The prognosis of patients with relapsed acute myeloid leukemia (AML) harboring FLT3 mutations is extremely poor. We have demonstrated that microenvironment/leukemia interactions play a major role in the chemoresistance of leukemic stem cells and that the SDF-1a/CXCR4 axis is a key regulator of this interaction. We recently discovered that Sorafenib is a superb FLT3-ITD inhibitor with high clinical single agent activity, including complete remissions in Phase I studies 1,2. High CXCR4 levels are associated with poor prognosis4, and FLT3 mutations upregulate CXCR45. We recently reported that inhibition of CXCR4 with an analogue of the FDA approved CXCR4 inhibitor AMD3100( Plerixafar) resulted in mobilization of leukemic cells and sensitization to the pro-apoptotic effects of Sorafenib6. G- CSF cleaves SDF-1, down-regulates CXCR4, was found to be highly synergistic with AMD3100 in mobilization hematopoietic stem cells9 and was recently approved by FDA. We have reported that AML patients in remission, who were treated with AMD3100/G-CSF, had massive egress of AML cells into the circulation, providing first proof of principle for leukemia cell mobilization10. In addition, we observed preferential mobilization of AML over normal cells, both in AML patients in CR and in patients with active disease who received AMD3100/G-CSF as part of a preparative regimen followed by SCT, further supporting the validity of this therapeutic concept. Of note, Sorafenib has no toxicity against normal hematopoietic cells. Based on these findings, we propose to test the hypothesis that mobilization of leukemic stem cells by disruption of SDF-1a/CXCR4 by AMD3100/G-CSF results in improved anti-leukemia activity of Sorafenib in AML patients with mutant FLT3. In addition, we will study the effects of this targeted therapy on non-mobilized AML blasts. We will conduct a clinical trial to determine the safety and efficacy of AMD3100, G-CSF and escalating doses of the FLT3-ITD inhibitor Sorafenib in patients with AML harboring FLT3-ITD mutations and study the in vivo biological effects of disrupting SDF-1a/CXCR4 interactions by AMD3100/G-CSF. Patients with FLT3-ITD mutations can have variable numbers of cells with three distinct FLT3 genotypes : heterozygous FLT3-ITD, homozygous FLT3-ITD and wild type FLT3. Therefore, we will also determine, by single-cell PCR, the effects of this therapy against cells carrying these genotypes, during mobilization with AMD3100/G-CSF and following treatment with sorafenib. Taken together, these studies will establish the safety and anti-leukemia activity of AMD3100/G- CSF/sorafenib and provide a comprehensive assessment of mechanisms involved in leukemia cell mobilization and inhibition of cell signaling.

Public Health Relevance

Acute myelogenous leukemia is a mostly fatal disease, in particular in patients whose leukemia cells are characterized by a mutation in the FLT3 gene. We have recently found, that the drug Sorafenib, which is FDA approved for certain other cancers, is a superb inhibitor of cells carrying this mutation, resulting in complete clearance of leukemia cells from the blood and a reduction in bone marrow leukemia cells. We are proposing to combine sorafenib with a blocker of the chemokine receptor CXCR4, AMD3100(Plerixafor), in a clinical trial in relapsed/refractory patients with AML carrying the FLT3-ITD mutation with the aim of determining the safety and efficacy of this approach.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21CA143805-02
Application #
8056055
Study Section
Clinical Oncology Study Section (CONC)
Program Officer
Merritt, William D
Project Start
2010-04-05
Project End
2014-03-31
Budget Start
2011-04-01
Budget End
2014-03-31
Support Year
2
Fiscal Year
2011
Total Cost
$312,240
Indirect Cost
Name
University of Texas MD Anderson Cancer Center
Department
Internal Medicine/Medicine
Type
Other Domestic Higher Education
DUNS #
800772139
City
Houston
State
TX
Country
United States
Zip Code
77030
Zhang, Weiguo; Ly, Charlie; Ishizawa, Jo et al. (2018) Combinatorial targeting of XPO1 and FLT3 exerts synergistic anti-leukemia effects through induction of differentiation and apoptosis in FLT3-mutated acute myeloid leukemias: from concept to clinical trial. Haematologica 103:1642-1653
Zhang, Weiguo; Borthakur, Gautam; Gao, Chen et al. (2016) The Dual MEK/FLT3 Inhibitor E6201 Exerts Cytotoxic Activity against Acute Myeloid Leukemia Cells Harboring Resistance-Conferring FLT3 Mutations. Cancer Res 76:1528-37
Reinisch, Andreas; Etchart, Nathalie; Thomas, Daniel et al. (2015) Epigenetic and in vivo comparison of diverse MSC sources reveals an endochondral signature for human hematopoietic niche formation. Blood 125:249-60
Zhang, Weiguo; Gao, Chen; Konopleva, Marina et al. (2014) Reversal of acquired drug resistance in FLT3-mutated acute myeloid leukemia cells via distinct drug combination strategies. Clin Cancer Res 20:2363-74
Zhang, Weiguo; Ruvolo, Vivian R; Gao, Chen et al. (2014) Evaluation of apoptosis induction by concomitant inhibition of MEK, mTOR, and Bcl-2 in human acute myelogenous leukemia cells. Mol Cancer Ther 13:1848-59
Chen, Ye; Jacamo, Rodrigo; Konopleva, Marina et al. (2013) CXCR4 downregulation of let-7a drives chemoresistance in acute myeloid leukemia. J Clin Invest 123:2395-407
Battula, V Lokesh; Chen, Ye; Cabreira, Maria da Graca et al. (2013) Connective tissue growth factor regulates adipocyte differentiation of mesenchymal stromal cells and facilitates leukemia bone marrow engraftment. Blood 122:357-66
Chen, Ye; Jacamo, Rodrigo; Shi, Yue-xi et al. (2012) Human extramedullary bone marrow in mice: a novel in vivo model of genetically controlled hematopoietic microenvironment. Blood 119:4971-80