Faulty enzyme may contribute to malignant brain tumour formation

US scientists have discovered that a faulty enzyme may contribute to the formation of some malignant brain tumours.

Around 70 per cent of people with a type of brain tumour - called a low-grade glioma - have a faulty version of an enzyme called IDH1. The mutation is also found in a significant proportion of patients with acute myeloid leukaemia.

Research led by Agios Pharmaceuticals has now shown that mutations in this enzyme result in unusually high levels of a metabolite called 2-hydroxyglutarate (2HG) in the brain, which has previously been linked to the development of brain cancer.

This study is the first evidence of a role for IDH1 in the development of cancer.

Although the enzyme was known to be faulty in gliomas, scientists did not understand exactly how it could contribute to the disease.

The team, whose findings are published in the journal Nature, analysed samples of tissue taken from malignant gliomas and found that those with faults in the IDH1 enzyme typically had 100 times more 2HG than those with the normal IDH1 enzyme.

It may now be possible to develop a diagnostic test that identifies patients with gliomas that harbour the IDH1 mutation by measuring the levels of 2HG in their brain. Evidence suggests that patients with the mutation tend to do better than those without.

The research could also lead to treatments that block the production of 2HG, which in turn could delay the progression of this kind of brain tumour.

Professor Lew Cantley, director of the Cancer Centre at the Beth Israel Deaconess Medical Centre and founder of Agios Pharmaceuticals, described the work as "groundbreaking".

"The team at Agios has demonstrated that what was previously considered an inactive enzyme is in reality an active oncogene and a potential therapeutic target," he confirmed.

"This has fundamentally changed our understanding of the field. Additionally, there is an easily measured metabolic biomarker, 2HG, that will help in the diagnosis and treatment of any related therapeutics that arise from this work."

Dr Laura Bell, science information officer at Cancer Research UK, said: "This study has brought exciting new information to light which could eventually help doctors understand more about how certain brain tumours are likely to progress - and how best to treat them.

"But there is still some way to go before this new information could be used to help treat people with cancer."