Hope for Pancreatic Cancer Therapy

"The reason we're so excited about these viruses is that they take advantage of the same things that the tumour uses to become a really good tumour: they exploit those for therapeutic benefit."
"It was the complete opposite of what we expected [result of study of cell types in pancreatic cancer]. Something about the way they interact makes them much more sensitive to virus infection. So, potentially, virus infection could be a great treatment for pancreatic tumours."
"We think this is an opportunity to try something different. And I think pancreatic cancer patients would think the same thing: that it's worth trying because right now current therapies are not working."
Dr. John Bell, senior scientist, Ottawa Hospital Research Institute

Julie Oliver/Ottawa Citizen    Dr. John Bell of the Ottawa Hospital's Cancer Centre has pioneered the use of viruses to treat certain types of cancer.

Dr. Bell is speaking of a study he co-authoried with post-doctoral fellow Dr. Carolina Ilkow, along with other scientists, a study that was just recently published in Nature Medicine, that describes experiments whose purpose was to discover a finer understanding of pancreatic tumours and how they form and interact with the body's cells. The tumours are constructed of a complex network of stromal and malignant cells.

Normally the body's stromal cells aid in the maintenance of body tissue. They are susceptible, however, to being co-opted by cancer cells in the promotion of tumour growth. Once researchers isolated the cell types, they studied their interaction with each other and with viruses. And that led to the discovery that the relationship between stromal and malignant cells set them up to be vulnerable to viral infection.

The theory was tested with embedding a modified virus -- from Brazilian sandflies -- with the growth factor secreted by stromal cells, so very present in pancreatic tumours. The virus that had been engineered for the purpose proved itself "a more potent killer of cancer cells" than did the original Maraba virus. The virus resulted in "complete tumour regression" in some laboratory mice, according to the study.

Pancreatic cancer causes the death of around 4,400 Canadians annually. People diagnosed with pancreatic cancer are given a five-year survival rate of a mere six percent. This represents the lowest survival rate among all common cancer types, and it has seen no improvement in the past four decades. The only 'cure' remains major surgery, performed only if the tumour has not spread beyond the pancreas.

In 85 percent of cases, the cancer is not detected in an early enough stage to make surgery feasible.

Furthermore, pancreatic cancer is resistant to conventional treatments like chemotherapy and radiation in view of the unusual architecture of the tumours with their heavy concentration of stromal cells which protect the tumour, promoting its growth. But the very same biological process that makes pancreatic tumours so tough, also serves to make them vulnerable to attack by the engineered viruses.

Dr. Bell is known worldwide for his leadership in the use of virus-based cancer therapies. He is also scientific director of BioCanRx, representing a network of scientists involved in accelerating promising cancer treatments from the laboratory on to clinical trials. He does caution though that clinical trials are several years into the future, while holding out hope they may lead to a more effective cancer treatment for pancreatic cancer.