Geron Corp. : Updated Results from Geron's Imetelstat Phase 2 Proof-of-Concept Trial in Essential Thrombocythemia Presented at

Geron Corp. : Updated Results from Geron's Imetelstat Phase 2 Proof-of-Concept
   Trial in Essential Thrombocythemia Presented at the European Hematology
                             Association Congress

Data from an Additional Six Months of Imetelstat Treatment and Follow-Up since
                                   ASH 2012

Imetelstat Continues to be Well Tolerated with No New Safety Signals Reported;
  No Patients Have Discontinued Treatment Due to Drug-Related Adverse Events

              Hematologic and Molecular Responses are Maintained

MENLO PARK, Calif., June 16, 2013 - Geron Corporation (Nasdaq: GERN) today
announced that updated clinical results from the company's Phase 2 trial of
imetelstat in essential thrombocytopenia (ET) were presented in an oral
session at the 18^th Congress of the European Hematology Association (EHA) in
Stockholm by a principal investigator of the trial, Prof. Dr. med. Gabriela M.
Baerlocher, of the University Hospital and University of Bern, Switzerland. ET
is a chronic blood disorder that is representative of a group of diseases
known as myeloproliferative neoplasms (MPNs). The initial trial results from
14 patients with ET were presented at the American Society of Hematology (ASH)
annual meeting in December 2012. The updated results, which showed robust
hematologic and molecular responses in patients treated with imetelstat,
included data for an additional six months of treatment and follow-up for the
original 14 patients, as well as data from four additional patients enrolled
in the trial after the data cut-off for the ASH presentation. To view the
presentation slides, please visit

"The observed 100% hematologic response rate in the updated data set,
accompanied by a molecular response rate of 88% among the patients who had a
JAK2 V617F mutation, are consistent with the data reported at ASH last year,"
said Prof. Baerlocher. "Imetelstat continues to be well tolerated in this
trial. With no patients on treatment losing hematologic response, and
molecular responses maintained in 86% of the patients, the drug also appears
to have good durability of its effects on the disease."

TrialRationale and Design
Geron's multi-center, single arm, open-label Phase 2 trial of imetelstat in
patients with ET was designed to provide proof-of-concept for the potential
use of the drug as a treatment for hematologic myeloid malignancies, including
myelofibrosis (MF), myelodysplastic syndromes (MDS) and acute myelogenous
leukemia (AML). The trial leveraged clinical observations from Phase 1; i.e.,
that imetelstat reduces platelet counts, as well as non-clinical observations
that imetelstat distributes well to bone marrow in rodent models and
selectively inhibits the proliferation of malignant progenitors ex vivo from
patients with ET. Published non-clinical data also suggest elevated telomerase
activity in malignant progenitors and shorter telomeres in granulocytes from
patients with MPNs compared to healthy controls.

The primary endpoint of the trial was hematologic response and the secondary
endpoints included molecular response and safety. Hematologic responses were
measured by reductions in platelet counts, which are elevated in patients with
ET. Molecular mutations, such as JAK2 V617F, which occur in 50% of patients
with ET and are believed to be acquired in malignant clonal progenitor cells,
can be used as molecular markers of disease burden. Therefore, molecular
responses were measured by reductions in JAK2 V617F allelic burden compared to
the normal, or wild type, JAK2 gene in circulating granulocytes. A decrease in
the proportion of JAK2 V617F relative to wild type JAK2 is consistent with
selective inhibition of the neoplastic progenitor cells responsible for the
disease. Hematologic and molecular responses were graded using adapted
European LeukemiaNet criteria, as defined by Barosi, et al, in the journal
Blood (2009).

The trial was closed to enrollment in December 2012, with a total of 20
patients enrolled: 18 with ET and two with polycythemia vera (PV). Results for
efficacy were presented from all 18 ET patients enrolled in the trial, with a
median time on imetelstat treatment of 14 months (range 3 months to 2.5
years), as of a May 2013 data cut-off date. At this data cut-off date, there
was insufficient efficacy follow-up data available from the two patients with
PV, but follow-up data for safety were included. The presentation at the ASH
annual meeting in December 2012 reported data as of an October 2012 cut-off
date from the first 14 ET patients, with a median time on imetelstat treatment
of eight months.

Efficacy Results
All 18 ET patients were refractory to, intolerant of or had refused
conventional therapies (hydroxyurea, anagrelide and/or interferon-alpha).
Platelet counts were reduced in all patients (a 100% hematologic response
rate) and normalized in 16 out of 18 patients (an 89% complete response (CR)
rate). The JAK2 V617F gene mutation was detected in eight patients. Seven out
of the eight (88%) patients achieved 72% to 96% reductions in JAK2 V617F
allele burden that qualified as partial molecular responses (PRs) within three
to 12 months of treatment with imetelstat. Molecular PRs were maintained in
six of the seven (86%) patients, with a median follow-up of 9.5 months (range
0 to 19 months) after first achieving a response. The median durations of
hematologic and molecular response have not yet been reached.

Imetelstat was initially administered weekly by intravenous infusion during an
induction phase. After achieving a hematologic CR, which occurred in a median
time of six weeks, a maintenance treatment phase was begun in which dosing
frequency was modified based on a patient's individual response profile. As of
the May 2013 data cut-off date, follow-up data for the maintenance phase were
available for 15 out of 16 patients who attained a hematologic CR. In all 15
patients the frequency with which imetelstat was administered to maintain the
response was reduced to every two weeks or less (up to every seven weeks),
generally decreasing over time. 13 of the 16 patients (81%) who attained a
hematologic CR remain on study as of May 2013, with the median duration of
treatment of 14.5 months. As of May 2013, a total of four ET patients have
discontinued study treatment. The reasons cited for discontinuation include
frequency of imetelstat treatment that was required to maintain a response
(n=1), co-morbid conditions/social issues (n=2) and convenience issues (n=1).

