Vinorelbine After Prior Treatment With Eribulin for Advanced Breast Cancer: A Single-Centre Experience Suggesting Cross-Resistance.

ABSTRACT

INTRODUCTION: The tubulin inhibitor, eribulin, improves survival for previously treated advanced breast cancer (ABC) compared to chemotherapy of physician's choice, including vinorelbine, an older anti-tubulin. Vinorelbine is commonly still used after eribulin, but potentially risks cross-resistance and its efficacy in this setting is unproven. MATERIALS AND METHODS: A retrospective analysis of all patients who received vinorelbine after prior eribulin (VAE) 2011-2015 and a parallel cohort of consecutive patients who received vinorelbine without prior eribulin (VWE) for previously treated ABC between 2005 and 2011. Patient demographics, histopathological features, treatment duration and responses were recorded. The primary endpoint was progression-free survival from date of first vinorelbine for each cohort. Secondary endpoints included radiological response rate, and overall survival (OS). RESULTS: Thirty-five VAE and 103 VWE patients were identified, all female, 71.4% and 78.6% were ER positive/HER2 negative, 8.6% and 6.8% HER2 positive, and 20.0% and 14.6% triple negative for VAE and VWE cohorts, respectively. The median number of lines of chemotherapy lines prior to vinorelbine was 4 (range 2-6) and 2 (range 0-4), respectively. Fifteen VAE patients (42.9%) received ≥1 line of chemotherapy between eribulin and vinorelbine. VAE and WWE Patients received a median of 3 cycles of vinorelbine (range 1-9 and 1-12, respectively). The median progression-free survival for VAE patients was 2.1 months and 2.0 months for VWE patients. No VAE patients were progression-free at 24 weeks, compared to 15.5% of VWE patients. Median OS from commencing vinorelbine was 4.3 months for VAE and 6.4 months for VWE patients. CONCLUSION: Vinorelbine was of limited benefit after prior eribulin in our study, suggesting cross-resistance. Even without prior eribulin, only 15% of patients experienced clinical benefit from vinorelbine monotherapy.