SOLIGENIX, INC. (Form: 8-K, Received: 07/28/2011 16:52:57)

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Pursuant to Section 13 or 15(d) of

The Securities Exchange Act of 1934

Date of Report (Date of Earliest Event Reported): July 26, 2011

Commission File No. 000-16929

(Exact name of small business issuer as specified in its charter)

DELAWARE			41-1505029
(State or other jurisdiction of incorporation or organization)			(I.R.S. Employer Identification Number)

29 Emmons Drive, Suite C-10 Princeton, NJ			08540
(Address of principal executive offices)			(Zip Code)
(609) 538-8200
(Issuer’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 1.01 Entry into a Material Definitive Agreement.

On July 26, 2011, Soligenix, Inc. (the “Company”), Enteron Pharmaceuticals, Inc., a wholly-owned subsidiary of the Company (“Enteron”), and Sigma-Tau Pharmaceuticals, Inc. (“Sigma-Tau”) entered into an amendment (the “Sigma-Tau Amendment”) to the Collaboration and Supply Agreement dated as of February 11, 2009 (the “Sigma-Tau Agreement”). In exchange for the payment of $5 million by Sigma-Tau to the Company, the Company granted Sigma-Tau an exclusive license to commercialize orBec ® in the “European Territory,” as amended by the Sigma-Tau Amendment. The Sigma-Tau Amendment requires Sigma-Tau to make additional payments to the Company in the aggregate amount of $11 million upon the achievement of milestones. Total milestone payments due from Sigma-Tau under the Sigma-Tau Agreement, including the Sigma-Tau Amendment, could reach up to $26 million (including $1 million paid by Sigma-Tau in September 2009 and the initial $5 million payment under the Sigma-Tau Amendment). The next milestone payments, totaling $2 million, will be made upon notification by the U.S. Food and Drug Administration and the European Medicines Agency of the successful completion of the confirmatory Phase 3 clinical trial of orBec ® for the treatment of acute gastrointestinal Graft-versus-Host disease (“GI GVHD”). The Sigma-Tau Amendment also requires Sigma-Tau to pay the Company a 40% royalty on net sales in the European Territory. Sigma-Tau will also cover all commercialization expenses, including launch activities.

None of the other terms of the Sigma-Tau Agreement were modified in any material respect.

Also on July 26, 2011, the Company, Enteron, and George B. McDonald, MD (“Dr. McDonald”) entered into an amendment (the “License Agreement Amendment”) to the Exclusive License Agreement dated November 24, 1998, as amended (the “License Agreement”). Under the License Agreement, Dr. McDonald would have been entitled to receive (i) $1,250,000 upon the closing of the Sigma-Tau Amendment; and (ii) $250,000 upon an approval of oral beclomethasone dipropionate by the European Medicines Agency. Pursuant to the License Agreement Amendment, the Company will pay Dr. McDonald (i) $612,500 in cash and $400,000 in common stock of the Company (based upon the closing price of the Company’s common stock on July 26, 2011) upon the closing of the Sigma-Tau Amendment and (ii) $400,000 in cash upon an approval of oral beclomethasone dipropionate by the European Medicines Agency.

None of the other terms of the License Agreement were modified in any material respect.

The foregoing descriptions of the Sigma-Tau Amendment and the License Agreement Amendment do not purport to be complete and are qualified in their entirety by reference to the Sigma-Tau Amendment and the License Agreement Amendment, which are attached hereto as Exhibits 10.1 and 10.2, respectively, and incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits.

Exhibit No.		Description

10.1		Amendment to the Collaboration and Supply Agreement between Soligenix, Inc., Enteron Pharmaceuticals, Inc. and Sigma-Tau Pharmaceuticals, Inc. dated as of July 26, 2011. †

10.2		2011 Amendment to Exclusive License Agreement between Enteron Pharmaceuticals, Inc. and Dr. George B. McDonald dated as of July 26, 2011, between Soligenix, Inc., Enteron Pharmaceuticals, Inc. and Dr. George B. McDonald.

99.1		Press release issued by Soligenix, Inc. on July 28, 2011.

† Portions of this exhibit have been omitted pursuant to a request for confidential treatment.

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	Soligenix, Inc.

July 28, 2011	By:	/s/ Christopher J. Schaber
		Christopher J. Schaber, Ph.D.
		President and Chief Executive Officer
		(Principal Executive Officer)

Exhibit 10.1

Portions of this Exhibit have been omitted

pursuant to a request for confidential treatment.

The omitted portions are marked by ***** and have

been filed separately with the Commission.

AMENDMENT TO THE COLLABORATION AND SUPPLY AGREEMENT

BETWEEN SOLIGENIX, INC., ENTERON PHARMACEUTICALS, INC. AND SIGMA-TAU PHARMACEUTICALS, INC.

