A phase 2 randomized, double-blind, placebo-controlled trial of radium-223 dichloride with exemestane and everolimus in patients with HER2–negative hormone receptor–positive breast cancer and bone metastases.

Abstract

TPS621Background: Treatment options for bone-dominant metastatic breast cancer (MBC) are limited.Radium-223 (Ra-223), a first-in-class α emitter with a targeted antitumor effect on bone metastases (mets), was well tolerated and reduced bone biomarker levels in a phase 2 study in patients with bone-dominant MBC (Coleman et al. Breast Cancer Res Treat 2014). In patients with HER2- estrogen receptor+ (ER+) bone-dominant MBC, everolimus + exemestane (EVE+EXE) improved progression-free survival (PFS) vs EXE alone. Ra-223 plus EVE+EXE may improve outcomes in patients with HER2- ER+ bone-dominant MBC; this trial will evaluate efficacy and safety of Ra-223 vs placebo in these patients (NCT02258451). Methods: Eligible patients are pre- or postmenopausal with HER2- ER+ MBC and ≥ 2 bone or soft tissue mets. Patients must have measurable disease per RECIST v1.1, ≥ 1 prior line of hormone therapy for MBC, and 1-2 prior skeletal-related events; be on bisphosphonates or denosumab; and have an ECOG score of 0-1. Patients...