Dalpiciclib With Endocrine Therapy for Advanced Breast Cancer After CDK4/6 Inhibitor Failure (DAWNA-FES)

"* Dalpiciclib: 150 mg, orally, once daily, on days 1-21, every 28 days (3 weeks on, 1 week off)~* Letrozole: 2.5 mg, orally, once daily (continuous), every 28 days OR Anastrozole: 1.0 mg, orally, once daily (continuous), every 28 days OR Exemestane: 25 mg, orally, once daily (continuous), every 28 days OR Fulvestrant: 500 mg, intramuscular injection on day 1/15 of the first cycle, then on day 1 of each subsequent cycle, every 28 days OR Tamoxifen: 10-20 mg, orally, twice daily (continuous), every 28 days~* Pre/perimenopausal women also require ovarian function suppression (OFS), which can be achieved through bilateral oophorectomy or the use of gonadotropin-releasing hormone (GnRH) analog drugs"

The chemotherapy regimen is chosen by the clinical physician and may include, but is not limited to, the following options: the combination of paclitaxel and capecitabine, the combination of paclitaxel and carboplatin, single-agent capecitabine, single-agent platinum drugs, and the combination of gemcitabine and platinum-based chemotherapy. Each treatment cycle consists of a 21-day duration.