Telomerase Presentations at the AACR 2007 Annual Meeting.

MENLO PARK, Calif. -- Geron Corporation (Nasdaq:GERN) today referenced multiple presentations on the role of telomerase and telomeres in cancer at this year's American Association for Cancer Research (AACR) Annual Meeting in Los Angeles. There were approximately 80 presentations on telomere and telomerase biology reflecting the growing body of evidence supporting the importance of telomerase as a universal cancer target for drug and vaccine development. Geron holds key intellectual property in the field and leads the development of telomerase-based cancer therapeutics with a drug, GRN163L, and a vaccine, GRNVAC1, in human clinical trials.

Telomerase and Cancer

The opening plenary talk of this year's AACR meeting by Dr. Ronald DePinho, Dana Farber Cancer Institute, entitled "One hundred years of cancer science: Milestones, opportunities, and challenges," highlighted the discovery of telomerase as a landmark in cancer research. Dr. DePinho's own work on manipulating telomerase and growth control genes in mouse models of cancer showed how telomere loss is a tumor suppressive mechanism when growth control genes are generally intact. Telomere shortening in this setting triggers arrest of abnormally dividing cells. However, when certain mutations occur in growth control genes over time due to environmental events or genetic predisposition, critical telomere loss can lead to genomic instability, further mutations, and cancer initiation. In the latter setting, telomerase upregulation quells telomere dysfunction and genomic instability, and confers replicative immortality to highly mutated cells which have the potential to form aggressive tumors. Information in Dr. DePinho's talk and other presentations throughout the AACR meeting on the regulation of telomere dynamics and telomerase activity elucidates the potential for telomerase-inhibiting molecules in the treatment of cancer.

Cancer Stem Cells

Cancer stem cells (CSCs) are a rare sub-population of self-renewing, immortal tumor cells capable of differentiating into the various types of cells seen within the bulk tumor. They are now widely believed to be distinct from the bulk tumor cells and to be responsible for many cases of drug resistance and cancer recurrence. The 2007 AACR meeting had a dramatic increase in CSC presentations, and there is a growing awareness that effective cancer treatment will require drugs that kill CSCs.

At previous cancer meetings, Drs. W. Matsui and R. Jones of Johns Hopkins University reported on telomerase activity in myeloma stem cells. The Johns Hopkins team demonstrated that Geron's telomerase inhibitor, GRN163L, blocked growth and colony formation in both the stem and differentiated subpopulations of myeloma cells. In these studies, no other compounds have been shown to be as active against myeloma CSCs. Geron is currently planning a trial with GRN163L in myeloma patients.

Other Telomerase and Telomere Presentations

Other studies presented at the AACR meeting focused on the degree of telomere loss prior to telomerase activation in various tumor types, the role of telomere dysfunction in tumorigenesis, and use of the telomerase promoter to drive tumor cell death.

"The data presented at AACR contribute to the growing body of evidence regarding the importance of telomerase targeted therapies for the treatment of cancer," noted Alan Colowick, M.D., M.P.H., Geron's president, oncology. "Geron currently has two clinical studies of GRN163L underway in patients with chronic lymphocytic leukemia (CLL) and solid tumor malignancies. We plan to initiate two additional studies of GRN163L in patients with multiple myeloma and non-small cell lung cancer, as well as a study of GRNVAC1 in patients with acute myelogenous leukemia (AML), in the months ahead.

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 telomerase 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 annual report on Form 10-K for the year ended December 31, 2006.