Autologous CAR Research Articles

State of the Art on CAR T-Cell Therapies for Onco-Haematological Disorders and Other Conditions

The use of chimeric antigen receptors (CAR T-cells) for the treatment of patients with malignant haematological diseases has become a well-established application for conditions such as refractory or relapsed B-cell acute lymphoblastic leukaemia (B-ALL), B-cell lymphomas (BCL), and multiple myeloma (MM). Nearly 35,000 patients have received autologous CAR T-cells for the treatment of these conditions only in the USA. Since their approval by the Food and Drug Administration (FDA) in 2017, over 1200 clinical trials have been initiated globally and there are at least 10 different CAR T-cells with approval by different regulatory agencies around the globe. In the USA, the FDA has approved six commercial CAR T-cells that are widely distributed worldwide. At the time of writing, several clinical trials have been performed in patients with solid tumours such as glioblastoma, renal and pancreatic cancer, as well as in patients with autoimmune conditions such as systemic lupus erythematosus (SLE), idiopathic inflammatory myositis (IIM), and systemic sclerosis (SS). There are also several studies showing the potential benefit of CAR T-cells for other non-malignant diseases such as asthma and even fungal infections. In this review, without pretending to cover all current areas of treatments with CAR T-cells, we offer a brief summary of some of the most relevant aspects of the use of CAR T-cells for some of these conditions.

"Off-The-Shelf" allogeneic chimeric antigen receptor T-cell therapy for B-cell malignancies: current clinical evidence and challenges.

Chimeric antigen receptor T-cell therapy (CAR T) has revolutionized the treatment landscape for hematologic malignancies, notably B-cell non-Hodgkin lymphoma (B-NHL) and B-cell acute lymphoblastic leukemia (B-ALL). While autologous CAR T products have shown remarkable efficacy, their complex logistics, lengthy manufacturing process, and high costs impede widespread accessibility and pose therapeutic challenge especially for patients in rapid need for therapy. "Off-the-shelf" allogeneic CAR T-cell therapy (alloCAR T) has emerged as a promising alternative therapy, albeit experimental to date. AlloCARTs are derived from healthy donors, manufactured by batches and stored, making them available off-the-shelf which lowers financial burden. Various gene editing techniques have been employed to mitigate graft-versus-host disease (GVHD) and host-versus-graft (HvG) to enhance alloCAR T persistence. In this review, we summarize available manufacturing techniques, current evidence, and discuss challenges faced with the use of alloCAR Ts.

Analysis of polyfunctionality for enhanced BAFF-R CAR T-cell therapy for hematologic malignancies

AbstractChimeric antigen receptor (CAR) T-cell therapy has emerged as a promising immunotherapeutic strategy for eradicating human cancers. Their therapeutic success and durability of clinical responses hinges, in large part, on their functional capacity, including the ability of these engineered cells to simultaneously expand and persist after infusion into patients. CD19 CAR T-cell polyfunctionality, assessing the simultaneous functions of cytokine production, proliferation, and cytotoxicity has been reported to correlate with clinical outcomes. Assay optimization is potentially limited by the heterogeneous nature of CAR T-cell infusion products and target specificity. We optimized a single-cell platform for polyfunctionality using CAR T-cell products manufactured from healthy donors, engineered against a novel target, B-cell–activating factor receptor (BAFF-R) and validated the protocol using CD19 CAR T cells. We observed distinct qualitative differences between BAFF-R and CD19 CAR T cells relative to the proportions of stimulatory vs effector cytokines, based on target antigen density, and, generally, CD19 CAR T cells exhibited lower indices of polyfunctionality. Finally, we applied our assay to the autologous BAFF-R CAR T-cell product generated from the first patient with non-Hodgkin lymphoma treated in an ongoing clinical trial who had progressed after prior CD19 CAR T-cell therapy. We observed robust indicators of polyfunctionality, which correlated with successful CAR T-cell expansion after infusion and achievement of durable complete remission ongoing after 18 months. The precise identification of factors determining the role of BAFF-R CAR T-cell fitness in toxicity and clinical outcome will require the application of this robust assay in the analysis of additional treated patients. This trial was registered at www.ClinicalTrials.gov as #NCT05370430.

Phase 2 open label, multicenter study evaluating CRG-022, a CD22-directed autologous CAR T-cell therapy, in patients (pts) with relapsed/refractory (R/R) large B-cell lymphoma (LBCL) after CD19-directed CAR T-cell therapy.

