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Definium’s LSD-based drug lowers anxiety in second successful late-stage study

By Thomson Reuters Sep 14, 2026 | 6:01 AM

By Kamal Choudhury and Puyaan Singh

Sept 14 – Definium Therapeutics said on Monday its LSD-based treatment reduced symptoms of generalized anxiety disorder in a trial, giving the company ​a second successful late-stage study for the condition.

A single ‌100-microgram dose of DT120, a fast-dissolving tablet of lysergide, the chemical name for psychedelic drug LSD, reduced scores on an anxiety scale by 9.8 points after 12 weeks, compared with a 4.7-point decline for placebo, the company ‌said.

Regulatory ​and investor enthusiasm for psychedelic-based therapies has ⁠helped Definium shares nearly ⁠triple this year. Psychedelic drugs can temporarily alter perception, mood and thinking.

DT120 had also significantly reduced anxiety symptoms in the first trial, the company had said in August.

CEO Robert Barrow said ​that having two studies confirming efficacy of the drug will increase the chances of getting the nod as about a ⁠dozen programs have attempted approval for ⁠GAD and have failed.

Benefits appeared as early as ​the second day and were sustained through week 12, Definium said.

GAD, ​characterized by persistent and excessive worry that can interfere with ‌daily life, affects about 26 million U.S. adults and is commonly treated with antidepressants, anti-anxiety medicines and psychotherapy.

The 245 patients in the new trial received either 100 micrograms of DT120, a lower ⁠50-microgram dose or placebo. The lower-dose arm was added to mitigate functional unblinding, a limitation of clinical trials where participants can accurately guess ⁠treatment assignments due ‌to distinct side effects or unmistakable drug experiences.

Nonetheless, ⁠at both doses, patients were able to correctly ​guess ‌when they were assigned to drug rather than ​placebo, Barrow ⁠said.

Higher efficacy on the 100-microgram dose versus the 50 microgram one, “gives us obviously an easier discussion (with regulators),” he said.

Definium expects to file a marketing application with the U.S. Food and Drug Administration in the first half of 2027.

(Reporting by Puyaan Singh and Kamal Choudhury in Bengaluru; Editing ​by Sahal Muhammed)