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°®¶¹´«Ã½. (Headquarters: Tokyo, President & CEO: Haruo Naito, “Eisai”) announced today that the results of a Phase III study (Study 301) of Halaven® (eribulin mesylate) versus capecitabine in locally advanced or metastatic breast cancer were presented at the 2012 CTRC-AACR San Antonio Breast Cancer Symposium (SABCS) in the United States. The head-to-head study compared anticancer agents Halaven and capecitabine in patients with locally advanced or metastatic breast cancer who had received prior treatment that included an anthracycline and a taxane.

The multicenter, randomized, open-label study compared Halaven versus capecitabine in 1,102 patients with locally advanced or metastatic breast cancer in which prior treatment with anthracyclines and taxanes had been unsuccessful, with the majority of these patients receiving study treatment as their 1^st- or 2^nd-line chemotherapeutic regimen for metastatic disease. The co-primary endpoints of the study were overall survival (OS) and progression-free survival (PFS).

Results from the study demonstrated a trend that favored improved OS with Halaven compared with capecitabine, although the improvement was not statistically significant. Patients treated with Halaven had a median OS of 15.9 months versus 14.5 months with capecitabine (HR 0.879; 95% CI: 0.770-1.003; p=0.056). No difference was observed in the median PFS of the two groups in an independent review, with 4.1 and 4.2 months for Halaven and capecitabine respectively (HR 1.079; 95% CI: 0.932-1.250; p=0.305).

The study carried out a series of exploratory analyses, including one analysis based on the expression status of human epidermal growth factor receptors (HER2s), which was a pre-specified stratification factor in the study protocol, and other analyses based on hormone receptor expression status, which were not pre-specified stratification factors in the study. These analyses showed that in a subset of HER2-negative patients (n=755), the median OS was 15.9 months for Halaven and 13.5 months for capecitabine (HR 0.838; 95% CI: 0.715-0.983; nominal p=0.030). Furthermore, in triple negative breast cancer patients (n=284), a group with extremely high unmet medical needs in which the disease is HER2-negative, estrogen receptor-negative and progesterone receptor-negative, the median OS was 14.4 months for Halaven and 9.4 months for capecitabine (HR 0.702; 95% CI: 0.545-0.906; nominal p=0.006).

In regard to safety, adverse events (AEs) were consistent with the known side-effect profiles of both drugs. The most common AEs (events with an incidence rate of at least 20%) for Halaven and capecitabine were, respectively, neutropenia (54.2% vs. 15.9%), hand-foot syndrome (0.2% vs. 45.1%), alopecia (34.6% vs. 4.0%), leukopenia (31.4% vs. 10.4%), diarrhea (14.3 vs. 28.8%), and nausea (22.2% vs. 24.4%).

The trial studied Halaven versus capecitabine, which is currently approved in Europe and the United States as an earlier-stage breast cancer therapy than Halaven. While Halaven did not statistically meet either co-primary endpoint, the data do demonstrate a trend that favored improved OS with Halaven compared with capecitabine as well as a clinically meaningful improvement in OS for Halaven in certain patient groups, such as patients with HER2-negative or triple-negative disease and further work should be undertaken.

Although advances are being made in the treatment of breast cancer each year in line with the development of new anticancer agents, the unmet medical needs of locally advanced or metastatic breast cancer patients continue to remain high. Halaven is currently approved for the treatment of breast cancer in 42 countries worldwide, including Japan, the United States, European Union (EU) member states and Singapore. Eisai remains committed to generating scientific evidence aimed at maximizing the value of Halaven as it seeks to make further contributions to address the diversified needs of, and increase the benefits provided to, cancer patients and their families as well as healthcare providers.