Geron Corporation Obtains U.S. Patent for Drug Screening Using Human Embryonic Stem Cell-Derived Hepatocytes.

Business Editors/Health/Medical Writers

MENLO PARK, Calif.--(BUSINESS WIRE)--Jan. 14, 2003

Geron Corporation (Nasdaq:GERN) announced today that it has been issued U.S. Patent No. 6,506,574, covering the use of hepatocytes derived from human embryonic stem cells (hESCs) for drug screening. This is the second U.S. patent issued to Geron Corporation covering hESC-derived hepatocytes.

The patented discovery comes from Geron's programs to commercialize hESCs both for research and therapeutic uses. Embryonic stem cells have the potential to differentiate into any cell type in the body. Scientists at Geron have discovered methods to produce uniform populations of a number of important cell types. Examples are neural cells for Parkinson's disease and spinal cord injury, cardiomyocytes for heart disease, and islet cells for diabetes. Hepatocytes are the primary functional cell type in the liver. They maintain the nutrient balance in blood, and remove metabolites and toxic substances that are dangerous to the body. They are also responsible for the metabolism of most pharmaceutical drugs.

This new patent protects technology that is being developed by Geron's Research and Development Technology (RDT) Business Unit. The RDT business was created to capitalize on the commercial potential of embryonic stem cells as research tools for drug discovery. Such applications are likely to be among the first commercial applications of hESC technology.

"The use of hepatocytes for drug screening is a cornerstone of our RDT business model," said Melissa A. Kelly, Geron's vice president of Corporate Development and General Manager of RDT. "Embryonic stem cells can be grown almost indefinitely in culture, and can generate a limitless supply of human hepatocytes. This meets a long-standing need of major pharmaceutical manufacturers. Drugs being developed for almost any therapeutic purpose are screened early on for toxicity and metabolic effects on the liver. However, availability of primary human hepatocytes is very limited, so drug companies must do their testing using rodent cells, or human liver tissue of variable quality. Geron's technology can provide the industry with a reliable and scalable source of human hepatocytes that have standardized characteristics. Our technology will enable the hepatic toxicity and metabolic profile of new drugs under development to be determined in vitro, prior to the initiation of human clinical trials."

"We now have patent protection for both the production of hepatocytes from hESCs (U.S. Patent No. 6,458,589 issued to Geron on October 1, 2002) and their implementation by the end-user in pharmaceutical testing," said David J. Earp, J.D., Ph.D., Geron's vice president of Intellectual Property. "hESC-derived cells having characteristic features of hepatocytes are combined with the test compound, and then the user detects any effect the compound has on the cells as well as the specific metabolites of the compound generated by the cells. The patent explicitly covers toxicity screening, effects on cell growth and metabolism, and effects on various components of the cytochrome p450 system, which is used by the liver to metabolize drugs."

Geron is a biopharmaceutical company focused on developing and commercializing therapeutic and diagnostic products for applications in oncology and regenerative medicine, and research tools for drug discovery. Geron's product development programs are based upon three patented core technologies: telomerase, human embryonic stem cells, and nuclear transfer.

This news release may contain forward-looking statements made pursuant to the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. Investors are cautioned that such forward-looking statements in this press release regarding future applications of Geron Corporation's technology constitute statements involving risks and uncertainties, including, without limitation, risks inherent in the development and commercialization of potential products, regulatory approvals and clearances, and the maintenance of our intellectual property rights. Actual results may differ materially from the results anticipated in these forward-looking statements. Additional information on potential factors that could affect our results and other risks and uncertainties are detailed from time to time in Geron's periodic reports, including the quarterly report on Form 10-Q for the quarter ended September 30, 2002.