P-103 Modulation of Inflammatory and Disease Biomarkers Following 4 Week Treatment with AVX-470, an Oral Anti-TNF Antibody, in Ulcerative Colitis Patients

AVX-470 is an oral, bovine-derived, polyclonal antibody designed to target tumor necrosis factor (TNF) locally in the gastrointestinal tract. TNF is central to the dysregulated inflammatory response in IBD. Injected anti-TNF antibodies are highly effective treatments for IBD but are associated with serious side effects from systemic exposure. In a recent double-blind, placebo-controlled first-in-human trial in patients with active ulcerative colitis (UC), AVX-470 administration was associated with dose-dependent increases in clinical and endoscopic remission. Measurement of pro-inflammatory cytokine levels is essential for proof-of-concept and proof-of-mechanism. The aim of this study was to confirm AVX-470 modulation of inflammatory biomarkers in biopsy tissue and serum, and the mechanistic basis of drug effect. Thirty three (33) male and female adults completed 4 weeks of study drug. AVX-470 (0.2 g/day BID, 1.6 g/day BID, and 3.5 g/day TID) and placebo were formulated as enteric-coated capsules for oral administration. Patients underwent colonoscopy with biopsy from 5 colon regions (cecum/ascending, transverse, descending, sigmoid, rectum) at Baseline and after 4 weeks of dosing, and serum samples were collected at defined time points. Endoscopic activity was assessed by centrally-read UCEIS (Ulcerative Colitis Endoscopic Index of Severity) scoring. TNF levels were measured in colon tissue by immunohistochemistry (IHC) as an indicator of drug effects at the target protein. Additional markers including CRP, IL-6, myeloperoxidase (MPO), and TUNEL staining downstream of TNF were analyzed by ELISA and IHC at Baseline and at Week 4. Changes in markers of inflammation and disease activity were observed in tissue and serum following 4 weeks of AVX-470 treatment. TNF protein levels measured by IHC staining were reduced in colon biopsy tissue from patients in the 3.5g/day dose group at Week 4, confirming direct activity of AVX-470 on the target protein in intestinal tissue. This effect was proportionately greatest in the proximal colon and correlated with both clinical response and the greater reduction of endoscopic inflammatory activity in this bowel segment. Apoptosis in intestinal epithelial cells as measured by TUNEL staining was also reduced in patients from the AVX-470 3.5 g/day dose group at Week 4, particularly in proximal colon. Mean levels of IHC staining for MPO, indicative of neutrophil infiltration, were decreased at Week 4. Levels of serum CRP, a systemic marker of disease, were decreased in the 3.5 g/day treatment group compared to placebo. A dose-dependent reduction in serum IL-6 was also observed with the most pronounced effect in the high dose group compared with placebo. These findings support proof-of-mechanism for AVX-470 mediated reduction of TNF in intestinal tissue, and the potential for AVX-470 to reduce inflammation, intestinal epithelial cell apoptosis, and disease activity in patients with UC through local drug action in the colon. The overall study design of this trial, which integrates tissue, serum, and stool biomarker analysis with safety, pharmacokinetic and immunogenicity endpoints, represents a new paradigm for streamlined drug development in inflammatory bowel disease.