GPRC5D⁺ cells are depleted from MM.1S tumors. (A-B) A repeat MM.1S study was conducted testing 1 dose (10 μg) of JNJ-64407564 and control bispecific antibodies. (A) Tumor and blood samples were analyzed on the day after dosing on days 16 and 19 for tumor-cell number by staining with anti-BCMA antibody (percent remaining human CD45⁺ and BCMA⁺ cells on the y-axis; first column) and T-cell activation (percent CD25⁺ and CD4⁺ or CD8⁺ T cells on the y-axis; remaining columns). The BCMA antibody was used as a second plasma-cell marker to avoid using a GPRC5D antibody in the ex vivo testing. (B) T-cell (CD3⁺, CD4⁺, CD8⁺; SP57, Ventana) infiltration within the tumors. For each section, the left panel is low magnification (1.5×) and the right panel is a higher magnification (10×).