A new class of experimental drugs being used to treat some patients with melanoma, a potentially fatal type of skin cancer, can dramatically improve survival rates, early studies show.

According to Dr. David Hogg, an oncologist at Toronto's Princess Margaret Cancer Centre, early results from Anti-PD-1 trials suggest the immunotherapy drugs can potentially increase survival rates by more than 80 per cent at the two-year mark.

"We are seeing early data that suggest survival at two years is over 80 per cent," Hogg told CTV News in an interview. "That is an extraordinary change."

Typically, the survival rate for melanoma patients, especially in cases where the cancer has spread to other organs, is about one year or less.

"For those of us in the community this is nothing short of earth shattering," Hogg said of the drug's potential to extend a patient's lifespan.

He cautioned, however, that the drug still needs to be tested in larger trials.

How Anti-PD-1 works

A new class of anti-cancer therapies, Anti-PD-1 drugs work by helping the immune system recognize and attack cancer cells. The drugs break down a cancer cell's protective shield, allowing a patient's immune system to kill the cancer.

For skin cancer patients like Trent Krajaefski, the anti-cancer immunotherapy has helped to steadily improve his health.

After finding out that his cancer had spread to his lungs and brain, Krajaefski started an Anti-PD-1 treatment. About a year-and-a-half later, his doctor said his tumours have significantly decreased in size.

"All of the tumours that were originally found are shrinking significantly. We're down to measurements in millimetres as opposed to centimetres," Krajaefski told CTV News.

"So things are excellent for me and the results confirm that."

The efficacy of immunotherapy as cancer treatment may not be restricted to just skin cancer. Studies have been launched to examine how it can be used to fight lung and kidney cancers, as well as difficult to treat brain tumours.

With a report from CTV News' medical specialist Avis Favaro and senior producer Elizabeth St. Philip