Abstract
In an effort to find new pharmacological modalities to overcome resistance to ATP-binding-site inhibitors of Bcr-Abl, we recently reported the discovery of GNF-2, a selective allosteric Bcr-Abl inhibitor. Here, using solution NMR, X-ray crystallography, mutagenesis and hydrogen exchange mass spectrometry, we show that GNF-2 binds to the myristate-binding site of Abl, leading to changes in the structural dynamics of the ATP-binding site. GNF-5, an analogue of GNF-2 with improved pharmacokinetic properties, when used in combination with the ATP-competitive inhibitors imatinib or nilotinib, suppressed the emergence of resistance mutations in vitro, displayed additive inhibitory activity in biochemical and cellular assays against T315I mutant human Bcr-Abl and displayed in vivo efficacy against this recalcitrant mutant in a murine bone-marrow transplantation model. These results show that therapeutically relevant inhibition of Bcr-Abl activity can be achieved with inhibitors that bind to the myristate-binding site and that combining allosteric and ATP-competitive inhibitors can overcome resistance to either agent alone.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Antineoplastic Agents / chemistry*
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Antineoplastic Agents / metabolism
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Antineoplastic Agents / pharmacology*
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Antineoplastic Combined Chemotherapy Protocols
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Benzamides
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Binding Sites
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Bone Marrow Transplantation
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Cell Line, Tumor
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Crystallization
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Disease Models, Animal
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Drug Resistance, Neoplasm / drug effects*
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Female
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Fusion Proteins, bcr-abl / chemistry*
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Fusion Proteins, bcr-abl / genetics
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Fusion Proteins, bcr-abl / metabolism
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Humans
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Imatinib Mesylate
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Inhibitory Concentration 50
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / drug therapy
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / enzymology
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / metabolism*
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Male
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Mass Spectrometry
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Mice
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Models, Molecular
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Mutation / genetics
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Piperazines / chemistry
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Piperazines / pharmacology
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Protein Structure, Tertiary
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Pyrimidines / chemistry
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Pyrimidines / metabolism
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Pyrimidines / pharmacology
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Transplantation, Heterologous
Substances
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Antineoplastic Agents
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Benzamides
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GNF-2 compound
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Piperazines
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Pyrimidines
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abl-bcr fusion protein, human
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Imatinib Mesylate
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Fusion Proteins, bcr-abl
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nilotinib