Definium's LSD-Based Pill Reduces Depression Symptoms in Late-Stage Trial

Jun 22, 2026

Definium Therapeutics reports its experimental LSD-based pill, DT120, significantly reduced symptoms of major depression in a late-stage trial. A single dose resulted in an 8.1-point greater improvement over placebo on a standard depression scale after six weeks. The drug was well-tolerated with no serious safety issues, moving it closer to a potential FDA submission amid growing interest in psychedelic treatments.

DT120 trial results

▪At 12 weeks, the placebo-adjusted improvement for patients on DT120 was 7.3 points.
▪The trial enrolled 149 participants aged 18 to 74 with major depressive disorder.
▪Six weeks after a single dose, patients taking DT120 had a 13.3-point drop on the MADRS depression scale, versus 5.2 points for placebo.
▪Following the announcement on June 22, 2026, Definium Therapeutics' shares rose over 25% in premarket trading.
▪The 8.1-point placebo-adjusted improvement on a standard depression scale at six weeks met the trial's main goal.
▪Definium Therapeutics announced its LSD-based pill, DT120, significantly reduced major depression symptoms in a late-stage trial.
▪Jefferies analysts previously noted that a 4 to 5 point placebo-adjusted improvement at week 6 would be a strong result.

LSD pharmaceutical formulation

▪The drug functions by activating serotonin receptors in the brain.
▪DT120 is classified as a classic psychedelic, a type of drug that temporarily alters perception, mood, and thinking.
▪DT120 is a pharmaceutical formulation of lysergide, commonly known as LSD.

Adverse events profile

▪The DT120 trial reported no serious safety issues or increase in suicidal thoughts.
▪In the trial, 99% of adverse events were mild to moderate and primarily occurred on the day of dosing.

Major depressive disorder prevalence

▪Major depressive disorder is a leading cause of disability, morbidity, and mortality.
▪Approximately 21 million adults in the U.S. have experienced at least one episode of major depression, according to the National Institutes of Health.

FDA submission timeline

▪In April, U.S. President Donald Trump signed an executive order to accelerate access to psychedelic drug research and treatment.
▪Definium Therapeutics is currently conducting a second late-stage trial of DT120 for depression.
▪The positive trial results bring Definium Therapeutics closer to a potential FDA submission.