Autologous Chimeric Antigen Receptor T-cell Research Articles

Prognostic impact of corticosteroid and tocilizumab use following chimeric antigen receptor T-cell therapy for multiple myeloma.

Despite being the mainstay of management for cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), there is limited data regarding the impact of tocilizumab (TCZ) and corticosteroids (CCS) on chimeric antigen receptor (CAR) T-cell efficacy in multiple myeloma (MM). The present study aims to evaluate the prognostic impact of these immunosuppressants in recipients of BCMA- or GPRC5D-directed CAR T cells for relapsed/refractory MM. Our retrospective cohort involved patients treated with commercial or investigational autologous CAR T-cell products at a single institution from March 2017-March 2023. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall response rate (ORR), complete response rate (CRR), and overall survival (OS). In total, 101 patients (91% treated with anti-BCMA CAR T cells and 9% treated with anti-GPRC5D CAR T cells) were analyzed. Within 30 days post-infusion, 34% received CCS and 49% received TCZ for CRS/ICANS management. At a median follow-up of 27.4 months, no significant difference in PFS was observed between CCS and non-CCS groups (log-rank p = 0.35) or between TCZ and non-TCZ groups (log-rank p = 0.69). ORR, CRR, and OS were also comparable between evaluated groups. In our multivariable model, administering CCS with/without TCZ for CRS/ICANS management did not independently influence PFS (HR, 0.74; 95% CI, 0.36-1.51). These findings suggest that, among patients with relapsed/refractory MM, the timely and appropriate use of CCS or TCZ for mitigating immune-mediated toxicities does not appear to impact the antitumor activity and long-term outcomes of CAR T-cell therapy.

BCMA/CD47-directed universal CAR-T cells exhibit excellent antitumor activity in multiple myeloma

BackgroundBCMA-directed autologous chimeric antigen receptor T (CAR-T) cells have shown excellent clinical efficacy in relapsed or refractory multiple myeloma (RRMM), however, the current preparation process for autologous CAR-T cells is complicated and costly. Moreover, the upregulation of CD47 expression has been observed in multiple myeloma, and anti-CD47 antibodies have shown remarkable results in clinical trials. Therefore, we focus on the development of BCMA/CD47-directed universal CAR-T (UCAR-T) cells to improve these limitations.MethodsIn this study, we employed phage display technology to screen nanobodies against BCMA and CD47 protein, and determined the characterization of nanobodies. Furthermore, we simultaneously disrupted the endogenous TRAC and B2M genes of T cells using CRISPR/Cas9 system to generate TCR and HLA double knock-out T cells, and developed BCMA/CD47-directed UCAR-T cells and detected the antitumor activity in vitro and in vivo.ResultsWe obtained fourteen and one specific nanobodies against BCMA and CD47 protein from the immunized VHH library, respectively. BCMA/CD47-directed UCAR-T cells exhibited superior CAR expression (89.13-98.03%), and effectively killing primary human MM cells and MM cell lines. BCMA/CD47-directed UCAR-T cells demonstrated excellent antitumor activity against MM and prolonged the survival of tumor-engrafted NCG mice in vivo.ConclusionsThis work demonstrated that BCMA/CD47-directed UCAR-T cells exhibited potent antitumor activity against MM in vitro and in vivo, which provides a potential strategy for the development of a novel “off-the-shelf” cellular immunotherapies for the treatment of multiple myeloma.Graphic

DNT cells mediate resistance to CAR-T cells therapy in a pediatric patient with relapsed and refractory B-ALL.

Chimeric antigen receptor T (CAR-T) cells therapy is a milestone achievement in the immunotherapy of relapsed and refractory (R/R) B cell acute lymphoblastic leukemia (B-ALL). However, some patients treated with CAR-T cells do not achieve complete remission, the mechanisms of which have not been elucidated. In the present study, we report a 9-year-old pediatric patient with refractory B-ALL received a triple infusion of autologous CD19 CAR-T cells therapy after the second relapse. CAR-T cells expanded in the peripheral blood and bone marrow. However, the patient did not achieve complete remission, indicating a lack of response to CAR-T cells therapy. Analysis of etiological factors revealed that the number of CD4 and CD8 double-negative T (DNT) cells was significantly upregulated in the peripheral blood, bone marrow, and autologous CAR-T cells products. In conclusiont,these findings indicate that DNT cells mediated resistance to CAR-T cells therapy in this pediatric patient with R/R B-ALL.

Challenges and Lessons Learned in Autologous Chimeric Antigen Receptor T-Cell Therapy Development from a Statistical Perspective.

Chimeric antigen receptor (CAR) T-cell therapy is a human gene therapy product where T cells from a patient are genetically modified to enable them to recognize desired target antigen(s) more effectively. In recent years, promising antitumor activity has been seen with autologous CAR T cells. Since 2017, six CAR T-cell therapies for the treatment of hematological malignancies have been approved by the Food and Drug Administration (FDA). Despite the rapid progress of CAR T-cell therapies, considerable statistical challenges still exist for this category of products across all phases of clinical development that need to be addressed. These include (but not limited to) dose finding strategy, implementation of the estimand framework, use of real-world data in contextualizing single-arm CAR T trials, analysis of safety data and long-term follow-up studies. This paper is the first step in summarizing and addressing these statistical hurdles based on the development of the six approved CAR T-cell products.

Advancing Autologous CAR T-cell Therapy through Real-Time Patient Health Data Integration: A Simulation-Based Approach

Autologous chimeric antigen receptor (CAR) T-cell therapy presents promising treatment outcomes for various cancers. However, its potential is restrained by unique supply chain challenges, including dynamic patient health conditions and extended turnaround time. These challenges often lead to missed optimal treatment windows, impeding the effective delivery of life-saving treatments. This paper presents SimPAC (Simulation-based decision support for Patient-centric manufacturing of Autologous Cell therapies). SimPAC is designed to model and incorporate real-time patient health conditions into the supply chain decisions of autologous CAR T-cell therapy. SimPAC integrates system dynamics and agent-based simulation techniques, facilitating the adaptation of manufacturing processes and production schedules based on real-time patient health conditions. SimPAC can model various patient disease progressions using parametric functions, non-parametric functions, or tabular data. Additionally, SimPAC offers easy configuration options to model various cell therapy supply chains. We provide two case studies to demonstrate the capabilities of SimPAC and highlight the benefits of patient-centric manufacturing, including improved survival rates and potential economic advantages. However, while the benefits are significant, our study also emphasizes the importance of balancing improved patient outcomes, economic viability, and ethical considerations in the context of personalized medicine. SimPAC can be used to explore applications of this approach to diverse therapeutic contexts and supply chain configurations.

