Breast Cancer Coverage from Every Angle

ASCO 2019: CDK4/6 Inhibitor Plus Endocrine Therapy Improves Overall Survival in Advanced Breast Cancer

By: Kayci Reyer
Posted: Monday, June 3, 2019

According to recent findings from the phase III MONALEESA-7 trial, presented at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract LBA1008), adding the CDK4/6 inhibitor ribociclib to endocrine therapy significantly improved overall survival in premenopausal women with hormone receptor–positive/HER2-negative advanced breast cancer when compared with endocrine therapy alone (70.2% vs. 46.0%).

“This is the first time that a CDK4/6 inhibitor or any targeted agent plus [endocrine therapy] has demonstrated significantly longer [overall survival] versus [endocrine therapy] alone as initial endocrine-based therapy,” concluded Sara A. Hurvitz, MD, Director of the Breast Cancer Clinical Research Program at the University of California, Los Angeles Jonsson Comprehensive Cancer Center, and colleagues.

The study included 672 premenopausal patients with hormone receptor–positive/HER2-negative advanced breast cancer who were treated with goserelin plus either ribociclib or a placebo. Participants also received either a nonsteroidal aromatase inhibitor (n = 495) or tamoxifen. The median follow-up was 34.6 months following the data-gathering cutoff of November 30, 2018, at which point 173 patients were still receiving treatment (ribociclib, n = 116; placebo, n = 57).

The median overall survival was calculated after 192 deaths occurred (ribociclib, n = 83; placebo, n = 109) and was significantly longer with ribociclib than with placebo (not reached versus 40.9 months; hazard ratio = 0.712; P = .00973). Similarly, estimated overall survival rates at 42 months were also longer with ribociclib than with placebo (70.2% vs. 46.0%). Among patients receiving a nonsteroidal aromatase inhibitor, endocrine therapy plus ribociclib continued to demonstrate improved overall survival versus endocrine therapy plus placebo (hazard ratio = 0.699). Both treatment groups received post-treatment therapy (ribociclib, 68.9%; placebo, 73.2%).

Disclosure: This study received funding from Novartis. The study authors’ disclosure information may be found at

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