A phase II trial of gemcitabine/carboplatin with or without trastuzumab in the first-line treatment of patients with metastatic breast cancer.

PURPOSE: The purpose of this study was to evaluate the efficacy and toxicity of the combination of gemcitabine and carboplatin (and with trastuzumab in patients with HER2-positive disease) as first-line treatment for patients with metastatic breast cancer (MBC).

PATIENTS AND METHODS: Seventy-four patients who had received no previous chemotherapy for MBC were enrolled. Patients with HER2-negative breast cancer received treatment with gemcitabine 1000 mg/m(2) intravenously (I.V.) on days 1 and 8 and carboplatin area under the curve (AUC) 5 I.V. on day 1. Cycles were repeated every 21 days. Patients with HER2-positive disease also received trastuzumab 8-mg/kg I.V. loading dose, then 6 mg/kg I.V. every 21 days. After the first 29 patients were treated, the carboplatin dose was lowered to AUC 4. Patients were re-evaluated every 6 weeks; responses were measured using Response Evaluation Criteria in Solid Tumors criteria.

RESULTS: In patients with HER2-negative disease, gemcitabine/carboplatin produced a 34% major response rate; an additional 28% of patients had stable disease > or = 6 months (overall disease control rate, 62%). Gemcitabine/carboplatin/trastuzumab produced an overall response rate of 66%, with a disease control rate of 77%. Grade 3/4 myelosuppression was common, even after reduction of the carboplatin dose. Only 3 patients treated with the lower dose regimen developed neutropenia and fever, but platelet and red blood cell transfusions were necessary in 24% and 40% of patients, respectively. Trastuzumab did not add to hematologic toxicity. Severe nonhematologic toxicity was uncommon.

CONCLUSION: Gemcitabine/carboplatin and gemcitabine/carboplatin/trastuzumab are active first-line regimens for patients with MBC. The gemcitabine/carboplatin combination causes more grade 3/4 myelosuppression than other standard combination regimens for MBC; however, severe nonhematologic toxicity is minimal.