Metronomic oral combination chemotherapy with capecitabine and cyclophosphamide: a phase II study in patients with HER2-negative metastatic breast cancer

Purpose Metronomic combination chemotherapy with the oral fluoropyrimidine doxifluridine/5′-deoxy-5-fluorouridine (5 -DFUR) and oral cyclophosphamide (C) showed promising efficacy in a single-arm study. The oral fluoropyrimidine capecitabine was designed to deliver 5-fluorouracil preferentially to tumors, potentially improving efficacy over doxifluridine. We conducted a phase II multicenter study to evaluate an all-oral XC combination in patients with HER2-negative metastatic breast cancer (MBC). Materials and methods Patients received capecitabine 828 mg/m2 twice daily with cyclophosphamide 33 mg/m2 twice daily, days 1–14 every 3 weeks. The primary endpoint was overall response rate (ORR). Secondary endpoints included progression-free survival (PFS), overall survival (OS), and safety. Results Between May 2007 and April 2009, 51 patients were enrolled and 45 were included in the efficacy analysis. The median follow-up was 18.1 months. ORR was 44.4% and stable disease (≥24 weeks) was achieved in 13.4%, resulting in a 57.8% clinical benefit response rate. Median PFS was 12.3 months (95% confidence interval: 8.9–18.9 months). Median PFS was 10.7 months in triple-negative disease and 13.2 months in estrogen-receptor positive, HER2-negative disease. The 1- and 2-year OS rates were 86 and 71%, respectively. Median OS has not been reached. Grade 3 adverse events comprised leukopenia (26%), neutropenia (16%), and decreased hemoglobin (2%). There was no grade 3 hand-foot syndrome. Conclusions Oral XC is an effective first- or second-line therapy for MBC, demonstrating high activity in both luminal A and triple-negative disease with few severe side effects. This metronomic oral combination chemotherapy could be beneficial for the treatment of HER2-negative MBC.