To evaluate cytotoxic activity in the presence of TGF-β–mediated immunosuppression, using levels estimated from the prostate cancer bone TME (13), 40A3Bz cells and 40A3Bz dnTGFβRII CAR-Ts were cocultured with STEAP2-expressing C4-2 cells in the presence of 30 ng/mL TGF-β. Here, STEAP2 is linked to prostate cancer.