XUANZHUBIO-B (02575) has announced that it presented data on the effectiveness of palbociclib combined with letrozole or anastrozole for first-line treatment of HR+/HER2- advanced breast cancer during a poster session at the 2025 European Society for Medical Oncology (ESMO) in Germany on October 20, 2025. The BRIGHT-3 study is a randomized, double-blind Phase III clinical trial conducted at 58 centers in China, aimed at evaluating the efficacy and safety of palbociclib in combination with letrozole or anastrozole for this patient group. The study involved 397 patients with HR+/HER2- advanced breast cancer, of which 55.7% had visceral metastases and 41.3% were newly diagnosed with advanced disease. The median follow-up time was 20.7 months as of January 10, 2025.

The interim analysis indicates that, in terms of efficacy, the median progression-free survival (mPFS) for the palbociclib group has not yet been reached, while the control group's mPFS was 18.43 months and 19.55 months, respectively. The fact that the mPFS has not been reached suggests that more patients in the palbociclib group have not experienced disease progression, reflecting its lasting efficacy advantage. Compared to the placebo in combination with endocrine therapy, the palbociclib regimen can reduce the risk of disease progression or death by 47%, with a significant risk reduction of 64% observed in patients with poor prognoses and liver metastases, demonstrating outstanding potential in difficult-to-treat populations.

In the intention-to-treat population, the overall response rate (ORR) in the palbociclib group was 63.5%, significantly better than the control group's 42.5%. Regarding safety, the common adverse events associated with the palbociclib combination (such as diarrhea and neutropenia) were mostly grade 1-2 and manageable through supportive care or dose adjustments, indicating overall controllable safety. Following the interim data from the BRIGHT-3 study, the National Medical Products Administration of China officially accepted the new drug application for palbociclib combined with aromatase inhibitors for the treatment of HR+/HER2- advanced breast cancer on May 14, 2025. Palbociclib (brand name: XUANYUE NING), as a new type of CDK2/4/6 inhibitor, offers unique multi-target synergistic action mechanisms that robustly inhibit tumor cell proliferation and significantly reduce the hematological toxicity commonly associated with traditional CDK4/6 inhibitors. On May 13, 2025, palbociclib was approved by the National Medical Products Administration of China for use in combination with fulvestrant in patients who have progressed after prior endocrine treatment, marking it as the first and only CDK4/6 inhibitor approved in China for single-agent indication in patients who have experienced disease progression after two or more lines of endocrine therapy and chemotherapy.