Scientists have been given the go-ahead for one of the biggest ever gene therapy trials to investigate whether a modified form of the cold sore virus could save people with brain tumours.
The new treatment involves injecting a form of the herpes virus directly into the brain of patients with tumours.
The virus has been altered genetically so that it replicates inside the cancer cells and kills them off, but leaves the normal brain cells unharmed.
Three earlier and smaller trials yielded promising results, and some of the first patients who received the treatment years ago are still alive today despite being told at the time that they had only months to live.
Because it is such a new form of treatment, researchers at the University of Glasgow Hospitals Trust had to obtain permission from the government's gene therapy advisory committee.
The trial will recruit more than 100 patients from the UK and Germany, all of whom have a malignant glioma, an aggressive type of cancer for which there is currently no cure. They will be treated with a modified form of the herpes simplex virus.
In the normal brain the virus can cause encephalitis, an inflammation of the brain which is potentially fatal.
The modified virus has a gene removed, so that it starts replicating only when it comes into contact with cancer cells, bursting them and releasing more herpes virus in a chain reaction that quickly destroys the tumour.
So far 39 patients with glioma have taken part in three separate trials to test the safety of the treatment, which involved different approaches: injecting the virus directly into the tumour; injecting it into the tumour and then removing it; and removing the tumour and injecting the virus into the remaining cavity.
Five are still alive two years after receiving the pioneering therapy, and it is thought that one patient involved in the first trial in 1997 has survived. Others outlived their doctors' predictions while some died according to their prognosis.
The research team, led by Moira Brown, professor of neurovirology at Glasgow University, who works in the Beatson Oncology Centre, is keen to push ahead with the efficacy trial.
Brown founded Crusade Laboratories, a company linked to Glasgow University, which managed to attract venture capital money after the Medical Research Council withdrew its funding from the work a few years ago.
Brown has spent the past 25 years researching herpes and found out back in 1990 that the virus was able to destroy the cancerous cells while leaving the normal tissue unharmed.
She said: 'This is the most advanced gene therapy trial in the UK, and we are taking it onto a new stage, to study the efficacy of the treatment.'
Professor Norman Nevin, chair of the gene therapy committee, said: 'This treatment could offer hope to patients with malignant gliomas. After carefully considering the risks and benefits, the committee has decided to give the go-ahead to further trials so that we can demonstrate the effectiveness of this therapy.'
