Patients CLINICAL CANCER RESEARCH 2018; 24 (24): 6223–29
- Comparison of the Transcriptomic Signature of Pediatric Vs. Adult CML and Normal Bone Marrow Stem Cells AMER SOC HEMATOLOGY. 2018
- Venetoclax and Navitoclax in Patients with Relapsed or Refractory Acute Lymphoblastic Leukemia and Lymphoblastic Lymphoma AMER SOC HEMATOLOGY. 2018
Tracking Cell Transplants in Femoral Osteonecrosis with Magnetic Resonance Imaging: A Proof of Concept Study in Patients.
Clinical cancer research : an official journal of the American Association for Cancer Research
PURPOSE: Osteonecrosis (ON) is a devastating complication of high dose corticosteroid therapy in cancer patients. Core decompression for prevention of bone collapse has been recently combined with the delivery of autologous concentrated bone marrow aspirates. The purpose of our study was to develop an imaging test for the detection of transplanted bone marrow cells in ON lesions.EXPERIMENTAL DESIGN: In a prospective proof-of-concept clinical trial (NCT02893293), we performed serial MR imaging studies of nine hip joints of seven ON patients before and after core decompression. 24-48hours prior to the surgery, we injected ferumoxytol nanoparticles intravenously to label cells in normal bone marrow with iron oxides. During the surgery, iron labeled bone marrow cells were aspirated from the iliac crest, concentrated and then injected into the decompression track. Following surgery, patients received follow-up MRI up to 6 months after bone marrow cell transplantation.RESULTS: Iron labeled cells could be detected in the access canal by a dark (negative) signal on T2*-weighted MR images. T2* relaxation times of iron labeled cell transplants were significantly lower compared to unlabeled cell transplants of control patients who were not injected with ferumoxytol (P = 0.02). Clinical outcomes of patients who received ferumoxytol-labeled or unlabeled cell transplants were not significantly different (P = 1), suggesting that the added ferumoxytol administration did not negatively affect bone repair.CONCLUSIONS: This immediately clinically applicable imaging test could become a powerful new tool to monitor the effect of therapeutic cells on bone repair outcomes after corticosteroid-induced osteonecrosis.
View details for PubMedID 30224340
Safety and Efficacy of the BCL Inhibitors Venetoclax and Navitoclax in Combination with Chemotherapy in Patients with Relapsed/Refractory Acute Lymphoblastic Leukemia and Lymphoblastic Lymphoma
CIG MEDIA GROUP, LP. 2018: S184–S185
View details for Web of Science ID 000444343400067
- Open-label, dose-escalation, phase 1 study of venetoclax in combination with navitoclax and chemotherapy in patients with relapsed acute lymphoblastic leukemia. AMER SOC CLINICAL ONCOLOGY. 2018
Single-cell developmental classification of B cell precursor acute lymphoblastic leukemia at diagnosis reveals predictors of relapse.
2018; 24 (4): 474–83
Insight into the cancer cell populations that are responsible for relapsed disease is needed to improve outcomes. Here we report a single-cell-based study of B cell precursor acute lymphoblastic leukemia at diagnosis that reveals hidden developmentally dependent cell signaling states that are uniquely associated with relapse. By using mass cytometry we simultaneously quantified 35 proteins involved in B cell development in 60 primary diagnostic samples. Each leukemia cell was then matched to its nearest healthy B cell population by a developmental classifier that operated at the single-cell level. Machine learning identified six features of expanded leukemic populations that were sufficient to predict patient relapse at diagnosis. These features implicated the pro-BII subpopulation of B cells with activated mTOR signaling, and the pre-BI subpopulation of B cells with activated and unresponsive pre-B cell receptor signaling, to be associated with relapse. This model, termed 'developmentally dependent predictor of relapse' (DDPR), significantly improves currently established risk stratification methods. DDPR features exist at diagnosis and persist at relapse. By leveraging a data-driven approach, we demonstrate the predictive value of single-cell 'omics' for patient stratification in a translational setting and provide a framework for its application to human cancer.
View details for PubMedID 29505032
- Single-cell developmental classification of B cell precursor acute lymphoblastic leukemia at diagnosis reveals predictors of relapse NATURE MEDICINE 2018; 24 (4): 474-+
The Significance of Dim Cytoplasmic CD3 Expression in Acute Myeloid Leukemia: A Long-Term Retrospective Study Identifies an Association with Acute Promyelocytic Leukemia with FLT3-ITD Mutations
NATURE PUBLISHING GROUP. 2018: 529
View details for Web of Science ID 000429308603354
The Significance of Dim Cytoplasmic CD3 Expression in Acute Myeloid Leukemia: A Long-Term Retrospective Study Identifies an Association with Acute Promyelocytic Leukemia with FLT3-ITD Mutations
NATURE PUBLISHING GROUP. 2018: 529
View details for Web of Science ID 000459341002354
Niclosamide suppresses acute myeloid leukemia cell proliferation through inhibition of CREB-dependent signaling pathways
2018; 9 (4): 4301–17
CREB (cAMP Response Element Binding protein) is a transcription factor that is overexpressed in primary acute myeloid leukemia (AML) cells and associated with a decreased event-free survival and increased risk of relapse. We recently reported a small molecule inhibitor of CREB, XX-650-23, which inhibits CREB activity in AML cells. Structure-activity relationship analysis for chemical compounds with structures similar to XX-650-23 led to the identification of the anthelminthic drug niclosamide as a potent anti-leukemic agent that suppresses cell viability of AML cell lines and primary AML cells without a significant decrease in colony forming activity of normal bone marrow cells. Niclosamide significantly inhibited CREB function and CREB-mediated gene expression in cells, leading to apoptosis and G1/S cell cycle arrest with reduced phosphorylated CREB levels. CREB knockdown protected cells from niclosamide treatment-mediated cytotoxic effects. Furthermore, treatment with a combination of niclosamide and CREB inhibitor XX-650-23 showed an additive anti-proliferative effect, consistent with the hypothesis that niclosamide and XX-650-23 regulate the same targets or pathways to inhibit proliferation and survival of AML cells. Niclosamide significantly inhibited the progression of disease in AML patient-derived xenograft (PDX) mice, and prolonged survival of PDX mice. Niclosamide also showed synergistic effects with chemotherapy drugs to inhibit AML cell proliferation. While chemotherapy antagonized the cytotoxic potential of niclosamide, pretreatment with niclosamide sensitized cells to chemotherapeutic drugs, cytarabine, daunorubicin, and vincristine. Therefore, our results demonstrate niclosamide as a potential drug to treat AML by inducing apoptosis and cell cycle arrest through inhibition of CREB-dependent pathways in AML cells.
View details for PubMedID 29435104
Improved outcomes for myeloid leukemia of Down syndrome: a report from the Children's Oncology Group AAML0431 trial.
