Compass Pathways announced its Phase 3 trial (COMP005) of COMP360, a synthetic psilocybin formulation, met its primary endpoint for treatment-resistant depression (TRD). A single 25 mg dose reduced severity of depression symptoms by 3.6 points on the Montgomery-Åsberg Depression Rating Scale (MADRS) at six weeks compared to placebo, a statistically significant and clinically meaningful result[P<0.001][1](#l1)235.
The trial enrolled 258 participants with TRD, was randomized, double-blind and placebo-controlled, and is the largest-ever study of psilocybin for this condition13.
Safety data from the study were consistent with prior results, with no evidence of a clinically meaningful imbalance in suicidality between active and placebo groups23.
Despite the trial success, Compass Pathways’ stock plummeted by 36% in premarket trading on June 23, 2025, dropping from $4.63 to $2.96. Investors appeared disappointed by the modest effect size and possibly concerned about the prospects for regulatory or commercial success23.
Compass intends to discuss these results with the FDA and will release further 26-week data as the COMP005 and ongoing COMP006 trials progress12.
Sources:
1. https://ir.compasspathways.com/News--Events-/news/news-details/2025/Compass-Pathways-Successfully-Achieves-Primary-Endpoint-in-First-Phase-3-Trial-Evaluating-COMP360-Psilocybin-for-Treatment-Resistant-Depression/default.aspx
2. https://www.fiercebiotech.com/biotech/compass-points-psychedelic-therapys-phase-3-win-investors-unimpressed
3. https://www.statnews.com/2025/06/23/compass-pathways-psilocybin-depression-treatment-meets-trial-goal/
5. https://www.psychiatrictimes.com/view/comp360-psilocybin-for-treatment-resistant-depression-positive-phase-3-efficacy-data