October 26, 2018 7:00 am
Updated: October 29, 2018 3:31 pm

Immune system fights cancer: How one boy beat leukemia with new treatment

WATCH: One family shares the story of their son's battle with leukemia.

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Debbie and Richard Lahti look back at their son’s childhood and can’t help but think about what he’s missed out on. Cameron battled with leukemia on and off over the span of eight years; he relapsed twice.

Instead of going to school, playing outside with his friends and going on family vacations, Cameron, who lives in Newmarket, Ont., was in and out of the hospital undergoing years of chemotherapy.

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The chemo was so strong that it deteriorated his immune system. He had one infection after another, lost all his hair and was constantly battling fevers. At one point, he couldn’t walk for a year.

It started when Cameron was three years old. His mother remembers the moment doctors told her he had cancer of the blood.

“It’s one of those things you never forget. Life stopped. Your world freezes. It’s like an out-of-body experience,” Debbie said.

Cameron battled with cancer from the age of three to 10. When he relapsed for the second time in 2016, the end-of-life team at Toronto’s Hospital for Sick Children scheduled a meeting with the Lahti family.

Chemo wasn’t working, and the only other available option in Canada at the time was a bone marrow transplant. Even then, the family had doubts and were worried about the lifelong side effects that would come with the procedure.

Debbie and Richard said they were never ready to give up on their son. Although most options had been exhausted, they started researching alternative treatment methods. That’s when they discovered chimeric antigen receptor (CAR) T cell therapy.

How the therapy works

CAR-T cell therapy essentially re-engineers a patient’s cells in order to be able to recognize cancer and attack it.

“Normally, the immune system is not able to fight leukemia cells. With the CAR-T cell technology, what we do is we take immune cells from the patient, we send them to a lab manufacturing facility, and what they do there is that they genetically modify the lymphocytes — immune cells of the patient — in a way that they now can recognize leukemia cells as something foreign, as something they need to attack,” said SickKids’ Dr. Joerg Krueger.

For the Lahti family, the treatment was only available in the United States in 2016. They had to travel for Cameron to have the treatment administered. But recently, Health Canada approved Kymriah, the first CAR-T cell therapy to become available in the country.

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Krueger said the treatment isn’t for everyone, and as of now, it is only used for cancer of the blood. Patients usually only qualify for this treatment when they have gone into remission and relapsed and when the leukemia has not responded to other more traditional treatments.

To get the treatment, first blood is drawn. Then, through a machine, a patient’s T cells — the white blood cells that are key to immune function — are removed. Those T cells are then modified so they can recognize and attack cancer cells. After that, the modified cells are duplicated in the millions and infused into the patient’s body through blood.

Side effects

Although CAR-T cell therapy has been praised by the medical world for its ability to harness the potential of an individual’s own immune system to target and destroy cancer cells, Krueger says it’s important to be aware of side effects.

When cells are being genetically modified during the treatment, what happens is that a shell of a virus, which is non-harmful, is introduced in order to help the cells recognize leukemia cancer cells, he says.

“One way to do it is to utilize viruses and load them with the gene that you want to introduce and then put them on the cell,” Krueger explained.

Imagine the leukemia cells have an invisible cloak; the new, re-engineered cells have “superpowers” that make them able destroy the cloak and target the cancer.

“They kill every cell that looks like a B cell. And because the leukemia cells look like B cells, they destroy the leukemia,” Krueger said.

But the problem is that those new cells are now killing other cells that look like leukemia cells.

“It destroys the normal B cells, and this is one of the major side effects that we see in our patients, that if the therapy is successful, the patients potentially have a lifelong deficiency in B cells,” said Krueger.

What this means is that the immune system is not able to fight off infections as easily.

“But there is a way to prevent this, and the way to prevent this is by giving antibodies,” he added.

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Patients who undergo CAR-T cell therapy need to get injections once a month for the rest of their lives, Krueger says.

Another thing to keep in mind is that a leukemia patient needs to have enough T cells in their system to be able to receive this treatment. Without the cells, there’s no way of re-engineering them, and sometimes if a patient is too sick then there is a deficiency, says Krueger.

It also takes about three to four weeks to re-engineer the cells.

“Not all patients who we want to give CAR-T cells to actually make it to the infusion,” he explained.

The patient also needs to be under supervision if they do make it to the infusion. Some acute side effects include flu-like symptoms, having trouble breathing and needing to be brought into the intensive care unit, Krueger says. It can be life-threatening.

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All in all, he says it’s important to have a discussion with your oncologist and figure out with the help of a medical team if this treatment is right for you.

“If you get the infusion, you have a likelihood of having no leukemia of 50 per cent after one year. And 50 per cent is much higher (than) if you were to do something else. But it’s also that 50 per cent of the patients, the leukemia will come back,” said Krueger.

As for the Lahti family, they’ve said that this treatment has been the only thing that’s worked for their son. He’s now been in remission for three years. The family says they were finally able to go on a family vacation to England, and Cameron enjoys the simple things in life, like going to school and playing with his friends.

“I take so much pleasure in the smallest things, like hearing him laugh. Feeling him hug me is one of the best sensations. You don’t take simple things for granted,” Debbie said.

WATCH: Potentially life-saving leukemia treatment comes to Canada. Jamie Mauracher reports.

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