The third day of the WFNOS conference started on rather a low note. There were three review presentations, each of which reported on recent clinical trials which had failed. In some cases, this followed a promising start in a small number of patients, but the results could not be reproduced in larger trials. The trial data is currently being reanalysed to determine whether subgroups of patients may have had a positive response, so there is still the potential that some of these drugs may eventually enter the market. In addition to clinical trial data, there are also a number of existing clinical databases which can be analysed in order to be able to identify who will react best to a specific therapy. Using detailed genetic, clinical and pathological data on thousands of patients obtained from a large national cancer database, a research group in France analysed 3,000 cases of type III glioma. Detailed mathematical analysis allowed the researchers to predict the prognosis in up to 82% of patients. Studies such as this will be vital in the identification of the best therapies for individual patients.
Of particular disappointment were the results from immunotherapy trials as these had appeared to hold great promise. Dr David Reardon from Boston went through each of them in detail to try to understand why this therapeutic approach had failed. The general conclusion is that brain tumours are unique so they are less likely to respond to the immune system in the same way as tumours in other parts of the body. So we need to try to understand the reasons behind these differences and use this information to design future trials. These may include the combination of a number of the drugs used previously, or the development of new drugs.
But, new drugs are extremely expensive to develop and wth such a high failure rate, not all drug companies are willing to invest in new drugs to treat brain tumours. Another approach is drug repurposing as some drugs which are already on the market may act on brain tumours. Our researchers at the University of Portsmouth have already demonstrated that aspirin can kill glioma cells. So work is now being carried out on “repurposing” this drug by designing a clinical trial which may start later this year. This is an exciting area of research and one in which the UK leads the field.
Overall, while the meeting was interesting, research into the treatment of brain tumours is still at a relatively early stage when compared with other cancers and I think that we particularly need to focus on the identification of viable targets for new drugs. Drugs which target known mutations, particularly in GBM, have shown little or no clinical benefit. This highlights the importance of the research being carried out at the Brain Tumour Research-funded Centres of Excellence. By combining basic molecular and cellular approaches, we are more likely to identify new and more viable drug targets.