Company on track to initiate a randomized, double-blind, placebo-controlled, adaptive Phase 2 field study in the first half of 2027, pending FDA agreement

Phase 2 field study expected to test a two-dose regimen of TNX-4800 subcutaneous with an initial Spring dose followed by a Summer booster two months later; the primary endpoint is Lyme disease prevention for six months

TNX-4800 is expected to provide protection against Lyme disease within two days of the first dose for the peak of the U.S. Lyme season

BERKELEY HEIGHTS, N.J., April 29, 2026 (GLOBE NEWSWIRE) -- Tonix Pharmaceuticals Holding Corp. (NASDAQ:TNXP) ("Tonix" or the "Company"), a fully integrated, commercial biotechnology company, announced presentation of Phase 1 data and plans for an adaptive Phase 2 field study of TNX-4800 (formerly known as mAb 2217LS)1,2 for the prevention of Lyme disease in the U.S., at the 4th Annual Ticks and Tickborne Diseases Symposium. The Phase 2 study is expected to initiate in the first half of 2027, pending FDA agreement.

The Phase 1 study was conducted by a team at UMass Chan Medical School led by Mark S. Klempner, MD, Professor of Medicine at UMass Chan and an inventor of TNX-4800. The adaptive Phase 2 field study is being planned by Tonix, which licensed TNX-4800 from UMass Chan Medical School in 2025.

TNX-4800 is a long-acting bactericidal (or borreliacidal), human monoclonal antibody (mAb) that targets the outer surface protein A (OspA) of Borrelia burgdorferi, the spirochete bacteria that causes 99.9% of Lyme disease cases in the U.S.3,4 TNX-4800 was engineered to include a crystallizable fragment (Fc) domain that provides an extended half-life. Tonix is developing TNX-4800 for the prevention of Lyme disease during the U.S. tick season. There are currently no marketed U.S. Food and Drug Administration (FDA)-approved vaccines or prophylactics to protect against Lyme disease.