Summary
The Bruton’s tyrosine kinase protein is expressed in most hematopoietic cells with the exception of T cells and natural killer cells, but the selective effect of Bruton’s tyrosine kinase mutations suggests that its primary functional role is in antigen receptor signalling in B cells. Ibrutinib (=PCI-32765) was designed as a selective and irreversible inhibitor of the Bruton’s tyrosine kinase protein. In vitro, PCI-32765 arrested cell growth and induced apoptosis in human B-cell lymphoma cell lines, and inhibited tumour growth in vivo in xenograft models. A first analysis performed on 116 naive chronic lymphocytic leukaemia patients with a median age of 71 (range: 65 – 84) shows an estimated 22-months progression-free survival rate of 96%; the median progression-free survival or overall survival had not been reached.1 In 61 patients with relapsed/ refractory chronic lymphocytic leukaemia/small lymphocytic lymphoma with a median age of 64 years (range: 40 – 81) and a high-risk cohort (24 patients), the estimated 22-months progression-free survival rate for the 85 relapse/refractory and high-risk patients was 76%. PCI-32765 (ibrutinib) has demonstrated promising activity in studies enrolling older patients with treatment-naive or relapsed/refractory chronic lymphocytic leukaemia and older patients with small lymphocytic lymphoma. Randomised phase III studies in naïve chronic lymphocytic leukaemia/small lymphocytic lymphoma patients are currently on-going.
(BELG J HEMATOL 2013;4(3): 102–105)
