Gemcitabine, paclitaxel, and trastuzumab in metastatic breast cancer.

Gemcitabine (Gemzar) and paclitaxel show good activity as single agents and combined in metastatic breast cancer, and the combination of paclitaxel/trastuzumab (Herceptin) has been shown to prolong time to disease progression and survival significantly in this setting. Preclinical data indicate additive or synergistic effects of gemcitabine and trastuzumab in HER2-positive human breast cancer cell lines. In a phase II trial, patients with HER2-overexpressing metastatic breast cancer who had received no prior chemotherapy for metastatic disease received gemcitabine at 1,200 mg/m2 on days 1 and 8 and paclitaxel at 175 mg/m2 on day 1 every 21 days for six cycles plus trastuzumab at an initial loading dose of 4 mg/kg followed by 2 mg/kg weekly; patients without progressive disease after six cycles continued to receive trastuzumab until disease progression. Overall, objective response was observed in 28 (67%) of 42 evaluable patients, including complete response in 4 (10%) and partial response in 24 (57%); stable disease was observed in 7 (17%) and progressive disease was observed in 6 (14%). Median time to treatment failure was 9+ months. Median overall survival has not yet been reached, but is estimated at approximately 27 months. Significant toxicities apart from neutropenia were uncommon. The triplet combination of gemcitabine, paclitaxel, and trastuzumab is highly active and well tolerated in patients with HER2-overexpressing metastatic breast cancer.