New Study Says Patients May Stay on Depression Meds While Taking Psilocybin Therapy

Compass is now moving forward with a larger phase 3 clinical program, marking the most extensive study of its kind to date.

Compass Pathways (Nasdaq: CMPS) has revealed positive results from a phase 2 clinical trial investigating the use of its synthetic psilocybin treatment, COMP360, alongside daily SSRI antidepressants in treating persistent depression, the company announced Monday.

The study explored the efficacy and safety of a single 25mg dose of synthetic psilocybin combined with psychological support and an SSRI, given to 19 individuals dealing with treatment-resistant depression. The results were initially disclosed in December 2021.

Now, the company announced that data from the trial has been published online in the esteemed Nature Journal, Neuropsychopharmacology.

42% of participants in the study exhibited a significant reduction in their depression severity, achieving response and remission rates at the three-week mark. These promising findings closely mirror the results from Compass’ previous phase 2b study in which patients were taken off antidepressants before receiving COMP360.

“It has long been thought that SSRIs could interfere with the potential therapeutic effect of psilocybin,” Guy Goodwin, chief medical officer at Compass Pathways said in a statement.

“This data is exciting because it provides a preliminary signal that this is not the case and that patients could remain on their SSRI antidepressant medication and experience the same effect from COMP360 psilocybin treatment as people who are not on SSRIs.”

Goodwin also stated that these results could provide important clinical options for patients if COMP360 receives regulatory approval for the treatment of persistent depression.

COMP360, the firm’s proprietary version of synthetic psilocybin, is administered alongside psychological support. Following the results of its phase 2b trial, Compass is now moving forward with a larger phase 3 clinical program, marking the most extensive study of its kind to date.

The clinical firm has long pitched that patients and healthcare providers would see more progress in legal psychedelic-based medicine materialize from the outcome of this program, which could potentially provide new avenues of treatment for those suffering from persistent depression.

Hercules Capital recently put $50 million behind the venture, which more than half was already drawn at the end of June.

The peer-reviewed article concluded:

This study found that a single, open-label administration of psilocybin 25 mg led to an acceptable experience for participants with TRD when administrated adjunct to an SSRI and supports further development of psilocybin with psychological support for people with TRD. This study demonstrated the feasibility of simultaneous psilocybin administration to multiple participants as previously reported [1, 52], provided that adequate support is available. This design could reduce resource requirements for administration and provide a more accessible option for future research or in clinical practice. These encouraging results suggest that further investigation of psilocybin adjunct to antidepressant drugs would be valuable, especially in cases where antidepressant drug withdrawal may not be desirable.

Adam Jackson

Adam Jackson writes about the cannabis industry for the Green Market Report. He previously covered the Missouri Statehouse for the Columbia Missourian and has written for the Missouri Independent. He most recently covered retail, restaurants and other consumer companies for Bloomberg Business News. You can find him on Twitter at @adam_sjackson and email him at

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