MF-766, another potent and highly selective small-molecule inhibitor of the EP4 receptor, synergistically improved the efficacy of anti-PD-1 therapy in CT26 colon adenocarcinoma and EMT6 syngeneic mammary carcinoma mouse models through reduced G-MDSCs, induced M1-like macrophage reprogramming, as well as promoting the infiltration of CD8+ T cells, NK cells, and conventional dendritic cells (cDCs) in the TME (97). The gene discussed is PDCD1; the disease is breast carcinoma.