Compositions and methods for CAR T cell therapy

A method of treating a patient for cancer, the method comprising

• i) administering to the patient a compound, or a pharmaceutically acceptable salt thereof, wherein the compound comprises a folate linked to fluorescein isothiocyanate (FITC) by a linker;
• ii) administering to the patient a chimeric antigen receptor T cell (CAR T cell) composition comprising CAR T cells comprising an anti-FITC antibody or fragment thereof;
• and
• iii) reducing or preventing cytokine release syndrome (CRS) or cytokine storm by administering to the patient a rescue agent which is a folate,
• wherein step iii) is performed after steps i) and ii), and
• wherein the cancer is a folate receptor-expressing cancer;
• whereupon the patient is treated for cancer.