Brain tumours kill more children and adults under the age of 40 than any other cancer
The annual NCRI conference
The annual NCRI conference brings together some of the key UK and international cancer researchers to discuss the key research advances. Rather than focusing specifically on individual cancer types, the conference addresses topics which could be applied across a range of different cancer types, including brain tumours.
One of the key themes this year was the development of immunotherapy. This is a form of treatment which stimulates the body’s own immune response to recognise tumour cells as being foreign and then destroying them. Although the results to date in trials for brain tumour have been disappointing, in fact only 20% of people with all types of cancer currently benefit from immunotherapy. So, a significant amount of research is being carried out to try to understand why this therapy has such a low success rate, and how we can better predict who is most likely to react to the drugs.
In order to benefit from immunotherapy, the body needs to have a strong local immune response, particularly around the area of the tumour, which can then be activated by the therapy. However, this is not the case for all people or all tumours, and the presence of such a response is one of the key determinants to predict a positive response to an immunotherapeutic drug. Research is now being carried out to determine which markers within a tumour, usually identified from a biopsy sample, are most likely to predict a positive response and if we can use this information to develop new and more effective immunotherapy drugs. Another question raised was whether such therapies should be given prior to surgery, as the excision of the main part of the tumour may also take away some of the immune cells which would normally be activated by immune therapies. While the majority of this research is being carried out in non-brain tumours, and we know that the immune response in the brain is different to other parts of the body, the information that is obtained from the studies of other cancer types can help to inform us about how these types of therapies could possibly be translated into better treatments for brain tumours.
The conference provides an opportunity for clinicians to announce the results of key clinical trials. A study co-ordinated by Prof Anthony Chalmers from Glasgow assessed the potential benefit of the drug olaparib for the treatment of glioblastoma (GBM). This drug is currently used for the treatment of ovarian cancer and does usually enter into the brain. However, initial research suggested that the blood brain barrier – a membrane which protects the brain – may be disrupted close to a tumour and this may permit certain drugs to gain access to the tumour. This initial study assessed whether the drug, when given in combination with temozolomide, could slow down the progression of a recurrent GBM. The results were promising, although there were some significant toxic side effects reported. A larger study is now being planned to determine if the initial benefits are maintained over time, and whether the drug would also benefit patients who are being treated with radiotherapy.
Cancer prevention was another key theme at this year’s meeting. We know that smoking is responsible for the development of lung cancer and there is increasing evidence that obesity is also a risk factor, particularly for breast and colorectal cancer. Additional studies have also reported on the role of individual dietary components on cancer development. While a lot of research has been carried out on the role of lifestyle in the development of the more common cancers, there is very little evidence available to date on its role in the development of brain tumours. This is more complex considering the number of types of brain tumours and the wide age range when they can occur. Whilst we await further studies in this area, the recommendations are to follow a healthy diet and lifestyle as this is likely to impact on the development of all types of cancer as well as the potential to respond to treatment.
Proton beam therapy has been hailed by some as being the next big breakthrough in cancer treatment. It potentially has the benefits of radiotherapy while having minimal damage to the tissue surrounding the tumour. This could be of particular benefit to certain types of brain tumour. A keynote lecture by Prof Anthony Zietman from Massachusetts General Hospital, who is one of the pioneers in the field, provided an update on this therapy and what we can learn from the experience of its introduction in the US from the mid 1990s. When the therapy was first developed, it was hailed in the popular press as a potential cure for cancer. But this was based on the theory of how the therapy works, rather than actual experimental evidence. Unfortunately, both the media and key lobby groups within the US have significant influence on the availability of therapies – it is one of the few countries where advertisements for prescription drugs are permitted – and proton beam therapy has been used routinely in the clinic for over 20 years without sufficient robust evidence that it actually works. Over 70% of the cases treated were for prostate cancer and retrospective analysis has now shown that most of these patients would have survived as well, if not better, if they had been treated with more conventional treatment, or even if they had only undergone observation. Prof Zietman suggested that we have an opportunity here in the UK to learn from this with the two proton beam facilities being introduced next year in London and Manchester. Before being used routinely in the clinic, appropriate research should be carried out to demonstrate that the therapy is both safe and effective, but also that it is better than the existing therapies. The limited availability of the therapy means that it should only be used for cases where it is going to be of definite benefit. And, indeed, this applies to all new cancer therapies.
So, looking back, I have a number of take-home messages. Although there was very little specific brain tumour research reported at the NCRI meeting, there is a lot of exciting research being carried out which can help to inform us about the biology of brain tumours and how we can make use of this information to help to develop new therapies. Immunotherapy holds great promise, but we need to understand the biology of brain tumours much better in order to develop this approach. Our research centres are working hard to really understand the changes that occur in brain tumours. And we need robust research evidence before we before we can support new therapies. One area of particular promise is the use of existing drugs for the treatment of brain tumours, and we are working hard to ensure that the appropriate trials are carried out as fast as possible.