Targeting TREM2 on Tumor Associated Macrophages Enhances Efficacious Immunotherapy

Converting checkpoint inhibitor (CPI) resistant patients to responsive requires identifying novel suppressive mechanisms. We identified TREM2 + tumor associated macrophages (TAMs) as being correlated with exhausted CD8 + tumor infiltrating lymphocytes (TILs) in both mouse syngeneic tumor models and human solid tumors of multiple histological types. Fc-domain enhanced anti-TREM2 monoclonal antibody (mAb) therapy promoted anti-tumor immunity by elimination and modulation of TAM populations which led to enhanced CD8 + TIL infiltration and effector function. TREM2 + TAMs were most enriched in human ovarian cancer patients, where TREM2 expression corresponded to disease grade accompanied by worse recurrence-free survival. In an aggressive orthotopic ovarian cancer model, anti-TREM2 mAb therapy drove potent anti-tumor immunity. Together, these results highlight TREM2 as a highly attractive target for immunotherapeutic modulation in patients who are refractory to CPI therapy and likely have a TAM-rich tumor microenvironment.