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Old 09-14-2020, 12:09 PM   #3
Senior Member
Join Date: Oct 2013
Posts: 470
Re: Rapid Breast Cancer Disease Progression Following Cyclin Dependent Kinase 4 and 6

I read the two articles that Nguyen posted. I saw something very interesting in the second one. When they compared the time to progression when using the anti-estrogen drug alone, it was 10 months. With the combo of Palbociclib plus the estrogen inhibitor it 20 months time to progression.This seems pretty dramatic evidence pointing to the fact that CyclinD 4/6 inhibitors are extremely effective drugs.

Things are not that dramatic when you look at the important thing OVERALL SURVIVAL. With the Estrogen inhibitor it was 33 months. With the ibrance/ER inhibitor combo it was 37 months. If the increase in Time to progression correlated well with overall survival yuld expect 60 months overall survival. The fact is, time to progression increase correlates little with overall survival. When multiple drugs are used together, you often get increases in TTP with the combo but actual decreases in the overall survival, probably due to the increased toxicity of the combination therapy. It seems the FDA is using increases in the time to progression to approve new anticancer drugs. Maybe I misread something. Ill reread the pharmacy journal article and do some more research.

Of the 3 commonly used CDK-4,6 inhibitors, Abemicliclib or versenio seems to have less severe neutropenia.

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