Ketamine-assisted Psychotherapy (KAP) for Patients With Existential Distress Associated With Non-operable GI Cancers

Inclusion Criteria: * Participant aged ≥ 18 years. * Participant with non-operable GI cancers requiring multi-modal treatment (e.g. surgery +/- chemo +/-radiation) and have a a high likelihood of recurrence and/or treatment failure in the opinion of the treating investigator. * Screen positivity for existential distress on the EDS, defined as scoring ≥ 3 on any of the 10 component domains, or a total score ≥ 6 * ECOG Performance Status ≤ 2. * Adequate hepatic function as defined as: * Total Bilirubin ≤ 1.5x institutional upper limit of normal (ULN) unless elevated bilirubin is related to Gilbert's Syndrome * AST(SGOT)/ALT(SGPT) ≤ 3 × institutional ULN * Subjects with liver metastases will be allowed to enroll with AST and ALT levels ≤ 5 x ULN. * For participants of childbearing potential: Negative pregnancy test or evidence of post-menopausal status. The post-menopausal status will be defined as having been amenorrheic for 12 months without an alternative medical cause. The following age-specific requirements apply: * Participants \< 50 years of age: * Amenorrheic for ≥ 12 months following cessation of exogenous hormonal treatments; and * Luteinizing hormone and follicle-stimulating hormone levels in the post-menopausal range for the institution; or * Underwent surgical sterilization (bilateral oophorectomy or hysterectomy). * Participants ≥ 50 years of age: * Amenorrheic for 12 months or more following cessation of all exogenous hormonal tre…