TPS7085 Background: Autologous (auto) CD19-directed CAR T-cell therapy can induce long-term remissions for pts with R/R LBCL but approximately 60% will experience disease progression resulting in poor outcomes (Neelapu, 2023; Zurko, 2023). CRG-022 is a novel CAR T-cell product targeting CD22, a common B-cell antigen widely expressed in LBCL. Key features of CRG-022 include a fully human scFv derived from the m971 monoclonal antibody and 4-1BB/CD3z intracellular signaling domains (Singh, 2021). This CD22 CAR construct was developed at the National Cancer Institute and was investigated in phase (ph) 1 studies of pediatric/young adult pts with R/R CD22+ malignancies (Shah, 2020; NCT02315612) and at Stanford University in adults with R/R LBCL (Baird, 2021; NCT04088890) primarily in pts who received prior CD19-directed CAR-T therapy. The Stanford ph 1b study reported an overall response rate (ORR) and complete response rates of 66% and 52%, respectively in 29 pts treated at the recommended Phase 2 dose (RP2D) of 1x106 CAR+ T cells/kg (Frank, 2023). After a median follow-up of 27.3 months, the median overall survival had not been reached at the RP2D (Su, 2023). At the RP2D, no grade >3 cytokine release syndrome (CRS), immune-effector cell associated neurotoxicity syndrome (ICANS), or immune effector cell associated hemophagocytic lymphohistiocytosis-like syndrome (IEC-HS) occurred; two pts (7%) developed grade 2 IEC-HS (Su, 2023; Srinagesh, 2023). Based on these notable results, this potentially pivotal ph 2 trial has been initiated. Methods: This Phase 2 study will evaluate the safety/efficacy of CRG-022 at 1x106 CAR+ T cells/kg in pts with R/R LBCL whose disease has progressed after CD19-directed CAR T-cell therapy. The primary endpoint is ORR according to Lugano response criteria (Cheson, 2014) by blinded independent review. Adverse events (AEs) are graded per CTCAE v5 except with CRS, ICANS, and IEC-HS graded per ASTCT guidelines. Pts with diffuse large B-cell lymphoma (DLBCL), high grade B-cell lymphoma, DLBCL transformed from follicular or marginal zone lymphoma, follicular large B-cell lymphoma (FLBL)/FL Grade 3B, and primary mediastinal B-cell lymphoma are eligible. Other eligibility criteria include adequate hematologic and organ function, and no prior allogeneic stem cell transplant. Pts with prior treatment to both a CD19-directed auto CAR-T and a bispecific T-cell engaging antibody are also eligible within a separate cohort. Lymphodepletion with fludarabine 30 mg/m2/day and cyclophosphamide 500 mg/m2/day for 3 days will be administered ahead of a single infusion of CRG-022. The study is designed to enroll approximately 123 pts. Study enrollment commenced in the US in August 2023, with 9 pt infused as of 08 JAN 2024. Clinical trial information: NCT05972720 .

Generating universal anti-CD19 CAR T cells with a defined memory phenotype by CRISPR/Cas9 editing and safety evaluation of the transcriptome.

Chimeric antigen receptor-expressing T cells (CAR T cells) have revolutionized cancer treatment, particularly in B cell malignancies. However, the use of autologous T cells for CAR T therapy presents several limitations, including high costs, variable efficacy, and adverse effects linked to cell phenotype. To overcome these challenges, we developed a strategy to generate universal and safe anti-CD19 CAR T cells with a defined memory phenotype. Our approach utilizes CRISPR/Cas9 technology to target and eliminate the B2M and TRAC genes, reducing graft-versus-host and host-versus-graft responses. Additionally, we selected less differentiated T cells to improve the stability and persistence of the universal CAR T cells. The safety of this method was assessed using our CRISPRroots transcriptome analysis pipeline, which ensures successful gene knockout and the absence of unintended off-target effects on gene expression or transcriptome sequence. In vitro experiments demonstrated the successful generation of functional universal CAR T cells. These cells exhibited potent lytic activity against tumor cells and a reduced cytokine secretion profile. The CRISPRroots analysis confirmed effective gene knockout and no unintended off-target effects, validating it as a pioneering tool for on/off-target and transcriptome analysis in genome editing experiments. Our findings establish a robust pipeline for manufacturing safe, universal CAR T cells with a favorable memory phenotype. This approach has the potential to address the current limitations of autologous CAR T cell therapy, offering a more stable and persistent treatment option with reduced adverse effects. The use of CRISPRroots enhances the reliability and safety of gene editing in the development of CAR T cell therapies. We have developed a potent and reliable method for producing universal CAR T cells with a defined memory phenotype, demonstrating both efficacy and safety in vitro. This innovative approach could significantly improve the therapeutic landscape for patients with B cell malignancies.

