Ligand-Assisted Delivery of Immunoregulatory Agents to Dystrophic Muscle for Repeat Dosing of AAV-Dystrophin Gene Therapy
Abstract
Recombinant adeno-associated virus (rAAV)-microdystrophin gene therapy has tremendous potential to cure Duchenne muscular dystrophy (DMD). Recent clinical studies have shown that a substantial portion of DMD patients harness a population of T cells that specifically target dystrophin. Additionally, several gene therapy trials have shown that an immune response is also developed to the rAAV vector, the system used to deliver microdystrophin to muscle. These immune responses are predicted to neutralize or eliminate the AAV vector and muscle cells in which dystrophin expression has been restored. These antigen-specific immune responses raise concern with respect to the safety of rAAV-microdystrophin gene therapy in DMD patients and ability to repeat dosing if necessary. The long-term goal of our research is to determine if AAV and dystrophin immune responses limit the efficacy and long-term stability of AAV micro-dystrophin gene therapy, and leverage our expertise in regulatory T cell (Treg) biology and protein chemistry to inhibit these responses. An important distinction from other studies is that our approach will target Tregs to tolerize patients to dystrophin, so that lifelong treatment with immunosuppressive drugs and side-effects associated with their chronic use are avoided. The immediate objective of the current study is to determine whether muscle-specific delivery of an experimental therapy that induces Tregs suppresses rAAV and dystrophin immunity to improve the efficacy of rAAV-microdystrophin gene therapy and its repeat dosing. We will test the overarching hypothesis that Tregs suppress dystrophin- and rAAV-specific T cells, which we predict hinder the ability of the AAV vector system to deliver its therapeutic payload (i.e., dystrophin) to myofibers and prevent repeat dosing. We will test this hypothesis by addressing two specific aims: (1) determine whether Tregs suppress dystrophin- and AAV-specific T cells, and (2) use a ligand-assisted, muscle-specific delivery of a single-agent IL-2c to suppress antigen-specific T cells and permit repeat dosing. We will use immunization methods we optimized to induce AAV capsid- and dystrophin-specific T cells in mice prior to gene therapy. This model of experimentally induced AAV and dystrophin immunity will be used to determine if antigen-specific T cells impair the delivery of dystrophin and/or long-term stability of myofibers modified by the rAAV-microdystrophin gene therapy. To determine if Tregs suppress dystrophin- and AAV capsid-specific T cells we will deplete Tregs using genetic tools or increase Tregs with a humanized single-agent IL-2/anti-IL-2 antibody complex (IL-2c). In prior work we demonstrated that mouse versions of IL-2c ameliorated the severity of muscular dystrophy in a mouse model of DMD. An innovative chemistry will be used to tether single-agent IL-2c with a dystroglycan-alpha-specific antibody to enable the specific delivery of IL-2c to muscle in which dystrophin and the dystrophin glycoprotein complex has been restored by rAAV-microdystrophin gene therapy. We will also compare this to systemic treatment by using single-agent IL-2c alone to determine if localized or systemic treatment is more efficacious. We anticipate that the tethered IL-2c will enhance the suppression of dystrophin- and AAV-specific T cells, leading to improved myofiber transduction and long-term, stable expression of dystrophin in our mouse model of experimentally induced AAV and dystrophin immunity. The proposed project is expected to make an important and original contribution toward our understanding of the role of dystrophin-specific and AAV-specific T cells in DMD patients. Further, our proposed studies are strongly poised to develop a novel and effective immunoregulatory therapy that addresses the unmet need for a safer alternative to broad immunosuppression (i.e., chronic glucocorticoid therapy). The human single-agent IL-2c used in this study is non-immunogenic and c
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 05, 2021
- Source ID
- W81XWH2110891
Entities
People
- Sergio Villalta
Organizations
- United States Army
- University of California, Irvine