By Sarah Sinclair (Cannabis Health) with additional reporting from Ben Stevens
Researchers say they are working to get two long-awaited NHS clinical trials underway to investigate the role of cannabis-based medicines in severe forms of epilepsy.
The first significant update on the trials—first promised in 2019 following a government review—comes almost six years on from the legalisation of medical cannabis in the UK.
Led by researchers at University College London and Great Ormond Street Hospital for Children NHS Foundation Trust (GOSH), the studies are expected to begin recruiting 500 patients in 2025.
The first proposed trial will investigate cannabis-based medicines for adults and children with epilepsies beginning in the first three years of life. The second will look at patients with genetic generalised epilepsies (GGE) that have not responded to standard treatment.
Patients at multiple NHS sites across the UK will be randomly assigned either CBD, a combination of CBD and THC, or a matched placebo. Researchers will study whether these medicines are safe and effective in reducing seizures, as well as whether they affect learning, sleep, behaviour, quality of life, stress and anxiety.
Co-Chief Investigator, Professor Finbar O’Callaghan, UCL Great Ormond Street Institute of Child Health and Honorary Consultant at GOSH, commented: “For patients with difficult-to-treat epilepsies, cannabis-based medicinal products are promising treatments, but it is essential that we have high-quality evidence from robust clinical trials to be sure they are effective and do not have harmful effects. Only with this evidence will we establish whether these medicines might have a place alongside existing anti-seizure medications.”
Findings from the trial could in future be used to enable products to be licensed by the MHRA, and then approved by the NHS, if shown to be clinically and cost effective.
Co-Chief Investigator Professor Helen Cross, Director at UCL Great Ormond Street Institute of Child Health and Honorary Consultant at GOSH, added: “We know there is huge interest in finding out whether these medicines work and are safe. It is important that they are tested rigorously in high-quality clinical trials. Properly conducted scientific research takes time to organise but this is an essential step on the pathway to establishing whether these medicines are safe and effective and could eventually enable products to be licensed by the MHRA.”
Concerns over the trial design
However, experts and patient advocates in the UK have warned that the trials may not provide the solutions many are hoping for.
In a damning post on LinkedIn, Business of Cannabis award winner Hannah Deacon and her colleague Professor Mike Barnes, one of the UK’s most experienced and respected private medical cannabis prescribers, say that it is ‘maddening to see’ these studies being championed as being a solution.
The pair raise a number of key issues with the study, the first and most obvious being that children who want to take part must first have an eight-week ‘washout period’, meaning they are unable to take any cannabinoid medication during this time.
“That’s really, really dangerous, and could cause death,” Ms Deacon said.
She added that the study will do nothing to help children who are already prescribed cannabis-based medication as it will only use CBD and THC isolates.
Ms Deacon and Prof Barnes, along with Varinder Kaur, recently co-authored a new publication, providing a comprehensive overview of nearly 100 clinical trials, real-world studies, and observational research on the role of CBMPs in epilepsy management.
Professor Barnes explained that while ‘there is nothing wrong’ with using CBD isolate, which we know works well for epilepsy and is widely prescribed via drugs like Jazz Pharmaceuticals’ Epidyolex, it fails to take into account the benefits of full-spectrum products.
“In my experience, you get a better response if you use a little bit… of THC in a full-spectrum product. In my view, comparing a CBD isolate with a CBD plus THC isolate is not likely to show any difference between the two… I think they’re likely to be the same.”
He added that the use of terpenes as a placebo is ‘to be blunt, daft’, as terpenes also have medical value, including anticonvulsant properties.
Should the study find no difference between CBD isolate and CBD with THC isolate, as Professor Barnes predicts, this will have a ‘negative impact in people’s eyes’.
“They’ve missed the point entirely, that actually, the full spectrum product is better than the isolate products. I’m sorry to say, it’s been designed by people who, frankly, don’t really know what they’re doing.”
The need for personalised medicines in epilepsy
Concerns around the reliance on randomised control trials (RCTs) in the treatment of rare epilepsies are echoed by the wider epilepsy community. Treatment-resistant epilepsy affects around 35,000 patients in the UK, equivalent to around a third of all epilepsy cases.
Charities have highlighted the need for ‘innovation’ and ‘personalised medicines’ to move away from a ‘one size fits all approach’.
Matt Hughes, Co-Founder and Director of Medcan Family Foundation, which is a member of the Rare Epilepsy Together group, explains: “No two children are identical to underlying triggers and how they display seizures. Children metabolise medications differently and thus have differing responses, this is true of cannabinoids also.
“For 40 years the figure of 30% who live with uncontrolled seizures has never fallen. There is now a call from across the epilepsy community for change, to look towards innovation, to fast-track medicines to those with an urgent unmet need. The reliance on the RCT and a trial and error approach has failed so many diagnosed with uncontrolled epilepsy.”
Hughes points out that by the time the four-year trials are complete, a decade will have passed since their inception in 2019, despite the urgent need for new treatment options for this patient group.
“Too many children are left suffering each day,” he adds.
“We need the government and regulators to look at cannabis through a new lens and form pathways to licensing botanical medicines whilst enabling access to build the evidence base. Similar models already exist for other rare diseases.”
Families failed by inadequate policies
Families from the campaign group, End Our Pain, which was instrumental in changing the law in 2018, expressed similar concerns about the proposed trials.
“While we welcome any progress, we are concerned that it focuses solely on randomised controlled trials that do not consider individualised dosing or whole plant preparations,” said a spokesperson on behalf of the affected families.
“Despite promises of trials for funded access, we now face another trial for a cannabis-based preparation with controlled dosing, which risks dangerous washouts of successful whole-plant treatments.”
Despite government promises to ‘prioritise children with severe drug-resistant epilepsy’ and ensure ‘equality of access’, families feel ‘blocked’ from accessing the [unlicensed] medications that their children continue to ‘thrive on’.
There are still fewer than five NHS prescriptions for unlicensed CBPMs, compared with 300,000 items prescribed privately between 2021-23. End Our Pain continues to advocate for NHS access to unlicensed cannabis-based medicines, which are costing families up to £2,000 a month to access privately.
“Since the legislative change, we have campaigned for observational trials using full-extract cannabis preparations to prove their safety and efficacy and expand NHS-funded access for other children, especially since many in the 2018 cohort have struggled with licensed isolates,” they continue.
“The reality is that private funding for our children, costing £2,000 a month, is unsustainable. We are currently seeking the same funded access to full-extract cannabis preparations granted to three children in 2018 by the Home Secretary. After six years, we feel let down by inadequate policies that have resulted in fewer than five people receiving NHS-funded access. The NHS’s commitment to equality of access is being ignored.”
