An HIV patient is in remission after a unique stem cell transplant. Why it could be a path to a cure
German man's experience could open stem cell donor pool, have promising implications for future HIV cure
A German HIV patient who is in remission following a stem cell transplant from a donor with genes that are partially resistant to the disease is giving researchers new hope that more people could benefit from the treatment.
The first step in a stem cell transplant for people with cancer involves wiping out a patient's immune cells with chemotherapy. When patients also have HIV, these cells can be replaced with transplanted stem cells from rare individuals carrying genes that essentially make them immune to the virus that causes AIDS. Only a handful of people around the world are eligible for this procedure because they must have both HIV and cancer.
According to a study presented by Christian Gaebler of Charité — Berlin University's medical school — the German HIV patient was treated for acute myeloid leukemia with a stem cell transplant in 2015. He stopped taking antiretroviral drugs in 2018 and the virus remains in remission. He's one of just seven people who went into remission from HIV between 2007 and 2023.
In most of these cases, the stem cell donors naturally inherited two copies of the gene called CCR5 delta 32, which confers resistance to HIV. The German patient is the first case where the stem cell donor inherited just one copy of the CCR5 delta 32 gene, according to Gaebler and his co-authors. The research is not yet peer reviewed.
Researchers hope Thursday's virtual announcement at the 25th International AIDS conference in Munich, Germany, could open the door to treatment being offered to more people and have promising implications for future HIV cure strategies.
"Hope is, to me, that a cure is possible, and that's what these cases demonstrate," Sharon Lewin, president of the International AIDS Society (IAS), told reporters.
But the reality, she noted, is that it's rare.
Case could help develop new treatments
Come September, the German HIV patient will have been in remission for six years, according to Gaebler, a length of time that gives the researchers confidence in what they're seeing.
"A healthy person has many wishes, a sick person only one," the anonymous patient said in a statement from IAS on Thursday.
Dr. Marina Klein, a professor of medicine based at Montreal's McGill University, said the man's case could inform how new treatments are developed.
"This case shows that you don't actually need 100 per cent of your cells to be completely resistant," said Klein, who was not involved in the study.
Research suggests that about 1 per cent of Caucasians were measured to have two copies of the resistance gene, while about 20 per cent have one copy. According to experts who study HIV, in individuals with one copy of the gene, the virus progresses slowly if they don't receive antiretroviral treatment, while those with two copies seem to be able to hold the virus at bay altogether.
Lewin, the IAS president, says the German patient's experience "suggests that we can broaden the donor pool for these kinds of cases."
Researchers also hope it could have promising implications for future, more scalable HIV cure strategies.
Klein, who heads up a Canadian clinical trials network for HIV, noted that HIV diagnoses rose almost 25 per cent between 2021 and 2022. She says that makes it more difficult to reach the goal of eliminating the disease.
"People sometimes get impatient, but these incremental bits of learning really are what takes us to the path to cure ultimately," she said.
Questions about availability, cost-effectiveness
Eric Arts, a professor in microbiology and immunology at Western University, studies ways to control HIV.
Though he finds it encouraging that the patient no longer needs to take medications to control HIV, Arts says scaling up the approach so it can be used on other patients has its challenges.
"The actual solution that they're using to really treat leukemia in the first place is not a solution for HIV," Arts said. "To really deal with the [HIV] pandemic overall, it's got to be available to everyone."
When people with HIV take antiretroviral treatment, they're able to live a normal life, Arts said. For them, the low survival rate from a stem cell transplant and cost can't be justified, compared to people with leukemia who have no other option.
As someone who lives with HIV, Jean-Paul Michael manages the disease with antiretrovirals. But when he was first diagnosed, he couldn't afford the medication.
He had been injecting crystal meth for years, but when he began receiving treatment for AIDS-related pneumonia in intensive care eight years ago, a housing stabilization worker offered him affordable housing and tools to rebuild his life.
Stigma around HIV is still very prevalent, says Michael, noting that there's "a lot of recoil when people hear." He now works as an addiction case manager in the emergency department at St. Michael's Hospital in Toronto.
Both Michael and Klein called for antiretroviral medications to be accessible to everyone.
"If we could get to a point where we could actually teach the immune system to handle this virus in a way that didn't need medications … it would be a major advance," Klein said.
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With files from CBC's Meagan Fitzpatrick