BERKELEY HEIGHTS, N.J., Aug. 3, 2026
Tonix Pharmaceuticals Holding Corp. announced that it has received official Type C meeting minutes from the U.S. Food and Drug Administration (FDA) confirming alignment on the key elements of its planned adaptive Phase 2 clinical field study for TNX-4800, a long-acting human anti-OspA monoclonal antibody being developed to prevent Lyme disease in adults across the United States. The company expects to initiate the trial in the first quarter of 2027, pending FDA review of the final study protocol. Unlike vaccines that require multiple doses to stimulate an immune response, TNX-4800 is designed to provide rapid passive immunity within two days through direct administration of protective antibodies. The investigational therapy targets outer-surface protein A (OspA) on Borrelia burgdorferi, preventing transmission of the Lyme disease-causing bacteria from infected deer ticks before infection occurs. Tonix believes the novel biologic could address a significant unmet medical need, as there are currently no FDA-approved vaccines or prophylactic therapies available for Lyme disease in the U.S.
Adaptive Phase 2 Trial Designed to Evaluate Prevention of Lyme Disease
The planned randomized, placebo-controlled adaptive Phase 2 study will enroll approximately 3,300 adults living in Lyme-endemic regions of the United States who are at increased risk of exposure to infected deer ticks. Participants will be randomly assigned to receive either TNX-4800 450 mg administered subcutaneously or placebo, followed by a second dose approximately three months later. The study’s primary efficacy endpoint will evaluate prevention of Lyme disease through six months after the first dose, while a key secondary endpoint will assess protection through three months. Safety and tolerability will be monitored over a 52-week follow-up period. According to the company, most participant enrollment is expected during the 2028 Lyme disease season, although enrollment may extend into 2029 if disease incidence is lower than anticipated. Manufacturing of investigational product is progressing as planned to support clinical site delivery in early 2027.
TNX-4800 Offers a Novel Passive Immunity Approach
TNX-4800 is an engineered human monoclonal antibody with an extended serum half-life that delivers passive immunity by targeting OspA, a validated Lyme disease prevention target expressed on Borrelia burgdorferi within infected deer ticks. When a tick feeds on an individual who has received TNX-4800, the antibody is ingested by the tick and is designed to kill or block maturation of the bacteria within the tick’s midgut before transmission to humans can occur. Preclinical studies demonstrated that maintaining adequate antibody concentrations achieved approximately 95% protection against infection in non-human primates exposed to infected ticks. Unlike traditional vaccination strategies, TNX-4800 does not depend on the recipient’s immune system to generate antibodies and is expected to provide season-long protection with a two-dose annual regimen, potentially offering improved convenience, efficacy, and tolerability compared with vaccine candidates currently under development.
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FDA Alignment Advances Tonix’s Infectious Disease Pipeline
The FDA’s agreement on the adaptive study design represents an important regulatory milestone for Tonix Pharmaceuticals’ infectious disease portfolio and strengthens the company’s strategy to expand beyond its commercial central nervous system products. In addition to TNX-4800, Tonix is advancing multiple investigational therapies across infectious diseases, immunology, rare diseases, and central nervous system disorders, including TNX-801 for mpox and smallpox prevention, TNX-1500 for kidney transplant rejection, and TNX-2900 for Prader-Willi syndrome. With Lyme disease remaining the most common vector-borne illness in the United States and affecting millions of individuals living in tick-endemic regions, successful development of TNX-4800 could introduce a first-of-its-kind monoclonal antibody prophylactic capable of delivering rapid, long-lasting seasonal protection against Lyme disease.
Source: Tonix Pharmaceuticals press release
