BTK inhibitors in chronic lymphocytic leukemia: a glimpse to the future

The treatment of chronic lymphocytic leukemia (CLL) with inhibitors targeting B cell receptor signaling and other survival mechanisms holds great promise. Especially the early clinical success of Ibrutinib, an irreversible inhibitor of Bruton’s tyrosine kinase (BTK), has received widespread attention. In this review we will focus on the fundamental and clinical aspects of BTK inhibitors in CLL, with emphasis on Ibrutinib as the best studied of this class of drugs. Furthermore, we summarize recent laboratory as well as clinical findings relating to the first cases of Ibrutinib resistance. Finally, we address combination strategies with Ibrutinib, and attempt to extrapolate its current status to the near future in the clinic.