This amendment (the "Amendment") is entered into effective as of the 26 th day of July, 2011 (the “Amendment Effective Date”) by and between, on the one hand, Soligenix, Inc. (formerly known as DOR BioPharma, Inc.), a Delaware corporation (“SOLIGENIX”), Enteron Pharmaceuticals, Inc., a Delaware corporation a wholly-owned subsidiary of Soligenix (“Enteron”, and together with Soligenix, the “Company”) and on the other hand, Sigma-Tau Pharmaceuticals, Inc. (“Sigma-Tau”).

WHEREAS, Sigma-Tau and Company entered into an agreement titled Collaboration and Supply Agreement dated as of February 11, 2009 (the "Agreement"). The parties now wish to amend the Agreement as set forth herein;

WHEREAS, Sigma-Tau and the Company entered into a Waiver of Right of First Negotiation dated January 18, 2011, where Sigma-Tau waived its right of first negotiation under Section 2.2 of the Agreement to extend its exclusive appointment and related sublicense under Section 2.1 of the Agreement to the EUROPEAN TERRITORY (as defined in the Agreement); and

WHEREAS, Sigma-Tau made an independent bid to Company (outside the scope of Section 2.2 of the Agreement) for such appointment and sublicense to the EUROPEAN TERRITORY, and Company has duly accepted such bid;

NOW, THEREFORE, in consideration of the mutual promises of the parties contained in this Amendment, and for other good and valuable consideration, the parties agree as follows:

1. All capitalized terms not defined herein shall have the meanings described to them in the Agreement.

2. Section 1.5 is deleted in its entirety and amended to read as follows:

“ APPROVAL ” or “ APPROVED ” means all necessary approval granted by the appropriate AGENCY for any country in the TERRITORY for the manufacture, sale, and distribution of the PRODUCT and AG PRODUCT

(The information below marked by ***** has been omitted pursuant to a request for confidential treatment. The omitted portion has been filed separately with the Commission.)

for an indication(s), which may include the FDA for the U.S. and the European Medicines Agency for the European Union.

3. Section 1.21 is hereby amended by inserting the following after the words “the European Union”:

“(to the extent that rights to the PRODUCT are not already sublicensed or licensed by SOLIGENIX or its AFFILIATES in such entrant country)”

4. Section 1.57 is deleted in its entirety and amended to read as follows:

" TERRITORY " means the United States of America (including its territories and possession, as well as Puerto Rico), Canada and Mexico, as well as the EUROPEAN TERRITORY.

5. Section 2.2 is hereby deleted.

6. Section 9.1 is deleted in its entirety and amended to read as follows:

9.1.1 STPI and COMPANY agree that the following milestone has been paid and is no longer due and owing to SOLIGENIX: one million U.S. Dollars (U.S.$1,000,000) to be paid within thirty (30) days of receipt of a report, certified by SOLIGENIX, stating that the first patient in the PHASE 3 TRIAL has been administered the PRODUCT;

STPI shall pay to SOLIGENIX the following amounts plus VAT, if applicable:

9.1.2 one million U.S. Dollars (U.S.$1,000,000) to be paid within thirty (30) days of receipt of a report from SOLIGENIX showing that the PHASE 3 TRIAL has successfully achieved its primary endpoint consistent with the FDA's Special Protocol Assessment (SPA) feedback in support of an NDA;

9.1.3 one million U.S. Dollars (U.S.$1,000,000) to be paid within thirty (30) days of receipt of a report from SOLIGENIX showing that the PHASE 3 TRIAL has successfully achieved its primary endpoint consistent with the European Medicines Agency's Protocol Assistance feedback in support of an MAA;

9.1.3 ***** to be paid within thirty (30) days upon the cumulative NET SALES in the United States of America (including its territories and

(The information below marked by ***** has been omitted pursuant to a request for confidential treatment. The omitted portion has been filed separately with the Commission.)

possession, as well as Puerto Rico), Canada and Mexico , having achieved twenty five million U.S. Dollars (U.S.$ 25,000,000);

9.1.4 ***** to be paid within thirty (30) days upon the NET SALES in the United States of America (including its territories and possession, as well as Puerto Rico), Canada and Mexico , for a consecutive twelve (12) month period exceeding fifty million U.S. Dollars (U.S.$50,000,000);

9.1.5 five million U.S. Dollars (U.S.$5,000,000) to be paid within ten (10) days of the execution of the Amendment dated July 26, 2011 extending STPI’s exclusive appointment and related sublicense under Section 2.1 of the Agreement to the EUROPEAN TERRITORY;

9.1.6 ***** to be paid within thirty (30) days of receipt of a report from SOLIGENIX showing that SOLIGENIX has obtained APPROVAL for PRODUCT from the European Medicines Agency;

9.1.7 ***** to be paid within thirty (30) days upon the cumulative NET SALES in EUROPEAN TERRITORY, having achieved twenty million Euros (€20,000,000); and

9.1.8 ***** to be paid within thirty (30) days upon the NET SALES in the EUROPEAN TERRITORY, for a consecutive twelve (12) month period exceeding forty million Euros (€40,000,000).

