[~Albert--Dekker--aldekker@ ] fair point. You'll probably never see a publication that says an approved regimen is intolerable--these agents are usually killed in early drug development. I also agree that Abemaciclib is not a walk in the park. How do you handle GI side effects? I have found often that the starting 150mg BID dose requires modification relatively quickly due to diarrhea and GI side effects, even with good supportive anti-diarrheal medications. Even moreso in the adjuvant setting (a la MonarchE), where the "preventative" nature of treatment may also contribute to early discontinuation.

This study confirms my practice--diarrhea in 95% of patients! But generally lower grade and managed with Imodium and dose reduction/treatment breaks. Interesting that no one discontinued due to diarrhea.

This paper again raises the potential differences in tolerance based on race/ethnicity (the CREATE-X data using capecitabine 1250mg/m2 BID in a primarily Japanese/Korean population comes to mind--I seldom am able to use any dose higher than 1000mg/m2 in my primarily Caucasian/Black patients).

I honestly not seen any publication recently that stated that something not tolerable. I have patients on Verzenio and it is definitely not walk in the part.

Key Points
• Source: Cancer Management and Research
• Conclusion: “Abemaciclib was well tolerated in Japanese patients in MONARCH 2 and MONARCH 3, with common, clinically relevant TEAEs [treatment-emergent adverse effects] manageable with appropriate interventions."
• The current study assessed the nature/treatment of 3 common adverse effects in Japanese women enrolled in global studies examining abemaciclib plus hormone therapy in advanced HR+, HER2- breast cancer.
• In participants taking abemaciclib, diarrhea, neutropenia, and increased liver enzymes were common. These adverse effects were particularly common in Japanese vs. global populations. These adverse events were typically limited and could be managed by decreasing/stopping abemaciclib dosing or using other agents.
• “These results indicate that abemaciclib plus hormone therapy is generally safe to use in Japanese women with HR+, HER2- advanced breast cancer,” wrote the authors. “The information learned may improve how common side effects of abemaciclib are managed in Japanese women.”
• One limitation of the current study was the small sample size of Japanese patients.
• Genetic, pharmacogenetic, tumor-biology, and dietary factors could have changed responses in Asian vs. other populations.