An Open Label Study of Multiple Doses of Cannabidiol in the Prevention of Acute Graft-Versus-Host Disease (GVHD)

Inclusion Criteria: 1. Any malignant hematological disease in CR or Myelodysplastic Syndrome (MDS) 2. Age ≥ 18 years 3. Karnofsky Score (KS) ≥ 60% 4. HSCT-Comorbidity Index (HSCT-CI) score ≤ 3 5. No major organ dysfunction 6. Myeloablative or reduced intensity conditioning regimen 7. Matched (7/8 or 8/8) unrelated donor 8. Peripheral blood stem cell graft 9. Female subjects of childbearing potential must use a medically accepted method of contraception and must agree to continue use of this method for the duration of the study and for the follow-up time period. Acceptable methods of contraception include abstinence, barrier method with spermicide, intrauterine device (IUD), or steroidal contraceptive (oral, transdermal, implanted, and injected) in conjunction with a barrier method. 10. Male subjects with partners of childbearing potential must agree to use adequate contraception (barrier method or abstinence) during the study. 11. Subject's written informed consent Exclusion Criteria: 1. Malignant hematological disease other than MDS, not in CR 2. Myelofibrosis 3. Allogeneic transplantation from a matched or mismatched sibling donor 4. Cord blood transplantation 5. Positive serology for HIV 6. Serious psychiatric or psychological disorders 7. Any uncontrolled infection at time of registration 8. Active consumption of illicit drugs (such as: Crack cocaine, Heroin, Methamphetamines, Cocaine, Bath Salts, Amphetamines, Methadone, Benzodiazepine, Ecstasy) 9. Use of Cannabis and/or its derivatives fourteen days prior to HSCT and for the duration of study participation 10. Uncontrolled hepatitis B or active hepatitis C infection. 11. QTc\>450ms per Fridericia's correction and Impaired cardiac function or clinically significant cardiac diseases 12. Inadequate renal function defined as measured creatinine clearance \> 2.0 mg/dl 13. Liver enzymes: ALT and AST \> 3x upper limit of normal 14. Pregnancy or breastfeeding ((positive serum β-HCG 7 days before first dose) 15. Treatment with another investigational drug, biological agent, or device within 30 days of first dose, or investigational cell therapy within 6 months of first dose