Ibrutinib dose was sequentially decreased from the standard dose in CLL of 420 mg down to 140 mg by cycle 3. Mean plasma and intracellular ibrutinib levels as well as target occupancy were determined showing that target occupancy was maintained at >97% at all levels. ns, not significant. The figure has been adapted from Figures 1 and 2 in the article by Chen et al that begins on page 2249. Professional illustration by Patrick Lane, ScEYEnce Studios.