Search

Chimeric antigen receptor (CAR) T cells have induced remarkable antitumor responses in B cell malignancies. Some patients do not respond because of T cell deficiencies that hamper the expansion, persistence, and effector function of these cells. We used longitudinal immune profiling to identify phenotypic and pharmacodynamic changes in CD19-directed CAR T cells in patients with chronic lymphocytic leukemia (CLL). CAR expression maintenance was also investigated because this can affect response durability. CAR T cell failure was accompanied by preexisting T cell-intrinsic defects or dysfunction acquired after infusion. In a small subset of patients, CAR silencing was observed coincident with leukemia relapse. Using a small molecule inhibitor, we demonstrated that the bromodomain and extra-terminal (BET) family of chromatin adapters plays a role in downregulating CAR expression. BET protein blockade also ameliorated CAR T cell exhaustion as manifested by inhibitory receptor reduction, enhanced metabolic fitness, increased proliferative capacity, and enriched transcriptomic signatures of T cell reinvigoration. BET inhibition decreased levels of the TET2 methylcytosine dioxygenase, and forced expression of the TET2 catalytic domain eliminated the potency-enhancing effects of BET protein targeting in CAR T cells, providing a mechanism linking BET proteins and T cell dysfunction. Thus, modulating BET epigenetic readers may improve the efficacy of cell-based immunotherapies.

The SARS-CoV-2 coronavirus (COVID-19) pandemic has significantly impacted the delivery of cellular therapeutics, including chimeric antigen receptor (CAR) T cells. This impact has extended beyond patient care to include logistics, administration, and distribution of increasingly limited health care resources. Based on the collective experience of the CAR T-cell Consortium investigators, we review and address several questions and concerns regarding cellular therapy administration in the setting of COVID-19 and make general recommendations to address these issues. Specifically, we address (1) necessary resources for safe administration of cell therapies; (2) determinants of cell therapy utilization; (3) selection among patients with B cell non-Hodgkin lymphomas and B cell acute lymphoblastic leukemia; (4) supportive measures during cell therapy administration; (5) use and prioritization of tocilizumab; and (6) collaborative care with referring physicians. These recommendations were carefully formulated with the understanding that resource allocation is of the utmost importance, and that the decision to proceed with CAR T cell therapy will require extensive discussion of potential risks and benefits. Although these recommendations are fluid, at this time it is our opinion that the COVID-19 pandemic should not serve as reason to defer CAR T cell therapy for patients truly in need of a potentially curative therapy., Competing Interests: Conflict of interest statement V.B. has received research funding from Novartis, Celgene, Incyte, Gamida Cell, and GT Biopharma and serves on advisory boards for Kite Pharma/Gilead and Seattle Genetics. M.R.B. serves as a consultant and/or advisor for Celgene, Kite Pharma/Gilead, CRISPR Therapeutics, and Novartis and on speakers bureaus for Kite Pharma/Gilead, BMS, and Celgene, and has other financial interests/relationships with Novartis as a part of steering committees. P.D. serves on the advisory board for Kite Pharma/Gilead. B.D. serves as a consultant and/or advisor for Celgene and has received institutional research support from Angiocrine Bioscience, Celyad, and Poseida Therapeutics. S.A.G. has served as a consultant for CBMG, Novartis, Roche, GSK, Cure Genetics, Humanigen, and Jazz Pharmaceuticals; has received research funding from Novartis, Kite Pharma/Gilead, and Servier; and serves on study steering committees or scientific advisory boards for Jazz Pharmaceuticals and Adaptimmune. B.H.-L. and M.J. have no conflicts to disclose. R.T.M. has received honoraria/consultant fees from BMS/JUNO, CRISPR Therapeutics, Kite Pharma/Gilead, Incyte, Intellia Therapeutics, Kadmon, Omeros, and PACT Pharma; serves on a scientific board for Artiva Biotherapeutics; has served on data and safety monitoring boards for Novartis and Athersys; served as chair of the scientific steering committee for the phase II tisagenlecleucel study sponsored by Novartis; and has received research support from Novartis. He also holds patents from Athersys. J.P.M. has received research/grant support from Novartis, Fresenius Biotech, Astellas, Bellicum Pharmaceuticals, Gamida Cell, and Pluristem; has served on advisory boards/speakers bureaus for and received travel accommodations and expenses and research funding from Kite Pharma/Gilead and BMS/JUNO; and has received honoraria, travel expenses along with grant/research funding from AlloVir. L.J.N. has received honoraria from Bayer, Celgene, Gamida Cell, Genentech, Kite Pharma/Gilead, Novartis, MEI, and TG Therapeutics along with research support from Celgene, Genentech, Karus Therapeutics, Merck, Novartis, and TG Therapeutics. O.O.O. has served on scientific advisory boards for Pfizer, Spectrum, Bayer, and Kite Pharma/Gilead; has received honoraria from Pfizer; and has received research support from Novartis. M.-A.P. has received honoraria from AbbVie, Bellicum, BMS, Incyte, Merck, Novartis, Nektar Therapeutics, Omeros, and Takeda; serves on data safety and monitoring boards for Servier and Medigene and on scientific advisory boards of MolMed and NexImmune; and has received research support for clinical trials from Incyte, Kite Pharma/Gilead, Miltenyi Biotec, and Novartis. D.L.P. reports spousal employment along with stock and other ownership interests in Genentech and Roche; has served in a consulting/advisory capacity for Novartis, Kite Pharma/Gilead, Incyte, Gerson Lehrman Group, Glenmark, and Janssen; has received travel expenses from Kite Pharma and Novartis; has received research funding from Novartis; is a listed as an inventor on a patent for CTL019; and serves on the Board of Directors of the National Marrow Donor Program and on the Board Examination Writing Committee of the American Board of Internal Medicine. P.A.R. has served on speakers bureaus for Kite Pharma/Gilead and Bayer and on advisory boards for Verastem Oncology, Novartis, Celgene/BMS, and Bayer; has received honoraria from Novartis; and has received research support from Celgene/BMS, Kite Pharma, and Novartis., (Copyright © 2020 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Chimeric Antigen Receptor (CAR) T cell therapies - adoptive T cell therapies that have been genetically engineered for a new antigen-specificity - have displayed significant success in treating patients with hematologic malignancies, leading to three recent US Food and Drug Administration approvals. Based on the promise generated from these successes, the field is rapidly evolving to include new disease indications and CAR designs, while simultaneously reviewing and optimizing toxicity and management protocols. As such, this review provides expert perspective on the significance and clinical considerations of CAR T cell therapies in order to provide timely information to clinicians about this revolutionary new therapeutic class.

