Cannabidiol (CBD), a non-psychotropic ingredient of Cannabis sativa possesses potent anti-inflammatory and immunosuppressive properties. In a recent prospective phase II study (NCT01385124) 48 consecutive adult patients undergoing allogeneic hematopoietic cell transplantation were given CBD 300 mg/day starting 7 days before transplantation until day 30, on top of standard GVHD prophylaxis consisting of cyclosporine and a short course of methotrexate. There were no grade 3-4 toxicities attributed to CBD. None of the patients developed acute GVHD while consuming CBD. With a median follow-up of 16 months, the cumulative incidence rates of grade 2-4 and grade 3-4 acute GVHD by day 100 were 12.1% and 5%, respectively. Compared to 101 historical control subjects given standard GVHD prophylaxis, the hazard ratio of developing grade 2-4 acute GVHD among subjects treated with CBD plus standard GVHD prophylaxis was 0.3 (p=0.0002). Among patients surviving more than 100 days, the cumulative incidence of moderate-to-severe chronic GVHD at 12 and 18 months were 20% and 33%, respectively.

The aim of this study is to explore the safety and efficacy of extended use of CBD until day 100 in the prevention of acute and chronic GVHD.

Inclusion Criteria:

1. Acute leukemia in complete remission
2. Myeloablative conditioning
3. Matched or one antigen or allele mismatched sibling or unrelated donor

Exclusion Criteria:

1. History of psychosis
2. Bronchial asthma