Patients with myeloid leukemia of Down syndrome (ML-DS) have favorable event-free survival (EFS), but experience significant treatment-related morbidity and mortality. ML-DS blast cells ex vivo have increased sensitivity to cytarabine (araC) and daunorubicin, suggesting that optimizing drug dosing may improve outcomes while reducing toxicity. The Children's Oncology Group (COG) AAML0431 trial consisted of 4 cycles of induction and 2 cycles of intensification therapy based on the treatment schema of the previous COG A2971 trial with several modifications. High-dose araC (HD-araC) was used in the second induction cycle instead of the intensification cycle, and 1 of 4 daunorubicin-containing induction cycles was eliminated. For 204 eligible patients, 5-year EFS was 89.9% and overall survival (OS) was 93.0%. The 5-year OS for 17 patients with refractory/relapsed leukemia was 34.3%. We determined the clinical significance of minimal residual disease (MRD) levels as measured by flow cytometry on day 28 of induction I. MRD measurements, available for 146 of the 204 patients, were highly predictive of treatment outcome; 5-year disease-free survival for MRD-negative patients (n = 125) was 92.7% vs 76.2% for MRD-positive patients (n = 21) (log-rank P = .011). Our results indicated that earlier use of HD-araC led to better EFS and OS in AAML0431 than in past COG studies. A 25% reduction in the cumulative daunorubicin dose did not impact outcome. MRD, identified as a new prognostic factor for ML-DS patients, can be used for risk stratification in future clinical trials. This trial was registered at www.clinicaltrials.gov as #NCT00369317.
View details for DOI 10.1182/blood-2017-01-764324
View details for PubMedID 28389462
The Significance of CD56 Expression and the RAM Immunophenotype, a Recurrent Immunophenotype Seen in Children, in Adult Acute Myeloid Leukemia
NATURE PUBLISHING GROUP. 2017: 358A–359A
View details for Web of Science ID 000393724401713
The Significance of Morphologic Dysplasia in 432 Cases of Acute Lymphoblastic Leukemia and Acute Leukemia of Ambiguous Lineage: Correlation with Cytogenetic, Immunophenotypic, and Molecular Findings
NATURE PUBLISHING GROUP. 2017: 376A
View details for Web of Science ID 000393724401782
A Detailed Multi parameter Flow Cytometry Study of 365 Cases of B-Lymphoblastic Leukemia with Subtyping According to the 2016 WHO: A Single Institutional Study
NATURE PUBLISHING GROUP. 2017: 376A
View details for Web of Science ID 000393724401781
Detailed Multiparameter Flow Cytometry Study of 365 Cases of B-Lymphoblastic Leukemia with Subtyping According to the 2016 WHO: A Single Institutional Study
NATURE PUBLISHING GROUP. 2017: 376A
View details for Web of Science ID 000394467302084
The Significance of Morphologic Dysplasia in 432 Cases of Acute Lymphoblastic Leukemia and Acute Leukemia of Ambiguous Lineage: Correlation with Cytogenetic, Immunophenotypic, and Molecular Findings
NATURE PUBLISHING GROUP. 2017: 376A
View details for Web of Science ID 000394467302085
The Significance of CD56 Expression and the RAM Immunophenotype, a Recurrent Immunophenotype Seen in Children, in Adult Acute Myeloid Leukemia
NATURE PUBLISHING GROUP. 2017: 358A–359A
View details for Web of Science ID 000394467302016
Phase I Study of Selinexor, a Selective Inhibitor of Nuclear Export, in Combination With Fludarabine and Cytarabine, in Pediatric Relapsed or Refractory Acute Leukemia
JOURNAL OF CLINICAL ONCOLOGY
2016; 34 (34): 4094-?
Purpose To characterize the toxicity, pharmacokinetics, and pharmacodynamics of selinexor, a selective inhibitor of nuclear export, when combined with fludarabine and cytarabine, in children with relapsed or refractory leukemia. Patients and Methods Eighteen patients with relapsed or refractory acute leukemia were enrolled in the SELHEM (Selinexor With Fludarabine and Cytarabine for Treatment of Refractory or Relapsed Leukemia or Myelodysplastic Syndrome) clinical trial (NCT02212561). Selinexor, initially at 30 mg/m(2) per dose, was given orally on days 1, 3, 8, 10, 22, and 24 and was escalated according to a rolling-six design. Fludarabine 30 mg/m(2) and cytarabine 2 g/m(2) were administered on days 15 to 19. Pharmacokinetic and pharmacodynamic studies were performed on days 1 and 22. Response evaluations were performed on day 15 and at the completion of course 1. Results Among the 17 patients who were evaluable for toxicity, three were treated at 30 mg/m(2), three at 40 mg/m(2), six at 55 mg/m(2), and five at 70 mg/m(2). The most common grade 3 nonhematologic toxicity was asymptomatic hyponatremia. Two patients who were treated at 70 mg/m(2) experienced reversible cerebellar toxicity, thereby defining the dose-limiting toxicity. Pharmacokinetic parameters demonstrated that plasma exposure was dose proportional. Fifteen of 16 patients demonstrated at least a twofold increase of XPO1 mRNA, indicating inhibition of the XPO1 protein. In this group of heavily pretreated, relapsed, and refractory patients, seven of 15 evaluable patients (47%) achieved complete response or complete response with incomplete count recovery. Conclusion Selinexor, in combination with fludarabine and cytarabine, is tolerable at doses up to 55 mg/m(2) in pediatric patients with relapsed or refractory leukemia. All patients who received selinexor at ≥ 40 mg/m(2) demonstrated XPO1 target inhibition. Response rates are promising and will be further explored in a phase II trial.
View details for DOI 10.1200/JCO.2016.67.5066
View details for Web of Science ID 000388929900008
View details for PubMedID 27507877
Small molecule inhibition of cAMP response element binding protein in human acute myeloid leukemia cells.
The transcription factor CREB (cAMP Response-Element Binding Protein) is overexpressed in the majority of acute myeloid leukemia (AML) patients, and this is associated with a worse prognosis. Previous work revealed that CREB overexpression augmented AML cell growth, while CREB knockdown disrupted key AML cell functions in vitro. In contrast, CREB knockdown had no effect on long-term hematopoietic stem cell activity in mouse transduction/transplantation assays. Together, these studies position CREB as a promising drug target for AML. To test this concept, a small molecule inhibitor of CREB, XX-650-23, was developed. This molecule blocks a critical interaction between CREB and its required co-activator CBP (CREB Binding Protein), leading to disruption of CREB-driven gene expression. Inhibition of CBP-CREB interaction induced apoptosis and cell-cycle arrest in AML cells, and prolonged survival in vivo in mice injected with human AML cells. XX-650-23 had little toxicity on normal human hematopoietic cells and tissues in mice. To understand the mechanism of XX-650-23, we performed RNA-seq, ChIP-seq and Cytometry Time of Flight with human AML cells. Our results demonstrate that small molecule inhibition of CBP-CREB interaction mostly affects apoptotic, cell-cycle and survival pathways, which may represent a novel approach for AML therapy.
View details for DOI 10.1038/leu.2016.139
View details for PubMedID 27211267
Replication factor C3 is a CREB target gene that regulates cell cycle progression through the modulation of chromatin loading of PCNA
2015; 29 (6): 1379-1389
CREB (cyclic AMP response element-binding protein) is a transcription factor overexpressed in normal and neoplastic myelopoiesis and regulates cell cycle progression, although its oncogenic mechanism has not been well characterized. Replication factor C3 (RFC3) is required for chromatin loading of proliferating cell nuclear antigen (PCNA) which is a sliding clamp platform for recruiting numerous proteins in the DNA metabolism. CREB1 expression, which was activated by E2F, was coupled with RFC3 expression during the G1/S progression in the KG-1 acute myeloid leukemia (AML) cell line. There was also a direct correlation between the expression of RFC3 and CREB1 in human AML cell lines as well as in the AML cells from the patients. CREB interacted directly with the CRE site in RFC3 promoter region. CREB-knockdown inhibited primarily G1/S cell cycle transition by decreasing the expression of RFC3 as well as PCNA loading onto the chromatin. Exogenous expression of RFC3 was sufficient to rescue the impaired G1/S progression and PCNA chromatin loading caused by CREB knockdown. These studies suggest that RFC3 may have a role in neoplastic myelopoiesis by promoting the G1/S progression and its expression is regulated by CREB.
