Leeds scientists: common virus could treat brain tumours

A virus injected directly into the bloodstream could be used to treat people with aggressive brain tumours, a major new study reports.

Scientists have found that the naturally occurring virus could act as an effective immunotherapy in patients with brain cancer or other cancers that have spread to the brain.

They showed that a type of virus called reovirus could cross the blood-brain barrier to reach tumours, where it replicates and kills the cancer cells.

They also found that the virus was able to ‘switch-on’ the body’s own defence systems to attack the cancer.

The study authors, from the University of Leeds and The Institute of Cancer Research in London, believe reovirus therapy could be used in conjunction with other cancer therapies to make them more potent – and a clinical trial is currently underway.

Experts say because the virus infects cancer cells and leaves healthy cells alone, patients receiving the treatment reported only mild flu-like side effects.

Up to now, scientists thought it was unlikely that the virus would be able to pass from the blood into the brain because of the blood-brain barrier, a protective membrane around the brain.

But the research demonstrated that the virus could be administered through a single-dose drip.

Human trials underway

Nine patients took part in the study which led to the publication of the new research. They had cancers that had either spread to the brain from other parts of the body or were fast-growing gliomas, a type of brain cancer that is difficult to treat, and has a poor prognosis.

All patients were due to have the tumours removed surgically. But in the days before the surgeons operated, the patients were given the virus drip.

Once the tumours were removed, samples were taken and analysed for signs that the virus had been able to reach the cancer, sometimes deep within the brain. In all nine patients, there was evidence that the virus had reached its target.

The researchers also found that the presence of reovirus stimulated the body’s own immune system, with white blood cells or ‘killer’ T-cells being attracted to the tumour site to attack the cancer.

Dr Adel Samson, co-lead author and medical oncologist at the Leeds Institute of Cancer and Pathology, at the University of Leeds, said: “This is the first time it has been shown that a therapeutic virus is able to pass through the brain-blood barrier, and that opens up the possibility this type of immunotherapy could be used to treat more people with aggressive brain cancers.

“This study was about showing that a virus could be delivered to a tumour in the brain. Not only was it able to reach its target, but there were signs it stimulated the body’s own immune defences to attack the cancer.”

In a world first, a new trial has started where patients will be given reovirus in combination with the standard treatment of radiotherapy and chemotherapy which follows surgery.

One patient with a form of brain cancer called glioblastoma is already receiving the combined therapy. In the months following removal of the tumour, he will receive a total of 16 doses of virus alongside chemotherapy and radiotherapy.

The trial is being led by Susan Short, Professor of Clinical Oncology at the University of Leeds. She said: “The presence of cancer in the brain dampens the body’s own immune system. The presence of the reovirus counteracts this and stimulates the defence system into action.

“Our hope is that the additional effect of the virus on enhancing the body’s immune response to the tumour will increase the amount of tumour cells that are killed by the standard treatment, radiotherapy and chemotherapy.”

She added: “Brain cancer is a devastating disease. For a long time, there have not been many new developments that we could offer patients but the research that is happening at the University Leeds and elsewhere is beginning to offer a new approach.”

The Leeds-led trial will identify if the combined therapy can be tolerated by patients and whether it is toxic. But Prof Short says the longer term aim, in wider partnership with other UK research centres, is to see if the virus makes the standard treatment more effective.

Prevalence of brain cancer

According to figures from Cancer Research UK, almost 11,000 new cases of primary brain cancers are diagnosed in the UK each year. Only 14 percent of patients survive for 10 years or more years following a diagnosis of a primary or malignant brain tumour.