A phase I/II trial evaluated the safety and efficacy of bispecific BC19 CAR T cells targeting BCMA and CD19 in patients with relapsed/refractory multiple myeloma (R/R MM). The study enrolled 50 patients, with the primary endpoint being safety. BC19 CAR T cells were well tolerated, with 8% experiencing grade 3 or higher cytokine release syndrome (CRS) and 4% having grade 1 neurotoxic events. Secondary endpoints included an overall response rate (ORR) of 92%, median progression-free survival (PFS) of 19.7 months, median overall survival (OS) of 19.7 months, and median duration of response (DOR) not reached. The study demonstrated that BC19 CAR T cells are feasible, safe, and effective in treating R/R MM. Preclinical results showed that BC19 CAR T cells specifically recognize BCMA and CD19-positive cancer cells and exhibit potent antitumor activity in xenograft models. In vivo studies confirmed the therapeutic ability of BC19 CAR T cells in xenograft models, with significant tumor growth inhibition. The study also showed that BC19 CAR T cells can target both BCMA and CD19, which are expressed on myeloma cells, and that they are effective even in patients with limited prior treatment. The safety profile of BC19 CAR T cells was favorable, with CRS and neurotoxicity being the most common adverse events. The study highlights the potential of bispecific BC19 CAR T cells as a promising treatment for R/R MM.A phase I/II trial evaluated the safety and efficacy of bispecific BC19 CAR T cells targeting BCMA and CD19 in patients with relapsed/refractory multiple myeloma (R/R MM). The study enrolled 50 patients, with the primary endpoint being safety. BC19 CAR T cells were well tolerated, with 8% experiencing grade 3 or higher cytokine release syndrome (CRS) and 4% having grade 1 neurotoxic events. Secondary endpoints included an overall response rate (ORR) of 92%, median progression-free survival (PFS) of 19.7 months, median overall survival (OS) of 19.7 months, and median duration of response (DOR) not reached. The study demonstrated that BC19 CAR T cells are feasible, safe, and effective in treating R/R MM. Preclinical results showed that BC19 CAR T cells specifically recognize BCMA and CD19-positive cancer cells and exhibit potent antitumor activity in xenograft models. In vivo studies confirmed the therapeutic ability of BC19 CAR T cells in xenograft models, with significant tumor growth inhibition. The study also showed that BC19 CAR T cells can target both BCMA and CD19, which are expressed on myeloma cells, and that they are effective even in patients with limited prior treatment. The safety profile of BC19 CAR T cells was favorable, with CRS and neurotoxicity being the most common adverse events. The study highlights the potential of bispecific BC19 CAR T cells as a promising treatment for R/R MM.