Outcomes of patients aged ≥26 years with relapsed or refractory B-cell acute lymphoblastic leukemia in ZUMA-3 and historical trials

Brexucabtagene autoleucel (brexu-cel) is an autologous anti-CD19 CAR T-cell therapy approved in the USA and European Union (EU) for adults with relapsed or refractory B-cell acute lymphoblastic leukemia (R/R B-ALL; aged ≥26 years in EU). Here, outcomes for patients with R/R B-ALL aged ≥26 years in ZUMA-3 treated with brexu-cel were compared with historical standard-of-care (SOC) therapy. After median follow-up of 26.8 months, the overall complete remission (CR) rate among patients treated with brexu-cel in Phase 2 (N = 43) was 72% and median overall survival (OS) was 25.4 months (95% CI, 15.9-NE). Median OS was improved in Phase 2 patients versus matched historical SOC-treated patients. Compared with aggregate historical trial data, Phase 1 and 2 patients had improved OS versus blinatumomab, inotuzumab, and chemotherapy in a matching-adjusted indirect comparison (MAIC) study. These data demonstrate clinical benefit of brexu-cel relative to SOC in patients ≥26 years with R/R B-ALL.

CAR T cells outperform CAR NK cells in CAR-mediated effector functions in head-to-head comparison

BackgroundCAR NK cells as vehicles for engineered “off-the-shelf” cellular cancer immunotherapy have attracted significant interest. Nonetheless, a comprehensive comparative assessment of the anticancer activity of CAR T cells and CAR NK cells carrying approved benchmark anti-CD19 CAR constructs is missing. Here, we report a direct head-to-head comparison of CD19-directed human T and NK cells.MethodsWe generated CAR T and CAR NK cells derived from healthy donor PBMC by retroviral transduction with the same benchmark second-generation anti-CD19 CAR construct, FMC63.28z. We investigated IFN-γ secretion and direct cytotoxicity in vitro against various CD19+ cancer cell lines as well as in autologous versus allogeneic settings. Furthermore, we have assessed anticancer activity of CAR T and CAR NK cells in vivo using a xenograft lymphoma model in an autologous versus allogeneic setting and a leukemia model.ResultsOur main findings are a drastically reduced capacity for CAR-mediated IFN-γ production and lower CAR-mediated cytotoxicity of CAR NK cells relative to CAR T cells in vitro. Consistent with these in vitro findings, we report superior anticancer activity of autologous CAR T cells compared with allogeneic CAR NK cells in vivo.ConclusionsCAR T cells had significantly higher CAR-mediated effector functions than CAR NK cells in vitro against several cancer cell lines and autologous CAR T cells outperformed allogeneic CAR NK cells both in vitro and in vivo. CAR NK cells will likely benefit from further engineering to enhance anticancer activity to ultimately fulfill the promise of an effective off-the-shelf product.

Advancing autologous CAR T-cell therapy through real-time patient health data integration: a simulation-based approach

Autologous chimeric antigen receptor 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 article 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 chimeric antigen receptor 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, nonparametric 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.

Abstract PO5-19-03: 1st-in-human CAR T targets MUC1 transmembrane cleavage product

Abstract Background: huMNC2-CAR44 and huMNC2-CAR22 are autologous CAR T cell therapies under study in an ongoing 1st-in-human trial for metastatic breast cancers (NCT04020575), being performed at City of Hope. Both CARs are targeted to the tumor by an antibody, huMNC2, that recognizes a cryptic binding site on MUC1*, which is the transmembrane cleavage product of MUC1. The antibody binds to an epitope that is only unmasked when MUC1 is cleaved to MUC1* by enzymes in the tumor microenvironment. huMNC2 strongly reacts with over 90% of breast cancers. No therapeutic that targets MUC1* had ever been tested in humans before this trial. We note that neither 5E5 nor antibodies that bind to a MUC1 “heterodimer” recognize MUC1*. Eight patients have already been treated with huMNC2-CAR44. The next 8 patients will be treated with huMNC2-CAR22 to enable comparison and inform decision as to which CAR to bring forward for completion of Phase 1 and entry into Phase 2. huMNC2-CAR22 differs from huMNC2-CAR44 in that it is resistant to exhaustion. CAR22 achieves greater in vivo persistence due to Sadelain’s “1XX” mutations of Tyr to Phe in 2 of the 3 ITAMs, which prevent Tyr phosphorylation and signaling, leaving signaling through ITAM 1 alone. Trial Design: Dose escalation or de-escalation is tested in cohorts of 3 patients each using standard “3+3” dose-finding, with the starting dose of 3.3x105 CAR+ T cells/kg up to a maximum of 1.0x107 CAR+ T cells/kg. Patients receive cyclophosphamide (300 mg/m2/day) and fludarabine (30 mg/m2/day) for 3 days prior to CAR T cell infusion. Safety will be evaluated by CTCAE version 5.0 and Lee criteria. Anti-tumor activity will be assessed by imaging studies completed between 1 and 3 months after huMNC2-CAR T cell infusion for determination of response by RECIST 1.1 or by FDG PET modified PERCIST for patients with predominant bone disease. Inclusion Criteria: Patients with confirmed diagnosis of breast cancer, with documented ER, PR, and HER2 status per ASCO/CAP guidelines. Patients with MUC1* expression of at least 30% by IHC. Patients must have received standard metastatic systemic therapy per NCCN guidelines which are known to confer benefit. No maximum on number of prior treatments. Patients must have received at least 2 or 3 prior lines of chemotherapy in the metastatic setting. Exclusion Criteria: Patients requiring >15 mg of prednisone per day or immunosuppressives; patients with major organ dysfunction; Serum creatinine > 2 mg/dL; Bilirubin ≥ 1.5 mg/dL; AST/ALT ≥ 2.5 x upper limit normal; 3x upper limit for patients with known liver metastasis; significant pulmonary dysfunction; significant cardiovascular abnormalities; ANC < 1000/mm3. Primary Objectives: To determine the safety and maximally tolerated cell dose (MTD) and recommended phase 2 cell dose (RP2D) of ex vivo expanded autologous huMNC2-CAR T cells for patients with advanced MUC1* positive breast cancer using CTCAE version 5.0 and Lee criteria. Secondary: Determine duration of in vivo persistence and phenotype of adoptively transferred huMNC2-CAR T cells. Determine antitumor activity by RECIST 1.1. Determine MTD/RP2D. Contact: City of Hope Comprehensive Cancer Center Joanne Mortimer, MD 1-800-826-4673 Minerva18625@coh.org Citation Format: Cynthia Bamdad, Joanne Mortimer, Yuan Yuan, Jennifer M. Specht, Benoit Smagghe, Stephen Chi-Min Lin, Andrew Stewart, Danica Walkley, Mark Carter, Timothy Synold, Vishwas Parekh, Kevin Yi, Jac-Leen Nash, Michael Nash, Qing Liu-Michael, Stanley Hamilton, Stephen Forman. 1st-in-human CAR T targets MUC1 transmembrane cleavage product [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-19-03.

