In brief
- The phase 3 COMP006 trial, involving 581 people, shows that two doses of synthetic COMP360 psilocybin sustain improvements in treatment-resistant depression through week 26.
- In the 25 mg arm, 39% achieved a clinically relevant reduction on the MADRS scale by week 6, and nearly 30% of those who responded reached remission after a second round of dosing.
- Serious adverse effects hovered around 6% for both high and low doses, with no new safety signals; Compass Pathways, the company funding and conducting the trial, expects to finalize its FDA filing in the last quarter of 2026.
On July 7, the British company Compass Pathways released six-month data from COMP006, its second phase 3 trial of COMP360, a proprietary synthetic psilocybin for treatment-resistant depression. With 581 participants dosed across North America and Europe, the study confirms that the improvement observed within weeks of the session does not fade over time: it is maintained, on average, up to six months later.
Three doses, two sessions separated by three weeks
The design compared three arms: 25 mg (296 people), 10 mg (142), and 1 mg, the lowest dose, used as an active control (143). Each participant received two fixed doses of psilocybin separated by three weeks, accompanied by therapeutic support before and after the session, as dictated by the standard protocol for these types of trials. On average, participants had been in their current depressive episode for nearly four years and had tried several previous treatments without success, the typical profile for treatment-resistant depression.
39% improved early and nearly a third of responders reached remission
In the 25 mg arm, 39% achieved a reduction of at least 25% on the MADRS scale by week 6, and that benefit was sustained on average through week 26. The most striking part of the announcement is Part B of the trial: among those who had responded to the first round, nearly 30% reached remission (MADRS score of 12 or below) after a subsequent retreatment, suggesting that a second intervention can deepen the effect rather than simply maintaining it. Regarding safety, the most common adverse effects were nausea, headache, anxiety, and visual hallucinations, almost always limited to the day of dosing. Serious adverse effects were similar across arms—6.3% with 1 mg versus 5.7% with 25 mg over 26 weeks—indicating that the high dose does not trigger serious risks compared to the low dose.
What this implies
It is important to read these numbers in context: these are data announced by Compass Pathways itself in a corporate press release and a poster at the American Society of Clinical Psychopharmacology congress, not yet a peer-reviewed article, and the company is publicly traded with a direct interest in the outcome. Even so, the sample is one of the largest to date in psychedelic therapy for treatment-resistant depression, and the retreatment data point to something relevant for the design of future protocols: that the response is not fixed after the first session. The company plans to finalize its approval application with the FDA in the last quarter of 2026, with a commercial launch depending on both regulatory approval and the DEA rescheduling the substance out of Schedule I.
Source
- Compass Pathways. Compass Pathways Announces Six-Month Data from Second Phase 3 Trial Confirming Rapid and Durable Profile. Compass Pathways press release reproduced in full on Yahoo Finance, July 7, 2026.
Educational content written from a harm reduction perspective and with respect for individual freedom. It is not a substitute for advice from a healthcare professional and is not intended to encourage or condemn any drug use.
