The virus, called reovirus, could act as an effective immunotherapy in patients with brain cancer.
Scientists at the University of Leeds, the Institute of Cancer Research (ICR) in London and other facilities in Britain, the US and Canada have shown the virus, which would be directly injected into the bloodstream, could cross the blood-brain barrier to reach tumours, where it would then replicate and kill the cancer cells.
During the study which has been published in the journal Science Translational Medicine, the virus was found to be able to ‘switch-on’ the body’s own defence systems to attack the brain tumours in humans.
Nine patients, who 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 – took part in the study.
While all the patients were due to have the tumours removed surgically, in the days before their operations they were given a dose of the virus.
When the tumours were removed, samples were taken to see if the virus had reached the cancer.
In all nine patients there was evidence the virus had reached its target.
Co-author Professor Alan Melcher, Professor of Translational Immunotherapy at the ICR, said: “Our immune systems aren’t very good at ‘seeing’ cancers – partly because cancer cells look like our body’s own cells, and partly because cancers are good at telling immune cells to turn a blind eye. But the immune system is very good at seeing viruses.
“In our study, we were able to show that reovirus could infect cancer cells in the brain. And, importantly brain tumours infected with reovirus became much more visible to the immune system.
“This small-scale clinical trial allowed us to ask a crucial biological question about cancer immunotherapy and gain insights which can now be tested further, both in the laboratory and in the clinic.
“Now we know we can get reovirus across the blood-brain barrier, we have begun clinical studies to see just how effective this viral immunotherapy can be at extending and improving the lives of patients with brain tumours, who currently have very limited treatment options available to them.”
Hospitals in Leeds, Manchester and Glasgow have now begun a 24-patient clinical trial testing whether it is safe to use the reovirus alongside chemotherapy and radiotherapy against brain cancers, reported The Times.
Leading the trial is Prof Susan Short, Professor of Clinical Oncology at the University of Leeds.
“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.
“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.”