Phase 2 Study Results Show Psilocybin Reduces Depressive Symptoms in Adult Patients With Cancer


The investigators note that psilocybin’s effectiveness in treating depressive symptoms and the positive reception among patients with cancer are encouraging continued research.

Results from a phase 2 clinical trial indicate that psilocybin-assisted therapy may provide patients with cancer and major depressive disorder (MDD) a reduction in symptoms of MDD. Psilocybin, which is currently classified as a Schedule I drug—a drug that has no accepted medical use with a high potential for abuse—binds to a specific subtype of serotonin receptor in the brain to cause alterations to the user’s mood, cognition, and perception. It is currently not approved by the FDA for clinical use; however, research is exploring the use of psilocybin-assisted therapies for mental health conditions including anxiety, addiction, and post-traumatic stress disorder.1

The open-label phase 2 trial enrolled both patients with curable and non-curable cancer with MDD. A 25-mg dose of psilocybin was administered simultaneously to cohorts of 3 to 4 participants with both individual (4.25 hours in 1:1 therapist to patient ratio) and group therapeutic support (3.75 hours) before, during, and after administration. In addition, the investigators conducted interviews with participants on the psilocybin trial. Outcomes included the severity of depression, anxiety, pain, demoralization, and disability.2,3

The study results indicate that psilocybin-assisted therapy in group cohort administration is both safe and practical in patients with cancer who have MDD. Further, data suggest the efficacy of this approach in this population based on a robust reduction in depression severity scores from baseline to post-treatment of 19.1 (95% CI, 22.3 to -16.0; p < 0.0001) by week 8. Further, approximately 80% of participants had experienced a sustained response to the psilocybin treatment, of which 50% showed full remission of depressive symptoms at week 1; these results were then sustained for 8 weeks. Participants in the trial also noted they experienced an increased sense of safety and preparedness in the group setting in particular, as well as a sense of connection.2,3

“As an oncologist for many years, I experienced the frustration of not being able to provide cancer care that treats the whole person, not just the tumor,” said lead author Manish Agrawal, MD, Sunstone Therapies, in a press release. “This was a small open-label study and more research needs to be done, but the potential is significant and could have implications for helping millions of patients with cancer who are also struggling with the severe psychological impact of the disease.”1

There were no serious adverse events (AEs) related to psilocybin reported by patients, and treatment-related AEs, such as nausea and headaches, were mild in severity and were expected by the investigators. Further, no laboratory or electrocardiogram abnormalities and suicidality were reported.2

The study authors also emphasized the study findings regarding the therapeutic benefit experienced by patients while in a group setting, and that the connection to the group contributed to participants' experience and feelings of compassion for one another. In addition, the implementation of both individuals and group therapy sessions allowed the therapy to remain an introspective, intimate process while still adding a feeling of community.1

“As a hematologist and palliative care physician and researcher, it was profoundly moving and encouraging to witness the magnitude of participants’ improvement and the depth of their healing journey following their participation in the trial. Participants overwhelmingly expressed positive sentiments about their experience of psilocybin-assisted therapy while emphasizing the importance of the supportive, structured setting in which it took place,” said senior study author Yvan Beaussant, MD, MSc, Dana-Farber Cancer Institute, in the press release. “Many described an ongoing transformative impact on their lives and well-being more than two months after having received psilocybin, feeling better equipped to cope with cancer and, for some, end of life.”1


1. Wiley. Psychedelic psilocybin-assisted therapy reduces depressive symptoms in adults with cancer and depression. News release. December 18, 2023. Accessed December 21, 2023.

2. Agrawal M, Richards W, Beaussant Y, et al. Psilocybin-assisted group therapy in patients with cancer diagnosed with a major depressive disorder. Cancer. 2023; 1-10. doi:10.1002/cncr.35010

3. Beaussant Y, Tarbi E, Nigam K, et al. Acceptability of psilocybin-assisted group therapy in patients with cancer and major depressive disorder: qualitative analysis. Cancer. 2023; 1-11. doi:10.1002/cncr.35024

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