Toward Better Understanding and Management of CAR-T Cell–Associated Toxicity

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Andrea Schmidts ◽  
Marc Wehrli ◽  
Marcela V. Maus
Keyword(s):  
T Cells ◽  
T Cell ◽  
Hematological Malignancies ◽  
Lymphoblastic Leukemia ◽  
B Cell Lymphoma ◽  
Annual Review ◽  
Publication Date ◽  
Special Focus ◽  
Car T Cell ◽  
Car T

Adoptive transfer of T cells modified with chimeric antigen receptors (CAR-T cells) has changed the therapeutic landscape of hematological malignancies, particularly for acute lymphoblastic leukemia and large B cell lymphoma, where two different CAR-T products are now considered standard of care. Furthermore, intense research efforts are under way to expand the clinical application of CAR-T cell therapy for the benefit of patients suffering from other types of cancers. Nevertheless, CAR-T cell treatment is associated with toxicities such as cytokine release syndrome, which can range in severity from mild flu-like symptoms to life-threatening vasodilatory shock, and a neurological syndrome termed ICANS (immune effector cell–associated neurotoxicity syndrome), which can also range in severity from a temporary cognitive deficit lasting only a few hours to lethal cerebral edema. In this review, we provide an in-depth discussion of different types of CAR-T cell–associated toxicities, including an overview of clinical presentation and grading, pathophysiology, and treatment options. We also address future perspectives and opportunities, with a special focus on hematological malignancies. Expected final online publication date for the Annual Review of Medicine, Volume 72 is January 27, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals CAR T-Cell Immunotherapy in Human and Veterinary Oncology: Changing the Odds against Hematological Malignancies

2018 ◽  
Author(s):  
Jonathan P Mochel ◽  
Stephen C Ekker ◽  
Chad M Johannes ◽  
Albert E Jergens ◽  
Karin Allenspach ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Hematological Malignancies ◽  
B Cell Lymphoma ◽  
Car T Cells ◽  
Car T Cell ◽  
Oncology Research ◽  
Cell Immunotherapy ◽  
Car T ◽  
T Cell Immunotherapy

The advent of the genome editing era brings forth the promise of adoptive cell transfer using engineered chimeric antigen receptor (CAR) T-cells for targeted cancer therapy. CAR T-cell immunotherapy is probably one of the most encouraging developments for the treatment of hematological malignancies. In 2017, two CAR T-cell therapies were approved by the U. S Food and Drug Administration; one for the treatment of pediatric Acute Lymphoblastic Leukemia (ALL), the other for adult patients with advanced lymphomas. However, despite significant progress in the area, CAR T-cell therapy is still in its early days and faces significant challenges, including the complexity and costs associated with the technology. B-cell lymphoma is the most common hematopoietic cancer in dogs, with an incidence approaching 0.1% and a total of 20-100 cases per 100,000 individuals. It is a widely accepted naturally occurring model for human non-Hodgkin’s lymphoma. Current treatment is with combination chemotherapy protocols, which prolong life for less than a year in canines and are associated with severe dose-limiting side effects, such as gastrointestinal and bone marrow toxicity. To date, one canine study generated CAR T-cells by transfection of mRNA for CAR domain expression. While this was shown to provide a transient anti-tumor activity, results were modest, indicating that stable, genomic integration of CAR modules is required in order to achieve lasting therapeutic benefit. This Commentary summarizes the current state of knowledge on CAR T-cell immunotherapy in human medicine and its potential applications in animal health, while discussing the potential of the canine model as a translational system for immuno-oncology research.

scholarly journals Development of Novel Anti-CD10 Target Modules for Redirection of Universal CAR T Cells Against CD10-Positive Malignancies

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 5612-5612 ◽  
Author(s):  
Anja Feldmann ◽  
Stefanie Koristka ◽  
Claudia Arndt ◽  
Liliana Raquel Loureiro ◽  
Ralf Bergmann ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Cells ◽  
Hematological Malignancies ◽  
Lymphoblastic Leukemia ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

