In this issue of Blood, Jebaraj et al1 characterize a novel Bruton tyrosine kinase (BTK) inhibitor, vecabrutinib, that targets mutant BTK C481S and wild-type BTK in preclinical models. This is the first BTK inhibitor that also inhibits interleukin-2-inducible T-cell kinase (ITK) and can still bind to mutant BTK.