A drug approved for use in patients with metastatic breast cancer who had undergone several previous treatments may help improve survival when administered earlier in the disease course.

Data presented at the CTRC-AACR San Antonio Breast Cancer Symposium, held December 4-8, 2012, in San Antonio, Texas, described a study in which eribulin mesylate was compared with capecitabine, an antimetabolite that is a standard chemotherapy agent in the treatment of metastatic breast cancer. Eribulin mesylate, which belongs to a class of anticancer medications known as microtubule dynamics inhibitors, won FDA approval in 2010 for the treatment of patients with metastatic breast cancer who had previously undergone treatment with an anthracycline and a taxane as well as at least two cytotoxic chemotherapy regimens. The approval of eribulin was based on data showing a statistically significant improvement in overall survival compared with current treatments, recounted a statement describing the current study from Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire.

Peter A. Kaufman, MD, an oncologist at Dartmouth-Hitchcock Medical Center and the Dartmouth-Hitchcock Norris Cotton Cancer Center, also in Lebanon, New Hampshire, and colleagues randomly assigned 1,102 women with metastatic breast cancer to receive treatment with eribulin or capecitabine. The participants, who had all undergone prior anthracycline- and taxane-based therapy, received the study drug as the first, second, or third line of therapy.

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Median overall survival in the eribulin group was 15.9 months, compared with 14.5 months for the capecitabine users. Exploratory analyses of patient subsets showed that among women with HER2-negative breast cancer, median survival was 15.9 months with eribulin and 13.5 months with capecitabine. In the subset of women with triple-negative breast cancer, a particularly aggressive form of the disease, median overall survival was 14.4 months with eribulin, compared with 9.4 months with capecitabine.

Data from quality-of-life analyses are still being compiled.

Although the researchers did not meet their goal of showing statistically significant superiority of eribulin over capecitabine, “Eribulin demonstrated a trend favoring an overall survival benefit in comparison to capecitabine, which is a widely accepted and used standard therapy in this setting,” noted Kaufman in a statement issued by Dartmouth-Hitchcock Medical Center. “Additionally, this is the first study demonstrating that eribulin is active earlier in the course of metastatic breast cancer.”