Sneha Ramakrishna obtained her B. A. from the University of Chicago and her M.D. from the Cleveland Clinic Lerner College of Medicine at Case Western Reserve University. In medical school, through the Howard Hughes Medical Research Scholar Award, she joined Dr. Crystal Mackall’s laboratory, where she designed and developed various GD2 CAR-Ts and tested them in preclinical models. During her residency training in Pediatrics at the Children’s Hospital of Philadelphia, she cared for some of the first patients treated with CD19 CAR T cells, learning the power of this therapy first-hand. During her fellowship in Pediatric Hematology/Oncology at the Johns Hopkins/National Cancer Institute combined program, she worked with Dr. Terry Fry. She evaluated the mechanism of CD22 CAR T cell relapse in patients by developing an antigen escape model and establishing a deeper understanding of the effects of antigen density on CAR-T phenotype, expansion, and persistence (Fry…Ramakrishna…Mackall Nat Med, 2018; Ramakrishna, et al., Clinical Cancer Research, 2019). Since arriving at Stanford, Dr. Ramakrishna leads an interdisciplinary team that designs, develops, and successfully implements a robust correlative science platform for our novel CAR-T therapies. Analyzing patient samples from our first-in-human GD2 CAR-T trial (NCT04196413) treating a universally fatal cancer, diffuse midline glioma (DMG), we identified that intracerebroventricular CAR-T administration correlates with enhanced pro-inflammatory cytokines and reduced immunosuppressive cell populations in cerebrospinal fluid as compared to intravenous CAR-T administration (Majzner*, Ramakrishna*, et al., Nature 2022 *co-first authors). Her research program evaluates unique sets of patient samples using novel single-cell immune profiling to identify the drivers of CAR-T success or failure. Building on these findings, her team will assess approaches to enhance CAR-T efficacy and translate these findings to the clinic.
Clinically, Dr. Ramakrishna cares for children with solid tumors and treats hematologic, solid, and brain tumor pediatric patients with CAR T cell therapies in the Cancer Cellular Therapies program.
- Pediatric Hematology-Oncology
Honors & Awards
Clinical Scientist Research Career Development Award (K08), National Cancer Institute (2022-2027)
Young Investigator Award, Hyundai Hope on Wheels (2020-2022)
ASH Abstract Achievement Award, American Society of Hematology (2017)
Research Scholar, Howard Hughes Medical Institute (2010)
Board Certification: American Board of Pediatrics, Pediatric Hematology-Oncology (2019)
Board Certification, American Board of Pediatrics, Hematology/Oncology (2019)
Board Certification: American Board of Pediatrics, Pediatrics (2015)
Fellowship: Johns Hopkins and National Cancer Institute Ped Hematology and Oncology Training (2018) MD
Residency: Children's Hospital of Philadelphia Pediatric Residency (2015) PA
Medical Education: Case Western Reserve School of Medicine (2012) OH
Additional Clinical Info
GD2 CAR T Cells in Diffuse Intrinsic Pontine Gliomas(DIPG) & Spinal Diffuse Midline Glioma(DMG)
The primary purpose of this study is to test whether GD2-CAR T cells can be successfully made from immune cells collected from children and young adults with H3K27M-mutant diffuse intrinsic pontine glioma (DIPG) or spinal H3K27M-mutant diffuse midline glioma (DMG). H3K27Mmutant testing will occur as part of standard of care prior to enrollment.
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.
CD22-CAR T Cells in Children and Young Adults With B Cell Malignancies
The primary purpose of this study is to test whether CD22-CAR T cells can be successfully made from immune cells collected from pediatric and young adult subjects with relapsed/refractory B-cell malignancies (leukemia and lymphoma). Another purpose of this study is to test the safety and cancer killing ability of a cell therapy against a new cancer target (CD22).
Stanford is currently not accepting patients for this trial. For more information, please contact Michael C Kunicki, 650-736-0555.