Generation of iPSC derived CD19 CAR iNK cells for treatment of autoimmune disorders

Abstract Treatment of autoimmune diseases (ADs) relies on broad immunosuppressive agents that are often not curative. Autologous CAR T cell approaches demonstrated disease remission in patients with Systemic lupus erythematosus (SLE). Among cellular abnormalities typical for ADs, NK cells dysfunction was reported. We believe that using iPSC derived CD19 CAR NK cells (iNK cells) to eliminate disease-causing circulating plasma cells could be a novel therapeutic approach for ADs mediated by B cells. Evotec’s validated GMP iPSC line was genetically modified by a knock-in of a CD19-CAR and differentiated into iNK cells using a feeder-free 3D differentiation process. Successful knock-in was confirmed by flow cytometry. Expression of the CAR did not negatively impact the differentiation of the iNK cells. The CD19 CAR iNK cell phenotype and scRNA sequencing profiles are comparable to blood-derived NK cells. To evaluate the ability of CD19 CAR iNK cells to selectively eliminate primary B cells, patient-derived B cell chronic lymphatic leukemia (CLL) cells and primary B cells from healthy donors were co-cultured with CAR iNK cells. Compared to wildtype (WT) iNK cells, CD19 CAR iNK showed specific killing of CD19-positive CLL cells and primary B cells. iPSC-derived CD19-CAR NK cells show increased cytotoxicity and specific targeting of CD19 positive primary patient and healthy subject derived B cells, demonstrating their potential suitability for the treatment of ADs such as SLE.

Treatment of concomitant myasthenia gravis and Lambert-Eaton myasthenic syndrome with autologous CD19-targeted CAR T cells

Myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS) are autoimmune disorders affecting neuromuscular transmission. Their combined occurrence is rare, and treatment remains challenging. Two women diagnosed with concomitant MG/LEMS experienced severe, increasing disease activity despite multiple immunotherapies. Anti-CD19 chimeric antigen receptor (CAR) Tcells have shown promise for treating autoimmune diseases. This report details the safe application of anti-CD19 CAR Tcells for treating concomitant MG/LEMS. After CAR Tcell therapy, both patients experienced rapid clinical recovery and regained full mobility. Deep B cell depletion and normalization of acetylcholine receptor and voltage-gated calcium channel N-type autoantibody levels paralleled major neurological responses. Within 2months, both patients returned to everyday life, from wheelchair dependency to bicycling and mountain hiking, and remain stable at 6 and 4months post-CAR Tcell infusion, respectively. This report highlights the potential for anti-CD19 CAR Tcells to achieve profound clinical effects in the treatment of neuroimmunological diseases.