The common acute lymphoblastic leukemia antigen CD10 is a marker for several hematological malignancies, including acute lymphoblastic leukemia as well as T and B cell lymphomas, Burkitt lymphomas, and some solid tumors like renal cell carcinomas, pancreatic tumors and melanomas. Because of its tumor related expression pattern, CD10 is an attractive target for adoptively transferred T cells that are genetically modified to express chimeric antigen receptors (CARs). Recently, conventional CAR T cell therapy targeting CD19-positive hematological malignancies was clinically approved because of its impressive effectiveness in patients. However, CAR T cells can also cause severe side effects like on-target, off-tumor reactions, tumor lysis syndrome and cytokine release syndrome. Most critically, activity of conventional CAR T cells cannot be controlled, once they are applied in patients. As CD10 is also widely expressed on normal tissues, CAR T cell reactivity has to be controllable in order to stop CAR T cell therapy in case of on-target, off-tumor toxicities occur. Especially for this purpose, we have recently established a switchable, modular and universal CAR platform technology, named UniCAR system, which can be repeatedly turned on and off. In contrast to conventional CARs, that directly recognize a tumor-associated antigen (TAA) on the tumor cell surface via their extracellular single-chain variable fragment (scFv), the UniCAR system is structured in a modular manner of two components. The first component are T cells genetically engineered to express UniCARs and the second component are target modules (TMs). Most importantly, UniCARs cannot directly bind to a TAA because their extracellular scFv is directed against the peptide epitope E5B9 which is not present on the surface of living cells. Consequently, UniCAR armed T cells are per se inert. They can be redirected towards tumor cells only via a TM. TMs consist of a scFv targeting a TAA and the epitope E5B9 recognized by UniCARs allowing a cross-linkage of UniCAR T cells with tumor cells which results in T cell activation. As TMs have a very short half-life, UniCAR T cell activity can be controlled by dosing of the TM. Once the TM is administered, UniCAR T cells can be switched on, but once the TM injection is stopped and the TM is eliminated, UniCAR T cells are switched off immediately. Here, we show proof of concept for functionality of the UniCAR system targeting CD10-positive malignancies. Therefor, a novel anti-CD10 TM was constructed which is able to redirect UniCAR T cells to eliminate CD10-expressing tumor cells. In summary, we have established a universal, switchable, modular UniCAR platform technology that can be used to target CD10-positive malignancies. Disclosures Koristka: Intellia Therapeutics: Employment. Bachmann:GEMoaB Monoclonals: Equity Ownership, Patents & Royalties.

Chimeric Antigen Receptor-Engineered T-Cells - A New Way and Era for Lymphoma Treatment

2020 ◽  
Vol 14 (4) ◽  
pp. 312-323
Author(s):  
Romeo G. Mihăilă
Keyword(s):  
T Cells ◽  
T Cell ◽  
Response Rate ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Car T Cells ◽  
Future Developments ◽  
Car T Cell ◽  
Large B Cell Lymphoma ◽  
Car T

Background: Patients with refractory or relapsed diffuse large B-cell lymphoma have a poor prognosis with the current standard of care. Objective: Chimeric Antigen Receptor T-cells (CAR T-cells) are functionally reprogrammed lymphocytes, which are able to recognize and kill tumor cells. The aim of this study is to make progress in this area. Method: A mini-review was achieved using the articles published in Web of Science and PubMed in the last year and the new patents were made in this field. Results: The responses to CAR T-cell products axicabtagene ciloleucel and tisagenlecleucel are promising; the objective response rate can reach up to 83%, and the complete response rate ranges between 40 and 58%. About half of the patients may have serious side effects, such as cytokine release syndrome and neurotoxicity. Current and future developments include the improvement of CAR T-cell expansion and polyfunctionality, the combined use of CAR T-cells with a fusion protein between interferon and an anti-CD20 monoclonal antibody, with checkpoint inhibitors or small molecule sensitizers that have apoptotic-regulatory effects. Furthermore, the use of IL-12-expressing CAR T-cells, an improved technology for the production of CAR T-cells based on targeted nucleases, the widespread use of allogeneic CAR T-cells or universal CAR T-cells obtained from genetically engineered healthy donor T-cells are future developments actively considered. Conclusion: CAR T-cell therapy significantly improved the outcome of patients with relapsed or refractory diffuse large B-cell lymphoma. The advances in CAR T-cells production technology will improve the results and enable the expansion of this new immunotherapy.

scholarly journals Oligoclonal T Cells Transiently Expand and Express Tim-3 and PD-1 Following Anti-CD19 CAR T Cell Therapy: A Case Report

