Treatment with Combinations of the Anti-HER2 Antibody Trastuzumab and Capecitabine in Advanced Metastatic Breast Cancer Patients – a Pilot Study

Background: Metastatic HER2-overexpressing breast cancer patients mostly are intensively pretreated patients. Tumor progression requires an effective and well tolerated treatment. Here, we report of a study with capecitabine/trastuzumab combination therapy, with regard to tumor response and safety in advanced metastatic breast cancer overexpressing HER2. Patients and Methods: A cohort of 20 metastatic patients suffering from HER2-overexpressing carcinoma were treated with capecitabine/trastuzumab. The patients had progressive disease after taxane/trastuzumab combination therapy. All patients received a standard dose of capecitabine 1,250 mg/m2 twice daily, administered on days 1-14, combined with 2 mg/kg weekly trastuzumab. Trastuzumab treatment was continued from previous treatment regimens. Safety and tolerability of this regimen were evaluated. Results: Response rate and time to progression were documented. The median number of treatment cycles was 10 (range: 3-18). The median dose of capecitabine was 2,100 mg/m2 daily. 2 patients were reported to have complete response, 6 partial response, and 5 stable disease. 7 patients had progressive disease. Median time to progression was 30 weeks. The treatment was well tolerated with little side effects. Only palmar-plantar erythema and gastrointestinal disorders required dose reductions. Conclusion: Combination of capecitabine/trastuzumab is an effective and safe regimen in pretreated HER2-positive metastatic breast cancer. Our results comfirm preclinical observations of an at least additive effect of HER2 antibody treatment with capecitabine.