ONO-4578 + letrozole + palbociclib

This is an investigational **combination therapy** composed of **ONO-4578**, a highly selective prostaglandin E2 receptor EP4 antagonist, **letrozole**, an aromatase inhibitor, and **palbociclib**, a cyclin-dependent kinase 4/6 inhibitor. The regimen is being studied as first-line endocrine therapy in postmenopausal patients with metastatic or recurrent hormone receptor-positive, HER2-negative breast cancer. ONO-4578 works by blocking EP4 signaling, which plays a role in immunosuppression within the tumor microenvironment, potentially enhancing antitumor immune responses. Letrozole reduces estrogen production to inhibit hormone-driven cancer growth. Palbociclib inhibits CDK4/6, which prevents cell cycle progression and tumor proliferation[1][2][4].

Other names

letrozolepalbociclib