Modakafusp alfa (TAK-573) is a humanized, anti-CD38 IgG4 monoclonal antibody fused to 2 attenuated IFNα2b molecules, which delivers interferon-alpha to CD38-expressing cells. Modakafusp alfa has direct anti-proliferative activity on multiple myeloma (MM) cancer cells in vitro and induces robust and durable antitumor responses in MM xenograft tumor models. Modakafusp alfa in combination with anti-PD-1 antibodies induces immunomodulation and antitumor responses with good tolerance in mice.