Soligenix Announces Completion of Enrollment and Preliminary Safety Results of a Phase 1B Clinical Trial for RiVax™

PRINCETON, N.J., Nov. 2, 2010 /PRNewswire-FirstCall/ -- Soligenix, Inc. (Soligenix or the Company) (OTC Bulletin Board: SNGX), a late-stage biopharmaceutical company, reported today that it has completed enrollment of its Phase 1B clinical trial of RiVax™, a ricin subunit vaccine, in healthy volunteers. Preliminary results indicate that RiVax™ appears safe at all doses tested in volunteers. This trial is designed to assess the duration of immune responses using an adjuvant formulation of RiVax™ over a period of more than one year after vaccination.

This ongoing Phase 1B trial is intended to evaluate the safety and immunogenicity of an improved formulation of RiVax™ containing an adjuvant and is anticipated to result in longer lasting and higher levels of protective antibodies. The current trial employs an escalating dose strategy in which volunteers receive three intramuscular doses of vaccine at six-week intervals, matching many commonly employed vaccination regimens.  The trial is being funded by a grant from the FDA's Orphan Products Division.  The principal investigator of the study is Ellen Vitetta, PhD, Director of the University of Texas Southwestern Medical Center's Cancer Immunobiology Center.  Analysis of human immunogenicity and complementary non-human primate efficacy is expected during the first half of 2011.

RiVax™ safety and immunogenicity has previously been observed in a Phase 1 clinical trial of the subunit vaccine without an adjuvant. Results demonstrated that the adjuvant-free RiVax™ was well tolerated and induced antibodies in humans that neutralized ricin toxin in tissue culture and in mice.  Serum antibodies that neutralize ricin are expected to function to reduce mortality and morbidity from exposure to ricin, including the aerosol route. The new formulation employs a well characterized adjuvant to induce protective, neutralizing antibodies in humans.  

"We are very encouraged that we have demonstrated safety at the highest vaccine doses in the current trial volunteers," said Dr. Vitetta. "This study with the adjuvanted formulation will further guide us in determination of safe dose levels of RiVax™ that induce the highest levels of antibodies that are correlated to efficacy. We are looking forward to completing the analysis of the immune responses induced by RiVax™ in the sera of volunteers up to one year after the last vaccination."

"We are anticipating that the adjuvant form of the vaccine will induce antibodies in humans that are correlated with long-term immunity to ricin toxin," said Robert N. Brey, PhD, Chief Scientific Officer of Soligenix. "We are concurrently validating those immunological correlates in animal model systems with our team of collaborators."

About RiVax™

RiVax™ is Soligenix's proprietary recombinant subunit vaccine developed to protect against exposure to ricin toxin. RiVax™ induces a protective immune response in animal models of ricin exposure and is currently being evaluated in humans. One human Phase 1 clinical trial has been completed and a second trial has recently completed enrollment.

Results of the first Phase 1 clinical trial of RiVax™ indicated that the immunogen was safe and induced antibodies anticipated to protect humans from ricin exposure. The outcome of the study was published in the Proceedings of the National Academy of Sciences (Vitetta et al., 2006, PNAS, 105:2268-2273). The second trial, sponsored by University of Texas (UT) Southwestern, is currently evaluating a more potent formulation of RiVax™. Soligenix has developed processes for large-scale manufacturing and is further establishing correlates of the human immune response in non-human primates.

The development of RiVax™ has been sponsored through a series of overlapping challenge grants (UC1) and cooperative grants (U01) from the NIH which were granted to Soligenix and to UT Southwestern where the vaccine originated. The second clinical trial is being supported by a grant to UT Southwestern from the US Food and Drug Administration's Office of Orphan Products Development. Soligenix and UT Southwestern have collectively received approximately $25 million in grant funding from the NIH for development of RiVax™ and related vaccine technologies.

About Ricin Toxin

Ricin toxin is a plant toxin thought to be a bioterror threat because of its stability and high potency as well as the large worldwide reservoir created as a by-product of castor oil production. Ricin toxin is relatively easy to produce and exposure to small amounts, especially by inhalation, can lead to lung damage, nausea, fever, abdominal pain, and death within several days.  Exposure to ricin results in local tissue necrosis, and general organ failure leading to death within several days of exposure. The potential use of ricin toxin as a biological weapon has been highlighted in an FBI terrorism report, which states that "Ricin and the bacterial agent anthrax are emerging as the most prevalent agents involved in WMD investigations" (http://www.fbi.gov/stats-services/publications/terrorism-2002-2005).

There are currently no effective means to prevent the effects of ricin intoxication. The successful development of an effective vaccine against ricin toxin may act as a deterrent against the actual use of ricin as a biological weapon and could be used in rapid deployment scenarios in the event of a biological attack. RiVax™ would potentially be added to the Strategic National Stockpile and dispensed in the event of a terrorist attack.

About Soligenix, Inc.

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 or BDP), 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 $1.2M FDA Orphan Products Grant supported confirmatory Phase 3 clinical trial for the treatment of acute GI GVHD. Soligenix is also conducting an NIH-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 also the subject of a $9.4 million NIH grant received by the Company supporting development of new heat stable vaccines.

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™, 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 LPMTM 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.

SOURCE Soligenix, Inc.