Dual-targeting allogeneic CAR T-cells for universal therapy of T-cell malignancies

Abstract Relapsed and refractory T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoma (TCL) are aggressive hematologic malignancies with limited therapeutic options and 3-year survival rates below 20 percent. While the development of chimeric antigen receptor (CAR)-T cell therapies have shown promise in B-cell cancers, targeting

T-cell malignancies has been hindered by the shared antigen space between healthy and malignant cells leading to CAR T cell self-targeting and a heightened risk of T- cell aplasia. CD5 and CD7 are key surface markers for T-ALL/TCL, with about 90% of T-cell malignancies expressing one or both markers. The autologous CD5.CAR-T and CD7.CAR-T cell therapies developed at Baylor College of

Medicine and licensed to March Biosciences show safety, feasibility, and signs of durable efficacy in Phase 1 clinical trials for T-cell malignancies. However, these trials have faced manufacturing challenges in many patients and benefits to others have been abrogated by antigenically heterogenous tumors. To overcome these limitations

and enhance anti-tumor activity against T-cell cancers, March Biosciences proposes to develop partially- matched donor-derived, dual-specific CAR-T cells (CD5/CD7.CAR-T cells). These CD5/CD7.CAR-T cells are uniquely engineered for fratricide resistance and are produced from haploidentical, CD45RA-depleted donor T-

cells (RAD-T) to minimize the risk of graft versus host disease using a rapid current good manufacturing practice (cGMP) compliant process. Safety and controllability will be further augmented by integrating a drug-inducible caspase 9 (iC9) system allowing precise in vivo control of CAR-T cells post-infusion. This project aims to develop

CD5/CD7.CAR.RAD-T cells for highest activity against malignant T-cells with varying antigen expression in both in vitro and in vivo models, and to demonstrate controlled CAR-T cell elimination by activating the caspase 9- induced apoptosis. To streamline CAR-T cell production and reduce costs for optimal scalability, March

Biosciences is optimizing cGMP process to accelerate the manufacturing of CD5/CD7.CAR.RAD-T cells. By transitioning to a rapid, closed-circuit system, March Biosciences seeks to consolidate T-cell stimulation, transduction, and expansion into a single vessel over 4 days. The target total production timeline is 9 days

inclusive of final release testing thus ensuring a potent and rapidly available product for patients with aggressive disease. Upon completion of this project, March Biosciences will have selected a lead candidate and finalized a cGMP-ready process for manufacturing dual-targeting CAR-Ts enabling subsequent clinical testing in Phase 1/2

trials in patients with refractory and relapsed T-cell malignancies.