CD19 CAR T Cells Maintain Efficacy in the Allogeneic Environment but Mediate Acute Graft-Versus-Host-Disease Only in the Presence CD19+ Acute Lymphoblastic Leukemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1115-1115
Author(s):  
Elad Jacoby ◽  
Haiying Qin ◽  
Yinmeng Yang ◽  
Christopher Daniel Chien ◽  
Terry J Fry

Abstract A significant portion of patients with relapsed acute lymphoblastic leukemia (ALL) who are eligible for treatment with chimeric-antigen-receptor (CAR) T cells have undergone a previous hematopoietic stem cell transplantation. We and others have previously demonstrated that the allogeneic environment, even in the presence mild graft-versus-host disease (GVHD), severely impairs tumor-directed T-cell immunity. To study the behavior of CAR cells in the allogeneic setting we chose a murine model of minor mismatched allogeneic T-cell depleted bone marrow transplantation (BMT) followed by CAR T (CD19-28-z) cell infusion in recipients bearing a murine B-precursor ALL model (positive for CD19). Importantly, the leukemia persists following myeloablative radiation thus mimicking post-transplant minimal residual disease. Donor-derived, post-transplant injection of CD19 CAR T cells eliminated residual leukemia in the syngeneic as well as the allogeneic settings. CD19 CAR T cells harvested from allogeneic recipients maintained in-vitro ability to produce IFN-gamma and degranulate in the presence of ALL ex vivo, at levels comparable to syngeneic CD19 CAR T cells. However, CAR T cells administered in the allogeneic environment had the potential to mediate severe acute GVHD with early mortality of recipients not typically seen in this minor mismatch model. This occurred across multiple T cell doses capable of clearing leukemia (0.3e6-5e6), in transduced CD19 CAR T cells generated from donors tolerized to allogeneic antigens, and when CD19 CAR T cell infusion was delayed following BMT. In-vivo tracking of transferred cells showed comparable expansion and persistence of the CD19 CAR T cells in the allogeneic and syngeneic environments. However, syngeneic CAR T cells tended to develop later into central memory T cells (CD62L+CD44+), whereas the profile of allogeneic cells was significantly skewed toward effector T cells (CD62L-CD44+). Remarkably, the process of CAR-driven acute GVHD in this minor mismatch model was only seen in the presence of leukemia, indicating a CAR-target interaction influences the induction of GVHD. Indeed, pro-inflammatory cytokines IFN-gamma and IL-6 were elevated only in the presence of both ALL and CAR T cells, whereas TNF alpha levels were undetectable in all instances. We are currently testing whether neutralization of cytokines can prevent GVHD in these models. Altogether, these data demonstrate efficacy of CD19 CAR to clear residual leukemia in an immunocompetent mouse model, and maintain initial cytotoxicity despite the potentially suppressive allogeneic environment. However, we demonstrated potential risks of allogeneic CAR T cells aggravating GVHD in the presence of residual leukemia, likely via cytokine-mediated manner. Clinically, as IL-6 was shown to be significant in cytokine release syndrome, this may represent a murine model to study potential interventions. Disclosures No relevant conflicts of interest to declare.

Blood ◽  
2019 ◽  
Vol 133 (21) ◽  
pp. 2291-2304 ◽  
Author(s):  
Diego Sánchez-Martínez ◽  
Matteo L. Baroni ◽  
Francisco Gutierrez-Agüera ◽  
Heleia Roca-Ho ◽  
Oscar Blanch-Lombarte ◽  
...  

Abstract Relapsed/refractory T-cell acute lymphoblastic leukemia (T-ALL) has a dismal outcome, and no effective targeted immunotherapies for T-ALL exist. The extension of chimeric antigen receptor (CAR) T cells (CARTs) to T-ALL remains challenging because the shared expression of target antigens between CARTs and T-ALL blasts leads to CART fratricide. CD1a is exclusively expressed in cortical T-ALL (coT-ALL), a major subset of T-ALL, and retained at relapse. This article reports that the expression of CD1a is mainly restricted to developing cortical thymocytes, and neither CD34+ progenitors nor T cells express CD1a during ontogeny, confining the risk of on-target/off-tumor toxicity. We thus developed and preclinically validated a CD1a-specific CAR with robust and specific cytotoxicity in vitro and antileukemic activity in vivo in xenograft models of coT-ALL, using both cell lines and coT-ALL patient–derived primary blasts. CD1a-CARTs are fratricide resistant, persist long term in vivo (retaining antileukemic activity in re-challenge experiments), and respond to viral antigens. Our data support the therapeutic and safe use of fratricide-resistant CD1a-CARTs for relapsed/refractory coT-ALL.


Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 19-20
Author(s):  
Yi Wang ◽  
Hui Wang ◽  
Ying Gao ◽  
Ding Zhang ◽  
Yan Zheng ◽  
...  

Introduction: It has been made great clinical progresses in hematological malignancies by chimeric antigen receptor (CAR) T cell therapy which utilizes virus vector for manufacture. However, there're still issues unresolved, for instance, sophisticated virus production process, deadly Cytokine Release Syndrome (CRS) side-effect, and high recurrence rate, which probably limit the availability of CAR-T therapy. Non-viral Genome Targeting CAR-T (nvGT CAR-T) may provide a feasible solution to those unmet needs mentioned above. We used CRISPR-Cas9 and non-viral vector to insert anti-CD19 CAR DNA to a specific genome locus in human T cells, which in theory, produces more moderate CAR-T cells compared with conventional CAR-T cells. The efficacy of anti-CD19 nvGT CAR-T cells had been demonstrated in our previous pre-clinical studies, and in this Phase I clinical trial (ChiCTR2000031942), its safety and efficacy in relapsed/refractory B-Cell Acute Lymphoblastic Leukemia (r/r B-ALL) patients were explored. Objective: The primary objective of this Phase I trial is to assess safety, including evaluation of adverse events (AEs) and AEs of special interest, such as CRS and neurotoxicity. Secondary objective is to evaluate efficacy as measured by the ratio of complete remission (CR). Method: Peripheral blood mononuclear cells were collected from patients or allogeneic donors, then CD3+ T cells were selected and modified by nvGT vector to produce anti-CD19 CAR-T, then administrated to patients with r/r B-ALL. Up to July 2020, twelve patients with r/r B-ALL had been enrolled in this study and 8 patients completed their treatments and entered follow-up period. For 8 patients with follow-up data, the median age was 33 years (range, 13 to 61), and the median number of previous regimens was 5 (range, 2 to 11). The median baseline percentage of bone marrow (BM) blast is 72% (range, 24.5% to 99%). Among those subjects, 2 patients once have been conducted autologous or allogeneic hematopoietic stem cell transplantation (Auto-HSCT or Allo-HSCT), and 2 patients experienced serious infection before CAR-T infusion. No patient has been treated by any other CAR-T therapy before enrollment. Baseline characteristics refer to Table 1. Administering a lymphodepleting chemotherapy regimen of cyclophosphamide 450-750 mg/m2 intravenously and fludarabine 25-45 mg/m2 intravenously on the fifth, fourth, and third day before infusion of anti-CD19 nvGT CAR-T, all patients received an infusion at dose of 0.55-8.21×106/kg (Table 1). Result: Until day 30 post CAR-T cell infusion, 8/8 (100%) cases achieved CR and 7/8 (87.5%) had minimal residual disease (MRD)-negative CR (Table 1). Anti-bacterial and anti-fungal were performed in patients SC-3, SC-4 and SC-5 after CAR-T cell infusion, which seems no influence on efficacy. Patient SC-7 was diagnosed as T-cell Acute Lymphoblastic Leukemia before Allo-HSCT but with recent recurrence of B-ALL, which was MRD-negative CR on day 21 post nvGT CAR-T therapy. Up to July 2020, all cases remain CR status. CRS occurred in all patients (100%) receiving anti-CD19 nvGT CAR-T cell, including 1 patient (12.5%) with grade 3 (Lee grading system1) CRS, two (25%) with grade 2 CRS, and 5 (62.5%) with grade 1 CRS. There were no cases of grade 4 or higher CRS (Table 1). The median time to onset CRS was 9 days (range, 1 to 12 days) and the median duration of CRS was 6 days (range, 2 to 9 days). None developed neurotoxicity. No fatal or life-threatening reactions happened and no Tocilizumab and Corticosteroids administered following CAR-T treatment. Data including body temperature (Figure 1), CAR-positive T cell percentage (Figure 2), Interleukin-6 (IL-6) and Interleukin-8 (IL-8) (Figure 3 and 4), C-reactive Protein (CRP) (Figure 5), Lactate Dehydrogenase (LDH) (Figure 6), and Procalcitonin (PCT) (Figure 7), are in accordance with the trend of CRS. Conclusion: This Phase I clinical trial primarily validates the efficacy of this novel CAR-T therapy, however, it still needs time to prove its durability. Surprisingly, we find that nvGT CAR-T therapy is seemingly superior than viral CAR-T therapy in terms of safety. All subjects which are high-risk patients with high tumor burden had low grade CRS, even a few patients sent home for observation post infusion with limited time of in-patient care. Furthermore, patients could tolerate a higher dose without severe adverse events, which probably bring a better dose-related efficacy. Disclosures No relevant conflicts of interest to declare.


