Psilocybin - a strategy of rapid antidepressant response in depression comorbid with cancer, a randomized double-blind study with the possibility of entering an open extension. Clinical trial PSIKET_002CZE is focused on the study of the antidepressant effect of the natural alkaloid psilocybin in a population of patients with a depressive disorder that accompanies an oncological disease (comorbid depression). The effect is compared with control substances with acute short-term antidepressant action (with ketamine) and without antidepressant action (with midazolam).