Definium's LSD-based pill reduces depression symptoms in late-stage trial

Definium Therapeutics said on Monday that a single dose of its LSD-based experimental pill significantly reduced symptoms of major depression in patients in a late-stage trial.

The New York-based company said its drug, DT120, helped patients record significantly lower scores on a standard depression scale than those on placebo after six weeks, with an 8.1 point difference, meeting the trial's main goal.

Just one week after taking a single pill, patients showed improvement, scoring 14.2 points better than the placebo group, with gains of 7.3 points at 12 weeks, the company said.

Analysts at Jefferies said earlier this month in a client note that a 4 to 5 point placebo-adjusted improvement at week 6 with durable effects would mark a strong result.

DT120 belongs to a class of drugs known as classic psychedelics, which temporarily alter perception, mood, and thinking. The drug is a pharmaceutical formulation of lysergide, better known as LSD, and works by activating serotonin receptors in the brain.

In April, U.S. President Donald Trump signed an executive order directing federal agencies to speed up access to medical research and treatment based on psychedelic drugs as potential treatments for serious mental health conditions.

Definium's drug was generally well-tolerated, with 99% of adverse events, mild to moderate, occurring mainly on the day of dosing, and no serious safety issues or increase in suicidal thoughts were observed.

The trial enrolled 149 participants aged 18 to 74 years with major depressive disorder, a leading cause of disability, morbidity and mortality.

About 21 million adults in the U.S. have experienced at least one episode involving persistent feelings of sadness, loss of interest in regular activities, etc., according to the National Institutes of Health.

The company said the results bring it closer to an FDA submission, and it is running a second late-stage depression trial.

(Reporting by Kamal Choudhury in Bengaluru; Editing by Shinjini Ganguli)

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This story was originally published June 22, 2026 at 8:21 AM.