For the avoidance of doubt, each of the above milestones will be payable only once for each event described.

The above milestone payments are to be considered STPI's contribution to and reimbursement of the costs and expenses related to the PHASE 3 TRIAL and other activities necessary to obtain and maintain the MARKETING AUTHORIZATIONS. Accordingly, SOLIGENIX undertakes to utilize such milestones payments received prior to the granting of the MARKETING AUTHORIZATIONS only for the furtherance of the PHASE 3 TRIAL and other PRODUCT development activities necessary to obtain and maintain the MARKETING AUTHORIZATIONS in the TERRITORY or relevant subdivision thereof; SOLIGENIX shall send to STPI quarterly reports showing the proper allocation of the above milestones payments.

1. The attached Appendix B-1 shall be added to, and incorporated into, Appendix B of the Agreement.

2. Appendix C of the Agreement is deleted in its entirety and replaced with the new Appendix C, dated July 26, 2011, attached hereto.

3. In addition to and without limiting any other rights set forth in the Agreement and subject to the last sentence in this section 8, in the event that neither STPI, nor its distributors, nor STPI’s AFFILIATES, have had a first commercial sale of the PRODUCT (which shall mean a sale or transfer for value, not including providing free PRODUCT for clinical trial purposes) by the second (2 nd ) anniversary of SOLIGENIX obtaining APPROVAL for PRODUCT from the European Medicines Agency in at least one (1) of the following countries of the EUROPEAN TERRITORY: the United Kingdom, France, Spain, Italy or Germany (the “Major Market”), then provided that the PRODUCT has been timely supplied by SOLIGENIX in accordance with the terms of the Agreement, SOLIGENIX shall have the right to terminate this Amendment (including, without limitation, the rights to COMMERCIALIZE the PRODUCT in the EUROPEAN TERRITORY as provided hereunder) upon ninety (90) days’ prior written notice to STPI. Upon STPI satisfying the conditions in the clause above, SOLIGENIX shall have no further rights under this Section 8 of this Amendment only, but shall continue to retain all other rights under the Agreement as amended by this Amendment. Upon such a termination, STPI’s rights under the previous terms and conditions of the Agreement, prior to the execution of this Amendment, shall remain in full force and effect, as if this Amendment had never been in effect. SOLIGENIX’s termination right under this Section 8 shall not apply if the first commercial sale of the PRODUCT in the European Territory becomes commercially unreasonable or impracticable due to an existing Generic Product in the Major Market, regulatory activity by an AGENCY which either changes the label from the initially approved label or issues a warning with respect to the class of drugs in which the Product is classified, and which would have a material and adverse effect on the Product, unfavorable final reimbursement or pricing on the PRODUCT by a government which would have a material and adverse effect on the COMMERCIALIZATION of the PRODUCT, legal activity within a country of the EUROPEAN TERRITORY which prohibits the sale of the Product, or has a material and adverse effect on the manufacture or sale of the PRODUCT, or a serious adverse drug reaction occurs with the PRODUCT, the intensity or frequency of which materially exceeds that known for equivalent products, in each case so long as the foregoing were not under STPI’s control.

Accepted and Agreed:

Soligenix, Inc.

By /s/ Christopher J. Schaber

Name Christopher J. Schaber

Title President and CEO

Date July 26, 2011

Sigma-Tau Pharmaceuticals, Inc.

By /s/ Gregg Lapointe

Name Gregg Lapointe

Title CEO

Date July 26, 2011

Enteron Pharmaceuticals, Inc.

