Bispecific and split CAR T cells targeting CD13 and TIM3 eradicate acute myeloid leukemia

Abstract Chimeric antigen receptor (CAR) T cells have radically improved the treatment of B cell–derived malignancies by targeting CD19. The success has not yet expanded to treat acute myeloid leukemia (AML). We developed a Sequentially Tumor-Selected Antibody and Antigen Retrieval (STAR) system to rapidly isolate multiple nanobodies (Nbs) that preferentially bind AML cells and empower CAR T cells with anti-AML efficacy. STAR-isolated Nb157 specifically bound CD13, which is highly expressed in AML cells, and CD13 CAR T cells potently eliminated AML in vitro and in vivo. CAR T cells bispecific for CD13 and TIM3, which are upregulated in AML leukemia stem cells, eradicated patient-derived AML, with much reduced toxicity to human bone marrow stem cells and peripheral myeloid cells in mouse models, highlighting a promising approach for developing effective AML CAR T cell therapy.