Safety Results
In the trial, long-term administration of imetelstat was generally well
tolerated. There were no new safety signals observed in the six-month update,
and no patients discontinued the trial due to drug-related adverse events. The
majority of the non-hematologic adverse events were mild-to-moderate in
severity, the most frequent assessed as imetelstat-related by investigators
being gastrointestinal events and fatigue. No drug-related Grade 4
non-hematologic adverse events were reported.

Three patients had Grade 4 neutropenia, but no cases of febrile neutropenia
were reported. No thromboembolic events or bleeding events associated with
thrombocytopenia were reported.

At least one abnormal liver function test (LFT) was observed in laboratory
findings in all patients. The majority were Grade 1 elevations in alanine
aminotransferase (ALT) and aspartate aminotransferase (AST); two Grade 3
increases in ALT/AST were reversible on dose reduction. With longer dosing,
Grade 1 increases in alkaline phosphatase were observed, associated with
mostly Grade 1 to some Grade 2 unconjugated hyperbilirubinemia. LFT
abnormalities do not appear to progressively worsen over time. No liver injury
symptoms were reported and no patients discontinued study treatment due to
enzyme elevations.

Further Development of Imetelstat in Hematologic Malignancies
"The molecular responses observed in the ET trial suggest that imetelstat had
a relatively selective inhibition of the malignant progenitor cells, which are
believed to be responsible for the underlying disease," said John A. Scarlett,
M.D., Geron's President and Chief Executive Officer. "As a consequence, we
believe that imetelstat may have potential as a treatment for other
hematologic myeloid malignancies, including myelofibrosis."

Based on data from the trial of imetelstat in patients with ET, in November
2012, Dr. Ayalew Tefferi at Mayo Clinic initiated an investigator-sponsored
trial to evaluate the safety and efficacy of imetelstat in patients with MF
and to determine an appropriate dose and schedule for further evaluation. For
more information about this trial, please refer to Dr. Tefferi has communicated
to Geron that enrollment of the first cohort of 11 patients in the study was
completed at the end of March 2013 and that the pre-specified criteria in the
clinical protocol of at least two responders with a clinical improvement (CI),
partial remission (PR) or complete remission (CR) according to the
International Working Group for Myelofibrosis Research and Treatment (IWG-MRT)
criteria in the first 11 patients was met to enable expanded enrollment. In
the first cohort of 11 patients with MF, imetelstat was administered once
every three weeks. In the second cohort of an additional 11 patients with MF,
imetelstat initially will be administered weekly during a four week induction
phase, followed by a maintenance regimen in which imetelstat is given once
every three weeks. Geron expects data from the investigator-sponsored trial,
if positive, to inform the design of a company-sponsored multi-center trial in

Geron also intends to expand its directed program of investigator-sponsored
trials in 2013 to other hematologic myeloid indications, including AML and

About Imetelstat

Imetelstat (GRN163L) is a potent and specific inhibitor of telomerase. This
first-in-class compound is a specially designed and modified short
oligonucleotide, which targets and binds directly with high affinity to the
active site of telomerase. Unique and proprietary oligonucleotide chemistry
improves binding affinity and stability in plasma and tissues. A lipid
modification enables cellular and tissue penetration and biodistribution.

About Geron

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

Use of Forward-Looking Statements

Except for the historical information contained herein, this press release
contains 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 Geron's plans or
expectations for or of: (a) the receipt of or dates to obtain or present data
or other results from any clinical trials, including the
investigator-sponsored trial in myelofibrosis; and (b) clinical development
plans or success of imetelstat, including imetelstat possibly having
applicability for the treatment of any other hematologic myeloid malignancies,
including myelofibrosis, constitute forward-looking statements. These
statements involve risks and uncertainties that can cause actual results to
differ materially from those in such forward-looking statements. These risks
and uncertainties, include, without limitation: (a) regarding the receipt of
or dates for the availability of data or other results - delays in enrollment,
delays caused by institutional review boards or regulatory agencies, shortage
of supply, dependence on clinical trial collaborators and safety issues; and
(b) regarding clinical development plans or success of imetelstat, including
imetelstat possibly having applicability for the treatment of other
hematologic myeloid malignancies, including myelofibrosis and positive safety
and efficacy data from the investigator-sponsored trial in myelofibrosis and
other clinical trials, including the ET clinical trial - those risks and
uncertainties inherent in the development of potential therapeutic products,
including without limitation, results from the ET trial may not mean that
imetelstat has applicability for the treatment of any other hematologic
myeloid malignancies, including myelofibrosis, technical and scientific
challenges, limitations on freedom to operate arising from intellectual
property of others and the protection of Geron's intellectual property rights.
Additional information on the above risks and uncertainties (a) and (b) and
other risks, uncertainties and factors that could cause actual results to
differ materially from those in the forward-looking statements are contained
in Geron's periodic reports filed with the Securities and Exchange Commission
under the heading "Risk Factors," including Geron's quarterly report on Form
10-Q for the quarter ended March 31, 2013. Undue reliance should not be placed
on forward-looking statements, which speak only as of the date they are made,
and the facts and assumptions underlying the forward-looking statements may
change. Except as required by law, Geron disclaims any obligation to update
these forward-looking statements to reflect future information, events or


Anna Krassowska, Ph.D.
Investor and Media Relations



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