Multifactorial mechanism of action of daratumumab. Daratumumab induces antimyeloma effects via multiple mechanisms of action. Based on the present study, an additional mechanism of action is proposed in which treatment with daratumumab eliminates a population of highly immunosuppressive CD38⁺ Tregs, T-cell MDSCs, and Bregs and thus stimulates T-cell effector functions. DARA, daratumumab.