By /s/ Christopher J. Schaber

Name Christopher J. Schaber

Title President and CEO

Date July 26, 2011

Appendix B-1

EUROPEAN PATENT RIGHTS

LKF Ref. No.	Title	Serial No.	Filing Date	Status	Patent No.
50 2.206CH	METHOD OF TREATING INFLAMMATORY DISORDERS OF THE GASTROINTESTINAL TRACT USING TOPICAL ACTIVE CORTICOSTEROIDS	02723424.4	15-Oct-2003	Granted	1392321
502.206DE		02723424.4	15-Oct-2003	Granted	1392321
502.206DK		02723424.4	15-Oct-2003	Published
502.206EP		02723424.4	15-Oct-2003	Granted	1392321
502.206FR		02723424.4	15-Oct-2003	Published
502.206GB		02723424.4	15-Oct-2003	Granted	1392321
502.206IE		02723424.4	15-Oct-2003	Granted	1392321
502.206LU		02723424.4	15-Oct-2003	Granted	1392321
502.206MC		02723424.4	15-Oct-2003	Granted	1392321
502.206NL		02723424.4	15-Oct-2003	Granted	1392321
502.206SE		02723424.4	15-Oct-2003	Granted	1392321
502.208CH	Treatment of Graft-Versus-Host Disease and Leukemia with BDP	05856121.8	22-Jun-2007	Published
502.208DE		05856121.8	22-Jun-2007	Granted	602005023655.4-08
502.208DK		05856121.8	22-Jun-2007	Published
502.208EP		05856121.8	22-Jun-2007	Granted	1830857
502.208FR		05856121.8	22-Jun-2007	Published
502.208GB		05856121.8	22-Jun-2007	Published
502.208IE		05856121.8	22-Jun-2007	Granted	1830857
502.208LU		05856121.8	22-Jun-2007	Published
502.208MC		05856121.8	22-Jun-2007	Granted	1830857
502.208NL		05856121.8	22-Jun-2007	Published
502.208SE		05856121.8	22-Jun-2007	Published

(The information below marked by ***** has been omitted pursuant to a request for confidential treatment. The omitted portion has been filed separately with the Commission.)

Appendix C

July 26, 2011

SUPPLY PRICE

With respect to the United States of America (including its territories and possession, as well as Puerto Rico), Canada and Mexico:

SOLIGENIX shall sell and deliver to STPI the PRODUCT and AG PRODUCT at a SUPPLY PRICE equal to thirty-five percent (35%) of the NET SALES of the PRODUCT and AG PRODUCT. For the sake of good order, SOLIGENIX declares that such thirty-five percent (35%) SUPPLY PRICE is to be allocated as follows:

(i)	FULLY BURDENED MANUFACTURING COST as a transfer price for the PRODUCT and AG PRODUCT, to be paid within thirty (30) days of receipt of the relevant invoice (the "FIXED COMPONENT"); and

(ii)	The remaining amount (representing the remainder of the purchase price for the PRODUCT) to be paid within thirty (30) days of the end of each calendar quarter (the "PERCENTAGE COMPONENT").

With respect to the EUROPEAN TERRITORY:

SOLIGENIX shall sell and deliver to STPI the PRODUCT and AG PRODUCT at a SUPPLY PRICE equal to forty percent (40%) of the NET SALES of the PRODUCT and AG PRODUCT. For the sake of good order, SOLIGENIX declares that such forty percent (40%) SUPPLY PRICE is to be allocated as follows:

(i)	FULLY BURDENED MANUFACTURING COST as a transfer price for the PRODUCT and AG PRODUCT, to be paid within thirty (30) days of receipt of the relevant invoice (the "FIXED COMPONENT"); and

(ii)	The remaining amount (representing the remainder of the purchase price for the PRODUCT) to be paid within thirty (30) days of the end of each calendar quarter (the "PERCENTAGE COMPONENT").

STPI agrees that, while it has the discretion to set the pricing for the PRODUCT and AG PRODUCT, the SUPPLY PRICE shall in no event be less than ***** of the FIXED COMPONENT.

For the avoidance of doubt, in no case shall the SUPPLY PRICE (i.e., the FIXED COMPONENT plus the PERCENTAGE COMPONENT) exceed forty percent (40%) of the NET SALES of the PRODUCT in the EUROPEAN TERRITORY, or thirty-five percent (35%) of the NET SALES of the PRODUCT in the United States of America (including its territories and possession, as well as Puerto Rico), Canada and Mexico .

Notwithstanding the foregoing, but subject to Article 9.3, upon the expiration of the last to expire VALID CLAIM covering the PATENT RIGHTS, the SUPPLY PRICE shall be reduced to a percentage of NET SALES of the PRODUCT or AG PRODUCT to be mutually agreed upon by the parties. If the parties are unable to agree, either party may, by written notice to the other party, have such dispute referred to the respective officers designated below, or their successors, for attempted resolution by good faith negotiation within thirty (30) days after such notice is received. Such designated officers are as follows:

For SOLIGENIX: Christopher J. Schaber, Ph.D., President and CEO

For STPI: Gregg Lapointe, Chief Executive Officer

In the event that the designated officers are not able to resolve the dispute within such thirty (30)-day period, or such other period of time as the parties may mutually agree to in writing, the dispute shall be referred to and finally and exclusively resolved as follows:

(i)

Each party shall appoint an independent expert with reasonably significant and demonstrable experience in the pharmaceutical industry. Such appointees shall reasonably collaborate and appoint an independent expert who they reasonably believe is capable of determining the amount of the reduction in SUPPLY PRICE (such person, the "ARBITRATOR").

