Medical cannabinoids and brain tumours – Interview with Dr Wai Liu
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Dr Wai Liu is a Senior Research Fellow at St George’s, University of London, who has been investigating medical cannabinoids and their potential anticancer properties.
Dr Liu led a small research group at St Bartholomew’s Hospital investigating the anticancer properties in 2001. Anecdotal evidence presented to him suggested that cannabis could improve the responses to some therapies in patients with cancer. This led to more research studying the anticancer effects of cannabidiol (better known as CBD) in a variety of cancer types used both alone and in combination with other treatment modalities.
According to the research at St George’s, cannabinoids – the active chemicals in cannabis – have been confirmed to contain anticancer properties and are the most beneficial when combined with chemotherapy drugs.
I caught up with Dr Liu at event on medical cannabinoids and brain tumours in London, organised by our Member Charity brainstrust, and asked him a few questions so we could bring some more useful information to our community on this topical subject.
Does the research point towards CBD needing THC (tetrahydrocannabinol – the psychoactive constituent of cannabis) element in order to be effective for brain tumours?
Dr Liu: This is not so clear. There is no doubt that in the lab, THC has anticancer action. In a similar way, CBD has too. Using the two together seems to result in good activity, but the level of action is not necessarily synergistic, thus I suspect the two compounds do not actually require each other to work effectively.
You suggested in your research that it will never be the case of CBD alone – brain tumour trials need to allow for multiple agents in combination (such as chemotherapy drugs) . which is so hard to design in terms of a trial. Is that correct?
Dr Liu: Depending on the questions asked, combination trials can be relatively straightforward. For example, if you test only two drugs – the arms of the trials may be something like Drug A without CBD and Drug A with CBD.
What clinical trials are currently taking place, any plans linked to brain tumours?
Dr Liu: Very few – an up-to-date list will be on the Clinical Trials website.
Are clinicians prescribing CBD as part of the treatment for brain tumours? What are the barriers for brain tumour patients accessing CBD?
Dr Liu: Some clinicians are prescribing CBD, but this would not be on the NHS and so would be quite expensive. Apart from this way, it can be difficult to get official CBD from doctors.
The fundamental barrier for patients is the lack of full clinical trials confirming activity in patients. Without this ‘badge’, clinicians will rarely prescribe something that has no official clinical value. Once the trials in the UK are completed, depending upon results, access will almost certainly improve.
We know that some clinicians are advocating for medical cannabinoids to be prescribed as a standard for brain tumour patients to treat headaches and seizures, as well any cancer-related side effects – are there plans to expand guidelines so patients can readily access medical cannabinoids?
Dr Liu: Not sure; but it seems sensible that a drug that can help should be made available to patients that could benefit from using it. I understand there has to be legislation to ensure safety, but time is of the essence!
We thank Dr Liu for his time and answering my questions.
The research priorities at our Centres of Excellence are based on finding ways to innovate new curative treatments for brain tumours which will likely have the best outcomes for patients.
We are not currently funding any research into cannabinoids but recognise that the use of these for the management of brain tumours is an important topic and we will continue to closely monitor the ongoing developments in this area, including contributing to governmental Inquiries and consultations where possible.
Keep coming back to our website for our latest blogs and news on this subject, and if you subscribe to our e-news and/or follow us on Facebook and Twitter you’ll hopefully never miss any of our updates.
Image credit: St George’s, University of London
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Cannabis is the dried preparation, or resinous extract, of the flowers or leaves of the cannabis plant, a member of the hemp family. It is an illegal drug in many countries, including the UK.
The parts of cannabis that are considered important for medical reasons are called cannabinoids. This is the name for the complex chemicals found in cannabis that are responsible for the effect cannabis has on the body. Two cannabinoids are of particular interest:
- THC – delta-9 tetrahydrocannabinol (responsible for the psycho-active and addictive effects of cannabis)
- CBD – cannabidiol
It’s important to make clear the difference between cannabis, cannabis oil and CBD oil.
Cannabis and cannabis oil
Cannabis and cannabis oil are classified as a class B drug in the UK, because they contain the component THC. It is illegal to possess or supply them. However, from 01 November 2018, cannabis-based products for medicinal use will be available in the UK in some circumstances only.
Only specialist doctors who are listed in the General Medical Council’s (GMC) specialist register will be able to prescribe cannabis-based products. They will only be prescribed when the specialist considers that the patient will benefit and when the patient has an unmet special clinical need that cannot be met by licensed products.
- Medicinal cannabis, therefore, will be prescribed on a case-by-case basis
- Patients will NOT be able to get cannabis-based products from their GP
- If you feel you might benefit from these products, speak to your consultant or healthcare team
- Administration by smoking remains prohibited.
(For more information, see our blog on cannabis-based medicinal products.)
CBD oil is different from cannabis oil, because it does not contain THC.
It is currently legal in the UK – as long as it has been produced from an EU approved strain of hemp and as long as it is marketed as a food supplement without any medicinal claims. You can buy it in many high street health food shops.
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What is the evidence for cannabis-based products in the treatment of brain tumours?
Treating the side-effects of a brain tumour
There’s now conclusive evidence for the use of cannabis and its products, such as cannabis oil and CBD oil, for other therapeutic purposes, i.e. pain relief and treating chemotherapy-induced nausea and vomiting.
As such, the cannabis-based drug, Nabilone, has a medical licence and can be legally prescribed for chemotherapy-induced nausea and vomiting.
Treating the brain tumour itself
Currently, the evidence that cannabis-based products can treat brain tumours themselves is limited.
There have been some promising pre-clinical trials in mice, in which THC, CBD and radiotherapy used together appeared to slow tumour growth. More research involving clinical trials in people needs to be done.
There have also been some positive results using a drug called Sativex (a combination of THC and CBD) alongside the chemotherapy drug temozolomide (TMZ). It was found that in people with recurrent glioblastoma, those treated with Sativex had a higher chance of longer survival time, compared to those who didn’t have the drug.
However, it was a small trial, on only 21 patients, to test the safety and effectiveness of using Sativex. The next stage will be to look at whether Sativex works better than standard treatment or whether it produces fewer side-effects. Although a large amount of progress has been made, it could be up to another five years before this drug is licensed for use in brain tumour patients.
How can I get cannabis-based products?
Speak to your healthcare team.
Apart from the special circumstances described earlier above, and the prescribing of Nabilone for chemotherapy-induced nausea and vomiting, it might be possible for Sativex to be accessed via off-label prescribing.
Off-label prescribing is where your doctor can prescribe a drug licenced for another condition, if they feel it would benefit you and there is no other licensed treatment or all licensed treatments have failed. Sativex is licensed for the treatment of spasticity (tightening of the muscles) in multiple sclerosis.
However, many doctors may be reluctant to prescribe off-label as the responsibility for the prescribing and any adverse effects, lies with them. Also the professional codes, ethics and prescribing policies of their hospital trust may prevent it. You can always speak to your doctor about this.
Some people affected by a brain tumour may decide to self-medicate with cannabis.
We would always recommend that any supplements, alternative or complementary treatments that you/your loved one wishes to use are discussed with your/their medical team. This is because it may, for example, interact with other medications, such as anti-epileptic medicines, steroids or chemotherapy.
It is important to be aware that you cannot be sure of the concentrations and ratios of THC and CBD in grown or street cannabis.
If you need someone to talk to or advice on where to get help, our Support and Information team is available by phone, email or live-chat.
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There’s conclusive evidence for the use of cannabis and its products, such as cannabis oil and CBD oil, for other therapeutic purposes.