SCID-Xl is catastrophic immunodeficiency disorder caused by mutations within the common gamma chain (?c) gene. While stem cell transplantation using a matched sibling donor can be curative, most patients lack optimal donors leading to poorer outcomes. Gene replacement has many theoretical advantages as an alternative therapeutic approach for SCID-Xl;and pioneering clinical studies using gammaretroviral ?c delivery lead to both significant benefit as well as unanticipated adverse events due to viral enhancer triggered leukemogenesis. The overarching hypothesis of this PPG is that both the efficacy and safety of ?c gene delivery can be significantly improved using recombinant foamy virus (FV) based vectors. Studies in Project 1 are designed to test the hypotheses that yc FV vectors devoid of viral enhancers (with or without additional enhancer blocking elements flanking the transcriptional cassette) will exhibit levels of transgene expression sufficient for functional rescue in vivo while concurrently showing reduced genotoxicity.
The aims of Project 1 are designed to test these hypotheses via detailed phenotypic, functional, and molecular analysis in both: 1) a small animal model of SCID-Xl and 2) hematopoietic stem cells (HSC) derived from SCID-Xl patients. Our specific studies will include efficacy and safety assessment of 1) EFIa-hu-?c FV vectors in vivo in myeloablated vs. non-myeloablated murine SCID-Xl recipients;and in alternative in vitro transactivation assays;2) Preclinical and GMP-grade 1st generation ?c FV in transduced SCID-Xl patient CD34* BM cells;and 3) Candidate insulated 2nd generation ?c FV vectors in HSC from SCID-Xl mice and human patients. Project 1 will utilize all 4 Cores and will interface on multiple levels with work within both Projects 2 and 3. In conjunction with data derived from Projects 2 and 3, our studies will provide key data regarding efficacy, safety and optimal vector design for future 1st and 2nd generation SCID-Xl FV vector clinical trials.

Agency
National Institute of Health (NIH)
Type
Research Program Projects (P01)
Project #
5P01AI097100-03
Application #
8712350
Study Section
Special Emphasis Panel (ZAI1)
Project Start
Project End
Budget Start
Budget End
Support Year
3
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Seattle Children's Hospital
Department
Type
DUNS #
City
Seattle
State
WA
Country
United States
Zip Code
98121
Beard, Brian C; Adair, Jennifer E; Trobridge, Grant D et al. (2014) High-throughput genomic mapping of vector integration sites in gene therapy studies. Methods Mol Biol 1185:321-44
Burtner, Christopher R; Beard, Brian C; Kennedy, Douglas R et al. (2014) Intravenous injection of a foamy virus vector to correct canine SCID-X1. Blood 123:3578-84
Wang, Cathy X; Sather, Blythe D; Wang, Xuefeng et al. (2014) Rapamycin relieves lentiviral vector transduction resistance in human and mouse hematopoietic stem cells. Blood 124:913-23
Powers, John M; Trobridge, Grant D (2013) Effect of fetal bovine serum on foamy and lentiviral vector production. Hum Gene Ther Methods 24:307-9
Olszko, Miles E; Trobridge, Grant D (2013) Foamy virus vectors for HIV gene therapy. Viruses 5:2585-600