A 62-year-old man in Oslo has become the tenth person to achieve HIV remission following a stem cell transplant, according to a study published Monday in the journal Nature Microbiology.
The patient, who underwent the procedure to treat a blood cancer, has remained free of the virus and off antiretroductory medication for four years.
This latest case follows the precedent set by Timothy Brown, known as the 'Berlin Patient,' who was the first person to be cleared of HIV after a transplant in 2009.
Researchers say these successful outcomes are shifting the scientific consensus from viewing HIV cures as impossible to focusing on how to make the treatment scalable.
"At first, they said cure was impossible, that what happened to the Berlin patient was a fluke," said Javier Martínez-Picado, an investigator at IrsiCaixa and co-leader of the international IciStem consortium.
"But after 10 patients, we know that curing HIV infection is possible, and what we have to see now is how we make it scalable,"
The role of the CCR5 mutation
The procedure relies on a specific genetic mutation known as CCR5 Delta 32, which prevents the virus from entering human cells.
In the Oslo case, the patient received a transplant from his brother, who carries the mutation.
To achieve the transplant, doctors use intensive chemotherapy to destroy the patient's bone marrow, which acts as a reservoir for the virus.
When healthy stem cells from a donor with the CCR5 Delta 32 mutation are introduced, the new immune system is effectively immune to HIV infection.
While the transplant has worked for 10 individuals, researchers note that the method is currently limited to patients with hematological diseases.
Martínez-Picado noted that while 40 people have undergone stem cell transplants for HIV, doctors have been hesitant to stop medication in patients whose donors lacked the double mutation.
Some exceptions exist, such as patients in Berlin and Geneva who achieved remission despite donors without the double mutation, suggesting other biological mechanisms are at play.
Scientists are now investigating gene therapies to manually induce the CCR5 Delta 32 mutation in a broader population of HIV-positive patients.
