Soligenix (SNGX) Announces Accelerated Publication Demonstrating Efficacy and Broad Neutralizing Activity of its COVID-19 Vaccine in Non-Human Primates

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 publication of pre-clinical immunogenicity studies for CiVax™ (heat stable COVID-19 vaccine program) demonstrating durable broad-spectrum neutralizing antibody responses, including against the Beta, Gamma and Delta variants of concern. The article, titled "Protein Vaccine Induces a Durable, More Broadly Neutralizing Antibody Response in Macaques than Natural Infection with SARS-CoV-2 P.1," has been posted as an accelerated preprint on bioRxiv (available here). The manuscript is part of the ongoing collaboration with Axel Lehrer, PhD, Associate Professor at the Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine (JABSOM), University of Hawaiʻi at Mānoa (UHM). Development continues under a non-dilutive $1.5M Small Business Innovation Research (SBIR) grant from the National Institute of Allergy and Infectious Diseases (NIAID) awarded to Soligenix in December 2020.

"This technology platform has previously demonstrated an encouraging ability to generate vaccines that are stable at ambient temperature, potentially avoiding the need for refrigerated or frozen storage and distribution," said Jerome Kim, MD, Director General of the International Vaccine Institute. "The encouraging development of a broadly neutralizing and efficacious subunit vaccine specifically for SARS-CoV-2, including the variants of concern, using the same heat stable technology platform offers greater promise for achieving worldwide vaccination in the current pandemic."

"We continue to advance our work using our vaccine platform, consisting of a robust protein manufacturing process and a thermostabilizing formulation, using the Soligenix ThermoVax® process and the CoVaccine HT™ adjuvant. The CiVax™ vaccine has demonstrated broad and robust immune responses in mice, which is recapitulated here in NHPs and further shown to yield protection against infection with COVID-19 variants of concern. Our work with CiVax™ emerged from our ongoing efforts to develop heat-stable, single-vial format vaccines for filoviruses. The ability to rapidly pivot from filovirus to SARS-CoV-2 demonstrates the broad applicability of this platform and our productive collaboration with Soligenix," stated Dr. Lehrer. "A single-vial subunit vaccine that can be shipped at ambient temperatures and that need only be reconstituted with sterile water immediately prior to use has the potential to bolster the global vaccination efforts by simplifying storage and distribution logistics."

"We believe that creating a COVID-19 vaccine, like CiVax™, with enhanced stability at elevated temperatures has the potential to lead to a faster resolution of this global pandemic, curtailing the further evolution of the virus," stated Christopher J. Schaber, PhD, President and Chief Executive Officer of Soligenix. "Moreover, the introduction of a subunit vaccine that has been built on years of proven vaccine technology may also encourage the vaccine-hesitant. This platform not only has the potential to aid in the current worldwide pandemic; but the technology platform, with its broad applicability, may also aid in the preparation for future pandemics. With these latest results, we will be expanding discussions with various funding agencies in the coming weeks."

CiVax™ is the Company's heat stable subunit vaccine candidate for the prevention of COVID-19, the disease caused by infection with SARS-CoV-2. Ongoing collaborations with Dr. Lehrer have confirmed the feasibility of developing a broadly immunogenic vaccine for COVID-19. A full-length Spike protein antigen coupled with liquid or lyophilized (thermostabilized) CoVaccine HT™ adjuvant has been tested for immunogenicity and efficacy in the context of Gamma variant challenge in non-human primates (NHPs). NHPs were vaccinated twice, three weeks apart, and were subsequently challenged with Gamma variant both intranasally and intratracheally 12 weeks later. While most vaccines tested in NHPs use a challenge date only four weeks post-vaccination when antibody levels are peaking, the use of a later challenge time in this study demonstrates the durable response elicited by this vaccine candidate. While the vaccine antigen is developed based on the Spike protein of the original SARS-CoV-2 strain, it elicited cross-neutralizing antibodies against Beta, Gamma and Delta variants of concerns. After challenge, vaccinated animals had a lower peak viral load and more rapid resolution of infectious virus, coupled with reduced lung damage. After challenge with Gamma variant, animals that were not vaccinated with CiVax™ generated a neutralizing antibody response to Beta and Gamma variants but not to the original strain and the Delta variant, demonstrating that natural infection may not yield sufficiently robust immunity. In stark contrast, CiVax™-vaccinated animals subsequently challenged with Gamma variant had enhanced neutralizing antibody responses against the original strain, as well as the Beta, Gamma and Delta variants.

While a number of vaccines are available worldwide, the requirement for cold chain shipping and timely administration, coupled with manufacturing scale-up logistics, have limited the world's supply. Rapid vaccine administration worldwide is necessary to curtail disease spread and slow or pre-empt evolution of mutations, which may abrogate the effectiveness of current vaccine approaches. Previous work with the novel CoVaccine HT™ adjuvant has indicated that it can be thermostabilized both alone and in combination with antigens, potentially yielding a single-vial presentation of CiVax™, which would not require cold chain distribution or storage.

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