Together, these results suggest that CD84 plays a key role in regulating the function of MDSCs during MM progression, and its blockade can reduce the number of tumor cells and their immunosuppressive properties, even after the MM tumor has already been established; this renders CD84 an attractive target to treat immunosuppression, leading to an increase in the T cell–mediated antitumor response in MM. The gene discussed is CD84; the disease is neoplasm.