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Publication Abstract from PubMed

Drug-resistance acquisition through kinase gate-keeper mutations is a major hurdle in the clinic. Here, we determined the first crystal structures of the human FGFR4 kinase domain (FGFR4K) alone and complexed with ponatinib, a promiscuous type-2 (DFG-out) kinase inhibitor, and an oncogenic FGFR4K harboring the V550L gate-keeper mutation bound to FIIN-2, a new type-1 irreversible inhibitor. Remarkably, like ponatinib, FIIN-2 also binds in the DFG-out mode despite lacking a functional group necessary to occupy the pocket vacated upon the DFG-out flip. Structural analysis reveals that the covalent bond between FIIN-2 and a cysteine, uniquely present in the glycine-rich loop of FGFR kinases, facilitates the DFG-out conformation, which together with the internal flexibility of FIIN-2 enables FIIN-2 to avoid the steric clash with the gate-keeper mutation that causes the ponatinib resistance. The structural data provide a blueprint for the development of next generation anticancer inhibitors through combining the salient inhibitory mechanisms of ponatinib and FIIN-2.

DFG-out Mode of Inhibition by an Irreversible Type-1 Inhibitor Capable of Overcoming Gate-Keeper Mutations in FGF Receptors.,Huang Z, Tan L, Wang H, Liu Y, Blais S, Deng J, Neubert TA, Gray NS, Li X, Mohammadi M ACS Chem Biol. 2014 Oct 27. PMID:25317566^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.