CD8 T cells with an exhaustion-like phenotype remain highly functional in hematologic tumors

Abstract Loss of immunosurveillance in solid tumors is associated with CD8 T cell dysfunction/exhaustion (TEX). Immunotherapies target TEX differentiation, which may be modified by differences in microenvironments across cancer types and tissue sites. We characterized TEX differentiation in bone marrow (BM), where liquid tumors reside, using mouse models of myeloma and B cell leukemia progressing after autologous stem cell transplantation and CD19-directed CAR T cells respectively. We used flow cytometry and concurrent analysis of RNA expression and DNA accessibility in single cells. We identified a novel CD8 T cell subset with a terminally exhausted phenotype that retained functional capacity, including secretion of cytotoxic molecules and IFNγ. These cells are referred to as interferon-Gamma-secreting, Phenotypically Exhausted (TG-PhEX). Expression of functional genes in TG-PhEX correlated with Batf expression and accessibility within the BATF motif. Chromatin remodeling in stemness associated genes indicated a loss of self-renewal capacity. Indeed, disease progression was associated with a lack of TG-PhEX expansion and not dysfunction as TG-PhEX effectively killed myeloma with comparable activity to CX3CR1+ TEX. Importantly, we observed analogous cells in myeloma and lymphoma patients. TG-PhEX are a clinically relevant target for immunotherapy of hematologic cancers and demonstrate differences in TEX differentiation across tumor sites and cancer subtypes.

Autologous HER2-specific CAR T cells after lymphodepletion for advanced sarcoma: a phase 1 trial.

In this prospective, interventional phase 1 study for individuals with advanced sarcoma, we infused autologous HER2-specific chimeric antigen receptor T cells (HER2 CAR T cells) after lymphodepletion with fludarabine (Flu) ± cyclophosphamide (Cy): 1 × 108 T cells per m2 after Flu (cohort A) or Flu/Cy (cohort B) and 1 × 108 CAR+ T cells per m2 after Flu/Cy (cohort C). The primary outcome was assessment of safety of one dose of HER2 CAR T cells after lymphodepletion. Determination of antitumor responses was the secondary outcome. Thirteen individuals were treated in 14 enrollments, and seven received multiple infusions. HER2 CAR T cells expanded after 19 of 21 infusions. Nine of 12 individuals in cohorts A and B developed grade 1-2 cytokine release syndrome. Two individuals in cohort C experienced dose-limiting toxicity with grade 3-4 cytokine release syndrome. Antitumor activity was observed with clinical benefit in 50% of individuals treated. The tumor samples analyzed showed spatial heterogeneity of immune cells and clustering by sarcoma type and by treatment response. Our results affirm HER2 as a CAR T cell target and demonstrate the safety of this therapeutic approach in sarcoma. ClinicalTrials.gov registration: NCT00902044 .

Abstract CT096: Phase I first-in-human MUC1* targeted autologous CAR T cells for the treatment of metastatic breast cancers

Abstract Purpose: First-in-human Phase I study for advanced MUC1* positive breast cancer with autologous T cells engineered to express either a chimeric antigen receptor, huMNC2-CAR44 or huMNC2-CAR22, which specifically bind to a cleaved form of MUC1 (MUC1*); evaluate the safety and preliminary anti-tumor activity. Methods: MUC1* (muk 1 star) is the growth factor receptor form of MUC1, created by cleavage and release of the N-terminal portion of MUC1. The targeting antibody, huMNC2, only recognizes the conformational epitope created when MUC1 is cleaved by specific tumor-associated enzymes that are correlated with poor prognosis. huMNC2 does not bind to full-length MUC1, which is expressed on all normal epithelial cells. huMNC2-scFv was incorporated into huMNC2-CAR44, comprising a CD8 hinge and transmembrane region, 4-1BB costimulatory domain and wild-type CD3z. huMNC2-scFv was also incorporated into huMNC2-CAR22 wherein the hinge, transmembrane and co-stimulatory portions were derived from CD28 and CD3z bears the 1XX mutations to increase in vivo persistence. Inclusion criteria require that the patient’s tumor is at least 30% MUC1* positive and that patient has progressed through 2 or 3 prior therapies, while in the metastatic setting. Patients receive standard Cy/Flu lymphodepletion approximately 3-days before CAR T treatment, administered at 1 of 4 dose levels ranging from 3.3X10^5 up to 1.0X10^7 CAR+ T cells. Results: To date, 8 patients have been treated with huMNC2-CAR44. No patients experienced neuro toxicities. No off-target toxicities were observed. 3 patients experienced CRS Grade 1-3. In 6 of the 8 patients, side effects were non-existent or minimal. However, one patient experienced a Grade 5 SAE that was deemed to be possibly related to the treatment. Best responses include Partial Responses and Stable Disease at a low CAR-T dose. Greatest efficacy was observed for patients whose biopsy showed H Scores >120. Patients are currently being enrolled for treatment with huMNC2-CAR22, where the 1XX mutations are expected to increase in vivo persistence, durability of response and reduced incidence of CRS. Conclusions: These data support a conclusion that the MUC1* antibody, huMNC2, is safe and could have high therapeutic value as a CAR T treatment for solid tumors with moderate to high antigen density. As the huMNC2-CAR22 (1XX) trial proceeds, we will assess if patient responses mirror our animal results that show that the 1XX mutations confer increased persistence, reduced exhaustion and the ability to kill tumors with low antigen density. Citation Format: Cynthia Carol Bamdad, Joanne E. Mortimer, Yuan Yuan, Jennifer M. Specht, Andrew K. Stewart, Benoit J. Smagghe, Stephen C. Lin, Mark G. Carter, Tim W. Synold, Mark D. Fleming, Stanley R. Hamilton, Vishwas Parekh, Danica M. Walkley, Qing Liu-Michael, Kevin R. Yi, Jac-Leen S. Nash, Michael J. Nash, Stephen J. Forman. Phase I first-in-human MUC1* targeted autologous CAR T cells for the treatment of metastatic breast cancers [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 CT096.