2020 ◽  
Vol 21 (11) ◽  
pp. 3906 ◽  
Author(s):  
Aamir Ahmad ◽  
Shahab Uddin ◽  
Martin Steinhoff

Chimeric Antigen Receptor (CAR)-T cell therapy is an exciting development in the field of cancer immunology, wherein immune T-cells from patients are collected, engineered to create ‘CAR’-T cells, and infused back into the same patient. Currently, two CAR-T-cell-based therapies, Tisagenlecleucel and Axicabtagene ciloleucel, are approved by FDA for the treatment of hematological malignancies, acute lymphoblastic leukemia and large B-cell lymphomas. Their approval has been a culmination of several phase I and II clinical studies, which are the subject of discussion in this review article. Over the years, CAR-T cells have evolved to be significantly more persistent in patients’ blood, resulting in a much-improved clinical response and disease remission. This is particularly significant given that the target patient populations of these therapies are those with relapsed and refractory disease who have often progressed on multiple therapies. Despite the promising clinical results, there are still several challenges that need to be addressed. Of particular note are the associated toxicities exemplified by cytokine release syndrome (CRS) and the neurotoxicity. CRS has been addressed by an FDA-approved therapy of its own—tocilizumab. This article focuses on the progress related to CAR-T therapy: the pertinent clinical studies and their major findings, their associated adverse effects, and future perspective.


Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2126-2126 ◽  
Author(s):  
Shuangyou Liu ◽  
Biping Deng ◽  
Yuehui Lin ◽  
Zhichao Yin ◽  
Jing Pan ◽  
...  

