326PMONARCH 3: Updated time to chemotherapy and disease progression following abemaciclib plus aromatase inhibitor (AI) in HR+, HER2- advanced breast cancer (ABC)

Abstract Background In MONARCH 3, a randomized, double-blind, phase 3 trial; continuous dosing of abemaciclib in combination with an AI (anastrozole or letrozole) conferred significant clinical benefit to postmenopausal women with HR+, HER2- ABC. We here report data from an additional 12 months of follow-up in this trial including analysis for clinically prognostic subgroups (Di Leo et al., 2018). Methods From the 31 October 2018 data cutoff, exploratory intermediate efficacy parameters including time to subsequent chemotherapy ([TCT] time from randomization to first chemotherapy [CT]) and time to second disease progression ([PFS2] time from randomization to discontinuation date of first post-discontinuation treatment [PDT], or starting date of the secondPDT, or death) were assessed. TCT and PFS2 were analyzed using the Kaplan-Meier method in the intent to treat (ITT) and subgroups previously identified as significantly prognostic. Results In the ITT population, updated PFS was 28.2 vs 14.8 months (HR [95% CI]: 0.525 [0.415, 0.665]; p Conclusions Addition of abemaciclib to AI prolonged PFS2 and TCT in the ITT and all prognostic subgroups. Clinical trial identification NCT02246621. Editorial acknowledgement Medical writing support was provided by Anchal Sood and editorial assistance by Rod Everhart of Syneos Health, and funded by Eli Lilly and Company. Legal entity responsible for the study Eli Lilly and Company. Funding Eli Lilly and Company. Disclosure M. Martin: Research grant / Funding (institution), Travel / Accommodation / Expenses: Roche; Honoraria (self), Research grant / Funding (institution): Novartis; Honoraria (self): AstraZeneca; Honoraria (self): Pfizer; Honoraria (self): Eli Lilly and Company; Honoraria (self): Taiho Oncology; Honoraria (self): Pharmamar; Honoraria (self): Roche/Genentech. S. Johnston: Advisory / Consultancy, Research grant / Funding (self): AstraZeneca; Advisory / Consultancy: Eli Lilly and Company; Advisory / Consultancy, Speaker Bureau / Expert testimony: Novartis; Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self): Pfizer; Advisory / Consultancy, Research grant / Funding (self): Puma Biotechnology; Speaker Bureau / Expert testimony: Eisai. J. Huober: Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Eli Lilly and Company; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution), Travel / Accommodation / Expenses: Novartis; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Roche; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Pfizer; Honoraria (self), Advisory / Consultancy: Hexal; Honoraria (self), Advisory / Consultancy: AstraZeneca; Honoraria (self), Advisory / Consultancy: MSD; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution), Travel / Accommodation / Expenses: Celgene; Honoraria (self), Advisory / Consultancy: Abbvie. A. Di Leo: Honoraria (self), Advisory / Consultancy: Amgen; Honoraria (self), Advisory / Consultancy, Research grant / Funding (self), Travel / Accommodation / Expenses: AstraZeneca; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Bayer; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Celgene; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Eisai; Honoraria (self), Advisory / Consultancy: Genomic Health; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Eli Lilly and Company; Honoraria (self), Advisory / Consultancy, Research grant / Funding (self), Travel / Accommodation / Expenses: Novartis; Honoraria (self), Advisory / Consultancy, Research grant / Funding (self), Travel / Accommodation / Expenses: Pfizer; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Pierre Fabre; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Roche; Advisory / Consultancy, Travel / Accommodation / Expenses: Daiichi Sankyo; Advisory / Consultancy: Genentech; Advisory / Consultancy: Ipsen; Advisory / Consultancy, Travel / Accommodation / Expenses: Puma Biotechnology. V.A. Andre: Shareholder / Stockholder / Stock options, Full / Part-time employment: Eli Lilly and Company. H.R. Martin: Shareholder / Stockholder / Stock options, Full / Part-time employment: Eli Lilly and Company. M.C. Hardebeck: Shareholder / Stockholder / Stock options, Full / Part-time employment: Eli Lilly and Company. M.P. Goetz: Honoraria (self): Genomic Health; Advisory / Consultancy, Research grant / Funding (institution): Eli Lilly and Company; Advisory / Consultancy: Biovica; Advisory / Consultancy: Novartis; Advisory / Consultancy: Sermonix; Advisory / Consultancy: Context Pharm; Research grant / Funding (institution): Pfizer. All other authors have declared no conflicts of interest.