Sequencing of Therapy Matters in the Era of Autologous Chimeric Antigen Receptor T-cell Therapy

Sequencing of Therapy Matters in the Era of Autologous Chimeric Antigen Receptor T-cell Therapy

Abstract CT071: Clinical activity of P-BCMA-ALLO1, a B-cell maturation antigen (BCMA) targeted allogeneic chimeric antigen receptor T-cell (CAR-T) therapy, in relapsed refractory multiple myeloma (RRMM) patients (pts) following progression on prior BCMA targeting therapy

Abstract Introduction: Despite therapeutic advances, multiple myeloma remains incurable. BCMA targeting immunotherapies, such as bispecific T-cell engagers (TCE) and autologous CAR-T provide high response rates, but relapses are common. Autologous CAR-T are logistically challenging due to the need for apheresis, prolonged manufacturing and occasional manufacturing failures. Importantly, pts who have progressed after a prior BCMA targeting immunotherapy are an emerging area of high unmet need. Emerging data indicate that autologous CAR-T have lower clinical activity in pts ho have progressed on TCE. Methods: P-BCMA-ALLO1 is an allogeneic CAR-T therapy manufactured from healthy donor T-cells available “off-the-shelf” and being evaluated in a phase 1 clinical trial (P-BCMA-ALLO1-001) in RRMM pts. This primary objective is to determine the maximum tolerated dose of P-BCMA-ALLO1, and the key secondary objective is to investigate the anti-myeloma activity. The pts must have progressed on a prior proteasome inhibitor, immunomodulatory drug and anti-CD38 monoclonal antibody. The study allows enrollment of pts who have received prior BCMA targeting therapy. The study is exploring escalating P-BCMA-ALLO1 doses and several different lymphodepletion chemotherapy (LD) regimens. Here we report the safety and early efficacy results for the 5 pts who were treated with P-BCMA-ALLO1 after having progressed on BCMA targeting CAR-T, TCE or both. These pts were treated in arms P1 (LD: cyclophosphamide (cy) 500 mg/m2 + fludarabine (flu) 30 mg/m2 X 3 days) or arm P2 (LD: cy 1000 mg/m2 + flu 30 mg/m2 X 3 days) at a P-BCMA-ALLO1 dose of > 2 X 106 to <6 X 106 cells/kg. Results: The median pt age was 62 years and median prior lines of therapy was 10. Three pts were treated in arm P2 and 2 in arm P1. Two pts had received prior teclistamab, 2 had received prior CAR-T and 1 had received prior teclistamab and CAR-T. P-BCMA-ALLO1 was well tolerated with no dose limiting toxicities or graft vs. host disease. Three of the five pts developed cytokine release syndrome (all grade (G) 2) and one developed G2 immune effector cell neurotoxicity syndrome. Three of the five pts (60%) achieved clinical responses with all three achieving the best response of very good partial response. The two non-responders had previously received and failed to achieve clinical response with teclistamab. One pt who had previously received both teclistamab and CAR-T achieved VGPR. Conclusion: In conclusion, P-BCMA-ALLO1 is an allogeneic CAR-T that is available “on-demand” with activity in RRMM pts who have progressed following prior BCMA targeted CAR-T and TCE. We believe this is the first such report of an allogeneic CAR-T showing clinical activity in such a pt population with high unmet need. Enrollment is continuing and updated data will be presented at the meeting. Citation Format: Bhagirathbhai Dholaria, Leyla Shune, Andrew Kin, Katherine McArthur, Jeff D. Eskew, Christopher E. Martin, Sabrina Haag, Joanne McCaigue, Hamid Namini, Sam DePrimo, Stacey Cranert, Julia Coronella, Devon Shedlock, Rajesh Belani. Clinical activity of P-BCMA-ALLO1, a B-cell maturation antigen (BCMA) targeted allogeneic chimeric antigen receptor T-cell (CAR-T) therapy, in relapsed refractory multiple myeloma (RRMM) patients (pts) following progression on prior BCMA targeting therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT071.

Abstract 5241: Generation of allogeneic CAR-T circumvents functional deficits in patient-derived autologous product for glioblastoma

Abstract Glioblastoma (GBM) is the most common malignant primary brain tumor in adults. Despite an aggressive standard of care that includes maximally safe surgical resection, chemo-radiotherapy, median overall survival remains stagnant at 15 months. However, immunotherapeutic strategies have provided an exciting avenue of exploration to meet clinical need. Chimeric antigen receptor T-cell (CAR-T) therapy has shown promising results in liquid malignancies, but clinical trials in GBM targeting various tumor antigens have not shown durable clinical benefit. While this may be attributable to various tumor-intrinsic immune evasion strategies characteristic of GBM, little work has assessed whether the issue is due to the quality of the CAR-T treatment itself. Currently, CAR-Ts for clinical studies are manufactured in an autologous setting wherein T-cells are extracted from patients, engineered ex-vivo, and subsequently re-infused back. However, peripheral T-cells taken from untreated GBM patients have demonstrated qualitative and functional deficits, which may contribute to suboptimal treatment outcomes. Thus, we aimed to establish whether CAR-Ts generated from GBM patients would show reduced efficacy in comparison to healthy donors using our previously validated CD133 CAR-T. In this work, we show that in-spite of no inherent phenotypic differences, patient derived CAR-Ts shows pre-treatment exhaustion and upon preclinical evaluation using an orthotopic xenograft model of human GBM reduced survival advantage in autologous, patient-derived CD133-targeting CAR-T cell products was observed as compared to the controls. Transcriptomic analysis highlighted a decreased panel-wide enrichment in genes related to T cell and lymphocyte activation, lower prevalence of T cells (including Th1 and CD8+) and higher prevalence of exhausted CD8+ cells in T-cells products derived from GBM donors as compared to healthy donors. To overcome the functional and logistical considerations of autologous therapy, we additionally aimed to generate an “off-the-shelf” allogeneic CD133 CAR-T. Using CRISPR gene editing technology, we generated TCR-knockout CAR-T cells with comparable pre-clinical efficacy to our autologous models. In conclusion, this work highlights the need to reassess autologous CAR-T therapy for GBM and considers allogeneic approaches as promising alternatives. By addressing the inherent deficits in patient-derived CAR-Ts, allogeneic CD133 CAR-Ts may offer a more effective and logistically feasible therapeutic option for treating GBM. Citation Format: Muhammad Vaseem Shaikh, Sabra K. Salim, Jeffrey Wei, William T. Maich, Alisha A. Anand, Oliver Young Tang, Minomi K. Subapanditha, Yujin Suk, Manoj Singh, Zahra Alizada, Benjamin Brakel, Vassil Dimitrov, Zoya Tabunshchyk, Kevin Brown, Parvez Vora, Zev Binder, Chitra Venugopal, Jason Moffat, Sheila K. Singh. Generation of allogeneic CAR-T circumvents functional deficits in patient-derived autologous product for glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5241.