2018 ◽  
Vol 19 (12) ◽  
pp. 4118 ◽  
Author(s):  
Christopher Funk ◽  
Christopher Petersen ◽  
Neera Jagirdar ◽  
Sruthi Ravindranathan ◽  
David Jaye ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Hematologic Malignancy ◽  
Drug Application ◽  
B Cell Lymphoma ◽  
T Cell Subsets ◽  
Phenotypic Analysis ◽  
T Cell Therapy ◽  
Car T Cell ◽  
Car T

Clinical trials of chimeric antigen receptor (CAR) T cells in hematologic malignancy associate remissions with two profiles of CAR T cell proliferation kinetics, which differ based upon costimulatory domain. Additional T cell intrinsic factors that influence or predict clinical response remain unclear. To address this gap, we report the case of a 68-year-old woman with refractory/relapsed diffuse large B cell lymphoma (DLBCL), treated with tisagenlecleucel (anti-CD19), with a CD137 costimulatory domain (4-1BB) on an investigational new drug application (#16944). For two months post-infusion, the patient experienced dramatic regression of subcutaneous nodules of DLBCL. Unfortunately, her CAR T exhibited kinetics unassociated with remission, and she died of DLBCL-related sequelae. Serial phenotypic analysis of peripheral blood alongside sequencing of the β-peptide variable region of the T cell receptor (TCRβ) revealed distinct waves of oligoclonal T cell expansion with dynamic expression of immune checkpoint molecules. One week prior to CAR T cell contraction, T cell immunoglobulin mucin domain 3 (Tim-3) and programmed cell death protein 1 (PD-1) exhibited peak expressions on both the CD8 T cell (Tim-3 ≈ 50%; PD-1 ≈ 17%) and CAR T cell subsets (Tim-3 ≈ 78%; PD-1 ≈ 40%). These correlative observations draw attention to Tim-3 and PD-1 signaling pathways in context of CAR T cell exhaustion.

scholarly journals Successful 24-Hours Manufacture of Anti-CD19/CD22 Dual Chimeric Antigen Receptor (CAR) T Cell Therapy for B-Cell Acute Lymphoblastic Leukemia (B-ALL)

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 2-3
Author(s):  
Junfang Yang ◽  
Pengfei Jiang ◽  
Xian Zhang ◽  
Jingjing Li ◽  
Yan Wu ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
Lymphoblastic Leukemia ◽  
Observation Time ◽  
High Dose ◽  
T Cell Therapy ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