Abstract With traditional therapies, the prognosis of relapsed acute lymphoblastic leukemia (ALL) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is extremely poor. Chimeric antigen receptor (CAR) T cell therapy targeting at CD19 has demonstrated a significant efficacy on refractory/relapsed (r/r) B-ALL, but single-target CART could not maintain a long-term remission. Recently, CD22-CART has also shown an exciting result in r/r B-ALL. Here we sequentially applied CD19- and CD22-specific CART cells to treat relapsed B-ALL post-HSCT and observed the therapeutic effect. From June 30,2017 through May 31,2018, twenty-four B-ALL patients (pts) relapsing after allo-HSCT with both antigens CD19 and CD22 expression on blasts were enrolled, the median age was 24 (2.3-55) years. Seventeen pts had hematologic relapse, 6 with both bone marrow and extramedullary (EM) involvements and 1 with EM disease (EMD) only. Fourteen pts had failed to previous therapies including chemotherapy, donor lymphocyte infusion, interferon and even murinized CD19-CART in other hospitals. Recipient-derived donor T cells were collected for producing CAR-T cells, which were transfected by a lentiviral vector encoding the CAR composed of CD3ζ and 4-1BB. Eighteen pts were initially infused with murinized CD19-CART, then humanized CD22-CART; while 6 pts (5 failed to prior murinized CD19-CART and 1 had bright CD22-expression) were initially infused with humanized CD22-CART, then humanized CD19-CART. The time interval between two infusions was 1.5-6 months based on patients' clinical conditions. The average dose of infused CAR T cells was 1.4×105/kg (0.4-9.2×105/kg) for CD19 and 1.9×105/kg (0.55-6.6×105/kg) for CD22. All patients received fludarabine with or without cyclophosphamide prior to each infusion, some pts accepted additional chemo drugs to reduce the disease burden. Treatment effects were evaluated on day 30 and then monthly after each CART, minimal residual disease (MRD) was detected by flow cytometry (FCM) and quantitative PCR for fusion genes, EMD was examined by PET-CT, CT or MRI. Sixteen patients finished sequential CD19- and CD22-CART therapies. Three cases could not undergo the second round of CART infusion (1 died, 1 gave up and 1 developed extensive chronic graft-versus-host disease (GVHD)). The rest of 5 pts are waiting for the second CART. After first T-cell infusion, 20/24 (83.3%) pts achieved complete remission (CR) or CR with incomplete count recovery (CRi), MRD-negative was 100% in CR or CRi pts, 3 (12.5%) cases with multiple EMD obtained partial remission (PR), and 1 (4.2%) died of severe cytokine release syndrome (CRS) and severe acute hepatic GVHD. Sixteen patients (15 CR and 1 PR) underwent the second CART therapy. Before second infusion, 3/15 pts in CR became MRD+ and others remained MRD-. On day 30 post-infusion, 1 of 3 MRD+ pts turned to MRD-, 1 maintained MRD+ ( BCR/ABL+) and 1 had no response then hematologic relapse later. The PR patient still had not obtained CR and then disease progressed. As of 31 May 2018, at a median follow-up of 6.5 (4-10) months, among 16 pts who received sequential CD-19 and CD-22 CART therapies, 1 had disease progression, 2 presented with hematological relapse and 2 with BCR/ABL+ only, the overall survival (OS) rate was 100% (16/16), disease-free survival (DFS) was 81.3% (13/16) and MRD-free survival was 68.8% (11/16). CRS occurred in 91.7% (22/24) pts in the first round of T-cell infusion, most of them were mild-moderate (grade I-II), merely 2 pts experienced severe CRS (grade III-IV). The second CART only caused grade I or no CRS since the leukemia burden was very low. GVHD induced by CART therapy was a major adverse event in these post-HSCT patients. After the first CART, 7/24 (29.2%) pts experienced GVHD, of them, 4 presented with mild skin GVHD, 2 with severe hepatic GVHD (1 recovered and 1 died), and 1 developed extensive chronic GVHD. No severe GVHD occurred in the second infusion. Our preliminary clinical study showed that for B-ALL patients who relapsed after allo-HSCT, single CD19- or CD22- CART infusion resulted in a high CR rate of 83.3%, sequentially combined CD19- and CD22-CART therapies significantly improved treatment outcome with the rate of OS, DFS and MRD-free survival being 100%, 81.3% and 68.8%, respectively, at a median follow-up of 6.5 months. The effect of CART on multiple EMD was not good and CART induced GVHD needs to be cautious. Disclosures No relevant conflicts of interest to declare.


Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2806-2806 ◽  
Author(s):  
Yinmeng Yang ◽  
Mark Eric Kohler ◽  
Terry J Fry

Abstract Tremendous progress has been achieved employing immunotherapy for B cell acute lymphoblastic leukemia (ALL), a leading cause of death in children from cancer. Recent trials using chimeric antigen receptor T cells (CART) targeting the B cell restricted antigen, CD19, that utilize the autologous transfer of patients' T cells, have demonstrated remarkable remission rates of 80% against relapsed or refractory ALL. Despite initial clearance of tumor, relapse with CD19 antigen loss ALL and with CD19 expressing ALL can occur. Attempts at retreatment of patients who have received CD19 CAR T cell therapy suggests that most patients will not respond to a second infusion of CD19 CAR T cells. It has been proposed that failure to respond to a second infusion of CAR T cells may be due to immunogenicity of the foreign CAR protein and elimination of CAR T cells due to immunological targeting. To evaluate the mechanism of retreatment failure in the setting of persistent antigen, we utilized a murine second-generation anti-CD19 scfv/CD28/CD3ζ CAR transduced into mouse CD8 and CD4 polyclonal cells and tested against murine pre-B ALL in a syngeneic system. To investigate the issue of immunogenicity against CAR constructs, we immunized the mice with irradiated CAR T cells prior to CAR treatment to allow for anti-CAR T cell immunity. Following immunization, we inoculated the mice with leukemia on day 0 and treated the mice with 1 x 106 CAR T cells on day 4. CAR treatment was able to clear leukemia and CAR T cell-reactive antibodies were not detected in the serum of the mice, suggesting that a mechanism other than classic host mediated immune rejection of CAR T cells may underlie CAR T cell retreatment failure. To further model the failure of CAR T cell retreatment, we evaluated the ability of a second CAR T cell infusion to eliminate a second leukemic challenge. Leukemia bearing mice were treated with a curative dose of CD19 CAR T cells post lymphodepleting regimen. 30 days after clearance of the primary leukemic challenge, the mice were rechallenged with leukemia and subsequently treated with mock T cells or CD19 CAR T cells. Mice treated with CAR T cells followed by retreatment with mock T cells demonstrated persistence of CAR T cells from the first treatment, which were able to expand and clear the second leukemia challenge. In mice treated with a second dose of CAR T cells, CAR T cells from the second infusion briefly expanded 10 days post infusion, but could not be detected at day 20 post infusion. In contrast, CAR T cells from the initial infusion were still detectable at both time points. These results demonstrate that CAR T cells are able to persist, and, in a model of leukemic relapse, are able to expand and clear leukemia. However, CAR T cells infused into mice with CAR T cells persisting after a prior infusion fail to persist and quickly contract without evidence of host immune rejection of CAR T cells. Our data suggests that the inability to successfully retreat CD19+ relapsed leukemia with subsequent doses of CAR T cells may also involve mechanisms beyond immune recognition and clearance of CAR T cells. Disclosures No relevant conflicts of interest to declare.


