AMG 701 induced TDCC against MM cell lines in vitro. (A) Flow cytometry histograms depicting BCMA cell surface protein expression on cancer cell lines. Open graphs represent isotype staining; filled graphs represent BCMA protein staining. Numbers represent the number of BCMA molecules per cell. (B) Specific cytotoxicity of TDCC assays with BCMA protein-positive cell lines (L-363, MM1.R, MOLP-2, NCI-H929) or the BCMA protein-negative cell line (HCT-116) cocultured with human PBMCs at a 5:1 E:T ratio and increasing concentrations of AMG 701 for 48 hours. Data are mean ± standard deviation (SD) for 2 technical replicates. Curves are representative of 4 PBMC donors. Expression of CD69 (C) and CD25 (D) on T cells from TDCC assays of BCMA⁺ or BCMA⁻ cell lines or no target cells (PBMC), as described in panel B. Data are mean ± SD of 2 technical replicates representative of 4 PBMC donors. (E) Concentration of cytokines in supernatants of TDCC assays at the times indicated. Data represent 1 technical replicate from 1 PBMC donor. IFNγ, interferon-γ; IL-2, interleukin-2; MFI, mean fluorescence intensity; ND, not detectable; TNFα, tumor necrosis factor-α.