It’s not often that researchers discover the potential for a whole new way of attacking cancer, but on Tuesday, researchers at the Princess Margaret Cancer Centre announced they may have done exactly that.

The team announced they are developing a new class of drugs they hope will slow the growth of a number of forms of cancer.

The team said there are three aspects that made their discovery unique:

  • Their drug is not designed to kill cancer cells, but rather to stop them from reproducing
  • It’s the first drug to target a key enzyme that allows cancer cells to divide
  • Their research received no pharmaceutical company funding

The drug the team has been working on over the last 10 years is designed to target an enzyme known as PLK4, which plays a key role in cancer cell division.

Dr. Mark Bray from the Campbell Family Institute for Cancer Research says while the enzyme isn’t new to scientists, understanding its exact role in cancer growth is.

“While the enzyme had been known before, very little had been known about its specific role and putting a finger on it as a potential vulnerability came out of broader research,” Bray told CTV’s Canada AM Wednesday, referring to work led by Dr. Tak Mak, director of the Princess Margaret Cancer Centre in Toronto.

Bray believes what his team has found is “hugely significant” and could offer a completely new approach to slowing cancer growth.

“It’s odd that in this day and age, when we’ve sequenced the genome and there have been many, many targeted drugs developed, that a drug enters the clinic targets something that’s never been drugged before,” he said.

“This represents a vision of Tak’s, of finding a new way of looking at cancer, attacking cancer at a completely different angle. So it’s an exciting opportunity.”

Unlike conventional chemotherapy drugs which attack all fast-dividing cells -- cancerous or not – this new drug class would target cancer cells, leaving healthy cells alone.

Dr. Philippe Bedard, a medical oncologist at Princess Margaret Cancer Centre, says what makes cancer cells different is that they have many more than the standard healthy cell’s 46 chromosomes.

“In many types of cancers, we’ve known for some time that there’s a process call aneuploidy in which cells divide and develop different pieces of chromosomes. And we think that’s very important for their ability to resist treatment,” he told Canada AM.

“This enzyme, we think, is important in that process and this is the first drug that is targeting that process.”

In lab experiments on mice that were implanted with human breast and ovarian tumours, the new drug appeared to inhibit the growth of tumours. The team believes it could also be effective on many other types of cancer, including colorectal, lung, pancreatic and prostate cancers, as well as glioblastoma and melanoma.

The research team has submitted a 4,300-page application to the FDA and Health Canada asking to begin clinical trials in humans. They hope to have approval by the fall and to start their study by year’s end.

The first testing phase would assess the safety of the drug in around 30 volunteers with breast or ovarian cancer. That testing should help determine how strong a dose can be tolerated and watch for side effects. If that pahse finds the drug's benefits outweigh its risks, the next phase of testing would assess its effectiveness.

Bedard says the clinical trials would likely involve patients with cancer that can’t be removed with surgery or treated with medication or radiation.

There are still many questions to be answered about the drug. Buti If all goes well, the team estimates it could be less than 10 years before the drug is approved for widespread use.

The team also promises that it has other compounds in early development aimed at targeting other newly discovered proteins.