Compass Pathways Will Lead Two Concurrent Phase 3 Trials On Psilocybin-Assisted Therapy For Depression

Psychedelics biotech company Compass Pathways CMPS announced it will conduct two separate Phase 3 clinical trials to study psilocybin-assisted therapy on Treatment-Resistant Depression (TRD), reported Microdose. 

Assuming positive results, Compass will work with the FDA to help legalize psilocybin for TRD treatment, possibly as early as 2025.

These studies will be the two largest psychedelic medicine clinical trials ever conducted, with 378 and 568 patients respectively.

The difference between the two Phase 3 studies is the smaller one will test a single psilocybin dose of 25 mg against the placebo, while the larger will test two repeated doses, at either 25 mg or 10 mg against a placebo. Reduction in depression symptoms will be measured through the MADRS test. 

COMP 005’s cohort group is already larger than Compass’ prior Phase 2b trial of 233 patients. The study will be 2:1 randomized, with 252 patients receiving proprietary psilocybin COMP360 combined with therapy, while the remaining 126 patients will be delivered the placebo together with therapy. All patients will undergo both preparation and integration therapy sessions. 

This trial’s total duration is set at six weeks, and topline results are expected by the end of 2024. The company expects to be able to determine whether they replicate the treatment response seen in the previous Phase 2b trial, and the treatment’s safety profile (compared to the placebo.)

On the other hand, each participant in COMP 006 will receive two repeated doses -of the same degree- over the course of six weeks, together with preparation and integration sessions. The 2:1:1 randomization translates to 284 patients receiving two doses of 25 mg, 142 two doses of 10 mg, and 142 the placebo (1 mg).

Through this second Phase 3 trial to deliver topline results by mid-2025, Compass expects to assess whether a second dose of psilocybin increases the number of responders or improves responses as seen in former Phase 2b trials and if two doses of 10 mg of psilocybin produce a meaningful response.

As Microdose writer, James Hallifax explained, potential new medicine must pass through at least two Phase 3 clinical trials in order to be considered for legalization. So, by running two studies of this kind at once, Compass is aiming to show that psilocybin-assisted therapy is safer and holds more efficacy than current treatments for treatment-resistant depression.

The company’s Phase 2b trial showed positive yet mixed results, as a notoriously high percentage of participants suffered some kind of adverse effect. Also, the number of patients who received a 25 mg psilocybin dose and saw their depression symptoms significantly drop decreased as weeks went by. This is part of the grounds upon which COMP 006 is based - testing to see if a second psilocybin dose can help sustain the positive outcomes.

Should results on both trials prove positive, Compass would next work with the FDA on the legalization of psilocybin for the treatment of TRD within the next few years.

Photo courtesy of Geralt on Pixabay.