Soligenix Announces Successful Protection using a Bivalent Thermostabilized Filovirus Vaccine

Soligenix, Inc. (Nasdaq: SNGX) (Soligenix or the Company), a late-stage biopharmaceutical company focused on developing and commercializing products to treat rare diseases where there is an unmet medical need, announced today 100% protection of non-human primates (NHPs) against lethal Sudan ebolavirus (SUDV) challenge using a bivalent, thermostabilized vaccine formulated in a single vial, reconstituted only with water immediately prior to use. This milestone is part of an ongoing collaboration with the University of Hawaiʻi at Mānoa (UHM), demonstrating the successful presentation of one or more antigen(s) within the same formulation while maintaining full potency and thermostability. It further demonstrates the broad applicability of the vaccine platform, and its potential role in the US government's initiative for pandemic preparedness.  This same heat stable vaccine platform has also been applied to the development of a COVID-19 vaccine, CiVax™, which the Company anticipates testing against the new omicron variant, having shown immunogenicity against previous variants including delta.

The antigens and adjuvants used in this study have been previously shown to protect NHPs from subsequent infection, and represent the only recombinant subunit vaccines that have demonstrated efficacy against Zaire ebolavirus and other filoviruses in NHPs. Lyophilization of the antigens within monovalent vaccine formulations has also been demonstrated to thermostabilize the antigens at temperatures as high as 40 degrees Celsius (104 degrees Fahrenheit) for up to 12 weeks, enabling storage at ambient temperature. No currently approved lyophilized vaccine that contains adjuvant is presented in a single vial format and there are few reports of successfully using nano-emulsions in lyophilized formulations. Previous work has demonstrated the use of a single vial platform to co-lyophilize antigen(s) and a nano-emulsion adjuvant, CoVaccine HT™, maintaining key adjuvant stability characteristics including particle size and colloidal stability, as well as maintaining immunogenicity. This most recent milestone confirms that in the context of lethal challenge with Sudan ebolavirus, complete protection is maintained with the thermostabilized formulation.

"Filoviruses such as Zaire ebolavirus, Sudan ebolavirus and Marburg marburgvirus are some of the most lethal viruses known, and they are endemic in areas of the world where the power supply and distribution network can be uncertain. There are no vaccines for either Sudan ebolavirus or Marburg marburgvirus, while vaccines for Zaire ebolavirus are constrained by cold chain logistics. A heat stable vaccine in a single vial format would significantly enhance any public health preparedness or response to a new outbreak, at its source," stated Axel Lehrer, PhD, Associate Professor, Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine (JABSOM), UHM. "Our work to date has demonstrated the feasibility of rapid and efficient manufacturing, as well as the ability to thermostabilize multiple antigens that can then be stored at temperatures exceeding 100 degrees Fahrenheit. Having a vaccine platform available such as this has the potential to accelerate worldwide vaccination campaigns addressing future health emergencies, including another global pandemic like the one we are unfortunately experiencing with COVID-19."

"Our next generation combined vaccine platform includes three major components: a robust protein manufacturing process that has been demonstrated on multiple protein antigens, a novel nano-emulsion adjuvant which induces broad immunity and a formulation procedure which enables thermostabilization of the combination of adjuvant and antigen in a single vial," stated Oreola Donini, PhD, Senior Vice President and Chief Scientific Officer of Soligenix. "Elements of this vaccine platform have been utilized in our ricin toxin, filovirus and COVID-19 vaccine candidates, indicating its broad applicability. The ability to package more than one vaccine candidate in a single vial platform further adds to their developability, whether as a multivalent or individual monovalent vaccine, particularly against Marburg marburgvirus and Sudan ebolavirus where there are currently no available vaccines."

Under the Company's Public Health Solutions business segment, ongoing collaborations with Dr. Lehrer, as well as work conducted by Theodore Randolph, PhD, Professor, Center for Pharmaceutical Biotechnology, Department of Chemical and Biological Engineering at the University of Colorado, Boulder have demonstrated the feasibility of developing thermally-stable subunit protein vaccine formulations for filoviruses. The thermostabilized filovirus vaccine program is continuing to advance with the support of a National Institute of Health (NIH) grant (R01-AI132323; awarded to the University of Hawaii) and a Small Business Innovation Research grant (#1R44AI157593-01; awarded to Soligenix). Work to date has demonstrated the compatibility of lyophilizing both antigen and adjuvant in the same vial, with reconstitution with sterile water for injection immediately prior to use. This simple delivery format, as well as the compatibility with ambient storage, enables vaccines that significantly reduce the logistical hurdles that have been required for addressing the current pandemic or deployment of other Ebola virus vaccines in recent outbreaks in Central and West Africa.

