Jonathan Lambert

On Friday, the fledgling field of psychedelic medicine suffered a major setback. The FDA declined to approve MDMA-assisted therapy for PTSD, instead asking the drugmaker Lykos Therapeutics to conduct another clinical trial to better show that the treatment is safe and effective.

Tomorrow, a Food and Drug Administration advisory committee will meet to discuss whether the United States should approve its first psychedelic drug. The fate of the treatment—MDMA-assisted therapy for post-traumatic stress disorder—will turn on how the FDA interprets data from two clinical trials that, on their face, are promising.