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Virus trained to seek and destroy cancer

cancer_targeting

Researchers have found a way to modify viruses that use markers to find and destroy cancer cells. “Our research points to a new method to construct viruses for gene therapy and has so far been promising in the lab. We now need to test these gene therapies in patients to see if they are as effective treating cancer as our research suggests,” says lead researcher John Chester. (Credit: iStockPhoto with some modifications)

U. LEEDS (UK)—Researchers have found a way to modify viruses so they are able to hunt down and wipe out cancer cells.

Scientists at the University of Leeds used unique markers that appear on the surface of cancer cells to engineer proteins that recognize and attach to these markers, that can be added to a virus so that it recognizes and infiltrates cancer cells. Details of the study are published in the journal Gene Therapy.

The virus can then deliver genes that can make cancer cells more sensitive to drugs, introduce “suicide” genes to the cancer cell, or replace the missing and defective genes that caused the cancer to develop—an approach called gene therapy.

Gene therapy has had limited success, mainly because the approach to deliver such treatments have not been efficient or specific enough to only target tumor cells.

“Gene therapies have been out of fashion over the last couple of years. This isn’t an indication that they don’t work; just that we haven’t found the best way to use them yet,” says John Chester, a scientist at Leeds who led the Cancer Research UK funded study.

“Our research points to a new method to construct viruses for gene therapy and has so far been promising in the lab. We now need to test these gene therapies in patients to see if they are as effective treating cancer as our research suggests.”

The scientists developed their system by engineering “retargeting” proteins to recognize markers on the surface of bladder cancer cells, and potentially to any kind of cancer.

When tested in the lab the virus was able to recognize and enter the cancer cells with the markers. They were also able to add retargeting proteins to an existing gene therapy virus so that it recognized and attacked bladder cancer cells, increasing their drug sensitivity.

Researchers propose a number of possible uses for the system. In the first approach, a targeting protein that recognizes a range of tumors could be combined with an existing gene therapy virus.

Another approach involves tailoring the targeting proteins to an individual patient. By examining the markers on a patient’s tumor it would be possible to add a re-targeting protein designed specifically for their cancer to a gene therapy virus.

“We also found that we weren’t limited to using only one targeting protein for each virus, Chester says. “We were also able to combine the virus with two different targeting proteins so that our virus can target a range of different tumor markers.

“This approach could be a step forward for gene therapy, particularly as it is quicker, easier and cheaper to mix and match the targeting proteins rather than engineer a completely new gene therapy virus.”

Lesley Walker, director of cancer information at Cancer Research UK, says: “This exciting early laboratory work points to a new way of attacking cancer cells by targeting the unique markers on cancer cells.

“It could have real benefits for patients with treatments tailored to their cancer but we first have to test it through clinical trials.”

More University of Leeds news: www.leeds.ac.uk/news

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