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In a surprising medical breakthrough, a new HIV patient appears to be in lasting remission after a bone marrow transplant. The case, which occurred in Switzerland, has shaken the scientific community because of the absence of a genetic mutation normally associated with HIV cures.
The story of this 53-year-old man marks a potential turning point in the fight against this disease. But how can we explain such a phenomenon, and above all, what therapeutic avenues does it open up?
7 cases of healing in the world
Worldwide, 7 people (two patients each from Berlin, London, Düsseldorf, New York, City of Hope and Geneva) are considered probably cured or in lasting remission from HIV infection after receiving a bone marrow transplant for the treatment of blood cancer.
But the last patient, Romuald, is the only one to have experienced such remission of HIV following a bone marrow transplant not carrying the CCR5 delta 32 mutation. This rare genetic mutation is known to make CD4 cells naturally resistant to HIV.
A rare and fascinating case of healing
In 2018, this man, who had been infected with HIV since the 1990s, underwent a bone marrow transplant as part of the treatment for aggressive leukemia. This type of transplant, combined with patients with leukemia or lymphoma, has sometimes led to HIV cures in very specific cases. This is usually possible when the marrow donor has a rare mutation in the CCR5 gene, making their immune cells resistant to the virus. However, in this specific case, the patient did not have this protective mutation.
After stopping his antiretroviral treatment in November 2021, tests carried out on him confirmed the absence of a detectable viral load, even after 20 months without treatment. According to the researchers at the Pasteur Institute, responsible for the study, this case constitutes “the first documented sustained remission without the CCR5 mutation“, which challenges conventional theories about HIV cure.
A new path to curing HIV
While this man’s case follows that of patients nicknamed “the Berlin patient” or “the London patient”, all cured thanks to bone marrow transplants, this new remission is different. Indeed, the absence of a protective genetic mutation in this case deeply intrigues experts. As Dr. Asier Sáez-Cirión of the Pasteur Institute explains, this opens up new avenues for us regarding the mechanisms of HIV control by the immune system.
The bone marrow transplant appears to have caused a profound overhaul of his immune system, allowing the body to control the virus autonomously. The challenge now is to understand how this balance was established. Scientists point out that the virus could still be present in the body, but it would be unable to replicate.
Hope for new treatments
While bone marrow transplantation remains a difficult and risky treatment, these results could guide research towards new approaches to treat HIV without transplantation, by directly targeting the immune response.
However, it is important to remember that this method cannot be generalized to all patients with HIV. The number of patients in remission after a bone marrow transplant remains extremely small. A bone marrow transplant remains very heavy and risky, unthinkable for the majority of carriers of the virus. To date, only seven cases of potential cure of HIV have been recorded, and all concerned patients who had undergone transplants to treat cancer.
The mystery of mutation-free remission
The fact that this Swiss patient achieved lasting remission without the CCR5 mutation sheds new light on how HIV can be controlled or even eradicated. For the researchers, this suggests that other, as yet unknown, factors are at play. It also revives the idea that the human body could, in particular circumstances, manage to control the virus without the help of the mutations usually studied. While waiting for a proven explanation, the researchers put forward hypotheses:
- The presence of innate immune cells with high anti-HIV potential could counter the possible rebound of the virus from the few infected cells that could remain in the body;
- On the other hand, the immunomodulatory treatment that this patient receives to control graft-versus-host reactions, experienced repeatedly since the transplant, could help to avoid viral reactivation;
- Ultimately, these graft-versus-host reactions may have led to such effective elimination of the viral reservoir that the CCR5 delta 32 mutation is no longer necessary because no virus capable of multiplying would remain in the body. These hypotheses open important avenues of research aimed at the remission of HIV infection.
Researchers hope this case will lead to advances in understanding the mechanisms of HIV immunity. But much more research is needed to determine whether these new insights can lead to more accessible and less invasive treatments for the millions of people living with the virus around the world.