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Soligenix Announces Positive Survival Results with Heat Stable Ricin Toxin Vaccine

All vaccinated animals exposed to a lethal aerosol of ricin toxin survive

PRINCETON, N.J., Sept. 2, 2014 /PRNewswire/ -- Soligenix, Inc. (OTCQB: SNGX) (Soligenix or the Company), a clinical stage biopharmaceutical company focused on developing products to treat serious inflammatory diseases where there remains an unmet medical need, as well as developing several biodefense vaccines and therapeutics, announced today promising preliminary results from a preclinical study with its ricin toxin vaccine RiVax™, in a non-human primate (NHP) lethal aerosol exposure model. The study demonstrated that NHPs vaccinated with RiVax™ were completely protected against a lethal aerosol of ricin toxin with a highly significant survival benefit (p<0.002).  RiVax™, manufactured with the Company's thermostabilization platform technology ThermoVax™, was used to vaccinate NHPs to assess efficacy against lung exposure to ricin toxin in an animal model that is anticipated to respond to vaccination similarly to humans.  ThermoVax™ provides for stabilized, lyophilized (freeze-dried) subunit vaccines that are resistant to exposure to heat, avoiding refrigeration during storage and distribution.

In this pilot study, the ability of the stabilized RiVax™ vaccine to protect against an aerosolized form of ricin toxin was evaluated.  Animals were exposed to an aerosol of ricin toxin 3-5 times the amount that is known to result in death of untreated animals.  In the case of vaccinated NHPs, the vaccine regimen was safe and well-tolerated, with all of the animals developing antibodies in their sera that neutralized the activity of ricin toxin.  More importantly, all of the NHPs in the RiVax™-vaccinated treatment group survived when exposed to the respiratory aerosol of ricin toxin, with no apparent signs of gross lung damage.   Conversely, all NHPs in the unvaccinated treatment group died within approximately 36 hours of exposure to aerosolized ricin while developing severe lung damage, including hemorrhaging. 

"We are extremely pleased with the positive preliminary efficacy results with RiVax™ in NHPs.  This particular study is a critical step along the path of establishing efficacy under the FDA 'animal rule' which dictates that efficacy in animals must be ascertained in cases where a drug or vaccine cannot be ethically tested for efficacy in humans," stated Christopher J. Schaber, PhD, President and Chief Executive Officer of Soligenix.  "It is clear that vaccination with heat stable RiVax™ resulted in robust protection against lung exposure, the most dangerous and likely way that ricin toxin could be used.  We anticipate further development of RiVax™ in order to conduct human safety and immunogenicity trials along with advanced manufacturing."

The vaccination and exposure studies were conducted at the Tulane National Primate Research Center (TNPRC) under the direction of Dr. Chad Roy, Director of Infectious Disease Aerobiology.  These studies were performed under sponsorship of a National Institute of Allergy and Infectious Disease (NIAID) cooperative grant to Soligenix with TNRPC and other collaborators.

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 comes in many forms like powder, mist, pill, or pellet.  Ricin can also be dissolved in water and other liquids.  As a poison, ricin is so potent that the US Centers for Disease Control (CDC) estimates the lethal dose in humans is about the size of a grain of salt.  Exposure to ricin results in local tissue necrosis and general organ failure leading to death within several days of exposure, and is especially toxic when inhaled.  Ricin is a ribosome inactivating protein (RIP) and a potent member of the AB family of toxins.  The enzymatic ricin toxin A subunit (RTA) is an RNA-N-glycosidase which cleaves a specific adenine residue with eukaryotic 28S ribosomal RNA, leading to protein synthesis arrest and cell death.  

There are currently no effective means to prevent the effects of ricin poisoning.  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.  

About RiVax™

RiVax™ is Soligenix's proprietary recombinant subunit vaccine developed to protect against exposure to ricin toxin.  With RiVax™, Soligenix is a world leader in the area of ricin toxin vaccine research.

RiVax™ contains a genetically altered version of RTA chain containing two mutations that inactivate the toxicity of the ricin molecule.  A Phase 1A clinical trial was conducted with a formulation of RiVax™ that did not contain an adjuvant.  This trial revealed dose dependent seroconversion as well as lack of toxicity of the molecule when administered intramuscularly to human volunteers. The adjuvant-free formulation of RiVax™ induced toxin neutralizing antibodies that lasted up to 127 days after the third vaccination in several individuals.  To increase the longevity and magnitude of toxin neutralizing antibodies, RiVax™ was formulated with an adjuvant of aluminum salts (known colloquially as Alum) for a Phase 1B clinical trial.  Alum is an adjuvant that is used in many human vaccines, including most vaccines used in infants.  The results of the Phase 1B study indicated that Alum-adjuvanted RiVax™ was safe and well tolerated, and induced greater ricin neutralizing antibody levels in humans than adjuvant-free RiVax™.  In preclinical animal studies, the Alum formulation of RiVax™ also induced higher titers and longer lasting antibodies than the adjuvant-free vaccine. 

