Current Insights into CAR T-Cell-Based Therapies for Myelodysplastic Syndrome.

CD84: A Novel Target for CAR T-Cell Therapy for Acute Myeloid Leukemia

In acute myeloid leukemia (AML), malignant stem cells hijack the normal bone marrow niche where they are largely protected from the current therapeutic approaches. Thus, eradicating these progenitors is the ultimate challenge in the treatment of this disease. Specifically, the development of chimeric antigen receptors (CARs) against distinct mesenchymal stromal cell subpopulations involved in the maintenance of leukemic stem cells within the malignant bone marrow microenvironment could represent a new strategy to improve CAR T-cell therapy efficacy, which is still unsuccessful in AML. As a proof of concept, we generated a novel prototype of Tandem CAR, with one specificity directed against the leukemic cell marker CD33 and the other against the mesenchymal stromal cell marker CD146, demonstrating its capability of simultaneously targeting two different cell types in a 2D co-culture system. Interestingly, we could also observe an in vitro inhibition of CAR T cell functionality mediated by stromal cells, particularly in later effector functions, such as reduction of interferon-gamma and interleukin-2 release and impaired proliferation of the CAR+ effector Cytokine-Induced Killer (CIK) cells. Taken together, these data demonstrate the feasibility of a dual targeting model against two molecules, which are expressed on two different target cells, but also highlight the immunomodulatory effect on CAR CIK cells exerted by stromal cells, confirming that the niche could be an obstacle to the efficacy of CAR T cells. This aspect should be considered in the development of novel CAR T cell approaches directed against the AML bone marrow niche.

Harnessing the CD2 axis to broaden and enhance the efficacy of CAR T-cell therapies.

Anti-CD19 CAR T Therapy Following Autologous HSCT May be Safe and Effective in Patients with Refractory Large B-Cell Lymphoma

B-cell maturation antigen chimeric antigen receptor T-cell re-expansion in a patient with myeloma following salvage programmed cell death protein 1 inhibitor-based combination therapy.

Peripheral Blood Stem Cells Vs Bone Marrow: Stem Cell Source Comparison for Patients Acute Myeloid Leukemia and Myelodysplastic Syndrome Receiving an Allogeneic Stem Cell Transplantation from a 10/10 Matched Donor. Study from the French Society of Bone Marrow Transplantation and Cell Therapies (SFGM-TC)

Identification of Two CAR T-Cell Populations Associated with Complete Response or Progressive Disease in Adult Lymphoma Patients Treated with Axi-Cel

Immune response to three doses of mRNA SARS-CoV-2 vaccines in CD19-targeted chimeric antigen receptor Tcell immunotherapy recipients.

Chimeric antigen receptor (CAR) T-cell therapy is a new and effective treatment for patients with hematologic malignancies. Clinical responses to CAR T cells in leukemia, lymphoma, and multiple myeloma have provided strong evidence of the antitumor activity of these cells. In patients with refractory or relapsed B-cell acute lymphoblastic leukemia (ALL), the infusion of autologous anti-CD19 CAR T cells is rapidly gaining standard-of-care status and might eventually be incorporated into frontline treatment. In T-ALL, however, leukemic cells generally lack surface molecules recognized by established CAR, such as CD19 and CD22. Such deficiency is particularly important, as outcome is dismal for patients with T-ALL that is refractory to standard chemotherapy and/or hematopoietic stem cell transplant. Recently, CAR T-cell technologies directed against T-cell malignancies have been developed and are beginning to be tested clinically. The main technical obstacles stem from the fact that malignant and normal T cells share most surface antigens. Therefore, CAR T cells directed against T-ALL targets might be susceptible to self-elimination during manufacturing and/or have suboptimal activity after infusion. Moreover, removing leukemic cells that might be present in the cell source used for CAR T-cell manufacturing might be problematic. Finally, reconstitution of T cells and natural killer cells after CAR T-cell infusion might be impaired. In this article, we discuss potential targets for CAR T-cell therapy of T-ALL with an emphasis on CD7, and review CAR configurations as well as early clinical results.

