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Standard weekly paclitaxel offered greater benefit than newer, costlier treatments
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CHICAGO — Weekly first-line chemotherapy with either of two newer, more expensive drugs offered no additional benefit than standard weekly paclitaxel for patients with locally advanced or metastatic breast cancer, according to results of a phase 3 randomized trial.
Patients treated with standard weekly paclitaxel demonstrated longer PFS than those treated with ixabepilone (Ixempra, Bristol-Myers Squibb) and nab-paclitaxel (Abraxane, Abraxis BioScience), both of which are FDA-approved treatments in this setting. Patients randomly assigned to paclitaxel also reported fewer toxicities than those treated with nab-paclitaxel, researchers said.
“In metastatic breast cancer, we are constantly examining and refining dosing schedules, testing new therapies and looking closely at molecular characteristics of patients’ tumors to find the right treatment for the right patient with the fewest toxicities,” Hope S. Rugo, MD, professor of medicine and director of breast oncology and clinical trials at the University of California, San Francisco, Helen Diller Family Comprehensive Cancer Center, said in a press release. “This study demonstrates that we should not simply assume that newer drugs are always better than the standard therapies.”
Researchers designed the NCI-supported cooperative group trial on the hypothesis that the novel agents would provide superior efficacy to standard weekly paclitaxel.
Rugo and colleagues enrolled 799 patients with chemotherapy-naive metastatic breast cancer. They were randomly assigned to one of three therapies — paclitaxel 90 mg/m2 (n=283), nab-paclitaxel 150 mg/m2 (n= 271) or ixabepilone 16 mg/m2 (n=245). Each cycle consisted of once-a-week treatment for 3 weeks, followed by a 1-week break.
Ninety-eight percent of patients also received bevacizumab (Avastin, Genentech).
Patients could discontinue chemotherapy and continue with bevacizumab alone after six cycles if they were stable or had responding disease to reduce toxicity and maintain quality of life, Rugo said during a press conference.
The primary endpoint was PFS, and median follow-up for all surviving patients was 12 months.
Median PFS was 10.6 months for patients assigned to paclitaxel vs. 9.2 months for those assigned to nab-paclitaxel and 7.6 months for those assigned to ixabepilone (HR=1.19; 95% CI, 0.96-1.49 for nab-paclitaxel vs. paclitaxel; HR=1.53; 95% CI, 1.24-1.9 for ixabepilone vs. paclitaxel).
Patients in the paclitaxel arm experienced fewer grade-3/grade-4 sensory neuropathy (16% vs. 25% for the nab-paclitaxel and ixabepilone arms) and other non-hematologic toxicities. Patients in the nab-paclitaxel arm reported the highest rates of grade-3/grade-4 hematologic toxicities (51% vs. 21% for the paclitaxel arm and 12% for the ixabepilone arm).
Sensory neuropathy, a secondary endpoint of the trial, was greater in both experimental arms compared with paclitaxel.
The researchers are awaiting the results of correlative studies designed to determine whether subsets of patients who have tumors with certain molecular characteristics benefit more from one of the treatments.
For more information:
Rugo HS. #CRA1002. Presented at: the 2012 American Society of Clinical Oncology Annual Meeting; June 1-5, 2012; Chicago.
Disclosure: The researchers report serving as a consultant or adviser for, and receiving research funding or honoraria from, Abraxis BioScience, Bristol-Myers Squibb, Celgene and Genentech/Roche.