TriPRIL CARTs specifically eradicate MM cells in vivo. Antitumor efficiency of UTDs and BCMA, APRIL, and TriPRIL CARTs was assessed in a xenograft model of MM. (A) Experimental design: NSG mice were injected with 1 × 10⁶ MM.1S myeloma cells and tumor burden was monitored by BLI over time. After tumor engraftment and randomization, the mice were treated with a single dose of UTDs or BCMA, APRIL, or TriPRIL CARTs from the same donors 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 experimental groups at the indicated time points. (D) Persistence of CARTs (CD3⁺mCherry⁺) measured in the peripheral blood by flow cytometry. Data points indicate the means ± SEM of 2 normal donors with 4 mice per each group. **P < .01 by 2-way ANOVA.