Metronomic Chemotherapy for First-Line Treatment of Metastatic Triple-Negative Breast Cancer: A Phase II Trial

Background: Few data are available on the benefit of metronomic cyclophosphamide, capecitabine, and vinorelbine as first-line therapy in patients with metastatic triple-negative breast cancer. Methods: This phase II study assessed the safety and efficacy of metronomic oral chemotherapy with vinorelbine 40 mg orally 3 times a week, cyclophosphamide 50 mg daily, and capecitabine 500 mg 3 times a day (VEX regimen) in untreated metastatic triple-negative breast cancer patients. The biopsy of the metastatic site had to be triple-negative, independent of the hormone receptor expression of the primary tumor. The primary endpoint was time to progression (TTP). Secondary endpoints included assessment of safety and clinical benefit (objective response rate plus stable disease rate at ≥24 weeks). Results: 25 patients were included, and 22 were evaluable for both efficacy and toxicities (median age, 66 years). Median TTP was 6.4 months (95% confidence interval 3.6-12.6). The most common grade 1-2 toxicities were nausea, diarrhea, leuko-/neutropenia, and reversible liver enzyme alteration. Grade 3 events included hand and foot syndrome (9%). Conclusion: The VEX regimen demonstrated activity and was relatively well tolerated when given as first-line therapy in selected metastatic breast cancer patients with triple-negative disease