Toxicity Of Prolonged Treatment With Eribulin (E) In Metastatic Breast Cancer (Mbc) Patients: Results Of The Exter Study.

e11528 Background: Treatment with eribulin, the first halichondrin derivative for human use, is an emergent option for the second and third-line treatment of MBC. The EXTER study has included MBC patients with long-lasting ( u003e 7 months) response to eribulin. Since median duration of treatment for pivotal studies of E is around 3 months, availability of toxicity data for longer treatments is limited. We studied the adverse events profile of patients included in the EXTER study, in order to evaluate whether any cumulative toxicity may limit prolonged treatment. Methods: We analyzed the toxicity of MBC patients receiving E for at least 7 months and included in an observational, retrospective study in 30 hospitals. Toxicity was categorized according to CTCAE 4.0 criteria and classified into two categories: adverse events (any grade from 1 to 4) (AE) and severe adverse event (corresponding to grade 3-4 extra-hematologic toxicity or grade 4 hematologic toxicity). Results: Median duration of treatment was 8.5 mo...