Eribulin Improves Survival of Women with Metastatic Breast Cancer

Treatment with eribulin (Halaven™) improved overall survival in women with metastatic breast cancer whose disease progressed despite multiple rounds of prior chemotherapy, according to the results of a phase III clinical trial called EMBRACE. Based on these findings, the FDA approved eribulin last November for women with metastatic disease who have already undergone at least two previous chemotherapy regimens.

The study results were published online March 2, 2011, in The Lancet.

The improvement in overall survival makes the findings “clinically meaningful,” wrote the study’s lead author, Javier Cortes, M.D., of the Vall d'Hebron Institute of Oncology in Barcelona, Spain, and his colleagues. “To our knowledge, EMBRACE is the first major single-agent study of a cytotoxic or biological agent to show significantly increased survival in patients with such heavily pretreated metastatic breast cancer.”

Eribulin is a laboratory-made form of halichondrin B, a substance derived from a sea sponge. Similar to some other chemotherapy drugs, it targets the protein tubulin in cells, although it binds to tubulin in a different way, interfering with cancer cell division and growth.

In the trial—funded by Eisai Co., Ltd., which manufactures eribulin—762 patients were randomly assigned to receive either eribulin or the treating physicians’ choice of therapy. Prior to enrolling, trial participants had received, on average, four previous chemotherapy regimens. Because there is no standard of care for women with progressive metastatic breast cancer, the treatments eribulin was compared with “[reflect] real-life choices made by oncologists and their patients,” the researchers wrote.

Women who received eribulin, on average, lived 2.5 months longer than those treated with their physician’s choice (13.1 months versus 10.6 months). Progression-free survival was similar between the groups. Overall, serious side effects were roughly equal in women in both trial arms, although women treated with eribulin had more serious cases of neutropenia, leukopenia, and peripheral neuropathy.

“EMBRACE provides much needed, high-level evidence for chemotherapy use in patients with heavily pretreated breast cancer,” wrote Nancy Lin, M.D., and Harold Burstein, M.D., Ph.D., of Dana-Farber Cancer Institute, in an accompanying editorial. But a number of important questions remain about the use of eribulin in this group of patients, they noted, including whether there is a subgroup that is more likely to respond to the drug.

“The clinical gains from EMBRACE are sufficiently narrow,” the study authors continued, “that a better understanding of the relation between treatment, symptom control, and quality of life in study participants remains crucial.”