Compass Pathways announced results from two studies of its psilocybin-based drug COMP360 in patients with treatment-resistant depression. In the COMP001 (phase 2b) study of 233 patients, a single dose of 25 mg of COMP360 resulted in a highly statistically significant decrease in depression after three weeks compared to the 1 mg dose (p<0.001), with an effect lasting up to 12 weeks. The 25 mg dose showed the steepest reduction in symptoms, while the 10 mg dose was ineffective. In an early phase 3 trial (COMP005), a single dose of COMP360 produced a mean decrease of 3.6 MADRS points versus placebo at 6 weeks, with no safety concerns. Study COMP004, a 52-week follow-up of 66 patients from COMP001 and COMP003, showed that the 25 mg dose of COMP360 maintained the antidepressant effect longer than the 1 mg and 10 mg doses, with a median time to depressive relapse of 92 days versus 83 and 62 days, respectively. Adverse effects were mostly mild to moderate, such as headache, nausea or fatigue, with the occurrence of suicidality in all groups. A pivotal phase 3 is underway as the largest randomized trial of psilocybin, with COMP005 data expected in Q2 2025 and COMP006 in H2 2026.[1][2][3][4][5]