Chimeric antigen receptor (CAR)-modified T cells are being investigated in many settings, including classical Hodgkin lymphoma (cHL). The unique biology of cHL, characterized by scant Hodgkin and Reed-Sternberg (HRS) cells within an immunosuppressive tumor microenvironment (TME), may pose challenges for cellular therapies directly targeting antigens expressed on HRS cells. We hypothesized that eradicating CD19 + B cells within the TME and the putative circulating CD19 + HRS clonotypic cells using anti-CD19-directed CAR-modified T cells (CART19) may indirectly affect HRS cells, which do not express CD19. Here we describe our pilot trial using CART19 in patients with relapsed or refractory cHL. To limit potential toxicities, we used nonviral RNA CART19 cells, which are expected to express CAR protein for only a few days, as opposed to CART19 generated by viral vector transduction, which expand in vivo and retain CAR expression. All 5 enrolled patients underwent successful manufacturing of nonviral RNA CART19, and 4 were infused with protocol-specified cell dose. There were no severe toxicities. Responses were seen, but these were transient. To our knowledge, this is the first CART19 clinical trial to use nonviral RNA gene delivery. This trial was registered at www.clinicaltrials.gov as #NCT02277522 (adult) and #NCT02624258 (pediatric)., (© 2018 by The American Society of Hematology.)

Cancer immunotherapy based on genetically redirecting T cells has been used successfully to treat B cell malignancies 1-3 . In this strategy, the T cell genome is modified by integration of viral vectors or transposons encoding chimaeric antigen receptors (CARs) that direct tumour cell killing. However, this approach is often limited by the extent of expansion and persistence of CAR T cells 4,5 . Here we report mechanistic insights from studies of a patient with chronic lymphocytic leukaemia treated with CAR T cells targeting the CD19 protein. Following infusion of CAR T cells, anti-tumour activity was evident in the peripheral blood, lymph nodes and bone marrow; this activity was accompanied by complete remission. Unexpectedly, at the peak of the response, 94% of CAR T cells originated from a single clone in which lentiviral vector-mediated insertion of the CAR transgene disrupted the methylcytosine dioxygenase TET2 gene. Further analysis revealed a hypomorphic mutation in this patient's second TET2 allele. TET2-disrupted CAR T cells exhibited an epigenetic profile consistent with altered T cell differentiation and, at the peak of expansion, displayed a central memory phenotype. Experimental knockdown of TET2 recapitulated the potency-enhancing effect of TET2 dysfunction in this patient's CAR T cells. These findings suggest that the progeny of a single CAR T cell induced leukaemia remission and that TET2 modification may be useful for improving immunotherapies.

