Exhibit 10.13





 


CANCER PREVENTION PHARMACEUTICALS,
INC.


 


AMENDMENT TO INVESTORS’ RIGHTS
AGREEMENT


 


This Amendment to Investors’
Rights Agreement (“Amendment”) is made as of September 27, 2012 by and between Cancer Prevention Pharmaceuticals, Inc.,
a Delaware corporation (the “Company”) and the undersigned Investors. Capitalized terms used but not otherwise defined
herein shall have the meanings assigned to such terms in that certain Investor Rights Agreement dated as of September 17, 2012
between the Company and the Investors (the “Agreement”).


 


WHEREAS, together, the
undersigned Investors and the Company are authorized and desire to amend the Agreement in the manner herein provided.


 


NOW THEREFORE, in consideration
of the mutual covenants, promises and agreements of the Company and the undersigned Investors and other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the parties hereby agree as follows:


 


		1.	Amendment of Agreement. The Company and the undersigned Investors hereby amend the Agreement
in the manner set forth herein. Except as specifically provided herein, the terms of the Agreement shall remain in full force and
effect.



 


		2.	Recitals. Recitals B, C, and D are hereby amended to read as follows:



 


		B.	The Company proposes to sell, or has sold,
shares (“Financing”) of its Series A-2 Convertible Preferred Stock (“Series A-2 Preferred”)
to the purchasers identified on Series A-2 Preferred Stock Purchase Agreement (the “Purchase Agreement”).



 


		C.	The Investors are, or will be, either (i) former Note Holders of the Notes which have been converted
pursuant to the Conversion or (ii) purchasers of Series A-2 Preferred listed on the Purchase Agreement.



 


		D.	As a condition to the Financing and the
Conversion, the Parties have agreed to enter into this Agreement.



 


		3.	Definitions – Section 1.1.



 


		A.	The following definitions are added to Section 1.1 of the Agreement:



  


“Initial Closing”
shall mean the date of the initial sale of shares of the Company’s Series A Preferred Stock under the Purchase Agreement.


 


“Purchase Agreement”
shall have the meaning set forth in the Recitals.


 




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“Series A
Preferred Stock” shall mean the Company’s Series A-1 Convertible Preferred Stock and Series A-2 Convertible
Preferred Stock.


 


		B.	The following definitions are amended to read as follows:



 


“Conversion
Stock” shall mean shares of Common Stock issued upon conversion of the Series A Preferred Stock.


 


“Right of First Refusal
and Co-Sale Agreement” shall mean the agreement of that name of even date herewith by and between the Company, the
holders of Series A Preferred Stock and certain holders of Common Stock.


 


The parties are signing this Amendment to
Investors’ Rights Agreement as of the date stated in the introductory clause.


 


	Cancer Prevention Pharmaceuticals, Inc.	 
	 	 
	By:	/s/ Jeffrey Jacob	 
	 	Jeffrey Jacob, CEO	 


 


	Stockholder	 	Signature	 	Series
    A-1

    Preferred

    Shares Held
	 	 	 	 	 
	Frank and Linda Meyskens	 	/s/
    Frank Meyskens	 	61,045
	 	 	Frank Meyskens	 	 
	 	 	 	 	 
	Eugene and Sandra Gerner	 	/s/
    Eugene Gerner	 	60,963
	 	 	Eugene Gerner	 	 
	 	 	 	 	 
	Jeffrey E. Jacob	 	/s/
    Jeffrey Jacob	 	122,009
	 	 	Jeffrey Jacob	 	 
	 	 	 	 	 
	GDB Investments, LLP	 	/s/
    Daniel Donovan	 	672,643
	 	 	Daniel Donovan	 	 
	 	 	 	 	 
	Translational Accelerator, LLC	 	/s/
    Eric Tooker	 	2,021,853
	 	 	Eric Tooker	 	 


 




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