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Characterization of compound 584, an Abl kinase inhibitor with lasting effects.

Research paper by Miriam M Puttini, Sara S Redaelli, Loris L Moretti, Stefania S Brussolo, Rosalind H RH Gunby, Luca L Mologni, Edoardo E Marchesi, Loredana L Cleris, Arianna A Donella-Deana, Peter P Drueckes, Elisa E Sala, Vittorio V Lucchini, Michael M Kubbutat, Franca F Formelli, Alfonso A Zambon, et al.

Indexed on: 28 Mar '08Published on: 28 Mar '08Published in: Haematologica



Abstract

Resistance to imatinib is an important clinical issue in the treatment of Philadelphia chromosome-positive leukemias which is being tackled by the development of new, more potent drugs, such as the dual Src/Abl tyrosine kinase inhibitors dasatinib and bosutinib and the imatinib analog nilotinib. In the current study we describe the design, synthesis and biological properties of an imatinib analog with a chlorine-substituted benzamide, namely compound 584 (cmp-584).To increase the potency, we rationally designed cmp-584, a compound with enhanced shape complementarity with the kinase domain of Abl. cmp-584 was synthesized and characterized in vitro against a panel of 67 serine/threonine and tyrosine kinases using radioactive and enzyme-linked immunosorbent kinase assays. We studied inhibitory cellular activity using Bcr/Abl-positive human cell lines, murine transfectants in proliferation experiments, and a murine xenotrans-planted model. Kinase assays on isolated Bcr/Abl protein were also performed. Finally, we used a wash-out approach on whole cells to study the binding kinetics of the inhibitor.cmp-584 showed potent anti-Abl activity both on recombinant protein (IC(50): 8 nM) and in cell-based assays (IC(50): 0.1-10 nM). The drug maintained inhibitory activity against platelet-derived growth factor receptors and c-KIT and was also active against Lyn (IC(50): 301 nM). No other kinase of the panel was inhibited at nanomolar doses. cmp-584 was 20- to 300-fold more active than imatinib in cells. This superior activity was evident in intact cells, in which full-length Bcr-Abl is present. In vivo experiments confirmed the activity of cmp-584. Wash-out experiments showed that short exposure to the drug impaired cell proliferation and Bcr-Abl phosphorylation for a substantially longer period of time than imatinib.The present results suggest a slower off-rate (dissociation rate) of cmp-584 compared to imatinib as an explanation for the increased cellular activity of the former.

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