Clinical Pharmacology Considerations for the "Off-the-Shelf" Allogeneic Cell Therapies.

Autologous chimeric antigen receptor T-cell (CAR-T) therapies have garnered unprecedented clinical success with multiple regulatory approvals for the treatment of various hematological malignancies. However, there are still several clinical challenges that limit their broad utilization for aggressive disease conditions. To address some of these challenges, allogeneic cell therapies are evaluated as an alternative approach. As compared with autologous products, they offer several advantages, such as a more standardized "off the shelf" product, reduced manufacturing complexity, and no requirement of bridging therapy. As with autologous CAR-T therapies, allogeneic cell therapies also present clinical pharmacology challenges due to their invivo living nature, unique pharmacokinetics or cellular kinetics (CKs), and complex dose-exposure-response relationships that are impacted by various patient- and product-related factors. On top of that, allogeneic cell therapies present additional unique challenges, including attenuated invivo persistence and graft-vs.-host disease risk as compared with autologous counterparts. This review draws comparison between autologous and allogeneic cell therapies, summarizing key engineering aspects unique to allogeneic cell therapy. Clinical pharmacology learnings from emerging clinical data of allogeneic cell therapy programs are also highlighted, with particular emphasis on CK, dose-exposure-response relationship, lymphodepletion regimen, repeat dosing, and patient- and product-related factors that can impact CK and patient outcomes. There are specific unique challenges and opportunities arising from the development of allogeneic cell therapies, especially in optimizing lymphodepletion and establishing a regimen for repeat dosing. This review highlights how clinical pharmacologists are well positioned to help address these challenges by leveraging novel clinical pharmacology and modeling and simulation approaches.

Cryopreserved leukapheresis material can be transferred from controlled rate freezers to ultracold storage at warmer temperatures without affecting downstream CAR-T cell culture performance and in-vitro functionality

Chimeric antigen receptor (CAR) T-cell therapies are increasingly adopted as a commercially available treatment for hematologic and solid tumor cancers. As CAR-T therapies reach more patients globally, the cryopreservation and banking of patients’ leukapheresis materials is becoming imperative to accommodate intra/inter-national shipping logistical delays and provide greater manufacturing flexibility. This study aims to determine the optimal temperature range for transferring cryopreserved leukapheresis materials from two distinct types of controlled rate freezing systems, Liquid Nitrogen (LN2)-based and LN2-free Conduction Cooling-based, to the ultracold LN2 storage freezer (≤−135 °C), and its impact on CAR T-cell production and functionality. Presented findings demonstrate that there is no significant influence on CAR T-cell expansion, differentiation, or downstream in-vitro function when employing a transfer temperature range spanning from −30 °C to −80 °C for the LN2-based controlled rate freezers as well as for conduction cooling controlled rate freezers. Notably, CAR T-cells generated from cryopreserved leukapheresis materials using the conduction cooling controlled rate freezer exhibited suboptimal performance in certain donors at transfer temperatures lower than −60 °C, possibly due to the reduced cooling rate of lower than 1 °C/min and extended dwelling time needed to reach the final temperatures within these systems. This cohort of data suggests that there is a low risk to transfer cryopreserved leukapheresis materials at higher temperatures (between −30 °C and −60 °C) with good functional recovery using either controlled cooling system, and the cryopreserved materials are suitable to use as the starting material for autologous CAR T-cell therapies.

FDA Investigating CAR-Related T-cell Malignancies.

The FDA is investigating reports that BCMA- and CD19-directed autologous chimeric antigen receptor T-cell immunotherapies, which are used to treat a variety of blood cancers, may be causing secondary malignancies. However, the agency and hematologists say the potential benefits of the agents, which have saved thousands of lives, outweigh this risk.

Bridging treatment prior to chimeric antigen receptor T-cell therapy in multiple myeloma.

Autologous patient-derived adoptive T-cell therapies have revolutionized the management of relapsed multiple myeloma (MM). However, the current manufacturing and quality control processes result in lengthy vein-to-vein time, making bridging therapy necessary for most patients. Yet the decision and choice of optimal bridging therapy are complex in the heavily pretreated relapsed MM patient. In this perspective piece, the authors provide their approach and considerations while selecting an optimal bridging regimen before autologous chimeric antigen receptor T-cell therapy.

Venetoclax Pre-Treatment of CLL/SLL Patients Enhances Autologous CAR T-Cells Efficacy

