Targeting CD47 as a Novel Immunotherapy for Multiple Myeloma.

Multiple myeloma (MM) remains to be incurable despite recent therapeutic advances. CD47, an immune checkpoint known as the "don't eat me" signal, is highly expressed on the surface of various cancers, allowing cancer cells to send inhibitory signals to macrophages and impede phagocytosis and immune response. In this study, we hypothesized that blocking the "don't eat me" signaling using an anti-CD47 monoclonal antibody will induce killing of MM cells. We report that CD47 expression was directly correlated with stage of the disease, from normal to MGUS to MM. Moreover, MM cells had remarkably higher CD47 expression than other cell populations in the bone marrow. These findings indicate that CD47 is specifically expressed on MM and can be used as a potential therapeutic target. Further, blocking of CD47 using an anti-CD47 antibody induced immediate activation of macrophages, which resulted in induction of phagocytosis and killing of MM cells in the 3D-tissue engineered bone marrow model, as early as 4 hours. These results suggest that macrophage checkpoint immunotherapy by blocking the CD47 "don't eat me" signal is a novel and promising strategy for the treatment of MM, providing a basis for additional studies to validate these effects in vivo and in patients.

Déclaration de conflit d'intérêts

Dr. Azab received research support from Vasculox Inc. to conduct this study. He also received funding from GlycoMimetic Inc.; however, this has no contribution to this study. In addition, Dr. Azab is the founder and owner of Cellatrix LLC that has an exclusive license for the 3DTEBM technology described in part of the experiments in this paper. Moreover, Dr. Azab is the founder and owner of Targeted Therapeutics LLC; however, this has no contribution to this study. Other authors state no conflicts of interest.