About Filovirus Infection

Ebola Virus Disease is caused by one of six species of Ebolavirus, four of which are known to cause disease in humans, including its best-known member, Zaire ebolavirus (Ebola virus), with Sudan ebolavirus being the second-most common cause of human infection in this family. All species of ebolavirus belong to the Filoviridae family, a family that further contains the equally human pathogenic Marburg virus. Filoviruses are believed to be harbored in various animal species in Africa, particularly bats, although the specific reservoir host for many of these viruses is still unknown. There have been several known Ebola and Marburg Virus Disease outbreaks since 1967, with the largest outbreak starting in 2014 in Western Africa, and involved over 26,000 confirmed/probable/suspected cases with an estimated death toll of over 11,000 people according to the Centers for Disease Control and Prevention (CDC). These numbers also include some cases of virus introduction and limited spread in Europe and the United States.

Transmission of filoviruses requires direct contact with bodily fluids from an infected person or contact with infected animals. The mortality rates following filovirus infections are extremely high, and, in the absence of wide availability of effective therapeutics, are affected by the quality of supportive care available with a focus on early initiation of treatment. Resolution of the disease largely depends on the patient's own immune system. There are limited treatment options for Ebola Virus Disease and no available treatments for Sudan Virus or Marburg Virus Disease, although steady progress has also been made in development of immunotherapeutics for filoviruses beyond Zaire ebolavirus. There are approved vaccines for Ebola virus (Zaire ebolavirus), requiring stringent ultra-low cold-chain storage, but no efficacious vaccines are yet available for Marburg virus (Marburg marburgvirus) or Sudan virus (Sudan ebolavirus).

Filoviruses are one of the virus families identified as having the ability to cause pandemics. On the heels of the COVID-19 pandemic the US government is accelerating its investment in pandemic preparedness, including having "the ability to rapidly make vaccines effective against any virus family".  Specific initiatives have been spear-headed by the White House and Biden-Harris administration, as evidenced by the "American Pandemic Preparedness: Transforming Our Capabilities" white paper released in September 2021.

About John A. Burns School of Medicine, University of Hawai'i at Manoa

The University of Hawai'i at Manoa is one of the most ethnically diverse institutions of higher education. Hawai'i's cultural diversity and geographical setting affords the JABSOM a unique research environment to excel in health disparity research. JABSOM faculty bring external funding of about $40 million annually into Hawai'i.

About the University of Colorado Center for Pharmaceutical Biotechnology

The University of Colorado Center for Pharmaceutical Biotechnology is a research consortium operated jointly between the University of Colorado, Boulder, and the University of Colorado Anschutz Medical Campus. Housed within the Departments of Chemical and Biological Engineering and the Skaggs School of Pharmacy, the Center works with pharmaceutical industry partners to address questions regarding stability and delivery of biopharmaceutical drugs and vaccines.

About Soligenix, Inc.

Soligenix is a late-stage biopharmaceutical company focused on developing and commercializing products to treat rare diseases where there is an unmet medical need. Our Specialized BioTherapeutics business segment is developing and moving toward potential commercialization of HyBryte™ (SGX301 or synthetic hypericin) as a novel photodynamic therapy utilizing safe visible light for the treatment of cutaneous T-cell lymphoma (CTCL). With a successful Phase 3 study completed, regulatory approval is being sought and commercialization activities for this product candidate are being advanced initially in the U.S. Development programs in this business segment also include our first-in-class innate defense regulator (IDR) technology, dusquetide (SGX942) for the treatment of inflammatory diseases, including oral mucositis in head and neck cancer, and 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).

Our Public Health Solutions business segment includes active development programs for RiVax®, our ricin toxin vaccine candidate, and SGX943, our therapeutic candidate for antibiotic resistant and emerging infectious disease, and our vaccine programs targeting filoviruses (such as Marburg and Ebola) and CiVax™, our vaccine candidate for the prevention of COVID-19 (caused by SARS-CoV-2). The development of our vaccine programs incorporates the use of our proprietary heat stabilization platform technology, known as ThermoVax®. To date, this business segment has been supported with government grant and contract funding from the National Institute of Allergy and Infectious Diseases (NIAID), the Defense Threat Reduction Agency (DTRA) and the Biomedical Advanced Research and Development Authority (BARDA).

For further information regarding Soligenix, Inc., please visit the Company's website at https://www.soligenix.com and follow us on LinkedIn and Twitter at @Soligenix_Inc.

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," "hopes," "intends," "plans," "expects," "goal," "may," "suggest," "will," "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, such as experienced with the COVID-19 outbreak. 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 therapeutics and vaccines against bioterror threats, conducting preclinical and clinical trials of therapeutics and vaccines, obtaining regulatory approvals and manufacturing therapeutics and 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 U.S. 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 U.S. Congress may not pass any legislation that would provide additional funding for the Project BioShield program. In addition, there can be no assurance as to the timing or success of any of its clinical/preclinical trials. Despite the statistically significant result achieved in the HyBryte™ (SGX301) Phase 3 clinical trial for the treatment of cutaneous T-cell lymphoma, there can be no assurance that a marketing authorization from the FDA or EMA will be successful. Further, there can be no assurance that RiVax® will qualify for a biodefense Priority Review Voucher (PRV) or that the prior sales of PRVs will be indicative of any potential sales price for a PRV for RiVax®. Also, no assurance can be provided that the Company will receive or continue to receive non-dilutive government funding from grants and contracts that have been or may be awarded or for which the Company will apply in the future. 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.