View details for DOI 10.1038/leu.2014.350
View details for Web of Science ID 000355615000017
View details for PubMedID 25541153
View details for PubMedCentralID PMC4456282
Improvement in Treatment Outcome and Identification of a New Prognostic Parameter in Down Syndrome Acute Myeloid Leukemia (DS-AML): Results of the Children's Oncology Group (COG) Phase III AAML0431 Trial
AMER SOC HEMATOLOGY. 2014
View details for Web of Science ID 000349242708018
Altered resting state functional connectivity in young survivors of acute lymphoblastic leukemia.
Pediatric blood & cancer
2014; 61 (7): 1295-1299
Chemotherapy treatment for pediatric acute lymphoblastic leukemia (ALL) has been associated with long-term cognitive impairments in some patients. However, the neurobiologic mechanisms underlying these impairments, particularly in young survivors, are not well understood. This study aimed to examine intrinsic functional brain connectivity in pediatric ALL and its relationship with cognitive status.We obtained resting state functional magnetic resonance imaging (rsfMRI) and cognitive testing data from 15 ALL survivors age 8-15 years and 14 matched healthy children. The ALL group had a history of intrathecal chemotherapy treatment but were off-therapy for at least 6 months at the time of enrollment. We used seed-based analyses to compare intrinsic functional brain network connectivity between the groups. We also explored correlations between connectivity and cognitive performance, demographic, medical, and treatment variables.We demonstrated significantly reduced connectivity between bilateral hippocampus, left inferior occipital, left lingual gyrus, bilateral calcarine sulcus, and right amygdala in the ALL group compared to controls. The ALL group also showed regions of functional hyperconnectivity including right lingual gyrus, precuneus, bilateral superior occipital lobe, and right inferior occipital lobe. Functional hypoconnectivity was associated with reduced cognitive function as well as younger age at diagnosis in the ALL group.This is the first study to demonstrate that intrinsic functional brain connectivity is disrupted in pediatric ALL following chemotherapy treatment. These results help explain cognitive dysfunction even when objective test performance is seemingly normal. Children diagnosed at a younger age may show increased vulnerability to altered functional brain connectivity.
View details for DOI 10.1002/pbc.25022
View details for PubMedID 24619953
View details for PubMedCentralID PMC4028071
Development and validation of a single-cell network profiling assay-based classifier to predict response to induction therapy in paediatric patients with de novo acute myeloid leukaemia: a report from the Children's Oncology Group
BRITISH JOURNAL OF HAEMATOLOGY
2013; 162 (2): 250-262
Single cell network profiling (SCNP) is a multi-parameter flow cytometry technique for simultaneous interrogation of intracellular signalling pathways. Diagnostic paediatric acute myeloid leukaemia (AML) bone marrow samples were used to develop a classifier for response to induction therapy in 53 samples and validated in an independent set of 68 samples. The area under the curve of a receiver operating characteristic curve (AUCROC ) was calculated to be 0·85 in the training set and after exclusion of induction deaths, the AUCROC of the classifier was 0·70 (P = 0·02) and 0·67 (P = 0·04) in the validation set when induction deaths (intent to treat) were included. The highest predictive accuracy was noted in the cytogenetic intermediate risk patients (AUCROC 0·88, P = 0·002), a subgroup that lacks prognostic/predictive biomarkers for induction response. Only white blood cell count and cytogenetic risk were associated with response to induction therapy in the validation set. After controlling for these variables, the SCNP classifier score was associated with complete remission (P = 0·017), indicating that the classifier provides information independent of other clinical variables that were jointly associated with response. This is the first validation of an SCNP classifier to predict response to induction chemotherapy. Herein we demonstrate the usefulness of quantitative SCNP under modulated conditions to provide independent information on AML disease biology and induction response.
View details for DOI 10.1111/bjh.12370
View details for Web of Science ID 000321211300012
View details for PubMedID 23682827
- Prognostic features in acute megakaryoblastic leukemia in children without Down syndrome: a report from the AML02 multicenter trial and the Children's Oncology Group Study POG 9421 LEUKEMIA 2013; 27 (3): 731-734
COMPARISON OF HIGH-THROUGHPUT SEQUENCING AND FLOW CYTOMETRY FOR MEASURING MINIMAL RESIDUAL DISEASE IN PEDIATRIC ACUTE LYMPHOBLASTIC LEUKEMIA: A CHILDREN'S ONCOLOGY GROUP COHORT
SPRINGER. 2013: S23–S24
View details for Web of Science ID 000344939100056
AKT Signaling as a Novel Factor Associated with In Vitro Resistance of Human AML to Gemtuzumab Ozogamicin
2013; 8 (1)
Gemtuzumab ozogamicin (GO), an immunoconjugate between an anti-CD33 antibody and a calicheamicin-γ(1) derivative, induces remissions and improves survival in a subset of patients with acute myeloid leukemia (AML). As the mechanisms underlying GO and calicheamicin-γ(1) resistance are incompletely understood, we herein used flow cytometry-based single cell network profiling (SCNP) assays to study cellular responses of primary human AML cells to GO. Our data indicate that the extent of DNA damage is quantitatively impacted by CD33 expression and drug efflux activity. However, although DNA damage is required for GO-induced cytotoxicity, it is not sufficient for effective cell kill, suggesting that downstream anti-apoptotic pathways may function as relevant resistance mechanisms. Supporting this notion, we found activated PI3K/AKT signaling to be associated with GO resistance in vitro in primary AML cells. Consistently, the investigational AKT inhibitor MK-2206 significantly sensitized various human AML cells to GO or free calicheamicin-γ(1) with particularly pronounced effects in otherwise GO or free calicheamicin-γ(1)-resistant cells. Likewise, MK-2206 also sensitized primary AML cells to calicheamicin-γ(1). Together, our findings illustrate the capacity of SCNP assays to discover chemotherapy-related biological pathways and signaling networks relevant to GO-induced genotoxic stress. The identification of AKT signaling as being associated with GO resistance in vitro may provide a novel approach to improve the in vivo efficacy of GO/calicheamicin-γ(1) and, by extrapolation, other DNA damage-based therapeutics.
View details for DOI 10.1371/journal.pone.0053518
View details for Web of Science ID 000313429800056
View details for PubMedID 23320091
Massive evolution of the immunoglobulin heavy chain locus in children with B precursor acute lymphoblastic leukemia
2012; 120 (22): 4407-4417
The ability to distinguish clonal B-cell populations based on the sequence of their rearranged immunoglobulin heavy chain (IgH) locus is an important tool for diagnosing B-cell neoplasms and monitoring treatment response. Leukemic precursor B cells may continue to undergo recombination of the IgH gene after malignant transformation; however, the magnitude of evolution at the IgH locus is currently unknown. We used next-generation sequencing to characterize the repertoire of IgH sequences in diagnostic samples of 51 children with B precursor acute lymphoblastic leukemia (B-ALL). We identified clonal IgH rearrangements in 43 of 51 (84%) cases and found that the number of evolved IgH sequences per patient ranged dramatically from 0 to 4024. We demonstrate that the evolved IgH sequences are not the result of amplification artifacts and are unique to leukemic precursor B cells. In addition, the evolution often follows an allelic exclusion pattern, where only 1 of 2 rearranged IgH loci exhibit ongoing recombination. Thus, precursor B-cell leukemias maintain evolution at the IgH locus at levels that were previously underappreciated. This finding sheds light on the mechanisms associated with leukemic clonal evolution and may fundamentally change approaches for monitoring minimal residual disease burden.