The development of RiVax™ has been sponsored through a series of overlapping grants from both NIAID and the US Food and Drug Administration (FDA), which were granted to Soligenix and to University of Texas Southwestern (UTSW) where the vaccine originated. To date, Soligenix and Dr. Ellen Vitetta and colleagues at UTSW have collectively received approximately $25 million in grant funding from the US government for development of RiVax™ and related vaccine technologies.  RiVax™ would potentially be added to the Strategic National Stockpile and dispensed in the event of a terrorist attack.

About ThermoVax

ThermoVax™ is a technology that is designed to eliminate the standard cold chain production, distribution and storage logistics required for most vaccines.  Cold chain requirements add considerable cost to the production and storage of current conventional vaccines.  According to the Biopharma Cold Chain Sourcebook of 2010, 98% of all vaccines (with a total value of $20.6 billion) require shipment through cold chain.  Elimination of the cold chain would also enhance the utility of these vaccines for emerging markets and for other applications requiring but lacking reliable cold chain capabilities.  Further, the World Health Organization (WHO) reports that 50% of all global vaccine doses are wasted because they are not kept within required temperature ranges.  NIAID has also highlighted the priority of technologies for biodefense vaccines that focus on broad spectrum approaches including vaccine adjuvants and temperature stabilization for long shelf life, rapid onset of immunity, and surge capacity for production.  For vaccines that are intended for long-term stockpiling, such as for use in biodefense or in pandemic situations, the utilization of ThermoVax™ has the potential to facilitate easier storage and distribution of Strategic National Stockpile vaccines in emergency situations. 

The technology utilizes precise lyophilization of protein immunogens with conventional aluminum adjuvants in combination with secondary adjuvants for rapid onset of protective immunity with the fewest number of vaccinations.  RiVax™ is extremely labile in liquid form requiring careful management under refrigerated conditions at 4 degrees Celsius (39 degrees Fahrenheit).  By employing ThermoVax™ during their final formulation, it is possible to produce stable and potent vaccines that are capable of withstanding temperatures at least as high as 40 degrees Celsius (104 degrees Fahrenheit) for up to one year. 

The underlying technology has been developed by Drs. John Carpenter and Theodore Randolph at the University of Colorado. The vaccine technology has been developed to date in collaboration with SRI International, the University of Kansas, the Wadsworth Center of the New York State Department of Health, and the Tulane National Primate Research Center under the sponsorship of the cooperative grant from NIAID.

About Soligenix, Inc.

Soligenix is a clinical stage biopharmaceutical company focused on developing products to treat serious inflammatory diseases where there remains an unmet medical need, as well as developing several biodefense vaccines and therapeutics. Soligenix is developing proprietary formulations of oral BDP (beclomethasone 17,21-dipropionate) for the prevention/treatment of gastrointestinal disorders characterized by severe inflammation, including pediatric Crohn's disease (SGX203), acute radiation enteritis (SGX201) and chronic Graft-versus-Host disease (orBec®), as well as developing its novel innate defense regulator (IDR) technology SGX942 for the treatment of oral mucositis.  

Through its BioDefense Division, Soligenix is developing countermeasures pursuant to the Biomedical Advanced Research and Development Authority (BARDA) Strategic Plan of 2011-2016 for inclusion in the US government's Strategic National Stockpile. Soligenix's biodefense products in development are a recombinant subunit vaccine called RiVax™, which is designed to protect against the lethal effects of exposure to ricin toxin and VeloThrax™, a vaccine against anthrax exposure. RiVax™ has been shown to be well tolerated and immunogenic in two Phase 1 clinical trials in healthy volunteers. Both RiVax™ and VeloThrax™ are currently the subject of a $9.4 million National Institute of Allergy and Infectious Diseases (NIAID) grant supporting development of Soligenix's new vaccine heat stabilization technology known as ThermoVax™.  Soligenix is also developing OrbeShield™ for the treatment of gastrointestinal acute radiation syndrome (GI ARS) under a BARDA contract award valued up to $26.3 million and a NIAID contract award valued up to $6.4 million. OrbeShield™ has previously demonstrated statistically significant preclinical survival results in a canine model of GI ARS funded by NIAID.  Additionally, Soligenix has an exclusive worldwide collaboration with Intrexon Corporation (NYSE: XON) focused on the joint development of a treatment for melioidosis, a high priority biothreat and an area of unmet medical need.

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, including but not limited to, potential market sizes, patient populations and clinical trial enrollment.  Statements that are not historical facts, such as "anticipates," "estimates," "believes," "intends," "potential," 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, achieve regulatory approval for or commercialize products based on its technologies, particularly in light of the significant uncertainty inherent in developing vaccines against bioterror threats conducting preclinical and clinical trials of vaccines, obtaining regulatory approvals and manufacturing vaccines, 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 funding to support product development and commercialization efforts, including grants and awards, maintain its existing grants which are subject to performance requirements, enter into any biodefense procurement contracts with the US Government or other countries, that it will be able to compete with larger and better financed competitors in the biotechnology industry, that changes in health care practice, third party reimbursement limitations and Federal and/or state health care reform initiatives will not negatively affect its business, or that the US Congress may not pass any legislation that would provide additional funding for the Project BioShield program.  These and other risk 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.

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