Background: PN is a known adverse effect of various antimicrotubule agents, including eribulin. We report here the incidence and resolution of PN in breast cancer pts treated with eribulin in completed phase 2 and 3 studies, and the efficacy of eribulin in pts with PN in the phase 3 EMBRACE and 301 studies. Methods: In EMBRACE, women had received 2-5 lines of chemotherapy for advanced disease. In this ≥ 3rd-line setting, pts randomized to eribulin mesylate received it at 1.4 mg/m² iv, days 1 and 8 every 21 days. The dosing schedule was the same in study 301, which involved pts who had received 0-2 prior chemotherapies for advanced disease. Overall survival (OS) and progression-free survival (PFS) were analyzed by stratified log-rank test. Data from EMBRACE and 301 were pooled with data from 2 phase 2 studies to assess time to improvement (a decrease of ≥ 1 grade) and resolution (decrease in grade to 0, 1 or baseline) of grade 3 or 4 PN. Results: In the pooled safety analysis, 7.7% (116/1503) of pts treated with eribulin had grade 3 or 4 PN; 63.8% of these experienced improvement in PN and 50% had resolution. Median time to improvement was 2.1 weeks and to resolution was 7.7 weeks. Characteristics were similar in pts with or without PN in EMBRACE and 301. Those with PN had longer exposure to eribulin vs pts without PN (median exposure [months], study 301: 4.9 vs 3.2; EMBRACE: 4.8 vs 2.9). OS and PFS were significantly longer in pts with PN (Table). Conclusions: Pts who had a favourable therapeutic response to eribulin, received a longer course of treatment and thus had a greater risk of PN. Severity of PN improved in most pts within a short period. Regarding PN, the risk–benefit ratio for eribulin supports treatment. Clinical trial information: NCT00337103, NCT00388726.

*Based on independent review committee assessment. Hazard ratio for PN vs no PN.