'Hitchhiking' viral therapy deals a double blow to cancer

June 13, 2012

Scientists have shown how a promising viral therapy that delivers a double blow to cancer can sneak up on tumours undetected by hitching a ride on blood cells.

The work, led by researchers from the University of Leeds and The Institute of Research (ICR), reveals how the 'hitch-hiking' is shielded from in the that might otherwise neutralise its anti-cancer properties.

The findings, from a study in patients, suggest that viral therapies like this can be effectively injected into the bloodstream during routine outpatient appointments - just like standard agents – making them potentially suitable for use against a wide range of cancers.

Reovirus is a promising new way of treating cancer that attacks the disease on two fronts. Not only does the virus kill directly, but it also triggers an immune response - like a vaccine – that helps eliminate residual cancer cells.

Many patient trials of reovirus are currently underway, including several in the UK led by the same University of Leeds and ICR scientists. Up until now, however, doctors have not been sure about the best way to deliver the experimental treatment. Although the virus can be injected directly into tumours, this is a relatively complicated procedure requiring considerable technical expertise. This delivery method also makes it difficult to treat tumours deep within the body, such as the liver, lungs, pancreas, and stomach.

Researchers had been concerned that reovirus might not reach the tumours it was supposed to treat if it was delivered intravenously, like standard are. They had expected that antibodies in the blood would mop up and neutralise the virus before it arrived at its intended target.

But now tests on a small group of patients have shown that this is not the case. In fact, not only did the virus stay active during its journey through the bloodstream but it also homed in on cancer cells, ignoring nearby healthy tissue.

University of Leeds' researcher Professor Alan Melcher, who receives funding from Cancer Research UK, jointly led the study. He said: "It seems that reovirus is even cleverer than we had thought. By piggybacking on , 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."

Dr Kevin Harrington from The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, who jointly led the study, 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 as outpatients.

Blood tests carried out shortly after treatment found the active virus associated with blood cells. Samples taken later showed that the hitch-hiking virus did not overstay its welcome with the cells and was cleared quickly from the system.

When researchers looked at pieces of tissue removed during surgery up to four weeks later, they found 'viral factories' and active virus in the , but not normal liver. This confirmed that the reovirus had been delivered specifically to the cancer after being injected into the .

Dr Julie Sharp, senior science information manager at 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 today in the journal Science Translational Medicine.

Explore further: Harmless human virus may be able to boost the effects of chemotherapy

More information: Adair, RA, "Cell Carriage, Delivery, and Selective Replication of an Onocolytic Virus in Tumor in Patients," Science Translational Medicine, 2012.

Related Stories

Harmless human virus may be able to boost the effects of chemotherapy

April 3, 2012
A naturally-occurring harmless human virus may be able to boost the effects of two standard chemotherapy drugs in some cancer patients, according to early stage trial data published in Clinical Cancer Research.

Researchers use human vaccine to cure prostate cancer in mice

June 19, 2011
University of Leeds researchers, funded by Cancer Research UK, have used a library of DNA to create a vaccine that could be used to treat cancer, according to a study published in Nature Medicine.

Recommended for you

Cell cycle-blocking drugs can shrink tumors by enlisting immune system in attack on cancer

August 16, 2017
In the brief time that drugs known as CDK4/6 inhibitors have been approved for the treatment of metastatic breast cancer, doctors have made a startling observation: in certain patients, the drugs—designed to halt cancer ...

Toxic formaldehyde is produced inside our own cells, scientists discover

August 16, 2017
New research has revealed that some of the toxin formaldehyde in our bodies does not come from our environment - it is a by-product of an essential reaction inside our own cells. This could provide new targets for developing ...

Researchers find 'switch' that turns on immune cells' tumor-killing ability

August 16, 2017
Molecular biologists led by Leonid Pobezinsky and his wife and research collaborator Elena Pobezinskaya at the University of Massachusetts Amherst have published results that for the first time show how a microRNA molecule ...

Popular immunotherapy target turns out to have a surprising buddy

August 16, 2017
The majority of current cancer immunotherapies focus on PD-L1. This well studied protein turns out to be controlled by a partner, CMTM6, a previously unexplored molecule that is now suddenly also a potential therapeutic target. ...

A metabolic treatment for pancreatic cancer?

August 15, 2017
Pancreatic cancer is now the third leading cause of cancer mortality. Its incidence is increasing in parallel with the population increase in obesity, and its five-year survival rate still hovers at just 8 to 9 percent. Research ...

Skewing the aim of targeted cancer therapies

August 15, 2017
Headlines, of late, have touted the successes of targeted gene-based cancer therapies, such as immunotherapies, but, unfortunately, also their failures.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.