Introduction Venetoclax is an oral targeted therapy drug that is FDA-approved for the treatment of chronic lymphocytic leukemia and small lymphocytic lymphoma (CLL/SLL) in both the frontline and relapsed/refractory (R/R) settings. While Venetoclax's dominant mechanism of action is the inhibition of Bcl-2 and thus, priming malignant CLL/SLL cells for apoptosis, there are emerging data highlighting the effects of Venetoclax on T-cell fitness/function. T-cell populations in CLL/SLL are known to be functionally impaired, in part due to abnormal expansion of T-regulatory cell (Treg) populations that blunt normal anti-tumoral cellular immune responses by CD8 + T-cells, Th1 Helper T-cells, and NK-cells and allows CLL/SLL cells to proliferate. Treg cell frequency has also been shown to directly correlate with CLL/SLL progression, and treatment of CLL/SLL results in lower circulating Treg populations. The unfavorable and generally anti-inflammatory tumoral microenvironment fostered by CLL/SLL cells is a major obstacle to the development of effective chimeric antigen receptor (CAR) T-cell options for this disease, for which there are currently no FDA-approved products despite more than a decade of investigation. Objective: In our current work, we studied the impact of Venetoclax on T-cell composition and function in serially collected specimens from patients with CLL/SLL; and evaluated the function of CAR T-cells manufactured from Venetoclax treated patients. Methods Peripheral blood mononuclear cells (PMBCs) and plasma was collected from CLL/SLL patients (N=5) who were treated with Venetoclax using the standard ramp up dosing-protocol. All procedures were approved by our IRB under BDR 164122. Samples were collected at pre-treatment (baseline) and several post-Venetoclax dosing timepoints (Day +1 day, day +7, and day +30). B-cells were isolated by negative selection using magnetic beads. CLL cells were the B-cells were exposed Venetoclax alone or in combination with several chemotherapy agents. Cell viability was determined by Cell Titer glo after 48hrs of drug exposure. In addition, PBMCs samples were analyzed using multicolor parameter flow cytometry to determine T-cell subsets composition including memory phenotype/stemness and others at each time point. Thorough serum cytokine (IL-15, IL-6, Il-2 and IL-10) analysis was conducted at each time point. Using baseline and 1-week post Venetoclax PBMCs samples, T-cells were activated, and autologous second generation CD19-directed CAR T-cells were manufactured. The efficacy of CARs were then tested at a 1:1 effector to target ratio against Raji and Raji 4RH cells for 24 hours and analyzed for cytotoxicity via flow cytometry. Results As expected Venetoclax was active in all samples tested. In addition, synergistic activity was observed when combined with chemotherapy agents or targeted agents (i.e. BRD-4 inhibitors). Regarding T-cell function, flow cytometry analysis at day +30 of Venetoclax therapy demonstrated that T-helper and T-cytotoxic T-cells displayed less exhaustion markers when compared to pre-Venetoclax samples (Baseline). Of interest, autologous αCD19 CAR T-cells manufactured 1 week following Venetoclax therapy induced higher cytotoxicity against Raji (rituximab chemotherapy sensitive cell lines) or Raji 4RH (rituximab-chemotherapy resistant cell lines) cells when compared to CAR T-cells generated from Venetoclax pre-treatment T-cells. Conclusion Our data suggests that Venetoclax has anti-tumor activities beyond direct CLL cytotoxicity. Venetoclax therapy appears to repair T-cell subsets in CLL patients. Perhaps by decreasing exhaustion markers in CD4/CD8 T-cells, Venetoclax potentiate the cytotoxicity of anti-CD19 CAR T cells against B-cell lymphoma. Further work is needed to fully elucidate the mechanism(s) by which Venetoclax modifies the fitness and function of T-cell subsets. These efforts may guide the development of combination strategies using BH-3 mimetics and T-cell engagers based therapeutic options for patients with CLL/SLL.

Using Real-World Remanufacturing and Recollection Data to Optimize Time-to-Treatment in Patients with out-of-Specification Ciltacabtagene Autoleucel

Ciltacabtagene autoleucel (cilta-cel) is a B-cell maturation antigen (BCMA)-directed genetically modified autologous chimeric antigen receptor-T cell (CAR-T) immunotherapy approved for the treatment of adults with relapsed/refractory multiple myeloma. Manufacturing of cilta-cel can take approximately 4 weeks from receipt of apheresis material until release for cilta-cel infusion. Though manufacturing is a well-controlled biological production process, delays in release can occur when the final product does not meet predetermined release specifications. Such products are referred to as being out-of-specification(s) (OOS). In the United States, OOS CAR-T products may be released for use via an exceptional release process as part of an expanded access clinical trial (NCT05346835). Additional time is needed as the process requires the prescriber's request for release, an internal safety review to assess benefit/risk, and US Food and Drug Administration (FDA) notification and/or approval. Further delays to treatment may occur if a prescriber requests to remanufacture and potentially recollect new apheresis material, attempting to obtain an in-specification product. In some instances, this increased time has resulted in clinically significant disease progression. We reviewed and characterized the experience from discussions with prescribers regarding OOS cilta-cel over the past 18 months. Options presented to the prescriber included: (1) remanufacture using the original apheresis product, (2) recollection of new apheresis material, (3) exceptional release of the OOS cilta-cel, and (4) cancellation of the order. The outcomes for cases of remanufacturing or recollection were analyzed. To date, remanufacturing from the initial apheresis material has been requested in 37% of OOS cases. Of these cases, 60% of remanufacturing attempts resulted in the same or worse outcomes (ie, additional OOS outcomes or worse performance on the original OOS outcomes). Recollection of new apheresis material was requested in 15% of OOS cases, either because of insufficient remaining material or concern about the impact of therapy received prior to collection. Upon recollection, 65% of these attempts resulted in the same or worse outcomes. The reason cilta-cel was determined to be OOS varied. Of remanufacturing attempts for OOS due to a low proportion of CAR+ cells, none were successful in obtaining an in-specification product. Cases where OOS was due to low cell viability were unsuccessfully remanufactured or recollected 71% and 75% of the time, respectively, whereas OOS due to low dose was unsuccessfully remanufactured 95% of the time. On occasion, the second attempt at remanufactured OOS cilta-cel due to low dose has been combined with the OOS cilta-cel generated in the first manufacture to achieve a combined dose that meets or comes close to the specified dose range. Remanufacturing or recollection success rates were increased in cases where the root cause of the OOS was due to something inadvertent that occurred during the manufacturing process. Our findings on remanufacturing and recollection outcomes may inform physician decisions and help optimize time-to-treatment in patients receiving cilta-cel. Additional studies (eg, NCT05347485) are underway to evaluate the safety and efficacy of OOS cilta-cel.

