Pharmacyclic’s (now AbbVie) Imbruvica® (ibrutinib) is an anticancer drug targeting B-cell malignancies. It blocks a specific protein called Bruton’s tyrosine kinase (BTK). Imbruvica was originally developed and approved in late 2013 by the US FDA to treat patients with mantle cell lymphoma, a rare blood cancer, impacting fewer than 3,000 people a year. Under an accelerated approval process, it was approved in February 2014 for the treatment of chronic lymphocytic leukemia (CLL), a form of non-Hodgkin’s lymphoma. The initial and conditional CLL approval was revised in mid-2014 after additional data demonstrated its safety and efficacy, for patients that had tried one or more prior treatments unsuccessfully. In January 2015, Imbruvica was approved by the FDA for treatment of Waldenström’s macroglobulinemia, and in March, 2016 it was approved for first-line treatment of CLL.