Fulvestrant versus capecitabine as maintenance therapy in hormone receptor-positive, HER2-negative metastatic breast cancer after first-line chemotherapy (FAMILY): a multicenter, open-label, randomized, phase 3 trial

Maintenance therapy is key in prolonging remission and improving quality of life for hormone receptor-positive (HR + ), HER-2 negative (HER2-) metastatic breast cancer (MBC), but optimal strategies remain debated. This multicenter, open-label, randomized phase 3 trial conducted across 22 hospitals in mainland China (ClinicalTrials.gov, NCT04263298; Chinadrugtrials.org.cn, ChiCTR-IIR-17014036) compared the efficacy and safety of fulvestrant versus capecitabine as maintenance therapy in HR + /HER2- MBC patients after achieving objective response or disease control following first-line chemotherapy. The primary end point was investigator-assessed progression-free survival (PFS). A total of 210 patients underwent randomization, with 105 assigned to each group. As of the data cutoff date on March 1, 2025, the median follow-up was 33.6 months (range 1.5-81.1). Median PFS favored fulvestrant compared with capecitabine (17.3 months [95% CI 12.7-23.3] vs. 9.0 months [95% CI 7.5-14.3]; hazard ratio 0.63, 95% CI 0.47-0.99; p = 0.003). Overall survival data were not yet mature. Grade ≥3 adverse events (AEs) occurred in three patients (2.9%) in the fulvestrant group and 11 (10.5%) in the capecitabine group. Treatment discontinuation due to AEs occurred in 0% and 7.6% of patients, respectively. Fulvestrant maintenance therapy significantly improves PFS compared to capecitabine in HR + /HER2- MBC patients achieving objective response or disease control following first-line chemotherapy, with a favorable safety profile.