View details for DOI 10.1182/blood-2012-05-429811
View details for Web of Science ID 000313111300023
View details for PubMedID 22932801
View details for PubMedCentralID PMC3507147
Comparison of High-Throughput Sequencing and Flow Cytometry for Measuring Minimal Residual Disease in Pediatric Acute Lymphoblastic Leukemia: A Children's Oncology Group Cohort
54th Annual Meeting and Exposition of the American-Society-of-Hematology (ASH)
AMER SOC HEMATOLOGY. 2012
View details for Web of Science ID 000313838905193
Assessing signaling pathways associated with in vitro resistance to cytotoxic agents in AML
2012; 36 (7): 900-904
This study uses single cell network profiling (SCNP) to characterize biological pathways associated with in vitro resistance or sensitivity to chemotherapeutics commonly used in acute myeloid leukemia (AML) (i.e. cytarabine/daunorubicin, gemtuzumab ozogamicin (GO), decitabine, azacitidine, clofarabine). Simultaneous measurements at the single cell level of changes in DNA damage, apoptosis and signaling pathway responses in AML blasts incubated in vitro with the above drugs showed distinct profiles for each sample and mechanistically different profiles between distinct classes of agents. Studies are ongoing to assess the clinical predictive value of these findings.
View details for DOI 10.1016/j.leukres.2012.02.022
View details for Web of Science ID 000304353400030
View details for PubMedID 22521550
Circular RNAs Are the Predominant Transcript Isoform from Hundreds of Human Genes in Diverse Cell Types
2012; 7 (2)
Most human pre-mRNAs are spliced into linear molecules that retain the exon order defined by the genomic sequence. By deep sequencing of RNA from a variety of normal and malignant human cells, we found RNA transcripts from many human genes in which the exons were arranged in a non-canonical order. Statistical estimates and biochemical assays provided strong evidence that a substantial fraction of the spliced transcripts from hundreds of genes are circular RNAs. Our results suggest that a non-canonical mode of RNA splicing, resulting in a circular RNA isoform, is a general feature of the gene expression program in human cells.
View details for DOI 10.1371/journal.pone.0030733
View details for Web of Science ID 000301977500016
View details for PubMedID 22319583
View details for PubMedCentralID PMC3270023
Next-Generation Sequencing of Immunoglobulin Heavy Chain Variable Region in Diagnostic Samples of Pediatric Acute Lymphoblastic Leukemia Identifies Hundreds of Clonal Subpopulations with Multiple Immunophenotypes
53rd Annual Meeting and Exposition of the American-Society-of-Hematology (ASH)
AMER SOC HEMATOLOGY. 2011: 624–24
View details for Web of Science ID 000299597102031
- Dorsolateral Midbrain MRI Abnormalities and Ocular Motor Deficits Following Cytarabine-Based Chemotherapy for Acute Myelogenous Leukemia JOURNAL OF NEURO-OPHTHALMOLOGY 2011; 31 (1): 52-53
A pilot study of an online cognitive rehabilitation program for executive function skills in children with cancer-related brain injury
2011; 25 (1): 101-112
Children with a history of cancer are at increased risk for cognitive impairments, particularly in executive and memory domains. Traditional, in-person cognitive rehabilitation strategies may be unavailable and/or impractical for many of these children given difficulties related to resources and health status. The feasibility and efficacy of implementing a computerized, home-based cognitive rehabilitation curriculum designed to improve executive function skills was examined in these children.A one-arm open trial pilot study of an original executive function cognitive rehabilitation curriculum was conducted with 23 paediatric cancer survivors aged 7-19.Compliance with the cognitive rehabilitation program was 83%, similar to that of many traditional programs. Following the cognitive intervention, participants showed significantly increased processing speed, cognitive flexibility, verbal and visual declarative memory scores as well as significantly increased pre-frontal cortex activation compared to baseline.These results suggest that a program of computerized cognitive exercises can be successfully implemented at home in young children with cancer. These exercises may be effective for improving executive and memory skills in this group, with concurrent changes in neurobiologic status.
View details for DOI 10.3109/02699052.2010.536194
View details for PubMedID 21142826
View details for PubMedCentralID PMC3050575
Single Cell Network Profiling (SCNP) Signatures Predict Response to Induction Therapy and Relapse Risk In Pediatric Patients with Acute Myeloid Leukemia: Children's Oncology Group (COG) Study POG-9421
AMER SOC HEMATOLOGY. 2010: 420–21
View details for Web of Science ID 000289662201057
Minimal residual disease-directed therapy for childhood acute myeloid leukaemia: results of the AML02 multicentre trial
2010; 11 (6): 543-552
We sought to improve outcome in patients with childhood acute myeloid leukaemia (AML) by applying risk-directed therapy that was based on genetic abnormalities of the leukaemic cells and measurements of minimal residual disease (MRD) done by flow cytometry during treatment.From Oct 13, 2002, to June 19, 2008, 232 patients with de-novo AML (n=206), therapy-related or myelodysplasia-related AML (n=12), or mixed-lineage leukaemia (n=14) were enrolled at eight centres. 230 patients were assigned by block, non-blinded randomisation, stratified by cytogenetic or morphological subtype, to high-dose (18 g/m(2), n=113) or low-dose (2 g/m(2), n=117) cytarabine given with daunorubicin and etoposide (ADE; induction 1). The primary aim of the study was to compare the incidence of MRD positivity of the high-dose group and the low-dose group at day 22 of induction 1. Induction 2 consisted of ADE with or without gemtuzumab ozogamicin (GO anti-CD33 monoclonal antibody); consolidation therapy included three additional courses of chemotherapy or haematopoietic stem-cell transplantation (HSCT). Levels of MRD were used to allocate GO and to determine the timing of induction 2. Both MRD and genetic abnormalities at diagnosis were used to determine the final risk classification. Low-risk patients (n=68) received five courses of chemotherapy, whereas high-risk patients (n=79), and standard-risk patients (n=69) with matched sibling donors, were eligible for HSCT (done for 48 high-risk and eight standard-risk patients). All 230 randomised patients were analysed for the primary endpoint. Other analyses were limited to the 216 patients with AML, excluding those with mixed-lineage leukaemia. This trial is closed to accrual and is registered with ClinicalTrials.gov, number NCT00136084.Complete remission was achieved in 80% (173 of 216 patients) after induction 1 and 94% (203 of 216) after induction 2. Induction failures included two deaths from toxic effects and ten cases of resistant leukaemia. The introduction of high-dose versus low-dose cytarabine did not significantly lower the rate of MRD-positivity after induction 1 (34%vs 42%, p=0.17). The 6-month cumulative incidence of grade 3 or higher infection was 79.3% (SE 4.0) for patients in the high-dose group and 75.5% (4.2) for the low-dose group. 3-year event-free survival and overall survival were 63.0% (SE 4.1) and 71.1% (3.8), respectively. 80% (155 of 193) of patients achieved MRD of less than 0.1% after induction 2, and the cumulative incidence of relapse for this group was 17% (SE 3). MRD of 1% or higher after induction 1 was the only significant independent adverse prognostic factor for both event-free (hazard ratio 2.41, 95% CI 1.36-4.26; p=0.003) and overall survival (2.11, 1.09-4.11; p=0.028).Our findings suggest that the use of targeted chemotherapy and HSCT, in the context of a comprehensive risk-stratification strategy based on genetic features and MRD findings, can improve outcome in patients with childhood AML.National Institutes of Health and American Lebanese Syrian Associated Charities (ALSAC).