CAR T-Cell Therapy Combined with PD-1 Inhibitors Significantly Improve the Efficacy and Prognosis of r/r DLBCL with TP53 Alterations

More than 40% of patients diagnosed with diffuse large B-cell lymphoma (DLBCL) eventually develop relapsed or refractory (r/r) disease and typically have poor outcomes. Autologous chimeric antigen receptor T-cell therapy (CART) has emerged as a crucial second line treatment option for r/r DLBCL, but 60-70% of patients still relapse or are refractory. Recent research has shed light on the role of TP53 alterations (mutation or deletion) in r/r DLBCL patients who do not respond well to CART cell therapy. The findings in this study will show that the combination of CART with PD-1 inhibitors (ICIs) had a significant impact on the efficacy and prognosis of r/r DLBCL patients with TP53 alterations. This retrospective analysis included adult DLBCL patients who were treated at Shanghai Tongji Hospital of Tongji University with autologous CD19 (N=20) or CD20 (N=2, patient 6 and 7, Fig.1 A) CART-cell therapy between January 1, 2019, and September 30, 2022. All enrolled patients provided their informed consent to participate in the study. The protocol of the study was reviewed and approved by the Institutional Review Board of the National Cancer Institute, ensuring ethical practices were followed. A total of 22 patients with TP53 alterations undergoing CD19-CART therapy were included, of which 2 patients received CD20 CART cell after recurrence of CD19 CART cell therapy. The total dose of CD19 or CD20-CAR T-cell is between 1- 3x10^6/kg. Sintilimab/Tislelizumab was used as PD-1 inhibitors (3 mg/kg in patients weighing <60 kg or 200 mg in patients weighing ≥60 kg) every three weeks within 6 weeks after CAR-T infusion. 1 case had grade 3-4 Cytokine Release Syndrome (CRS) and no case had CART-cell-related encephalopathy syndrome (CRES). In Table 1, the patients are divided into two groups. One group received CART cells combined with PD-1 inhibitors (ICI+), while the other group received CART cells only (ICI-). The median ICIs treatment time after CART infusion was 17 days (IQR 11-38 days). Baseline factors such as age, gender, disease severity, previous treatment history and etc. had no substantial differences between the groups. Treatment regimen and the subsequent response were shown in Fig.1 A and B. Patient 1-9 received ICIs treatment after CART cell therapy, of which 8 cases (88.9%) showed the best objective response rate (ORR) at day 90 after CART infusion (Fig.1B) and 6 cases (66.7%) achieved complete remission (CR). In comparison, among the 13 individuals who were treated with CART alone, only 3 cases (23.1%) showed the best ORR at day 90 after CART infusion and only 1 case (7.7%) achieved complete remission. We found a significant difference between the two treatment groups by performing a Chi-square test (P=0.009). Our results suggest that the addition of PD-1 inhibitors to the CART regimen significantly improves the treatment outcome in patients with TP53 alterations. In Fig.1 C and D, we show that the median progression-free survival (PFS) was NR (not reached) vs. 1.7 months (95% CI:1.0 month-2.3 months) and the median overall survival (OS) was NR vs.10.9 months (95% CI: 3.8 months-18.1 months) in the ICI+ and the ICI- groups. The p-values for PFS and OS was 0.001 (HR=0.18, 95% CI: 0.07-0.47) and 0.003 (HR=0.15, 95% CI: 0.05-0.42) between the two groups. These results suggest that patients in the combination treatment group experienced less disease progression and were more likely to survive longer. Overall, our study demonstrates the potential benefits of combining immunotherapies, specifically CART with PD-1 inhibitors, in the treatment of relapsed or refractory DLBCL patients with TP53 alterations.

Graft-Versus-Host Disease after Anti-CD19 Chimeric Antigen Receptor T-Cell Infusion Post Allogeneic Hematopoietic Cell Transplantation: A Transplant Complications and Paediatric Disease Working Parties EBMT Joint Study

Background Anti-CD19 chimeric antigen receptor T-cells (CART) have been incorporated into the therapeutic landscape of B-acute lymphoblastic leukemia (B-ALL) and B-non-Hodgkin's lymphoma (B-NHL). The manufacturing process of commercially available autologous CART in patients relapsing after allogeneic hematopoietic cell transplant (allo-HCT) might include T-cells of donor origin. In this setting, there is limited data on graft-versus-host disease (GvHD) as an off-target effect in patients treated with CART after allo-HCT. We hereby report on a large, retrospective, EBMT registry-based study on GvHD in patients treated with CART therapy after allo-HCT. Methods Inclusion criteria were B-ALL and B-NHL adult and pediatric allo-HCT patients, treated with a first anti-CD19 CART (axicabtagene ciloleucel [axi-cel] and tisagenlecleucel [tisa-cel]) from 2018 to August 2022. The primary study endpoints were the cumulative incidences (CI) of new acute GvHD (aGvHD) and chronic GvHD (cGvHD). Secondary endpoints were the 1-year GvHD relapse-free survival (GRFS), non-relapse mortality (NRM), and overall survival (OS). Overall data was analyzed in a descriptive manner. Results A total of 257 allo-HCT patients treated with anti-CD19 CART were included. One hundred seventy-two patients (66.9%) were ≥18 years old. Tisa-cel was the therapy of choice in 184 patients (71.6%), whereas axi-cel was used in 73 patients (28.4%). More than half of the cohort (57.6%) underwent allo-HCT from unrelated donors. Notably, 109 patients (46.6%) and 38 patients (15%) had previously develop aGvHD and cGvHD between allo-HCT and CART infusion. Table 1 describes data on baseline patient, allo-HCT and CART characteristics of the whole cohort and of patients developing aGvHD and cGvHD. In total, 3 patients developed new aGvHD and 6 patients developed new cGvHD after CART therapy. The 100-day CI of new aGvHD was 1.6% (95% CI, 0.4-4.2) and the 12-month CI of new cGvHD was 2.8% (95% CI, 1.1-5.7). No GvHD was observed in the pediatric cohort. The median time from allo-HCT to CART infusion was 15.8 months (range, 3.8-220.3) and the median times from CART to the development of aGvHD and cGvHD were respectively 44 days (range, 8-81) and 144 days (range, 5-182). The 1-year GRFS and NRM were 52.1% (95% CI 45.6-59.4) and 4.7% (95% CI 2.5-8.1) respectively (Figure 1). With a median follow up of 18.8 months (95% CI, 16.2-23.7), the 1-year OS was 76.8% (95% CI 71.5-82.4). The most frequent cause of death was disease-related in 56 patients (74.6%). Conclusion Together, in this large cohort including adult and pediatric allo-HCT patients treated with tisa-cel and axi-cel after allo-HCT, these data show that the incidence of both aGvHD and cGvHD is very low. Of note, GvHD was not observed in the pediatric cohort. Furthermore, no excessive NRM was observed compared to previously published methods of treating relapse post allo-HCT, being disease progression a major hurdle to optimal outcomes in this cohort of patients.

