Pharmacodynamic analyses of BTK and ITK from peripheral blood samples. (A) IgE-induced basophil activation. Activated basophils (CD123⁺, HLA-DR⁻, CD63⁺) from 32 patients are shown as a percentage of total basophils (CD123⁺, HLA-DR⁻). (B) PLCγ1 activation in CD4 T cells as measured by phosphorylation of Y783 (in red), as well as ITK occupancy (in blue) from 4 patients. Treatment day and hour post–ibrutinib administration are denoted as day number (D) − hour (0 or 4); 0 hour denotes a predose sample.