In a perfect world, there would be no cancer. And if there were, patients would be able to stimulate their own immune system to destroy tumours with a virus designed to kill only cancerous cells and leave healthy ones unharmed.
Discovering viruses with this incredible potential – and then using them to better treat cancer patients - are the goals of the Canadian Oncolytic Virus Consortium (COVCo), a research project led by Dr. John Bell. The team was recently awarded $7.4 million from Terry Fox Research Institute to accelerate their work over the next five years.
One of the biggest problems in cancer treatment is that current therapies attack not only the cancer but also normal tissues, resulting in unwanted toxicities that harm patients, says Dr. Bell. To counter this, his team is developing biotherapeutics, or therapeutics that use biology to attack cancer cells instead of using chemicals or radiation.
“One particular focus of our group is to make new oncolytic viruses that can specifically infect and kill tumour cells, but that don’t infect normal tissues,” says Dr. Bell, based at Ottawa Hospital Research Institute. “The benefit is that we will have a very targeted therapeutic approach, patients won’t have any side effects, and hopefully they will be more potent and effective therapeutics.”
An oncolytic virus works to destroy cancer in multiple ways, explains Dr. Bell, notably stimulating the immune system and directly killing cancer cells. “[A virus] awakens the immune system which says ‘What is that virus doing there? It shouldn’t be there, I know viruses are bad.’ And the patient’s immune system rushes in to attack the virus and the infected cancer,” he says. “Then the immune system says, ‘This tumour shouldn’t be here either’…and it begins to attack that as well.”
A pan-Canadian clinical trial is currently under way in Ottawa, Hamilton, Toronto and Vancouver, treating 70 cancer patients with some of the team’s products. Initially only solid tumours such as kidney, breast, prostate and pancreatic cancers will be tested – but this is expected to expand as more information becomes known.
With this new funding, Dr. Bell and his colleagues based at centres/universities in Ontario, Quebec and BC will be able to advance understanding of these viruses, develop strategies to make them even better, and bring them closer to reality for patients. Their research will involve genetically modifying various oncolytic viruses and combining them with different drugs and cell-based therapies.
“We’re hoping to see responses, and we’re hoping to see some of these patients have tumours that shrink,” says Dr. Bell. “We’re also going to assess the patient’s immune response to see if the patient is actually developing immunity against their own cancer.”
“We think that at the end of the trial we should be able to say this therapeutic is effective…And we know by working together we will be able to make this happen.”