Myxoma virus (MV) infects only rabbits in vivo, but also has a natural capacity to infect a wide variety of human cancer cells in vitro and in vivo. Thus, MV is an attractive candidate for oncolytic virotherapy to treat human cancer. MV has been used to successfully treat several diverse human brain cancers in xenografted immunodeficient mice and murine metastatic melanoma in immunocompetent mice. Here, MV will be developed for human clinical trials by exploiting a therapeutic strategy for which the virus is uniquely well- suited: ex vivo purging of cancer cells within human bone marrow or mobilized-PBMC samples from patients who would normally be excluded from autologous stem cell transplantation following high dose chemotherapy. Considerable preliminary data has been collected to support this proposal: 1) MV does not perturb or compromise human multipotent stem cell differentiation in immunodeficient mice engrafted with normal human bone marrow or cytokine-mobilized PBMCs, 2) MV eliminates a wide variety of human cancer cells following ex vivo purging, 3) MV can effectively purge not only permissive leukemia/lymphoma cells in vivo, but also unexpectedly prevents even nonpermissive human leukemia cells (such as KG1 cells) from engraftment or tumor induction, and 4) MV recombinants that express a variety of useful reporter proteins (fluorescent and bioluminescent) for imaging purposes have already been constructed. Specifically, our aims are: 1) Validate MV safety for ex vivo treatment of normal human hematopoietic stem cells: The safety of MV-purging for normal human stem cell differentiation will be tested, using engrafted immunodeficient NOG mice to verify full hematopoietic cell engraftment and immune reconstitution. MV purging will be tested on primary human stem/progenitor cells derived from normal bone marrow and G-CSF-mobilized PBMCs, using hematopoietic colony forming cell assays in vitro as well as for efficient hematologic cell engraftment in vivo. 2) Optimize MV ex vivo cancer cell purging: Two human cancers, B-cell lymphoma and acute myeloid leukemia, will be investigated for the ability of ex vivo MV purging to eliminate their tumorigenic potential in vivo in engrafted NOG mice. The cancer cells and viruses will be tagged with distinguishable luciferases that allow the engrafted tumor cells and the therapeutic virus to be independently tracked in vivo. Primary cells from acute myeloid leukemia patients will also be tested for the ability of MV to specifically eliminate the contaminating cancer cells and allow the selective engraftment of only noncancerous human leukocytes. 3) Investigate the mechanism of MV purging of primary human leukemia cells: We have recently shown that ex vivo infection of human KG1 leukemia cells with MV prevents the subsequent engraftment and tumor formation of these cells into NOG recipient mice, despite the fact that these cells are completely nonpermissive for MV infection in vitro. To assess for virus-induced cell signaling changes, we probed MV-infected KG1 cells with an array of antibodies to 46 different human signaling phosphoproteins, and observed that MV infection specifically induces Stat5 and Hck activation in KG1 cells. We will explore the functional significance of these host cell signaling activations for the successful ex vivo tumor cell purging of human leukemia calls by MV.

Public Health Relevance

Recently, we discovered that one particular rabbit-specific poxvirus, called myxoma virus (MV), also infects and kills a wide spectrum of human cancer cells and MV has been used to successfully treat several types of cancers in animal models. In order to facilitate the preclinical development of MV as a new oncolytic therapeutic for cancer in man, we propose to exploit two specific cancer models (human B-cell lymphoma and acute myeloid leukemia) to establish the optimal conditions for a novel therapeutic cancer cell purging protocol. This strategy will benefit leukemia/lymphoma cancer patients who are currently excluded from autologous bone marrow transplantation by allowing their own stem cell samples (from bone marrow or blood) to be purged of cancer cells prior to re-engraftment and reconstitution of their immune system following high dose chemotherapy.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA138541-04
Application #
8413599
Study Section
Developmental Therapeutics Study Section (DT)
Program Officer
Yovandich, Jason L
Project Start
2010-03-01
Project End
2014-12-31
Budget Start
2013-01-07
Budget End
2013-12-31
Support Year
4
Fiscal Year
2013
Total Cost
$277,176
Indirect Cost
$87,977
Name
University of Florida
Department
Genetics
Type
Schools of Medicine
DUNS #
969663814
City
Gainesville
State
FL
Country
United States
Zip Code
32611
Villa, Nancy Y; Bais, Swarna; Chan, Winnie M et al. (2016) Ex vivo virotherapy with myxoma virus does not impair hematopoietic stem and progenitor cells. Cytotherapy 18:465-80
McKenzie, Brienne A; Zemp, Franz J; Pisklakova, Alexandra et al. (2015) In vitro screen of a small molecule inhibitor drug library identifies multiple compounds that synergize with oncolytic myxoma virus against human brain tumor-initiating cells. Neuro Oncol 17:1086-94
Villa, Nancy Y; Wasserfall, Clive H; Meacham, Amy M et al. (2015) Myxoma virus suppresses proliferation of activated T lymphocytes yet permits oncolytic virus transfer to cancer cells. Blood 125:3778-88
Chan, Winnie M; McFadden, Grant (2014) Oncolytic Poxviruses. Annu Rev Virol 1:119-141
Bell, John; McFadden, Grant (2014) Viruses for tumor therapy. Cell Host Microbe 15:260-5
Zemp, Franz J; McKenzie, Brienne A; Lun, Xueqing et al. (2014) Cellular factors promoting resistance to effective treatment of glioma with oncolytic myxoma virus. Cancer Res 74:7260-73
Lemos de Matos, Ana; McFadden, Grant; Esteves, Pedro J (2014) Evolution of viral sensing RIG-I-like receptor genes in Leporidae genera Oryctolagus, Sylvilagus, and Lepus. Immunogenetics 66:43-52
Haller, Sherry L; Peng, Chen; McFadden, Grant et al. (2014) Poxviruses and the evolution of host range and virulence. Infect Genet Evol 21:15-40
Doty, Rosalinda A; Liu, Jia; McFadden, Grant et al. (2013) Histological evaluation of intratumoral myxoma virus treatment in an immunocompetent mouse model of melanoma. Oncolytic Virother 2:1-17
Sallam, Mohamed F; Al Ahmed, Azzam M; Abdel-Dayem, Mahmoud S et al. (2013) Ecological niche modeling and land cover risk areas for rift valley fever vector, culex tritaeniorhynchus giles in Jazan, Saudi Arabia. PLoS One 8:e65786

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