Soligenix Announces Publication of Successful Preclinical Efficacy and Immunogenicity Results for Ricin Toxin Vaccine

Princeton, NJ –March 11 2015 – Soligenix, Inc. (OTCQB: SNGX) (Soligenix or the Company), a late-stage biopharmaceutical company developing products that address unmet medical needs in the areas of inflammation, oncology and biodefense, announced today the publication of data demonstrating complete protection and immunogenicity of its ricin vaccine, RiVax™, in preclinical studies, with analyses of previous human clinical samples.  RiVax™ employs a derivative of recombinant ricin toxin A chain.  The use of the Company’s proprietary vaccine stabilization technology, ThermoVax™ has been previously demonstrated to enhance thermostability of RiVax™, enabling distribution without cold chain requirements.  In this work, vaccination with RiVax™ provided 100% protection for non-human primates (NHPs) subsequently exposed to lethal doses of aerosolized ricin.  Evaluation of antibodies produced by the NHPs after vaccination identified specific neutralizing antibodies which were also expressed by humans previously vaccinated with RiVax™.  The results were published online in the Proceedings of the National Academy of Sciences and are available at the following link:
http://www.pnas.org/content/early/2015/03/05/1502585112.full.pdf+html?sid=0fa9065e-5465-4bab-8940-67f32229914c .

Soligenix has been developing RiVax™ in conjunction with its heat stabilization technology, ThermoVax™, as a heat-stable biodefense vaccine.  Vaccination with RiVax™ protected all animals from acute lethal death due to aerosolized ricin exposure, in contrast to unvaccinated animals that all died within 40 hours.  Approval for the RiVax™ vaccine as an emergency countermeasure will require satisfying the “Animal Rule”, including the identification of biomarkers of RiVax™ action which can be correlated between animals and healthy human volunteer trials.  For ricin toxin exposure, the relevant biomarkers include the production of neutralizing antibodies.  Importantly, the neutralizing antibody profile produced by the vaccinated NHPs, which were subsequently completely protected against aerosol exposure, matched the profile found in samples from humans previously vaccinated with the RiVax™ vaccine.

Previous studies have also demonstrated the potential ability to combine the RiVax™ vaccine with Soligenix’s VeloThrax™ (anthrax toxin) vaccine. Results are available athttp://www.sciencedirect.com/science/article/pii/S0264410X14015758. “These data continue to demonstrate the potential of creating a thermostable ricin vaccine with the ability to avoid cold chain management and protect people against the most lethal routes of ricin exposure,” stated Christopher J. Schaber, PhD, President and Chief Executive Officer of Soligenix. “We are developing RiVax™ using ThermoVax™, our proprietary thermostabilization system, under a recent NIAID contract award of up to $24.7M over 5 years.”

These studies were performed under the aegis of a $9.4 million cooperative grant from the National Institute of Allergy and Infectious Diseases (NIAID) for the development of the ThermoVax™ technology.  The work was conducted by collaborators at the Tulane National Primate Research Center (Dr. Chad Roy), the Wadsworth Center, New York State Department of Health (including Drs. Nicolas J. Mantis and David Vance) and by the University of Texas, Southwestern (Dr. Ellen Vitetta).  The underlying ThermoVax™ has been invented by Drs. John Carpenter and Theodore Randolph at the University of Colorado and further developed in collaboration with Soligenix.

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 our proprietary vaccine candidate being developed to protect against exposure to ricin toxin, and if approved would be the first ricin vaccine.  RiVax™ has demonstrated statistically significant (p < 0.0001) preclinical survival results in a lethal aerosol exposure non-human primate model, and has also been shown to be well tolerated and immunogenic in two Phase 1 clinical trials in healthy volunteers.  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 grants from both NIAID and the US Food and Drug Administration (FDA), which were awarded to Soligenix and to Dr. Ellen Vitetta and colleagues at the University of Texas Southwestern (UTSW) where the vaccine originated.  Most recently, Soligenix was awarded a contract valued at up to $24.7 million by the US Department of Health and Human Service’s National Institutes of Health (NIH) (specifically funded by the National Institute of Allergy and Infectious Diseases or NIAID) to advance the development of Soligenix’s thermostabilization technology, ThermoVax™, combined with the company’s ricin toxin vaccine, Rivax™ as a medical countermeasure (MCM) to prevent the effects of ricin exposure.

RiVax™ has been granted orphan drug designation by the FDA for the prevention of ricin intoxication.

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 as much as 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 late-stage biopharmaceutical company developing products that address unmet medical needs in the areas of inflammation, oncology and biodefense. Our BioTherapeutics business segment is developing SGX301 as a first-in-class photo-dynamic therapy utilizing safe visible light for the treatment of cutaneous T-cell lymphoma, proprietary formulations of oral beclomethasone 17,21-dipropionate (BDP) for the prevention/treatment of gastrointestinal (GI) disorders characterized by severe inflammation including pediatric Crohn’s disease (SGX203) and acute radiation enteritis (SGX201), and our novel innate defense regulator technology (SGX942) for the treatment of oral mucositis.

Our Vaccines/BioDefense business segment includes active development programs for RiVax™, our ricin toxin vaccine candidate, VeloThrax™, our anthrax vaccine candidate, OrbeShield™, our GI acute radiation syndrome therapeutic candidate and SGX101 and SGX943, our melioidosis therapeutic candidates. The development of our vaccine programs incorporates the use of our proprietary heat stabilization platform technology, known as ThermoVax™.  Currently, this business segment is supported with up to $57 million in government grant and contract funding from the National Institute of Allergy and Infectious Diseases (NIAID) and the Biomedical Advanced Research and Development Authority (BARDA).  Additionally, Soligenix has an exclusive worldwide collaboration with Intrexon Corporation (NYSE: XON) focused on the joint development of SGX101 for the treatment for melioidosis.

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.