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Stressgen Granted U.S. Patent Covering Therapeutic Products to Treat Hepatitis B Virus
  -- New Patent Strengthens Intellectual Property Estate Surrounding Platform for CoVal(TM) Fusions --
SAN DIEGO, CA, Sept. 7 2005- Stressgen Biotechnologies ("The Company") (TSX: SSB - News) announced today that the U.S. Patent and Trademark Office granted Patent Number 6,921,534 covering fusion protein compositions comprised of a hepatitis B virus (HBV) antigen fused to a heat shock protein (Hsp), as well as DNA encoding such fusion proteins, and methods of treating an HBV infection using these fusion proteins. The company pipeline report says early research is ongoing for HCV, herses simplex, cervical dysplasia/HPV-related diseases, and other diseases.
Preclinical data from the Company's therapeutic vaccine for hepatitis B, HspBcor, another CoVal(TM) fusion candidate, demonstrate that mice immunized with the HspBcor fusion protein activate cellular immunity by generating cytotoxic T lymphocytes (CTLs), peptide-specific white blood cells that can recognize and kill infected cells expressing the HBV core antigen. This CTL activity was triggered in normal mice that have been genetically modified to contain components of a human immune system, and also in HBV-transgenic mice that express the entire HBV genome.
"In individuals with chronic HBV infection, viral persistence may be related to an insufficient HBV-specific killer T cell (CTL) response," said Marvin I. Siegel, Ph.D., Stressgen's Executive Vice President of Research and Development. "A major hurdle for the development of an effective therapeutic vaccine for HBV is the presumptive existence in many clinical situations of immune tolerance for the HBV antigens. The immunity demonstrated in our animal model is significant because it demonstrates effective immunity in the face of preexisting tolerance."
HBV-transgenic mice are commonly employed as a model of chronic HBV infection. Transgenic mice that are immunologically tolerant to HBV normally do not rid themselves of cells expressing viral antigens. This tolerance is similar to what is observed in humans suffering from chronic HBV infection. Nevertheless, a single injection of HspBcor has been observed to break immune tolerance to the HBV core antigen in some of these transgenic mice by eliciting a specific CTL response, one of the hurdles to an effective therapeutic vaccine for HBV.
About Hepatitis B (HBV):
Hepatitis B is the most common serious liver infection in the world. It is caused by the hepatitis B virus that infects liver cells and can lead to liver failure, cirrhosis or cancer of the liver. Despite the availability of safe and effective preventative vaccines, there are still more than 350 million people worldwide chronically infected with the virus, according to the World Health Organization. Without intervention, each year as many as one million of these individuals will die from HBV-induced disease such as cirrhosis and cancer. According to the Centers for Disease Control and Prevention, more than 1.25 million Americans are chronically infected with HBV, along with 78,000 new infections reported in 2001.
According to the Hepatitis B Foundation, HBV is 100 times more infectious than the AIDS virus. For the 350 million people worldwide who are already chronic carriers of HBV, the existing preventative vaccine, as currently used, is of no therapeutic value.
About Stressgen Biotechnologies Corporation
Stressgen, a biopharmaceutical company, focuses on the discovery, development and commercialization of innovative therapeutic vaccines for the treatment of infectious diseases and cancer. The corporation is publicly traded on the Toronto Stock Exchange under the symbol SSB.
About CoVal(TM) Fusion Proteins
Stressgen capitalizes upon the immunostimulatory powers of heat shock proteins utilizing recombinant technology to fuse, or covalently link, a stress protein with a protein antigen to create a single hybrid protein designed to trigger the immune system to recognize that antigen. For more information about CoVal(TM) fusion technology, or Stressgen, please visit the website located at www.stressgen.com.
Stressgen Biotechnologies Corporation is a biopharmaceutical company focused on the discovery, development and commercialization of innovative stress protein-based immunotherapeutics, also known as therapeutic vaccines. These therapeutic vaccines are created using the Company’s proprietary CoVal™ fusion product technology, which covalently link stress proteins (also known as heat shock proteins) to disease specific antigens. The Company’s lead candidate, HspE7, targets a broad spectrum of human papillomavirus (HPV) related diseases. The Company has also initiated research studies or is evaluating other CoVal™ fusion product candidates for the treatment of hepatitis B, herpes simplex, and Hepatitis C. Further, Stressgen has an internationally recognized bioreagents business which sells reagents (chemicals) to scientists studying cellular stress, apoptosis, oxidative stress and neurobiology.
This press release contains forward-looking statements that are subject to risks and uncertainties, including those about plans to develop HspBcor for hepatitis B. The actual results may differ materially from the expectations contained in our forward-looking statements due to factors including our need for additional capital. Please refer to our filings with Canadian securities regulators for more information on these and other applicable risks.
For further information
Donna D. Slade, Director, Investor Relations, 6055 Lusk Boulevard, San Diego, CA, USA, 92121, Tel: (858) 202-4900, Fax: (858) 450-6849, dslade@stressgen.com
Source: Stressgen Biotechnologies Corp.
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