Successful Phase III trial, MONARCH 2,of abemaciclib and fulvestrant for hormone-receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), advanced breast cancer.- Eli Lilly

Eli Lilly and Company announced that its MONARCH 2 trial of abemaciclib met the primary endpoint of progression-free survival (PFS). The Phase III study evaluated abemaciclib, a cyclin-dependent kinase (CDK) 4 and CDK 6 inhibitor, in combination with fulvestrant in women with hormone-receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), advanced breast cancer who have relapsed or progressed after endocrine therapy. The results demonstrated the addition of abemaciclib to fulvestrant resulted in a statistically significant improvement in PFS, when compared to the control arm of placebo plus fulvestrant. Detailed efficacy and safety results will be presented at an upcoming medical meeting.

The global Phase III, double-blind study was designed to evaluate the efficacy and safety of abemaciclib, in combination with fulvestrant, in patients with advanced (locoregionally recurrent or metastatic) breast cancer. The intent-to-treat population of 669 patients was randomized to receive abemaciclib or placebo orally twice a day on a continuous dosing schedule, given in combination with fulvestrant at its approved dose and schedule, until disease progression. Patients enrolled in the study had experienced disease progression on or within 12 months of receiving endocrine treatment in the neoadjuvant or adjuvant setting or while receiving first-line endocrine therapy for metastatic disease. Patients who had received chemotherapy in the metastatic setting were not eligible for the study. The most common adverse events observed were diarrhea, neutropenia, nausea and fatigue, and were consistent with the previous studies of abemaciclib.

Comment:Along with MONARCH 1 and MONARCH 2, Lilly currently has additional trials evaluating abemaciclib in breast cancer. MONARCH 3 is a Phase III trial of abemaciclib in combination with a nonsteroidal aromatase inhibitor in patients with HR+, HER2- advanced breast cancer. Additionally, there is a Phase II MONARCH trial under way: monarcHER, which is evaluating abemaciclib plus trastuzumab (with or without fulvestrant) in women with HR+, HER2+ locally advanced or metastatic breast cancer. In each of these studies, abemaciclib is administered on a continuous dosing schedule.