Multi-institutional prospective observational study of the effectiveness of eribulin in first-line or second-line chemotherapy for HER2-negative hormone-resistant advanced or metastatic breast cancer: The KBCRN A001: E-SPEC Study

Abstract PurposeTo investigate the survival impact of eribulin use in first-line and second-line chemotherapy for patients with endocrine-resistant advanced or metastatic breast cancer (AMBC) in the real-world clinical setting. MethodsThis multi-institutional prospective cohort study enrolled patients with triple-negative AMBC or estrogen receptor (ER)-positive AMBC refractory to at least one previous endocrine therapy selected at the physician’s discretion. The overall survival from the start of first-line (OS1) and second-line chemotherapy (OS2) were assessed. Adjusted hazard ratio (HR) between eribulin and the other regimens (oral 5-fluorouracil [5-FU] and anthracycline/taxane) was calculated using a stratified proportional hazards model that included prespecified prognostic factors. ResultsOf the 201 patients enrolled, 180 were included in the final analysis. Baseline patient characteristics were quite diverse among regimens. The median OS1 was 2.25, 3.49, and 2.62 years for eribulin (n=46), oral 5-FU (n=57), and anthracycline/taxane (n=71), and the median OS2 was 1.75, 2.33, and 1.69 years for eribulin (n=70), oral 5-FU (n=26), and anthracycline/taxane (n=44), respectively. First-line eribulin had a worse adjusted HR for OS than the other regimens in the ER-negative cohort; second-line oral 5-FU had a better adjusted HR for OS than eribulin in the ER-positive cohort. There was no significant difference between regimens in the other subgroups.ConclusionsEribulin and anthracycline/taxane resulted in similar point estimates for OS, while oral 5-FU led to relatively longer survival. Adjusted HRs differed based on treatment line and ER status. However, caution should be exercised when interpreting the results due to the heterogamies in patient background.Trial registration number and date of registrationClinical Trials.gov (NCT 02551263), July 22, 2015.