Arrowhead Research Corporation (NASDAQ: ARWR), a targeted therapeutics company, today announced that a study of its RNAi-based candidate ARC-520 in a chimpanzee chronically infected with the human hepatitis B virus (HBV) supports findings from rodent models indicating that it can knock down HBV DNA and key viral antigens. Dr. Robert Lanford and his team at the Texas Biomedical Research Institute are conducting the study. The chimpanzee being treated has had chronic HBV for over 30 years, has high viral-titer and antigenemia, and nearly 100% of hepatocytes stain positive for HBV. Studies are ongoing and additional data will be discussed when the company hosts an analyst and investor event on March 25, and at upcoming scientific conferences. “It’s encouraging to see data from our preclinical rodent models confirmed in a true primate disease setting,” said Bruce Given, MD, Arrowhead’s COO and Head of R&D. “There are very few high primates that develop chronic HBV. We understand these studies to be useful predictors of the response we might expect in human patients as we approach clinical trials later this year.” Investors and analysts may access the live presentation on March 25 on the Arrowhead Research website at www.arrowheadresearch.com or by calling 1.888.771.4371 (US toll free) or 1.847.585.4405 (US toll) and using the confirmation number: 34474854. The webcast will also be available for 90 days following the event. About Arrowhead Research Corporation Arrowhead Research Corporation is a clinical stage targeted therapeutics company with development programs in oncology, obesity, and chronic hepatitis B virus infection. The company is leveraging its platform technologies to design and develop peptide-drug conjugates (PDCs) that specifically home to cell types of interest while sparing off-target tissues, create targeted drugs based on the gene silencing RNA interference (RNAi) mechanism, and work with partners to create improved versions of traditional small molecule drugs.