Results from a phase III clinical trial comparing a newer chemotherapy agent called eribulin mesylate with capecitabine, a standard drug used for chemotherapy today in women with previously treated metastatic breast cancer, showed that eribulin demonstrated a trend toward improved overall survival. This study was presented today by Peter A. Kaufman, M.D., during the 2012 CTRC-AACR San Antonio Breast Cancer Symposium.
"We didn't show a statistically significant superiority of eribulin over capecitabine, which was our goal," said Peter A. Kaufman, MD, associate professor of medicine at the Geisel School of Medicine at Dartmouth, and oncologist at Dartmouth-Hitchcock and Norris Cotton Cancer Center in Lebanon, N.H. "However, 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. Additionally, this is the first study demonstrating that eribulin is active earlier in the course of metastatic breast cancer," Kaufman said.
In 2010, the FDA approved eribulin for the treatment of patients with metastatic breast cancer who had previously received an anthracycline and a taxane and at least two cytotoxic chemotherapy treatment regimens for metastatic breast cancer. The FDA granted approval based on data showing a statistically significant improvement in overall survival compared with current treatments.
Kaufman and colleagues examined whether eribulin would be effective as an earlier-line treatment in women with metastatic breast cancer. They randomly assigned 1,102 patients to eribulin or capecitabine. Patients had all received prior anthracycline- and taxane-based therapy and received the study drug as the first, second or third line of therapy for metastatic disease.
The median overall survival for patients treated with eribulin was 15.9 months compared with 14.5 months for patients treated with capecitabine.
"Although we did not meet our primary endpoints, this is still the first study demonstrating the activity of eribulin in earlier lines of treatment of metastatic breast cancer," Kaufman said. "Eribulin is an active therapy in this setting, and overall, it has potentially comparable activity to capecitabine, which is a widely used treatment in this patient population."
As a next step researchers are evaluating how eribulin performed among subsets of women in the study who share similar traits. Exploratory analyses of patient subsets showed that the median overall survival in women with HER2-negative breast cancer was 15.9 months with eribulin compared with 13.5 months with capecitabine. In women with triple-negative breast cancer, which is a particularly aggressive subset, the median overall survival was 14.4 months with eribulin compared with 9.4 months with capecitabine.
Kaufman and colleagues are still compiling data from the quality-of-life analysis, which according to Kaufman, will help guide their next steps in further studying eribulin in this patient population.