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Lymphocyte trafficking via chemokine receptors such as CCR5 plays a critical role in alloreactive responses, and previous data suggest that CCR5 blockade with maraviroc results in a low incidence of visceral GVHD. However, the full scope of clinical and immunologic effects of CCR5 blockade in HSCT has not been described. We compared a cohort of patients enrolled on a trial of reduced-intensity allo-HSCT with standard GVHD prophylaxis plus maraviroc to a contemporary control cohort receiving standard GVHD prophylaxis alone. Maraviroc treatment was associated with a lower incidence of acute GVHD without increased risk of disease relapse, as well as reduced levels of gut-specific markers. At day 30, maraviroc treatment increased CCR5 expression on T cells and dampened T-cell activation in peripheral blood without impairing early immune reconstitution or increasing risk for infections. Patients who developed acute GVHD despite maraviroc prophylaxis showed increased T-cell activation, naive T-cell skewing, and elevated serum CXCL9 and CXCL10 levels. Collectively, these data suggest that maraviroc effectively protects against GVHD by modulating alloreactive donor T-cell responses, and that CXCR3 signaling may be an important resistance mechanism to CCR5 blockade in GVHD., (© 2017 by The American Society of Hematology.)

Hematopoietic cell transplantation (HCT) remains an important and potentially curative option for most hematologic malignancies. As a form of immunotherapy, allogeneic HCT (allo-HCT) offers the potential for durable remissions but is limited by transplantation- related morbidity and mortality owing to organ toxicity, infection, and graft-versus-host disease. The recent positive outcomes of chimeric antigen receptor T (CART) cell therapy in B cell malignancies may herald a paradigm shift in the management of these disorders and perhaps other hematologic malignancies as well. Clinical trials are now needed to address the relative roles of CART cells and HCT in the context of transplantation-eligible patients. In this review, we summarize the state of the art of the development of CART cell therapy for leukemia, lymphoma, and myeloma and discuss our perspective of how CART cell therapy can be applied in the context of HCT., Competing Interests: The authors work under a research collaboration involving the University of Pennsylvania and the Novartis Institutes of Biomedical Research, Inc. S.S.K, D.L.P and S.G. are inventors of intellectual property licensed by the University of Pennsylvania to Novartis., (Copyright © 2017 The American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)

Chimeric antigen receptors (CARs) are engineered molecules that can be introduced into T cells to enable them to target specific tumor antigens. CAR T cells targeting CD19 have shown promise in patients with relapsed and refractory B-cell neoplasms, including those with acute lymphoblastic leukemia, chronic lymphocytic leukemia, and non-Hodgkin lymphomas. Notably, durable responses have been observed in patients who had not undergone consolidative stem cell transplant, a finding that correlates with reports of T-cell persistence and B-cell aplasia in studies of anti-CD19 treatment in vivo. Cytokine release syndrome, correlating with activation and expansion of T cells, and neurologic toxicity are the most significant treatment-related adverse effects. Efforts are underway to extend the benefits of immunotherapy with anti-CD19 CAR T cells to other targets and tumor types.

The mechanisms underlying the maintenance of long-lasting humoral immunity are not well understood. Studies in mice indicate that plasma cells (PCs) can survive up to a lifetime, even in the absence of regeneration by B cells, implying the presence of long-lived PCs as a mechanism for long-lasting immunity. Evidence from humans treated with anti-CD20, which depletes circulating B cells, also suggests B-cell-independent long-term survival of some PCs. On the other hand, antibody responses may be sustained solely by short-lived PCs with repopulation from clonally related memory B cells. To explore PC longevity and humoral immunity in humans, we investigated the fate of PCs and their antibodies in adult and pediatric patients who received chimeric antigen receptor-based adoptive T-cell immunotherapy targeting CD19 to treat B-cell lineage malignancies (CTL019). Treatment with CTL019 is frequently associated with B-cell aplasia that can persist for years. Serum antibody titers to vaccine-related antigens were measured, and quantitative assessment of B cells and PCs in blood and bone marrow was performed at various time points before and after CTL019 therapy. While total serum immunoglobulin concentrations decline following CTL019-induced B-cell aplasia, several vaccine/pathogen-specific serum immunoglobulin G and A (IgG and IgA) titers remain relatively stable for at least 6 and 12 months posttreatment, respectively. Analysis of bone marrow biopsies after CTL019 revealed 8 patients with persistence of antibody-secreting PCs at least 25 months post-CTL019 infusion despite absence of CD19(+)CD20(+) B cells. These results provide strong evidence for the existence of memory B-cell-independent, long-lived PCs in humans that contribute to long-lasting humoral immunity., (© 2016 by The American Society of Hematology.)