(ii)

The ARBITRATOR shall be instructed to deliver a decision in respect of the foregoing reduction amount that is not above or below each of the parties' last best offer and that otherwise takes into consideration applicable legal, regulatory, commercialization and customary marketing concerns related to the PRODUCT and AG PRODUCT. The ARBITRATOR shall be instructed that its decision with respect to the reduction shall be delivered in ten (10) business days (or such time as the parties may mutually agree or the ARBITRATOR may reasonably request), in writing and shall include a statement describing in reasonable detail the decision of the ARBITRATOR. The decision of the ARBITRATOR shall be final and binding and conclusive upon the parties for all purposes under this AGREEMENT (absent fraud or manifest bad faith by the ARBITRATOR). The fees and expenses of the ARBITRATOR shall be shared equally by the parties.

The remainder of this pag e is intentionally blank.

2011 AMENDMENT TO EXCLUSIVE LICENSE AGREEMENT

BETWEEN ENTERON PHARMACEUTICALS, INC.

AND DR. GEORGE B. MCDONALD

This 2011 Amendment (“2011 AMENDMENT”) is made as of the 26 th day of July, 2011 (the “EFFECTIVE DATE”) by and between ENTERON Pharmaceuticals, Inc., a Delaware corporation (“ENTERON”), wholly owned subsidiary of SOLIGENIX, INC. (“SOLIGENIX”), and George B. McDonald, MD (“MCDONALD”).

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 and September 15, 2009 (as amended, the “LICENSE AGREEMENT”).

B. ENTERON, SOLIGENIX and Sigma-Tau Pharmaceuticals, Inc. (“STPI”) have entered into that certain Amendment to the Collaboration and Supply Agreement dated July 26, 2011 (the “AMENDMENT”), amending the Collaboration and Supply Agreement between ENTERON, SOLIGENIX and STPI dated as of February 11, 2009 (as amended by the AMENDMENT, the “SUPPLY AGREEMENT”), which, among other things, expands the definition of the “Territory” therein to include the European Territory as defined in the SUPPLY AGREEMENT.

C. In connection with the execution of the AMENDMENT, 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. Pursuant to Section 9.1.5 of the SUPPLY AGREEMENT, SOLIGENIX is to receive a non-recurring fee in the amount of Five Million Dollars ($5,000,000) within ten (10) days of the execution of such AMENDMENT (the “EU EXECUTION PAYMENT”). Notwithstanding Section 3(C) of the LICENSE AGREEMENT (including, without limitation, Sections 3(C)(i) and (ii)) and in lieu and replacement of any and all payments owed thereunder with respect to the EU EXECUTION PAYMENT, SOLIGENIX shall: (i) pay to MCDONALD an amount equal to Six Hundred Twelve Thousand Five Hundred Dollars ($612,500) in immediately available funds within ten (10) days after its receipt of the EU EXECUTION PAYMENT; (ii) issue to MCDONALD within ten (10) days after its receipt of the EU EXECUTION PAYMENT a number of shares of Common Stock of SOLIGENIX (“COMMON STOCK”) equal to Four Hundred Thousand Dollars ($400,000) divided by the closing price of the COMMON STOCK on the date of the AMENDMENT as reported by the OTC Bulletin Board, with any fractional shares rounded down to the nearest whole share; and (iii) pay to MCDONALD Four Hundred Thousand Dollars ($400,000) in immediately available funds within five (5) days after the date SOLIGENIX obtains APPROVAL (as defined in the SUPPLY AGREEMENT”) for PRODUCT (as defined in the SUPPLY AGREEMENT”) from the European Medicines Agency or any successor agency thereto.

2. Section 3(C)(viii) of the License Agreement is hereby amended by deleting existing Section 3(C)(viii) and replacing it with new Section 3(C)(viii) to read as follows:

“(viii) Reference is made to that certain Collaboration and Supply Agreement (including without limitation any amendments thereto, “Supply Agreement”) made and entered into as of February 11, 2009, by and between SOLIGENIX, Inc. (“SOLIGENIX”) (formerly known as DOR BioPharma, Inc.) and Sigma-Tau Pharmaceuticals, Inc. (“STPI”). Notwithstanding (i) and (ii) above and in lieu thereof and for so long as the Supply Agreement is in effect, with respect to non-recurring fees payable by STPI pursuant to the Supply Agreement (including but not limited to milestone payments) with respect to the United States of America (including its territories and possession, as well as Puerto Rico), Canada and Mexico, SOLIGENIX shall pay to LICENSOR within forty-five (45) days of the end of each Calendar Quarter an amount equal to ten percent (10%) of such non-recurring fees paid to SOLIGENIX or any Affiliate for such Calendar Quarter; provided that, payment to LICENSOR arising from the milestone payment due as a result of STPI’s receipt of a report, certified by SOLIGENIX, stating that the first patient in the PHASE 3 TRIAL (as defined in the Supply Agreement) in the United States of America has been administered the PRODUCT (as defined in the Supply Agreement) shall be deferred until such time as payment is due to LICENSOR arising from the milestone payment due as a result of STPI’s receipt of a report from SOLIGENIX showing that the PHASE 3 TRIAL for the United States of America has successfully achieved its primary endpoint consistent with the FDA’s Special Protocol Assessment feedback in support of a New Drug Application. SOLIGENIX shall not agree to any amendment to the Supply Agreement that affects or could affect the payment of non-recurring fees to SOLIGENIX thereunder without the prior written consent of LICENSOR.