SPEARHEAD-3 Pediatric Study
This is a pediatric basket study to investigate the safety and efficacy of afamitresgene autoleucel in HLA-A*02 eligible and MAGE-A4 positive subjects aged 2-21 years of age with advanced cancers
Stanford is currently not accepting patients for this trial.
Immune determinants of CAR-T cell expansion in solid tumor patients receiving GD2 CAR-T cell therapy.
Chimeric antigen receptor T cells (CAR-Ts) have remarkable efficacy in liquid tumors, but limited responses in solid tumors. We conducted a Phase I trial (NCT02107963) of GD2 CAR-Ts (GD2-CAR.OX40.28.z.iC9), demonstrating feasibility and safety of administration in children and young adults with osteosarcoma and neuroblastoma. Since CAR-T efficacy requires adequate CAR-T expansion, patients were grouped into good or poor expanders across dose levels. Patient samples were evaluated by multi-dimensional proteomic, transcriptomic, and epigenetic analyses. T cell assessments identified naive T cells in pre-treatment apheresis associated with good expansion, and exhausted T cells in CAR-T products with poor expansion. Myeloid cell assessment identified CXCR3+ monocytes in pre-treatment apheresis associated with good expansion. Longitudinal analysis of post-treatment samples identified increased CXCR3- classical monocytes in all groups as CAR-T numbers waned. Together, our data uncover mediators of CAR-T biology and correlates of expansion that could be utilized to advance immunotherapies for solid tumor patients.
View details for DOI 10.1016/j.ccell.2023.11.011
View details for PubMedID 38134936
INSPIRED Symposium Part 4B: CAR T cell correlative studies-established findings and future priorities.
Transplantation and cellular therapy
Chimeric antigen receptor (CAR) T cells have revolutionized the treatment of B cell malignancies, with multiple CAR T cell products having received approval by regulatory agencies around the world for numerous indications. However, significant work remains to be done to enhance these treatments. In March 2023, a group of experts in CAR T cell therapy assembled at the National Institutes of Health in Bethesda, MD, USA at the Insights in Pediatric CAR T-cell Immunotherapy: Recent Advances and Future Directions (INSPIRED) Symposium to identify key areas for research for the coming years. In session 4B, correlative studies to be incorporated into future clinical trials and real-world settings were discussed. Active areas of research identified included: 1) optimization of CAR T cell product manufacturing; 2) ensuring adequate lymphodepletion prior to CAR T cell administration; 3) overcoming immunoregulatory cells and tumor stroma present in the tumor microenvironment, particularly in solid tumors; 4) understanding tumor intrinsic properties that lead to CAR T cell immunotherapy resistance; and 5) uncovering biomarkers predictive of treatment resistance, treatment durability or immune-related adverse events. Here we review the results of previously published clinical trials and real-world studies to outline what is currently understood on each of these topics. We then outline priorities for future research that we believe will be important for improving our understanding of CAR T cell therapy and ultimately leading to better outcomes for patients.
View details for DOI 10.1016/j.jtct.2023.10.012
View details for PubMedID 37863355
GD2-CAR T cell therapy for H3K27M-mutated diffuse midline gliomas.
Diffuse intrinsic pontine glioma (DIPG) and other H3K27M-mutated diffuse midline gliomas (DMG) are universally lethal paediatric central nervous system tumours1. We previously discovered that the disialoganglioside GD2 is highly expressed on H3K27M-mutant glioma cells and demonstrated promising preclinical efficacy of GD2-directed chimeric antigen receptor (CAR) T cells2, providing the rationale for a first-in-human Phase 1 clinical trial (NCT04196413). Because CAR T-cell-induced brainstem inflammation can result in obstructive hydrocephalus, increased intracranial pressure, and dangerous tissue shifts, neurocritical care precautions were incorporated. Here we present the clinical experience from the first four patients with H3K27M-mutant DIPG/DMG treated with GD2-CAR T cells (GD2-CART) at dose level 1 (1e6 GD2-CAR T cells/kg administered intravenously). Patients who exhibited clinical benefit were eligible for subsequent GD2-CAR T infusions administered intracerebroventricularly3. Toxicity was largely related to tumor location and reversible with intensive supportive care. On-target, off-tumor toxicity was not observed. Three of four patients exhibited clinical and radiographic improvement. Proinflammatory cytokines were increased in plasma and cerebrospinal fluid (CSF). Transcriptomic analyses of 65,598 single cells from CAR T cell products and CSF elucidate heterogeneity in response between subjects and administration routes. These early results underscore the promise of this approach for H3K27M+ DIPG/DMG therapy.
