Weekly Gemcitabine and Trastuzumab in the Treatment of Patients With HER2-Overexpressing Metastatic Breast Cancer

Background: The use of trastuzumab in combination with either a taxane or vinorelbine has improved the efficacy of treatment for women with HER2-positive (HER+) breast cancer. We investigated the activity and toxicity of the gemcitabine/trostuzumab combination as first- or second-line treatment in women with HER2+ metastatic breast cancer (MBC). Patients and Methods: Forty-one women with HER2+ MBC were treated with gemcitabine 1000 mg/m(2) intravenously (I.V.) days 1, 8, and 15 and trastuzumab 4-mg/kg I.V loading dose and then 2 mg/kg weekly. Cycles were repeated every 28 days. Patients were evaluated after 8 weeks of treatment; responders/stable patients continued treatment until progression. Results: Patients received a median of 28 weeks of treatment. Eleven of 37 evaluable patients (30%; 95% Cl, 17%-46%) had major responses. The median progression-free survival (PFS) was 4 months (95% Cl, 1.9-5.3 months), with a 1 year PFS of 17%. Four of 15 patients (27%) who had previously received trastuzumab for MBC had partial responses. The gemcitabine/trastuzumab combination was well tolerated. Conclusion: The combination of gemcitabine and trastuzumab is an active regimen but appears less active than trastuzumab in combination with either taxanes or vinorelbine. The role of gemcitabine/trastuzumab (versus gemcitabine alone) in women who have already received a trastuzumab-containing regimen for HER2+ MBC is not defined by this study.