Phase II study of weekly docetaxel alone or in combination with trastuzumab in patients with metastatic breast cancer.

This study was designed to determine the efficacy and toxicity of weekly docetaxel in metastatic breast cancer when given alone (for HER2/neu negative disease) or with trastuzumab (for HER2/neu overexpressing disease). Patients with metastatic breast carcinoma received docetaxel given on 2 different schedules (group 1A, 33 mg/m2 weekly [n = 21]; group 1B, 40 mg/m2 weekly for 3 weeks with 1 week off [n = 14]). Patients with HER2/neu overexpressing disease also received trastuzumab 4 mg/kg on day 1, then 2 mg/kg on days 8 and 15 of each 28-day cycle (group 2). Fifty-two patients were treated with docetaxel alone (group 1A/B, n = 35) or in combination with trastuzumab (group 2, n = 17). Prior taxane therapy given every 3 weeks had been used for metastatic disease in 19 of 35 patients (54%) in group 1A/B and in 2 of 17 patients (12%) in group 2. The mean delivered dose intensity of docetaxel was 29 mg/m2 per week. Partial response occurred in 7 of 35 patients (21%; 95% exact binomial confidence interval [CI], 9%-38%) treated with docetaxel alone, including 3 of 19 taxane-pretreated patients (16%) and 4 of 16 taxane-naive patients (25%). Partial response occurred in 10 of 17 patients (59%; 95% CI, 34%-82%) treated with docetaxel/trastuzumab. The most common grade 3/4 toxicities, occurring in more than or equal to 10% of patients, included neutropenia (21%), pulmonary toxicity (12%), and hyperglycemia (10%). The median times to disease progression were 4.5 months (95% CI, 2.5-6.5 months) in the docetaxel group and 8.5 months (95% CI, 4.5-12.5 months) in the docetaxel/trastuzumab group. Weekly docetaxel/trastuzumab is an effective regimen for patients with HER2/neu overexpressing metastatic breast cancer. Weekly docetaxel may be effective in as many as 20% of patients who had progressive disease after treatment with taxanes given every 3 weeks.