Psilocybin-Assisted Psychotherapy for Anxiety in People With Stage IV Melanoma

This study is to find out about whether two sessions of psilocybin-assisted psychotherapy are safe and will help people who are anxious as a result of having stage IV melanoma and will involve two sessions of psychotherapy combined with either 4 or 25 mg psilocybin. The study will measure anxiety, depression, quality of life and spirituality before and after psilocybin-assisted psychotherapy, natural killer cells (a type of immune cell) will be counted from blood samples taken the day after psilocybin-assisted psychotherapy, and people will keep daily diaries reporting on how anxious they feel for each day in the study.