CD38 and neoplasm: Through Fc-receptor-dependent mechanisms, daratumumab recruits the immune system and eliminates CD38-expressing tumor cells via a broad spectrum of mechanisms (Figure 2), including complement-dependent cytotoxicity (CDC) [41], antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), induction of apoptosis [42,43], and an indirect immune modulatory effect moderated by the depletion of suppressive CD38+ regulatory T cells [44].