There has been recent discussion of the proper dosing dosing of ibrutinib in CLL.
I have posted an important discussion of this topic on my blog: bkoffman.blogspot.com
A few key points.
The dose for CLL in almost all cases in 3 of 140 mg caps a day, for MCL it is 4.
With less than that, we may not be saturating the cysteine-481 site and that may encourage resistance. That is why it is usually a bad idea to start at a low dose and titrate up with drugs like ibrutinib.
There is a fuller discussion on my blog with references.