Scientists have discovered when a cancer-killing virus is injected in the bloodstream it hitches a ride on blood cells and evades attack from the
immune system, allowing it to reach cancer tumors, and start destroying cancer cells. They suggest this means it may be possible to use promising "viral
therapy" during routine outpatient sessions, like chemotherapy, to treat a wide range of cancers.
Certain viruses, like the reovirus, that causes colds and mild stomach upsets, prefer to attack cancer cells. They also stimulate the immune system to attack
Using these "oncolytic" viruses to kill cancer is a fairly new approach that is currently being tested. Trials are currently under way to test "viral therapy" as an
approach to treat cancer in human patients.
But the challenge is how to get the viruses into tumors without alerting the immune system to destroy them. One way is to inject them into the tumors, but this
is technically difficult and particularly so for tumors that are deep inside the body, such as in the lungs, stomach, liver and pancreas.
Another way could be to inject the virus into the bloodstream; however, scientists have assumed this would not be feasible because the virus would likely be
spotted and destroyed by the immune system before it could reach the tumor.
But when a group of scientists decided to test this by injecting the virus into the bloodstream of patients with advanced colorectal cancer, they found the virus
was able to evade the immune system by "going under cover" and hitching a ride on red blood cells.
The study, led by researchers from the University of Leeds and The Institute of Cancer Research (ICR) in the UK, reveals how the "hitch-hiking" virus is shielded
from antibodies in the bloodstream that might otherwise neutralize its anti-cancer properties.
The team writes about its work in a paper published online in Science Translational Medicine on 13 June.
The study participants were 10 patients with advanced colorectal cancer that had spread to the liver and who were scheduled to undergo surgery on the
secondary tumors in their livers.
In the weeks leading up to their surgery, all patients received up to five doses of the reovirus as outpatients.
From blood samples taken shortly after treatment, the researchers found that the active virus associated with blood cells. Later samples showed the virus was
no longer in the blood cells and had quickly cleared from the system.
When the researchers examined samples of liver tissue removed during surgery up to four weeks later, they found "viral factories" and active virus in the tumor
samples but not in normal tissue samples. This confirmed the virus had travelled specifically to the tumor after being injected into the bloodstream.
Professor Alan Melcher of the University of Leeds, and Dr Kevin Harrington from The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust,
jointly led the study.
Melcher told the press:
"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."
Harrington commented that:
"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," he added.
He said if these treatments could only be delivered by injecting into the tumor, they would have limited use, but discovering that the virus "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," said Harrington.
Funds from Cancer Research UK, Leeds Experimental Cancer Medicine Centre, University of Leeds, The Institute of Cancer Research, Leeds Cancer Vaccine
Appeal, and the Rays of Hope Appeal, paid for the study.
Written by Catharine Paddock PhD
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today
"Cell Carriage, Delivery, and Selective Replication of an Oncolytic Virus in Tumor in Patients"; Robert A. Adair, Victoria Roulstone, Karen J.
Scott, Ruth Morgan, Gerard J. Nuovo, Martin Fuller, Deborah Beirne, Emma J. West, Victoria A. Jennings, Ailsa Rose, Joan Kyula, Sheila Fraser, Rajiv Dave, David
A. Anthoney, Alison Merrick, Robin Prestwich, Amer Aldouri, Oliver Donnelly, Hardev Pandha, Matt Coffey, Peter Selby, Richard Vile, Giles Toogood, Kevin
Harrington, and Alan A. Melcher; Sci Transl Med 13 June 2012 4:138ra77; DOI:10.1126/scitranslmed.3003578; Link to Abstract.
Additional source: Institute of Cancer Research.
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Visitor Opinions (latest shown first)
No Blanket Cure
posted by Barbara on 14 Jul 2012 at 12:19 pm
While I understand the frustration of cancer patients and survivors, there is no blanket cure. Notice in each article that these groups focus on a certain cancer (in this case, colorectal cancer). People spend millions to find a cure, but cancer encompasses hundreds of types and sub-types. For instance, breast and ovarian cancer has killed every woman in my family for the past six generations. No heart failure, stroke, accidents or fevers - just long, painful suffering with their children watching. So when I donate to cancer research, I donate to those two causes after researching the charity's credentials. I advise you to do the same.
There is always NEW idea's NEW trials after all these years of fund raisers and donations we still don't have a cure we have hope, hope doesn't give life back ! We hear of a virus can help then we hear it can cause more damage the good, then patient's can live up to 5 years ,so ! I want my child to live 90years not just 5 , I 'm tired of waiting and so are thousands of others ,work faster the he'll with nay Sayers we want our families and friends alive we need more than targeted therapies we need our lives!!!
The intro to this article with "Cancer-killing virus" is misleading as the article is really showing a delivery system with the virus in the blood stream reaching the tumor. No where does it really indicate that the virus itself was effective in killing/downsizing, etc the tumor. No doubt this headline will catch the public's attention, but more real information is needed. No wonder the public is so skeptical of medical news, and turns to even less reliable sources for their news.
I am not a doctor nor expert in any way, but I have been living with the scourge of this desease for a year. A loved one was diagnosed at 43 with stage IV colon cancer. Following surgery she has gone through 6 months of chemo therapy. I am fearful of a recurrence so I am quite hopeful about this new treatment. I would like to see more published about it.
While I think this could be effective, I think it can be too risky, for if the virus were to mutate, it can become deadly. Although viruses made with DNA instead of RNA are more stable, the possibility for mutation is always there, and because the nature of this virus, it can be very harmful if only one mutation occurred.
The biotechnology company that manufactured and provided the clinical reovirus (aka Reolysin) is Oncolytics Biotech, and they have many trial testing Reolysin in various cancer indications. A pivotal Phase 3 is underway in Head & Neck. Link to trial list: http://www.oncolyticsbiotech.com/clinical-trials
Missing information is the impact of virus on the tumors
posted by Tanya White on 15 Jun 2012 at 1:16 pm
Very interesting, informative and promising however I am surprised that there is really no discussion of the impact the virus had on the tumors. The natural following question would be, did the virus reduce the size and or/spread of the tumors. Simply finding something that will travel to the tumors does not indicate effective 'treatment'.
While is it simply amazing that this virus may avoid the immune system and rids the cancer cells, two questions arise. One, does this apply to second and third stage cancers as well? Second, avoiding the immune system, including the T-helper cells and B-cells, the body's main 'general' in the army of infection fighters, could this virus piggyback the red blood cells leading to the brain and the kidneys?
If they could, is there not a possibility that this virus may unleash its virulence on the irreplaceable neurones in the brain, leading to an array of brain-related diseases? If not, this could be major breakthrough.
'Virus Kills Cancer By Hitching Ride On Blood Cells'
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Cancer is a class of diseases characterized by out-of-control cell growth. There are over 100 different types of cancer, and each is classified by the type of cell that is initially affected.