Tonix Highlights Promising Preclinical Results For Single-Dose Mpox Vaccine TNX-801 At World Vaccine Congress 2025

Tonix Pharmaceuticals, a biopharmaceutical company, presented new preclinical data on its investigational mpox vaccine, TNX-801, during an oral session at the World Vaccine Congress Washington 2025. The study showed that TNX-801, a minimally replicative, live-virus vaccine based on synthetic horsepox, successfully protected animals against mpox and rabbitpox infections. Importantly, the vaccine was well tolerated, including in immunocompromised subjects, reinforcing its potential for broader use.

Seth Lederman, M.D., Chief Executive Officer of Tonix Pharmaceuticals, said, “TNX-801 shows promise as a potential mpox and smallpox vaccine by providing protective immunity to animals with a single dose. TNX-801 was generally well tolerated, even in immunocompromised animals. The new data show durable six-month protection against a lethal challenge with rabbitpox virus and protection of immunocompromised animals against a lethal challenge with monkeypox clade IIa virus. These new data build upon prior studies showing protection of animals against a lethal challenge with intratracheal clade Ia mpox virus. In all of these studies, after a single dose vaccination, TNX-801 prevented both clinical disease and formation of lesions.”

Dr. Lederman continued, “The ongoing clade IIb mpox epidemic that started in 2022 and the more recent and ongoing clade Ib mpox epidemic highlight the need for additional vaccine options, particularly single-dose options. Both the 2022 clade IIb and the 2024 clade Ib mpox epidemics have been declared by the World Health Organisation (WHO) as Public Health Emergencies of International Concern (PHEICs). We believe TNX-801 has the potential to make an impact towards preventing mpox and controlling future mpox epidemics.”

Unlike traditional vaccinia-based vaccines, TNX-801 offers a modern approach by providing single-dose, long-lasting immunity with better safety profiles. Its design aims to meet the current World Health Organisation (WHO) target product profile (TPP) for mpox vaccines. It emphasises easy administration, stability at room temperature, and effectiveness even in vulnerable populations.

Tonix had previously announced in September 2024 that TNX-801 aligns closely with the WHO’s draft TPP, which was outlined at the Mpox Research and Innovation Scientific Conference.