MONARCH 3 study positive for abemaciclib in combination with a nonsteroidal aromatase inhibitor as treatment of postmenopausal women with advanced breast cancer.- Eli Lilly.

MONARCH 3 is a global Phase III, double-blind, placebo-controlled study, which evaluated the efficacy and safety of abemaciclib in combination with a nonsteroidal aromatase inhibitor (letrozole or anastrozole) as initial endocrine-based therapy for postmenopausal women with advanced breast cancer who have had no prior systemic treatment for advanced disease. Eli Lilly presented out more positive data for candidate abemaciclib .

Compared to placebo in the phase III study announced at the European Society for Medical Oncology (ESMO) annual meeting in Madrid, abemaciclib cut the risk of disease progression or death by 46%. Overall response rate measured 59.2% for the abemaciclib arm—compared with 44% in the placebo arm. A problem could be the side effects: 81.3% of Monarch 3’s abemaciclib cohort experienced diarrhea, compared with just 29.8% of placebo patients. In Monarch 2, the abemaciclib diarrhea rate reached 86.4%. However, only 9.5% of Monarch 3’s diarrhea sufferers experienced grade 3 diarrhea, and the malady was “highly predictable and readily manageable” with OTC remedy-loperamide.

Comment: The drug completely eliminated cancer in 16 patients across the Monarch 2 and 3 studies and among patients who have “more concerning characteristics”—such as metastases to the liver, or disease that has returned rapidly—abemaciclib tends to do particularly well.