Allo-defensive, multiplex base-edited, anti-CD38 CAR T cells for 'off-the-shelf' immunotherapy

Chimeric antigen receptor (CAR) T-cell therapies are being widely investigated in both autologous and allogeneic settings, with gene editing providing new strategies to address barriers to mismatched cell therapies. Currently 'universal' donor-derived T-cell therapies require intensive lymphodepletion and are still prone to host-mediated rejection. CD38, a transmembrane glycoprotein involved in cell activation and bioenergetics, is a promising immunotherapy target for hematologic malignancies. Disruption of CD38 expression using base editing prevented fratricide between T cells expressing anti-CD38 CAR (CAR38). Additional base editing enabled generation of 'universal' donor CAR38-T cells, devoid of endogenous TCRαβ and human leukocyte antigen (HLA) molecules after disruption of T-Cell Receptor Beta Constant (TRBC), Beta-2 Microglobulin (B2M), and Regulatory Factor X5 (RFX5). Removal of cell surface HLA expression enabled evasion of anti-HLA antibodies in sera from sensitized donors and reduced allo-stimulation in mixed lymphocyte cultures, while TCRαβ disruption prevented allo-reactivity. In mixed lymphocyte cultures, CAR38 expression enabled potent 'allo-defense' activity against CD38+ allo-reactive cells. Multiplex base-edited CAR38-T cells exhibited antigen-specific antileukemic activity against human B, T, and myeloid malignancies and inhibited disease progression in humanized murine xenograft models. CAR38-T cells offer a potent 'off-the-shelf' strategy against CD38+ hematologic malignancies and long-lived plasma cells which can be associated with auto-antibody production.