A Phase 1 Dose Escalation Trial of Third-Generation CD19-Directed CAR T-Cells Incorporating CD28 and Toll-like Receptor 2 (TLR2) Intracellular Domains for Relapsed or Refractory B-Cell Non-Hodgkin Lymphomas (ENABLE)

Introduction: Chimeric antigen receptor (CAR) T cell therapies directed against CD19 and incorporating either CD28 or 4-1BB intracellular co-stimulatory domains are a standard of care for relapsed or refractory (r/r) B-cell lymphomas. CD19-directed CAR T-cell products employing CD28 co-stimulation yield high response rates, but have been associated with higher rates of immune effector cell-associated neurotoxicity syndrome (ICANS) and severe cytokine release syndrome (CRS) than 4-1BB co-stimulated products. There is a need for CAR T-cell products that combine high efficacy with low toxicity. Toll-like receptor 2 (TLR2) is expressed by T-cells, and its engagement enhances T-cell expansion, modulates cytokine production, and promotes long-lived T-cell memory. In preclinical studies, interposition of an intracellular domain from TLR2 between CD28 and CD3ζ resulted in reduced CAR T-cell production of ICANS-associated cytokines GM-CSF and IFN-γ, while maintaining production of the homeostatic cytokine IL-7. We investigated the safety and efficacy of a novel third generation CD19-directed CAR T-cell product, which combines CD28 and TLR2 co-stimulatory domains ( Figure). Methods: We completed a first-in-human phase 1 dose escalation trial of WZTL-002, comprising autologous 1928T2z CAR T-cells (‘ENABLE’, NCT04049513) for patients with r/r B-cell non-Hodgkin lymphomas (B-NHL). A 3+3 dose escalation design was used, with doses from 5 × 10 4 to 1 × 10 6 viable CAR T-cells/kg body weight. Eligible participants had radiologically assessable disease, satisfactory organ function and no central nervous system (CNS) involvement by lymphoma. Bridging therapy was permitted after leukapheresis and pending CAR T-cell manufacture and release. WZTL-002 CAR T-cells were administered intravenously after 3 days of fludarabine (30mg/m 2/day) and cyclophosphamide (500mg/m 2/day) lymphodepletion. Adverse events (AEs) were graded by CTCAE 5.0 except CRS and ICANS (graded by American Society for Transplantation and Cellular Therapy criteria). Response assessment was by PET/CT at month 3, per Lugano 2014 criteria. Pharmacokinetic analyses were by droplet digital PCR for CAR transgenes in blood mononuclear cells. Results: Of 21 patients treated within the dose escalation trial, median age was 57 years (range 23 - 70); 10 (48%) were female; 4 (19%) Māori. Lymphomas were of large cell histology in 17 (81%, Table). Participants had received a median of 4 prior lines of therapy, including autograft in 11 (52%) and allograft in 1. Product phenotyping showed WZTL-002 CAR T-cells were median 49% CD4 +, 41% CD8 + and 34% CD62L +. As of June 14 2023, all patients had reached the primary follow-up timepoint (3 months after WZTL-002 administration). Grade ≥ 3 AEs occurring in ≥ 10% of recipients were: neutropenia (95%), lymphopenia (57%), hypogammaglobulinemia (57%), anaemia (43%), febrile neutropenia (43%), thrombocytopenia (24%) and tumor pain (19%). Grade 1 - 2 CRS occurred in 13 patients (62%); 6 received tocilizumab and 3 dexamethasone. No CRS of grade ≥ 3, and no ICANS of any grade, occurred. Two grade 4 cytopenia dose limiting toxicities occurred at day 21 (one each at 5 × 10 5 and 1 × 10 6 cells/kg), both resolved to grade 2 by day 90. Maximum tolerated dose was not reached. Responses were seen at all dose levels with complete metabolic response in 11 (52%) at month 3. WZTL-002 CAR T-cells expanded at all dose levels. Among recipients of 0.5 - 1.0 × 10 6 CAR T-cells/kg (n = 12), median peak CAR T-cell level (C max) was 93,950 transgene copies/μg genomic DNA (reached at median day 10) and CAR T-cells persisted in 9 of 11 assessed (82%) at day 90. A recommended phase 2 dose (RP2D) range of 0.5 - 1 × 10 6/kg was selected. Conclusions: In this dose escalation trial of a novel third-generation CD19-directed CAR T-cell product that combines CD28 and TLR2 co-stimulatory domains for r/r B-NHL, we observed no severe CRS, no ICANS of any grade and complete responses at all dose levels. At RP2D, in vivo CAR T-cell expansion was similar to or greater than other CD19-directed products. In conjunction with preclinical findings, this study suggests interposition of a TLR2 domain between CD28 and CD3ζ domains may reduce CAR T-cell-related ICANS risk while retaining efficacy. Enrolment to a dose expansion cohort has commenced and will assess outpatient management and the safety and efficacy of WZTL-002 CAR T-cells manufactured using a closed automated process.

Updated Results of the Phase I BALLI-01 Trial of UCART22 Process 2 (P2), an Anti-CD22 Allogeneic CAR-T Cell Product Manufactured By Cellectis Biologics, in Patients with Relapsed or Refractory (R/R) CD22+ B-Cell Acute Lymphoblastic Leukemia (B-ALL)