Chimeric antigen receptor (CAR) T cell therapy of cancer is generating enormous enthusiasm. Twenty-five years after the concept was first proposed, major advances in molecular biology, virology, and good manufacturing practices (GMP)-grade cell production have transformed antibody-T cell chimeras from a scientific curiosity to a fact of life for academic cellular immunotherapy researchers and, increasingly, for patients. In this review, we explain the preclinical concept, outline how it has been translated to the clinic, and draw lessons from the first years of CAR T cell therapy for the practicing clinician., (Copyright © 2015. Published by Elsevier Ltd.)

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy is highly promising but requires robust T-cell expansion and engraftment. A T-cell defect in chronic lymphocytic leukemia (CLL) due to disease and/or therapy impairs ex vivo expansion and response to CAR T cells. To evaluate the effect of ibrutinib treatment on the T-cell compartment in CLL as it relates to CAR T-cell generation, we examined the phenotype and function of T cells in a cohort of CLL patients during their course of treatment with ibrutinib. We found that ≥5 cycles of ibrutinib therapy improved the expansion of CD19-directed CAR T cells (CTL019), in association with decreased expression of the immunosuppressive molecule programmed cell death 1 on T cells and of CD200 on B-CLL cells. In support of these findings, we observed that 3 CLL patients who had been treated with ibrutinib for ≥1 year at the time of T-cell collection had improved ex vivo and in vivo CTL019 expansion, which correlated positively together and with clinical response. Lastly, we show that ibrutinib exposure does not impair CAR T-cell function in vitro but does improve CAR T-cell engraftment, tumor clearance, and survival in human xenograft models of resistant acute lymphocytic leukemia and CLL when administered concurrently. Our collective findings indicate that ibrutinib enhances CAR T-cell function and suggest that clinical trials with combination therapy are warranted. Our studies demonstrate that improved T-cell function may also contribute to the efficacy of ibrutinib in CLL. These trials were registered at www.clinicaltrials.gov as #NCT01747486, #NCT01105247, and #NCT01217749., (© 2016 by The American Society of Hematology.)

Chimeric antigen receptors (CARs) can be introduced into T-cells redirecting them to target specific tumor antigens. CAR-modified T cells targeting CD19 have shown remarkable activity against CD19+ malignancies including B cell acute lymphocytic leukemia (ALL), chronic lymphocytic leukemia (CLL), and non-Hodgkin lymphomas (NHL). Complete remission rates as high as 90% have been observed for patients with relapsed and refractory ALL and greater than 50% response rates have been seen in heavily pre-treated CLL and NHL. Excitingly, some remissions have been durable without any additional therapy, a finding which correlates with in-vivo T-cell persistence and B-cell aplasia. The major treatment related toxicities include B-cell aplasia, neurologic toxicities, and a potentially severe cytokine release syndrome. This review summarizes outcomes for patients treated with CD19-CAR T-cells while exploring the field's challenges and future directions., (© 2015 Wiley Periodicals, Inc.)

Patients with multiply relapsed or refractory chronic lymphocytic leukemia (CLL) have a poor prognosis. Chimeric antigen receptor (CAR)-modified T cells targeting CD19 have the potential to improve on the low complete response rates with conventional therapies by inducing sustained remissions in patients with refractory B cell malignancies. We previously reported preliminary results on three patients with refractory CLL. We report the mature results from our initial trial using CAR-modified T cells to treat 14 patients with relapsed and refractory CLL. Autologous T cells transduced with a CD19-directed CAR (CTL019) lentiviral vector were infused into patients with relapsed/refractory CLL at doses of 0.14 × 10(8) to 11 × 10(8) CTL019 cells (median, 1.6 × 10(8) cells). Patients were monitored for toxicity, response, expansion, and persistence of circulating CTL019 T cells. The overall response rate in these heavily pretreated CLL patients was 8 of 14 (57%), with 4 complete remissions (CR) and 4 partial remissions (PR). The in vivo expansion of the CAR T cells correlated with clinical responses, and the CAR T cells persisted and remained functional beyond 4 years in the first two patients achieving CR. No patient in CR has relapsed. All responding patients developed B cell aplasia and experienced cytokine release syndrome, coincident with T cell proliferation. Minimal residual disease was not detectable in patients who achieved CR, suggesting that disease eradication may be possible in some patients with advanced CLL., (Copyright © 2015, American Association for the Advancement of Science.)

