Immune Profiles of Myeloma Tumor Microenvironment May Predict Sensitivity or Resistance to Elotuzumab

Background: Elotuzumab (ELO), an immunobiologic therapy targeting SLAMF7/CD319, is effective in the treatment of multiple myeloma (MM) with clinical indications in relapsed/refractory disease in combination with lenalidomide or pomalidomide. ELO binds SLAMF7 on the surface of MM cells to increase immune recognition while also binding SLAMF7 on NK cells resulting in the activation of an effector cell population capable of readily killing via antibody-dependent cellular cytotoxicity (ADCC) mechanisms. ELO efficacy has also been linked to enhanced antibody-dependent cellular phagocytosis (ADCP). Given the dependence of ELO activity on immune elements of the tumor microenvironment (TME), we hypothesized that characterization of the immunologic constituents of the immune TME (iTME) would provide cues capable of predicting clinical efficacy.