Tonix Pharmaceuticals Holding Corp. presented data at the University of Alberta highlighting the potential of its mpox vaccine candidate, TNX-801, a live virus vaccine based on synthesized horsepox. The data showcased TNX-801's efficacy in protecting animals from a lethal challenge with clade I monkeypox virus, along with improved tolerability in immunocompromised animals.
TNX-801: A Potential Single-Dose Mpox Vaccine
TNX-801 is designed for percutaneous administration and has shown promise in preclinical studies. It is structurally similar to 19th-century live-virus vaccinia vaccines, which genomic sequencing suggests were horsepox-like. Unlike some 20th-century vaccines, TNX-801 has demonstrated better tolerability in animal models. The current FDA-approved vaccines for mpox include ACAM2000, which carries a Black Box warning due to tolerability issues, and Jynneos, a two-dose non-replicating vaccine.
Seth Lederman, M.D., Chief Executive Officer of Tonix, stated, "TNX-801 has conferred protective immunity to animals with single-dose administration... We believe the potential of TNX-801 is supported by real world evidence based on the success of horsepox-like vaccines prior to 1900 in protecting against smallpox and containing smallpox outbreaks."
Preclinical Efficacy and Tolerability
Preclinical data indicates that a single dose of TNX-801 prevented clinical disease and lesions and decreased viral shedding in animals challenged with clade I monkeypox. These findings suggest that TNX-801 induces mucosal immunity and could potentially block forward transmission. Data also showed that TNX-801 is highly attenuated compared to 20th-century vaccinia vaccines in immunocompromised animals, with no spread to blood or tissues, even at high doses.
Addressing the Mpox Threat
The World Health Organization (WHO) has declared the recent upsurge of mpox in Africa a Public Health Emergency of International Concern. The clade I monkeypox virus, responsible for this outbreak, is associated with higher case fatality rates than the clade II mpox virus that caused the 2022 global outbreak. There is concern that the clade I strain may appear in the U.S.
Synthetic Biology and Vaccine Development
Tonix is also developing TNX-1800, a horsepox-based vaccine expressing the SARS-CoV-2 spike protein for protection against COVID-19. TNX-1800 has been selected by the NIH’s Project NextGen for clinical trials. "Evidenced by the second WHO declared PHEIC involving an mpox epidemic since 2022, viral diseases are rapidly evolving and our methods to developing effective vaccines must evolve just as rapidly. Synthetic biology is an important technology for vaccine development," said Dr. Lederman.
Manufacturing and Collaboration
Tonix has announced a collaboration with Bilthoven Biologics (Bbio), part of the Cyrus Poonawalla Group, to develop GMP manufacturing processes for TNX-801. This collaboration aims to ensure the vaccine can be manufactured at scale economically, with standard shipping and storage requirements.