Over the past decade the development of safer reduced-intensity conditioning regimens, expanded donor pools, advances in supportive care, and prevention/management of graft-versus-host disease have expanded stem cell transplantation (SCT) availability for chronic lymphocytic leukemia (CLL) patients. However, there are now increasingly active treatment options available for CLL patients with favorable toxicity profiles and convenient administration schedules. This raises the critical issue of whether or not attainment of cure remains a necessary goal. It is now less clear that treatment with curative intention and with significant toxicity is required for long-term survival in CLL. In addition, the demonstrated safety and activity of genetically modified chimeric antigen receptor (CAR) T cells present the opportunity of harnessing the power of the immune system to kill CLL cells without the need for SCT. We attempt to define the role of SCT in the era of targeted therapies and discuss questions that remain to be answered. Furthermore, we highlight the potential for exciting new cellular therapy using genetically modified anti-CD19 CAR T cells and discuss its potential to alter treatment paradigms for CLL., (© 2015 by The American Society of Hematology.)

Background: Relapsed acute lymphoblastic leukemia (ALL) is difficult to treat despite the availability of aggressive therapies. Chimeric antigen receptor-modified T cells targeting CD19 may overcome many limitations of conventional therapies and induce remission in patients with refractory disease., Methods: We infused autologous T cells transduced with a CD19-directed chimeric antigen receptor (CTL019) lentiviral vector in patients with relapsed or refractory ALL at doses of 0.76×10(6) to 20.6×10(6) CTL019 cells per kilogram of body weight. Patients were monitored for a response, toxic effects, and the expansion and persistence of circulating CTL019 T cells., Results: A total of 30 children and adults received CTL019. Complete remission was achieved in 27 patients (90%), including 2 patients with blinatumomab-refractory disease and 15 who had undergone stem-cell transplantation. CTL019 cells proliferated in vivo and were detectable in the blood, bone marrow, and cerebrospinal fluid of patients who had a response. Sustained remission was achieved with a 6-month event-free survival rate of 67% (95% confidence interval [CI], 51 to 88) and an overall survival rate of 78% (95% CI, 65 to 95). At 6 months, the probability that a patient would have persistence of CTL019 was 68% (95% CI, 50 to 92) and the probability that a patient would have relapse-free B-cell aplasia was 73% (95% CI, 57 to 94). All the patients had the cytokine-release syndrome. Severe cytokine-release syndrome, which developed in 27% of the patients, was associated with a higher disease burden before infusion and was effectively treated with the anti-interleukin-6 receptor antibody tocilizumab., Conclusions: Chimeric antigen receptor-modified T-cell therapy against CD19 was effective in treating relapsed and refractory ALL. CTL019 was associated with a high remission rate, even among patients for whom stem-cell transplantation had failed, and durable remissions up to 24 months were observed. (Funded by Novartis and others; CART19 ClinicalTrials.gov numbers, NCT01626495 and NCT01029366.).

It is now well established that the immune system can control and eliminate cancer cells. Adoptive T cell transfer has the potential to overcome the significant limitations associated with vaccine-based strategies in patients who are often immune compromised. Application of the emerging discipline of synthetic biology to cancer, which combines elements of genetic engineering and molecular biology to create new biological structures with enhanced functionalities, is the subject of this focused research review.

