CARS1 and plasma cell myeloma: To address the issue of relapse or refractory in multiple myeloma caused by clonal heterogeneity of MM cells, Zah E et al. developed a bispecific CAR-T cells targeting BCMA and CS1, the optimized CAR-T cells exhibited robust activity against heterogeneous MM cells, outperforming T cells expressing individual BCMA or CS1-CARs [84].