View details for DOI 10.1016/S1470-2045(10)70090-5
View details for Web of Science ID 000279019500026
View details for PubMedID 20451454
Phase I Study of Valspodar (PSC-833) With Mitoxantrone and Etoposide in Refractory and Relapsed Pediatric Acute Leukemia: A Report From the Children's Oncology Group
PEDIATRIC BLOOD & CANCER
2010; 54 (5): 694-702
Valspodar, a non-immunosuppressive analog of cylosporine, is a potent P-glycoprotein (MDR1) inhibitor. As MDR1-mediated efflux of chemotherapeutic agents from leukemic blasts may contribute to drug resistance, a phase 1 study of valspodar combined with mitoxantrone and etoposide in pediatric patients with relapsed or refractory leukemias was performed.Patients received a valspodar-loading dose (2 mg/kg) followed by a 5-day continuous valspodar infusion (8, 10, 12.5, or 15 mg/kg/day) combined with lower than standard doses of mitoxantrone and etoposide. The valspodar dose was escalated using a standard 3 + 3 phase I design.Twenty-one patients were evaluable for toxicity and 20 for response. The maximum tolerated dose (MTD) of valspodar was 12.5 mg/kg/day, combined with 50% dose-reduced mitoxantrone and etoposide. The clearance of mitoxantrone and etoposide was decreased by 64% and 60%, respectively, when combined with valspodar. Dose-limiting toxicities included stomatitis, ataxia, and bone marrow aplasia. Three of 11 patients with acute lymphoblastic leukemia (ALL) had complete responses while no patient with acute myeloid leukemia (AML) had an objective response. In vitro studies demonstrated P-glycoprotein expression on the blasts of 5 of 14 patients, although only 1 had inhibition of rhodamine efflux by valspodar.While this regimen was tolerable, responses in this heavily pretreated population were limited to a subset of patients with ALL.
View details for DOI 10.1002/pbc.22366
View details for Web of Science ID 000275935700009
View details for PubMedID 20209646
View details for PubMedCentralID PMC2838930
Prevalence and prognostic significance of KIT mutations in pediatric patients with core binding factor AML enrolled on serial pediatric cooperative trials for de novo AML
2010; 115 (12): 2372-2379
KIT receptor tyrosine kinase mutations are implicated as a prognostic factor in adults with core binding factor (CBF) acute myeloid leukemia (AML). However, their prevalence and prognostic significance in pediatric CBF AML is not well established. We performed KIT mutational analysis (exon 8 and exon 17) on diagnostic specimens from 203 pediatric patients with CBF AML enrolled on 4 pediatric AML protocols. KIT mutations were detected in 38 (19%) of 203 (95% CI, 14%-25%) patient samples of which 20 (52.5%) of 38 (95% CI, 36%-69%) involved exon 8, 17 (45%) of 38 (95% CI, 29%-62%) involved exon 17, and 1 (2.5%; 95% CI, 0%-14%) involved both locations. Patients with KIT mutations had a 5-year event-free survival of 55% (+/- 17%) compared with 59% (+/- 9%) for patients with wild-type KIT (P = .86). Rates of complete remission, overall survival, disease-free survival, or relapse were not significantly different for patients with or without KIT mutations. Location of the KIT mutation and analysis by cytogenetic subtype [t(8;21) vs inv(16)] also lacked prognostic significance. Our study shows that KIT mutations lack prognostic significance in a large series of pediatric patients with CBF AML. This finding, which differs from adult series and a previously published pediatric study, may reflect variations in therapeutic approaches and/or biologic heterogeneity within CBF AML. Two of 4 studies included in this analysis are registered at http://clinicaltrials.gov as NCT00002798 (CCG-2961) and NCT00070174 (COG AAML03P1).
View details for DOI 10.1182/blood-2009-09-241075
View details for Web of Science ID 000275981900010
View details for PubMedID 20056794
WT1 Expression at Diagnosis Does Not Predict Survival in Pediatric AML: A Report From the Children's Oncology Group
PEDIATRIC BLOOD & CANCER
2009; 53 (6): 1136-1139
WT1 is a transcription factor that is aberrantly overexpressed in acute and chronic leukemias. Overexpression of WT1 in pediatric acute myeloid leukemia has been reported, but the prognostic significance is unclear because sample sizes in these studies have been relatively small. WT1 expression was measured by quantitative RT-PCR in samples obtained at diagnosis from 155 pediatric AML patients treated on a cooperative group protocol. Neither overall survival nor event-free survival was correlated with WT1 expression.
View details for DOI 10.1002/pbc.22142
View details for Web of Science ID 000270440900043
View details for PubMedID 19618455
- Speeding the Flow Toward Personalized Therapy in Childhood Acute Leukemia PEDIATRIC BLOOD & CANCER 2009; 53 (4): 525-526
Molecular inversion probes reveal patterns of 9p21 deletion and copy number aberrations in childhood leukemia
CANCER GENETICS AND CYTOGENETICS
2009; 193 (1): 9-18
Childhood leukemia, which accounts for >30% of newly diagnosed childhood malignancies, is one of the leading causes of death for children with cancer. Genome-wide studies using microarray chips to identify copy number changes in human cancer are becoming more common. In this pilot study, 45 pediatric leukemia samples were analyzed for gene copy aberrations using novel molecular inversion probe (MIP) technology. Acute leukemia subtypes included precursor B-cell acute lymphoblastic leukemia (ALL) (n=23), precursor T-cell ALL (n=6), and acute myeloid leukemia (n=14). The MIP analysis identified 69 regions of recurring copy number changes, of which 41 have not been identified with other DNA microarray platforms. Copy number gains and losses were validated in 98% of clinical karyotypes and 100% of fluorescence in situ hybridization studies available. We report unique patterns of copy number loss in samples with 9p21.3 (CDKN2A) deletion in the precursor B-cell ALL patients, compared with the precursor T-cell ALL patients. MIPs represent an attractive technology for identifying novel copy number aberrations, validating previously reported copy number changes, and translating molecular findings into clinically relevant targets for further investigation.
View details for DOI 10.1016/j.cancergencyto.2009.03.005
View details for Web of Science ID 000268922900002
View details for PubMedID 19602459
View details for PubMedCentralID PMC2776674
- Genomics of childhood leukemias: The virtue of complexity JOURNAL OF CLINICAL ONCOLOGY 2008; 26 (27): 4367-4368
Tissue microarrays from bone marrow aspirates for high-throughput assessment of immunohistologic markers in pediatric acute leukemia
PEDIATRIC AND DEVELOPMENTAL PATHOLOGY
2008; 11 (4): 283-290
Gene expression profiling studies have been employed to investigate prognostic subgroups in pediatric acute leukemia. Tissue microarrays (TMAs) are useful for high-throughput analysis of protein expression of target genes in acute leukemia samples and for validation of gene microarray analysis. Using cryopreserved samples of pediatric acute leukemia bone marrow aspirates, we constructed TMA from as few as 1 million cells. Bone marrow core biopsies from the same patients were included on the same TMA for comparison. A panel of 15 immunohistochemical markers typically used for diagnosis as well as those targeting recently characterized, prognostically relevant molecules of interest in pediatric acute leukemia was used to evaluate protein expression. Staining results confirm that suspension cells from bone marrow aspirates can be effectively used to derive protein expression data from multiple cases simultaneously with comparable efficacy to that of biopsy tissue. This method allows for new markers of diagnostic, prognostic, or therapeutic importance to be screened on large numbers of study patients. Furthermore, this technique may facilitate the inclusion of small samples, aspirates, and body fluids in large-scale studies of protein expression in clinical trials and protocols in which tissue biopsies are often unavailable.
