A cure for HIV is an important goal of HIV treatment. Various kick and kill strategies have been envisioned to eradicate the HIV-infected cells that persist during antiretroviral therapy. However, there are few therapeutic interventions that specifically kill HIV-infected cells. Our preliminary data demonstrates that T-cells engineered to express anti-HIV chimeric antigen receptors (CAR) can effectively kill HIV infected cells. CAR were first described 25 years ago, and early clinical trials of adoptive transfer of CAR-expressing T-cells for a variety of malignancies, as well as for HIV, showed promise but their efficacy was limited by insufficient function and/or off-target toxicity. Current trials of newer CR, engineered to incorporate intracellular co-stimulatory domains, have shown dramatic clinical benefit against specific malignancies. CAR-based strategies are attractive for HIV because CAR T-cells function independently of major histocompatibility complexes, and therefore can target HIV-infected cells that have escaped the host immune response. CAR-expressing T-cells have also been shown to persist for years, providing a potential long-term strategy to target HIV-infected cells that reactivate in the future. Most previous anti-HIV CAR used CD4 as a broadly reactive ligand for HIV. However in recent years the breadth and potency of available HIV antibodies has improved significantly. We hypothesize that newer anti-HIV CAR, which include intracellular co-stimulatory domains, linked to the single chain variable fragment (scFv) of potent HIV antibodies, will be an effective strategy for targeting the residual HIV reservoir. We expect these CAR to be more specific for HIV-expressing cells than anti-HIV CAR that utilize CD4 as the ligand for HIV. A concern with any CAR-based approach for HIV is that the CAR+ T-cells can be infected with HIV. Our data indicates that protecting the CAR+ T-cells from HIV infection by disrupting CCR5 increases the efficacy of anti-HIV CAR+ T-cells. This project has two specific aims: 1. Optimize the potency and breadth of an antibody-based anti-HIV CAR by screening scFv from several different antibodies; optimizing the length of the linker between the variable region of the antibody and the transmembrane domain; and testing combinations of CAR targeting different epitopes. 3. Test the efficacy of the optimized CAR(s) in a small animal model of HIV latency. Together these results will help optimize an antibody-based anti-HIV CAR and provide important insight into the feasibility and effectiveness of this strategy.

Public Health Relevance

More than 30 million people are infected with HIV. A cure for HIV will likely require new therapeutic strategies to specifically kill the residual HIV-infected clls that persist during antiretroviral therapy. This project seeks to optimize 'chimeric antigen receptors' to target HIV-infected cells and test the approach in a small animal model of HIV infection.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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AIDS Discovery and Development of Therapeutics Study Section (ADDT)
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Sanders, Brigitte E
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Seattle Children's Hospital
United States
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Hale, Malika; Mesojednik, Taylor; Romano Ibarra, Guillermo S et al. (2017) Engineering HIV-Resistant, Anti-HIV Chimeric Antigen Receptor T Cells. Mol Ther 25:570-579
Romano Ibarra, Guillermo S; Paul, Biswajit; Sather, Blythe D et al. (2016) Efficient Modification of the CCR5 Locus in Primary Human T Cells With megaTAL Nuclease Establishes HIV-1 Resistance. Mol Ther Nucleic Acids 5:e352