EXHIBIT 10.4

FIRST AMENDMENT TO
EMPLOYMENT
AGREEMENT

     THIS FIRST AMENDMENT (the
“First Amendment”) to the Employment Agreement, including all Exhibits thereto (the
“Employment Agreement”) by and between Andrew J. Grethlein (“Executive”) and Geron
Corporation, a Delaware Corporation (the “Company”) is made effective February
11, 2014. Capitalized terms used in this First Amendment that are not otherwise
defined herein shall have the meanings provided therefor in the Employment
Agreement. 

     WHEREAS, the Employment Agreement was entered by the Company and
Executive effective September 17, 2012; and 

     WHEREAS, the Company and Executive desire to further amend the
Employment Agreement as set forth herein.

     NOW, THEREFORE, in consideration of the mutual promises and covenants
contained herein, it is hereby agreed by and between the parties hereto as
follows: 

AGREEMENT

		1.	Section 3.1 of the Employment Agreement (Base
      Salary) is hereby deleted in its entirety and
      replaced with the following:
	     	       	     	
				
      “3.1 Base Salary. Executive shall
      receive for services to be rendered hereunder such annual base salary as
      is approved by the Board of Directors of the Company (the “Board”) or the
      Compensation Committee of the Board, payable on the regular payroll dates
      of the Company, subject to increase in the sole discretion of the Board or
      Compensation Committee of the Board (the “Base Salary”). As of the
      effective date of this first amendment, Executive’s Base Salary is
      $379,000.” 

				 
		2.	Section
      3.2 of the Employment Agreement (Bonus) is hereby deleted in its entirety and replaced with the
      following:
				 
				
      “3.2 Bonus. Executive shall be
      eligible to earn, for each fiscal year of the Company ending during
      Executive’s employment with the Company, an annual discretionary cash
      bonus (an “Annual Bonus”) targeted at forty-five percent (45%) of
      Executive’s Base Salary. If the Company determines, in its reasonable
      discretion, that Executive has engaged in any misconduct intended to
      affect the payment of his/her Annual Bonus, or has
otherwise engaged in any act or omission that would constitute Cause for
termination of employment, as defined by Section 1.2 of the Agreement, Executive
will automatically and immediately forfeit his/her entire Annual Bonus. If the
Annual Bonus has already been paid to Executive, such Annual Bonus will be
deemed unearned, and the Company shall have the right to recover the entire
amount of the Annual Bonus paid to Executive for the calendar year(s) in which
such misconduct or other act or omission constituting Cause occurred. Without
limiting the foregoing, any such misconduct or other act or omission
constituting Cause will subject Executive to disciplinary action up to and
including termination of employment. In addition, any Annual Bonus paid to
Executive for the calendar year(s) in which such misconduct or other Cause
occurred is subject to recoupment in accordance with The Dodd–Frank Wall Street
Reform and Consumer Protection Act and any implementing regulations, any other
clawback policy adopted by the Company and any compensation recovery policy
otherwise required by applicable laws, regulations or statutes. Recovery by the
Company of an Annual Bonus in accordance with this Section shall not constitute
an event giving rise to a right by Executive to voluntarily terminate his/her
employment for cause based on such recovery by Company, nor shall it constitute
“constructive termination”, or any similar term or circumstance under the
Agreement or any other plan or agreement with the Company.” 



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First Amendment to Employment
Agreement/Grethlein 








Except as expressly set forth herein,
all terms and conditions of the Employment Agreement, as amended by this First
Amendment, remain unchanged and in full force and effect. 

In Witness Whereof, the parties have executed this First Amendment on the respective dates set forth below:



	GERON
      CORPORATION
	 
	By:	/s/ John A.
      Scarlett
		John A. Scarlett, MD
		President & Chief Executive Officer
	 
	Date: 	10 Feb
    14



Accepted and agreed this
11th day of February, 2014. 

	/s/ Andrew Grethlein
	Andrew J.
      Grethlein


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First Amendment to Employment
Agreement/Grethlein