View details for DOI 10.2350/07-04-0253.1
View details for PubMedID 17990919
- Acute leukemia in children DM DISEASE-A-MONTH 2008; 54 (4): 202-225
Molecular Inversion Probes (MIPs) identify novel areas of allelic imbalance in childhood leukemia
AMER SOC HEMATOLOGY. 2007: 431A
View details for Web of Science ID 000251100801706
The incidence and clinical significance of nucleophosmin mutations in childhood AML
2007; 110 (3): 979-985
Frameshift mutations in exon 12 of the nucleophosmin gene (NPM1) result in aberrant cytoplasmic localization of the NPM protein (NPMc(+)) and occur in 25% to 35% of adult acute myeloid leukemia (AML). In adults with AML, NPMc(+) has been associated with normal karyotype, FLT3/ITD mutations, high remission induction rates, and improved survival (particularly in patients lacking FLT3/ITD). NPMc(+) has not been well characterized in childhood AML. This study examines the incidence and clinical significance of NPMc(+) in 295 children with newly diagnosed AML treated on a large cooperative group clinical trial (POG-9421). We find that NPMc(+) is relatively uncommon in childhood AML (23 of 295 patients, 8%); and is significantly associated with FLT3/ITD mutations (P = .046), female sex (P = .029), older age (P = .047), and normal cytogenetics (P < .001). There is a favorable impact of NPMc(+) on survival in children lacking FLT3/ITD (5-year EFS, 69% vs 35%; hazard ratio, 0.39; P = .051), which is similar in magnitude to the favorable impact of t(8;21) and inv(16). We conclude that NPMc(+) is relatively rare in childhood AML, particularly in younger children. NPMc(+) does not abrogate the negative prognostic influence of FLT3/ITD mutations, but may contribute to risk stratification in children who lack FLT3/ITD mutations by identifying a group with superior prognosis.
View details for DOI 10.1182/blood-2007-02-076604
View details for Web of Science ID 000248514700035
View details for PubMedID 17440048
View details for PubMedCentralID PMC1924773
Differential gene expression patterns and interaction networks in BCR-ABL-positive and -negative adult acute lymphoblastic leukemias
JOURNAL OF CLINICAL ONCOLOGY
2007; 25 (11): 1341-1349
To identify gene expression patterns and interaction networks related to BCR-ABL status and clinical outcome in adults with acute lymphoblastic leukemia (ALL).DNA microarrays were used to profile a set of 54 adult ALL specimens from the Medical Research Council UKALL XII/Eastern Cooperative Oncology Group E2993 trial (21 p185BCR-ABL-positive, 16 p210BCR-ABL-positive and 17 BCR-ABL-negative specimens).Using supervised and unsupervised analysis tools, we detected significant transcriptomic changes in BCR-ABL-positive versus -negative specimens, and assessed their validity in an independent cohort of 128 adult ALL specimens. This set of 271 differentially expressed genes (including GAB1, CIITA, XBP1, CD83, SERPINB9, PTP4A3, NOV, LOX, CTNND1, BAALC, and RAB21) is enriched for genes involved in cell death, cellular growth and proliferation, and hematologic system development and function. Network analysis demonstrated complex interaction patterns of these genes, and identified FYN and IL15 as the hubs of the top-scoring network. Within the BCR-ABL-positive subgroups, we identified genes overexpressed (PILRB, STS-1, SPRY1) or underexpressed (TSPAN16, ADAMTSL4) in p185BCR-ABL-positive ALL relative to p210BCR-ABL-positive ALL. Finally, we constructed a gene expression- and interaction-based outcome predictor consisting of 27 genes (including GRB2, GAB1, GLI1, IRS1, RUNX2, and SPP1), which correlated with overall survival in BCR-ABL-positive adult ALL (P = .0001), independent of age (P = .25) and WBC count at presentation (P = .003).We identified prominent molecular features of BCR-ABL-positive adult ALL, which may be useful for developing novel therapeutic targets and prognostic markers in this disease.
View details for DOI 10.1200/JCO.2006.09.3534
View details for Web of Science ID 000245851900009
View details for PubMedID 17312329
Gene expression profiling predicts outcome in de novo acute myeloid leukemia (AML) with normal karyotype: Results of children's oncology group (COG) study POG #9421.
48th Annual Meeting of the American-Society-of-Hematology
AMER SOC HEMATOLOGY. 2006: 542A–542A
View details for Web of Science ID 000242440002433
Incidence and clinical significance of nucleophosmin mutations in childhood AML: A Childrens Oncology Group study.
AMER SOC HEMATOLOGY. 2006: 69A–70A
View details for Web of Science ID 000242440000222
Novel allele quantification method to classify childhood leukemia.
AMER SOC HEMATOLOGY. 2006: 643A–644A
View details for Web of Science ID 000242440003064
Differential gene expression patterns and interaction networks in BCR/ABL positive and negative adult acute lymphoblastic leukemias.
48th Annual Meeting of the American-Society-of-Hematology
AMER SOC HEMATOLOGY. 2006: 520A–520A
View details for Web of Science ID 000242440002354
- CpG island methylator phenotype and childhood leukemia CLINICAL CANCER RESEARCH 2006; 12 (16): 4787-4789
Low or absent SPARC expression in acute myeloid leukemia with MLL rearrangements is associated with sensitivity to growth inhibition by exogenous SPARC protein
2006; 20 (3): 426-432
Secreted protein, acidic and rich in cysteine (SPARC), is a matricellular glycoprotein with growth-inhibitory and antiangiogenic functions. Although SPARC has been implicated as a tumor suppressor in humans, its function in normal or malignant hematopoiesis has not previously been studied. We found that the leukemic cells of AML patients with MLL gene rearrangements express low to undetectable amounts of SPARC whereas normal hematopoietic progenitors and most AML patients express this gene. SPARC RNA and protein levels were also low or undetectable in AML cell lines with MLL translocations. Consistent with its tumor suppressive effects in various solid tumor models, exogenous SPARC protein selectively reduced the growth of cell lines with MLL rearrangements by inhibiting cell cycle progression from G1 to S phase. The lack of SPARC expression in MLL-rearranged cell lines was associated with dense promoter methylation. However, we found no evidence of methylation-based silencing of SPARC in primary patient samples. Our results suggest that low or absent SPARC expression is a consistent feature of AML cells with MLL rearrangements and that SPARC may function as a tumor suppressor in this subset of patients. A potential role of exogenous SPARC in the therapy of MLL-rearranged AML warrants further investigation.
