These findings also indicate that FAP acts as a physical or chemical shield for PSCA‐positive cells, yet it remains a promising target for cancer therapy,[25, 63] despite the unclear mechanisms of sFAP formation.[40] With an increased fraction of FAP‐expressing cells in the 3D multi‐spheroid model, reduced cell killing efficacy and cytokine production were observed, while cell killing remained effective under 2D culture conditions. Here, FAP is linked to cancer.