Abstract 6322: CCTx-001 CAR T-cells targeting the AML specific antigen IL-1RAP show robust pre-clinical anti-tumor efficacy

Abstract Despite significant advancements in acute myeloid leukemia (AML) treatment, patients with relapsed/refractory (r/r) AML have limited therapeutic options. Novel approaches are urgently needed. CAR T-cell therapy has shown remarkable success in hematological malignancies. However, its application in AML has been hampered by the absence of highly AML-specific antigens, making current CAR T-cell AML therapies under development poorly tolerated and effective. This pre-clinical study introduces a novel CAR T-cell therapy, CCTx-001, specifically designed to target IL-1RAP, a 78-kDa transmembrane glycoprotein. IL-1RAP, is highly expressed on AML cells but not on healthy hematopoietic stem and progenitor cells (CD34+ HSPC). Additionally, transcriptomic analyses reveal a correlation between high IL-1RAP expression and poor prognosis in AML patients. IL-1RAP's predominant presence on myeloid leukemia cells, coupled with their dependence to IL-1RAP-related pathways for their survival, presents a promising avenue for CAR T-cell therapy without the risk of treatment-induced antigen loss. CCTx-001, an autologous CAR T-cell therapy, was developed to target IL-1RAP on AML cells. It comprises CD8+ and CD4+ T-cells transduced with a highly specific anti-IL-1RAP Single-Chain Variable Fragment (scFv), an IgG1 hinge region, CD28, 4-1BB co-stimulatory domains, and a CD3ζ activation domain. In vitro experiments confirmed CCTx-001's efficacy in killing AML cell lines and primary AML cells of varying IL-1RAP expression levels, also demonstrating cytotoxicity and cytokine release that was dependent on the (E:T) ratio and target expression. Furthermore, in vivo studies using immunocompromised NCG mice confirmed CCTx-001's ability to target IL-1RAP and inhibit the growth of IL-1RAP-positive human AML tumor xenografts, leading to increased survival time. Biodistribution analyses confirmed the successful adoptive transfer, expansion and persistence of CCTx-001 CAR T-cells in vivo, only when injected into IL-1RAP-expressing tumor-bearing mice, which correlated with reduced levels of circulating AML cells. The promising preclinical data presented herein warrant the evaluation of CCTx-001 CAR T-cell therapy in clinical trials for r/r AML patients. CCTx-001 CAR T-cell therapy offers a potential breakthrough in addressing the unmet medical needs of AML patients with resistant or refractory disease. Citation Format: Edouard De Dreuzy, Soha Reda El Sayed, Delphine Genin, Clementine Primus, Lucie Bouquet, Alexis Collette, Olivier Favre-Bulle, Erik Rutjens, Jens Hasskarl, Ksenija Pavletic, Marina Deschamps, Christophe Ferrand, Richard C. A. Sainson. CCTx-001 CAR T-cells targeting the AML specific antigen IL-1RAP show robust pre-clinical anti-tumor efficacy [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 6322.

CAR T-cells for T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) has a dismal prognosis in case of relapsed or refractory disease. Contrary to B-ALL, few immunotherapies are available for T-ALL. Use of autologous CAR T-cells is challenging due to shared antigen between leukemic and normal T-cells responsible for fratricide and T-cell aplasia in case of persistence of CAR T-cells. Moreover, risk of contamination of the apheresis product by lymphoblasts remains an issue. To counteract these challenges several methods are used to edit T-cell such as protein expression blocker, CRISPR/Cas9 and base-editing. Other possibility is to use autologous T-cells naturally selected in vitro or donor-derived T-cells allowing gene edition and reduction of the risk of graft vs host disease. Encouraging results are obtained in preclinical and clinical studies for early response rate but several questions remain. Is the persistence of these cells requiring for maintaining the remission? Is it feasible to recover a target-negative T-cell population without risk of profound immunosuppression? Has an allogeneic stem cell transplantation to be planned for patients after CAR T-cells infusion? What about the risk of engineered T-cells in the long term?

