Compass Pathways Reports Six-Month Phase 3 Data for Psilocybin Drug in Resistant Depression

Compass Pathways said on July 7 that its second Phase 3 trial of COMP360, a synthetic formulation of psilocybin, showed a durable effect through 26 weeks in people with treatment-resistant depression (TRD), according to the company's announcement. The results come from Part B of the COMP006 trial and are company-reported; they have not been published in a journal.

In the 25 mg arm, 39% of participants achieved a clinically meaningful reduction of at least 25% on the MADRS depression rating scale by week 6, after two fixed doses of COMP360 given three weeks apart, and on average maintained that benefit through at least week 26, Compass said. The company compared that with 25% in its first Phase 3 trial, COMP005, in which patients received a single dose. Nearly 30% of participants who responded at week 6 later went into remission after retreatment during Part B, according to the release.

The trial

COMP006 is a randomised, double-blind study with 581 dosed participants in North America and Europe. It compares two fixed doses of 25 mg COMP360 with 10 mg and 1 mg doses (296, 142 and 143 participants respectively). Part A, which met its primary endpoint at week 6, was disclosed in February 2026; Part B stayed blinded through week 26, and an open-label Part C runs from week 26 to week 52. Separation between the 25 mg and 1 mg arms was maintained through the blinded Part B period, the company said.

Participants had current depressive episodes lasting on average more than three years and more than six lifetime depressive episodes, according to Compass.

On safety, the company said most treatment-emergent adverse events were transient and occurred mainly on the day of dosing. The most common were nausea, headache, anxiety and visual hallucination. Serious adverse events occurred in 6.3% of the 1 mg arm and 5.7% of the 25 mg arm over 26 weeks, Psychiatric Times reported.

"The COMP006 data further strengthens our robust clinical package for COMP360 and represents an important step toward completing our NDA submission," said Kabir Nath, chief executive officer of Compass Pathways.

Regulatory path

A rolling new drug application and initial review with the US Food and Drug Administration are under way, and Compass said final submission remains on track for the fourth quarter of 2026. The company anticipates launching COMP360 in the first half of 2027, subject to FDA approval and following rescheduling by the Drug Enforcement Administration.

COMP360 has breakthrough therapy designation from the FDA for TRD, according to Compass. The company, which is headquartered in London, also has a late-stage program in post-traumatic stress disorder.

Compass estimates that about 4 million people in the US with major depressive disorder live with TRD, which is broadly defined as an inadequate response to two or more appropriate courses of approved medications.