A variety of small molecules such as FITC-conjugated antibodies, rapamycin, folate, rimiducid, proteolysis-targeting chimera (PROTAC), and dastinib have been employed to develop safety switches for CAR-T cells (115) Switchable CAR-Ts approach in breast cancer treatment using Her2-targeted antibody drug combination with a T cell-redirected bsAb, and a FITC-modified antibody capable of redirecting anti-FITC CAR-T (switchable CAR-T; sCAR-T) cells showed improved activity against cancer cells (116). Here, ERBB2 is linked to cancer.