, DATED MARCH 20, 2014 Geron Reports Myelofibrosis IST Placed on Partial Clinical Hold Patients Deriving Clinical Benefit May Continue Imetelstat Treatment Menlo Park, Calif.

PRESS RELEASE, DATED MARCH 20, 2014

Geron Reports Myelofibrosis IST

Placed on Partial Clinical Hold

Patients Deriving Clinical Benefit

May Continue Imetelstat Treatment

Menlo Park, Calif., March 20,

2014 Geron Corporation (Nasdaq: GERN)

announced today that patients currently enrolled in the investigator-sponsored

clinical trial of imetelstat in myelofibrosis (Myelofibrosis IST) who are

deriving clinical benefit may continue imetelstat treatment under a partial

clinical hold placed by the U.S. Food and Drug Administration (FDA). The

investigator of the Myelofibrosis IST is Dr. Ayalew Tefferi of Mayo Clinic,

Rochester, Minnesota.

The partial clinical hold means that no

new patients may be enrolled into the Myelofibrosis IST, and patients currently

enrolled must demonstrate that they are deriving clinical benefit in order to

continue taking imetelstat. Mayo Clinic informed Geron in January 2014 that the

Myelofibrosis IST had ceased enrolling new patients, and did not cite any safety

concerns as the basis for that decision. The investigator has agreed to provide

to the FDA specific criteria he will use to determine which patients will

continue imetelstat treatment in the Myelofibrosis IST.

In its written notification to the

investigator, the FDA cited the reason for the partial clinical hold was that a

safety signal of hepatotoxicity had been identified in clinical trials of

imetelstat, and that it is not known if this hepatotoxicity is reversible. In

order to resolve the partial clinical hold on the Myelofibrosis IST, the

investigator is required to provide to the FDA follow-up information regarding

reversibility of hepatotoxicity for all patients who received imetelstat in the

Myelofibrosis IST. For patients who did not experience any abnormality in liver

function tests (LFTs), LFT follow-up until 30 days from the last imetelstat dose

must be obtained. For patients who experienced any abnormality in LFTs,

follow-up LFTs must be obtained until resolution to baseline or normal range for

at least two consecutive determinations. Dr. Tefferi has informed Geron that he

plans to work diligently to seek release of the partial clinical hold.

As previously announced, Geron s

Investigational New Drug (IND) application related to imetelstat is currently on

full clinical hold following the FDA s review of data related to safety in the

company s then-ongoing clinical trials. A full clinical hold is an order that

the FDA issues to a trial sponsor to suspend all ongoing clinical trials and

delay all proposed trials under that IND. With the full clinical hold, the company has stopped

imetelstat treatment in a total of ten patients in the Geron-sponsored Phase 2

clinical trials of imetelstat in essential thrombocythemia or polycythemia vera

and in multiple myeloma.

Geron expects to provide an update

regarding its clinical hold during the company s first quarter conference call.

Geron is a clinical stage

biopharmaceutical company developing a first-in-class telomerase inhibitor,

imetelstat, in hematologic myeloid malignancies. For more information about

Geron, visit www.geron.com.