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# Definium's Second Phase 3 Win Sets Up GAD's First New Mechanism in Nineteen Years
- URL: https://bioweek.com/definiums-second-phase-3-win-sets-up-gads-first-new-mechanism-in-nineteen-years/
- Published: 2026-09-15T05:05:52.000Z
- Updated: 2026-09-15T05:05:52.000Z
- Description: Definium's Phase 3 Panorama study met its primary endpoint in generalized anxiety disorder with a 5.1-point HAM-A gap, testing whether an active 50 µg control and zero psychotherapy can clear the FDA hurdle that broke Lykos.
- Author: BioWeek
- Tags: Pipeline, Policy

Definium Therapeutics [announced](https://www.stocktitan.net/news/DFTX/definium-therapeutics-announces-positive-topline-results-from-phase-nj36j48dsdc3.html?ref=bioweek.com) on September 14, 2026 that Panorama (MM120-301), its second Phase 3 study of DT120 (lysergide tartrate) orally disintegrating tablet in generalized anxiety disorder, met its primary endpoint. DFTX, formerly MindMed and valued at about $5.2 billion, now has three positive Phase 3 readouts: Voyage in GAD in August 2026, Emerge in major depressive disorder in June 2026, and Panorama. DT120 holds FDA Breakthrough Therapy designation in both indications. A pre-NDA meeting is scheduled for the fourth quarter of 2026, with a filing expected in the first half of 2027.

That calendar matters because GAD has gone nearly two decades without a new chemical entity. Eli Lilly's Cymbalta (duloxetine) was [approved](https://investor.lilly.com/static-files/499f0aa3-281f-49f4-9655-049aae179593?ref=bioweek.com) for the indication in August 2007\. About 26 million U.S. adults live with GAD. Standard care still rests on daily SSRIs, SNRIs, and benzodiazepines, with delayed onset of several weeks, sexual dysfunction, weight gain, adherence failures, and dependency risk. A single-dose 5-HT2A partial agonist that moves anxiety scores within days would represent a genuine mechanism shift. The open question is whether Panorama's effect size, clinic burden, and blinding design can survive an agency that previously rejected a psychedelic application.

### A 5.1-point gap and a modest response rate

Panorama enrolled 245 adults aged 18 to 74 across about 32 U.S. centers with DSM-5-confirmed GAD and a baseline Hamilton Anxiety Rating Scale score of at least 20\. Mean baseline HAM-A was 28.3 in the 100 µg arm and 28.0 on placebo. Patients were randomized 2:1:2 to a single dose of DT120 ODT 100 µg (n=96), a 50 µg active control (n=52), or matching placebo ODT (n=97).

At week 12, the 100 µg arm posted a least-squares mean HAM-A change of -9.8 points versus -4.7 on placebo, an adjusted difference of -5.1 points (p < 0.0001) and a Cohen's d of 0.64\. Onset was rapid. On day 2, CGI-S showed an adjusted difference of -0.8 points (p < 0.0001). At week 1, HAM-A change was -9.8 versus -4.5, a -5.3-point gap (p < 0.0001). Week 12 CGI-S difference was -0.6 points (p < 0.0001). The statistical package is clean, yet clinical conversion remains selective. HAM-A response (at least 50% reduction) was 32% versus 14% (p < 0.05). Remission (HAM-A of 7 or below) was 15% versus 4% (p < 0.05). Mild or better status (HAM-A below 16) was 35% versus 17% (p < 0.01). Two-thirds of 100 µg patients were not responders at week 12, meaning the drug may complement rather than completely displace daily oral maintenance.

### The 50 µg arm as a regulatory safeguard

The FDA's 2023 [guidance](https://www.fda.gov/regulatory-information/search-fda-guidance-documents/psychedelic-drugs-considerations-clinical-investigations?ref=bioweek.com) on psychedelic trials highlighted functional unblinding as a core validity threat. In August 2024, the FDA issued a Complete Response Letter to Lykos Therapeutics after an advisory committee rejected MDMA-assisted therapy for PTSD, citing unblinding, confounding psychotherapy, and inconsistent monitoring. Definium designed Panorama specifically to address that precedent. The trial excluded in-study psychotherapy entirely. The 50 µg arm, while not powered for statistical significance, yielded placebo-adjusted HAM-A changes of -3.5 at week 4 and -3.6 at week 12, roughly 50% and 29% lower than the 100 µg effect. That biological gradient provides Definium with empirical evidence that the 100 µg signal reflects pharmacology rather than expectancy.

Clinic operations were standardized into a medical protocol. Patients were monitored on dosing day and evaluated hourly starting at hour 5 using an End-of-Session Checklist. Average time to discharge criteria was 6.2 hours (median 6.0), with 94% meeting criteria by hour 8\. Across more than 1,000 Phase 3 sessions through September 10, 2026, 97% reached discharge readiness by hour 8\. That profile fits within standard specialty outpatient scheduling, though commercial payers will weigh the logistics of half-day monitored chair time.

### Safety profile and acute perceptual events

DT120 was generally well tolerated, with no drug-related serious adverse events and no suicidality signal. Discontinuation rates were balanced: 10.4% on 100 µg, 11.5% on 50 µg, and 10.3% on placebo. Overall treatment-emergent adverse event rates reached 94.8% on 100 µg, 96.1% on 50 µg, and 62.9% on placebo. On dosing day, illusion occurred in 68% of 100 µg patients versus 61% on 50 µg; nausea occurred in 37% versus 26%; and headache was reported in 24% versus 28%. These perceptual effects are consistent with 5-HT2A agonism and underscore why inert placebos struggle to blind psychedelic studies.

The formulation utilizes Catalent's Zydis fast-dissolving tablet technology for sublingual absorption of lysergide tartrate to bypass hepatic first-pass metabolism. While intended to minimize gastrointestinal side effects, nausea still affected over a third of high-dose recipients, demonstrating that sublingual delivery modulates absorption without fully removing systemic effects.

With Panorama, Voyage, and Emerge completed, Definium enters its fourth-quarter pre-NDA meeting with three pivotal studies and Breakthrough Therapy designation. The regulatory evaluation will focus on whether a 0.64 effect size, a 32% response rate, and a six-hour monitoring window deliver an approvable alternative to duloxetine-era care. The 50 µg dose gradient and psychotherapy-free trial structure represent the company's direct answers to the Lykos precedent ahead of an anticipated 2027 filing.