Introduction Multiple issues arise for a wider application of chimeric antigen receptor (CAR) T cell therapy including manufacturing time and antigen escape. Here we report data on an anti-CD19/CD22 dual CAR-T (GC022F) therapy based on a novel manufacturing platform, from a phase I clinical study (NCT04129099) in treating patients with B-cell acute lymphoblastic leukemia (B-ALL). Methods Peripheral blood (PB) mononuclear cells were obtained by leukapheresis. T-cells were separated and transduced with lentivirus that encodes a CD19/CD22 directed 4-1BB: ζ CAR. GC022F cells were manufactured using a novel FasTCARTM platform which takes 24 hours, while the conventional CD19/CD22 dual CAR-T (GC022C) cells used as parallel control in the preclinical study were manufactured by conventional process which typically takes 9-14 days. The phase I dose escalation study was initiated to explore the safety and efficacy of GC022F in patients with B-ALL. All patients received a conditioning regimen of IV fludarabine (25mg/m2/d) and cyclophosphamide (250mg/m2/d) for 3 days prior to GC022F infusion. Results When compared with the GC022C, GC022F cells showed 1) less exhaustion as indicated by lower percentage of PD-1+LAG3+ cells following co-culturing with tumor cells, 2) younger phenotypes as demonstrated by more abundant T central memory cells (Tcm; CCR7+CD45RA+ or CD45RO+CD62L+), 3) higher expansion fold at in vitro culture, and 4) high anti-leukemia efficacy in mice model (Fig.1). Comparing in vivo efficacy of GC022F with GC022C cells at lower doses, GC022F treatment were more potent and could reduce tumor burden earlier and faster, and led to significantly prolonged overall survival of the experimental animals. From Nov. 2019 to Jun. 2020, 9 children and 1 adult with B-ALL were enrolled and infused with GC022F, 2 in low-dose (6.0×104/kg), 7 in medium dose (1.0-1.5×105/kg), 1 in high-dose (2.25×105/kg). Patients' median observation time was 99 (14-210) days on the day of cut-off. Characteristics of enrolled patients are shown in Table 1. The median age was 10 (3-48) years, and the median bone marrow (BM) blasts were 21.0 (0.1-63.5) % at enrollment. Three patients had prior CD19 CAR-T cell therapy history and one of whom had prior allogeneic hematopoietic stem cell transplantation (allo-HSCT). After infusion, the median peak of circulating CAR-T cell copy number was 2.29 ×105 copies/µg genomic DNA (0.0014-5.66), which occurred around day 14 (day10 - day 28). Importantly, GC022F persisted well in PB with a median of 2.40×105 copies/µg genomic DNA (0.75-3.98) on day 28 in 5 of 9 patients with available 4 weeks of cellular kinetics data. GC022F exerted a superior safety profile with no observed grade ≥ 3 cytokine release syndrome (CRS) and neurotoxicity in all patients. Among those 6 patients with CRS, only 1 at high dose level had grade 2 CRS; only 1 developed grade 1 neurotoxicity. After GC022F infusion, 6/6 patients with BM blasts > 5% at enrollment achieved complete remission (CR) by day 28, 5/6 with minimal residual disease (MRD)-negative CR. For those 4 patients with MRD positive disease at enrollment, 3 became MRD-negative CR by day 28, 1 had persist MRD positive disease and withdrew from the study by 2 weeks. Five of 8 MRD-negative CR patients subsequently made a choice to pursue consolidation allo-HSCT with a median time interval of 57 (48-71) days post GC022F infusion and all have remained in MRD-negative CR except 1 died from graft-versus-host disease (GVHD) and infection 143 days post GC022F infusion. Of the other 3 patients without allo-HSCT, 2 relapsed with CD19+/CD22+ disease at 12-16 weeks follow-up, including the patient with prior history of CD19 CAR-T treatment and transplant. Conclusion This study demonstrated that anti-CD19/CD22 dual CAR T-cells could be successfully manufactured by FasTCARTM technology in 24 hours, with younger and less exhausted phenotypes. Moreover, the Dual FasTCAR-T cells showed more potent efficacy in xenograft mouse model compared to the conventional dual CAR-T cells. Our clinical data demonstrate that GC022F is safe and efficacious in treating patients with CD19+CD22+ B-ALL. More data on additional patients and longer observation time are needed to further evaluate CD19/CD22 dual FasTCAR-T cell product. Disclosures Cai: Gracell Biotechnologies Ltd: Current Employment. Wang:Gracell Biotechnologies Ltd: Current Employment. Chen:Gracell Biotechnologies Ltd: Current Employment. Ye:Gracell Biotechnologies Co., Ltd.: Current Employment. He:Gracell Biotechnologies Co., Ltd.: Current Employment. Cao:Gracell Biotechnologies Ltd: Current Employment. Sersch:Gracell Biotechnologies Co., Ltd.: Current Employment.

scholarly journals DLBCL patients treated with CD19 CAR T cells experience a high burden of organ toxicities but low nonrelapse mortality

2020 ◽  
Vol 4 (13) ◽  
pp. 3024-3033 ◽  
Author(s):  
Kitsada Wudhikarn ◽  
Martina Pennisi ◽  
Marta Garcia-Recio ◽  
Jessica R. Flynn ◽  
Aishat Afuye ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
B Cell Lymphoma ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T ◽  
Grade 3

Abstract Cytokine release syndrome (CRS) immune effector cell–associated neurotoxicity syndrome are the most notable toxicities of CD19 chimeric antigen receptor (CAR) T-cell therapy. In addition, CAR T-cell–mediated toxicities can involve any organ system, with varied impacts on outcomes, depending on patient factors and involved organs. We performed detailed analysis of organ-specific toxicities and their association with outcomes in 60 patients with diffuse large B-cell lymphoma (DLBCL) treated with CD19 CAR T cells by assessing all toxicities in organ-based groups during the first year posttreatment. We observed 539 grade ≥2 and 289 grade ≥3 toxicities. Common grade ≥3 toxicities included hematological, metabolic, infectious, and neurological complications, with corresponding 1-year cumulative incidence of 57.7%, 54.8%, 35.4%, and 18.3%, respectively. Patients with impaired performance status had a higher risk of grade ≥3 metabolic complications, whereas elevated lactate dehydrogenase was associated with higher risks of grade ≥3 neurological and pulmonary toxicities. CRS was associated with higher incidence of grade ≥3 metabolic, pulmonary, and neurologic complications. The 1-year nonrelapse mortality and overall survival were 1.7% and 69%, respectively. Only grade ≥3 pulmonary toxicities were associated with an increased mortality risk. In summary, toxicity burdens after CD19 CAR T-cell therapy were high and varied by organ systems. Most toxicities were manageable and were rarely associated with mortality. Our study emphasizes the importance of toxicity assessment, which could serve as a benchmark for further research to reduce symptom burdens and improve tolerability in patients treated with CAR T cells.

