BTK resynthesis rate and occupancy in PBMCs. (A) BTK resynthesis in patients with CLL (n = 48) and healthy volunteers (n = 4), shown as mean ± standard error of the mean (SEM). Linear regression was used to calculate slopes for the return of free BTK. Heathy volunteers received a 100-mg dose.⁸  (B) Individual BTK occupancy in the BID group and the QD group over the first 12 months of treatment. The median values are represented by the horizontal lines. *P < .05, **P < .01, ****P < .0001. (C) Individual BTK occupancy in patients before and a median of 3 months (range, 0.5-6) after switching from 200 mg QD to 100 mg BID.