Randomized Phase II Trial of Fulvestrant Plus Everolimus or Placebo in Postmenopausal Women With Hormone Receptor–Positive, Human Epidermal Growth Factor Receptor 2–Negative Metastatic Breast Cancer Resistant to Aromatase Inhibitor Therapy: Results of PrE0102

PurposeThe mammalian target of rapamycin inhibitor everolimus targets aberrant signaling through the PI3K/AKT/mammalian target of rapamycin pathway, a mechanism of resistance to anti-estrogen therapy in estrogen receptor (ER)–positive breast cancer. We hypothesized that everolimus plus the selective ER downregulator fulvestrant would be more efficacious than fulvestrant alone in ER-positive metastatic breast cancer resistant to aromatase inhibitor (AI) therapy.Patients and MethodsThis randomized, double-blind, placebo-controlled, phase II study included 131 postmenopausal women with ER-positive, human epidermal growth factor receptor 2–negative, AI-resistant metastatic breast cancer randomly assigned to fulvestrant (500 mg days 1 and 15 of cycle 1, then day 1 of cycles 2 and beyond) plus everolimus or placebo. The study was designed to have 90% power to detect a 70% improvement in median progression-free survival from 5.4 months to 9.2 months. Secondary end points included objective response and clinical ...