ARRY-142886 is caused by the acquisition of new mutations

Since of the r Central role in the pathophysiology of the JAK2 V617F MPN is a therapeutic target. Several JAK2 inhibitors are currently in development and / or clinical studies for the NPP. Some of these JAK2 inhibitors have also been shown to be remarkably active JAK1 that and, therefore, a potential therapeutic for patients JAK1 mutation positive. One of the most promising inhibitors ARRY-142886 is JAK1/JAK2 INCB018424, 12 currently. In Phase III clinical trials for the NPP The main disadvantage of the tyrosine kinase inhibitor therapy, the development of secondary Ren resistance is caused by the acquisition of new mutations. The best example of this scenario is to BCR ABL-positive tumors. The patients are being treated with imatinib were best Constantly through the acquisition of mutations in the ABL kinase domain.
13 In our laboratory, NPI-2358 we have described one in vitro model of spontaneous conversion of h Hematopoietic function Ethics IL 3 BaF3 cell line growth factor for independent-Dependent clones with constitutive STAT5 activation.14 tumorigenic This model was transformed from the study of BaF3 cells developed with IL 9R m utant lack STAT recruitment site. These BaF3 phe116 almost completely Multiply resistant and failed to activate STAT in response to IL 9.15 However, according to L Through prolonged culture with IL 9 can survive a small number of cells, and even multiply so dependent a cell line Ngig IL 9 selected .14 In contrast to parental BaF3 cells phe116 these selected cells 9 independent IT access-dependent cells after a second selection step in the absence of cytokine can.
These autonomous cells show a cytokine activation of JAK1 and STAT5 independent-Dependent and highly tumorigenic when in M Injected use, which is not the case for parental BaF3 and BaF3 phe116 phe116/9.14, 16 we have previously shown that the upregulation of endogenous JAK1 gene was connected to the first step, n erh namely hte sensitivity of the cells to IL BaF3 phe116 9, and F Promotion of the second stage of the processing, n namely progression independently to cytokine self-dependent BaF3 nome cells.16 In this study, we show that 80% of the autonomous BaF3 Selected clones in our in vitro model hlt, activating point mutations in the kinase Dom acquired JAK1 pseudokinase or ne. JAK1 mutations provide cells with tumorigenic potential by inducing constitutive activation of the JAK STAT, the f their proliferation Promotes independent Dependent.
We used this collection of JAK1 mutation positive autonomous cell lines to study the sensitivity of different JAK1 mutations in the JAK inhibitor. For the first time, we report that mutations of Phe958 and Pro960 not only constitutively active JAK1, but to make the protein mutated JAK1 resistant ATP competitive inhibitors. JAK2 counterpart, n Namely Y931C, also makes JAK2 V617F wild type or mutant resistant to all inhibitors tested ATPcompetitive. Design and methods of cell culture and h Hematopoietic cytokines Ethical BaF3 mouse B cells were cultured in Dulbecco Pro, modified Eagle plea of f Fetal calf serum K And IL 3 transfected CHO cells are cultured. Recombinant human IL 9 was produced in the baculovirus system and purified by affinity Tschromatographie in our laboratory.