They tested this system in B cell malignancies and breast tumors by targeting CD19, CD22, and HER2 and demonstrated that these switchable CAR-T cells have potent antigen-specific and dose-dependent anti-tumor activity, providing an attractive way to improve the safety of CAR-T cell therapy in the clinic and suggesting that these switchable CAR-T cells could be applicable to a wide range of tumor antigens. This evidence concerns the gene CD19 and neoplasm.