CD38 and neoplasm: To determine whether sequential treatment of 225Ac-DOTA-CD38 TAT first followed by CS1 CAR T therapy would yield equivalent or better tumor growth inhibition and/or median survival compared to CS1 CAR T before TAT, we treated mice with disseminated MM with 7.4 kBg of 225Ac-DOTA-CD38 TAT followed by CS1 CAR T cell treatments at 14, 21 and 28 days post TAT.