EXHIBIT 10.3

[Geron Letterhead]

Revised Final Offer of
Employment

April 8, 2009

Stephen M. Kelsey, M.D.2327 Greer RoadPalo Alto, CA 94303

Dear Steve:

On behalf of Geron Corporation
("Geron"), I am pleased to extend you a final offer of employment as Executive
Vice President, Chief Medical Officer, Oncology. This is a corporate officer,
regular full-time exempt position, reporting directly to me. You will have
direct responsibility for managing the clinical development of our oncology
portfolio, the basic research programs in oncology and day-to-day operations of
the Oncology Business Unit at Geron. Your initial direct reports will be Melissa
Behrs, Senior Vice President Therapeutic Development, Oncology; Fabio Benedetti,
Senior Vice President Clinical Development, Oncology; Soo-Peang Khor, Vice
President Research, Oncology, and Catherine Howard, Director Clinical
Operations. As you know we are recruiting for a new Head of Clinical Operations
who would report to you, at which time Catherine would report to that new
individual. You will be a member of the Geron Operating Committee - the
strategy-setting body of the Company.

Your annual salary will be $400,000
which will be paid on a semi-monthly basis. In addition, you will be granted
options to purchase two hundred thousand (200,000) shares of Geron common stock
at an exercise price equal to the fair market value of such shares at the date
the options are granted. According to our 2002 Equity Incentive Plan, the
options will be granted on the third Wednesday of the month following your start
date. The vesting schedule is as follows: 12.5% of the options will vest after
your first six months of employment, with the remainder vesting monthly over the
following 42 months. You will be asked to sign a Stock Option Agreement, and the
terms of your options will be governed in all respects by the terms of the Stock
Option Agreement and Equity Incentive Plan.

Should you agree to a start date on or
prior to May 1, 2009, you will be granted 40,000 shares of Geron common stock,
25% vesting after one year of employment, the remainder after your second year.

As a regular full-time employee you are
eligible to participate in the companys medical, dental, vision, life
insurance, and long-term disability insurance programs. You may also sign up to
participate in our 401(k) Retirement Savings Plan and our Employee Stock
Purchase Plan.

You will also be eligible to
participate in the companys incentive bonus program. This is a variable and
discretionary program, generally considered at the end of each year. It is tied
to the achievement of certain performance goals established for the Company and
each individual. The total bonus pool generated for distribution, if any, is
determined at the discretion of the Geron Board of Directors and then
distributed based on individual and company performance. Your maximum potential
bonus is 45% of your base salary. We will agree not to prorate your bonus award
based on your 2009 tenure at Geron.

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As a condition of employment, you must
agree to the terms of and sign the enclosed Proprietary Information and
Inventions Agreement. Please sign page 4 and Exhibit A of the Agreement and
return it with this letter. You will also be obligated to comply with all
company policies and procedures. We will arrange a new-employee orientation for
you shortly after your arrival.

In accordance with Federal Law, all new
employees are required to present evidence of their eligibility to be employed
in the United States. Accordingly, we request that you provide us with a copy of
an appropriate document for this purpose within 72 hours of your employment
date. This may be a birth certificate, a passport, a visa or drivers license
and social security card.

Your employment is at will. You or
the Company may terminate employment at any time with or without cause, with or
without notice. This letter, when signed by you, will constitute the complete
agreement between Geron and you with respect to the duration of your employment
and the initial terms of the position, and supersedes all prior negotiations and
agreements pertaining to the position, whether written or oral. No special or
implied conditions or terms of employment and no amendment to the at-will nature
of your employment will be binding unless made in writing and signed by the CEO
of the Company and you.

If this arrangement is acceptable to
you, please indicate your acceptance by returning a signed copy of this offer
letter and the Proprietary Information and Inventions Agreement to Human
Resources. This final offer of employment will expire on April 15, 2009 unless
accepted prior to that date.

Sincerely,

/s/ Thomas Okarma

Thomas Okarma, Ph.D.,
M.D.President, CEO

Enclosures

AGREED AND ACCEPTED:

|/s/ Stephen Kelsey         |  | 10thApril 2009 | 
|-------------------------- |  | -------------- | 
|Stephen Kelsey,
      M.D. |  | Date           | 

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