Autologous anti-GD2 CAR T cells efficiently target primary human glioblastoma

Glioblastoma (GBM) remains a deadly tumor. Treatment with chemo-radiotherapy and corticosteroids is known to impair the functionality of lymphocytes, potentially compromising the development of autologous CAR T cell therapies. We here generated pre-clinical investigations of autologous anti-GD2 CAR T cells tested against 2D and 3D models of GBM primary cells. We detected a robust antitumor effect, highlighting the feasibility of developing an autologous anti-GD2 CAR T cell-based therapy for GBM patients.

Miniaturized CAR knocked onto CD3ε extends TCR function with CAR specificity under control of endogenous TCR signaling cascade

Immunotherapy using TCR and especially CAR transgenic T cells is a rapidly advancing field with the potential to become standard of care for the treatment of multiple diseases. While all current FDA approved CAR T cell products are generated using lentiviral gene transfer, extensive work is put into CRISPR/Cas mediated gene delivery to develop the next generation of safer and more potent cell products. One limitation of all editing systems is the size restriction of the knock-in cargo. Targeted integration under control of an endogenous promotor and/or signaling cascades opens the possibility to reduce CAR gene size to absolute minimum. Here we demonstrate that a first-generation CAR payload can be reduced to its minimum component - the antigen-binding domain - by targeted integration under control of the CD3ε promoter generating a CAR-CD3ε fusion protein that exploits the endogenous TCR signaling cascade. Miniaturizing CAR payload in this way results in potent CAR activity while simultaneously retaining the primary antigen recognition function of the TCR. Introducing CAR-specificity using a CAR binder only while maintaining endogenous TCR function may be an appealing design for future autologous CAR T cell therapies.

Abstract C117: Preclinical characterization of allogeneic CAR γδ T Cell therapy for prostate cancer targeting a novel dimeric epitope on PSMA

Abstract Introduction: PSMA is a transmembrane glycosylated homodimer overexpressed in >80% of prostate cancers, with increased expression in advanced stages of the disease. Formation of homodimeric PSMA is necessary for enzymatic function and displays epitopes that are potentially more distinct from alternative PSMA-like proteins. Clinically, autologous anti-PSMA αβ CAR T cells have shown initial efficacy with limited therapeutic index. Compared to αβ T cells and other innate cells, γδ T cells are capable of multifunctional innate and adaptive targeting and infiltrate into tumor-associated tissues, including associated tropism for prostate tumor tissues. Additionally, γδ CAR T cells have demonstrated enhanced tumoricidal activity and activation-induced cytokine profiles that may decrease CRS-associated toxicities. We characterized γδ T cells modified from a set of novel scFv-based CARs targeting PSMA for prostate cancer and mapped unique epitopes for binders associated with the most potent CARs. Methods: Phage panning was used to identify anti-PSMA scFv sequences, which were reformatted into IgGs and characterized for binding to both cells expressing endogenous PSMA and recombinant PSMA. Binders with favorable profiles were reformatted into CARs in VH-VL and VL-VH orientations and transduced into Vδ1 T cells, a primarily tissue-resident subset, activated from healthy donor PBMCs. We identified lead CARs based on anti-tumor efficacy both in vitro in coculture assays and in vivo in tumor xenograft models and compared their activity to Vδ1 CAR T cells transduced with a clinically validated benchmark, J591. Epitope mapping of binders in the lead CARs was performed using a funnel of molecular assays including dot blots, competition assays, ELISAs on recombinant PSMA from different species and cross-linking mass spectrometry (XL-MS). Results: High-affinity PSMA binders yielded potent CARs. Lead PSMA CARs demonstrated robust in vitro cytotoxicity and antigen-specific binding to PSMA-expressing cell lines in a manner comparable to, or greater than the J591-based CAR T cells. Additionally, lead PSMA CARs showed anti-tumor control in 22Rv1 human prostate cancer xenografts, a highly resistant model with heterogenous PSMA expression. Epitope mapping studies on binders in lead PSMA CARs identified conformational, membrane-distal epitopes that are distinct from the predicted linear epitope of J591 and relevant comparators. Conclusion: The epitope for a lead PSMA antibody includes residues in a helix involved in PSMA dimer formation. The γδ CAR T construct derived from this binder demonstrates enhanced preclinical performance when compared to the J591 reference CAR T. Combining the features of this novel target and the potential of the γδ-based CAR T approach, the lead PSMA γδ CAR T cells described here are candidates for further clinical development in the context of additional armoring technologies and CAR architecture modifications designed to complement therapeutic potential. Citation Format: Nitya S. Ramadoss, Elizabeth Speltz, Tonya Capillo, Erika Meaddough, Katherine Wang, Natalia Friedland, Jonathan Wong, Alexander G Teague, Aruna Azameera, Smitha Rao Yelaguli Gundurao, Ramandeep Kaur, Morgan Smith-Boeck, Michael Salum, Yvan Chanthery, Shon Green, Marissa Herrman, Kevin P Nishimoto, Blake T Aftab, Arun Bhat. Preclinical characterization of allogeneic CAR γδ T Cell therapy for prostate cancer targeting a novel dimeric epitope on PSMA [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C117.

