Two Doses of Psilocybin for the Treatment of MDD in Adults With Cancer

Inclusion Criteria: 1. Signed informed consent form (ICF) 2. 18 years of age or above at Screening (V1) 3. Currently meet criteria for MDD (single or recurrent episode as defined by the DSM-5; if single episode, duration of ≥ 3 months) based on medical records, clinical assessment, and documented completion of the Mini International Neuropsychiatric Interview, version 7.0.2 (MINI 7.0.2) 4. A diagnosis of a malignant neoplasm with a diagnostic code from C00 to C97 according to the ICD-10 5. MADRS score ≥ 20 at Screening (V1) 6. Is not currently taking any antidepressant and/or antipsychotic medications or medical cannabis at Screening (V1) 7. Able to complete all protocol-required assessment tools without any assistance or alteration to the copyrighted assessments, and to comply with all study visits 8. Has capacity to consent per judgement of the Investigator Exclusion Criteria: 1. Current or past history of schizophrenia, psychotic disorder, bipolar disorder, delusional disorder, paranoid personality disorder, schizoaffective disorder, or borderline personality disorder, as assessed by medical history and a structured clinical interview (MINI version 7.0.2) 2. Current (within the past year) alcohol or drug use disorder as defined by the DSM-5 (MINI 7.0.2) at Screening (V1) 3. Significant suicide risk defined by (1) suicidal ideation as endorsed on items 4 or 5 on the C-SSRS within the past year, at Screening, or at Baseline, or; (2) suicidal behaviors within the past year, or; (3) clinical assessment of significant suicidal risk during participant interview 4. Other personal circumstances or behavior judged to be incompatible with establishment of rapport or safe exposure to psilocybin 5. Women who are pregnant, nursing, or planning a pregnancy. Women and men of child-bearing potential and who are sexually active must agree to use an acceptable contraceptive method throughout their participation in the study. Women of child-bearing potential must have a negative urine pregnancy test at Screening (V1) and Baseline (V2) 6. Cardiovascular conditions: recent stroke (\< 1 year from signing of ICF), recent myocardial infarction (\< 1 year from signing of ICF), uncontrolled hypertension (blood pressure \> 140/90), or clinically significant arrhythmia within 1 year of signing the ICF 7. A marked prolongation of QT/QTc interval (e.g., repeated demonstration of a QTc interval \> 450 ms at screening 8. A history of additional risk factors for Torsade de Pointes (e.g., heart failure, hypokalemia, family history of long QT syndrome) 9. The use of concomitant medications that prolong the QT/QTc interval 10. Uncontrolled or insulin-dependent diabetes 11. Seizure disorder 12. Positive urine drug screen for illicit drugs or drugs of abuse at V1 and V2. Any positive urine drug test will be reviewed with participants to determine the pattern of use and eligibility will be determined at the Investigator's discretion in conjunction with the medical monitor 13. Current enrollment in any investigational drug or device study or participation in such within 30 days of Screening (V1) 14. Abnormal and clinically significant results on the physical examination, vital signs, ECG, or laboratory tests at Screening (V1) that in the Investigator's opinion may constitute a risk for an individual who is exposed to psilocybin. This includes a value of \< 50,000 platelets per cubic millimeter of blood, liver function tests three times the upper limit of normal, and creatine two times above the normal range. Clinically significant abnormal electrolytes or low hemoglobin (\< 8 g/L) should be corrected and rechecked prior to enrollment 15. Any other clinically significant cardiovascular, pulmonary, gastrointestinal, hepatic, renal, or any other major concurrent illness that, in the opinion of the Investigator, may interfere with the interpretation of the study results or constitute a health risk for the participant if they take part in the study 16. Use of psychedelics, including psilocybin but excluding medical marijuana, within the past 6 months and use of psychedelics or cannabis during the current episode of depression 17. Concurrent or recent chemotherapy or radiation therapy that impairs general level of physical functioning