Introduction: UCART22 is a genetically modified allogeneic T-cell product manufactured from healthy donor cells. Donor-derived T-cells are transduced using a lentiviral vector to express the anti-CD22 chimeric antigen receptor (CAR) and are further modified using Cellectis' TALEN ® technology to disrupt the T-cell receptor alpha constant ( TRAC) and CD52 genes to minimize risk of graft-vs-host disease (GvHD) and allow use of an anti-CD52 antibody for lymphodepletion (LD). Preliminary results from patients treated with UCART22 manufactured by a CMO (Process 1 (P1)) showed that UCART22 was well-tolerated and meaningful responses were achieved at the highest dose level (DL 3; 5 x 10 6 cells/kg). The fludarabine, cyclophosphamide, and alemtuzumab (FCA) LD regimen was also shown to extend host lymphocyte suppression and improve UCART22 expansion versus fludarabine and cyclophosphamide (FC) alone (Boissel N, et al. EHA 2023). We now report updated results from the BALLI-01 study that includes the first patients treated with UCART22 Process 2 (P2) manufactured by Cellectis Biologics. Methods: The primary endpoints are safety, tolerability, and determining the MTD/RP2D of UCART22. Additional endpoints are anti-leukemic activity and expansion of UCART22. Eligibility criteria include age 15‒70y, B-ALL blast CD22 expression ≥ 70%, and ≥ 2 prior treatment regimens. After FCA (F 30 mg/m 2 × 3d, C 0.5g/m 2 × 3d, A 20 mg/d × 3d) LD regimen, pts received a single infusion of UCART22-P2. In vitro comparability assays suggested that UCART22 P2 was more potent than UCART22 P1, so dose escalation with UCART22 P2 started at DL2 (1 x 10 6 cells/kg) compared to the highest studied dose DL3 (5 x 10 6 cells/kg) with UCART22 P1. Results: As of 01 July 2023, 3 pts were enrolled into the first UCART22 P2 cohort at DL2. Pt 1 is a 17yo female with B-ALL with a hypodiploid karyotype and a germline TP53 mutation whose disease had previously failed to respond to multiagent chemotherapy, blinatumomab (blina), inotuzumab (ino), venetoclax (ven), allogeneic hematopoietic stem cell transplantation (HSCT), and autologous CD19 CAR T-cell therapy (CAR19) x2. Pt 2 is a 68yo female with Ph-negative B-ALL who relapsed with CD19-low disease after multiagent chemotherapy, ino, and blina. Pt 3 is a 27yo male with B-ALL with an ABL2 fusion who had failed multiagent chemotherapy, ino, blina, TKIs, and an experimental autologous CAR19. UCART22 P2 administered after the FCA LD regimen was well tolerated. No DLTs or ICANS were observed. Cytokine release syndrome (CRS) occurred in 2/3 (67%) pts, with one G1 that resolved without treatment and one G2 that resolved after tocilizumab x1. There was one G5 sepsis SAE at D40 considered related to UCART22 P2 and FCA LD in Pt 1. Responses were assessed beginning on D28. Up to FC/FCA-DL3 with 18 pts treated with UCART22 P1, 1 CR, 4 CRi, and 2 morphologic leukemia-free states (MLFS) were observed, with 3 responses occurring out of 6 (50%) patients treated with FCA-DL3 (previously reported, EHA 2023). For UCART22 P2, FCA-DL2, 2/3 pts (67%) responded: Pt 2 achieved an MRD neg CR lasting over 84 days after UCART22 infusion; Pt 1 achieved an MRD negative MLFS up to D40. Pt 3 was refractory to treatment, however this pt received bridging therapy with dasatinib for his ABL2 fusion, and on Day -1, only 47% of the leukemic cells expressed CD22 (down from 88% at screening). UCART22 P2 expansion was observed by flow cytometry in peripheral blood with peak of 79 cells/μl in Pt 1 and 225 cells/μl in Pt 2, both at D11, with predominantly CD8 cells expanding. Inflammatory markers such as ferritin, IFN-γ, TNF-α and IL-6 levels increased more than 3-fold, correlating with UCART22 P2 expansion and CRS. Summary : In vitro comparability studies indicated that UCART22 P2 was more potent than UCART22 P1, and this was suggested clinically, as there was a 67% response rate at DL2 with UCART22 P2 compared to 50% at DL3 with UCART22 P1. Use of UCART22 P2 did not lead to any grade ≥3 CRS, and no DLTs or ICANS was observed. UCART22 P2 expansion was seen in the two responders, which closely correlated with CRS and changes in inflammatory markers. These data support the safety and preliminary efficacy of UCART22 P2 in this poor-risk R/R B-ALL population. The study continues to enroll pts treated with UCART22 P2 at dose level 2i (2.5 x 10 6 cells/kg), and updated data will be presented.

Overall Survival Following First and Second Relapse of DLBCL Treated with Therapies Including Autologous Transplant and CAR-T Cells: Results from the Lion Prospective Observational Registry

Background: Diffuse large B cell lymphoma (DLBCL) is the most common subtype of aggressive non-Hodgkin lymphoma (NHL) and is curable with first-line conventional chemotherapy, but a significant fraction of patients relapse or do not respond to initial therapy. There are a variety of treatments available for relapsed/refractory (RR) disease, including platinum-based salvage chemotherapy often used historically both with or without autologous stem cell transplant, and chimeric antigen receptor T-cell (CAR-T) therapy emerging more recently as a second-line option. We report survival data following 2 nd and 3 rd line therapy for RR DLBCL in a large contemporary prospective cohort. Methods: We selected patients (pts) from the Lymphoma Innovations ORIEN Network (LION) with diffuse large B-cell lymphoma, not otherwise specified and high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements (“double-hit” lymphoma) who had previously received R-CHOP chemotherapy. All patients had signed written consent. Clinical data were abstracted from medical records using standardized protocol. Overall survival was estimated using Kaplan-Meier and defined as time from start of 2 nd (OS2) or 3 rd (OS3) line treatment until death, censoring patients alive at last follow-up. Comparisons of OS were performed using the log-rank test. Results: A total of 328 patients with RR DLBCL who received 2 nd line treatment were included, 177 of whom went on to receive 3 rd line therapy. Baseline characteristics included male sex in 205 pts (65%), stage III/IV disease in 244 pts (81%), and extranodal involvement in 183 pts (63%). Second line treatments included platinum-based salvage chemotherapy both with (99 pts) and without (88 pts) autologous stem cell transplant, rituximab plus gemcitabine and oxaliplatin (30 pts, grouped distinctly from platinum-based salvage chemotherapy), CAR-T therapy (43 pts), polatuzumab vedotin (17 pts), and other classes of treatment (51 pts). Median OS2 for 2 nd line platinum-based salvage chemotherapy with autologous transplant was 110.4 months compared with 50.4 months for platinum-based salvage chemotherapy without transplant. OS2 for platinum-based salvage chemotherapy with autologous transplant was 96.5% (95% CI 90-99) at 12 months, 90.7% (95% CI 81-96) at 24 months, and 79.3% (95% CI 67-88) at 60 months compared with 77.1% (95% CI 66-85) at 12 months, 65.5% (95% CI 52-76) at 24 months, and 38.1% (95% CI 21-55) for platinum-based salvage without transplant. OS2 for rituximab plus gemcitabine and oxaliplatin was 81.7% (95% CI 58-93) at 12 months, still 81.7% (95% CI 58-93) at 24 months, and 70.1% (95% CI 37-88) at 60 months. OS2 for CAR-T cell therapy was 75% (95% CI 50-89) at 12 months and 62.5% (95% CI 36-80) at 24 months, it could not be calculated at 60 months. OS2 for polatuzumab vedotin was 73.5% (95% CI 36-91) at 12 months and could not be calculated at 24 or 60 months. OS3 for platinum-based salvage chemotherapy with autologous transplant was 100% at 12 months and 83.3% (95% CI 27-98) at 24 months compared with 70.7% (95% CI 34-90) at both 12 and 24 months for platinum-based salvage without transplant. OS3 for rituximab plus gemcitabine and oxaliplatin was 75% (95% CI 13-96) at 12 months and 50% (95% CI 6-85). OS3 for CAR-T therapy was 86.3% (95% CI 75-93) at 12 months, 65.8% (95% CI 50-78) and 46.3% (95% CI 22-68) at 60 months. OS3 for polatuzumab vedotin was 53.4% (95% CI 24-76) at 12 months and 40.1% (95% CI 12-67) at 24 months. Conclusions: We observed a statistically significant difference by log-rank in OS2 in patients receiving platinum-based salvage chemotherapy followed by autologous stem cell transplant compared to other therapies in a contemporary cohort of pts with RR DLBCL. This difference is likely driven in part by transplant being a surrogate marker for efficacy of salvage chemotherapy. OS3 was also highest at 12, 24, and 60 months in patients receiving platinum-based salvage chemotherapy followed by transplant. Other therapies including CAR-T cells, polatuzumab vedotin, and rituximab plus gemcitabine and oxaliplatin did not demonstrate significantly different rates of overall survival in the 2 nd or 3 rd line setting.

