Tonix Pharmaceuticals presents data on TNX-801 at Immunology Symposium

Tonix Pharmaceuticals announced data presented at a symposium hosted by the Department of Medical Microbiology & Immunology and the Li Ka Shing Institute of Virology to celebrate the career and honor the retirement of Tonix’s collaborator, David Evans, Ph.D., FCAHS, Emeritus Professor, Department of Cell Biology, University of Alberta. The presentation titled, “Using Synthetic Biology to Battle Mpox”, detailed the Company’s vaccine platform, led by TNX-801 for preventing mpox. TNX-801 is an attenuated live-virus vaccine based on synthesized horsepox that has been shown to provide single-dose immune protection against a monkeypox challenge with better tolerability than 20th century vaccinia live-virus vaccines in animals. TNX-801 is structurally closer to 19th century live-virus vaccinia vaccines than 20th century versions. Genomic sequencing of archaic smallpox vaccines has shown that vaccines used prior to 1900 would be called ‘horsepox’ today. While effective against smallpox as single-dose vaccines, 20th century vaccines have diverged from horsepox-like progenitors to have greater virulence and toxicity than TNX-801 in animals. The U.S. Food and Drug Administration recently approved ACAM2000 from Emergent Technologies for preventing mpox.4 ACAM200 is a live-virus vaccine derived from a 20th Century vaccinia vaccine. ACAM2000 carries a Black Box warning on its package insert labeling warning of tolerability issues, including myocarditis and pericarditis, encephalitis, encephalomyelitis, encephalopathy, progressive vaccinia, generalized vaccinia, severe vaccinial skin infections, erythema multiforme major, eczema vaccinatum resulting in permanent sequelae or death, and risks in certain individuals that may result in severe disability, permanent neurological sequelae and/or death.5 The Jynneos vaccine from Bavarian Nordic is a non-replicating vaccinia vaccine that is FDA-approved for mpox with a two-dose regimen requiring sterile injection.6 Single-dose TNX-801 has advantages over non-replicating vaccinia vaccines which require two doses. Percutaneous TNX-801 has advantages over vaccines which require sterile injection. The durability of protection from 19th century live-virus vaccinia vaccines was believed to last decades or even be live-long. Consequently, single-dose TNX-801 is believed to stimulate long-lived T cell immunity. Consequently, TNX-801 will not require multiple repeated doses at six-month intervals like mRNA vaccines.7 Also, the stability of live-virus vaccines, particularly in lyophilized form, eliminates the need for ultra-cold storage which complicates the widespread use of mRNA vaccines in Africa, where they are needed most right now. Tonix’s focus on single-dose vaccines adheres to recommendations by the Bipartisan Commission on Biodefense8, and the U.S. National Academies of Science. For example, the NAS report highlights the difficulty of a case-contact or “ring” vaccination strategy with even a two-dose regimen. In the presentation, Tonix highlighted positive preclinical efficacy data, demonstrating that TNX-801 protected animals against lethal challenge with intratracheal clade I monkeypox virus.10 An outbreak of Clade I mpox has recently been declared a Public Health Emergency of International Concern by the World Health Organization.11,12 Starting from an outbreak in the Democratic Republic of the Congo, clade I mpox has spread to several Central African Countries and cases have been reported in Sweden, Thailand and Singapore. According to the U.S. Centers for Disease Control and Prevention and other experts, there is a significant risk that clade I strain may appear in the U.S.13 Clade I mpox is typically associated with higher case fatality rates than clade II mpox. After a single dose vaccination, TNX-801 prevented clinical disease and lesions and also decreased shedding in the mouth and lungs of animals challenged with clade I monkeypox.10 These findings are consistent with TNX-801 inducing mucosal immunity and suggest TNX-801 has the ability to block forward transmission, similar to Dr. Edward Jenner’s vaccinia vaccine, descendants of which eradicated smallpox and kept mpox out of the human population. The presentation at University of Alberta included results from Tonix scientists at the Research and Development Center (RDC) in Frederick, Md. Data from a manuscript showed that TNX-801 is highly attenuated relative to 20th century vaccinia vaccines in in immunocompromised animals.14 New data showed TNX-801 is unable to spread in blood or tissues in these animals, even at an approximately 100-Fold higher dose than 20th century vaccinia vaccines. In addition to characterizing TNX-801’s activity and tolerability, Tonix scientists have explored the characteristics of the monkeypox virus. The prior 2022 global clade IIb mpox outbreak, affected over 90,000 persons in countries where mpox previously had not been endemic, including Europe and the US. The spread of clade IIb strain mpox in 2022 underscores the pandemic potential of mpox. Data presented show that monkeypox clade IIb from a 2022 isolate in Massachusetts is 10,000- to 100,000-fold more attenuated than clade IIa isolates from 2003. The attenuation of clade II monkeypox in the recent 2022 outbreak may have contributed to its greater dissemination. The new and more lethal clade I monkeypox has not yet been analyzed.