Phase II trial of trastuzumab followed by weekly paclitaxel/carboplatin as first-line treatment for patients with metastatic breast cancer

Abstract

Purpose: To determine the response rate of trastuzumab as first-line therapy in patients with HER-2 overexpressing metastatic breast cancer. To assess the feasibility and toxicity of weekly paclitaxel/carboplatin with or without trastuzumab following initial treatment with trastuzumab.

Patients and methods: Sixty-one patients received trastuzumab (8 mg/kg followed by 4 mg/kg/wk) for 8 weeks. Responding patients received 8 additional weeks of trastuzumab (4 mg/kg/wk), and then proceeded to receive trastuzumab (2 mg/kg) in combination with paclitaxel 70 mg/m(2) and carboplatin (area under the curve, 2) weekly for 6 weeks followed by 2 weeks rest. Stable patients after the initial 8 weeks of trastuzumab proceeded to treatment with trastuzumab, paclitaxel, and carboplatin. Patients with disease progression during the initial 8 weeks had the trastuzumab discontinued and were treated with weekly paclitaxel/carboplatin.

Results: Weekly paclitaxel/carboplatin with or without trastuzumab was well tolerated. Fifty-two patients were assessable for response and all 61 patients were assessable for survival. Seventeen (33%) of 52 patients experienced a minor/partial response to single-agent trastuzumab and received 8 additional weeks of single-agent trastuzumab. Fifteen (29%) of 52 patients had stable disease and proceeded to receive paclitaxel/carboplatin/trastuzumab. Thirty-one patients with measurable disease were assessable for response after initial single-agent trastuzumab followed by paclitaxel/carboplatin/trastuzumab. An overall response rate of 84% (eight complete responses/18 partial responses), median time to progression of 14.2 months, and median overall survival of 32.2 months was reported with the triplet combination. In the patients treated with paclitaxel/carboplatin alone after disease progression on initial single-agent trastuzumab, an overall response rate of 69% (one complete response/10 partial responses), median time to progression of 8.3 months, and median overall survival of 22.2 months was reported. Median time to progression for all 61 patients is 10 months and the median overall survival is 26.7 months.

Conclusion: This trial confirms the activity and tolerability of weekly paclitaxel/carboplatin alone or in combination with trastuzumab in women with HER-2 overexpressing metastatic breast cancer.