In particular, CAR-T cells with higher frequency of Naïve and Stem Cell memory T cells, as well as with an higher CD4+/CD8+ ratio at time of leukapheresis, have been related with better antitumor activity and clinical responses in multiple myeloma (MM) and Chronic lymphoblastic leukemia (CLL) patients [10,12]. This evidence concerns the gene CD4 and plasma cell myeloma.