In an open-label, randomized, phase 3 trial, we compared the efficacy and safety of paclitaxel with that of paclitaxel plus bevacizumab, a monoclonal antibody against vascular endothelial growth factor, as initial treatment for metastatic breast cancer.

We randomly assigned patients to receive 90 mg of paclitaxel per square meter of body-surface area on days 1, 8, and 15 every 4 weeks, either alone or with 10 mg of bevacizumab per kilogram of body weight on days 1 and 15. The primary end point was progression-free survival; overall survival was a secondary end point.

From December 2001 through May 2004, a total of 722 patients were enrolled. Paclitaxel plus bevacizumab significantly prolonged progression-free survival as compared with paclitaxel alone (median, 11.8 vs. 5.9 months; hazard ratio for progression, 0.60; P<0.001) and increased the objective response rate (36.9% vs. 21.2%, P<0.001). The overall survival rate, however, was similar in the two groups (median, 26.7 vs. 25.2 months; hazard ratio, 0.88; P=0.16). Grade 3 or 4 hypertension (14.8% vs. 0.0%, P<0.001), proteinuria (3.6% vs. 0.0%, P<0.001), headache (2.2% vs. 0.0%, P=0.008), and cerebrovascular ischemia (1.9% vs. 0.0%, P=0.02) were more frequent in patients receiving paclitaxel plus bevacizumab. Infection was more common in patients receiving paclitaxel plus bevacizumab (9.3% vs. 2.9%, P<0.001), but febrile neutropenia was uncommon (<1% overall).

Initial therapy of metastatic breast cancer with paclitaxel plus bevacizumab prolongs progression-free survival, but not overall survival, as compared with paclitaxel alone. (ClinicalTrials.gov number, NCT00028990.)