Tonix enrolls first patient in Phase 2 depression trial of TNX-102 SL

Tonix Pharmaceuticals Holding Corp. announced on June 29, 2026 that the first participant was enrolled in HORIZON, a potentially pivotal Phase 2 study evaluating the company's TNX-102 SL 5.6 mg product candidate as a first-line monotherapy in adults with major depressive disorder.¹

HORIZON is a 6-week, randomized, double-blind, placebo-controlled Phase 2 study evaluating TNX-102 SL 5.6 mg as a first-line monotherapy in adults with MDD, with approximately 360 patients expected to enroll at approximately 30 sites across the United States.¹ Eligible participants are 18 years of age or older and currently experiencing a moderate to severe major depressive episode, and will receive TNX-102 SL 5.6 mg taken sublingually at bedtime or matching placebo.¹ The primary endpoint is change from baseline in MADRS total score at Week 6, with secondary endpoints including global impression scores, anxiety ratings, and measures of sleep quality and disturbance.¹

TNX-102 SL is currently FDA approved in the U.S. as a once-daily bedtime treatment for fibromyalgia in adults under the brand name TONMYA.¹ The MDD study is separate from that approved use. The compound is a sublingual tablet formulation of cyclobenzaprine hydrochloride, designed for rapid transmucosal absorption, and acts as a tertiary amine tricyclic agent with antagonist activity at four receptor types: 5-HT2A serotonergic, alpha1-adrenergic, H1-histaminergic, and M1-muscarinic.¹

Beyond MDD, TNX-102 SL is also in development for acute stress disorder/acute stress reaction under an investigator-initiated IND, and Tonix holds additional active INDs for Long COVID, PTSD, alcohol use disorder, and agitation in Alzheimer's disease.¹ The company noted that the potential use of TNX-102 SL in MDD, ASD/ASR, and other unapproved indications remains under clinical development, and safety and efficacy have not been evaluated by any regulatory authority.¹