This inducible gene expression system is based on a reverse Tet trans-activator fusion protein (rtTA), which activates the CAR gene transcription upon administration of doxycycline, and has been tested in multiple indications such as hepatocellular carcinoma (CD147 CAR), B cell malignancies (CD19 CAR), and multiple myeloma (CD38 CAR) [183,184,185]. This evidence concerns the gene CD19 and plasma cell myeloma.