CD38 and neoplasm: Immunosuppressive cells, including MDSCs and B regs, showed increased CD38 expression, and daratumumab decreases the number of these cells. T regs, which showed increased CD38 expression, are more immunosuppressive and decreased following daratumumab. Daratumumab effect on T regs also have anti-tumor activity Observed changes were in ratios of CD8:CD4 and CD8: T regs with the treatment of daratumumab. But their exact contribution to the mechanism needs further evaluation and treatment.