Quick Take: Overall survival with ribociclib plus endocrine therapy in breast cancer

Hormone therapy is the standard of care for premenopausal and postmenopausal women with hormone receptor-positive, human epidermal growth factor receptor2 (HER2)-negative advanced breast cancer. Ribociclib is an orally administered CDK4/6 inhibitor. Multiple trials have shown that combined ribociclib and endocrine therapy result in significantly improved progression-free survival compared to endocrine therapy alone in this setting; however,no previous trials have shown a definitive improvement in overall survival. In this second interim analysis from Mammary Oncology Assessment of LEE011’s [Ribociclib’s] Efficacy and Safety-7 (MONALEESA-7), an international, randomized, double-blind placebo-controlled phase III trial, researchers compared ribociclib versus placebo in addition to endocrine therapy with goserelin and either a nonsteroidal aromatase inhibitor or tamoxifen, in women age 18 to 59 years with histologically or cytologically confirmed hormone receptor-positive, HER2-negative advanced breast cancer. Overall survival was the main outcome for this secondary analysis. Of 672 patients included in the intention-to-treat population, 83 (24.8%) and 109 (32.3%) deaths occurred in the ribociclib and placebo groups, respectively. The addition of ribociclib resulted in significantly longer overall survival (70.2% vs. 46.0% alive at 42 months; HR 0.71, 95% CI 0.54 to 0.95, p=0.00973). This benefit was also seen in the subgroup of patients receiving aromatase inhibitors as hormonal therapy. This secondary analysis from the MONALEESA-7 trial therefore shows significantly longer overall survival associated with the addition of a CDK4/6 inhibitor to baseline endocrine therapy for patients with advanced hormone receptor-positive, HER2-negative breast cancer.

Click to read the study in NEJM

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