Engineering BCMA CAR T cells for myeloma-targeted cargo delivery

Clinical responses with chimeric antigen receptor (CAR) T cells are encouraging, however, primary resistance and relapse after therapy prevent durable remission in a large fraction of cancer patients. One of the underlying causes comprises apoptosis resistance mechanisms in cancer cells that limit killing by CAR T cells. Therefore, we developed a technology that boosts tumor cell apoptosis induced by CAR T cells. We reveal that B cell maturation antigen (BCMA) CAR T cells equipped with a granzyme B-NOXA fusion construct improves killing of multiple myeloma (MM) cells, both in vitro and in a xenograft mouse model, by localizing NOXA to cytotoxic granules that are released into cancer cells upon contact. Since MM cells critically depend on MCL-1 expression, inhibition by its natural ligand NOXA effectively induces apoptosis. Overall, this strategy allows specific delivery of cargo into cancer cells and improves killing efficacy of CAR T cells in a tailor-made manner. ### Competing Interest Statement Authors Thomas Kimman, Zsolt Sebestyen and Victor Peperzak are inventors on patent WO/2023/031215 that builds on the optimized killing technology for CAR T cells described in this manuscript.