View details for DOI 10.1038/s41586-022-04489-4
View details for PubMedID 35130560
Modulation of Target Antigen Density Improves CAR T Cell Functionality and Persistence.
Clinical cancer research : an official journal of the American Association for Cancer Research
Chimeric antigen receptor T cell (CART) therapy targeting CD22 induces remission in 70% of patients with relapsed/refractory acute lymphoblastic leukemia (ALL). However, the majority of post-CD22 CART remissions are short and associated with reduction in CD22 expression. We evaluate the implications of low antigen density on the activity of CD22 CART and propose mechanisms to overcome antigen escape.Using ALL cell lines with variable CD22 expression, we evaluate the cytokine profile, cytotoxicity, and in vivo CART functionality in the setting of low CD22 expression. We develop a high-affinity CD22 CAR as an approach to improve CAR sensitivity. We also assess Bryostatin1, a therapeutically relevant agent, to upregulate CD22 and improve CAR functionality.We demonstrate that low CD22 expression negatively impacts in vitro and in vivo CD22 CART functionality and impairs in vivo CART persistence. Moreover, low antigen expression on leukemic cells increases naïve phenotype of persisting CART. Increasing CAR affinity does not improve response to low-antigen leukemia. Bryostatin1 upregulates CD22 on leukemia and lymphoma cell lines for 1 week following single-dose exposure, improves CART functionality and in vivo persistence. While Bryostatin1 attenuates IFN-gamma production by CART, overall in vitro and in vivo CART cytotoxicity is not adversely affected. Finally, administration of Bryostain1 with CD22 CAR results in longer duration of in vivo response.We demonstrate that target antigen modulation is a promising strategy to improve CD22 CAR efficacy and remission durability in patients with leukemia and lymphoma.
View details for DOI 10.1158/1078-0432.CCR-18-3784
View details for PubMedID 31110075
Tumor inflammation-associated neurotoxicity.
Cancer immunotherapies have unique toxicities. Establishment of grading scales and standardized grade-based treatment algorithms for toxicity syndromes can improve the safety of these treatments, as observed for cytokine release syndrome (CRS) and immune effector cell associated neurotoxicity syndrome (ICANS) in patients with B cell malignancies treated with chimeric antigen receptor (CAR) T cell therapy. We have observed a toxicity syndrome, distinct from CRS and ICANS, in patients treated with cell therapies for tumors in the central nervous system (CNS), which we term tumor inflammation-associated neurotoxicity (TIAN). Encompassing the concept of 'pseudoprogression,' but broader than inflammation-induced edema alone, TIAN is relevant not only to cellular therapies, but also to other immunotherapies for CNS tumors. To facilitate the safe administration of cell therapies for patients with CNS tumors, we define TIAN, propose a toxicity grading scale for TIAN syndrome and discuss the potential management of this entity, with the goal of standardizing both reporting and management.
View details for DOI 10.1038/s41591-023-02276-w
View details for PubMedID 37024595
View details for PubMedCentralID 7238960
Role of peripheral blood MRD and 18F-FDG PET in the post-CAR relapse setting: a case study of discordant peripheral blood and bone marrow MRD.
