Overall Survival with Ribociclib plus Letrozole in Advanced Breast Cancer

Gabriel N. Hortobagyi, Salomon M. Stemmer, Howard A. Burris, Yoon Sim Yap, Gabe S. Sonke, Lowell Hart, Mario Campone, Katarina Petrakova, Eric P. Winer, Wolfgang Janni, Pierfranco Conte, David A. Cameron, Fabrice André, Carlos L. Arteaga, Juan P. Zarate, Arunava Chakravartty, Tetiana Taran, Fabienne Le Gac, Paolo Serra, Joyce O’Shaughnessy

Research output: Contribution to journalArticlepeer-review

115 Scopus citations


BACKGROUND In a previous analysis of this phase 3 trial, first-line ribociclib plus letrozole resulted in significantly longer progression-free survival than letrozole alone among postmenopausal patients with hormone receptor (HR)–positive, human epidermal growth factor receptor 2 (HER2)–negative advanced breast cancer. Whether overall survival would also be longer with ribociclib was not known. METHODS Here we report the results of the protocol-specified final analysis of overall survival, a key secondary end point. Patients were randomly assigned in a 1:1 ratio to receive either ribociclib or placebo in combination with letrozole. Overall survival was assessed with the use of a stratified log-rank test and summarized with the use of Kaplan–Meier methods after 400 deaths had occurred. A hierarchical testing strategy was used for the analysis of progression-free survival and overall survival to ensure the validity of the findings. RESULTS After a median follow-up of 6.6 years, 181 deaths had occurred among 334 patients (54.2%) in the ribociclib group and 219 among 334 (65.6%) in the placebo group. Ribociclib plus letrozole showed a significant overall survival benefit as compared with placebo plus letrozole. Median overall survival was 63.9 months (95% confidence interval [CI], 52.4 to 71.0) with ribociclib plus letrozole and 51.4 months (95% CI, 47.2 to 59.7) with placebo plus letrozole (hazard ratio for death, 0.76; 95% CI, 0.63 to 0.93; two-sided P=0.008). No new safety signals were observed. CONCLUSIONS First-line therapy with ribociclib plus letrozole showed a significant overall survival benefit as compared with placebo plus letrozole in patients with HR-positive, HER2-negative advanced breast cancer. Median overall survival was more than 12 months longer with ribociclib than with placebo. (Funded by Novartis; MONALEESA-2 ClinicalTrials.gov number, NCT01958021.)

Original languageEnglish (US)
Pages (from-to)942-950
Number of pages9
JournalNew England Journal of Medicine
Issue number10
StatePublished - Mar 10 2022
Externally publishedYes

ASJC Scopus subject areas

  • Medicine(all)


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