Harnessing monoclonal antibody technology: TNX-4800 for Lyme disease prevention
A human monoclonal antibody for the prevention of Lyme disease, discovered and developed at UMass Chan Medical School (MA, USA), was well tolerated in a recent Phase I trial, demonstrating lasting serum concentrations in participants. Mark Klempner presented the trial results at the World Vaccine Congress 2026 (30 March–2 April 2026; DC, USA). Pending FDA clearance, an adaptive Phase II field study is expected to begin in the first half of 2027. TNX-4800 offers an alternative to vaccine-based treatments, which can sometimes take up to 6 months to provide protection.
Lyme disease, the most common tick-borne illness in the Northern hemisphere, affects ~450,000 people annually in the US. It is a bacterial infection transmitted to humans via bites from ticks and can lead to serious joint, heart and nervous system issues if not treated promptly with antibiotics.
The team at UMass Chan Medical School discovered and developed TNX-4800, a new human monoclonal antibody that targets the bacterium Borrelia burgdorferi. The antibody works by blocking the maturation of B. burgdorferi in the mid-gut of infected ticks, effectively inactivating it before it reaches the skin at the site of the tick bite. In the Phase I trial, TNX-4800 was well tolerated and maintained lasting serum concentrations in participants.
“Our study demonstrated potentially protective blood levels of TNX-4800 at 2 days, with protective blood levels sustained for at least 4 months due to its extended half-life design,” explained Klempner, Professor of Medicine at UMass Chan Medical School. “Additionally, with its differentiated mechanism of action, TNX-4800 has the potential to provide passive immunity by directly supplying neutralizing antibodies, bypassing the need for a vaccine to induce a patient’s immune system to generate its own antibodies, which can be associated with other issues. We look forward to further clinical investigation of TNX-4800 as we strive to overcome this major public health challenge.”
Designed to be administered in the early spring before ticks are at their most active, TNX-4800 is expected to provide near-immediate protection against B. burgdorferi-caused Lyme disease. A single injection is formulated to maintain protective antibody serum concentrations for ~4 months, offering pre-exposure protection without relying on the recipient’s immune system to generate antibodies.
“TNX-4800 is expected to provide a preventative option to the 87 million people in the United States who are at high risk of contracting the disease because they live, work or vacation in a tick-endemic area,” commented Seth Lederman, CEO of Tonix Pharmaceuticals (NJ, USA), the commercial biotechnology company to which TNX-4800 was licensed.
“As a monoclonal antibody, we believe TNX-4800 offers significant advantages over vaccines in development. Lyme disease vaccines that elicit antibodies to OspA (a protein found on the outer membrane of the bacterium that causes Lyme disease) that are currently in development take more than 6 months to offer protection and require complex immunization schedules. A previously approved anti-OspA vaccine was withdrawn due to poor uptake, potentially relating to its complex immunization schedule,” continued Lederman.
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The Phase I study primarily aimed to evaluate the safety and tolerability of a subcutaneous injection of TNX-4800 in healthy male and female subjects aged 19–65, with a secondary objective to evaluate pharmacokinetics. A total of 44 subjects were enrolled in the study, with 41 completing it. Results indicated no significant clinical or laboratory safety concerns, with most adverse events being marked as mild or moderate.
Pending FDA clearance, Tonix Pharmaceuticals plans to initiate a randomized, double-blind, placebo-controlled, adaptive Phase II trial in the first half of 2027.