Purpose: To characterize relationships between specific immune cell subsets in bone marrow (BM) or granulocyte colony-stimulating factor-mobilized peripheral blood (PB) stem cells collected from unrelated donors and clinical outcomes of patients undergoing transplantation in BMTCTN 0201., Patients and Methods: Fresh aliquots of 161 BM and 147 PB stem-cell allografts from North American donors randomly assigned to donate BM or PB stem cells and numbers of transplanted cells were correlated with overall survival (OS), relapse, and graft-versus-host disease (GvHD)., Results: Patients with evaluable grafts were similar to all BMTCTN 0201 patients. The numbers of plasmacytoid dendritic cells (pDCs) and naïve T cells (Tns) in BM allografts were independently associated with OS in multivariable analyses including recipient and donor characteristics, such as human leukocyte antigen mismatch, age, and use of antithymocyte globulin. BM recipients of > median number of pDCs, naïve CD8(+) T cells (CD8Tns), or naïve CD4(+) T cells (CD4Tns) had better 3-year OS (pDCs, 56% v 35%; P = .025; CD8Tns, 56% v 37%; P = .012; CD4Tns, 55% v 37%; P = .009). Transplantation of more BM Tns was associated with less grade 3 to 4 acute GvHD but similar rates of relapse. Transplantation of more BM pDCs was associated with fewer deaths resulting from GvHD or from graft rejection. Analysis of PB grafts did not identify a donor cell subset significantly associated with OS, relapse, or GvHD., Conclusion: Donor immune cells in BM but not PB stem-cell grafts were associated with survival after unrelated-donor allogeneic hematopoietic stem-cell transplantation. The biologic activity of donor immune cells in allogeneic transplantation varied between graft sources. Donor grafts with more BM-derived Tns and pDCs favorably regulated post-transplantation immunity in allogeneic hematopoietic stem-cell transplantation., (© 2014 by American Society of Clinical Oncology.)

T cells redirected to specific antigen targets with engineered chimeric antigen receptors (CARs) are emerging as powerful therapies in hematologic malignancies. Various CAR designs, manufacturing processes, and study populations, among other variables, have been tested and reported in over 10 clinical trials. Here, we review and compare the results of the reported clinical trials and discuss the progress and key emerging factors that may play a role in effecting tumor responses. We also discuss the outlook for CAR T-cell therapies, including managing toxicities and expanding the availability of personalized cell therapy as a promising approach to all hematologic malignancies. Many questions remain in the field of CAR T cells directed to hematologic malignancies, but the encouraging response rates pave a wide road for future investigation.

Many patients with acute myeloid leukemia (AML) are incurable with chemotherapy and may benefit from novel approaches. One such approach involves the transfer of T cells engineered to express chimeric antigen receptors (CARs) for a specific cell-surface antigen. This strategy depends upon preferential expression of the target on tumor cells. To date, the lack of AML-specific surface markers has impeded development of such CAR-based approaches. CD123, the transmembrane α chain of the interleukin-3 receptor, is expressed in the majority of AML cells but is also expressed in many normal hematopoietic cells. Here, we show that CD123 is a good target for AML-directed CAR therapy, because its expression increases over time in vivo even in initially CD123(dim) populations, and that human CD123-redirected T cells (CART123) eradicate primary AML in immunodeficient mice. CART123 also eradicated normal human myelopoiesis, a surprising finding because anti-CD123 antibody-based strategies have been reportedly well tolerated. Because AML is likely preceded by clonal evolution in "preleukemic" hematopoietic stem cells, our observations support CART123 as a viable AML therapy, suggest that CART123-based myeloablation may be used as a novel conditioning regimen for hematopoietic cell transplantation, and raise concerns for the use of CART123 without such a rescue strategy.

Introduction: Malignancies of the B lymphocyte or its precursor include B-cell non-Hodgkin lymphoma as well as chronic and acute lymphoid leukemias. These are among the most common hematologic malignancies and many patients with B-cell malignancies are incurable. Although most patients initially respond to first-line treatment, relapse is frequent and is associated with a poor prognosis. T cells that are genetically engineered to express chimeric antigen receptors (CARs) recognizing the B-cell-associated molecule CD19 have emerged as a potentially potent and exciting therapeutic modality in recent years., Areas Covered: This review explores the current peer-reviewed publications in the field and a discussion of expert opinion., Expert Opinion: Genetic engineering of T cells has become clinically feasible and appears to be safe. Here we provide an insight into the process of patient selection, engineered T-cell production, infusion procedure, expected toxicities and efficacy of this exciting approach as it is practiced in the treatment of B-cell malignancies. Anti-CD19-redirected T cells likely represent the vanguard of an exciting new approach to treating cancer.

