Lack of Evidence a 'Major Hurdle' to Cannabis-based Medicines

Peter Russell

August 09, 2019

A lack of good quality randomised control trial data was a "major hurdle" to NHS patients being able to obtain cannabis-based products for medicinal use (CBPMs), an NHS England review found.

The report, Barriers to accessing cannabis-based products for medicinal use on NHS prescription , said the evidence gap was particularly stark in the case of products containing delta-9-tetrahydrocannabinol (THC), making it unlikely that trusts would sanction their prescription.

In contrast, due to better quality data for products containing cannabidiol (CBD), clinicians were more willing to prescribe these for some conditions, the report found.

Overall, however, clinicians interviewed for the review said more robust evidence demonstrating adequate safety of CBPMs, and information on their clinical cost-effectiveness, were needed.

'Major Gaps' in Research

The report aimed to address some of the concerns expressed by patients and clinicians since the law was changed in November 2018 to allow specialist doctors to prescribe cannabis-based medicines.

The new rules followed high profile cases, including young epilepsy patients Alfie Dingley and Billy Caldwell, whose conditions appeared to be eased by CBPMs.

However, many patients with conditions including multiple sclerosis (MS) and epilepsy have been frustrated that they are still unable to access the treatments.

Last month, the House of Commons Health and Social Care Committee identified "major gaps" in research into CBPMs.

MPs said that few prescriptions had been issued since the law was changed because most medicinal cannabis products were not licenced or approved. The report called on the Government and the pharmaceutical industry to ensure that clinical trials of CBPMs went ahead.

The NHS Review

The NHS review recommended that research into the efficacy of CBPMs is prioritised. This should include research into five priority areas identified by the National Institute for Health and Care Excellence (NICE). These were:

  • CBD as an add on treatment for adult patients with Fibromyalgia or persistent treatment-resistant neuropathic pain

  • CBPMs for Chronic pain in children and young people

  • CBPMs for people with spasticity

  • CBD for severe treatment-resistant epilepsy in children, young people, and adults

  • The effect of adding THC to CBD on seizure frequency, brain structure and neurophysiological performance when compared with both CBD alone and placebo

The report also recommended that evidence was collected beyond the usual gold standard of randomised control trials, specifically in the case of children and young adults currently in receipt of a CBPM.

The NHS England report also addresses other issues, including ensuring that clinicians could have confidence in the quality of CBPMs supplied.

Dr Keith Ridge, chief pharmaceutical officer at NHS England said: "Without sufficient evidence to help them balance potential benefits against potential harms when they are deciding whether to prescribe medicinal cannabis to children with very severe epilepsy, it is clear clinicians are very reluctant to prescribe.

"We heard loud and clear the concerns and frustration the children's families are feeling, but these recommendations aim to help us develop the evidence base to understand how safe these products are, and ensure education and expert advice is available to support clinicians across the UK."

Commenting on the review for the Science Media Centre, Ian Hamilton, lecturer in mental health at the University of York, said: "The report makes clear that the policy change in November in effect raised expectations of patients but systems were not in place to meet these expectations; in effect it is only in recent months that the information that clinicians need to make decisions on whether to prescribe a product or not are being put in place.

"Although the report recognises that the cost of these products is a barrier to some patients and their health trusts, there are no potential solutions offered to mitigate this concern."

NICE Guidance

Meanwhile, NICE issued draft guidance on CBMPs. It did not recommend the use of an oromucosal spray containing CBD and THC (Sativex, GW Pharma or Bayer) for treating spasticity in people with multiple sclerosis because, despite evidence of benefit, it was not cost-effective at its list price. 

It also said that other cannabis-based medicinal products should not be offered to treat spasticity unless as part of a clinical trial.

The synthetic THC-mimic nabilone (Brown & Burk UK Ltd) was however recommended as an add-on for treating symptoms of nausea and vomiting in adults having chemotherapy where symptoms had not responded to conventional licensed medicines.

An appraisal committee said it was unable to make a recommendation about the use of CBMPs for severe treatment-resistant epilepsy because of a lack of clear evidence that they worked.

The guidance also said that, apart from CBD, used on its own in the context of a clinical trial, CBMPs were not cost-effective for treating chronic pain.

Paul Chrisp, director of the Centre for Guidelines at NICE, said: "We recognise that some people will be disappointed that we have not been able to recommend the wider use of cannabis-based medicinal products. However, we were concerned when we began developing this guidance that a robust evidence base for these mostly unlicensed products was probably lacking.

"Having now considered all the available evidence it's therefore not surprising that the committee has not been able to make many positive recommendations about their use.

"In most cases, the draft guidance recommends that more research is carried out, echoing the recent call by the National Institute of Health Research for research proposals for these products.

"To that end NICE welcomes the recent suggestion from the House of Commons Health and Social Care Committee that companies should be encouraged to undertake or enable research into their medicinal cannabis products."

'Bitterly Disappointed'

The MS Society said it was "bitterly disappointed" by the draft guidance. Genevieve Edwards, director of external affairs, commented:  "MS is relentless, painful, and disabling, and yet not a single person with MS has benefited from medicinal cannabis being legalised 9 months ago.

"The Government and the companies behind Sativex need to make people with MS a priority. Together with NICE, they must get around the table immediately to make Sativex available. This depends on the manufacturers accepting a lower price for the medicine, as right now the cost is entirely unrealistic."

Epilepsy Action said the prospect of patients having to wait many years for trials to be completed was "unacceptable".

Simon Wigglesworth, deputy chief executive, said: "We have always been clear about the need for more good quality clinical evidence. However, there remains a compelling argument that patients who could benefit from cannabis-based medicines should be given the opportunity to access them as a last-line treatment, where some evidence of potential benefit exists."

Consultation on the NICE draft guidance runs until 5th September 2019.


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