Additional Relevant Details
The Phase 2 neoMONARCH trial was a randomized, multi-center, open-label study that enrolled 224 patients who had at least one measurable tumor ≥1 cm, adequate organ function, and an ECOG performance status of ≤1. Patients were randomized to one of three trial arms: 1) twice-daily abemaciclib monotherapy (150mg) for two weeks; 2) twice-daily abemaciclib (150mg) along with once-daily anastrozole (1mg) for two weeks; or 3) once-daily anastrozole monotherapy (1mg) for two weeks. All patients received an initial biopsy prior to randomization to assess baseline Ki67 expression. After the initial two-week treatment period, patients underwent a second tumor biopsy and Ki67 was assessed again.The primary objective of the study was to assess Ki67 percentage change in the breast tumor after two weeks of therapy from the baseline measurement. The results showed that abemaciclib monotherapy and abemaciclib in combination with anastrozole significantly reduced Ki67 more than anastrozole alone. Following the initial two weeks of randomized treatment, all patients then went on to receive twice-daily abemaciclib (150mg) plus anastrozole (1mg) for a further 14 to 22 weeks.The study protocol also included the prophylactic use of loperamide (2mg) administered twice-daily, in combination with abemaciclib for the first 28 days. No new safety signals were observed for abemaciclib when administered in combination with anastrozole.