TriPRIL CARTs specifically eradicate BCMA⁻MM cells in vivo. Antitumor activity of UTD, BCMA, and TriPRIL CARTs in a xenograft model of BCMA⁻ MM. (A) Experimental design indicating tumor cells, timeline, doses, and imaging time points. Mice were randomized after tumor engraftment and before injection with a single dose of T cells from the same donors that had been normalized to the same number of total T cells. (B) Representative BLI of myeloma xenografts over time. (C) Quantification of flux (photons per second) in the 4 groups at the indicated time points. *P < .05 by 2-way ANOVA at day 14, before the onset of allogeneic responses. Data points show means ± SEM of 2 normal donors with 5 mice per each group. (D) In vivo comparison of tumor growth kinetics of parental MM.1S and MM.1S BCMA KO cells. NSG mice were injected with 1 × 10⁶ tumor cells, and tumor burden was monitored by weekly bioluminescence imaging. Data points indicate means ± SEM of flux fold change compared with baseline (day 7); n = 5 mice per group.