Results From a Long-Term Observational Follow-Up Study of a Single Dose of Psilocybin for a Treatment-Resistant Episode of Major Depressive Disorder

This one-year observational follow-up study (n=66) examined the long-term outcomes of psilocybin (25 mg, 10 mg, 1 mg; COMP360) in treatment-resistant depression (TRD). Median time to depressive relapse was longest in the 25 mg group (92 days) compared to 10 mg (83 days) and 1 mg (62 days), with most participants relapsing by week 12. A post hoc analysis of those entering the follow-up study (n=58) found a more pronounced difference, with the 25 mg group maintaining benefits for 189 days. Adverse events were minimal, with one case of mild suicidal ideation in the 1 mg group.

Abstract of Results From a Long-Term Observational Follow-Up Study of a Single Dose of Psilocybin for a Treatment-Resistant Episode of Major Depressive Disorder

“Background: The largest randomized study of psilocybin to date demonstrated the efficacy of COMP360 25 mg (Compass Pathways’ investigational proprietary pharmaceutical-grade synthesized psilocybin formulation) in participants with treatment-resistant depression (COMP 001), compared with 10 mg and 1 mg doses. Here, we report findings from COMP 004, a 52-week observational follow-up of patients from COMP 001 and COMP 003, a small open-label study of the coadministration of 25 mg COMP360 with continuing antidepressant treatment.

Methods: Adverse events (AEs) were collected over the full 52-week period. The primary efficacy endpoint was time to a prespecified depressive event over the 52 weeks following COMP360 administration in COMP 001 participants, presented as Kaplan-Meier estimates. A post hoc analysis included only participants that entered COMP 004. Data were collected from July 2020 to July 2022.

Results: Sixty-six participants entered COMP 004 (COMP 001, n = 58 [25 mg group n = 22, 10 mg group n = 19, 1 mg group n = 17]; COMP 003, n = 8). Few AEs were reported post-entry into COMP 004, with 1 AE of mild suicidal ideation in the 1 mg group deemed possibly related to study drug. For all COMP 001 patients (n = 233), median time to depressive event was greater for the 25 mg group (92 days) compared to the 10 mg (83 days) and 1 mg (62 days) groups, with the majority of participants having had a depressive event by Week 12 (25 mg n = 37/75, 10 mg n = 38/79, 1 mg n = 44/75). The post hoc supplementary analysis of those who enrolled in COMP 004 from COMP 001 exhibited the difference between groups more strikingly (25 mg, 189 days; 10 mg, 43 days; 1 mg, 21 days); however, only 10 participants experienced a depressive event post-COMP 004 enrollment (25 mg n = 6, 10 mg n = 3, 1 mg n = 1) from COMP 001 and none from COMP 003. At COMP 004 entry, the 1 mg group had the highest number of participants on antidepressant medication (n = 10; 10 mg, n = 9; 25 mg, n = 6) and generally initiated treatment earlier.

Conclusion: Over 52 weeks, a single administration of 25 mg psilocybin suggested longer maintenance of antidepressant effect than both 1 mg and 10 mg. Larger long-term studies are required to confirm these findings and provide clarity on the longer-term effects of psilocybin.“

Authors: Guy M. Goodwin, Ania Nowakowska, Merve Atli, Boadie W. Dunlop, David Feifel, David J. Hellerstein, Lindsey Marwood, Zainib Shabir, Sunil Mistry, Susan C. Stansfield, Emma Teoh, Joyce Tsai, Matthew B. Young & Ekaterina Malievskaia

Summary of Results From a Long-Term Observational Follow-Up Study of a Single Dose of Psilocybin for a Treatment-Resistant Episode of Major Depressive Disorder