Exhibit 99.1

Geron Receives Milestone Payment from Merck Triggered by IND Filing for
                 Telomerase Cancer Vaccine Candidate

    MENLO PARK, Calif.--(BUSINESS WIRE)--Dec. 12, 2007--Geron
Corporation (Nasdaq:GERN) announced today that Merck & Co, Inc. has
filed an Investigational New Drug application ("IND") with the U.S.
Food and Drug Administration ("FDA") for a cancer vaccine candidate
that targets telomerase. Merck is developing the vaccine under a July,
2005 Research, Development and Commercialization License Agreement
with Geron, which provided Merck with exclusive worldwide rights to
develop and commercialize non-dendritic cell based vaccines targeting
telomerase. Geron has received a $4 million milestone payment from
Merck on account of the IND filing, and is eligible to receive
additional development milestones as well as royalties on worldwide
product sales.

    "We are pleased with the progress that Merck has made in advancing
this program towards the clinic," said Thomas B. Okarma, Ph.D., M.D.,
Geron's president and chief executive officer. "We appreciate the
collaborative nature of our relationship with Merck and look forward
to working with them to realize the therapeutic potential of this
cancer vaccine candidate."

Geron's Dendritic Cell-Based Cancer Vaccine

    Separately, Geron is currently enrolling patients with acute
myelogenous leukemia (AML) in a Phase I/II study of its own telomerase
vaccine candidate, GRNVAC1, which delivers the telomerase antigen
using autologous dendritic cells. In a prior study conducted at Duke
University, the vaccine was shown to induce substantial T-cell
anti-telomerase activity. The Geron study also incorporates a
prime/boost vaccine dosing regimen designed to prolong the period of
anti-telomerase immunity. Geron is also developing a second generation
allogeneic telomerase vaccine based on dendritic cells made from human
embryonic stem cells.

Telomerase and Cancer

    Telomerase is an enzyme, active in most cancer cells, that
maintains telomere length at the ends of chromosomes. This activity
confers replicative immortality to the cells in the tumor, allowing
the cancer to grow and metastasize over long periods of time. Because
telomerase is inactive or only transiently expressed in normal human
tissues, and is critical to the growth and progression of most cancer
types, it is regarded as a universal and specific cancer target.

    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
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 quarterly report on Form 10-Q for the quarter
ended September 30, 2007.

    CONTACT: Russo Partners, LLC
             Media and Investors:
             David Schull, 858-717-2310
             david.schull@russopartnersllc.com
             or
             Russo Partners, LLC
             Tracey Milani, 619-814-3511
             tracey.milani@russopartnersllc.com
             or
             Geron
             David L. Greenwood, 650-473-7765
             Chief Financial Officer
             info@geron.com