COMPASS Pathways plc (Nasdaq: CMPS)  announced further results from its groundbreaking phase IIb clinical trial of COMP360 psilocybin therapy for treatment-resistant depression (TRD). Compass said that additional analyses of primary and secondary endpoints validated topline findings and provided more insights into safety data. The objective of the trial was to find the appropriate dose for a larger, pivotal phase III program, which COMPASS said it expects to begin in 2022.

The study investigated three doses of COMP360 psilocybin (1mg, 10mg, 25mg) in 233 patients with TRD. The results showed that a single 25mg dose of COMP360 demonstrated a highly statistically significant and clinically relevant reduction in depressive symptom severity after three weeks, with rapid and durable treatment response. The 25mg group vs the 1mg group showed a -6.6 difference on the MADRS* depression scale at week 3 (p<0.001). In the 25mg group, 36.7% (29 patients) showed response* at week 3 and 29.1% (23 patients) were in remission* at week 3. Furthermore, at the end of the trial at week 12, 24.1% (19 patients) were sustained responders*. Additional analyses of primary and secondary endpoints have supported these results.

Professor Guy Goodwin, Chief Medical Officer, COMPASS Pathways, said: “Our additional analyses underline the robustness of our findings that a single high dose of COMP360 psilocybin, given in conjunction with psychological support, led to a rapid and sustained response for many patients. This phase IIb study was designed to determine the optimal COMP360 dose for our phase III programme, evaluating safety and efficacy at the primary endpoint at week 3. Additionally, we observed consistent improvement in measures of anxiety, positive and negative affect, quality of life, daily functioning, cognition, and self-reported depression. We believe this could make a tremendous difference to patients suffering with treatment-resistant depression, who have few options available to them. Remember, a quarter of the 25mg group maintained response, as measured by the MADRS, at 12 weeks after a single administration with no other antidepressant medication. This finding in itself is unprecedented.”

Analyses of exploratory measures including anxiety, self-reported depression, positive and negative affect, and functioning, showed greater improvements for patients receiving a 25mg dose of COMP360 psilocybin compared with those receiving a 1mg dose after three weeks, both with psychological support. Further analysis is ongoing and full trial results will be submitted for publication in a peer-reviewed journal. The data will be reviewed with regulators early next year.

Sidney Zisook MD, Director of the University of California San Diego Residency Training Program, a Distinguished Professor of Psychiatry at UCSD, and a Principal Investigator on the trial, said, “Many of the participants in this study had suffered for years with severe and crippling depressive disorders despite multiple treatment trials with traditional antidepressant medications and therapies. To see so many experience a robust and sometimes persisting response – and a new, brighter, more positive attitude – during the course of the study, was immensely gratifying and hopeful.”