Ioan Siara
Ioan Siara receives his weekly infusion of the drug tebentafusp to treat metastatic uveal melanoma. (Photo: UHN)

Ioan Siara says he doesn't mind the drive.

It's about 740 kilometres – round trip – from his home in Windsor, Ont. to the Princess Margaret Cancer Centre. But the retired dentist says he likes to get behind the wheel.

"I've done it now for almost four years," Ioan says of weekly trips to the centre.

Sometimes he drives up with his wife. Occasionally, he stops to visit friends or family.

"With the COVID situation, this was the only outing that we had for some time," he says.

These are trips Ioan is happy to make because they allow him to access a new treatment, which has stabilized growth of his metastatic uveal melanoma. It's something he didn't think was possible when he was diagnosed in 2017 – 15 years after he lost his left eye to the cancer.

Prognosis after recurrence of the rare illness is not good and there are few treatment options.

At the time, doctors gave him a year and a half to live.

"My family prepared a very nice Christmas party, the whole family was present at a cottage up north close to the Muskoka," he says. "We were thinking that that would probably be my last.

"Well, I've made three more Christmases, including this one."

Shortly after his diagnosis, Ioan was enrolled in a stage three study at PM looking at the use of the drug tebentafusp to treat metastatic uveal melanoma.

The drug had shown promise in an earlier international study which included patients with melanomas, including metastatic uveal melanoma. This latest research focuses exclusively on those patients with the disease.

Thus far, his personal results have been encouraging, Ioan says.

"They call me the king of the clinical trial," he says, laughing about the light-hearted ribbing PM staff have given him about his positive response.

"You could say I'm very happy with it."

Dr. Marcus Butler
"We've specialized in this rare cancer, so we're the leading Canadian centre for uveal melanoma treatment," says Dr. Marcus Butler of the Princess Margaret. "We have made a substantial contribution to this international clinical trial." (Photo: Courtesy Marcus Butler)

Dr. Marcus Butler, clinician-investigator at the Princess Margaret and a co-author of the study, said the findings have the potential to "change the paradigm" when it comes to treatments for metastatic uveal melanoma.

"Nothing has ever worked to treat this rare cancer," he says. "Now we have something that has greatly improved survival. That's very important."

The study, which was published in the New England Journal of Medicine earlier this fall, has shown that tebentafusp has increased what are currently low survival rates for people with the illness. Read the study.

Out of a total group of 378 patients which were randomly assigned to either tebentafusp or one of two other medications, the overall one year survival was 73 per cent compared to 59 per cent in the control group.

The researchers also found that progression-free survival was significantly higher in the tebentafusp group than in the control group – 31 per cent versus 19 per cent at the six-month interval.

Dr. Butler says the work is even more important because of how little study has been done on metastatic uveal melanoma treatments.

"As it turns out, even with rare diseases proper collaborations can result in vital progress," he says.

Dr. Butler says the rarity of the cancer has actually been an impediment to studying it, with small concentrations of patients treated at disparate centres, making large-scale research difficult.

It's the kind of work best suited to the Princess Margaret.

"We've specialized in this rare cancer, so we're the leading Canadian centre for uveal melanoma treatment," he says. "We have made a substantial contribution to this international clinical trial.

"Because of our comprehensive program with ocular oncology, radiation and medical oncology, we were able to provide this option to our patients."

Dr. Butler cautions that despite this initial success, this treatment won't work for all patients because it responds to each person's unique immune system. Further work will need to be done to expand compatibility for more patients, he says.

"We have to screen folks to see if they're eligible for tebentafusp," he said. "But if their immune system 'speaks the right language', they can use this drug."

Dr. Butler says outside of this ground-breaking work, further research is being conducted by Drs. Tak Mak and Naoto Hirano to expand patient compatibility to immunotherapy treatments.

Ioan says he is glad to have taken part in the study and he's hopeful that it can lead to refinement and possible broader use for other patients. He also hopes the treatment can one day be provided in pill form so he doesn't have to make the long weekly journey from his home to the cancer centre.

But Ioan says the study has given him good quality of life and importantly, more time. Time to enjoy his family and grandchildren, and pandemic allowing, perhaps time for some car trips to places other than PM.

"We would love, both me and my wife, to be able to enjoy our adventure a little longer," he said.

This work was funded by Immunocore.

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