Journal for immunotherapy of cancer
2023; 11 (2)
Chimeric antigen receptor (CAR) T cell therapy is an effective salvage therapy for pediatric relapsed B-cell acute lymphoblastic leukemia (B-ALL), yet is challenged by high rates of post-CAR relapse. Literature describing specific relapse patterns and extramedullary (EM) sites of involvement in the post-CAR setting remains limited, and a clinical standard for post-CAR disease surveillance has yet to be established. We highlight the importance of integrating peripheral blood minimal residual disease (MRD) testing and radiologic imaging into surveillance strategies, to effectively characterize and capture post-CAR relapse.Here, we describe the case of a child with multiply relapsed B-ALL who relapsed in the post-CAR setting with gross non-contiguous medullary and EM disease. Interestingly, her relapse was identified first from peripheral blood flow cytometry MRD surveillance, in context of a negative bone marrow aspirate (MRD <0.01%). Positron emission tomography with 18F-fluorodeoxyglucose revealed diffuse leukemia with innumerable bone and lymph node lesions, interestingly sparing her sacrum, the site of her bone marrow aspirate sampling.We highlight this case as both peripheral blood MRD and 18F-fluorodeoxyglucose positron emission tomography imaging were more sensitive than standard bone marrow aspirate testing in detecting this patient's post-CAR relapse. Clinical/Biologic Insight: In the multiply relapsed B-ALL setting, where relapse patterns may include patchy medullary and/or EM disease, peripheral blood MRD and/or whole body imaging, may carry increased sensitivity at detecting relapse in patient subsets, as compared with standard bone marrow sampling.
View details for DOI 10.1136/jitc-2022-004851
View details for PubMedID 36849202
View details for PubMedCentralID PMC9972424
- CD22-CAR T-Cell Therapy Mediates High Durable Remission Rates in Adults with Large B-Cell Lymphoma Who Have Relapsed after CD19-CAR T-Cell Therapy AMER SOC HEMATOLOGY. 2021
CAR T cells with dual targeting of CD19 and CD22 in adult patients with recurrent or refractory B cell malignancies: a phase 1 trial.
Despite impressive progress, more than 50% of patients treated with CD19-targeting chimeric antigen receptor T cells (CAR19) experience progressive disease. Ten of 16 patients with large B cell lymphoma (LBCL) with progressive disease after CAR19 treatment had absent or low CD19. Lower surface CD19 density pretreatment was associated with progressive disease. To prevent relapse with CD19- or CD19lo disease, we tested a bispecific CAR targeting CD19 and/or CD22 (CD19-22.BB.z-CAR) in a phase I clinical trial ( NCT03233854 ) of adults with relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL) and LBCL. The primary end points were manufacturing feasibility and safety with a secondary efficacy end point. Primary end points were met; 97% of products met protocol-specified dose and no dose-limiting toxicities occurred during dose escalation. In B-ALL (n=17), 100% of patients responded with 88% minimal residual disease-negative complete remission (CR); in LBCL (n=21), 62% of patients responded with 29% CR. Relapses were CD19-/lo in 50% (5 out of 10) of patients with B-ALL and 29% (4 out of 14) of patients with LBCL but were not associated with CD22-/lo disease. CD19/22-CAR products demonstrated reduced cytokine production when stimulated with CD22 versus CD19. Our results further implicate antigen loss as a major cause of CAR T cell resistance, highlight the challenge of engineering multi-specific CAR T cells with equivalent potency across targets and identify cytokine production as an important quality indicator for CAR T cell potency.
View details for DOI 10.1038/s41591-021-01436-0
View details for PubMedID 34312556
Use of cardiac radiation therapy as bridging therapy to CAR-T for relapsed pediatric B-cell acute lymphoblastic leukemia.
Pediatric blood & cancer
The use of radiotherapy as bridging therapy to chimeric antigen receptor T-cell therapy (CAR-T) in pre-B acute lymphoblastic leukemia (B-ALL) has been minimally explored. Here, we present a boy with B-ALL who relapsed after allogeneic bone marrow transplant with disseminated disease, including significant symptomatic cardiovascular and gastrointestinal (GI) involvement. The cardiac and GI leukemic infiltrates were successfully treated with bridging radiation therapy (BRT) prior to CAR-T infusion. Using this approach, he successfully tolerated CAR-T with no evidence of disease or sequelae on 3-month follow-up. This is the first reported case of safe and effective delivery of cardiac BRT in B-ALL.
