F.D.A. Declines to Approve MDMA Therapy, Seeking More Study

The agency said there was insufficient data to allow the use of a treatment for PTSD that involves the drug known as Ecstasy.

The Food and Drug Administration on Friday declined to approve MDMA-assisted therapy for the treatment of post-traumatic stress disorder, dealing a serious blow to the nascent field of psychedelic medicine and dashing the hopes of many Americans who are desperate for new treatments.

The F.D.A. said there was insufficient data to allow its use, and it asked the company seeking approval for the treatment, Lykos Therapeutics, to conduct an additional clinical trial to assess whether the drug, commonly known as Ecstasy or molly, would be safe and effective.

An additional clinical trial could add years, and millions of dollars, to the approval process.

If approved, MDMA would have become the first psychedelic compound to be regulated by federal health authorities. Supporters of psychedelic medicine were deeply disappointed, and some said they were stunned, having assumed the therapy’s promising data would overcome flaws in the company’s clinical trials, which had been designed in consultation with F.D.A. scientists.

“This is an earthquake for those in the field who thought F.D.A. approval would be a cinch,” said Michael Pollan, the best-selling author and co-founder of the UC Berkeley Center for the Science of Psychedelics. His book, “How to Change Your Mind,” helped catalyze public interest in the therapeutic potential of psychoactive compounds, demonized during the nation’s long war on drugs.

But the agency’s decision had not been entirely unexpected, after a group of independent experts convened by the F.D.A. to evaluate Lykos’s data met in June and did not recommend the treatment. On two central questions, the experts voted overwhelmingly that the company had not proven the treatment was effective, and that the drug therapy’s benefits did not outweigh the risks.