A phase Ib study of xentuzumab plus abemaciclib and fulvestrant in patients (pts) with advanced hormone receptor-positive (HR+), HER2-negative breast cancer (BC) with visceral or non-visceral disease.

1057Background: Cyclin-dependent kinase (CDK) 4 & 6 inhibitors plus endocrine therapy (ET) are standard of care for advanced HR+ BC. Combining xentuzumab, an insulin-like growth factor (IGF) ligand...