Geron Corporation (Nasdaq:GERN) announced today that the U.S. Patent Office has upheld the validity of a key patent for human embryonic stem cells. The patent is assigned to the Wisconsin Alumni Foundation (“WARF”) and is one of three related patents challenged through reexamination proceedings. Geron holds an exclusive license under these patents to develop and commercialize therapies based on three types of cells derived from human embryonic stem cells: neural cells, cardiomyocytes and pancreatic islet cells.

In communicating its decision, the Patent Office issued an 82 page Action Closing Prosecution in the inter-partes reexamination of U.S. Patent Number 7,029,913. The Patent Office rejected the arguments made by the party that requested the reexamination and found the expert declarations it submitted to be “flawed by hindsight reasoning.” The claims of the patent cover replicating cultures of human embryonic stem cells.

“This is clearly the correct outcome,” said David J. Earp, J.D., Ph.D., Geron’s chief patent counsel and senior vice president of business development. “In the course of the reexamination proceeding, the Patent Office conducted a thorough evaluation of relevant scientific and patent publications, considered extensive legal arguments and reviewed several expert declarations. The decision explains in precise detail why this pioneering technology is entitled to patent protection. We are, of course, pleased with the holding.”

The reexamination proceeding was initiated in October 2006 at the request of New York-based Public Patent Foundation and the California-based Foundation for Taxpayer and Consumer Rights. Two parallel reexamination proceedings involving U.S. Patent Numbers 5,843,780 and 6,200,806 which claim preparations of, respectively, primate and human embryonic stem cells and methods for their isolation, are still pending.

As the world leader in the development of human embryonic stem cell-based therapeutics, Geron holds a broad portfolio of intellectual property rights, including the WARF patents discussed above, additional WARF patents that are not subject to the reexamination proceedings and patents exclusively licensed from the University of California and the University of Oxford. In addition, Geron’s portfolio includes patents and patent applications owned and filed by Geron to cover technologies developed internally by Geron scientists enabling the scalable production and differentiation of human embryonic stem cells. Geron’s stem cell-related patent portfolio includes 36 issued or allowed U.S. patents, 68 patents granted or accepted in other countries and over 130 applications pending worldwide.

Geron is developing first-in-class biopharmaceuticals for the treatment of cancer and chronic degenerative diseases, including spinal cord injury, heart failure and diabetes. The company is advancing an anti-cancer drug and a cancer vaccine that target the enzyme telomerase through multiple clinical trials. Geron is also the world leader in the development of human embryonic stem cell-based therapeutics, with its spinal cord injury treatment anticipated to be the first product to enter clinical development. For more information, visit www.geron.com.

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 statements in this press release regarding potential applications of Geron’s human embryonic stem cell technology and strength of its patent portfolio constitute forward-looking statements that involve risks and uncertainties, including, without limitation, risks inherent in the development and commercialization of potential products, uncertainty of clinical trial results or regulatory approvals or clearances, need for future capital, dependence upon collaborators and 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, 2007.

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info@geron.com