A drug that corrects a genetic mutation in some cystic fibrosis patients has shown remarkable results, but a high price tag in the hundreds of thousands of dollars puts it beyond the reach of most Canadians.

The drug is called Kalydeco and it is the first drug that fixes a genetic mutation found in around four per cent of patients with CF -- a fatal genetic disease that affects the lungs and digestive system.

According to Cystic Fibrosis Canada, there are around 100 patients in the country that have the G551D mutation of CF, which can be treated with Kalydeco. Patients who have been treated with Kalydeco have shown improved lung function and manage to gain weight.

The national drug review panel recently ruled that the drug is very effective and provinces should be covering the cost to make it accessible for patients, but not at its current price tag of around $300,000 per year.

Vancouver CF patient Shan Ree used to spend a lot of time in hospitals with lung infections brought on by the disease. But since starting on the drug three years ago as part of a clinical trial, the 9-year-old’s condition has improved immensely.

“I feel light when I breathe in. I can breathe through my nose… it feels good,” she said.

Her mother, Wendy Ree, said her daughter’s improvements have been amazing. “She has more energy. She doesn’t have dark circles under her eyes and the fact that she hasn’t been in the hospital… almost three years which is amazing,” she said.

Shan Ree is able to take Kalydeco through her family’s private insurance, but other families in the same situation can’t afford the drug.

Ontario CF patient Madi Vanstone has missed two months of school so far this year because of lung infections. Recently the 11-year-old spent 10 days in hospital.

“It makes it hard to breathe and I get into the hospital a lot because I just get so sick that I can’t stay at home,” she said.

Even with the help of multiple medications and inhalers each day, her mother says Madi Vanstone’s lung function has dropped by 30 per cent since last January.

She could also be treated by Kalydeco, but her family can’t afford it. Her mother says it’s been difficult to watch her daughter’s health decline.

“It’s extremely frustrating to have something that could make such a huge impact on so many, and to have it so unreasonably unaffordable that I don’t know very many people anywhere that would be able to afford this drug,” Beth Vanstone said.

Michael Law, a professor of public health at the University of British Columbia, says that as new, more effective medications are developed for rare diseases, there needs to be a discussion about who covers the cost.

CF patients in the U.S. have access to the drug through private insurance plans or through Medicaid. And this year, England, Scotland, Northern Ireland and Ireland all decided to fund Kalydeco for CF patients.

Ireland initially refused to cover the cost of the drug, citing its high price. But the company that manufactures Kalydeco, Vertex Pharmaceuticals Inc., entered into negotiations with the country’s funding agency, resulting in significant savings.

Law said Canadian provinces could enter into similar negotiations.

“Provinces should work together to really push manufacturers, and get those prices down to a more reasonable level, because this drug isn’t going to be the last one that comes forward with a price tag that’s this high,” he said.

In a statement to CTV News, Vertex said that it is “working closely with the provinces and territories across Canada to ensure that those who are eligible can get it as quickly as possible.”

Spokesperson Nikki Levy added that the company has a support program that provides reimbursement and financial aid to eligible patients who meet certain criteria.

“When we set the price, we thought about how well this medicine works for patients, the cost and time it took to develop and our continued investment in the research and development of other potential new medicines for CF,” she said.

According to Cystic Fibrosis Canada, Kalydeco is now being considered by the pan-Canadian purchasing alliance – an alliance between all the provinces, with the exception of Quebec, to negotiate the prices of drugs, medical supplies and equipment. Alberta will be leading the negotiations with Vertex.

With a report from CTV News’ Medical Correspondent Avis Favaro and producer Elizabeth St. Philip