View details for DOI 10.1002/pbc.28870
View details for PubMedID 33355997
- Using single-cell analysis to predict CAR T cell outcomes. Nature medicine 2020
- Use of Chimeric Antigen Receptor Modified T Cells With Extensive Leukemic Myocardial Involvement JACC: CARDIOONCOLOGY 2020; 2 (4): 666–70
Identification of dual positive CD19+/CD3+ T cells in a leukapheresis product undergoing CAR transduction: a case report.
Journal for immunotherapy of cancer
2020; 8 (2)
BACKGROUND: Chimeric antigen receptor (CAR) therapy and hematopoietic stem cell transplantation (HSCT) are therapeutics for relapsed acute lymphocytic leukemia (ALL) that are increasingly being used in tandem. We identified a non-physiologic CD19+/CD3+ T-cell population in the leukapheresis product of a patient undergoing CAR T-cell manufacturing who previously received a haploidentical HSCT, followed by infusion of a genetically engineered T-cell addback product. We confirm and report the origin of these CD19+/CD3+ T cells that have not previously been described in context of CAR T-cell manufacturing. We additionally interrogate the fate of these CD19-expressing cells as they undergo transduction to express CD19-specific CARs.MAIN BODY: We describe the case of a preteen male with multiply relapsed B-ALL who was treated with sequential cellular therapies. He received an alphabeta T-cell depleted haploidentical HSCT followed by addback of donor-derived T cells genetically modified with a suicide gene for iCaspase9 and truncated CD19 for cell tracking (RivoCel). He relapsed 6months following HSCT and underwent leukapheresis and CAR T-cell manufacturing. During manufacturing, we identified an aberrant T-cell population dually expressing CD19 and CD3. We hypothesized that these cells were RivoCel cells and confirmed using flow cytometry and PCR that the identified cells were in fact RivoCel cells and were eliminated with iCaspase9 activation. We additionally tracked these cells through CD19-specific CAR transduction and notably did not detect T cells dually positive for CD19 and CD19-directed CARs. The most likely rationale for this is in vitro fratricide of the CD19+ 'artificial' T-cell population by the CD19-specific CAR+ T cells in culture.CONCLUSIONS: We report the identification of CD19+/CD3+ cells in an apheresis product undergoing CAR transduction derived from a patient previously treated with a haploidentical transplant followed by RivoCel addback. We aim to bring attention to this cell phenotype that may be recognized with greater frequency as CAR therapy and engineered alphabetahaplo-HSCT are increasingly coupled. We additionally suggest consideration towards using alternative markers to CD19 as a synthetic identifier for post-transplant addback products, as CD19-expression on effector T cells may complicate subsequent treatment using CD19-directed therapy.
View details for DOI 10.1136/jitc-2020-001073
View details for PubMedID 32929049
- Delayed cancer diagnoses and high mortality in children during the COVID-19 pandemic. Pediatric blood & cancer 2020: e28427
Prospects and Challenges for Use of CAR T Cell Therapies in Solid Tumors.
Expert opinion on biological therapy
Introduction: Chimeric antigen receptor (CAR) T cell therapy has provided patients with relapsed/refractory B cell malignancies with a new therapeutic option, but this class of therapeutics has not demonstrated consistent therapeutic benefit in solid tumors.Areas Covered: Here we review the literature to identify numerous factors that contribute to this discrepancy, using pediatric cancers as a platform to understand these limitations. We discuss an inability to target highly and homogenously expressed lineage-associated antigens due to risks of on-target, off-tumor toxicity, T cell dysfunction related to T cell exhaustion and the suppressive tumor microenvironment (TME), and inefficient CAR T cell trafficking into solid tumors. As our understanding of the biology of CAR T cells improves and innovations in engineering CAR platforms emerge, next generation CAR T cell therapeutics designed to overcome these challenges will enter the clinic for testing.Expert Opinion: New approaches to address the challenges that have limited the efficacy of CAR T cell therapeutics in solid tumors are emerging. These include next-generation CAR T cell engineering to overcome antigen heterogeneity, to mitigate T cell exhaustion and to prevent suppression by the TME, and novel approaches for regional delivery to overcome limitations in tumor T cell trafficking.
