NCT07326124

Stratification and Treatment in Early Psychosis Study -ASSIST

Full Title: Cannabidiol Augmentation of Clozapine in Treatment Resistant Psychosis: a Double-blind, Randomised Controlled Trial

• Status: Not Yet Recruiting
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 250 (estimated)
• Sponsor: University of Oxford · Academic / Other
• Sex: All
• Age: 16 Years – 50 Years
• Healthy volunteers: Not accepted

Summary

The purpose of this trial is: * To investigate whether the response to clozapine treatment can be enhanced by adding cannabidiol (CBD), compared to placebo, in treatment resistant psychosis patients. * To confirm the safety of CBD in people with psychosis. The trial is a randomised, double-blind, placebo-controlled, multi-centre, international, clinical trial. Individuals with a diagnosis of treatment resistant psychosis in their illness who have had a suboptimal or no response to clozapine treatment will be recruited. These patients are randomised to treatment with oral CBD 500mg twice daily, or a matching placebo for 12 weeks, in addition to clozapine, which is standard care treatment for this population. By using a battery of clinical outcome assessments, the trial will assess several optional biomarkers to predict clinical outcomes and response to treatment with CBD. Biomarkers are being assessed as an exploratory outcome measure. Participants will be invited to provide additional blood samples, stool samples, and complete neuroimaging assessments.

Conditions

• Treatment Resistant Psychosis
• Psychosis

Interventions

Type	Name	Description
DRUG	CBD 100 mg/mL Oral Solution	Daily dose 1000mg, taken as 500mg (5ml) b.i.d for 6 weeks. For participants with a weight lower than 50 kg, the dose is to be adjusted to 20 mg/kg/day divided over 2 intakes of 10 mg/kg/day, for a period of 12 weeks
DRUG	Placeb	5ml b.i.d for 6 weeks; For participants with a weight lower than 50 kg, the dose is to be adjusted to 20 mg/kg/day divided over 2 intakes of 10 mg/kg/day, for a period of 12 weeks

Timeline

• Start date: 2026-06-01
• Primary completion: 2028-09-01
• Completion: 2029-09-01
• First posted: 2026-01-08
• Last updated: 2026-01-08

Locations

15 sites across 8 countries: Germany, Greece, Israel, Italy, Netherlands, Spain, Switzerland, United Kingdom