Chronic myeloid leukemia (CML) is a hematopoietic malignancy characterized by a (9;22) translocation, which generates the constitutively active BCR-ABL1 tyrosine kinase. BCR-ABL1 is the critical mediator of disease pathogenesis, exhibiting constitutive kinase activity that drives survival and proliferation through multiple downstream pathways. While therapy with the ABL1 kinase inhibitor imatinib leads to durable responses in the majority of patients with chronic phase CML, a substantial number of patients develop resistance to therapy, and transient responses are the rule for patients with more advanced disease. Resistance is commonly due to acquired point mutations in the BCR-ABL1 kinase domain, and the second-generation ABL1 inhibitors nilotinib, dasatinib, bosutinib, and ponatinib are largely effective salvage therapies in this therapeutic scenario. However, recent clinical reports suggest that sequential treatment with single agent ABL1 kinase inhibitor therapy can select for BCR-ABL1 compound mutants (two mutations within the same BCR-ABL1 molecule) that confer high-level resistance to multiple inhibitors. In vitro biochemical and cell-based resistance screens, along with crystallographic studies, will be used to better characterize and determine treatment strategies for controlling BCR-ABL1 compound mutations and to minimize the risk of their emergence. Beyond BCR-ABL1 kinase domain mutations, a subset of patients exhibit disease progression via BCR-ABL1 kinase-independent mechanisms, the underlying causative molecular events of which are considerably more heterogeneous and have not been comprehensively characterized. The combination of functional screens using panels of small- molecule inhibitors with whole exome and RNA sequencing analysis will be used to accelerate the identification of molecular mechanisms of BCR-ABL1 kinase-independent resistance. Lastly, despite the utility of ABL1 kinase inhibitor therapies in the management of CML, growing evidence suggests that inhibition of BCR-ABL1 kinase activity in CML stem cells is insufficient to eliminate these cells, thus requiring even the best responding patients to remain on therapy life-long. To develop strategies for selectively targeting CML disease persistence, small-molecule inhibitor-based combinations simultaneously blocking BCR-ABL1 and either bolstering phosphatase activity or inhibiting MEK/ERK-regulated auxiliary signaling will be evaluated in primary CML specimens using a variety of ex vivo cellular, biochemical, and flow cytometric methods. Thus, this proposal centers on: 1) establishment of strategies for controlling and preventing the emergence of highly-resistant BCR-ABL1 compound mutations, 2) elucidation of molecular lesions and therapeutically actionable pathways mediating BCR-ABL1 kinase-independent resistance, and 3) evaluation of mechanisms to selectively eliminate persistent CML stem cells. This knowledge will inform and improve the disease management for patients with CML and other malignancies.

Public Health Relevance

Targeted therapy for chronic myeloid leukemia (CML) with imatinib (Gleevec) has dramatically altered the prognosis for patients with this disease, but resistance to imatinib occurs in some patients and residual disease, requiring life-long therapy, persists even in the best responders. The proposed studies will improve our understanding of and ability to control resistance, aid in the design of novel treatment strategies to selectively target residual leukemic stem cells, and provide further insight into the biology of the disease. Together, these findings will have important implications for the treatment of CML and for the use of targeted therapies in many other cancers.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA065823-25
Application #
10075235
Study Section
Basic Mechanisms of Cancer Therapeutics Study Section (BMCT)
Program Officer
Forry, Suzanne L
Project Start
1995-07-01
Project End
2021-12-31
Budget Start
2021-01-01
Budget End
2021-12-31
Support Year
25
Fiscal Year
2021
Total Cost
Indirect Cost
Name
Oregon Health and Science University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
096997515
City
Portland
State
OR
Country
United States
Zip Code
97239
Mitchell, Rebecca; Hopcroft, Lisa E M; Baquero, Pablo et al. (2018) Targeting BCR-ABL-Independent TKI Resistance in Chronic Myeloid Leukemia by mTOR and Autophagy Inhibition. J Natl Cancer Inst 110:467-478
Zabriskie, Matthew S; Antelope, Orlando; Verma, Anupam R et al. (2018) A novel AGGF1-PDGFRb fusion in pediatric T-cell acute lymphoblastic leukemia. Haematologica 103:e87-e91
Pietarinen, Paavo O; Eide, Christopher A; Ayuda-DurĂ¡n, Pilar et al. (2017) Differentiation status of primary chronic myeloid leukemia cells affects sensitivity to BCR-ABL1 inhibitors. Oncotarget 8:22606-22615
Watanabe-Smith, Kevin; Godil, Jamila; Agarwal, Anupriya et al. (2017) Analysis of acquired mutations in transgenes arising in Ba/F3 transformation assays: findings and recommendations. Oncotarget 8:12596-12606
Ma, Leyuan; Boucher, Jeffrey I; Paulsen, Janet et al. (2017) CRISPR-Cas9-mediated saturated mutagenesis screen predicts clinical drug resistance with improved accuracy. Proc Natl Acad Sci U S A 114:11751-11756
Zabriskie, M S; Eide, C A; Yan, D et al. (2016) Extreme mutational selectivity of axitinib limits its potential use as a targeted therapeutic for BCR-ABL1-positive leukemia. Leukemia 30:1418-21
O'Hare, Thomas; Zabriskie, Matthew S; Eide, Christopher A et al. (2011) The BCR-ABL35INS insertion/truncation mutant is kinase-inactive and does not contribute to tyrosine kinase inhibitor resistance in chronic myeloid leukemia. Blood 118:5250-4
Eide, Christopher A; Adrian, Lauren T; Tyner, Jeffrey W et al. (2011) The ABL switch control inhibitor DCC-2036 is active against the chronic myeloid leukemia mutant BCR-ABLT315I and exhibits a narrow resistance profile. Cancer Res 71:3189-95
Johnson, Kara J; Griswold, Ian J; O'Hare, Thomas et al. (2009) A BCR-ABL mutant lacking direct binding sites for the GRB2, CBL and CRKL adapter proteins fails to induce leukemia in mice. PLoS One 4:e7439
Snead, Jennifer L; O'Hare, Thomas; Adrian, Lauren T et al. (2009) Acute dasatinib exposure commits Bcr-Abl-dependent cells to apoptosis. Blood 114:3459-63

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