New treatment options are urgently needed for patients with relapsed chronic 
lymphocytic leukemia (CLL) who fail to respond to currently available therapies 
or cannot achieve a sustained response. Moreover, targeted agents with less 
myelotoxicity are necessary to treat patients with multiple comorbidities who 
would otherwise be unable to tolerate standard regimens. Ibrutinib, a Bruton's 
tyrosine kinase inhibitor, has shown highly encouraging results in phase I/II 
trials in patients with treatment-naive, relapsed and refractory CLL even in the 
presence of high risk disease or poor prognostic markers. In phase I/II trials, 
ibrutinib 420 mg or 840 mg - given continuously as single agent or at a dose of 
420 mg daily in combination with a monoclonal antibody or chemoimmunotherapy - 
has been associated with high response rates and durable clinical remissions. 
Phase II and III trials are currently under way for treatment-naive patients, 
relapsed/refractory patients, and for those patients harboring a 17p deletion.