2019 ◽  
Vol 13 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Hildegard T. Greinix

SummaryChimeric antigen receptor (CAR) T cells are genetically engineered cells containing fusion proteins combining an extracellular epitope-specific binding domain, a transmembrane and signaling domains of the T cell receptor. The CD19-CAR T cell product tisagenlecleucel has been approved by the US Food and Drug Administration and the European Medicines Agency for therapy of children and young adults under 25 years with relapsed/refractory B‑cell acute lymphoblastic leukemia (ALL) due to a high overall response rate of 81% at 3 months after therapy. The rates of event-free and overall survival were 50 and 76% at 12 months. Despite the high initial response rate with CD19-CAR‑T cells in B‑ALL, relapses occur in a significant fraction of patients. Current strategies to improve CAR‑T cell efficacy focus on improved persistence of CAR‑T cells in vivo, use of multispecific CARs to overcome immune escape and new CAR designs. The approved CAR‑T cell products are from autologous T cells generated on a custom-made basis with an inherent risk of production failure. For large scale clinical applications, universal CAR‑T cells serving as “off-the-shelf” agents would be of advantage. During recent years CAR‑T cells have been frequently used for bridging to allogeneic hematopoietic stem cell transplantation (HSCT) in patients with relapsed/refractory B‑ALL since we currently are not able to distinguish those CAR‑T cell induced CRs that will persist without further therapy from those that are likely to be short-lived. CAR‑T cells are clearly of benefit for treatment following relapse after allogeneic HSCT. Future improvements in CAR‑T cell constructs may allow longer term remissions without additional HSCT.


2016 ◽  
Vol 34 (10) ◽  
pp. 1112-1121 ◽  
Author(s):  
Jennifer N. Brudno ◽  
Robert P.T. Somerville ◽  
Victoria Shi ◽  
Jeremy J. Rose ◽  
David C. Halverson ◽  
...  

Purpose Progressive malignancy is the leading cause of death after allogeneic hematopoietic stem-cell transplantation (alloHSCT). After alloHSCT, B-cell malignancies often are treated with unmanipulated donor lymphocyte infusions (DLIs) from the transplant donor. DLIs frequently are not effective at eradicating malignancy and often cause graft-versus-host disease, a potentially lethal immune response against normal recipient tissues. Methods We conducted a clinical trial of allogeneic T cells genetically engineered to express a chimeric antigen receptor (CAR) targeting the B-cell antigen CD19. Patients with B-cell malignancies that had progressed after alloHSCT received a single infusion of CAR T cells. No chemotherapy or other therapies were administered. The T cells were obtained from each recipient’s alloHSCT donor. Results Eight of 20 treated patients obtained remission, which included six complete remissions (CRs) and two partial remissions. The response rate was highest for acute lymphoblastic leukemia, with four of five patients obtaining minimal residual disease–negative CR. Responses also occurred in chronic lymphocytic leukemia and lymphoma. The longest ongoing CR was more than 30 months in a patient with chronic lymphocytic leukemia. New-onset acute graft-versus-host disease after CAR T-cell infusion developed in none of the patients. Toxicities included fever, tachycardia, and hypotension. Peak blood CAR T-cell levels were higher in patients who obtained remissions than in those who did not. Programmed cell death protein-1 expression was significantly elevated on CAR T cells after infusion. Presence of blood B cells before CAR T-cell infusion was associated with higher postinfusion CAR T-cell levels. Conclusion Allogeneic anti-CD19 CAR T cells can effectively treat B-cell malignancies that progress after alloHSCT. The findings point toward a future when antigen-specific T-cell therapies will play a central role in alloHSCT.


