Hurvitz SA, et al. - Among premenopausal patients (pts) with hormone receptor–positive (HR+)/HER2− ABC, the therapeutic impacts of endocrine therapy (ET) ± a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor were assessed in phase III MONALEESA-7 study, for the first time ever. Ribociclib (RIB) or placebo + goserelin and either a nonsteroidal aromatase inhibitor (NSAI; letrozole or anastrozole) or tamoxifen was administered to premenopausal pts (N=672) with HR+/HER2− ABC. This represents the 2nd of 3 protocol-specified OS analyses (scheduled to occur following approximately 189 deaths [75% of the planned total events]). In premenopausal pts with HR+/HER2− ABC, a clinically and statistically significant longer OS was achieved with RIB + ET vs ET alone. As initial endocrine-based therapy, a CDK4/6 inhibitor or any targeted agent + ET has shown significantly longer OS, compared to ET alone, for the first time in this study.