The goal of this Phase II project is to advance the development of novel tolerance-inducing peptides (Tregitopes) to prevent and/or treat Type 1 diabetes (T1D) by optimizing the clinical delivery vehicle and treatment protocol, and by identifying correlates of efficacy in preparation for Phase 1 clinical trials. More than 13,000 children in the U.S. are diagnosed with Type 1 Diabetes (T1D) each year. T1D results from destruction of insulin-producing pancreatic islet cells by auto-reactive T cells, eventually leading to glucose intolerance. Induction of antigen (Ag)-specific tolerance is the key to effective immunotherapy for T1D. EpiVax discovered a new biologic intervention for T1D called Tregitopes, which are administered along with insulin peptides in order to reprogram the autoimmune responses and induce islet cell Ag-specific tolerance. On the basis of excellent Phase I results, and parallel collaborative studies demonstrating the induction of Ag- specific tolerance in gene therapy and transplant models, this Phase II project will advance a form of Tregitope therapy called T1D-Ag-Specific Adaptive Tolerance Induction (T1D-ASATI) toward preclinical development. Successful translation of T1D-ASATI to the clinic will have a radical impact on the field of diabetes therapy, potentially abrogating the need for insulin therapy in T1D. Studies in Phase I of this project demonstrated that Tregitopes can both prevent and successfully treat diabetes in NOD mice, when delivered prior to, or at the onset of diabetes, however, the delivery vehicles tested in Phase I are not FDA-approvable. The primary objective of this Phase II project is, therefore, to select a clinically feasible delivery vehicle and regimen; the secondary objective is to define biomarkers or correlates of Tregitope efficacy to support clinical development. Aim 1 will identify a suitable delivery vehicle therapeutic administration route, administration frequency protocol, and dose range for Tregitope therapy in the genetically susceptible non-obese diabetic (NOD) mouse model of T1D. Delivery of either peptides or concatamers composed of the Tregitope and PPI epitopes will be tested in clinically proven vehicles: liposomes, glucan particles, and as a conjugate with recombinant human albumin. Pharmacokinetic and toxicity testing of the final formulation have been included in this revised application, per the review. Aim 2 is devoted to defining key correlates of efficacy associated with the induction of tolerance by Tregitopes in NOD mice, and adaptive tolerance induction in NOD GFP and DO11.10 FoxP3:knock-in mice. Induction of Ag-specific aTregs is an innovative feature of this approach. The long-term goal of this research program is to develop, define, validate and commercialize a novel, first-in-class, safe and effective biological therapy to prevent or treat T1D. We have secured the enthusiastic participation of a regulatory expert (Cavagnaro) and two experienced drug developers (CardioVax, Novozyme) that will support our program. Upon successful completion of the Phase II project, we will be well equipped to enter into pre-INDA discussions with the FDA in preparation for T1D-ASATI Phase I clinical trials.