Geron Corporation is a biotechnology company located in Menlo Park, California, which specializes in developing and commercializng therapeutic products for cancer that inhibit telomerase.

Geron, based in Menlo Park, California, was founded by gerontologist Michael D. West, now CEO of BioTime, who secured initial venture capital investment in the company from Kleiner Perkins Caufield & Byers and Venrock. The company was incorporated in 1990 and began doing business in 1992. John A. Scarlett was appointed CEO in 2011.

The company's Scientific and Clinical Advisory Board has included Nobel laureates James Watson, Gunter Blobel, and Carol Greider, and Leonard Hayflick, known for discovering that human cells divide for a limited number of times in vitro (called the Hayflick limit).

Geron Corporation has sponsored human clinical trials of several anti-cancer products.

In 2014 Geron exclusively licensed imetelstat to Janssen Biotech.

In addition to testing drug candidates that exploit cancer cell's dependence on telomerase, Geron is researching the possible applications of activating the enzyme in normal cells to delay cellular senescence. The company is in the early stages of developing a telomerase based treatment for HIV called TAT0002, which is the saponin cycloastragenol in Chinese herb Astragalus propinquus. Geron has granted a license to Telomerase Activation Sciences to sell TA-65, the telomerase activator agent also derived from astragalus. In October 2010 Intertek/AAC Labs, an ISO 17025 internationally recognized lab, found the largest component of TA-65 to be Cycloastragenol.

Geron originally investigated telomerase as a means of understanding and modifying human aging. However, Geron has ceased aging research of any kind.

On January 23, 2009, Geron received FDA approval to begin Phase I testing of GRNOPC1 in humans. GRNOPC1 is an embryonic stem cell based drug that is designed to treat specific forms of spinal cord injury through remyelination of damaged axons. This trial does not involve direct use of stem cells however, as GRNOPC1 is composed of oligodendrocyte progenitor cells derived from embryonic stem cell lines. Studies have shown significant restoration of mobility in animals with spinal injuries that received cells.

Geron also has several other embryonic stem cell treatments that are still in the preclinical phase, including GRNCM1, a treatment for heart disease, and GRNIC1, a treatment for diabetes. In tests with diabetic mice, 80% of the mice given GRNIC1 were still alive in 50 days while the entire control group, which was given no treatment, perished.

Geron sold its human stem cell research assets to Asterias in 2013.

As of October 2010 and November 2010, One of Geron's most highly publicized trial therapy products has been GRNOPC1, a stem cell therapy designed to heal severe spinal cord injuries. The cells in the GRNOPC1 therapy have been coaxed into becoming early myelinated glial cells, a type of cell that insulates nerve cells. For every GRNOPC1 cell that is injected in the patient, they become six to 10 cells in a few months. In Oct 2011 updated results on 4 patients were released. The trial was discontinued in Nov 2011.

In early 2013 BioTime, whose CEO is Geron founder Michael D. West, acquired 400 patents and other intellectual property related to embryonic stem cells from Geron and later went on to restart the trial.

Geron Corporation initially held exclusive rights to three cell types derived from embryonic stem cells, as the result of paying for the research originally conducted by Dr. James Thomson at the University of Wisconsin–Madison. The patents on the other three cell types are owned by the Wisconsin Alumni Research Foundation (WARF). WARF and Geron did not charge academics to study human stem cells but did charge commercial users. In 2001 WARF came under public pressure to widen access to human stem-cell technology, and they launched legal action against Geron Corporation to recover some of the previously sold rights. The two sides agreed that Geron would keep the rights to only three cell types.

In October 2006, a legal challenge was mounted to overturn these patents by The Foundation for Taxpayer and Consumer Rights and the non-profit patent-watchdog Public Patent Foundation. They contended that two of the patents granted to WARF are invalid because they cover a technique published in 1992 for which a patent had already been granted to an Australian researcher. Another part of the challenge came from the molecular biologist Jeanne Loring who stated that University of Wisconsin–Madison stem cell pioneer James Thomson's techniques (currently patents held by WARF) are rendered obvious by a 1990 paper and two textbooks. The outcome of this legal challenge was particularly relevant to the Geron Corporation as it can only license patents that are upheld. The patents were ultimately upheld when the reexamination concluded in 2008.

As an interim measure, on January 23, 2007 WARF relaxed the stem cell patents, allowing industry-sponsored research at academic and non-profit institutions without a license. WARF will allow easier and simpler cost free cell transfers among researchers and would not require a license or agreement from California's taxpayer-funded stem cell research program.

As a participant in the then-controversial stem cell and cloning area, Geron Corporation was asked to testify about its technology before the U.S. Congress. In 2001, when Congress was attempting to ban all forms of cloning, then Geron CEO Thomas Okarma spoke before Congress to preserve cloning for therapeutic purposes.