PURPOSE: The oral fluoropyrimidine carbamate, capecitabine, is a highly active and well-tolerated treatment for metastatic breast cancer. In patients treated previously with anthracyclines and taxanes, capecitabine is an approved single-agent therapy. Trastuzumab, a monoclonal antibody targeting the human epidermal growth factor receptor 2 (HER-2), is also highly active in HER-2-overexpressing breast cancer. We have conducted a phase II study to confirm activity and feasibility of capecitabine and trastuzumab in combination in HER-2-overexpressing advanced/metastatic breast cancer. PATIENTS AND METHODS: Twenty-seven patients with HER-2-overexpressing metastatic breast cancer previously treated with anthracyclines and/or taxanes received oral capecitabine 1,250 mg/m(2) bid for 14 days followed by a 7-day rest period combined with intravenous trastuzumab 4 mg/kg body weight on day 1 (loading dose) followed by 2 mg/kg weekly. RESULTS: Capecitabine/trastuzumab treatment achieved objective responses in 12 patients (45%), including complete response in four patients (15%) and partial response in eight patients (30%). Disease was stabilized in an additional nine patients (33%). The median overall survival time was 28 months, and the median progression-free survival time was 6.7 months. The safety profile of the combination was favorable and predictable, with a low incidence of grade 3/4 adverse events. The most common adverse events were pain, hand-foot syndrome, and GI toxicities. Severe myelosuppression was rare and severe alopecia did not occur. CONCLUSION: These data confirm that the combination of capecitabine and trastuzumab is highly active in patients with HER-2-overexpressing anthracycline- and/or taxane-pretreated breast cancer, with only slight restrictions regarding quality of life.