One day, malignant tumours may be cured by the relatively simple injection of a particular virus, according to recent medical research at the University of Calgary.
Although U of C researcher Dr. Peter Forsyth can't promise anything yet, he and his colleagues at Calgary's Tom Baker Cancer Centre have made significant new advances toward the testing of a cure for a specific type of brain tumour called glioma. This type of cancer spans both hemispheres of the brain and establishes a network of potentially malignant cells in the periphery of the central tumour.
Dr. Forsyth draws his inspiration from having dealt with many patients who died of brain cancer.
"It's probably one of the most serious and fatal cancers known to mankind," he said. "The average survival of patients is only a year. One of the most disappointing features is that the prognosis hasn't changed in 20 years, so it's obvious that we have to do a better job of this."
The research team's findings stem from a discovery at the U of C by Dr. Forsyth and his colleague Dr. Patrick Lee. Cancer cells multiply rapidly because one of their biochemical pathways is extremely active. It was discovered that a common human virus, the Respiratory Enteric Orphan virus, selectively kills cells with the activated pathways. This selective destruction is not limited to, but includes cancer cells. Moreover, because of the involvement of the active pathway, a highly malignant tumour will be more affected by the treatment than a less prolific growth.
This discovery sent shockwaves through the international research community and set the stage for a June 19 press conference, where Dr. Forsyth unveiled practical test results of his findings.
Dr. Forsyth's initial work showed that REO virus killed most glioma cell lines. The next step was to introduce live virus into a cancer-infected host. The results were astounding: after a single injection of virus, tumours in mice disappeared within several days. Furthermore, the effects were not only observed at the site of injection into one tumour, but at other cancerous masses far from the injection site, according to Dr. Forsyth.
"This is very probably the most important [aspect of the discovery]," said Dr. Forsyth. "This raises the possibility of killing cancer cells removed from the tumour site. For example, if someone has breast cancer, the problem is not so much the lump in the breast, which can be surgically removed, but the tumour cells that get into the bloodstream and head to the brain, or to somewhere else."
In the test cases, a single two microlitre dose of live REO virus was injected into the brains of mice with established 19-day-old cancerous cells. After several days, the tumour had nearly disappeared, leaving a small number of microscopic areas of reactive cells. The spots may represent cases of encephalitis caused by the viral infection, but Dr. Forsyth explained that despite extensive analytical testing, the nature of the reactive cells remains a mystery. The residue could be one of millions of possible particles. However, the relative size of the small number of molecules compared to the field in which they lie makes them very difficult to isolate.
"The discovery is huge, if it works. This is another step in the process of determining if the new treatment is going to be effective," said an excited Dr. Forsyth. "At this point, we can't tell if it's going to work in patients, but it's the most exciting thing we've ever seen."
Currently, several Health Science research teams are investigating the effects of the virus on various other types of the disease, including cancers of the prostate, skin and breast. Dr. Forsyth expects a clinical trial of glioma treatment with REO virus to begin within six months. If all goes well, he estimates that a REO virus-based cancer therapy could be publicly available between three and five years from now.