Phase II interventional study (N0337) of capecitabine in combination with vinorelbine and trastuzumab for first- or second-line treatment of HER2-positive metastatic breast cancer: A north central cancer treatment group trial

Background: We conducted a multiinstitutional phase II study of capecitabine in combination with vinorelbine and trastuzumab in patients eligible to receive first- or second-line treatment for human epidermal growth factor receptor type 2 (HER2)-positive (HER2⁺) metastatic breast cancer (MBC). Patients and Methods: The study was designed to test that the true confirmed response rate (CRR) was at most 45% vs. a true CRR of at least 65%. Between March 2005 and June 2008, eligible patients received capecitabine 825 mg/m² orally on days 1 to 14, vinorelbine 25 mg/m² intravenously on days 1 and 8 every 3 weeks, and trastuzumab 8 mg/kg intravenously on day 1 week 1 and 6 mg/kg every 3 weeks. The main outcome measure was CRR. Results: Of 47 women accrued, 45 were evaluable. This design required at least 25 confirmed responses in the 45 evaluable patients for the treatment to be considered promising. Thirty women (67%) achieved a confirmed response; 25 women (56%) had a confirmed partial response (PR); 5 women (11%) had confirmed complete responses (CRs). Median progression-free survival (PFS) was 11.3 months (95% confidence interval [CI], 8.4-16.7 months). Median overall survival was 28.5 months (95% CI, 24.8-36.4 months). Conclusions: This triplet combination demonstrated promising activity in patients with HER2⁺ MBC.