Geron Corporation (Nasdaq:GERN) today announced the presentation of research studies indicating that GRNOPC1, the company’s human embryonic stem cell (hESC)-based therapeutic for the treatment of spinal cord injury, evades a direct attack by the human immune system.

Presented by Geron scientist Ross Okamura at the Federation of Clinical Immunology Societies meeting in San Diego, the findings could mean that patients treated with GRNOPC1 would require significantly lower doses and/or shorter courses of immunosuppression than what are required for patients who undergo solid organ transplants.

“The results imply that our cell-based therapeutic, unlike traditional solid organ transplants, is minimally recognized by the human immune system,” said Thomas B. Okarma, Ph.D, M.D., Geron’s president and chief executive officer. “Because GRNOPC1 cells are allogenic, it was expected that they would be recognized and destroyed by multiple immune rejection modulators. This isn’t the case. The benefit to patients is that a reduction in the requirement for immunosuppression decreases the potential for untoward side effects that are common with those types of drugs.”

The data indicate that GRNOPC1 cells have low susceptibility to both direct cell and antibody-mediated immune responses. The data also show that GRNOPC1 cells do not widely express non-human antigens, such as Neu5GC, that might have originated from mouse feeder cells to which the original hESC cell line was exposed in its initial derivation. Expression of such non-human antigens would typically lead to lysis by antibodies present in the sera of normal individuals.

In the studies, GRNOPC1 cells were tested for susceptibility to both immune effector cells and sera from normal healthy individuals. GRNOPC1 cells stimulated very low levels of T cell proliferation. Allogenic T cell proliferation is a standard measure of immune recognition of foreign transplanted tissue. Even when GRNOPC1 cells were exposed to proinflammatory cytokines, such as γ interferon or TNFα, allogeneic T cell proliferation was not induced.

In addition, GRNOPC1 cells were not lysed by natural killer cells, the “innate” arm of the immune system. Finally, GRNOPC1 cells were largely resistant to killing by antibodies present in the sera of normal healthy individuals. Sera from eight of 10 individuals failed to induce the killing of GRNOPC1 cells. The sera from the remaining two individuals induced only 10% GRNOPC1 cell lysis.

GRNOPC1 is an allogeneic population of cells containing oligodendroglial progenitors that is intended for transplantation into the lesion site of patients with spinal cord injury to induce tissue repair. Geron’s development plan for the product calls for the filing of an Investigational New Drug (IND) Application with the U.S. Food and Drug Administration later this year pending the outcome of ongoing safety studies.

Geron is developing first-in-class biopharmaceuticals for the treatment of cancer and chronic degenerative diseases, including spinal cord injury, heart failure, diabetes and HIV/AIDS. 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 such forward-looking statements in this press release regarding potential applications of Geron’s human embryonic stem cell technology 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 March 31, 2007.