CAR T-Cell Therapy in Relapsed or Refractory T-Cell Acute Lymphoblastic Leukemia/Lymphoma: A Retrospective Study

Background Patients with relapsed or refractory T cell acute lymphoblastic leukemia/lymphoma (r/r T-ALL/LBL) often have limited treatment options available and poor prognoses. Clinical trials of autologous CD7, donor-derived CD7 and donor-derived CD5 CAR T-cell therapy in r/r T-ALL/LBL conducted in our center have showed encouraging efficacy and a shaky safety. To evaluate the safety and efficacy of the three therapies, we conducted a retrospective study and analyzed the results of the clinical trials across three different CAR T-cell therapies. Methods This is a retrospective comparative analysis of CAR T-cell therapies with different targets and sources in r/r T-ALL/LBL, including a phase Ⅰ trial of autologous CD7 CAR T-cell therapy (NCT04840875), a phase Ⅰ trial (ChiCTR2000034762) and a phase Ⅱ trial (NCT04689659) of donor-derived CD7 CAR T-cell therapy, and a phase Ⅰ trial of donor-derived CD5 CAR T-cell therapy (NCT05032599). Adverse events and pharmacokinetics were not collected after patients received stem-cell transplantation. In univariate analysis, Chi-square test and Fisher's exact test were used to compare categorical outcome; in multivariate analysis, linear regression was used for the continuous outcome and Logistic regression was used for the categorical outcome. Results A total of 102 patients were included in this analysis, consisting three cohorts: 20 patients receiving autologous CD7 CAR T cells, 66 with donor-derived CD7 CAR T-cell therapy, and 16 receiving donor-derived CD5 CAR T cells. Although with comparable complete remission rates, patients in the three cohorts had different adverse events. Especially, patients who received autologous CD7 CAR T-cell therapy had a significant lower severe infection rate than those with donor-derived CD7 CAR T cells (odds ratio [OR], 0.06; 95% confidence interval [95%CI], 0.01 to 1.03; P=0.019 by exact method) and donor-derived CD5 CAR T cells (OR, 0.03; 95%CI, 0.01 to 0.60; P=0.006) (Table 1). Despite that all patients developed grade 3-4 cytopenias, more patients who received autologous CD7 CAR T-cell therapy reverted grade 3-4 cytopenias to grade 2 or lower within one month compared with donor-derived CD7 CAR T cells (OR, 13.00; 95%CI, 3.99 to 42.32; P<0.001) and donor-derived CD5 CAR T cells (OR, 27.86; 95%CI, 3.02 to 257.28; P<0.001). Based on the multivariate analyses, CD7 CAR T-cell therapy led to lower severe infection rate compared with CD5 CAR T-cell therapy (OR, 0.08; 95%CI, 0 to 0.56; P=0.015) (Table 2), and it should be noted that in this study, the vector uesd in autologous and donor-derived CD7 CAR T-cell therapy was different from that in CD5 CAR T-cell therapy; larger proportion of patients treated with CAR T cells manufactured from their own T cells retured all grade 3-4 cytopenias to grade 0-2 within one month (OR, 68.08; 95%CI, 3.21 to 1446.20; P=0.005), versus patients receiving donor-derived therapy. No factors were identified as independently influencing CRS, ICANS and CR/CRi rate at one month, including central nervous system leukemia not associated with ICANS. Although the source of CAR T cells has not been shown to be a factor in CRS and ICANS, patients with autologous CAR T-cell therapy had lower peak levels of cytokines than donor-derived, including IL-6, sCD25 and TNF-α with the maximal P value of 0.02 in multivariate analysis. Conclusion Despite the risk of tumor contamination and CAR T-cell manufacture failure in autologous CD7 CAR T-cell therapy, some clinical experience have emerged against for them recently. In addition to the fact that autologous therapy cause no GVHD and the faster recovery from hematologic toxicity, being beneficial for long-term defense against infection, it produces lower levels of several cytokines in vivo compared to donor-derived therapy, providing a guarantee for lower incidence of CRS and ICANS. Hence, given the comparable remission rate and remarkable safety, autologous CD7 CAR T-cell therapy would be prioritized for recommendation for r/r T-ALL/LBL patients with low tumor load and access to collect enough normal T cells from their own body for CAR T-cell manufacture. CD5 CAR T-cell therapy is regarded as an option for patients with CD5 positive encountering treatment failure or relapse after CD7 CAR T-cell therapy.