WEST YORKSHIRE, England — Scientists may have made a major breakthrough in treating — and potentially defeating — cancerous brain tumors by injecting patients with a virus that actually stimulates the immune system.
Researchers at the University of Leeds conducted a study on nine patients battling fast-growing gliomas, which are aggressive tumors that are tough to treat and typically come with a grim outlook. The participants were scheduled to have the tumors removed surgically, but in the days prior to the procedure, they were injected with the naturally occurring “reovirus” through an IV drip.
Reovirus has been shown to attack cancer cells without impacting healthier cells in the body.
Once in the bloodstream, the virus would have to pass through the protective membrane surrounding the brain known as the blood-brain barrier in order to take a toll on the tumors. If this could happen, they predicted the virus could replicate once inside the tumors and kill cancerous cells.
“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,” says Susan Short, Professor of Clinical Oncology at the school.
Still, the authors had cautious optimism in the virus passing through the barrier. They feared the attempt would fail and a more likely scenario would force them to have to inject the virus directly into the brain — a more delicate and dangerous procedure not suitable for all patients.
Incredibly, that predicament wouldn’t be necessary. After the tumors were removed from the patients, tests showed that the virus did in fact penetrate the barrier and reached the cancer in each patient. Moreover, the researchers discovered the virus stirred up the patients’ immune systems to battle back against the tumors, causing white blood cells to attack the cancerous ones.
“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,” says Dr Adel Samson, a medical oncologist and co-lead author of the study, in a university release.
Adds co-lead author Alan Melcher, a professor of translational immunotherapy at the Institute of Cancer Research in London: “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.”
Melcher says that once the tumors were infected with the reovirus, the cancer cells were then “visible” to the immune system. The team is now testing their results in a clinical trial where patients at the St. James Hospital in Leeds are being treated with the reovirus IV-drips in concert with other standard cancer treatments.
“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,” explains Short.