1 Modulation of inflammatory processes in DSS-induced colitis model versus gastrointestinal acute radiation syndrome with AVX-470m, an oral polyclonal anti-TNF antibody Kailash C Bhol, Ph.D, Brenda Lemos, B.S, Emma Erlich, B.A., David Keane, B.S, Daniel E. Tracey, Ph.D., Barbara S. Fox, Ph.D., and Deborah Hartman, Ph.D. CCFA 2013

2 Disclosures Employee of Avaxia Biologics, Inc.

3 Introduction AVX-470 is a gut-targeted polyclonal anti-TNF antibody that is orally delivered and acts locally in the GI tract 1 AVX-470 is being developed for inflammatory bowel disease (IBD), and for gastrointestinal acute radiation syndrome (GI ARS) as a secondary indication Designed to overcome the limitations of current injectable anti-TNF therapies –direct delivery to the site of inflammation –minimal systemic exposure for reduced side effects from untargeted immunosuppression –potential for prolonged duration of effect by avoiding neutralizing anti-drug antibodies 1 Bhol et al, Inflamm Bowel Dis Oct;19(11):

4 Background AVX-470m is a murine-specific surrogate antibody 1 –Potent and selective, neutralizes mouse TNF –Effective in DSS- and TNBS- induced colitis models TNF is strongly implicated in GI ARS, which results from exposure to high doses of ionizing radiation –GI ARS results from a nuclear accident, explosion, accidental release or act of terrorism; devastating consequences in GI tract driven by cytokine-mediated inflammation closely resembling the pathophysiology of IBD In this study, we have profiled AVX-470m effects on biomarkers of inflammation in IBD and GI ARS models. 1 Bhol et al, Inflamm Bowel Dis Oct;19(11):

5 GI ARS: structural damage and mortality curve AVX-470m treatment showed survival benefit in the GI ARS model, compared to saline and control Ig.

6 DSS-induced colitis vs GI ARS: Induction of inflammatory biomarkers Biomarkers measured by immunohistochemistry, and qPCR (*) Colitis: C57BL/6 mice with 3% DSS in drinking water for five days GI ARS: C57BL/6 mice irradiated with 15.9 Gy, partial bone marrow shielding, 60 Co gamma radiation source Biomarker Response to injury DSS-induced colitis (colon) GI ARS (jejunum) TNF↑↑ TNFR1 *↑─ TNFR2 *↑↑ MPO↑↑ MMP9 *↑↑ CD3↑─ CD68↑─ IL-1β↑↑ IL-12p40↑─ ICAM-1 *↑↑ ↑ indicates: Significant increase over control in DSS colitis (p<0.05) Or, > 2-fold increase in GI ARS

7 Treatment with AVX-470m reduces TNF levels in both IBD and GI ARS models GI ARS - jejunum tissue sections IBD - colon tissue sections AVX-470m (10 mg/day, BID by oral gavage) reduced TNF protein levels in GI tissue in both IBD and GI ARS models No DSS DSS + Saline DSS + AVX-470m No Radiation15.9 Gy + Saline 15.9 Gy + AVX-470m

8 AVX-470m treatment reduces inflammatory biomarkers in both IBD & GI ARS models Biomarker Response to injury+ AVX-470m DSS-induced colitis (colon) GI ARS (jejunum) DSS-induced colitis (colon) GI ARS (jejunum) TNF↑↑↓↓ TNFR1*↑─── TNFR2*↑↑── MPO↑↑↓↓ MMP9*↑↑↓↓ CD3↑─── CD68↑─↓─ IL-1B↑↑↓─ IL-12p40↑─↓─ ICAM-1 (qPCR)↑↑── ↓ indicates p 2-fold decrease for GI ARS markers. Control Ig had no effect on inflammatory biomarkers. *= qPCR analysis.

9 AVX-470m penetrates GI mucosal barrier Tissue sections stained for presence of bovine Ig AVX-470m penetrates into damaged tissue in both colon and jejunum, but not healthy tissue. Labeling is seen in mucosa, lamina propria, and submucosal regions. Minimal systemic exposure is seen with AVX-470m Control animal with AVX-470mDSS with AVX-470m 15.9 Gy with AVX-470m NormalIBD model - colonGI ARS model - jejunum

10 Conclusions DSS colitis and GI ARS share a common TNF- mediated inflammatory component AVX-470m is a novel gut-targeted anti-TNF antibody that is delivered orally and acts locally in the GI tract Oral delivery of AVX-470m effectively inhibits TNF expression in DSS colitis and GI ARS These data support the therapeutic potential of an oral anti-TNF antibody as a gut-targeted treatment for multiple GI inflammatory diseases in both the large and small bowel. AVX-470 is in Phase 1b clinical trials in patients with active ulcerative colitis, results in early 2014.

11 Acknowledgments DSS-induced colitis model Biomodels, LLC –Steve Sonis, DMD, DMSc –Greg Lyng, PhD GI ARS model CiToxLAB North America –Simon Authier, PhD Avaxia Biologics, Inc. –Barbara Fox, PhD –Dan Tracey, PhD –Kailash Bhol, PhD –Brenda Lemos –Emma Erlich –Dave Keane This project has been funded in part by the Biomedical Advanced Research and Development Authority (BARDA), Office of the Assistant Secretary for Preparedness and Response, Department of Health and Human Services under Contract No. HHSO C. This work has also been supported in part by in part by National Institutes of Health (NIH) grant 2R44DK