Figure 3.

BCMA(171)-Targeted CAR T Cells Provide Long-Term Immunity against Re-challenge with a Human MM Cell Line Irrespective of CAR Co-stimulatory Domain

OPM2-ffLuc cells (1 × 10⁶) were injected via tail vein into NSG mice. On day 4, mice were treated with a single injection of either control CD19(SJ25C1)- or BCMA(171)-targeted CAR T cells containing a CD28 or a 4-1BB co-stimulatory domain (1 × 10⁶ CAR⁺). (A) Treatment with BCMA(171) CAR T cells provide significantly prolonged survival compared to treatment with CD19(SJ25C1) CAR T cells. Survival between mice treated with BCMA(171) CAR T cells differing by co-stimulatory domain were not significant. (B) Representative ventral and dorsal BLI at day 21 shows elimination of OPM2 MM cells by both groups of BCMA(171) CAR T cells. (C) Long-term surviving mice from 4a were re-challenged with OMP2 cells 98 days after their initial OPM2 injection (94 days after CAR T cell injection). Control CAR T cell naive mice were simultaneously injected with OPM2 cells. Mice were not re-treated with CAR T cells. BCMA(171) CAR T cell previously treated long-term surviving mice were protected from OPM2 re-challenge and continued to have long-term survival. (D) Imaging from day 34 post-OPM2 re-challenge (day 130 overall) shows substantial MM burden in the CAR T cell naive injected mice and no OPM2 BLI signal in the previously treated mice (*p < 0.001).