The first study to bring out the potential of using a virus to fight human malignancies has shown that a modified small pox vaccine can help shrink tumors in some cancer patients, and spare the healthy cells at the same time.
The virus, known as JX-594, is the same strain that is used in the smallpox vaccine called vaccinia virus. Twenty three patients in advanced stages of cancer were injected with varying amounts of the virus. Out of the 23, six participants who received the highest dosage had their tumours stabilise and shrink.
John Bell, one of the study?s authors and a cancer research scientist at Ottawa Hospital Research?Institute said that the results came from the first of three testing stages generally required for regulatory approval. ?It?s never been shown before that we could do this in humans,? Bell said in an interview. ?We even see in some patients a modest therapeutic benefit.?
The report was released in the journal, Nature, and claimed that in the trial the virus that was injected into the blood stream, infected and spread within tumours without harming other cells.
The new approach was developed by San Francisco-based?Jennerex Inc. The company?s name is based on Edward Jenner, an 18th century English scientist who developed the first vaccination with an inoculation against the related cow-pox virus.
It will be tested in a broader trial and if successful, the method could provide hope for patients whose cancer has spread beyond one area. Professor Bell acknowledged the very early stage at which the research stands, but added: “Some day, viruses and other biological therapies could truly transform our approach for treating cancer.”
The vaccinia virus is similar to smallpox but it doesn?t contain smallpox, and thus, it cannot cause the disease. Researchers used it for seeing because of its natural ability to replicate itself in cancer cells, the report explained. It was then modified to enhance its cancer-fighting properties.
Several cancer vaccines have been released, such as Merck?s Gardasil shot that targets the virus causing cervical cancer. Dendreon Corporation has released Provenge, which stimulates an immune response against prostate cancer cells. However, health analysts believe the latest development is quite unconventional.
?The big problem with cancer is not people showing up with one tumour you can excise with a scalpel. The problem is metastatic disease that you can?t even see where it is,? Bell said. ?By putting the virus in the blood system, it allows the virus to go around and potentially find all the fertile ground for it to grow in, all the places tumours are, and once it does that, it can affect them all and destroy them.?
Side effects such as mild to moderate flu-like symptoms that lasted less than a day in some patients of the trial were observed.
The study was financed by Jennerex, Terry Fox Foundation, Canadian Institute of Health Research, Ontario Institute for Cancer Research and several others. Jennerex has sufficient funds to carry out another set of experiments but it is likely to look for additional funding.
Professor Nick Lemoine, director of Barts Cancer Institute, said: “Viruses that multiply in just tumour cells – avoiding healthy cells – are showing real promise as a new biological approach to target hard-to-treat cancers? While praising the new study, he added: “This new study is important because it shows that a virus previously used safely to vaccinate against smallpox in millions of people can now be modified to reach cancers through the bloodstream – even after cancer has spread widely through the patient’s body.
“It is particularly encouraging that responses were seen even in tumours like mesothelioma, a cancer which can be particularly hard to treat.”
The word, ?virus?, generally evokes a sense of displeasure for those who hear it as viruses are labeled in a way to describe living substances that cause harm to one?s body. But this is not the first time a virus has been proven to bring about some sort of immunity to the body which it infects. The new findings could be the light at the end of the tunnel for many cancer patients.
Sources: Bloomberg, BBC