Exhibit 10.4

2012 AMENDMENT TO EXCLUSIVE LICENSE AGREEMENT
BETWEEN ENTERON PHARMACEUTICALS, INC.
AND DR. GEORGE B. MCDONALD

This 2012 Amendment (“2012 AMENDMENT”) is made as of the 21st day of December,
2012 by and between ENTERON Pharmaceuticals, Inc., a Delaware corporation
(“ENTERON”), wholly owned subsidiary of SOLIGENIX, INC. (“SOLIGENIX”), and
George B. McDonald, MD (“MCDONALD”).

RECITALS

A.          ENTERON and MCDONALD have entered into an Exclusive License
Agreement dated November 24, 1998, as amended by amendments dated March 5, 2001,
November 20, 2001, December 13, 2005, February 11, 2009, September 15, 2009 and
July 26, 2011 (as amended, the “LICENSE AGREEMENT”).

B.           ENTERON and MCDONALD wish to amend further the LICENSE AGREEMENT as
hereinafter provided.

NOW, THEREFORE, in consideration of the promises and mutual covenants contained
herein, and intending to be legally bound thereby, the parties agree as follows:

1.           Section 3(C)(i) of the LICENSE AGREEMENT is hereby amended by
replacing existing Section 3(C)(i) with the following new Section 3(C)(i) to
read as follows:

“(i) If LICENSEE does have to conduct Clinical Trials to obtain FDA approval of
the first LICENSEE-sponsored NDA for Licensed Product, then LICENSEE shall pay
to LICENSOR within forty-five (45) days of the end of each Calendar Quarter an
amount equal to ten percent (10%) of:  (a) any non-recurring sublicense fees
(including, but not limited to, signing, up-front, and lump-sum fees) and annual
license maintenance fees, if any, received from any Affiliate or Third Party for
the right to practice the Licensed Process(es) or make, use, sell, or import
Licensed Product(s); and (b) all royalties received by LICENSEE from the sale of
Licensed Product(s) by any sublicensed Third Party.”

2.           Section 3(C)(iii) of the LICENSE AGREEMENT is hereby amended by
replacing existing Section 3(C)(iii) with the following new Section 3(C)(iii) to
read as follows:

“(iii) If LICENSEE does have to conduct Clinical Trials to obtain FDA approval
of the first LICENSEE-sponsored NDA for Licensed Product, then LICENSEE shall
pay LICENSOR within forty-five (45) days from the end of each Calendar Quarter
three percent (3%) of all Net Sales of Licensed Products by LICENSEE or a
sublicensed Affiliate.”

3.           ENTERON agrees to pay/reimburse MCDONALD for legal fees for the
preparation, review and execution of this 2012 AMENDMENT and related documents.
 
 
 

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4.           Except as expressly set forth in this 2012 AMENDMENT, the LICENSE
AGREEMENT remains in full force and effect in accordance with its terms.
References in the LICENSE AGREEMENT to the “Agreement” are hereby amended to
refer to the LICENSE AGREEMENT, as amended by this 2012 AMENDMENT. This 2012
AMENDMENT constitutes and contains the entire agreement between the parties with
respect to the subject matter hereof and thereof, and supersedes any prior oral
or written agreements.  This 2012 AMENDMENT will be construed in accordance with
and governed by the laws of the State of New York without regard to principles
of conflicts of law.

IN WITNESS WHEREOF, the parties have executed this 2012 AMENDMENT as of the date
first written above.

ENTERON PHARMACEUTICALS, INC.
 
George B. McDonald, MD
           
By:
/s/ Christopher J. Schaber
 
/s/ George B. McDonald
 
Name:
Christopher J. Schaber, PhD
 
Name: George B. McDonald, MD
 
Title:
Chief Executive Officer
     
 
SOLIGENIX, INC.
         
By:
/s/ Christopher J. Schaber
   
Name:
Christopher J. Schaber, PhD
   
Title:
Chief Executive Officer
   

 
 
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