Eribulin mesylate (ERI) exerts anticancer activity in both early- and late-line settings in the management of ER+HER2- metastatic breast cancer (MBC) patients; however, the utility of rechallenge or a second administration of ERI has not been well discussed.
The outcomes of ER+HER2-MBC patients who received ERI therapy at our institute from November 2011 to the present were reviewed. Statistical analyses were performed using the Kaplan-Meyer method and Spearman's rank correlation coefficient.
We identified 90 ER+HER2-MBC patients who had terminated their first-line of ERI therapy (1stERI), with a median time-to-treatment failure (TTF) of 134.0 days (95% confidence interval [CI]115.6-152.4), and 22 of 90 (24.4%) underwent a 2ndERI. Of these 22 patients, the TTF was significantly better than at the 1stERI compared with patients who did not undergo 2ndERI (median 181.0 days vs. 119.0 days; P < 0.01). Patients received a median of 2 (range 1-5) regimens between the 1st- and 2nd- ERI, and the median number of regimens patients received prior to 2ndERI was 4 (range 2-10). A majority (16/22, 72.7%) received chemotherapy prior to the 2ndERI. The median TTF of prior systemic therapy was 141.0 days (95% CI 70.9-211.1), and the major cause of discontinuation was progression of known lesions (19/22, 86.4%). The median TTF of the 2ndERI was 97.0 days (95% CI 82.2-111.8), and causes of discontinuation (excluding 1 patient still on treatment) were as follows: progression of known lesions, 14 (66.7%); development of new lesions, 2 (9.5%) and others, 5 (23.8%). Among them, 3 pts achieved stable disease for ≥24 weeks. Subsequent systemic therapy was introduced to 16/21 (76.2%) patients, and 11 received chemotherapy. The median overall survival (OS) from the induction of the 2ndERI was 268.0 days (95% CI 16.1-519.9), and the median OS from the induction of the 1stERI was significantly improved by the 2ndERI (898.0 days vs. 421.0 days; P < 0.001). A significant (P < 0.001) relationship existed between the TTF of the 2ndERI and the OS from the induction of the2ndERI. No significant safety signals were noted.
Re-challenging eribulin is thus considered to be a viable option for patients with ER+HER2-MBC in terms of the efficacy and safety.
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