This is news that opens up potential avenues for research. A man referred to as “the patient from Geneva” is in long remission from HIV after receiving a bone marrow transplant that does not have a mutation known to block the virus. His case was presented Thursday July 20 in Brisbane, ahead of the International AIDS Society conference which will open on Sunday in Australia.
Before him, five people have already been considered probably cured of HIV infection after receiving a bone marrow transplant. The cured patients all had a very particular situation in common. They were suffering from blood cancers and had benefited from a stem cell transplant which deeply renewed their immune system.
But, each time, their donor presented a rare mutation of a gene called “CCR5 delta 32”, a genetic mutation known to prevent the entry of HIV into cells. For the “patient from Geneva”, the situation is different: in 2018, to treat a particularly aggressive form of leukemia, he benefited from a stem cell transplant. But this time, the transplant came from a donor who did not carry the CCR5 mutation.
Thus, unlike the cells of other people considered cured, those of the donor person theoretically allowed HIV to reproduce. However, the virus remains undetectable twenty months after the interruption of antiretroviral treatment in this patient followed at the University Hospitals of Geneva, in collaboration with the Institut Pasteur, the Institut Cochin and the international consortium IciStem.
His antiretroviral treatment was gradually reduced and definitively stopped in November 2021. And the analyzes carried out during the twenty months which followed the cessation of treatment detected neither viral particles, nor an activatable viral reservoir, nor an increase in immune responses against the virus in the organism of this person. The scientific teams cannot exclude that the virus still persists, but they consider that this is a new remission of the HIV infection.
An “encouraging” remission
Other patients with HIV had benefited before him from marrow transplants without the famous protective mutation. But “The virus reappeared after a few months”says Asier Saez-Cirion, head of the Viral Reservoirs and Immune Control Unit at the Institut Pasteur. “We consider that when we exceed the twelve months of undetectable virus, the probability that it will remain undetectable in the future increases significantly”he adds.
How to explain such a phenomenon in this patient? Several hypotheses are put forward. “In this specific case, perhaps the transplant eliminated all the infected cells without the need for the famous mutation.says Mr. Saez-Cirion. Or perhaps his immunosuppressive treatment, required after the transplant, played a role. »
This long remission is “encouraging” but “a single virion [une particule virale infectieuse] can lead to a rebound of the virus”, warned Sharon Lewin, president of the conference of the International AIDS Society. This patient “will need to be watched closely over the next few months, if not years. The likelihood of a rebound is impossible to predict”he added.
If these remissions nourish the hope of one day overcoming HIV, a bone marrow transplant remains a very heavy and risky operation: it is not adaptable to most carriers of the virus. These cases nevertheless open up new avenues of research, such as the possible role that immunosuppressive treatments could play.
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“It also encourages us to continue to study certain cells of innate immunity” [la première barrière de défense vis-à-vis de divers agents pathogènes]likely to influence the control of the virus, adds Asier Saez-Cirion. “We know that we are not going to transplant all patients who have HIV, but this opens doors to try to obtain lasting remissions in the absence of a transplant with a mutation”underlined Thursday at a press conference Professor Alexandra Calmy, head of the HIV unit within the University Hospitals of Geneva.
The “Geneva patient”, who had been living with HIV since the early 1990s, wishes to remain anonymous for the time being. “What is happening to me is magnificent, magical”he simply reacted in a press release from the Institut Pasteur.