NS-161

NS-161 is an orally active small molecule antagonist of the Prostaglandin E2 (PGE2) receptor 4 (EP4), currently under development by Nippon Shinyaku. It is primarily being investigated for the treatment of endometriosis. PGE2 is a key mediator of inflammation and pain, and its effects are largely mediated through four G-protein coupled receptors (EP1-4). EP4 signaling is specifically implicated in the proliferation of endometriotic lesions and the associated inflammatory pain. By selectively antagonizing the EP4 receptor, NS-161 is designed to provide a non-hormonal therapeutic option for managing endometriosis symptoms. Clinical development is currently in Phase 1, focusing on safety, pharmacokinetics, and tolerability in healthy volunteers and target populations.