Isatuximab is a monoclonal antibody targeting the transmembrane receptor and ectoenzyme CD38, a protein highly expressed on hematological malignant cells, including those in multiple myeloma (MM). Isatuximab has antitumor activity via multiple biological mechanisms, including antibody-dependent cellular-mediated cytotoxicity, complement-dependent cytotoxicity, antibody-dependent cellular phagocytosis, and direct induction of apoptosis without crosslinking. Isatuximab also directly inhibits CD38 ectoenzyme activity, which is implicated in many cellular functions.