Chimeric antigen receptor-modified T cells with specificity for CD19 have shown promise in the treatment of chronic lymphocytic leukemia (CLL). It remains to be established whether chimeric antigen receptor T cells have clinical activity in acute lymphoblastic leukemia (ALL). Two children with relapsed and refractory pre-B-cell ALL received infusions of T cells transduced with anti-CD19 antibody and a T-cell signaling molecule (CTL019 chimeric antigen receptor T cells), at a dose of 1.4×10(6) to 1.2×10(7) CTL019 cells per kilogram of body weight. In both patients, CTL019 T cells expanded to a level that was more than 1000 times as high as the initial engraftment level, and the cells were identified in bone marrow. In addition, the chimeric antigen receptor T cells were observed in the cerebrospinal fluid (CSF), where they persisted at high levels for at least 6 months. Eight grade 3 or 4 adverse events were noted. The cytokine-release syndrome and B-cell aplasia developed in both patients. In one child, the cytokine-release syndrome was severe; cytokine blockade with etanercept and tocilizumab was effective in reversing the syndrome and did not prevent expansion of chimeric antigen receptor T cells or reduce antileukemic efficacy. Complete remission was observed in both patients and is ongoing in one patient at 11 months after treatment. The other patient had a relapse, with blast cells that no longer expressed CD19, approximately 2 months after treatment. Chimeric antigen receptor-modified T cells are capable of killing even aggressive, treatment-refractory acute leukemia cells in vivo. The emergence of tumor cells that no longer express the target indicates a need to target other molecules in addition to CD19 in some patients with ALL.

Background: Graft-versus-host disease (GVHD) is a major barrier to successful allogeneic hematopoietic stem-cell transplantation (HSCT). The chemokine receptor CCR5 appears to play a role in alloreactivity. We tested whether CCR5 blockade would be safe and limit GVHD in humans., Methods: We tested the in vitro effect of the CCR5 antagonist maraviroc on lymphocyte function and chemotaxis. We then enrolled 38 high-risk patients in a single-group phase 1 and 2 study of reduced-intensity allogeneic HSCT that combined maraviroc with standard GVHD prophylaxis., Results: Maraviroc inhibited CCR5 internalization and lymphocyte chemotaxis in vitro without impairing T-cell function or formation of hematopoietic-cell colonies. In 35 patients who could be evaluated, the cumulative incidence rate (±SE) of grade II to IV acute GVHD was low at 14.7±6.2% on day 100 and 23.6±7.4% on day 180. Acute liver and gut GVHD were not observed before day 100 and remained uncommon before day 180, resulting in a low cumulative incidence of grade III or IV GVHD on day 180 (5.9±4.1%). The 1-year rate of death that was not preceded by disease relapse was 11.7±5.6% without excessive rates of relapse or infection. Serum from patients receiving maraviroc prevented CCR5 internalization by CCL5 and blocked T-cell chemotaxis in vitro, providing evidence of antichemotactic activity., Conclusions: In this study, inhibition of lymphocyte trafficking was a specific and potentially effective new strategy to prevent visceral acute GVHD. (Funded by Pfizer and others; ClinicalTrials.gov number, NCT00948753.).

We designed a lentiviral vector expressing a chimeric antigen receptor with specificity for the B-cell antigen CD19, coupled with CD137 (a costimulatory receptor in T cells [4-1BB]) and CD3-zeta (a signal-transduction component of the T-cell antigen receptor) signaling domains. A low dose (approximately 1.5×10(5) cells per kilogram of body weight) of autologous chimeric antigen receptor-modified T cells reinfused into a patient with refractory chronic lymphocytic leukemia (CLL) expanded to a level that was more than 1000 times as high as the initial engraftment level in vivo, with delayed development of the tumor lysis syndrome and with complete remission. Apart from the tumor lysis syndrome, the only other grade 3/4 toxic effect related to chimeric antigen receptor T cells was lymphopenia. Engineered cells persisted at high levels for 6 months in the blood and bone marrow and continued to express the chimeric antigen receptor. A specific immune response was detected in the bone marrow, accompanied by loss of normal B cells and leukemia cells that express CD19. Remission was ongoing 10 months after treatment. Hypogammaglobulinemia was an expected chronic toxic effect.

Tumor immunotherapy with T lymphocytes, which can recognize and destroy malignant cells, has been limited by the ability to isolate and expand T cells restricted to tumor-associated antigens. Chimeric antigen receptors (CARs) composed of antibody binding domains connected to domains that activate T cells could overcome tolerance by allowing T cells to respond to cell surface antigens; however, to date, lymphocytes engineered to express CARs have demonstrated minimal in vivo expansion and antitumor effects in clinical trials. We report that CAR T cells that target CD19 and contain a costimulatory domain from CD137 and the T cell receptor ζ chain have potent non-cross-resistant clinical activity after infusion in three of three patients treated with advanced chronic lymphocytic leukemia (CLL). The engineered T cells expanded >1000-fold in vivo, trafficked to bone marrow, and continued to express functional CARs at high levels for at least 6 months. Evidence for on-target toxicity included B cell aplasia as well as decreased numbers of plasma cells and hypogammaglobulinemia. On average, each infused CAR-expressing T cell was calculated to eradicate at least 1000 CLL cells. Furthermore, a CD19-specific immune response was demonstrated in the blood and bone marrow, accompanied by complete remission, in two of three patients. Moreover, a portion of these cells persisted as memory CAR(+) T cells and retained anti-CD19 effector functionality, indicating the potential of this major histocompatibility complex-independent approach for the effective treatment of B cell malignancies.

