Phase I Clinical Trial of Islet Antigen–Specific Plasmid Coexpressing Tolerogenic Proteins Demonstrates Safety in Adults With Type 1 Diabetes

Antigen-specific therapy is needed to induce tolerance in type 1 diabetes at early disease stages or in combination with immunotherapy. We conducted a phase I trial in type 1 diabetes of a novel plasmid construct expressing the islet antigen preproinsulin (PPI) and immunomodulatory cytokines transforming growth factor-β1 (TGF-β1), interleukin-10 (IL-10), and IL-2. The therapy was safe and well tolerated. Dose-dependent changes in DNA plasmid levels and type 1 interferon signatures were detected; however, global and antigen-specific immune changes to PPI, IL-2, IL-10, or TGF-β1 were not observed. Further trials are needed to assess efficacy.