Chimeric antigen receptor (CAR) T-cell therapy has been shown to produce profound results in the treatment of certain hematologic malignancies, however treatment of solid tumors with CAR T cells has not been as successful. Studies have suggested that T-cell exhaustion plays a role in limiting the ability of CAR T cells to eradicate solid tumors. Additionally, stem-like qualities of T cells have been associated with better outcomes in patients treated with cellular therapies, including CAR T cells. Therefore, maintaining stem-like qualities and overcoming T-cell exhaustion may be key to improving clinical efficacy of CAR T cells in patients with solid tumors. ROR1 is a cell surface antigen expressed in several solid tumor types and chronic lymphocytic leukemia (CLL). ROR1 expression has been reported in 57% of triple-negative breast cancer (TNBC), as well as 42% of adenocarcinoma and 12% of squamous cell carcinoma subtypes of non-small cell lung cancer (NSCLC). These expression data of ROR1 in TNBC and NSCLC provide support for anti-ROR1 agents as a therapeutic strategy for these cancers. LYL797 is a novel, ROR1-targeted chimeric antigen receptor (CAR) T-cell product that incorporates genetic and epigenetic reprogramming technologies, Gen-R and Epi-R, to overcome barriers of CAR T-cell therapies in solid tumors. The ROR1-specific CAR contains a single-chain variable fragment (scFv) derived from an R12 rabbit monoclonal antibody that recognizes and binds with high specificity to human ROR1. Gen-R is ex vivo genetic reprogramming technology that engineers CAR T cells to overexpress c-Jun. Dysregulation of activator protein 1 (AP-1) has been implicated in CAR T-cell exhaustion, and studies have demonstrated that overexpression of c-Jun renders CAR T cells less susceptible to exhaustion, enhancing both anti-tumor efficacy and persistence in preclinical models of hematologic and solid tumors. Epi-R is a proprietary optimized manufacturing process that results in maintenance of stem-like phenotype and function of T-cell products. In preclinical studies LYL797 cells reprogrammed with Gen-R and Epi-R led to improved functional activity in the presence of ROR1+ tumor cells compared to conventional ROR1 CAR T cells. Additional studies are underway to determine the mechanisms by which antitumor activity of LYL797 in ROR1-positive solid tumor xenograft models is enhanced. LYL797 is anticipated to enter into Phase 1 clinical trials for TNBC and NSCLC in 2022. Citation Format: Spencer Park, Courtney Simianer, Sydney Spadinger, Xiao Wang, Purnima Sundar, Shobha Potluri, Rachel Lynn, Bijan Boldajipour, Grace Wang, Neeraj Sharma, Hajime Hiraragi, Veena Krishnamoorthy, Suman Kumar Vodnala, E-Ching Ong, Chang-Chih Wu, Martin Wohlfahrt, Byoung Ryu, Lisa Song, Brian D. Weitzner, Howell Moffett, Marc Lajoie, Scott Boyken, Tamer Shabaneh, Shivani Srivastava, Tina Albertson, Blythe Sather. LYL797, a ROR1 CAR T-cell therapy with genetic and epigenetic reprogramming for solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2754.

The development of chimeric antigen receptor (CAR) T-cell therapy has led to a paradigm shift in cancer treatment. However, patients often do not benefit from CAR T-cell therapy due to poor persistence of the adoptively transferred cells. Development of strategies based on the generation and maintenance of long-lasting memory T cells may expand the therapeutic effects of CAR T cells. Mitochondrial metabolic pathways play crucial roles in regulating the fate, function, and longevity of T cells. Here, we discuss how reprogramming of mitochondrial metabolic pathways influences function, persistence, and determination of CAR T-cell fate toward a memory phenotype. Moreover, we explore how mitochondrial activity determines persistence and the clinical outcome of CAR T-cell therapy. In addition, we review some strategies for manipulating CAR T-cell mitochondria to improve the survival of CAR T cells.

Immunomodulation with Azacytidine and Donor Lymphocyte Infusion Following Sequential Conditioning Allogenic Stem Cell Transplantation Improves Outcome of Unfavorable AML

Chimeric antigen receptor (CAR) T-cell therapy has shown remarkable efficacy in cancer treatment. Nevertheless, most patients receiving CAR T cells relapse within 5 years of treatment. CAR-mediated trogocytosis (CMT) is a potential tumor escape mechanism in which cell surface proteins transfer from tumor cells to CAR T cells. CMT results in the emergence of antigen-negative tumor cells, which can evade future CAR detection, and antigen-positive CAR T cells, which have been suggested to cause CAR T-cell fratricide and exhaustion. Whether CMT indeed causes CAR T-cell dysfunction and the molecular mechanisms conferring CMT remain unknown. Using a selective degrader of trogocytosed antigen in CAR T cells, we show that the presence of trogocytosed antigen on the CAR T-cell surface directly causes CAR T-cell fratricide and exhaustion. By performing small molecule screening using a custom high-throughput CMT screening assay, we found that the cysteine protease cathepsin B is essential for CMT and that inhibition of cathepsin B is sufficient to prevent CAR T-cell fratricide and exhaustion, leading to improved long-term in vitro and in vivo CAR T-cell persistence and in vitro antitumor activity. Our data demonstrate that it is feasible to separate CMT from cytotoxic activity, that CAR T-cell persistence, a key factor associated with clinical CAR T-cell efficacy, is directly linked to cathepsin B activity in CAR T cells, and that it is possible to improve CAR T-cell function through selective inhibition of CMT.

Outcomes of Patients with Large B-Cell Lymphomas and Progressive Disease Following CD19-Specific CAR T-Cell Therapy

CRG-023 Is a Novel Tri-Specific CAR T Product Candidate Engineered to Prevent Antigen Escape and Sustain Durable Anti-Tumor Functionality Against B-Cell Malignancies