bireociclib + fulvestrant

**Bireociclib (XZP-3287) is an oral small molecule inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6), developed by Xuanzhu Biopharmaceutical. It selectively inhibits CDK4 and CDK6, blocking phosphorylation of the retinoblastoma protein (Rb) in early G1 phase, thereby preventing cell cycle progression from G1 to S phase and inducing cell cycle arrest[1][2][3]. Fulvestrant is a selective estrogen receptor degrader (SERD) that binds to estrogen receptors and accelerates their degradation, leading to inhibition of estrogen signaling. The combination of bireociclib with fulvestrant is being investigated for the treatment of hormone receptor-positive (HR+), HER2-negative advanced or metastatic breast cancer in patients who have progressed on prior endocrine therapy[2][3][4]. Clinical trials have shown that this combination demonstrates superior efficacy compared to fulvestrant alone in this patient population with a manageable safety profile[2][4].**

Brand names

Xuanyuening

Other names

XZP-3287 + fulvestrantbireociclib + fulvestrant