Figure 6.

Different kinetics of T-cell activation and cytokine production in BCMAxCD3 bsAb– and BCMA CAR T-cell–treated animals. NSG mice were implanted intravenously with OPM-2-Luc tumors, engrafted with PBMCs, and treated on day 21 with either BCMAxCD3 bsAb or CD3-binding control bsAb (0.4 mg/kg) as in Figure 5C, or control CAR T cells or BCMA CAR T cells (2 × 10⁶ CAR⁺ cells) as in Figure 5D. Mice were bled at various time points after dosing to measure serum cytokines, and femurs were harvested (2 femurs pooled from each mouse) and assessed by immunofluorescence staining with flow cytometry analysis. n = 5 mice per group. (A) Values represent mean ± SEM serum concentrations of human IFN-γ at 4 hours, 3 days, and 7 days after dosing. (B) Values represent mean ± SEM absolute numbers of total T cells (left panel) or CAR⁺ T cells (right panel) from 2 pooled femurs from each mouse at the indicated time point after dosing. (C-D) Values represent individual frequencies of CD25⁺ (C) and 4-1BB⁺ (D) cells among total T cells from bsAb-treated mice (left graphs), and CAR^– or CAR⁺ T cells from BCMA CAR T-cell–treated mice (right graphs). (E) Values represent individual mean fluorescence intensity (MFI) of intracellular granzyme B expression by total T cells from bsAb-treated mice (left graphs) and CAR^– or CAR⁺ T cells from BCMA CAR T-cell–treated mice (right graphs). Bars indicate mean ± SEM values. Significant values determined by the Mann-Whitney test are indicated: *P < .05 and **P < .01 compared with control-treated animals at the indicated time point.