View details for DOI 10.1080/14712598.2020.1738378
View details for PubMedID 32125191
Immunotherapy for the Treatment of Acute Lymphoblastic Leukemia.
Current oncology reports
2020; 22 (2): 11
PURPOSE OF REVIEW: Immunotherapy for the treatment of acute lymphoblastic leukemia (ALL) broadens therapeutic options beyond chemotherapy and targeted therapy. Here, we review the use of monoclonal antibody-based drugs and cellular therapies to treat ALL. We discuss the challenges facing the field regarding the optimal timing and sequencing of these therapies in relation to other treatment options as well as considerations of cost effectiveness.RECENT FINDINGS: By early identification of patients at risk for leukemic relapse, monoclonal antibody and cellular immunotherapies can be brought to the forefront of treatment options. Novel CAR design and manufacturing approaches may enhance durable patient response. Multiple clinical trials are now underway to evaluate the sequence and timing of monoclonal antibody, cellular therapy, and/or stem cell transplantation. The biologic and clinical contexts in which immunotherapies have advanced the treatment of ALL confer optimism that more patients will achieve durable remissions. Immunotherapy treatments in ALL will expand through rationally targeted approaches alongside advances in CAR T cell therapy design and clinical experience.
View details for DOI 10.1007/s11912-020-0875-2
View details for PubMedID 31997022
CD22-Directed CAR T-Cell Therapy Induces Complete Remissions in CD19-Directed CAR-Refractory Large B-Cell Lymphoma.
The prognosis for patients with large B-cell lymphoma (LBCL) progressing after treatment with chimeric antigen receptor (CAR) T-cell therapy targeting CD19 (CAR19) is poor. We report on the first three consecutive patients with autologous CAR19-refractory LBCL treated with a single infusion of autologous 1×106 CAR+ T-cells/kg targeting CD22 (CAR22) as part of a phase I dose escalation study. CAR22 therapy was relatively well tolerated, without any observed non-hematologic adverse events higher than grade 2. Following infusion, all three patients achieved complete remission, with all responses ongoing at the time of last follow up (mean 7.8 months, range 6-9.3). Circulating CAR22 cells demonstrated robust expansion (peak range 85.4-350 cells/µL), and persisted beyond three months in all patients with continued radiographic responses and corresponding decreases in circulating tumor DNA (ctDNA) beyond six months post-infusion. Further accrual at a higher dose level in this phase 1 dose-escalation study is ongoing and will explore the role of this therapy in patients who have failed prior CAR T-cell therapies. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT04088890).
View details for DOI 10.1182/blood.2020009432
View details for PubMedID 33512414
- Supercharging your CAR. Blood 2020; 135 (9): 593–94
Preclinical Development of Bivalent Chimeric Antigen Receptors Targeting Both CD19 and CD22
2018; 11: 127–37
Despite high remission rates following CAR-T cell therapy in B-ALL, relapse due to loss of the targeted antigen is increasingly recognized as a mechanism of immune escape. We hypothesized that simultaneous targeting of CD19 and CD22 may reduce the likelihood of antigen loss, thus improving sustained remission rates. A systematic approach to the generation of CAR constructs incorporating two target-binding domains led to several novel CD19/CD22 bivalent CAR constructs. Importantly, we demonstrate the challenges associated with the construction of a bivalent CAR format that preserves bifunctionality against both CD19 and CD22. Using the most active bivalent CAR constructs, we found similar transduction efficiency compared to that of either CD19 or CD22 single CARs alone. When expressed on human T cells, the optimized CD19/CD22 CAR construct induced comparable interferon γ and interleukin-2 in vitro compared to single CARs against dual-antigen-expressing as well as single-antigen-expressing cell lines. Finally, the T cells expressing CD19/CD22 CAR eradicated ALL cell line xenografts and patient-derived xenografts (PDX), including a PDX generated from a patient with CD19- relapse following CD19-directed CAR therapy. The CD19/CD22 bivalent CAR provides an opportunity to test whether simultaneous targeting may reduce risk of antigen loss.