scholarly journals Chimeric Antigen Receptor T Cell Exhaustion during Treatment for Hematological Malignancies

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Chunyi Shen ◽  
Zhen Zhang ◽  
Yi Zhang
Keyword(s):  
T Cells ◽  
T Cell ◽  
Chimeric Antigen Receptor ◽  
Hematological Malignancies ◽  
Antigen Receptor ◽  
T Cell Exhaustion ◽  
Cell Exhaustion ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Immunotherapy, especially based on chimeric antigen receptor (CAR) T cells, has achieved prominent success in the treatment of hematological malignancies. However, approximately 30-50% of patients will have disease relapse following remission after receiving CD19-targeting CAR-T cells, with failure of maintaining a long-term effect. Mechanisms underlying CAR-T therapy inefficiency consist of loss or modulation of target antigen and CAR-T cell poor persistence which mostly results from T cell exhaustion. The unique features and restoration strategies of exhausted T cells (Tex) have been well described in solid tumors. However, the overview associated with CAR-T cell exhaustion is relatively rare in hematological malignancies. In this review, we summarize the characteristics, cellular, and molecular mechanisms of Tex cells as well as approaches to reverse CAR-T cell exhaustion in hematological malignancies, providing novel strategies for immunotherapies.

scholarly journals Comparing CAR T-cell toxicity grading systems: application of the ASTCT grading system and implications for management

2020 ◽  
Vol 4 (4) ◽  
pp. 676-686 ◽  
Author(s):  
Martina Pennisi ◽  
Tania Jain ◽  
Bianca D. Santomasso ◽  
Elena Mead ◽  
Kitsada Wudhikarn ◽  
...  
Keyword(s):  
T Cell ◽  
B Cell ◽  
Cellular Therapy ◽  
Lymphoblastic Leukemia ◽  
B Cell Lymphoma ◽  
Grading System ◽  
Immune Effector ◽  
Car T Cell ◽  
Grading Systems ◽  
Car T

Abstract Various grading systems are currently used for chimeric antigen receptor (CAR) T-cell–related toxicity, cytokine release syndrome (CRS), and immune effector cell–associated neurotoxicity syndrome (ICANS). We compared the recently proposed American Society for Transplantation and Cellular Therapy (ASTCT) grading system to other grading scores in 2 populations of adults: patients (n = 53) with B-cell acute lymphoblastic leukemia (B-ALL) treated with 1928z CAR T-cells (clinicaltrials.gov #NCT01044069), and patients (n = 49) with diffuse large B-cell lymphoma (DLBCL) treated with axicabtagene-ciloleucel (axi-cel) or tisagenlecleucel after US Food and Drug Administration approval. According to ASTCT grading, 82% of patients had CRS, 87% in the B-ALL and 77% in the DLBCL groups (axi-cel: 86%, tisagenlecleucel: 54%), whereas 50% of patients experienced ICANS, 55% in the B-ALL and 45% in the DLBCL groups (axi-cel: 55%, tisagenlecleucel: 15%). All grading systems agreed on CRS and ICANS diagnosis in 99% and 91% of cases, respectively. However, when analyzed grade by grade, only 25% and 54% of patients had the same grade in each system for CRS and ICANS, respectively, as different systems score symptoms differently (upgrading or downgrading their severity), leading to inconsistent final grades. Investigation of possible management implications in DLBCL patients showed that different recommendations on tocilizumab and steroids across current guidelines potentially result in either overtreating or delaying treatment. Moreover, because these guidelines are based on single products and different grading systems, they cannot be universally applied. To avoid discrepancies in assessing and managing toxicities of different products, we propose that unified grading be used across clinical trials and in practice and that paired management guidelines with product-specific indications be developed.

scholarly journals Advancing CAR T-Cell Therapy for Solid Tumors: Lessons Learned from Lymphoma Treatment

Cancers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 125 ◽  
Author(s):  
Aleksei Titov ◽  
Aygul Valiullina ◽  
Ekaterina Zmievskaya ◽  
Ekaterina Zaikova ◽  
Alexey Petukhov ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
Solid Tumors ◽  
B Cell Lymphoma ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

