In vitro function verification of S103 BCMA CAR T cells. (A) Schematic representation of S103 CAR structure. (B) CAR transduction efficiency of S103 CAR T cells. (C) Cell viability of S103 CAR T cells at different culture stages, the x-axis represents the culture days, the red line represents CAR T-cell group, and the blue line represents T-cell group. (D) The cytotoxicity of S103 CAR T cells toward NCI-H929-LUC cancer cells, the x-axis represents the effector-to-target cell ratios, the red line represents CAR T-cell group, and the blue line represents T-cell group. (E) Schematic of animal mode protocol, 6 mice per group, half male and half female, every mouse was injected with 1 × 10⁷ MM.1s-Luc cells. After 8 days, CAR T-cell group was injected with 0.5E7 per mouse CAR⁺ T cells, T-cell group was injected with the same total number of T cells as the CAR T-cell group, and medium control group was injected with cell preservation solution. (F-G) Bioluminescence image analysis. ∗P < .05; ∗∗∗P < .001 (n = 4).