An inspirational Fort McMurray firefighter and former MMA competitor died Sunday, after a long fight with cancer.

He battled cancer for several years before passing away at the age of 27.

Bo Cooper, known as Unbreakable Bo, was first diagnosed with acute lymphoblastic leukemia (ALL) at the age of 20.

He was treated successfully twice, but in 2015, Cooper learned that the bone marrow transplant he had a year earlier hadn’t worked and the cancer had returned.

His only option was an experimental treatment, known as CAR T-Cell therapy, that wasn’t available in Alberta.

The therapy involves sampling a patient’s immune cells and modifying them to recognize and kill the cancer. The altered cells are then grown in a lab before being administered back into the patient.

The U.S. government covers part of the costs, but the treatment still comes with a price tag between $500,000 and $900,000.

In December, 2015, the Alberta provincial government said it wouldn’t cover the cost of his treatment.

Bo’s story touched the hearts of so many people from around the world who came to his aide, raising more than $300,000 so he could go to the U.S. for treatment.

“You saw, not only from Fort McMurray, but people pouring in donations from across Alberta and across Canada and the world just really touched by the story of how he was fighting,” Tyran Ault, Regional Municipality of Wood Buffalo Councillor, told CTV News.

In April, Cooper’s family posted on Facebook that his cancer was in remission after the treatment.

But doctors later found that Bo’s cancer was back and he would never reach full remission.

Four weeks ago he got an infection.

“If there’s one way to look at it, it is that it opened a lot of eyes in terms of leukemia and the battle that these individuals have to go through in fighting this awful disease,” Ault said. “If it’s raised a little bit of awareness, I think that’s part of what the Cooper family and the Fort McMurray Fire Department and their friends really wanted to do.”

While Bo is now dead, Canadians are marking his legacy on a Facebook page which is flooded with messages of love and support.

There is even talk of a more permanent way to remember him.

“I'm sure a recommendation will be coming forward through them for some kind of naming the way that Bo touched the entire community, you need to have some kind of lasting legacy,” said Ault.

With a report from CTV News Edmonton