Cancer targeted by 2 viruses in made-in-Canada therapy
Genetic mutations that make cancer cells grow quickly also make them susceptible to viruses
A made-in-Canada combination of two viruses to target and attack tumours started its first clinical trial experiments in humans.
At a news conference Friday at the Ottawa Hospital, researchers announced a Phase 1 clinical trial to test the safety of attacking cancer using a variation of the common cold virus called adenovirus and another virus called Maraba that was first found in Brazilian sand fleas.
The idea of using viruses to fight cancer started more than 100 years ago when scientists first noticed some patients improved after they got sick from an infection.
When cells become cancerous, it's like they're making a deal with a devil, said John Bell, a senior scientist at Ottawa Hospital. The genetic mutations that allow them to grow quickly also make them susceptible to viruses.
But to exploit that vulnerability more effectively, researchers now use genetic engineering to disable their disease-causing properties, better target cancer cells and take aim at them while leaving healthy cells alone.
"It's only in the last 10 years that we understood enough about cancer biology and virus biology and genetics in order to engineer viruses that can work," Bell said.
First, researchers had to identify a target protein, called MAGE-A3, that is expressed in the cancer cells and not normal cells. They estimate about 40 per cent of cancers do.
It's hoped that the adenovirus will work to prime the patient's immune system and then the Maraba virus will kill the cancer cells.
Christina Monker was one of the first nine people to receive the combination of viruses. The 75-year-old former nurse from Rockland, Ont., had anal cancer that spread to her lungs. She went through 30 rounds of chemotherapy before enrolling.
"That's almost my last chance because the chemotherapy didn't work anymore," Monker said.
The first couple of days after the first infusion she said she felt like she had the flu.
"It's too soon to say if this therapy has affected my cancer," said Monker. She hopes future generations will benefit from the knowledge gained through the trial on the up to 79 patients in Ottawa, Toronto, Hamilton and Vancouver.
The ultimate effectiveness of the nine anti-cancer viruses that doctors and scientists want to "blow up" tumours are in various stages of clinical trials worldwide, said Robertu Cattaneo, a professor of biochemistry and molecular biology at the Mayo Clinic in Rochester, Minn. He studies the use of measles viruses to fight lymphoma.
"These viruses will be very useful for individual patients, maybe for some groups of patients," Cattaneo said. "These will not be a panacea, these will not substitute chemotherapy or radiation therapy."
Bell said he doesn't want to raise people's hopes unnecessarily. "We're trying to say there are advances being made and this is something that they funded and supported that's gotten all the way to human testing."
With files from CBC's Kelly Crowe