The success of reduced intensity conditioning (RIC) transplantation is largely dependent on alloimmune effects. It is critical to determine whether immune modulation with anti-T-cell antibody infusion abrogates the therapeutic benefits of transplantation. We examined 1676 adults undergoing RIC transplantation for hematologic malignancies. All patients received alkylating agent plus fludarabine; 792 received allografts from a human leukocyte antigen-matched sibling, 884 from a 7 or 8 of 8 HLA-matched unrelated donor. Using Cox regression, outcomes after in vivo T-cell depletion (n = 584 antithymocyte globulin [ATG]; n = 213 alemtuzumab) were compared with T cell- replete (n = 879) transplantation. Grade 2 to 4 acute GVHD was lower with alemtuzumab compared with ATG or T cell- replete regimens (19% vs 38% vs 40%, P < .0001) and chronic GVHD, lower with alemtuzumab, and ATG regimens compared with T-replete approaches (24% vs 40% vs 52%, P < .0001). However, relapse was more frequent with alemtuzumab and ATG compared with T cell-replete regimens (49%, 51%, and 38%, respectively, P < .001). Disease-free survival was lower with alemtuzumab and ATG compared with T cell-replete regimens (30%, 25%, and 39%, respectively, P < .001). Corresponding probabilities of overall survival were 50%, 38%, and 46% (P = .008). These data suggest adopting a cautious approach to routine use of in vivo T-cell depletion with RIC regimens.

Immunodeficiency is a barrier to successful vaccination in individuals with cancer and chronic infection. We performed a randomized phase 1/2 study in lymphopenic individuals after high-dose chemotherapy and autologous hematopoietic stem cell transplantation for myeloma. Combination immunotherapy consisting of a single early post-transplant infusion of in vivo vaccine-primed and ex vivo costimulated autologous T cells followed by post-transplant booster immunizations improved the severe immunodeficiency associated with high-dose chemotherapy and led to the induction of clinically relevant immunity in adults within a month after transplantation. Immune assays showed accelerated restoration of CD4 T-cell numbers and function. Early T-cell infusions also resulted in significantly improved T-cell proliferation in response to antigens that were not contained in the vaccine, as assessed by responses to staphylococcal enterotoxin B and cytomegalovirus antigens (P < 0.05). In the setting of lymphopenia, combined vaccine therapy and adoptive T-cell transfer fosters the development of enhanced memory T-cell responses.

We explored the feasibility and toxicity of administering escalating doses of anti-CD3/CD28 ex vivo costimulated T cells as a therapeutic adjunct for patients with relapsed, refractory, or chemotherapy-resistant, aggressive non-Hodgkin lymphoma (NHL) following high-dose chemotherapy and CD34+-selected hematopoietic cell transplantation (HCT). Sixteen patients had infusions on day 14 after HCT of autologous T cells that had been stimulated using beads coated with anti-CD3 and anti-CD28 monoclonal antibodies. At baseline, the subjects had severe quantitative and functional T-cell impairments. The culture procedure partially reversed impaired cytokine responsiveness in T cells in vitro and in vivo. Transient dose-dependent infusion toxicities were observed. There was a rapid reconstitution of lymphocytes; however, there were persistent defects in CD4 T cells. Most interestingly, 5 patients had a delayed lymphocytosis between day 30 and day 120 after HCT. Maximal clinical responses included 5 patients with a complete response (CR), 7 patients with a partial response (PR), and 4 patients with stable disease. At a median follow-up of 33 months (range, 26-60 months), 5 patients are alive with stable or relapsed disease and 3 patients remain in CR. In conclusion, this phase 1 trial demonstrates that adoptive transfer of autologous costimulated T cells (1) is feasible in heavily pretreated patients with advanced NHL, (2) is associated with a rapid recovery of lymphocyte counts, (3) reverses cytokine activation deficits in vitro, and (4) is associated with delayed lymphocytosis in a subset of patients.