UCSF

Purpose

We compared nab-paclitaxel or ixabepilone once per week to paclitaxel with bevacizumab as first-line therapy for patients with advanced breast cancer (BC) to evaluate progression-free survival (PFS) for nab-paclitaxel or ixabepilone versus paclitaxel.

Patients and methods

Eligible patients were age ≥ 18 years with chemotherapy-naive advanced BC. Patients were randomly assigned to bevacizumab with paclitaxel 90 mg/m(2) (arm A), nab-paclitaxel 150 mg/m(2) (arm B), or ixabepilone 16 mg/m(2) (arm C), once per week for 3 of 4 weeks. Planned enrollment was 900 patients, which would give 88% power to detect a hazard ratio of 0.73.

Results

In all, 799 patients were enrolled, and 783 received treatment (97% received bevacizumab). Arm C was closed for futility at the first interim analysis (n = 241), and arm A (n = 267) and arm B (n = 275) were closed for futility at the second interim analysis. Median PFS for paclitaxel was 11 months, ixabepilone was inferior to paclitaxel (PFS, 7.4 months; hazard ratio, 1.59; 95% CI, 1.31 to 1.93; P < .001), and nab-paclitaxel was not superior to paclitaxel (PFS, 9.3 months; hazard ratio, 1.20; 95% CI, 1.00 to 1.45; P = .054). Results were concordant with overall survival; time to treatment failure was significantly shorter in both experimental arms v paclitaxel. Hematologic and nonhematologic toxicity, including peripheral neuropathy, was increased with nab-paclitaxel, with more frequent and earlier dose reductions.

Conclusion

In patients with chemotherapy-naive advanced BC, ixabepilone once per week was inferior to paclitaxel, and nab-paclitaxel was not superior with a trend toward inferiority. Toxicity was increased in the experimental arms, particularly for nab-paclitaxel. Paclitaxel once per week remains the preferred palliative chemotherapy in this setting.