3. Section 3(C)(ix) of the License Agreement is hereby amended by replacing existing Section 3(C)(ix) with the following new Section 3(C)(ix) to read as follows:

“(ix) Notwithstanding (iii) and (iv) above and in lieu thereof, and for so long as the Supply Agreement is in effect, with respect to sales of PRODUCTS and AG PRODUCTS in the FIELD in the United States of America (including its territories and possession, as well as Puerto Rico), Canada and Mexico, pursuant to the Supply Agreement, SOLIGENIX shall pay to LICENSOR within forty-five (45) days of the end of each Calendar Quarter an amount equal to three percent (3%) of the Net Sales of the PRODUCTS and AG Products (as Net Sales is determined under the Supply Agreement) paid to SOLIGENIX or any Affiliate with respect to such Calendar Quarter (capitalized terms in this sentence other than LICENSOR, Supply Agreement and Calendar Quarter having the meanings given to them in the Supply Agreement). SOLIGENIX shall not agree to any amendment to the Supply Agreement that affects or could affect the amount or calculation of payments to LICENSOR hereunder without the prior written consent of LICENSOR.”

4. MCDONALD hereby consents and agrees to the AMENDMENT.

5. Except as expressly set forth in this 2011 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 2011 AMENDMENT. This 2011 AMENDMENT constitutes and contains the entire agreement between the parties with respect to the subject matter hereof and supersedes any prior oral or written agreements. This 2011 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 2011 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

Soligenix Announces Expansion of Partnership with Sigma-Tau Pharmaceuticals for orBec ® in Europe

Soligenix to Receive up to $16 Million, including Upfront Payment of $5 Million along with 40% Royalty on Net Sales in Europe

Princeton, NJ – July 28, 2011 – Soligenix, Inc. (Soligenix or the Company) (OTC BB: SNGX), a late-stage biopharmaceutical company, announces the expansion and amendment of its North American licensing partnership with Sigma - Tau Pharmaceuticals, Inc. (Sigma - Tau) for the development and commercialization of orBec ® (oral beclomethasone dipropionate or Oral BDP) into the European territory.

As part of the amended agreement, Sigma - Tau has made a $5 million upfront payment to Soligenix. In addition, Sigma - Tau will make additional payments to Soligenix totaling $11 million, subject to the achievement of certain milestones. The first milestone, a $2 million payment, will be made upon the successful completion of the confirmatory Phase 3 clinical trial of orBec ® for the treatment of acute gastrointestinal Graft - versus - Host disease (GI GVHD). Sigma - Tau will also pay Soligenix a 40% royalty on net sales pursuant to which Soligenix will supply the drug product while maintaining worldwide manufacturing rights. All commercialization expense in the European territory, including launch activities, will be borne by Sigma-Tau.

Ugo DiFrancecso, Chief Executive Officer of the Sigma-Tau Group which is headquartered in Rome, Italy, commented, “We are pleased to expand our partnership with Soligenix around orBec ® . We remain optimistic about a near-term approval in the European market and the opportunity to bring our considerable expertise in the distribution of rare disease medicines to ensure that all GI GVHD patients throughout Europe will be able to access this important medicine.”

“We expect the expanded Sigma-Tau collaboration will help us realize the full potential of orBec ® and oral BDP in the treatment of GI GVHD and other inflammatory GI diseases,” stated Christopher J. Schaber, PhD, President and CEO of Soligenix. “We now have an experienced commercialization partner in the second major world market and we are pleased with the robust royalty rates that we have garnered through this strong business relationship. There will also be significant economies of scale that we will realize through having one partner in both major territories. This partnership will provide for the launch and commercialization of orBec ® in North America and Europe, without any further related expense to Soligenix or its shareholders. It also provides us with the potential for ongoing development funding across multiple indications for orBec ® and oral BDP.”

