Phase 2 study of cabazitaxel as second-line treatment in patients with HER2-negative metastatic breast cancer previously treated with taxanes—a Hellenic Cooperative Oncology Group (HeCOG) Trial

BACKGROUND: Cabazitaxel is a novel taxane that might be active in breast cancer resistant to first-generation taxanes. METHODS: The purpose of the current multicentre phase II trial was to evaluate the activity and safety of cabazitaxel, as second-line treatment, in patients with human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC) previously treated with taxanes. The primary endpoint was objective response rate (ORR). RESULTS: Eighty-four patients were enrolled between October 2012 and November 2016. Taxane resistance to previous treatment was detected in 43 cases. The ORR was 22.6% in the intent-to-treat population, 23.3% in taxane-resistant and 20.5% in taxane-non-resistant cases. At a median follow-up of 39.6 months, the median progression-free survival and overall survival were 3.7 months (95% CI 2.2–4.4) and 15.2 months (95% CI 11.3–19.4), respectively. Regarding toxicity, grade 3–4 neutropenia was reported in 22.6% and febrile neutropenia in 6% of the patients, respectively. Two fatal events (one febrile neutropenia and one sepsis) were reported as being related to study treatment. CONCLUSIONS: This phase II trial suggests that cabazitaxel is active as second-line treatment in taxane-pretreated patients with HER2-negative MBC, with manageable toxicity.