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Canada Tests Combo Viral Therapy for Cancer Patients

Maraba virus and adenovirus deliver one-two punch

Canadian researchers have launched the world’s first clinical trial of an investigational therapy that uses a combination of two viruses to kill cancer cells and to stimulate an anti-cancer immune response. Previous research has suggested that this approach could have fewer adverse effects than conventional chemotherapy and radiation, although it will take years to complete the current trial, according to the investigators.

The therapy was jointly discovered and is being developed by researchers at the University of Ottawa and McMaster University. The new study is expected to enroll up to 79 patients at four hospitals in Canada. Up to 24 patients will receive one of the viruses, and the rest will receive both, 2 weeks apart.

The idea of using viruses to treat cancer has been around for more than a century, with sporadic reports of cancer patients experiencing remarkable recoveries after viral infections. However, it is only in recent years that viral therapy has begun to be developed and tested in a rigorous way.

The two viruses being studied in the new trial are called MG1MA3 and AdMA3. MG1MA3 is derived from the Maraba virus, which was first isolated from Brazilian sandflies, whereas AdMA3 is derived from the adenovirus, which is responsible for the common cold. Both of these viruses have been engineered to stimulate an immune response against cancer cells that express a protein called MAGE-A3, but the Maraba virus also provides additional anti-cancer activity by replicating inside many kinds of cancer cells and killing them directly. The viruses are manufactured in specialized facilities at the University of Ottawa and at McMaster University.

“The idea behind this trial is to use the adenovirus to prime the patient’s immune system to recognize their cancer, and then use the Maraba virus to directly kill their cancer and further stimulate their immune system to prevent the cancer coming back,” said Dr. Brian Lichty, associate professor at McMaster University. “We’re enthusiastic about the potential of this unique therapy.”

Viral treatments are one component of immunotherapy (also called biotherapy), which seeks to use biological materials –– such as cells, genes, antibodies, and viruses –– to attack cancer cells and to stimulate an anti-cancer immune response.

Source: Ottawa Hospital Research Institute; July 10, 2015.


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