orBec ® , oral beclomethasone dipropionate (oral BDP), is currently the subject of a confirmatory Phase 3 clinical trial in the treatment of acute GI GVHD. This Phase 3 trial, also referred to as the SUPPORTS protocol ( S paring U nnecessary P rednisone P hase 3 o rBec ® R andomized T reatment S tudy), will enroll an estimated 166 patients to confirm the clinically meaningful endpoints observed in previous Phase 2 and Phase 3 clinical studies. The primary endpoint is the treatment failure rate at Study Day 80. This endpoint was successfully measured as a secondary endpoint (p-value 0.005) in the Company’s previous Phase 3 study as a key measure of durability following a 50-day course of treatment with orBec ® (i.e., 30 days following cessation of treatment). The SUPPORTS trial is being conducted at major transplant centers throughout the US, Europe, and Australia and is expected to complete in the second half of 2011. The trial is the subject of a Special Protocol Assessment (SPA) agreement that the Company reached with the US Food and Drug Administration (FDA).

orBec ® was the subject of two prior randomized, double-blind, placebo-controlled clinical trials in acute GI GVHD. The first study was a 60-patient Phase 2 single-center clinical trial conducted at the Fred Hutchinson Cancer Research Center, which demonstrated statistical significance in its primary endpoint of controlling GI GVHD (p-value 0.02). The second study was a 129-patient pivotal Phase 3 multi-center clinical trial conducted at 16 leading bone marrow/stem cell transplant centers in the US and France. Although orBec ® did not achieve statistical significance in the primary endpoint of its pivotal trial, namely median time-to-treatment failure through Day 50 (p-value 0.1177), orBec ® did achieve statistical significance in other key secondary endpoints such as the proportion of patients free of GVHD at Day 50 (p-value 0.05) and Day 80 (p-value 0.005) and the median time to treatment failure through Day 80 (p-value 0.0226), as well as a 66% reduction in mortality among patients randomized to orBec ® at 200 days post-transplant with only 5 patient (8%) deaths in the orBec ® group compared to 16 patient (24%) deaths in the placebo group (p-value 0.0139). At one year post-randomization in the Phase 3 trial, 18 patients (29%) in the orBec ® group and 28 patients (42%) in the placebo group died within one year of randomization (46% reduction in mortality, p-value 0.04).

orBec ® represents a first-of-its-kind oral, locally acting therapy tailored to treat the GI manifestation of acute GVHD, the organ system where GVHD is most frequently encountered and highly problematic. orBec ® is intended to reduce the need for systemic immunosuppressive drugs to treat GI GVHD. orBec ® is formulated for oral administration in GVHD patients as a single product consisting of two tablets; one tablet is intended to release BDP in the proximal portions of the GI tract, and the other tablet is intended to release BDP in the distal portions of the GI tract. Oral BDP may also have application in treating other GI disorders characterized by severe inflammation.

In addition to issued patents and pending worldwide patent applications, orBec ® benefits from orphan drug designations in the US and in Europe for the treatment of GI GVHD, as well as an orphan drug designation in the US for the prevention of acute GVHD and the treatment of chronic GI GVHD. Orphan drug designations provide for 7 and 10 years of market exclusivity upon approval in the US and Europe, respectively. orBec ® has also received Fast Track designation from the FDA for the treatment of GI GVHD.

GVHD is a painful, debilitating and sometimes fatal disease. It is a common disorder among immunocompromised cancer patients after receiving allogeneic stem cell or bone marrow transplants. Unlike organ transplants where the patient’s body may reject the organ, in GVHD it is the donor cells that begin to attack the patient’s body – most frequently the gut, liver and skin. Patients with mild-to-moderate GI GVHD typically develop symptoms of anorexia, nausea, vomiting and diarrhea. If left untreated, GI GVHD can progress to ulcerations in the lining of the GI tract, and in its most severe form, can be fatal.

Systemic immunosuppressive agents such as prednisone, which are the current standard treatments for GVHD, are associated with high mortality rates due to infection and debility. Further, these drugs have not been approved for treating GVHD in the US or European Union, but rather are used off-label for this indication.

About the Sigma-Tau Group

The Sigma-Tau Group is a leading international pharmaceutical group with wholly Italian-owned capital that invests in the research, development and marketing of innovative and effective treatments to improve patient well-being and quality of life. Sigma-Tau was founded in Italy in 1957 and achieved global revenues of € 673 million in 2010. Sigma-Tau Group has headquarters in Pomezia (Rome, Italy), and subsidiaries in France, Switzerland, the Netherlands, Belgium, Portugal, Germany, UK, India, US and Spain, these latter two with a production plant. It has over 2400 employees and an extensive network of licensees worldwide.

Sigma-Tau invests on average 16% of its revenues in R&D, and employs approximately 400 researchers currently working on its significant discovery pipeline, studying, through clinical and pre-clinical trials, 26 different molecules, mostly (11) new and original, and 18 owned by the Sigma-Tau Group. Therapeutic areas in which the company's research and development are focused include rare and neglected diseases, oncology, immunology and biotech. For more information about the Sigma-Tau Group visit: www.sigma-tau.it .

