Project Summary Inflammatory bowel disease is a group of disorders (Crohn’s disease and Ulcerative Colitis) that are associated with substantial morbidity and disability for millions of people worldwide. Although multiple biologic agents and small molecules are approved for the treatment, anti-TNF monoclonal antibodies remain first line therapy. Yet, clinical benefit from these agents is lost in ~30% of patients due to neutralizing anti-drug antibodies (ADAs). Systemic administration results in immunosuppression with heightened risk for serious infections. Efforts to develop gut-restricted oral anti-TNF antibodies (for convenience and to avoid systemic toxicity) have shown treatment benefit but have not been clinically feasible due to the high doses required to overcome proteolytic gut enzyme digestion. DBT178 is a trimerized 14 D-amino acid cyclic peptide that binds with exceptional affinity to the TNF trimer. It blocks both soluble and membrane-bound TNF activity and is 400-fold more potent than the leading TNF mAb, adalimumab (Humira®), in vitro. D-peptides are chiral mirror images of natural L-peptides; thus, they are essentially inert to enzymatic proteolysis and are stable over a broad pH range. Thus, orally administered DBT178 should transit intact to sites of IBD (jejunum, ileum and colon), permitting clinically effective dosing. In addition, DBT178 has ~5% the mass of therapeutic anti-TNF mAbs and should have a greater penetration from gut luminal mucosa to submucosal tissues. Oral DBT178 is expected to minimize absorption from gut to portal and systemic circulation (thereby limiting potential systemic toxicity), and its resistance to proteolytic antigen processing will reduce the potential for developing neutralizing anti-DBT178 antibodies. The goal of this Phase I SBIR is to demonstrate DBT178 efficacy following oral delivery in two mouse models of colitis. However, since this inhibitor binds human TNF, but not mouse TNF it will not be effective in conventional IBD models. Accordingly, Aim 1 optimizes DBT178 for oral delivery and tests its inhibition of GI toxicity and systemic inflammation following a single IP injection of high dose hTNF. Aim 2 tests oral DBT178 delivery in a specialized model of DSS-induced acute colitis using B-hTNFA mice, where the human TNFα gene is expressed under normal physiological control following its insertion into the deleted mouse TNF locus. This work plan has a 1-year timeline.