In this blog post I’d like to give a laypersons summary of a presentation I attended on Cannabis and Cancer. It was one of St. George’s, University of London ‘spotlight on science’ series of presentations, designed to engage the public in science.
Dr. Wai Liu, who’s work focuses on developing novel approaches against cancer, including cannabis compounds and their potential anti-cancer properties, headed up the presentation with input from his colleagues, including the eminent Professor of Oncology Angus Dalgelish.
The presentation started off with an overview of what cancer is, the mechanisms involved and what controls cell growth before moving on to an introduction to immunotherapy. There was then an introduction to cannabis, in particular Tetrahydrocannabinol (THC) and Cannabidiol (CBD), which was followed by a specific focus on CBD.
What is Cancer?
In addition to describing cancer as being an uncontrolled growth of cells and explaining the potential causes of such growth, the mechanism of how signals enter a cell were described. These signals, which tell the cell what to do (eg grow), pass through a series of proteins and these proteins can mutate and cause uncontrolled cell growth, i.e. cancer.
The mutated proteins can give rise to one or more ‘hallmarks’ of cancer – the mechanism which causes cells to grow uncontrollably. Chemotherapy drugs are designed to act against a specific hallmark but none can act on all.
Hallmarks of Cancer (and what can be used against them)
The Immune System
The immune systems is our body’s way of dealing with cells which shouldn’t be in our bodies. Through various mechanisms, our own cells hunt down and destroy these cells. Normally they would act on cancer cells although they have their own mechanisms to defend themselves such as hiding, blocking the attack or even just turning off the body’s immune response.
Decades ago a man called William Coley discovered a way of using the body’s defence mechanisms by injecting people with bacteria after it was found that patients who had an infection after surgery to remove a tumour had a better prognosis.
Fast forward to today and non-harmful strains of BCG are being used to treat bladder cancer. Furthermore immune cells can now be removed from the body, engineered to recognise cancer cells an then used to kill them – click here for more information.
Cannabis and Cancer
Cannabis is predominantly made up of two ‘phytocannabinoids’ – CBD and THC as mentioned above. As also mentioned above, cells have signal pathways which control growth. Both THC and CBD have been proved in the laboratory to alter these signal pathways and affect the growth of cancer cells.
However, since different cancers can be caused by the mutation of different proteins, the effect that THC and CBD have will depend on the type of cancer they are being used on. In particular, cancers of the blood and brain appear to be specifically susceptible.
The team at St George’s, University of London (SGU) have been involved in investigating the effects of phytocannabinoids on cancer cells. Here are some of their research papers, some of which were alluded to as part of the presentation:
- Cannabis induced cytotoxicity in leukaemic cell lines: the role of the cannabinoid receptors and the MAPK pathway – looked into how THC influences cell signal pathways to bring about cell death
- The combination of cannabidiol and Δ9-tetrahydrocannabinol enhances the anticancer effects of radiation in an orthotopic murine glioma model – suggests CBD, alongside THC may be effective in enhancing the effects of radiotherapy
- Anticancer effects of phytocannabinoids used with chemotherapy in leukaemia cells can be improved by altering the sequence of their administration – as with the previous paper, CBD and THC have been shown here enhance another conventional cancer treatment, this time chemotherapy
So, both CBD and THC have been shown to kill cancer cells. This part of the presentation focussed in particularly on CBD. Much of it was in relation to the paper Enhancing the activity of cannabidiol and other cannabinoids in vitro through modifications to drug combinations and treatment schedules. The paper identified a particular protein which is affected by CBD and was found to be preventing cancer cells, in this case lukemia cells, from multiplying but was not found to be killing the cells… however…
The paper also found that the introduction of a break in the administration of CBD can kill cancer cells, i.e. “the cytotoxicity can be restored if the treatment regimen is altered to include a ‘recovery’ phase by culture in drug-free medium, as this allows the cell to re-engage cell cycling and thus undergo cell death”.
Professor Angus Dalgleish
As someone with a significant amount of experience in drug development, and co-author of many of the papers written about cannabis and cancer at SGU, Professor Dalgleish gave a very interesting presentation. In his opinion there is a strong case for moving the research on cannabinoids, in particular CBD, from lab-based to clinical trials although this can cost well in excess of £20,000,000. He also discussed the volume of anecdotal evidence he has collected which he hopes soon to publish – perhaps this approach will help speed along the commencement of these trials.
The following links were given at the end of the presentation:
I thought the presentation was extremely informative and am excited about the prospect of CBD moving closer towards clinical trials. With the amount of lab-based evidence, coupled with strong anecdotal evidence, there is such a strong case for moving the research on as quickly as possible.
Needless to say my opinion is that the effect of CBD on childhood brain tumours should be the primary focus of investigation – given that only three cancer drugs have ever been developed for childhood cancers, and given how little money goes into brain tumour research, surely kids like William deserve a break and for their cancers to be given the spotlight when it comes to such a promising new drug.