Dovitinib plus fulvestrant in postmenopausal endocrine resistant HER2-/ HR+ breast cancer: A phase II, randomized, placebo-controlled study.

TPS651 Background: Overcoming endocrine resistance (ER) is a critical goal in the treatment of hormone receptor−positive (HR+) breast cancer (BC). Emerging in vitro evidence suggests that amplification and overexpression of fibroblast growth factor receptor 1 (FGFR1) is associated with ER. Up to 8% pts with HR+/ human epidermal growth factor receptor 2 negative (HER2–) BC have amplification of the FGFR1 gene. Dovitinib (DOV), a potent inhibitor of FGFR, vascular endothelial growth factor receptor, and platelet-derived growth factor receptor demonstrated antitumor activity in heavily pretreated BC pts with FGF-pathway amplification (FGFR1, FGFR2, or FGF3). The objective of this study is to determine if DOV plus fulvestrant (FUL) can improve outcomes in postmenopausal pts with endocrine resistant HER2-/HR+ BC. Methods: This multicenter, randomized, double-blind, placebo-controlled, ph II trial (NCT01528345) will enroll postmenopausal pts with HER2–/HR+ locally advanced or metastatic BC (N=150) progressing w...