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Siblings with progressive vision loss have renewed hope for the future thanks to a breakthrough gene therapy treatment

Written by Idella Sturino

When Michael and Cassidy VanOverbeek were growing up, daily life for the brother and sister was different than it was for their peers. But it would be years before they understood why.

“I have always had trouble seeing at night but I thought it was normal — that everyone would find everything black,” says Michael. “I would be thinking, how do people navigate through this? They must be really good at it. Then when I was diagnosed, I realized okay, this is not normal.”

Michael, 21, has a rare and aggressive form of retinitis pigmentosa — a genetic disease which causes progressive vision loss. His sister Cassidy, 19, has also been living with the same condition since birth.

Both Michael and Cassidy have what doctors describe as poor vision. This makes everything from seeing at night, to crossing the street unassisted, to recognizing people’s faces extremely difficult.

“It’s a devastating disease for patients and their families,” says Sunnybrook ophthalmologist and vitreoretinal surgeon Dr. Peter Kertes. “They typically have an onset of symptoms early in childhood and usually by young adulthood they’re pretty disabled.”

Today, however, Michael and Cassidy are turning over a new page thanks to a ground-breaking gene therapy treatment called Luxturna, offered for the first time at Sunnybrook.

Luxturna is designed to treat a type of retinitis pigmentosa known as Leber’s congenital amaurosis, specifically one that is caused by mutations in the RPE65 gene. The drug helps replace the faulty gene with a healthy one to slow vision loss and restore some vision.

“It’s transformative,” says Dr. Kertes.

For Michael and Cassidy, it has been a long and difficult road to get to this point.

It took several years for doctors to diagnose the siblings. Even then, Cassidy says, as a child it was hard to comprehend the impact the disease was having on her.

“I just remember being frustrated because I couldn’t do things as well as other kids,” she says. “Something could take me a year to get good at whereas it could take someone else a month.”

Cassidy says it was challenging to get adequate support and understanding from some members of her community in Cornwall, Ontario. For instance, while teachers provided accommodations to help with things like reading and writing, she says they sometimes seemed to do so reluctantly.

“If they found out they had to make larger print they would kind of sigh and roll their eyes,” she says. The thing with (this condition) is I don’t look disabled. I look like I can see just fine.”

For Michael, the challenges continued in college when he enrolled to study game development. Having to attend classes online due to the pandemic, combined with having to advocate for accommodations, meant it was a constant uphill battle.

“I failed a lot more courses than I am proud to admit,” he says.

Knowing the toll retinitis pigmentosa takes on people is what motivates Sunnybrook’s team of pharmacists involved in providing the unique gene therapy treatment.

“It’s life-changing therapy,” says Pharmacist Jonathan Shloush.

It’s also, he says, one that requires a military-like approach to logistics coordination. More than a dozen pharmacists, pharmacy technicians and other staff spent months working to ensure the drug would be ready for patients like Michael and Cassidy when the time came.

“Literally mapping out things A to Z — all these processes needed to be worked out,” Shloush says.

The drug had to be kept at a temperature of at least -65C during shipment from Germany. Once it reached Sunnybrook, special arrangements were made to keep it in cold storage until one hour before surgery. Only then could Jodi Wood, a registered Pharmacy Technician specially trained in handling Luxturna, take it out of storage and wait for it to thaw in a sterile ‘clean’ room, before preparing it for Dr. Kertes to administer.

“It’s definitely unique,” Wood says of the process. “It was exciting because gene therapy is new for us to be handling so that was actually quite interesting.”

For Shloush, the team effort involved in this kind of treatment goes to the heart of what Sunnybrook does best.

“It’s truly a collaborative effort,” he says. “It really does align fully with what Sunnybrook stands for in terms of teams coming together to care for patients.”

Dr. Kertes echoes that sentiment, pointing out that collaboration across Sunnybrook’s various departments as well as with colleagues at SickKids Hospital was key.

In February, the Ontario government said it would fund Luxturna treatment — which costs more than $1 million for both eyes — for a number of patients at SickKids and Sunnybrook. The announcement was welcomed by patients and their families, as well as groups such as Fighting Blindness Canada.

Michael and Cassidy say they are grateful the treatment is now available to them. They will continue to receive follow-up care in the coming months from Dr. Kertes and their care team. And they are hopeful about what the future now holds.

“I’m hoping I can get a part-time job and maybe see better at night so I can hang out with friends past five p.m.,” says Cassidy. She adds she would like to pursue a career as a therapist one day.

And for Michael?

“I am looking forward to becoming more independent,” he says. “Being able to go into a bank or a store and actually see what’s in the building, shop for myself, do my own banking. My ultimate goal is to be able to start my own game development studio.”

Dr. Kertes, for his part, hopes this kind of gene therapy will soon become more commonplace.

“I feel like I’ve been waiting my whole professional lifetime for something like this,” he says. “This is the most exciting thing to come along in a generation. To talk to these patients after they’ve had their treatment and to hear their stories, it’s hard not to get emotional.”

About the author

Idella Sturino

Idella Sturino is a Communications Advisor at Sunnybrook. She has a passion for storytelling and public engagement and brings two decades' worth of expertise as a former journalist to the role.