COMPASS Pathways plc announced that new long-term efficacy data of investigational COMP360 psilocybin in cancer patients with major depressive disorder will be presented at the Annual Meeting of the American Society of Clinical Oncology (ASCO). More than half of the patients (16/28) treated with a single dose of 25mg COMP360 psilocybin with psychological support remained in remission from their depression at 18 months post administration. The investigator-initiated study, led by Manish Agrawal, MD, at Sunstone Therapies, is believed to be the longest study of psilocybin therapy ever conducted.

The trial was a phase 2, single-center, fixed-dose, open-label study in 30 patients with curable and incurable cancer and major depressive disorder. Patients were treated with a single dose of 25mg of COMP360 psilocybin, administered simultaneously in group cohorts of 3-4, with group and individual psychological support, and evaluated at 8 weeks and 18 months. Of 30 patients from the parent study, 28 were enrolled in the follow-up study.

Key results: 8/28 patients (64.2%) demonstrated sustained clinical response from baseline to 18 months follow-up, 16/28 patients (57.1%) demonstrated remission of depression at 18 months. The original phase 2 study conducted by Sunstone was completed in 2021 and results were published in JAMA colony in April 2023. COMP360 is COMPASS's investigational proprietary formulation of synthetic psilocybin, administered in conjunction with psychological support.

COMPASS is currently conducting a phase 3 clinical program of COMP360 psilocybin therapy in treatment-resistant depression (TRD), the largest of its kind ever conducted. This program follows positive results from COMPASS's phase 2b study published in the New England Journal of Medicine.