BMS-986393 (CC-95266), a G Protein-Coupled Receptor Class C Group 5 Member D (GPRC5D)-Targeted Chimeric Antigen Receptor (CAR) T-Cell Therapy for Relapsed/Refractory Multiple Myeloma (RRMM): Updated Results from a Phase 1 Study

Introduction: Despite advances in RRMM therapy, new approaches are needed for patients (pts) that relapse. GPRC5D, an orphan receptor expressed on MM cells with limited expression in other tissues, is a promising therapeutic target for MM. Previously, we presented interim results from the dose escalation and expansion parts of CC-95266-MM-001 (NCT04674813), a phase 1, first-in-human, multicenter, open-label, dose-finding study evaluating BMS-986393 (CC-95266), a GPRC5D-targeted autologous CAR T-cell therapy, in pts with RRMM (Bal S et al. ASH 2022, P364; Bal S et al. EHA 2023, S193). Here, we present updated safety and efficacy data from the study. Methods: Eligible pts received ≥ 3 prior treatment regimens and must have received a proteasome inhibitor, an immunomodulatory agent, an anti-CD38 therapy, and an autologous stem cell transplant (if eligible); prior BCMA-directed and CAR T-cell therapies were allowed. After screening and leukapheresis, pts received bridging therapy, if needed, and underwent lymphodepletion followed by a single infusion of BMS-986393. In dose escalation, BMS-986393 was used at doses of 25, 75, 150, 300, and 450 × 10 6 CAR T cells. In dose expansion, additional pts received 75, 150, 300, or 450 × 10 6 CAR T cells. Safety, tolerability, and determination of maximum tolerated dose and/or recommended phase 2 dose (RP2D) of BMS-986393 were primary objectives; secondary objectives included evaluation of preliminary efficacy. Results: As of May 24, 2023, 70 pts received BMS-986393 at doses of 25 (n = 6), 75 (n = 10), 150 (n = 26), 300 (n = 17), and 450 (n = 11) × 10 6 CAR T cells. 32 pts (46%) had high-risk cytogenetics (del[17p], t[4;14], and/or t[14;16]), 40 (57%) had 1q21amp, and 30 (43%) had extramedullary plasmacytomas; 32 (46%) pts had received prior BCMA-targeted therapy, including BCMA-directed CAR T-cell therapy in 25 (36%) pts. 24 (34%) pts had penta-refractory MM. Grade (G) 3/4 treatment-emergent adverse events (AEs) occurred in 64/70 (91%) pts; the most frequent were neutropenia (69%), anemia (31%), and thrombocytopenia (30%). Any-grade infections occurred in 30 (43%) pts (G 3/4 in 11 [16%] pts). Cytokine release syndrome (CRS) occurred in 59 (84%) pts (G ≥ 3 in 3 [4%] pts, with 1 [1%] G5 event); 3 (4%) pts had hemophagocytic lymphohistiocytosis, all G3. On-target off-tumor treatment-related AEs (TRAEs), all G1/2, included skin (17 [24%]) and nail (11 [16%]) TRAEs and dysgeusia/dysphagia (2 [3%]). Immune effector cell-associated neurotoxicity syndrome (ICANS)-type neurotoxicity occurred in 8 (11%) pts (G3 in 2 [3%] pts). The most frequent non-ICANS neurologic TRAEs were headache (10 [14%]), dizziness (6 [9%]), ataxia (5 [7%]), dysarthria (3 [4%]), neurotoxicity (3 [4%], including events termed cerebellar toxicity in 2 pts), and paresthesia, gait disturbance, and nystagmus (1 pt each [1%]). Aside from headache and paresthesia, incidence of the listed non-ICANS neurologic TRAEs appeared to be dose-related, and reversibility of some events was observed. Overall response rate (ORR) across doses was 86% (55/64) in efficacy-evaluable pts and 75% (21/28) in pts treated with prior BCMA-directed therapies, including CAR T cells. Complete response (CR) rate was 38% (24/64). In pts refractory to prior BCMA-directed therapies, ORR was 85% (11/13), and CR rate was 46% (6/13). Median follow-up for all treated pts was 5.9 mo (range, 0.0-24.0). At the time of data cutoff, 75% of responses (41/55) were ongoing. All 10 pts (100%) with available minimal residual disease (MRD) data and a best overall response of CR were MRD-negative (10 −5 depth) at ≥ month 3. BMS-986393 reduced soluble BCMA levels (indicative of tumor burden reduction) across all dose levels and showed a dose-dependent increase in cellular expansion. Conclusions: In this first-in-human study, BMS-986393 showed a manageable safety profile and deep and durable responses, including MRD negativity, at all tested dose levels, including in pts refractory to prior BCMA-directed therapies. CRS and ICANS-type neurotoxicity were mostly low-grade, with increased G ≥ 3 events at the 300 and 450 × 10 6 CAR T-cell doses. On-target off-tumor TRAEs, all G1/2, occurred in a minority of pts. These data support GPRC5D-directed CAR T-cell therapy with BMS-986393 as a potential treatment in RRMM, irrespective of prior BCMA-directed therapy. Dose expansion is continuing to define the RP2D. Updated data will be presented.