Eribulin mesylate failed to show a statistically significant survival benefit compared with capecitabine in women with previously treated metastatic breast cancer.
Peter A. Kaufman, MD
Eribulin mesylate failed to show a statistically significant survival benefit compared with capecitabine in women with previously treated metastatic breast cancer in a phase III trial reported at the 2012 CTRC-AACR San Antonio Breast Cancer Symposium. Eribulin achieved similar progression-free survival (PFS) and overall survival (OS) as capecitabine, and failed to show superiority over capecitabine, a widely used drug to treat metastatic breast cancer.
On the positive side, this is the first study to demonstrate activity of eribulin in the first-, second-, and third-line setting in metastatic breast cancer, according to lead author Peter A. Kaufman, MD, Associate Professor of Medicine at the Geisel School of Medicine at Dartmouth and the Norris Cotton Cancer Center in Lebanon, New Hampshire.
“The study objectives were not met,” Kaufman said. “Although we didn't show a statistically significant superiority over capecitabine, which was our goal, numerically the overall survival with eribulin was better than with capecitabine.”
Additionally, subgroup data suggested that eribulin improved survival by about 5 months in patients with triple negative breast cancer versus capecitabine, and this line of study will be pursued further, Kaufman said.
Eribulin — a non-taxane microtubule dynamics inhibitor – was approved in 2010 by the FDA for the treatment of metastatic breast cancer previously treated with an anthracycline and a taxane in either the adjuvant or metastatic setting and at least 2 cytotoxic chemotherapy treatment regimens for the treatment of metastatic disease. Approval was based on a statistically significant improvement in OS when it was compared with several different treatments currently used to treat the disease.
The present study evaluated use of eribulin versus capecitabine in earlier lines of treatment of metastatic breast cancer. The study randomized 1102 patients in a 1:1 ratio receive either eribulin mesylate 1.4 mg/m2 given on days 1 and 8 of a 21-day cycle or capecitabine 1250 mg/m2 administered orally twice daily on days 1 to 14 of a 21-day cycle. All patients had locally advanced or metastatic breast cancer, < 3 prior chemotherapy regimens (< 2 for advanced disease), and prior treatment with anthracycline and taxane chemotherapy. Baseline characteristics were well balanced between the two treatment arms.
The results of the study showed that the median OS was 15.9 months for eribulin and 14.5 months for capecitabine (HR=0.879; 95% confidence interval [CI], 0.770-1.003; P=.056). Median PFS was 4.1 months and 4.2 months, respectively (HR=1.079; 95% CI, 0.932 — 1.250; P=.305). Overall response rates were 11% for eribulin and 12% for capecitabine (P=.849). OS for HER2-negative patients was 15.9 months for eribulin and 13.5 months for capecitabine (HR=0.838; 95% CI, 0.715 — 0.983; P=.030).
No new safety concerns emerged in the trial. Adverse events were consistent with the established safety profiles of both drugs. Adverse events occurring in more than 20% included neutropenia (54% for eribulin versus 16% for capecitabine), hand-foot syndrome (<1% versus 45%, respectively), alopecia (35% versus 4%, respectively), leukopenia (31% versus 10%, respectively), diarrhea (14% versus 29%, respectively), and nausea (22% versus 24%, respectively).
Kaufman PA, Awada A, Twelves C, et al. A phase III, open-label, randomized, multicenter study of eribulin mesylate versus capecitabine in patients with locally advanced or metastatic breast cancer previously treated with anthracyclines and taxanes. Presented at: 2012 CTRC-AACR San Antonio Breast Cancer Symposium; December 4-8, 2012; San Antonio, Texas. Abstract S6-6.