Tonix Pharmaceuticals Holding Corp. 8-K

What Happened

• On December 29, 2025, Tonix Pharmaceuticals Holding Corp. (TNXP) announced program updates for its TNX-4800 product candidate for protection against Lyme disease and said it plans to meet with the U.S. Food and Drug Administration (FDA) in 2026 to explore Phase 2/3 development options. The company said it may have GMP investigational product available for testing early in 2027 and indicated a controlled human infection model using Borrelia-infected ticks could be a potential path to demonstrating efficacy.

Key Details

• TNX-4800 Phase 1 study: randomized, double-blind, sequential dose‑escalation; 44 subjects randomized, 41 completed; single subcutaneous dose at 0.5, 1.5, 5, or 10 mg/kg.
• Pharmacokinetics: drug exposure increased ~25-fold for a 20-fold dose increase; serum measurable at 24 hours; concentrations quantifiable >200 days in 80% at lowest dose and up to 350 days at doses ≥1.5 mg/kg; mean half-life 62–69 days; serum quantifiable up to 12 months in most subjects.
• Safety/immunogenicity: most adverse events were mild or moderate; anti-drug antibodies detected in <10% with no impact on PK; mean exposure in the 10 mg/kg cohort was <20% of highest rat toxicology exposures.
• Regulatory plan: company intends to meet FDA in 2026 to discuss Phase 2/3 options and the potential use of a controlled human infection model; GMP product possibly available early 2027.

Why It Matters

• The filing signals TNXP is moving from early human safety/PK data toward regulatory discussions about later-stage development for TNX-4800. The Phase 1 results reported a long half-life, extended serum detectability, low anti-drug antibody rates, and generally favorable tolerability—factors that may affect dosing, trial design and regulatory conversations.
• For investors, key upcoming milestones to watch are the 2026 FDA meeting outcome and the company’s ability to produce GMP material for testing in 2027. The company’s description of a potential controlled human infection model is a proposed regulatory pathway, not an approved plan, and further clinical and regulatory steps will be required.