406P - Safety and Efficacy of Vinorelbine Plus Low-Dose Metronomic Cyclophosphamide in Patients with Metastatic Breast Cancer Previously Treated with Anthracyclines and Taxanes

Abstract

ABSTRACT Aim: Metronomic chemotherapy has recently gained attention as a promising experimental strategy, involving alternative or complementary ways of using old and new anticancer chemotherapeutic agents. This study aimed to determine the toxicity, safety, and efficacy of a combination of vinorelbine and low-dose metronomic cyclophosphamide (CPA) in patients with metastatic breast cancer (MBC) previously treated with anthracyclines and taxanes. Methods: Eligibility criteria were as follows: human epidermal growth factor receptor (EGFR) 2 -negative MBC previously treated with anthracyclines and taxanes, ECOG PS 0 ∼ 1, and adequate bone marrow and organ function. Prior hormone therapy for MBC was permitted. In this study, patients received vinorelbine (40 mg/m2) intravenously on days 1 and 8, and CPA (100 mg) orally once daily on days 1 ∼ 14, every third week. The primary endpoints were the objective response rate (ORR) at 6 months and median time to progression (TTP). Secondary endpoints included safety and tolerability. Results: Between July 2010 and March 2014, 15 patients (median age 54.8 years [range, 37–67 years]) were enrolled. 80% were estrogen receptor and/or progesterone receptor positive, and 20% were triple negative. Sites of metastasis included the lymph nodes (53%), lungs (47 %), liver (47%), and bone (47%). Five patients (33%) had ≥3 sites of metastasis. A total of 179 cycles of chemotherapy were administered (median, 11 cycles; range, 1–29 cycles). The ORR at 6 months was 73.3%, including 6 (40%) patients with partial responses and 5 (33%) with stable disease. The median TTP was 9.2 months (95%CI). The most common hematologic toxicity was grade 2 neutropenia (30%); no grade 3/4 hematologic toxicity was observed. The most common non-hematologic toxicities were grade 1 hair loss (30%) and grade 2 neuropathy (20%). Discontinuation to adverse events did not occur. Conclusions: The combination of vinorelbine and low-dose cyclophosphamide is safe, with minimal adverse effects; it shows promising antitumor activity in patients with MBC refractory to anthracyclines and taxanes. Further clinical evaluation of this combination is warranted. Disclosure: All authors have declared no conflicts of interest.