Single arm, multicentre, non-randomized open-label trial to evaluate the safety of eribulin in third line chemotherapy in patients with HER2-negative metastatic or locally advanced breast cancer previously treated with anthracyclines and taxanes: Onsite study (ONCOSUR 2012-02)

Eribulin monotherapy is indicated for the treatment of patients with locally advanced or metastatic breast cancer who have progressed after at least one chemotherapy regimen for advanced disease. In an updated analysis of the EMBRACE study, survival improved in patients with 2-3 previous regimens (13.3 months vs 10.7 months HR 0.77, P = .039). Patients received eribulin (1.23 mg/m2 on days 1 and 8 of every 21-day cycle) as third-line therapy until progression, unacceptable toxicity or withdrawal. The primary endpoint was safety, and secondary endpoints included objective response rate, clinical benefit, 1-year overall survival and progression free survival (PFS) rates, and circulating tumour cell levels (EudraCT number 2013-001416-30). Out of 59 eligible women (mean age 57.7), 58 (98.3%) had received previous taxanes and/or anthracyclines. Nearly all (98.3%) had HER2-negative tumors, 72% were positive for estrogens, 21% were triple negative; 64.4% had liver metastasis and 57.6% bone metastasis. Grade 3 or 4 hematologic adverse events were febrile neutropenia (N = 3; 5%) and neutropenia (n = 2; 3%). The most common non-hematologic adverse events were grade 1-2 asthenia (n = 2; 3%), grade 1-2 constipation (n = 2; 3%) and grade 1-2 skin rash (n = 1; 1%). Mean number of administered cycles was 6.9 ± 5.4. Follow-up was performed in 52 patients, with 19.2% (n = 10) partial response, 42.3% (n = 22) stable disease, and 38% (n = 20) progressive disease. Clinical benefit was achieved in 32 patients (61.5%). Median PFS was 5.13 months (95% CI 3.23, 8.90). After one year, 47 patients were still alive (81.03%). Treatment with eribulin in third line chemotherapy for locally advanced or metastatic breast cancer is effective and minimally toxic, presenting a high clinical benefit rate.