Efficacy and Safety of Ribociclib With Letrozole in US Patients Enrolled in the MONALEESA-2 Study

Denise A. Yardley, Lowell Hart, Anne Favret, S. Blau, Sami Diab, Donald Richards, Joseph Sparano, J. Thad Beck, Paul Richards, Patrick Ward, Bhuvaneswari Ramaswamy, Michaela Tsai, Kimberly Blackwell, Timothy Pluard, Sara M. Tolaney, Francisco J. Esteva, Cristina I. Truica, Carlos Alemany, Gena Volas-Redd, Mikhail ShtivelbandDas Purkayastha, Anand A. Dalal, Michelle Miller, Gabriel N. Hortobagyi

Research output: Contribution to journalArticle

Abstract

Background: In the Mammary Oncology Assessment of LEE011’s (Ribociclib's) Efficacy and Safety (MONALEESA-2) study, combination treatment with the selective inhibitor of cyclin-dependent kinases 4/6 ribociclib with letrozole significantly improved progression-free survival (PFS) versus letrozole alone in postmenopausal women with hormone receptor-positive HR+/HER2 advanced breast cancer (ABC). Herein we present results from the subset of US patients enrolled in MONALEESA-2. Patients and Methods: Postmenopausal women with HR+/HER2 ABC without previous treatment for advanced disease were randomized (1:1) to ribociclib 600 mg/d (3 weeks on/1 week off) with letrozole 2.5 mg/d (continuous) or placebo with letrozole. The primary end point was locally assessed PFS. Results: Overall, 213 US patients were enrolled in MONALEESA-2 (ribociclib, n = 100; placebo, n = 113). Baseline characteristics were similar between treatment groups and consistent with the global population. With a median follow-up of 27 months, 38 (38%) and 29 (26%) patients in the ribociclib and placebo groups, respectively, had continued to receive treatment. Median PFS was 27.6 months with ribociclib and 15.0 months with placebo (hazard ratio, 0.53). The most common all-cause adverse events were neutropenia (ribociclib, 72.0% [n = 72]; placebo, 4.6% [n = 5]), nausea (ribociclib, 69.0% [n = 69]; placebo, 44.0% [n = 48]), and fatigue (ribociclib, 60.0% [n = 60]; placebo, 50.5% [n = 55]). Two patients (ribociclib, 2.0%; placebo, 0%) experienced febrile neutropenia. Conclusion: In the US subset of MONALEESA-2, ribociclib with letrozole showed superior efficacy versus letrozole alone. These findings are consistent with the global population and support first-line use of ribociclib with letrozole in patients with HR+/HER2 ABC. Endocrine therapy is standard care for postmenopausal women with hormone receptor-positive (HR+)/HER2 advanced breast cancer (ABC). A Mammary Oncology Assessment of LEE011’s (Ribociclib's) Efficacy and Safety (MONALEESA-2) study subset of postmenopausal women with HR+/HER2 ABC without previous treatment for advanced disease were randomized to ribociclib/letrozole or placebo/letrozole. Improved progression-free survival was observed in patients treated with first-line ribociclib/letrozole versus placebo/letrozole, consistent with the global population. These results suggest ribociclib/letrozole is safe and effective in this patient population.

Original languageEnglish (US)
Pages (from-to)268-277.e1
JournalClinical Breast Cancer
Volume19
Issue number4
DOIs
StatePublished - Aug 2019

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

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    Yardley, D. A., Hart, L., Favret, A., Blau, S., Diab, S., Richards, D., Sparano, J., Beck, J. T., Richards, P., Ward, P., Ramaswamy, B., Tsai, M., Blackwell, K., Pluard, T., Tolaney, S. M., Esteva, F. J., Truica, C. I., Alemany, C., Volas-Redd, G., ... Hortobagyi, G. N. (2019). Efficacy and Safety of Ribociclib With Letrozole in US Patients Enrolled in the MONALEESA-2 Study. Clinical Breast Cancer, 19(4), 268-277.e1. https://doi.org/10.1016/j.clbc.2019.02.007