Monday 12 July 1999
A new gene therapy is being developed by The Royal Marsden Hospital and The Institute of Cancer Research which could offer the first real improvement in the treatment of brain tumours for decades.
Scientists have developed a range of anticancer pro-drugs which can be activated within tumour cells by a gene delivery system for patients with brain tumours, some forms of which have very low cure rates with current treatments.
The work is being led by Dr Gill Ross and Dr Caroline Springer, bringing together expertise in brain tumour biology and gene therapy respectively.
Dr Ross, Senior Lecturer at The Institute of Cancer Research and Honorary Consultant at the Royal Marsden said, "There is currently no prospect of screening patients for brain tumours or of identifying pre-disposing risk factors which might help us in the early detection of the disease, so more effective therapy is our best hope of reducing mortality."
At present, conventional drugs have a severely limited effect on brain tissue. The research team working on this project are aiming to overcome some of these drug access problems by injecting bacterial genes directly into the tumour.
These genes, which cannot spread beyond the dividing cells of the tumour, trigger the production of an enzyme which is capable of switching on inactive chemotherapy drugs - so called pro-drugs - to become active agents which can kill tumour cells.
Scientists at the ICR, headed by Dr Springer, have been very successful in the development of pro-drugs which can be activated by this method and research is underway to assess their application against some other types of cancer, as well as brain tumours.
Approval for clinical trials on 'Gene Directed Enzyme Pro-Drug Therapy for Brain Tumours' is due to be sought, following the completion of pre-clinical laboratory trials.
It is anticipated that pro-drug gene therapy will be used in conjunction with radiotherapy, which is currently the standard treatment for brain tumours after surgical intervention. The problem currently is that radiotherapy alone has limitations because of the resistance of brain tumours to radiation. Radiotherapy combined with pro-drug therapy has the potential to overcome problems of resistance to such treatment.
The research project, funded by an £80,000 grant from the Samantha Dickson Trust, is important because of the devastating effect of brain tumours on adults and children, among whom it is the second commonest tumour type after leukaemia in the under 18s.
Dr Ross added: "Preliminary laboratory data in other tumour types suggests that this pro-drug gene therapy approach is not only feasible, but also effective, certainly under laboratory conditions. It is therefore important to evaluate it in brain tumour preliminary studies, given limitations in conventional chemotherapy and radiotherapy."
It is estimated that in 1998 more than 40,000 new cases of brain tumours (otherwise known as tumours of the central nervous system) were diagnosed in the European Union, with some 30,000 deaths.
Notes to editors:
- There are currently three approaches to gene therapy. One approach attempts to introduce into every tumour cell a correct functioning copy of a gene that is known to be defective in that tumour. However, this is severely limited by the inefficiency of our ability to introduce genes into large numbers of cells and the practical fact that most cancers have defects in numerous genes.
- A second approach introduces genes in the vicinity of the tumour which stimulate the host's immune reaction. This has proven to be limited in effectiveness to a small number of cancers which the body already partly recognises as being "foreign".
- The form of gene therapy being investigated by the Institute of Cancer Research and The Royal Marsden Hospital as a potential direction for brain tumour therapy is quite different. The bacterial genes, wrapped in a virus, are injected directly into the tumour. They switch on production of an enzyme in the tumour cells which then switches on otherwise inactive chemotherapy drugs, called the pro-drugs, to become active agents capable of killing tumour cells.
For further information please contact The Press Office on:-
Tel: 0207 970 6030
email: [email protected]
Please note:
Unfortunately the press office are unable to answer queries from the general public. For general cancer information please refer to The Institute's cancer information page.