A Toronto man could become the 1st Canadian cured of HIV thanks to rare bone marrow treatment

Dr. Sharon Walmsley was a medical houseman during the betimes years of the HIV/ acquired immune deficiency syndrome epidemic in the ‘80s. 

“I used to pass every dark sitting on someone's bed watching them die,” she said, recalling the palpable sense of fear in the hospital. 

Having to tell patients they were dying — to tell their parents they would lose their child — almost made her give up on medicine, she said. 

Known as the “Toronto patient,” the 62-year-old man was diagnosed with HIV in 1999 and started antiretroviral therapy to suppress his virus levels. 

In 2021, he developed life-threatening blood cancer that required chemotherapy and a bone marrow transplant — making him a rare candidate for an expensive and risky treatment that is considered to have cured between five and 10 others worldwide of HIV.

Though it’s hailed as a significant treatment advancement, the perfect storm of circumstances that must collide to qualify for it — developing HIV and blood cancer and matching with one of the very limited number of bone marrow donors who have an exceptional genetic mutation — make it something that will benefit only a few. 

But this case, and those like it, have sparked hope that it could be the catalyst from which a broader cure can be created. 

For the Toronto patient, it meant “not only has he survived this cancer, but now he appears to have eradicated his HIV,” Walmsley said.

He stopped taking antiretroviral therapy in 2025 and as of April 2026, his HIV levels were undetectable. If things continue like this for roughly another 20 months, he’ll be considered cured.

While there’s no “magic number” of years that define when a patient is free of HIV, Walmsley said, “if you go out to three years, some mathematical modelling suggests that you’re probably cured at that point.”

Walmsley said her patient’s apparent recovery marks an incredible achievement but warns this type of treatment is not recommended for the vast majority of HIV patients.

Bone marrow transplants and chemotherapy are invasive and carry risk, Walmsley said. Numerous studies estimate that between 10 and 20 per cent of bone marrow transplant patients die from complications related to the procedure, though more recent research funded by the U.S. National Institutes of Health suggests the mortality rate is now on the lower end of that scale. Meanwhile, antiretroviral treatments are incredibly safe, effective and widely available in Canada.

It is only this rare combination of a patient with HIV and blood cancer who creates a unique opportunity to try this type of treatment, says microbiology and immunology professor Eric Arts.

Toronto man poised to become 1st Canadian cured of HIV | Hanomansing Tonight

In the Toronto patient’s case, he received donor cells containing a rare genetic mutation called “delta-32” in the CCR5 gene. The mutation prevents immune cells from creating the receptor protein that makes them vulnerable to HIV. 

Then, his immune system was eradicated through a process called myeloablation or myeloablative conditioning, which uses high-dose chemotherapy or total body radiation treatment to destroy bone marrow cells. 

“You get rid of all of their immune cells, and you transplant them with these stem cells that  reconstitutes, redevelops their immune system,” Arts said. 

For someone living with HIV and a blood cancer, giving them virus-resistant cells is the only treatment option for both conditions, but it’s not a method a healthy HIV patient would be offered because of the risks involved. 

This particular treatment is rare not only because of the risks to the patient but also, Arts said, because only one to two per cent of people of European descent have two copies of the mutated CCR5 gene. Once donors are identified, their cells must be transported quickly to the matching recipient for the transplant to be successful, all of which adds to the complexity.

The donor for the Toronto patient was found using German and U.S. Bone marrow donation registries. Canada currently doesn’t have such a registry, something Walmsley said she hopes will be developed.

Though this targeted treatment would not work — or be available — for many, Walmsley said, she hopes it helps scientists to find less invasive ways to eliminate the virus or prevent it from entering cells.

“Is it immunotherapy? Is it a gene therapy? Is it drugs? I think we have to investigate all of these different pathways,” she said, referring to building upon future treatment options. 

Arts says he’s happy Canada has achieved this milestone but wants to see HIV solutions developed that are less costly and less complicated.

“It's not something that's easily adopted, certainly not around the world, in low income settings, where the burden of HIV is the greatest,” Arts said. 

This treatment costs around $300,000 in Canada, according to Arts and other research. That includes finding a donor, getting the transplant, the costs of being in hospital and for extended care. 

By comparison, one treatment option offered in Ontario costs about $1,400 a month and is covered by most insurance plans, according to a Toronto pharmacy. 

Of the more than 65,000 Canadians living with HIV, 85 per cent are diagnosed and receiving treatment, according to the Canadian AIDS Treatment Information Exchange.

Right now, HIV rates are rising in Manitoba, with the province declaring a public health emergency to increase traditional and non-traditional forms of testing and to raise awareness about the spread.

Manitoba’s chief public health officer, Dr. Brent Roussin, said the province has the highest rates of HIV in Canada. In 2024, the province reported a roughly 3.5 times higher rate than the rest of the country.

At 29, Adam Castillejo said he was told he would live for just five to 10 years if he didn’t seek treatment. It was 2003 and he had been diagnosed with HIV. 

“It felt like the world was ending for me,” he said. 

Then, he became known as the “London patient” — the second person in the world considered to be cured of HIV.

“I felt overwhelmed with joy, since you have a second chance at life, and to make the best out of my life.”

Now he’s happy to welcome the Toronto patient to the small group of people who have been cured of HIV, though he said he is optimistic more will follow.

“Please stay hopeful because scientists are working around the clock to find a cure that’s feasible for everybody,” Castillejo said.

Sharon Walmsley and Adam Castillejo interviews produced by Theo Lemarchandel and Cassie Argao

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