The Food and Drug Administration (FDA) has declined to approve the psychedelic drug MDMA for treating post-traumatic stress disorder (PTSD), citing significant limitations in the submitted data and requesting an additional late-stage clinical trial. This decision is a major setback for Lykos Therapeutics and the broader movement to incorporate psychedelics into mainstream mental health treatments. Lykos' CEO, Amy Emerson, expressed deep disappointment, highlighting that conducting another phase 3 trial would take several years. The FDA's ruling follows an advisory committee's earlier recommendation against approval, raising concerns about study design, safety, and efficacy. Despite the setback, experts believe that psychedelic therapies still hold promise for future FDA approval.