YY001

YY001 is an orally bioavailable, selective small molecule antagonist of the prostanoid EP4 receptor (PTGER4), developed by Shanghai Yuyao Biotech. The EP4 receptor is a key mediator of prostaglandin E2 (PGE2) signaling within the tumor microenvironment, where it promotes immunosuppression by driving the differentiation and function of myeloid-derived suppressor cells (MDSCs) and inhibiting the activity of cytotoxic T lymphocytes and natural killer cells. By selectively blocking EP4, YY001 aims to remodel the immune microenvironment, enhance T-cell infiltration, and restore anti-tumor immunity. It is currently being investigated for the treatment of advanced solid tumors, including colorectal, gastric, and prostate cancers, both as a monotherapy and in potential combination with immune checkpoint inhibitors such as PD-1 antibodies.