TNX 4800, a first-in-class, single-dose monoclonal antibody being developed as a seasonal prophylactic, akin to a ‘Lyme vaccine’, for the prevention of Lyme disease, has had in-licencing announced. Designed for springtime administration, TNX 4800 provides passive immunity against Borrelia burgdorferi, the causative agent of Lyme disease, offering protection throughout the United States tick season.1
TNX 4800, developed at UMass Chan Medical School, targets outer surface protein A (OspA) on the bacterial surface and is engineered for extended half-life. This partnership marks a significant advancement in vector-borne disease prevention, particularly as no FDA-approved vaccines or prophylactic options currently exist.1,2
A single dose to cover the tick season
TNX 4800 is being developed as a single subcutaneous injection, to be administered in the spring and provide protection throughout the entire United States tick season, which extends into the autumn. Unlike vaccine candidates that require multiple doses, this passive immunization approach delivers immediate antibody-mediated protection without relying on the host immune response.2
The antibody is engineered for extended half-life by modifying its crystallisable fragment (Fc) domain. These alterations were derived from the original mAb 2217, resulting in mAb 2217LS with prolonged serum persistence.2
Targeting Borrelia in the tick, not the human host
TNX 4800 works by binding to OspA on B. burgdorferi in the midgut of infected Ixodes ticks, thereby preventing the bacterium from maturing and migrating into the tick’s salivary glands. This mode of action blocks transmission before the pathogen can infect humans.2
In animal models, TNX 4800 has successfully interrupted the transmission cycle of multiple Borrelia genospecies. Notably, the therapy is effective even in the absence of a host-generated immune response, a significant advantage in populations with immunodeficiencies or contraindications to vaccination.2
Addressing an urgent unmet need
Lyme disease remains the most common vector-borne illness in the United States, with an estimated 500,000 cases annually and rising incidence in endemic regions such as the Northeast, Mid-Atlantic, and Upper Midwest.3
Despite decades of research, no FDA-approved vaccines or prophylactic therapies are currently available. TNX 4800 has the potential to fill this gap with a practical, once-per-season option for high-risk populations including outdoor workers, hikers, military personnel, and residents in endemic areas.
Tonix CEO Dr Seth Lederman commented: “Licensing TNX 4800 expands our infectious disease pipeline with a differentiated, single-dose approach that can protect through the entire tick season. We believe this programme could benefit millions of people in Lyme-endemic areas.”2
Safety profile and next steps
Initial studies have demonstrated that TNX 4800 is safe and well tolerated, with predictable pharmacokinetics.2 Tonix intends to advance the candidate into adaptive Phase II/III trials in preparation for submitting a Biologics Licensing Application (BLA) to the US Food and Drug Administration (FDA).
Dr Mark Klempner, Professor of Medicine at UMass Chan and developer of mAb 2217LS, stated: “TNX 4800 is a single-dose antibody that provides immediate immunity, a key advantage over vaccine approaches currently in development.”2
Tonix also emphasized the collaborative nature of the project, with academic and industry partners working to address a growing public health challenge.
Future outlook
If successful, TNX 4800 could represent the first-ever seasonal monoclonal antibody prophylaxis for Lyme disease. Its mechanism of pre-tick-bite action, favourable dosing schedule, and immediate protection profile position it as a transformational candidate in vector-borne disease prevention.
About Lyme disease5,6,7,8
In the United States, Borrelia burgdorferi transmitted by infected Ixodes ticks causes Lyme disease, most commonly in the Northeast, Mid‑Atlantic, and Upper Midwest. Typical early symptoms include erythema migraines, fever, headache, and fatigue; without timely antibiotic therapy, infection may spread to the joints, heart, and nervous system. Laboratory diagnosis relies on FDA‑cleared tests using a two‑step serologic algorithm.
Although most patients recover fully with antibiotics, about 5‑10% develop Post‑Treatment Lyme Disease Syndrome (PTLDS), characterized by persistent symptoms such as fatigue, musculoskeletal pain, and cognitive difficulties. PTLDS falls under what is termed Infection‑Associated Chronic Illness (IACI).
Further content in Vaccines
This content has been developed independently by Touch Medical Media for touchINFECTIOUS DISEASES.
Editor: Katey Gabrysch, Editorial Director.
Disclosures: touchINFECTIOUS DISEASES utilize AI as an editorial tool (ChatGPT (GPT-4o) [Large language model]. https://chat.openai.com/chat). The content was developed and edited by human editors. No fees or funding were associated with its publication.
Cite: TNX 4800: Prevention of Lyme disease through seasonal prophylaxis. touchINFECTIOUS DISEASES. 23 September 2025.
References
- UMass Med. UMass Chan licenses monoclonal antibody for seasonal prevention of Lyme disease to Tonix Pharmaceuticals. 2025. Available at: https://www.umassmed.edu/news/news-archives/2025/09/umass-chan-licenses-monoclonal-antibody-for-seasonal-prevention-of-lyme-disease-to-tonix-pharmaceuticals/ (accessed 23 September 2025).
- Centres for Disease Control and Prevention. Lyme disease data and surveillance. Available at: https://www.cdc.gov/lyme/datasurveillance/index.html
(accessed 18 September 2025). - Tonix Pharmaceuticals. Tonix in-licenses monoclonal antibody TNX 4800 for prevention of Lyme disease. Press release. Available at: https://ir.tonixpharma.com
(accessed 18 September 2025). - Contagion Live. Tonix announces new seasonal Lyme antibody TNX 4800. Available at: https://www.contagionlive.com
(accessed 18 September 2025). - CDC. Chronic Symptoms and Lyme Disease; 31 Jan 2025. Available at: https://www.cdc.gov/lyme/signs-symptoms/chronic-symptoms-and-lyme-disease.html
(accessed 18 September 2025). - Talbot N, et al. Lyme Disease and Post‑treatment Lyme Disease Syndrome. Cureus. 2023. 15(8):e43112. doi: 10.7759/cureus.43112
- CDC. Lyme Disease Surveillance and Data. Mar 2025. Available at: https://www.cdc.gov/lyme/data-research/facts-stats/index.html (accessed 18 September 2025).
- CDC. Treatment and Intervention for Lyme Disease. Aug 2024. Available at: https://www.cdc.gov/lyme/treatment/index.html (accessed 18 September 2025).
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