Treatment patterns, effectiveness, and patient‐reported outcomes of palbociclib therapy in Chinese patients with advanced breast cancer: A multicenter ambispective real‐world study

BACKGROUND: Palbociclib was the only available cyclin‐dependent kinase 4/6 inhibitor in China until very recently, and its effect has not been systemically evaluated among Chinese patients. This study aims to assess the efficacy, safety and patient‐reported outcomes (PROs) of palbociclib plus endocrine therapy (ET) in real‐world China. METHODS: An ambispective cohort study was conducted on patients with advanced HR+HER2− breast cancer who received palbociclib between July 2018, and November 2020 and were enrolled from 12 hospitals. Treatment patterns, survival outcomes, and safety events were documented, and PROs (European Organization for Research and Treatment of Cancer Quality of Life Questionnaire‐Core 30 items [EORTC QLQ‐C30] and EuroQoL 5 dimensions [EQ‐5D]) were analyzed. The Kaplan–Meier method was used to visualize and estimate the median progression‐free survival (mPFS). Log‐rank tests, Cox regressions, t tests, and chi‐square tests were performed for comparison. RESULTS: A total of 190 patients (median follow‐up of 18.0 months) were enrolled. Palbociclib was mostly combined with aromatase inhibitors (66.3%), fulvestrant (32.6%), and tamoxifen (1.1%). The mPFS values were 21.0, 14.0, and 7.0 months with palbociclib administered in first‐ (n = 83), second‐ (n = 41) and subsequent‐line settings (n = 66), respectively. Endocrine sensitivity was significantly associated with patient prognosis (mPFS: 23.0, 12.0, and 6.0 months for endocrine naïve, acquired, and primary resistant patients, respectively, p < 0.01). The outcome was worse for patients who failed to meet the inclusion criteria of PALOMA‐3 than for those who met the criteria (later‐line: 6.0 months vs. 9.0 months). The most common adverse events (AEs) were neutropenia (74.2%; grade 3/4: 30.0%), fatigue (48.4%), anemia (32.6%), and thrombocytopenia (22.1%). PRO data suggested that palbociclib plus ET significantly improved cognitive and emotional function, pain symptoms, and overall quality of life. CONCLUSIONS: Palbociclib is effective for front‐line use and for treating endocrine‐sensitive patients in real‐world China and is generally well tolerated. The prevalence of AEs in the Chinese population is different from that reported in the PALOMA‐2/3 trials.