Stage IV Solid Tumor Cancer

Phase II randomized controlled trial, followed by an open-label extension phase. In the main study, participants will receive either a single high-dose (25 mg) or low-dose (1 mg) of psilocybin in the context of Psilocybin-assisted Existential, Attachment and RelationaL (PEARL) therapy. Upon completion of main study, participants who received the low dose will be offered to receive a single high-dose of psilocybin (25 mg) in the context of PEARL therapy (Open label extension study).