Chimeric antigen receptor (CAR) immunotherapy is one of the most promising modern approaches for the treatment of cancer. To date only two CAR T-cell products, Kymriah® and Yescarta®, have been approved by the Food and Drug Administration (FDA) for the treatment of lymphoblastic leukemia and B-cell lymphoma. Administration of CAR T-cells to control solid tumors has long been envisaged as one of the most difficult therapeutic tasks. The first two clinical trials conducted in sarcoma and neuroblastoma patients showed clinical benefits of CAR T-cells, yet multiple obstacles still hold us back from having accessible and efficient therapy. Why did such an effective treatment for relapsed and refractory hematological malignancies demonstrate only relatively modest efficiency in the context of solid tumors? Is it due to the lucky selection of the “magic” CD19 antigen, which might be one of a kind? Or do lymphomas lack the immunosuppressive features of solid tumors? Here we review the existing knowledge in the field of CAR T-cell therapy and address the heterogeneity of solid tumors and their diverse strategies of immunoevasion. We also provide an insight into prospective developments of CAR T-cell technologies against solid tumors.

scholarly journals Sequential Infusion of Anti-CD22 and Anti-CD19 Chimeric Antigen Receptor T Cells for Adult Patients with Refractory/Relapsed B-Cell Acute Lymphoblastic Leukemia

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 846-846
Author(s):  
Liang Huang ◽  
Na Wang ◽  
Chunrui Li ◽  
Yang Cao ◽  
Yi Xiao ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
Lymphoblastic Leukemia ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T ◽  
Antigen Loss

Abstract Clinical trials of second generation chimeric antigen receptor engineered T cells (CAR-T cells) have yielded unprecedented efficacy in refractory/relapsed B-cell acute lymphoblastic leukemia (B-ALL), especially in children and young adult. However, antigen loss relapse has been observed in approximately 14% of patients in anti-CD19 CAR-T cell therapy across institutions, which emerges as a challenge for the long-term disease control of this promising immunotherapy. Recently, CD19/CD20 and CD19/CD22 dual antigen targeting have been proposed to overcome antigen loss relapse after the administration of anti-CD19 CAR-T cells. This strategy may result in enhanced anti-tumor activity, while safety concern regarding the risk of cytokine release syndrome (CRS) due to significant CAR-T cell activation and cytokine release needs to be addressed. Here, we conducted an open-label, single-center and single-arm pilot study of sequential infusion of anti-CD22 and anti-CD19 CAR-T cells. We aimed to evaluate its safety and efficacy in adult patients with refractory or relapsed B-ALL. This trial is registered with ChiCTR, number ChiCTR-OPN-16008526. Between March 2016 and March 2017, 27 patients with refractory or relapsed B-ALL were enrolled in this clinical trial, with a median age of 30±12 years (range, 18-62 years). Thirteen patients (48.1%) had a history of at least two prior relapsed or primary refractory disease. Twenty-six patients received fludarabine and cyclophosphamide before the infusion of CAR-T cells. The median cell dosages of anti-CD22 and anti-CD19 CAR-T cells were 2.44 ± 1.02 × 106 /kg and 1.98 ± 1.05 × 106 /kg, respectively. 24/29 (88.9%) patients achieved CR or Cri, including 7 patients who received prior hematopoietic stem cell transplantation, and 13/27 (48.1%) patients achieved minimal residual disease negative (MRD-) CR accessed by flow cytometry. Sustained remission was achieved with a 6-month overall survival rate of 79% (95% CI, 66-97) and an event-free survival rate of 72% (95% CI, 55-95). 24/29 (88.9%) patients experienced CRS and 6/27 (22.2%) patients had reversible sever CRS (grade 3-4). And 3/27 (11.1%) patients developed neurotoxicity. Multi-color flow cytometry was used to screen and quantitate MRD in blood, bone marrow and cerebrospinal fluid. Antigen escape of CD19 and CD22 was not detected in any relapsed patient post-CAR-T cell therapy. Our results indicated that sequential infusion of third generation Anti-CD22 and Anti-CD19 CAR-T cell therapy is feasible and safe for patients with refractory/relapsed B-ALL. Dual antigen targeting should be a promising approach for overcoming antigen escape relapse, while needs to be further determined in our clinical trial. Disclosures No relevant conflicts of interest to declare.

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