A randomized phase II study comparing capecitabine (C) with C plus oral cyclophosphamide (CCy) in patients (pts) with advanced breast cancer (BC)

1077 Background: C is an active cytotoxic, either alone or in combination, for patients with advanced BC. Cyclophosphamide has nonoverlapping toxicities with C, and shows synergistic activity preclinically. We explored the feasibility, efficacy, and toxicity of an all-oral combination of CCy vs C alone in a multicenter, national, randomized, Phase II study. Methods: Patients with locally advanced or metastatic BC eligible for 1st- or 2nd-line chemotherapy were randomized to treatment with either C alone 666 mg/m2 bid continuously days 1–28, or C plus oral cyclophosphamide 100 mg/m2 days 1–14 on a 28-day cycle for up to 6 cycles. Co-primary endpoints were tumor response and toxicity profile. Secondary endpoints were progression-free survival (PFS) and overall survival (OS). In the 3-region design differences in tumor response were set a priori such that i) >20% would be considered evidence of benefit of CCy over C; ii) between 7.6% and 20% would indicate that CCy should be evaluated further; and iii) <7.6%...