Background and objectives: There is an unmet need for new combination treatments, especially for aggressive, visceral, and high tumor burden metastatic breast cancer. Gemcitabine (GEM) has shown synergy with vinorelbine (VRL) in preclinical models, and has a toxicity profile that is different from VRL, another recently approved cytotoxic drug that seems to be effective in the treatment of breast cancer.
Methods: We studied the efficacy and side effects of the GEM-VRL combination as first-line chemotherapy in patients in an open-label, single arm, phase II study in patients with locally advanced or metastatic breast cancer who had been previously treated with an anthracycline-based regimen in the adjuvant/neoadjuvant setting.
Results: Of the 74 patients enrolled, 72 patients were evaluable for the primary treatment outcome (tumor response rates). Four patients (6%) had a complete response and 26 patients (36%) had a partial response. Nineteen patients (26%) had stable disease. The median time to disease progression was 37 weeks (range, 1-60 weeks). Median duration of response was 43 weeks (range, 8.6 to 55 weeks) and one-year survival was 77% (95% confidence interval, 64% to 86%). Grade 3-4 neutropenia without fever was reported in 10% of patients, thrombocytopenia in 1%, and febrile neutropenia in 11%. The most common clinical grade 3-4 toxicities were nausea (24%) and diarrhea and stomatitis (11% each). Hospitalizations for adverse events mainly due to anemia, febrile neutropenia, septic shock and hepatic failure occurred in 7%.
Conclusion: With an overall response rate of 42%, the GEM-VRL combination had promising efficacy and good tolerability in metastatic breast cancer patients.