View details for DOI 10.1038/sj.leu.2404102
View details for Web of Science ID 000235537800007
View details for PubMedID 16424866
Randomized use of cyclosporin A (CsA) to modulate P-glycoprotein in children with AML in remission: Pediatric Oncology Group Study 9421
2006; 107 (4): 1315-1324
Relapse is a major obstacle in the cure of acute myeloid leukemia (AML). The Pediatric Oncology Group AML Study 9421 tested 2 different strategies to improve event-free survival (EFS) and overall survival (OS). Patients were randomized to receive standard-dose DAT (daunorubicin, cytarabine, and thioguanine) or high-dose DAT during induction. To interfere with P-glycoprotein (P-gp)-dependent drug efflux, the second randomization tested the benefit of cyclosporine (CsA) added to consolidation chemotherapy. Of the 282 children randomly assigned to receive standard DAT induction, 248 (87.9%) achieved remission compared to 253 (91%) of the 278 receiving high-dose DAT (P = ns). Children with HLA-identical sibling donors who achieved a complete remission received an allogeneic bone marrow transplant as consolidation. For the 83 patients receiving a matched related donor bone marrow transplantation (BMT), the 3-year disease-free survival (DFS) is 67%. Of the 418 children who achieved remission and went on to consolidation with and without CsA, the DFS was 40.6% and 33.9%, respectively (P = .24). Overexpression of P-gp was infrequent (14%) in this pediatric population. In this study, intensifying induction with high-dose DAT and the addition of CsA to consolidation chemotherapy did not prolong the durations of remission or improve overall survival for children with AML.
View details for DOI 10.1128/blood-2004-08-3218
View details for Web of Science ID 000235296100018
View details for PubMedID 16254147
View details for PubMedCentralID PMC1895393
Gene expression profiling and FLT3 status correlate with outcome in de novo acute myeloid leukemia (AML) with normal karyotype: Results of children's oncology group (COG) study POG #9421.
47th Annual Meeting of the American-Society-of-Hematology
AMER SOC HEMATOLOGY. 2005: 667A–667A
View details for Web of Science ID 000233426004219
Improved remission induction rate of childhood AML: Preliminary results of the AML02 trial.
AMER SOC HEMATOLOGY. 2005: 84A
View details for Web of Science ID 000233426000276
Array CGH discovers novel genomic signatures in de novo acute myeloid leukemia (AML): Results of children's oncology group (COG) study POG #9421
AMER SOC HEMATOLOGY. 2005: 777A
View details for Web of Science ID 000233426005091
Osteonectin/SPARC is epigenetically silenced in AML with MLL gene rearrangements and selectively inhibits the growth of MLL rearranged cell lines
46th Annual Meeting of the American-Society-of-Hematology
AMER SOC HEMATOLOGY. 2004: 314A–314A
View details for Web of Science ID 000225127501108
FLT3 mutations determine the clinical outcome in children with de novo acute myelogenous leukemia (AML) and normal karyotype: Pediatric Oncology Group (POG) study # 9421.
AMER SOC HEMATOLOGY. 2004: 165A
View details for Web of Science ID 000225127500573
Gene expression profiling identifies genes associated with in vitro resistance to daunorubicin and cytarabine in children with de novo acute myelogenous leukemia (AML) from the Pediatric Oncology Group (POG) study # 9421
AMER SOC HEMATOLOGY. 2004: 320A
View details for Web of Science ID 000225127501132
Gene expression profiles at diagnosis in de novo childhood AML patients identify FLT3 mutations with good clinical outcomes
2004; 104 (9): 2646-2654
Fms-like tyrosine kinase 3 (FLT3) mutations are associated with unfavorable outcomes in children with acute myeloid leukemia (AML). We used DNA microarrays to identify gene expression profiles related to FLT3 status and outcome in childhood AML. Among 81 diagnostic specimens, 36 had FLT3 mutations (FLT3-MUs), 24 with internal tandem duplications (ITDs) and 12 with activating loop mutations (ALMs). In addition, 8 of 19 specimens from patients with relapses had FLT3-MUs. Predictive analysis of microarrays (PAM) identified genes that differentiated FLT3-ITD from FLT3-ALM and FLT3 wild-type (FLT3-WT) cases. Among the 42 specimens with FLT3-MUs, PAM identified 128 genes that correlated with clinical outcome. Event-free survival (EFS) in FLT3-MU patients with a favorable signature was 45% versus 5% for those with an unfavorable signature (P = .018). Among FLT3-MU specimens, high expression of the RUNX3 gene and low expression of the ATRX gene were associated with inferior outcome. The ratio of RUNX3 to ATRX expression was used to classify FLT3-MU cases into 3 EFS groups: 70%, 37%, and 0% for low, intermediate, and high ratios, respectively (P < .0001). Thus, gene expression profiling identified AML patients with divergent prognoses within the FLT3-MU group, and the RUNX3 to ATRX expression ratio should be a useful prognostic indicator in these patients.
View details for DOI 10.1182/blood-2004-12-4449
View details for PubMedID 15251987
Gene expression profiling (GEP) in de novo pediatric acute myeloid leukemia (AML) patients reveals a robust expression signature that correlates with inv(16) and t(16;16).
AMER SOC HEMATOLOGY. 2003: 365A
View details for Web of Science ID 000186536701324
Modulation of resistance to idarubicin by the cyclosporin PSC 833 (valspodar) in multidrug-resistant cells.
Journal of experimental therapeutics & oncology
2003; 3 (3): 127-135
Idarubicin (IDA) is an anthracycline anticancer drug utilized in the treatment of acute leukemias. There are conflicting data published with regard to the cross-resistance of IDA in multidrug-resistant (MDR) cells expressing P-glycoprotein (P-gp). We evaluated the cytotoxicity and cellular accumulation of IDA in a panel of anthracycline-selected MDR cell lines. Leukemia K562/R7 cells and sarcoma MES-SA/Dx5 cells expressing high levels of the MDR1 (ABCB1) gene were resistant to IDA (42-fold and 150-fold, respectively). In both of these cell lines, resistance to IDA was equivalent to that for doxorubicin, the drug used to select for the MDR variants. The P-gp inhibitor PSC 833 (valspodar) at 2 microM completely restored sensitivity to IDA. IDA accumulation was decreased 12-fold in MES-SA/Dx5 cells vs parental cell line, and drug uptake was restored to control levels by PSC 833. Reduced intracellular IDA was correlated with P-gp content by flow cytometry. Experiments in NIH3T3 murine cells transfected with the human MDR1 gene substantiated the findings of cross-resistance to IDA and reversal of resistance by PSC 833. Our data indicate that IDA is a high-affinity substrate for P-gp.
View details for PubMedID 14641819
Preferential expression of a mutant allele of the amplified MDR1 (ABCB1) gene in drug-resistant variants of a human sarcoma
GENES CHROMOSOMES & CANCER
2002; 34 (4): 372-383
Activation of the MDR1 (ABCB1) gene is a common event conferring multidrug resistance (MDR) in human cancers. We investigated MDR1 activation in MDR variants of a human sarcoma line, some of which express a mutant MDR1, which facilitated the study of allelic gene expression. Structural alterations of MDR1, gene copy numbers, and allelic expression were analyzed by cytogenetic karyotyping, oligonucleotide hybridization, Southern blotting, polymerase chain reaction, and DNA heteroduplex assays. Both chromosome 7 alterations and several cytogenetic changes involving the 7q21 locus are associated with the development of MDR in these sarcoma cells. Multistep-selected cells and their revertants contain three- to six-fold MDR1 gene amplification compared with that of the drug-sensitive parental cell line MES-SA and single-step doxorubicin-selected mutants. MDR1 gene amplification precedes the emergence of a mutant allele in cells that were coselected with doxorubicin and a cyclosporin inhibitor of P-glycoprotein (P-gp). Allele-specific oligonucleotide hybridization showed that the endogenous mutant allele was present as a single copy, with multiple copies of the normal allele. Reselection of revertant cells with doxorubicin in either the presence or the absence of the P-gp inhibitor resulted in exclusive reexpression of the mutant MDR1 allele, regardless of the presence of multiple wild-type MDR1 alleles. These data provide new insights into how multiple alleles are regulated in the amplicon of drug-resistant cancer cells and indicate that increased expression of an amplified gene can result from selective transcription of a single mutant allele of the gene.
