Yorkshire virus breakthrough holds out hope of cancer cure

Latest findings from a new trial in patients indicate not only does the virus kill cancer cells directly, but it also triggers an immune response – like a vaccine – that helps kill remaining cancer cells.

Experts at Leeds University and the Institute of Cancer Research in London say the virus is shielded from antibodies in the bloodstream that might otherwise neutralise its anti-cancer properties.

The discovery – which is attracting international attention – suggests viral therapies could be effectively injected into the bloodstream, making them potentially suitable against a wide range of cancers.

The world-leading research is part of work which could herald a revolution in cancer treatment leading to a new generation of therapies using viruses and the body’s own immune system, alongside traditional chemotherapy and radiotherapy, to target the disease.

Tests in patients using the common reovirus, which is typically harmless in humans, are under way in a number of trials worldwide including the UK after laboratory research revealed it had a remarkable impact on cancer.

But until now doctors have not been sure over the best way to ensure the experimental treatment reaches the right cells.

Although the virus can be injected directly into tumours, this is complicated as it requires a high level of expertise and also makes it difficult to treat tumours deep within the body, such as the liver, lungs, pancreas and stomach.

Researchers had also been worried that it might not reach tumours if it was delivered through the bloodstream like standard chemotherapy drugs because the body’s own defences would attack and neutralise the virus before it arrived at its intended target.

Now tests on a small group of patients at St James’s Hospital in Leeds have revealed that not only did the virus stay active during its journey through the bloodstream but it also homed in on cancer cells, ignoring healthy tissue.

Prof Alan Melcher, of Leeds University, who jointly led the study, said that if trials using the virus proved successful, the therapy could become routinely available within a few years.

He said: “It seems that reovirus is even cleverer than we had thought.

“By piggybacking on blood cells, the virus is managing to hide from the body’s natural immune response and reach its target intact. This could be hugely significant for the uptake of viral therapies like this in clinical practice.”

Study co-leader Kevin Harrington, of the Institute of Cancer Research and the Royal Marsden NHS Foundation Trust, said: “Viral treatments like reovirus are showing real promise in patient trials. This study gives us the very good news that it should be possible to deliver these treatments with a simple injection into the bloodstream.

“It would have been a significant barrier to their widespread use if they could only have been injected into the tumour, but the finding that they can hitch a ride on blood cells will potentially make them relevant to a broad range of cancers.

“We also confirmed that reovirus was specifically targeting cancer cells and leaving normal cells alone, which we hope should mean fewer side-effects for patients.”

The study involved 10 patients with advanced bowel cancer who were due to have surgery on tumours that had spread to the liver. All patients were given up to five doses of the reovirus in the weeks before surgery.

When researchers looked at pieces of tissue removed during surgery, they found ‘viral factories’ and active virus in the tumour, but not in normal liver. This confirmed the reovirus had been delivered to the cancer.

Julie Sharp, senior science information manager at Cancer Research UK, which part-funded the research, said: “This promising study shows that reovirus can trick the body’s defences to reach and kill cancer cells and suggests that it could be given to patients using a simple injection. We look forward to seeing how this research develops and if this could one day become part of standard cancer treatment.”

Full details of the work are published in the American journal Science Translational Medicine.

The work was further funded by Leeds Experimental Cancer Medicine Centre, Leeds University, the Institute of Cancer Research, Leeds Cancer Vaccine Appeal and the Leeds-based Rays of Hope Appeal.