[Clinical observation of palbociclib combined with endocrine therapy in hormone receptor positive and HER2 negative advanced breast cancer].

Objective: To analyze the application, efficacy, and safety of palbociclib in hormone receptor positive (HR+) and HER2 negative (HER2-) advanced breast cancer in the real world. Methods: The information of patients who received palbociclib treatment from September 2018 to September 2020 was collected, and the general medical history data and disease characteristics were summarized. The objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), time to treatment failure (TTF), and safety were analyzed. Results: A total of 55 patients with HR+/HER2-advanced breast cancer who received a treatment regimen containing palbociclib were enrolled. The ORR was 48.8%, and DCR was 88.4%. The median PFS was 12.0 months (95%CI, 11.1-13.0 months), and the median TTF was 8.50 months (95%CI, 2.5-14.5 months). Among them, palbociclib was superior to multi-line therapy in the first line (P=0.000 1). The prognosis of patients with non-liver metastases was better (P=0.01). Hematological toxicity was the focus of observation of adverse events, including leukopenia, neutropenia, and thrombocytopenia. The incidence rates of them were 78.2%, 85.5%, and 34.5%, respectively. No other grade 3-4 nonhematological toxicity was found. Conclusions: Palbociclib combined with endocrine therapy in patients with HR+/HER2-advanced breast cancer has good efficacy and controllable adverse reactions. It can be used as a first-line or multi-line treatment option for HR+/HER2-advanced breast cancer.