In order to improve efficacy of CAR T-cell therapy in RRMM, different strategies are being investigated including the targeting of other MM antigens such as G-protein-coupled receptor, class C group 5 member D (GPRC5 D) [NCT05016778—POLARIS, NCT05219721, NCT05325801]; signaling lymphocyte activation molecule, family member 7 (SLAMF7) [NCT04499339—CARAMBA-1, NCT03958656] as well as simultaneously targeting two different MM antigens such as CD19 and BCMA (NCT04236011, NCT04182581, ChiCTR-OIC-17011272). This evidence concerns the gene CD19 and Miyoshi myopathy.