Definium's DT120 Orally Disintegrating Tablet (Lysergide) Achieves Landmark Phase 3 Success in Generalized Anxiety Disorder
In late August 2026, Definium Therapeutics reported positive topline results from its Phase 3 Voyage trial evaluating DT120 ODT (lysergide orally disintegrating tablet) in adults with generalized anxiety disorder (GAD). DT120 ODT is a proprietary, pharmaceutically optimized formulation of lysergide D-tartrate incorporating Catalent's Zydis® orally disintegrating tablet technology. The drug previously received FDA Breakthrough Therapy Designation for GAD.
The Voyage trial is the first of two pivotal Phase 3 trials designed to support a potential New Drug Application (NDA) for DT120 ODT. The second Phase 3 study, Panorama, is scheduled to report topline results in September 2026.
Phase 3 Voyage Study Design and Key Efficacy Results
The Voyage trial was a multicenter, randomized, double-blind, placebo-controlled Phase 3 study that enrolled 214 adults across 35 sites in the United States with a DSM-5-confirmed diagnosis of GAD. Participants were randomized 1:1 to receive a single dose of DT120 ODT 100 µg or placebo, and were evaluated over a 12-week double-blind period (Part A) followed by a 40-week open-label extension (Part B).
- Primary Endpoint Met with High Significance: At Week 12, the primary endpoint of change from baseline in the Hamilton Anxiety Rating Scale (HAM-A) total score demonstrated a highly statistically significant and clinically meaningful benefit. Patients treated with DT120 ODT achieved a least-squares (LS) mean change of -11.6 points compared to -6.2 points for the placebo group.
- Double the Effect Size of Standard of Care: The placebo-adjusted difference was -5.4 points (P < 0.0001), representing an exceptionally strong Cohen's d effect size of 0.81. This effect size is more than double that of currently approved GAD treatments, such as benzodiazepines, buspirone, and selective serotonin reuptake inhibitors (SSRIs), which typically demonstrate effect sizes between 0.17 and 0.38.
- Rapid and Durable Onset: Statistical separation from placebo emerged as early as Day 2 (as measured by the Clinical Global Impressions-Severity Scale, CGI-S) and Week 1 (HAM-A improvement of -7.7 points over placebo). Efficacy was fully maintained through all assessed timepoints up to Week 12.
- Strong Response and Remission Rates: At Week 12, 43% of DT120-treated patients achieved a clinical response (defined as a ≥50% improvement in HAM-A) compared to 16% on placebo. Furthermore, 14% of patients in the DT120 arm achieved full clinical remission (HAM-A ≤7) compared to 4% in the placebo arm.
- Subgroup Consistency: Efficacy was consistent across all analyzed subgroups, including patients who had previously failed two or more standard GAD medications.
Safety, Tolerability, and Session Dynamics
- Favorable Safety Profile: No serious adverse events (SAEs) occurred in the DT120 ODT arm, and no suicidality signal or suicidal behavior was observed. Most treatment-emergent adverse events (TEAEs) were mild-to-moderate, with illusions (75% on dosing day) and nausea (38% on dosing day) being the most common. Crucially, almost all TEAEs resolved on the dosing day itself.
- Predictable and Manageable Session Duration: The average time for patients to clear the End of Session Checklist (EoSC) was 6.4 hours in the Voyage trial. More than half of the participants cleared the EoSC within 6 hours, and 92% cleared it by 8 hours. This predictable 5-to-8 hour window is highly favorable for translating the therapy into standard clinical practice.
Next Steps and Pipeline
Following the Voyage readout, Definium's near-term focus is the upcoming topline readout of its second Phase 3 GAD trial, Panorama, in September 2026. The Panorama trial is designed similarly to Voyage but includes a low-dose 50 µg arm to confound functional unblinding and further validate the drug's efficacy. Definium is also evaluating DT120 in major depressive disorder (MDD) with a Phase 3 (Ascend) trial readout planned for 2027.