2021 ◽  
pp. JCO.21.00389
Author(s):  
Jing Pan ◽  
Yue Tan ◽  
Guoling Wang ◽  
Biping Deng ◽  
Zhuojun Ling ◽  
...  

PURPOSE Patients with relapsed or refractory T-cell acute lymphoblastic leukemia (r/r T-ALL) have few options and poor prognosis. The aim was to assess donor-derived anti-CD7 chimeric antigen receptor (CAR) T-cell safety and efficacy in patients with r/r T-ALL. METHODS In this single-center, phase I trial, we administered anti-CD7 CAR T cells, manufactured from either previous stem-cell transplantation donors or new donors, to patients with r/r T-ALL, in single infusions at doses of 5 × 105 or 1 × 106 (±30%) cells per kilogram of body weight. The primary end point was safety with efficacy secondary. RESULTS Twenty participants received infusions. Adverse events including cytokine release syndrome grade 1-2 occurred in 90% (n = 18) and grade 3-4 in 10% (n = 2), cytopenia grade 3-4 in 100% (n = 20), neurotoxicity grade 1-2 in 15% (n = 3), graft-versus-host disease grade 1-2 in 60% (n = 12), and viral activation grade 1-2 in 20% (n = 4). All adverse events were reversible, except in one patient who died through pulmonary hemorrhage related to fungal pneumonia, which occurred at 5.5 months, postinfusion. Ninety percent (n = 18) achieved complete remission with seven patients proceeding to stem-cell transplantation. At a median follow-up of 6.3 months (range 4.0-9.2), 15 remained in remission. CAR T cells were still detectable in five of five patients assessed in month 6, postinfusion. Although patients' CD7-positive normal T cells were depleted, CD7-negative T cells expanded and likely alleviated treatment-related T-cell immunodeficiency. CONCLUSION Among 20 patients with r/r T-ALL enrolled in this trial, donor-derived CD7 CAR T cells exhibited efficient expansion and achieved a high complete remission rate with manageable safety profile. A multicenter, phase II trial of donor-derived CD7 CAR T cells is in progress ( NCT04689659 ).


2021 ◽  
Vol 20 (2) ◽  
pp. 30-38
Author(s):  
O. V. Aleinikova ◽  
A. A. Migas ◽  
E. A. Stolyarova ◽  
A. V. Punko ◽  
L. V. Movchan ◽  
...  

The results of treatment of recurrent/refractory acute lymphoblastic leukemia (ALL) with both standard and high-dose chemotherapy are unsatisfactory and require the development of new therapeutic options. The use of immunotherapy approaches opens up new perspectives for patients whose cytotoxic chemotherapy was ineffctive or intolerable. This article describes the experience of using CD19 CAR-T cells manufactured at the Republican Scientifi and Practical Center for Pediatric Oncology, Hematology and Immunology after lymphodepletion with fldarabine and cyclophosphamide in two patients over 18 years of age with refractory relapse of ALL. Other possibilities of conservative treatment for these patients have been exhausted. The study was approved by the Independent Ethics Committee and the Scientifi Council of the Belarusian Research Center for Pediatric Oncology, Hematology and Immunology (Republic of Belarus). The chimeric 2nd generation receptor was constructed from the anti-CD19 scFv antibody fragment, the CD28 transmembrane domain, signaling domains of the 4-1BB and CD3z proteins, and transduced into T-lymphocytes as part of the pWPXL lentiviral vector. The cell product was obtained by separation and separate processing of CD4 and CD8 lymphocytes in the presence of IL-7 and IL-15. The subpopulation composition of the resulting CAR-T cell product and the expression of immune checkpoints were assessed. The results obtained indicate a high antileukemic activity of the obtained CAR-T cells. Monitoring of CAR-T cells' persistence, the level of minimal residual disease, and the spectrum of inflmmatory cytokines in the blood was performed. Both patients responded to CAR-T therapy by lowering their blast cell levels. Treatment was accompanied by a cytokine release syndrome controlled by a recombinant monoclonal antibody to the human IL-6 receptor, tocilizumab. The developed and replicated laboratory-derived CAR-T cell technology can be used to treat patients with severe relapsed/refractory B-line ALL as rescue therapy and provide additional chances for their cure.


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