Chronic myeloid leukemia (CML) is a hematopoietic stem cell disorder and currently treated by BCR/ABL tyrosine kinase inhibitors such as Imatinib, Dasatinib and Nilotinib. Clinical relapses are common and pose great challenge for successful tyrosine kinase inhibitor (TKI) therapy. Mutations in the ABL kinase domain are the principal mechanism of Imatinib resistance (IMR). The second-generation BCR/ABL inhibitors Nilotinib and Dasatinib effectively inhibit IMR variants, but are ineffective against the gatekeeper mutant, T315I. Mutation of the gatekeeper residue mediates broad-spectrum drug resistance and is a common mechanism of resistance across tyrosine kinase inhibitor therapy such as ABL, KIT, SRC, PDGFRA, PDGFRB and EGFR. Recently, we have characterized the gatekeeper mutations in these kinases and discovered that the substitution of a bulky hydrophobic residue for the gatekeeper threonine activates the kinase by stabilizing the """"""""hydrophobic spine"""""""" assembled during the active state. We proposed that the next-generation inhibitor should disrupt the assembly of active state and stabilize the inactive state. This work has led us to develop third-generation ABL kinase inhibitors, AP24163, AP24534 and GNF-5. Given our data and experiences with first and second-generation inhibitors, it is likely that resistance to third-generation inhibitors will develop as well. Recently we have shown that the third-generation inhibitor AP24163 - the parent compound of the clinical agent AP24534 - specifically selects for compound mutations in ABL kinase to which we do not have any therapeutic option. This proposal is aimed to identify drug resistant mutations against third generation clinical inhibitors AP24534 (Ponatinib). Compound mutations are mostly presented from the allosteric sites of the ABL kinase. This proposal is aimed to study the mechanism employed by the compound mutations to confer resistance and to develop strategies to target the allosteric sites by small molecule allosteric inhibitors. Towards this end we have identified a unique hydrophobic module- hydrophobic girdle-that governs kinase regulation. We anticipate that a detail characterization of this hydrophobic-motif will help us in developing new allosteric inhibitors tha can be used in combination with ATP- competitive inhibitors to suppress all forms resistant mutations.

Public Health Relevance

Protein kinase inhibitor therapy has emerged as one of the most successful strategy for the treatment of cancers. Chronic myeloid leukemia is hematologic malignancy and treated by kinase inhibitors. However, in the course of the clinical use of these inhibitors, many patients relapse and resistant to treatment posed challenge to cure this disease. Point mutations in the kinase domain mostly cause resistant to inhibitors. This proposal is aimed to develop curative therapeutic response in CML using combination of kinase inhibitors targeting catalytic and allosteric sites.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
Project #
Application #
Study Section
Drug Discovery and Molecular Pharmacology Study Section (DMP)
Program Officer
Misra, Raj N
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Cincinnati Children's Hospital Medical Center
United States
Zip Code
Wang, Jieyu; Hayashi, Yoshihiro; Yokota, Asumi et al. (2018) Expansion of EPOR-negative macrophages besides erythroblasts by elevated EPOR signaling in erythrocytosis mouse models. Haematologica 103:40-50
Dwivedi, Pankaj; Muench, David E; Wagner, Michael et al. (2018) Time resolved quantitative phospho-tyrosine analysis reveals Bruton's Tyrosine kinase mediated signaling downstream of the mutated granulocyte-colony stimulating factor receptors. Leukemia :
Kesarwani, Meenu; Kincaid, Zachary; Azam, Mohammad (2017) MEK/ERK addiction in CNL/aCML. Oncotarget 8:99215-99216
Rohrabaugh, S; Kesarwani, M; Kincaid, Z et al. (2017) Enhanced MAPK signaling is essential for CSF3R-induced leukemia. Leukemia 31:1770-1778
Kesarwani, Meenu; Kincaid, Zachary; Gomaa, Ahmed et al. (2017) Targeting c-FOS and DUSP1 abrogates intrinsic resistance to tyrosine-kinase inhibitor therapy in BCR-ABL-induced leukemia. Nat Med 23:472-482
Kesarwani, Meenu; Huber, Erika; Kincaid, Zachary et al. (2015) Targeting substrate-site in Jak2 kinase prevents emergence of genetic resistance. Sci Rep 5:14538
Kesarwani, Meenu; Huber, Erika; Kincaid, Zachary et al. (2014) A method for screening and validation of resistant mutations against kinase inhibitors. J Vis Exp :
Kesarwani, M; Huber, E; Azam, M (2013) Overcoming AC220 resistance of FLT3-ITD by SAR302503. Blood Cancer J 3:e138
Azam, Mohammad (2012) An in vitro screening to identify drug-resistant mutations for target-directed chemotherapeutic agents. Methods Mol Biol 928:175-84