Soligenix Announces Publication of Combination Ricin/Anthrax Vaccine Data

Princeton, NJ – December 29, 2014 – 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 that the combination of RiVax™ and VeloThrax™ induces protective immunity to both ricin toxin and anthrax toxin exposure.  RiVax™ is the Company’s candidate vaccine for the prevention of exposure to ricin toxin using a unique antigen that is completely devoid of the toxic activity of ricin.  VeloThrax™ is the Company’s candidate vaccine that employs a derivative of recombinant protective antigen, termed Dominant Negative Inhibitor (DNI), which is a candidate for inclusion in a next generation anthrax vaccine.  The results were published online in Vaccine and are available at the following link: http://www.sciencedirect.com/science/article/pii/S0264410X14015758.

The combination treatment of RiVax™ plus VeloThrax™ was compared to treatment with either RiVax™ alone or VeloThrax™ alone.  The combination treatment was able to provide protection against subsequent challenge with both ricin and anthrax toxin in animal studies.  In contrast, mice administered the RiVax™ vaccine were protected from ricin challenge but not anthrax toxin challenge and mice administered VeloThrax™ were protected from anthrax toxin challenge but not ricin challenge. These challenges were given at least 6 months after vaccination and titer levels from the combination were evaluated up to 200 days post vaccination.
Soligenix performed these studies in collaboration with the Wadsworth Center, New York State Department of Health, with Dr. Nicolas J. Mantis, Dr. David Vance and collaborators under the aegis of a $9.4 million cooperative grant from the National Institute of Allergy and Infectious Diseases (NIAID).

“We are pleased that we have been able to show that a multivalent vaccine for both anthrax and ricin is feasible.  The demonstration of simultaneous immunity to ricin and anthrax toxin is a step towards vaccines that can be used in the event of a national emergency,” stated Christopher J. Schaber, PhD, President and Chief Executive Officer of Soligenix. “We are continuing to develop RiVax™ using ThermoVax™, our proprietary vaccine thermostabilization technology for the stockpiling and distribution of vaccines outside of normal cold chain requirements, under a recent NIAID contract award of up to $24.7M over 5 years.  Ultimately, we intend to develop the combination vaccine using this same technology.”

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.

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 < 0.002) 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 overlapping grants from both NIAID and the US Food and Drug Administration (FDA), which were granted 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 Anthrax 

Anthrax is an acute infectious disease that is easily transmitted to humans by environmentally durable spores that are produced by gram positive bacterium Bacillus anthracis. Because the spores are robust and contagious, anthrax is considered a Category A bioterror threat.  Anthrax infection can occur in three forms: cutaneous (skin), inhalation, and gastrointestinal. Inhaled spores can cause a rapidly progressing form of anthrax since the spores are transported to lymph nodes near the lungs where they germinate, releasing vegetative bacteria into the bloodstream.  After infection in the bloodstream, the bacteria secrete a complex series of toxin components that make up anthrax toxin, resulting in overwhelming toxemia that causes shock and organ failure. The toxin component that binds to the surface of cells is Protective Antigen (PA).  Antibodies targeting PA can neutralize the secreted toxins, and recombinant PA (rPA) and its derivatives are targets for development of highly purified next generation anthrax vaccines.  PA is the major antigen in the currently licensed anthrax vaccine adsorbed (AVA, Biothrax™).

Treatment of anthrax involves long-term antibiotic therapy, since ungerminated spores can lie dormant in the lungs for up to 60 days. Only a few inhaled spores can cause inhalational anthrax. Once the toxin has entered the bloodstream, antibiotics are ineffective, and only toxin-specific therapy is effective. Passively transferred antibodies can neutralize anthrax toxins and can be used post-exposure in conjunction with antibiotics. Because of the long residence time of spores in the lung, it is possible to vaccinate post-exposure, but the onset of neutralizing antibodies must occur during the period of antibiotic therapy.

About VeloThrax™

VeloThrax™ is Soligenix’s proprietary vaccine to prevent exposure to anthrax. VeloThrax™ consists of a hyperimmunogenic derivative, termed DNI (Dominant Negative Inhibitor), of rPA (recombinant protective antigen) that is formulated with adjuvants to induce rapid protective immunity in fewer vaccinations than the currently licensed anthrax vaccine.  The DNI vaccine antigen is an analog of rPA containing two mutations that prevent translocation of the anthrax holotoxin into cells, resulting in higher immune responses.  It has been shown that animals vaccinated with the DNI antigen induced higher levels of antibodies to toxin and maintained high levels of protective antibody titers for up to one year without booster injections of antigen. The DNI vaccine was originally developed in the laboratory of Dr. John Collier and colleagues at Harvard University and has been developed as a post exposure therapeutic for exposure to anthrax.

Soligenix has obtained an exclusive license with Harvard for the development of DNI as a pre- and post exposure vaccine for anthrax.  When combined with ThermoVax™ technology, the DNI vaccine has also shown stability at temperatures as high as 70 degrees Celsius (158 degrees Fahrenheit).  The development of VeloThrax™ using the DNI antigen has been sponsored through a NIAID cooperative grant to Soligenix and is a candidate for a next generation anthrax vaccine.

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™ and VeloThrax™ are extremely labile in their 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 a 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, 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 may contain 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.