View details for DOI 10.1016/j.omto.2018.10.006
View details for Web of Science ID 000454075900012
View details for PubMedID 30581986
View details for PubMedCentralID PMC6300726
CD22-targeted CAR T cells induce remission in B-ALL that is naive or resistant to CD19-targeted CAR immunotherapy.
Chimeric antigen receptor (CAR) T cells targeting CD19 mediate potent effects in relapsed and/or refractory pre-B cell acute lymphoblastic leukemia (B-ALL), but antigen loss is a frequent cause of resistance to CD19-targeted immunotherapy. CD22 is also expressed in most cases of B-ALL and is usually retained following CD19 loss. We report results from a phase 1 trial testing a new CD22-targeted CAR (CD22-CAR) in 21 children and adults, including 17 who were previously treated with CD19-directed immunotherapy. Dose-dependent antileukemic activity was observed, with complete remission obtained in 73% (11/15) of patients receiving ≥1 × 106 CD22-CAR T cells per kg body weight, including 5 of 5 patients with CD19dim or CD19- B-ALL. Median remission duration was 6 months. Relapses were associated with diminished CD22 site density that likely permitted CD22+ cell escape from killing by CD22-CAR T cells. These results are the first to establish the clinical activity of a CD22-CAR in B-ALL, including leukemia resistant to anti-CD19 immunotherapy, demonstrating potency against B-ALL comparable to that of CD19-CAR at biologically active doses. Our results also highlight the critical role played by antigen density in regulating CAR function.
View details for PubMedID 29155426
Reduction of MDSCs with All-trans Retinoic Acid Improves CAR Therapy Efficacy for Sarcomas
CANCER IMMUNOLOGY RESEARCH
2016; 4 (10): 869-880
Genetically engineered T cells expressing CD19-specific chimeric antigen receptors (CAR) have shown impressive activity against B-cell malignancies, and preliminary results suggest that T cells expressing a first-generation disialoganglioside (GD2)-specific CAR can also provide clinical benefit in patients with neuroblastoma. We sought to assess the potential of GD2-CAR therapies to treat pediatric sarcomas. We observed that 18 of 18 (100%) of osteosarcomas, 2 of 15 (13%) of rhabdomyosarcomas, and 7 of 35 (20%) of Ewing sarcomas expressed GD2. T cells engineered to express a third-generation GD2-CAR incorporating the 14g2a-scFv with the CD28, OX40, and CD3ζ signaling domains (14g2a.CD28.OX40.ζ) mediated efficient and comparable lysis of both GD2(+) sarcoma and neuroblastoma cell lines in vitro However, in xenograft models, GD2-CAR T cells had no antitumor effect against GD2(+) sarcoma, despite effectively controlling GD2(+) neuroblastoma. We observed that pediatric sarcoma xenografts, but not neuroblastoma xenografts, induced large populations of monocytic and granulocytic murine myeloid-derived suppressor cells (MDSC) that inhibited human CAR T-cell responses in vitro Treatment of sarcoma-bearing mice with all-trans retinoic acid (ATRA) largely eradicated monocytic MDSCs and diminished the suppressive capacity of granulocytic MDSCs. Combined therapy using GD2-CAR T cells plus ATRA significantly improved antitumor efficacy against sarcoma xenografts. We conclude that retinoids provide a clinically accessible class of agents capable of diminishing the suppressive effects of MDSCs, and that co-administration of retinoids may enhance the efficacy of CAR therapies targeting solid tumors. Cancer Immunol Res; 4(10); 869-80. ©2016 AACR.
View details for DOI 10.1158/2326-6066.CIR-15-0230
View details for Web of Science ID 000385632900007
View details for PubMedID 27549124
View details for PubMedCentralID PMC5050151