Xuanzhu Biopharmaceutical Co., Ltd. (2575) recently presented interim Phase III clinical findings (BRIGHT-3 study) on Bireociclib in combination with letrozole or anastrozole for first-line treatment of HR+/HER2– advanced breast cancer at the European Society for Medical Oncology 2025 in Germany on October 20, 2025. The multicenter, double-blind trial enrolled 397 participants, with 55.7% having visceral metastases and 41.3% being newly diagnosed advanced cases.
As of January 10, 2025, the median follow-up time was 20.7 months. Median Progression-Free Survival in the Bireociclib cohort was not reached, whereas it was reported at 18.43 months and 19.55 months in the control group (based on investigator and independent review committee assessments, respectively). Bireociclib in combination with endocrine therapy reduced the risk of disease progression or death by 47% overall, rising to 64% in patients with liver metastases. An objective response rate of 63.5% was observed in the Bireociclib group compared with 42.5% in the control arm. Frequently seen adverse events, including diarrhea and neutropenia, were predominantly Grade 1 or 2 and deemed manageable.
On May 14, 2025, the National Medical Products Administration of China accepted the New Drug Application for Bireociclib combined with an aromatase inhibitor in HR+/HER2– advanced breast cancer. Previously, Bireociclib obtained approval on May 13, 2025, for use alongside Fulvestrant in endocrine-therapy-experienced patients and as a monotherapy option for those who had also received chemotherapy in the metastatic phase.
Bireociclib is a novel CDK2/4/6 inhibitor with a multi-target synergistic mechanism intended to suppress tumor cell proliferation while reducing hematological toxicity commonly associated with traditional CDK4/6 inhibitors. Xuanzhu Biopharmaceutical, as an innovative subsidiary of Sihuan Pharmaceutical Holdings Group Ltd., focuses on major diseases such as oncology, digestion, and non-alcoholic steatohepatitis. The company maintains both small-molecule and large-molecule R&D platforms, supporting a broad pipeline of potential therapies.