A Toronto man could soon join a small club of people in the world considered cured of HIV following a bone marrow transplant to treat cancer that left the immunodeficiency virus in remission.
The 62-year-old man, identified by the health officials only as the “Toronto patient,” had developed acute myelogenous leukemia in 2021 and underwent a bone marrow transplant at University Health Network’s Princess Margaret Cancer Centre.
The procedure involved donor stem cells that were selected because they contained a rare genetic mutation called “delta-32.”
According to the UHN, Unity Health Toronto and University of Toronto, the CCR5 gene encodes a protein on the surface of human immune cells that HIV enters and infects. Those with the delta-32 mutation in the CCR5 gene don’t make the receptor protein, making them resistant to HIV infection.
“One per cent of people of European ethnicity have bone marrows that are resistant to HIV infection,” said Mario Ostrowski, a clinician-scientist at St. Michael’s Hospital. “A bone marrow transplant from these donors can provide a potential cure.”
In the case of the Toronto patient, that appears to be exactly what happened. The case was presented Saturday at the Canadian Association of HIV Research Conference in Winnipeg.
Dr. Sharon Walmsley, director of the HIV clinic at UHN, said it’s a big change for the man.
“This person now has an immune system that cannot be affected by HIV,” Walmsley said. “He is quite amazed by all of this… When we told him that we believe him to be cured, he was pretty astounded.”
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According to the hospital groups, the man was first diagnosed with HIV in 1999 and has been living with the virus for 27 years, taking antiretroviral therapy (ART) to suppress virus levels.
He stopped taking the medication in July 2025 and, as of April 2026, is in sustained remission with HIV levels undetectable. If he remains at this level for two-and-a-half years after stopping ART — approximately the end of 2027 — he will be considered cured of HIV.
The process to find the bone marrow to treat the man’s leukemia meant starting a search for the right match.
Dr. Jonas Mattson with the Princess Margaret Cancer Centre said doctors first checked to see if there was a familial match, which there wasn’t. This prompted a wider search, using global databases to search by tissue type. Doctors can search among 47 million potential donors worldwide using the German and U.S. registries, which accounts for roughly half of all potential donors worldwide.
“The idea is to find as good a match as possible because that will increase the chances that the transplant will be successful,” Mattson told Global News. “So we did that but at the same time since we knew that this patient was HIV positive, we thought that, OK, maybe we can also cure the HIV.”
During their search, doctors found three matching donors who carried the mutated protein.
“The patient’s old immune system was completely gone and replaced by this new immune system and the cancer was gone,” Mattson said. “But the interesting thing is also that this new system was resistant to HIV, meaning that the patient couldn’t get infected or get his cells, the new cells infected.”
While the results are promising, Mattson cautioned people shouldn’t look at this case as a definite method to treat or cure HIV.
Dr. Tommy Alfaro Moya, also at the Princess Margaret Cancer Centre, said it is still a “wonderful” outcome.
“This is not a procedure that you would get to get rid of your HIV,” Alfaro Moya said. “This was a very wonderful, extraordinary outcome of the transplant, but it was not the primary outcome why this individual got a transplant.”
Even though HIV treatment wasn’t the focus, Walmsley said it underscores the need for people to register as donors, which can help lead to further breakthroughs.
Such cases support scientists in their continuing research into treatments to eliminate HIV from a body, she said, which could help also tackle the stigma still present for those with the virus.
“The thing is, this particular mutation is fairly rare and so there really did require an international search in order to be able to find the bone marrow that had the right mutation that would allow this patient to be cured from their HIV,” Walmsley said.
“So it’s really important that we have donors and we have registries so that we’re able to identify the specific bone marrows that we need when patients like these come around.”
—with files from Global News’ Katherine Ward
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