Psilocybin for Major Depressive Disorder (MDD)

Overview

Approximately 240 eligible adult participants (≥18 years old) who meet Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR) criteria for Major Depressive Disorder (MDD) will be enrolled. Participants will be randomly assigned to receive a single oral dose of Psilocybin 25 mg, Psilocybin 5 mg, or inactive placebo. The purpose of this study is to evaluate the efficacy, safety, and tolerability of Psilocybin 25 mg versus placebo in adults with MDD, as assessed by the difference between groups in change in depressive symptoms from Baseline to Day 43 post-dose, and to characterize the durability of initial treatment effect and subsequent response to optional Psilocybin 25 mg re-administration(s) during the 1-year Follow-up Period.

Double-blind Period: Participants who show stable depression symptoms between Screening and Trial Baseline will be randomly assigned to receive a single oral dose of Psilocybin 25 mg, Psilocybin 5 mg, or inactive placebo. Investigational Product (IP) will be administered in the context of a "Set and Setting" (SaS) Protocol for psychosocial support, comprised of 1) a period of preparation with Facilitators prior to dosing; 2) administration of IP in an aesthetically pleasing room under the supervision of two Facilitators; and 3) post-dose integration sessions during which participants will discuss their dosing experience with the Facilitators. Trial outcome measures will assess depressive symptoms, functional disability, health-related quality of life, and clinical global impression of disease severity. Long-term Follow-up Period: After the initial 6-week Double-blind Period and completion of the post-dosing Trial Day 43 assessments, all participants will proceed into a 1-year Follow-up Period. During the 1-year Follow-up Period, participants will be followed regularly by clinic staff to assess MDD symptom severity, functional disability, and health-related quality of life; long-term safety data will also be collected. In addition to scheduled clinic visits, clinic staff will contact participants by telephone every two weeks to assess for changes in MDD symptom severity, concomitant medications, adverse events (AEs), and suicidal ideation and behavior. Participants who meet the pre-defined MDD severity criteria and meet all re-administration eligibility criteria may be offered re-administration(s) of open-label Psilocybin 25 mg administered under a "Set and Setting" (SaS) Protocol. Psychosocial support, including psychoeducation, is also incorporated in the long-term Follow-up Period.