Patel, Ravi
(2019)
SRC-FAMILY KINASES IMPACT PROGNOSIS AND TARGETED THERAPY IN FLT3-ITD+ ACUTE MYELOID LEUKEMIA.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Acute myelogenous leukemia (AML) is a disease characterized by undifferentiated bone-marrow progenitor cells dominating the bone marrow. Currently the five-year survival rate for AML patients is 27.4 percent. Meanwhile the standard of care for most AML patients has not changed for nearly 50 years. We now know that AML is a genetically heterogeneous disease and therefore it is unlikely that all AML patients will respond to therapy the same way. Upregulation of protein-tyrosine kinase signaling pathways is one common feature of some AML tumors, offering opportunities for targeted therapy. Important examples include activating mutations in the FLT3 receptor or overexpression of SRC-family kinases expressed in myeloid cells (HCK, FGR, LYN). Inhibition of HCK with the pyrrolopyrimidine kinase inhibitor A-419259 reversed AML cell bone marrow engraftment in patient-derived xenograft mice. Here we show that A-419259 inhibits not only HCK but also FGR, LYN and FLT3 bearing an activating internal tandem duplication (ITD). To investigate the relationship of FLT3, HCK and FGR to the A-419259 response, we generated TF-1 human myeloid cell populations expressing FLT3-ITD either alone or in combination with HCK or FGR. FLT3-ITD alone sensitized TF-1 cells to growth arrest by A-419259, supporting direct action on the FLT3 kinase domain. Cells transformed with inhibitor-resistant FLT3-ITD mutants (D835Y, F691L) were insensitive to A-419259, while co-expression of wild-type HCK or FGR with these FLT3 mutants restored inhibitor sensitivity. Expression of HCK or FGR mutants with engineered A-419259 resistance also decreased inhibitor sensitivity of TF-1/FLT3-ITD cells. To investigate how resistance to A-419259 evolves de novo, we developed populations of FLT3-ITD+ AML cell lines via long-term dose escalation. Whole exome sequencing identified only a single FLT3-ITD kinase domain mutation (N676S) among all A-419259 target kinases in each of six independent resistant cell populations. Thus, the anti-AML activity of A-419259 involves inhibition of FLT3-ITD, HCK and FGR, suggesting that clinical inhibitors targeting all three kinases may enhance efficacy while reducing the probability of acquired resistance.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
20 November 2019 |
| Date Type: |
Publication |
| Defense Date: |
31 May 2019 |
| Approval Date: |
20 November 2019 |
| Submission Date: |
25 August 2019 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
236 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
School of Medicine > Molecular Pharmacology |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Acute Myeloid Leukemia
Fgr
Flt3
Hck
ITD
Lyn |
| Date Deposited: |
20 Nov 2019 15:47 |
| Last Modified: |
20 Nov 2020 06:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/37405 |
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