Acquisition Enhances OnCore’s Portfolio of Oral HBV Compounds With a Surface Antigen (s-antigen, or HBsAg) Secretion Inhibitor Program and a Second Capsid Assembly Inhibitor Program

DOYLESTOWN, PA, USA I October 1, 2014 I OnCore Biopharma, Inc. (“OnCore” or the “Company”), a biotechnology company focused on the research, development and commercialization of oral treatments for chronic hepatitis B virus (HBV) infection, announced today an all-cash transaction to acquire all outstanding shares of Enantigen Therapeutics, Inc. (“Enantigen”), a privately-held pharmaceutical company. Through the acquisition, OnCore will assume development of Enantigen’s two novel discovery programs, one targeting inhibition of s-antigen secretion and one targeting capsid assembly inhibition.

“We are very proud of the discovery work that we have done in Hepatitis B,” commented Dr. Xiaodong Xu, Enantigen’s President and Chief Operating Officer. “We believe that OnCore is in the best position to rapidly advance our programs into human clinical trials, and we look forward to joining the OnCore research team to help realize their vision.”

“Our plan is to combine Enantigen’s drug candidates with our existing all-oral portfolio of HBV compounds and advance multiple combination regimens into human clinical trials,” stated Patrick Higgins, OnCore’s Chief Executive Officer. “The Enantigen programs, together with our lead cyclophilin inhibitor, NPV018, and our cccDNA formation and capsid assembly inhibition programs give OnCore the most comprehensive platform of assets consolidated to target a cure for hepatitis B.”

About Surface Antigen Secretion Inhibitors

HBV surface antigen is one of the key viral proteins that plays an essential role in controlling the host immune response. HBsAg exists in large quantities not only as a constituent of HBV virions, but also in HBV subviral particles, which significantly outnumber infectious virions circulating in the body. HBsAg has been shown to inhibit the innate immune response through effects on T-cell and dendritic cell function. The inhibition of HBsAg production or secretion holds the promise of reducing the impact of the viral infection on host immune function.

About Capsid Assembly Inhibitors

cccDNA transcription produces HBV pregenomic RNA (pgRNA), to which is covalently bound the HBV viral polymerase. This complex must be encapsidated by a sphere of viral capsid proteins to continue the viral lifecycle, producing more virus particles and enabling the replenishment of cccDNA in the nucleus of hepatocytes. Inhibiting pgRNA encapsidation effectively terminates the progression of the virus lifecycle and inhibits viral replication.

About Hepatitis B

Hepatitis B is a serious infection of the liver caused by the hepatitis B virus (HBV) and is considered a major global health problem. Hepatitis B infection can cause chronic liver disease, which increases a patient’s risk of death from liver cirrhosis and liver cancer. Estimates from the Centers for Disease Control and Prevention (CDC) indicate that up to 350 million people globally may be chronically infected with hepatitis B and, according to the World Health Organization (WHO), more than 780,000 people die every year due to hepatitis B. Most currently-available therapies aim to suppress this viral infection but do not lead to a cure in the overwhelming majority of patients. Identifying a functional or complete cure for hepatitis B infection remains a significant area of unmet medical need.

About Enantigen

Enantigen Therapeutics, Inc. is a privately-held pharmaceutical company committed to the discovery, development and commercialization of novel drugs to treat life-threatening infectious diseases. Enantigen’s primary focus is on the development of oral therapeutics for the treatment of HBV. Enantigen is located at the Pennsylvania Biotechnology Center in Doylestown, Pennsylvania.

About OnCore

OnCore Biopharma, Inc. is a privately held biotechnology company focused on the research, development, and commercialization of therapies for the treatment of chronic hepatitis B virus (HBV) infection. The Company was founded by former executives of Pharmasset, Inc., which was acquired by Gilead Sciences in January 2012.

OnCore has assembled a portfolio of novel product candidates with unique mechanisms of action for the treatment of hepatitis B and is focused on delivering a cure. It is widely believed that eradicating covalently closed circular DNA (cccDNA) in HBV-infected hepatocytes represents the ultimate solution for curing chronic hepatitis B infected patients. OnCore is currently addressing an all-oral, permanent HBV cure by targeting cccDNA with the goal of achieving a “functional cure,” wherein the risk of death from liver disease due to HBV is the same as that in a person with a naturally resolved infection. OnCore is combining agents against cccDNA with other novel direct acting antiviral mechanisms and strategies that engage host immune response. OnCore believes that combination therapy will be required to achieve complete eradication of HBV from the liver.

OnCore is located at the Pennsylvania Biotechnology Center in Doylestown, Pennsylvania, which is also home to the Hepatitis B Foundation and the Foundation’s research center, the Baruch S. Blumberg Institute.

SOURCE: OnCore Biopharma