About Sigma-Tau Pharmaceuticals, Inc.

Sigma-Tau Pharmaceuticals, Inc. based in Gaithersburg, Maryland, is a wholly-owned subsidiary of the Sigma-Tau Group, and is dedicated solely to the global development and commercialization of medicines for patients with rare diseases. Since 1989, the Company’s products have been focused on rare diseases, including kidney disease, certain genetic disorders and cancers. With more than 7,000 identified rare diseases that affect approximately 25 million patients in the Unites States, Sigma-Tau places its considerable scientific resources behind the development and commercialization of compounds that benefit the few. The Company has a substantial development program focused on transplant, cancer, inherited genetic disorders, malaria, and other areas of unmet medical need. For more information about the company, visit www.sigmatau.com .

About Soligenix, Inc.

Soligenix is a late-stage biopharmaceutical company developing products to treat life-threatening side effects of cancer treatments and serious gastrointestinal diseases, and vaccines for certain bioterrorism agents. Soligenix’s lead product, orBec ® (oral beclomethasone dipropionate), is a potent, locally acting corticosteroid being developed for the treatment of acute gastrointestinal Graft-versus-Host disease (GI GVHD), a common and potentially life-threatening complication of hematopoietic cell transplantation. orBec ® is currently the subject of a $1.2 million FDA Orphan Products Grant-supported confirmatory Phase 3 clinical trial for the treatment of acute GI GVHD. Soligenix is also conducting a National Cancer Institute (NCI)-supported Phase 1/2 clinical trial of SGX201 in the prevention of acute radiation enteritis. Additionally, Soligenix has a Lipid Polymer Micelle (LPM™) drug delivery technology for the oral delivery of leuprolide for the treatment of prostate cancer and endometriosis.

Through its Biodefense Division, Soligenix is developing biomedical countermeasures pursuant to the Project BioShield Act of 2004. Soligenix’s lead biodefense product in development is a recombinant subunit vaccine called RiVax™, which is designed to protect against the lethal effects of exposure to ricin toxin. RiVax™ has been shown to be well tolerated and immunogenic in a Phase 1 clinical trial in normal volunteers. RiVax™ is currently the subject of a $9.4 million NIAID grant supporting development of new heat stable vaccines. Soligenix is also developing SGX202 for the treatment of radiation injury and has recently released positive preliminary preclinical results in a canine gastrointestinal acute radiation syndrome model.

For further information regarding Soligenix, Inc., please visit the Company's website at www.soligenix.com .

This press release contains forward-looking statements that reflect Soligenix, Inc.'s current expectations about its future results, performance, prospects and opportunities. Statements that are not historical facts, such as "anticipates," "believes," "intends," or similar expressions, are forward-looking statements. These statements are subject to a number of risks, uncertainties and other factors that could cause actual events or results in future periods to differ materially from what is expressed in, or implied by, these statements. Soligenix cannot assure you that it will be able to successfully develop or commercialize products based on its technology, including orBec ® , SGX201, RiVax™, and LPM TM , particularly in light of the significant uncertainty inherent in developing vaccines against bioterror threats, manufacturing and conducting preclinical and clinical trials of vaccines, and obtaining regulatory approvals, that its cash expenditures will not exceed projected levels, that product development and commercialization efforts will not be reduced or discontinued due to difficulties or delays in clinical trials or due to lack of progress or positive results from research and development efforts, that it will be able to successfully obtain any further grants and awards, maintain its existing grants which are subject to performance, enter into any biodefense procurement contracts with the US Government or other countries, that the US Congress may not pass any legislation that would provide additional funding for the Project BioShield program, that it will be able to patent, register or protect its technology from challenge and products from competition or maintain or expand its license agreements with its current licensors, or that its business strategy will be successful. Important factors which may affect the future use of orBec ® for gastrointestinal GVHD include the risks that: the FDA's requirement that Soligenix conduct additional clinical trials to demonstrate the safety and efficacy of orBec ® will take a significant amount of time and money to complete and positive results leading to regulatory approval cannot be assumed; Soligenix is dependent on the expertise, effort, priorities and contractual obligations of third parties in the clinical trials, manufacturing, marketing, sales and distribution of its products; orBec ® may not gain market acceptance if it is eventually approved by the FDA; and others may develop technologies or products superior to orBec ® . Factors affecting the development and use of SGX201 and LPM TM are similar to those affecting orBec ® . These and other factors are described from time to time in filings with the Securities and Exchange Commission, including, but not limited to, Soligenix's reports on Forms 10-Q and 10-K. Unless required by law, Soligenix assumes no obligation to update or revise any forward-looking statements as a result of new information or future events.

Evan Myrianthopoulos

Chief Financial Officer

(609) 538-8200 | www.soligenix.com

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