LSD-Based Drug Succeeds in Two Phase III Mental Health Trials

Millions of people struggling with anxiety and depression might soon have a faster path to relief, thanks to a breakthrough drug that just aced its second major clinical trial.

Definium Therapeutics announced that DT120, an orally dissolving medicine derived from LSD, succeeded in treating generalized anxiety disorder in a Phase III trial. This follows the company's June 2026 success treating major depressive disorder with the same drug.

The latest trial, called Voyage, tested a single dose of DT120 against placebo in patients with generalized anxiety disorder over 12 weeks. Patients taking DT120 saw their anxiety scores drop by an average of 11.6 points on the standard Hamilton Anxiety Rating Scale, compared to just 6.2 points for those taking placebo.

What's remarkable is how quickly the drug worked. Patients felt better as early as day two after treatment, and those benefits lasted throughout the entire 12-week study period. Current anxiety and depression medications typically require weeks of daily use before patients notice any improvement.

The drug was also well-tolerated. Side effects were generally mild to moderate and occurred mostly on the day patients took the medicine. Researchers found no new safety concerns during the trial.

Definium is now waiting for results from a second Phase III anxiety trial called Panorama, expected in September. If that trial also succeeds, the company could seek approval to bring DT120 to market.

The Ripple Effect

The success of DT120 represents part of a broader movement in mental health treatment. Medicines derived from psychedelic compounds like psilocybin, LSD, and DMT are all advancing through late-stage clinical trials for conditions including anxiety, depression, and treatment-resistant depression.

The U.S. government appears supportive of this new frontier. President Donald Trump signed an executive order giving expedited regulatory review to psychedelic medicines that receive breakthrough therapy designation or complete Phase III trials.

Dr. Keith Heinzerling, study investigator and chief scientific officer at TRIP Clinics, said the rapid onset of action makes DT120 particularly valuable for patients who can't wait weeks for traditional medications to take effect.

However, experts note that healthcare systems need to prepare for these new treatments. Unlike daily pills that patients take at home, psychedelic medicines often require long supervised treatment sessions, which could pose logistical challenges.

The current wave of psychedelic research reminds some experts of the 1950s golden age of brain medicine, driven by high effectiveness rates that traditional treatments struggle to match.

For people who haven't found relief with existing medications, or who need faster help during mental health crises, treatments like DT120 offer genuine hope that better options are finally within reach.