NEW YORK — September 8, 2026
Definium Therapeutics announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to DT120 lysergide orally disintegrating tablet (ODT) for major depressive disorder (MDD), following positive Phase 3 Emerge results. The designation represents the second FDA Breakthrough Therapy designation for the DT120 development program, following its earlier designation for generalized anxiety disorder (GAD). The regulatory milestone strengthens Definium’s development strategy for DT120 across major psychiatric indications and reflects the FDA’s recognition of preliminary clinical evidence indicating potential substantial improvement over available therapies. The company is developing DT120 as part of its broader strategy to advance new therapeutics intended to address significant unmet needs in psychiatric and neurological disorders.
Phase 3 Emerge Data Support DT120 Development in MDD
The Breakthrough Therapy designation was supported by positive results from the Phase 3 Emerge study, in which a single 100 µg dose of DT120 ODT produced an 8.1-point placebo-adjusted improvement in MADRS total score at Week 6 (p<0.0001). Definium reported that the treatment effect remained durable through Week 12, providing clinical support for continued development in MDD. The findings are particularly relevant in a treatment landscape where many patients do not achieve remission with first-line therapies and may experience delayed treatment effects, tolerability challenges and treatment switching. For Definium, the Phase 3 results and subsequent FDA designation provide an important regulatory development milestone as the company works toward advancing DT120 through late-stage development and potential future commercialization in MDD.
DT120 Uses Proprietary Orally Disintegrating Formulation
DT120 ODT is Definium’s proprietary pharmaceutical formulation of lysergide, an ergoline derivative and classic serotonergic psychedelic that acts as a partial agonist at serotonin 5-HT2A receptors. The formulation incorporates Catalent’s Zydis fast-dissolve ODT technology, which is designed to provide rapid dissolution and support faster absorption and onset while potentially improving bioavailability and reducing gastrointestinal side effects. Definium is developing DT120 for MDD, GAD and posttraumatic stress disorder (PTSD) while exploring additional potential applications in serious brain health disorders. The company is also pursuing a multi-layered intellectual property strategy covering the composition, formulation and methods of use of DT120 ODT. The combination of a proprietary formulation, clinical development program and expanding regulatory designations forms a key component of Definium’s strategy to build a differentiated psychedelic medicine franchise.
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Definium Expands DT120 Across Psychiatric Indications
The second Breakthrough Therapy designation broadens the regulatory profile of DT120 across two major psychiatric indications, reinforcing Definium’s strategy of developing a single proprietary platform across multiple areas of unmet need. The company’s focus is on translating clinical evidence around psychedelics into pharmaceutical products designed for controlled medical use, with DT120 serving as its lead development program. The MDD milestone follows the earlier FDA recognition in GAD and comes as Definium continues advancing its late-stage clinical strategy. With positive Phase 3 Emerge data, Breakthrough Therapy designations in both MDD and GAD, and ongoing development in PTSD, Definium is positioning DT120 as a potential next-generation treatment platform for serious psychiatric disorders.
Source: Definium Therapeutics press release
