Gemcitabine and docetaxel in metastatic breast cancer

Use of the gemcitabine (Gemzar) plus docetaxel (Taxotere) combination in metastatic breast cancer is motivated by the different mechanisms of action of the drugs, partially nonoverlapping toxicity profiles, and good single-agent activities of both drugs in treatment-naive and anthracycline-pretreated patients. In phase II trials, combinations of gemcitabine at 900 or 1,000 mg/m2 on days 1 and 8 and docetaxel at 75 to 100 mg/m2 on either day 1 or day 8 every 3 weeks, or gemcitabine at 800 mg/m2 on days 1, 8, and 15 and docetaxel at 35 mg/m2 on days 1, 8, and 15 or 100 mg/m2 on day 1 every 4 weeks, have produced response rates of 36% to 79% in patients receiving primarily second-line treatment; response rates were greater than 50% in five of six studies. In phase II trials using every-2-week regimens of gemcitabine at 1,500 or 2,000 mg/m2 on day 1 and docetaxel at 50 or 65 mg/m2 on day 1 or 55 mg/m2 on day 8, response rates were 50% in pretreated patients and 66% in treatment-naive patients. Neutropenia is the primary toxicity of the combination; in phase II studies performed with or without growth factor support, rates of grade 3/4 neutropenia ranged from 29% to 79% and rates of febrile neutropenia ranged from 0% to 18%. An ongoing phase III trial is comparing gemcitabine at 1,000 mg/m2 on days 1 and 8 plus docetaxel at 75 mg/m2 on day 1 every 21 days, vs capecitabine at 1,000 mg/m2 twice daily for 14 days plus docetaxel at 75 mg/m2 on day 1 every 21 days in patients with metastatic breast cancer. Results of this trial will help to determine optimal use of taxane-based combinations in patients with advanced disease.