CAR-iNKTs and CAR-ML NK cells have lower CRS potential compared with CAR-Ts. (A) Schema of CRS assay. (B) Killing by M-BB BCMA CAR-Ts, CAR-iNKTs, and CAR-ML NK cells using MM.1S-CG target cells (left); levels of secreted IL-6 (right). Secreted IL-6 levels shown are from cultures at the lowest E:T ratio at which killing was 100% by all effector cell types (most often 0.5:1). All CRS killing and IL-6 assays were performed in duplicate. (C) Similar CRS killing as in panel B but in an independent experiment using cells from a separate donor. Killing (left) and secreted IL-6 levels (right). (D) Three separate CRS experiments comparing M-BB BCMA CAR-Ts and M-BB BCMA CAR-iNKTs and MM.1S target cells. (E) CRS assays comparing BCMA CAR-Ts (EF-1α-BCMA-41BB) and CAR-iNKTs using MM.1S-CG targets or (F) OPM2-CG target cells. (G) Killing (left) and secreted IL-6 (right) using CD19 CAR-Ts, CD19 CAR-iNKTs (EF-1α-CD19-CD28 4-1BB), and NALM-CG target cells, which endogenously express CD19. (H) (Left) Killing efficiency at the 0.5:1 E:T ratio was similar for all BCMA CAR samples. Minimal effect of rhIL-7-hyFc on IL-6 levels in CRS assays. ELISA, enzyme-linked immunosorbent assay.