In all, 1,102 patients were randomized to eribulin – the only chemotherapeutic agent shown to have a survival benefit in heavily pretreated metastatic breast cancer – or capecitabine. The former is approved by the FDA for treatment of metastatic breast cancer after at least two treatment regimens with an anthracycline and a taxane; the latter is approved for treatment of pretreated metastatic breast cancer, as well as stage III colon cancer.
Demographically, the patients had a median age of 53 years. The majority had received one or two prior chemotherapy regimens for advanced disease. More than 85% had visceral involvement.
In terms of drug exposure, the two groups had almost identical median durations of treatment and relative dose intensities.
Main results showed that median overall survival achieved with eribulin was numerically but not statistically better than that with capecitabine (15.9 vs. 14.5 months; hazard ratio, 0.88; P = .056), Dr. Kaufman reported.
In preplanned subgroup analyses, there were trends favoring eribulin over capecitabine in patients who had triple-negative disease (hazard ratio, 0.70), as well as those with HER2-negative disease (0.84) and estrogen receptor–negative disease (0.78).
The 1-, 2-, and 3-year rates of overall survival were statistically indistinguishable between groups.
There was also no significant difference in progression-free survival, with the value standing at about 4 months in each group (P = .31), and no significant difference in response rates.
The eribulin and capecitabine groups were similarly likely to experience treatment-related adverse events (85% and 77%) and serious adverse events (18% and 21%).
"The side effect profiles are consistent with previous data on the side effects of these medications," Dr. Kaufman said.
Eribulin was associated with higher rates of grade 3/4 neutropenia and leukopenia, whereas capecitabine was associated with higher rates of grade 3/4 hand-foot syndrome and diarrhea.
The investigators have not yet performed comparative cost analyses in the trial.
Dr. Kaufman disclosed that he receives research support from and is a consultant to Eisai. The trial was sponsored by Eisai.