View details for DOI 10.1002/gcc.10067
View details for PubMedID 12112526
Pharmacokinetic interactions of cyclosporine with etoposide and mitoxantrone in children with acute myeloid leukemia
2002; 16 (5): 920-927
The purpose of this study was to assess the effect of the multidrug resistance modulator cyclosporine (CsA) on the pharmacokinetics of etoposide and mitoxantrone in children with de novo acute myeloid leukemia (AML). Serial blood samples for pharmacokinetic studies were obtained in 38 children over a 24-h period following cytotoxin treatment with or without CsA on days 1 and 4. Drug concentrations were quantitated using validated HPLC methods, and pharmacokinetic parameters were determined using compartmental modeling with an iterative two-stage approach, implemented on ADAPT II software. Etoposide displayed a greater degree of interindividual variability in clearance and systemic exposure than mitoxantrone. With CsA treatment, etoposide and mitoxantrone mean clearance declined by 71% and 42%, respectively. These effects on clearance, in combination with the empiric 40% dose reduction for either cytotoxin, resulted in a 47% and 12% increases in the mean AUC for etoposide and mitoxantrone, respectively. There were no differences in the rates of stomatitis or infection between the two groups. CsA treatment resulted in an increased incidence of hyperbilrubinemia, which rapidly reversed upon conclusion of drug therapy. The variability observed in clearance, combined with the empiric 40% dose reduction of the cytotoxins, resulted in statistically similar systemic exposure and similar toxicity.
View details for DOI 10.1038/sj/leu/2402455
View details for Web of Science ID 000175631200020
View details for PubMedID 11986955
Mitoxantrone, etoposide, and cyclosporine therapy in pediatric patients with recurrent or refractory acute myeloid leukemia
JOURNAL OF CLINICAL ONCOLOGY
2000; 18 (9): 1867-1875
To determine the remission rate and toxicity of mitoxantrone, etoposide, and cyclosporine (MEC) therapy, multidrug resistance-1 (MDR1) status, and steady-state cyclosporine (CSA) levels in children with relapsed and/or refractory acute myeloid leukemia.MEC therapy consisted of mitoxantrone 6 mg/m(2)/d for 5 days, etoposide 60 mg/m(2)/d for 5 days, and CSA 10 mg/kg for 2 hours followed by 30 mg/kg/d as a continuous infusion for 98 hours. Because of pharmacokinetic interactions, drug doses were decreased to 60% of those found to be effective without coadministration of CSA. MDR1 expression was evaluated by reverse transcriptase polymerase chain reaction, flow cytometry, and the ability of CSA at 2.5 micromol/L to increase intracellular accumulation of (3)H-daunomycin in blasts from bone marrow specimens.The remission rate was 35% (n = 23 of 66). Overall, 35% of patients (n = 23) achieved complete remission (CR), 12% of patients (n = 8) achieved partial remission, and 9% of patients (n = 6) died of infection. Exposure to CSA levels of greater than 2,400 ng/mL was achieved in 95% of patients (n = 56 of 59). Toxicities included infection, cardiotoxicity, myelosuppression, stomatitis, and reversible increases in serum creatinine and bilirubin. In most who had relapsed while receiving therapy or whose induction therapy had failed, response was not significantly different for MDR1-positive and MDR1-negative patients.Serum levels of CSA capable of reversing multidrug resistance are achievable in children with acceptable toxicity. The CR rate of 35% achieved in this study is comparable to previously reported results using standard doses of mitoxantrone and etoposide. The use of CSA may have improved the response rate for the MDR1-positive patients so that it was not different from that for the MDR1-negative patients.
View details for Web of Science ID 000086873900008
View details for PubMedID 10784627
Loss of cyclosporin and azidopine binding are associated with altered ATPase activity by a mutant p-glycoprotein with deleted Phe(335)
2000; 57 (4): 769-777
In this study, we further characterize a mutant P-glycoprotein (P-gp) that has a deletion of Phe(335) and is resistant to inhibition by cyclosporins. Photoaffinity labeling with [(3)H]cyclosporine and [(3)H]azidopine revealed markedly decreased binding to the mutant P-gp compared with wild-type P-gp. Expression of the mutant P-gp in multidrug-resistant variant cell line MES-SA/DxP (DxP) cells was associated with a 2-fold higher basal ATPase activity relative to multidrug-resistant cell line MES-SA/Dx5 (Dx5) cells with wild-type P-gp. Cyclosporine inhibited ATPase activity in both cell types, whereas the cyclosporin D analog valspodar (PSC 833), vinblastine, and dactinomycin stimulated ATPase activity in Dx5 but not in mutant DxP cells. Moreover, the cell lines differed in their responses to verapamil, which produced greater stimulation of ATPase in Dx5 than DxP cells. Verapamil significantly reversed the [(3)H]daunorubicin accumulation defect in wild-type Dx5 cells, but it had no significant effect on [(3)H]daunorubicin accumulation in the mutant DxP cells. Verapamil was not transported by cells expressing either mutant or wild-type P-gp. Vanadate trapping of azido-ATP was markedly impaired in mutant P-gp. In conclusion, our data demonstrate that Phe(335) of transmembrane 6 is an important amino acid residue for the formation of cyclosporine and azidopine drug-binding site(s). Phe(335) also plays a role in the coupling of verapamil binding and modulation of daunorubicin intracellular accumulation in wild-type P-gp. In addition, Phe(335) in transmembrane 6 may play a role in coupling drug binding to ATPase activity. The deletion of Phe(335) results in a significant increase in the basal ATPase activity with a concomitant decrease in its ability to trap ATP and transport some P-gp substrates.
View details for Web of Science ID 000086066500017
View details for PubMedID 10727524
Multidrug-resistant human sarcoma cells with a mutant P-glycoprotein, altered phenotype, and resistance to cyclosporins
JOURNAL OF BIOLOGICAL CHEMISTRY
1997; 272 (9): 5974-5982
A variant of the multidrug-resistant human sarcoma cell line Dx5 was derived by co-selection with doxorubicin and the cyclosporin D analogue PSC 833, a potent inhibitor of the multidrug transporter P-glycoprotein. The variant DxP cells manifest an altered phenotype compared with Dx5, with decreased cross-resistance to Vinca alkaloids and no resistance to dactinomycin. Resistance to doxorubicin and paclitaxel is retained. The multidrug resistance phenotype of DxP cells is not modulated by 2 microM PSC 833 or cyclosporine. DxP cells manifest a decreased ability to transport [3H]cyclosporine. DNA heteroduplex analysis and sequencing reveal a mutant mdr1 gene (deletion of a phenylalanine at amino acid residue 335) in the DxP cell line. The mutant P-glycoprotein has a decreased affinity for PSC 833 and vinblastine and a decreased ability to transport rhodamine 123. Transfection of the mutant mdr1 gene into drug-sensitive MES-SA sarcoma cells confers resistance to both doxorubicin and PSC 833. Our study demonstrates that survival of cells exposed to doxorubicin and PSC 833 in a multistep selection occurred as a result of a P-glycoprotein mutation in transmembrane region 6. These data suggest that Phe335 is an important binding site on P-glycoprotein for substrates such as dactinomycin and vinblastine and for inhibitors such as cyclosporine and PSC 833.
View details for Web of Science ID A1997WK74700086
View details for PubMedID 9038218