Dusseldorf patient recovered following bone marrow transplant with rare mutation ‘known to prevent HIV from entering cells and therefore protect against infection’
The third to be cured of HIV. Researchers from the IciStem consortium, which includes a team from the Institut Pasteur, revealed on Monday a new case of HIV recovery after a bone marrow transplant. The one who is called the “Dusseldorf patient” no longer shows any trace of the virus in his body four years after treatment, according to work published in Nature Medicine.
Only two similar recovery cases have been described so far in scientific publications: the patient from Berlin in 2009 and the patient from London in 2019.
· What treatment did this patient receive?
It all started in 2008, when a medical team from Düsseldorf (Germany) diagnosed a patient with an HIV infection. The man began antiretroviral treatment in 2010 “which allows him to control the infection and reduce the amount of virus to undetectable levels in the blood, like most people on treatment”, emphasizes the Institut Pasteur.
But in 2011, this patient was diagnosed with leukemia, “that is to say a cancer of the cells of the immune system localized in the bone marrow”. He was initially treated with chemotherapy but was due to receive a stem cell transplant in 2013. “A donor carrying the CCR5 delta-32 mutation” is then sought, because this mutation is known to prevent the entry of HIV into cells.
“We know that the HIV virus targets cells of the immune system,” explains virologist Asier Sáez-Cirión, co-author of the study. However “during a bone marrow transplant, the patient’s immune cells are thus completely replaced by those of the donor, which makes it possible to eliminate the vast majority of infected cells.”
In 2018, the medical team no longer detects the presence of HIV in the patient’s body, so the latter stops his antiretroviral treatment against the virus, even if he remains under surveillance. And 44 months later, still no trace of the virus has been found in his analyzed tissues.
“Even if we could not analyze all the patient’s tissues to definitively rule out the presence of HIV in the body, these results indicate that the immune system did not detect the virus after the interruption of treatment”, specifies Asier Saez-Cirión.
· What is the mechanism behind this healing?
The patient studied received stem cell donations before being cured of HIV, comprising a mutation of the CCR5 molecule. It is the latter that allows the entry of HIV into the cells.
“Located on the surface of white blood cells, CCR5 regulates host immune responses against pathogens”, explains Inserm“but, a victim of its own success, it also serves as an anchor for HIV to infect immune cells, thus contributing to the development of AIDS”.
However, some people, less than 1% of the world’s population, have a mutation of this gene: the CCR5 delta 32 mutation, which “is known to prevent the entry of HIV into cells and therefore protect against infection”, writes the Pasteur Institute.
The patient from Düsseldorf received a transplant with this mutation, like the patient from Berlin and the one from London before him, following which they eliminated the HIV.
· So we found a safe treatment for HIV?
Stem cell transplant procedures, however, remain exceptions. In the three cases of remissions described, they were launched because the patients suffered “from a hematological disease” for which “no other therapeutic alternative exists”, explains the Pasteur Institute. In other words, this treatment was not launched to fight against HIV but against another disease.
In addition, this type of transplant is particularly heavy and can be very risky for the patient, which is why it remains exceptional and is used as a last resort.
Finally, since less than 1% of the general population carries this protective HIV mutation, it is very rare to find a marrow donor who is both compatible with the patient and carries this mutation.
“In the end, it is an exceptional situation when all these factors coincide so that this transplant is a double success in healing, leukemia and HIV”, says Asier Sáez-Cirión.
· What use is this discovery all of a sudden?
The result of this study “teach us a lot about the healing mechanisms of HIV”, underlined this Tuesday on France Info l’infectiologue Yazdan Yazdanpanah.
Several gene therapy trials are also underway, to find a way to introduce the valuable CCR5 mutation into people and make them more resistant to HIV. Vaccines are also under study and if there have been failures, research is moving forward. Last November, immunologist Yves Lévy announced that his vaccine candidate had passed experimental phases 1 and 2.
If today there is no means of curing HIV on a large scale, treatments for the disease, to be able to live with this virus have greatly developed, “antiretroviral treatment is currently the best therapeutic alternative”, writes such as the Pasteur Institute.
There is also a drug allowing you to avoid contamination (the Prep) and another to be taken within 48 hours of a possible infection (TPE).
The best way to fight against HIV still remains prevention today: it is essential to protect yourself during sexual intercourse, to test yourself regularly to be taken care of quickly. According to Unaids“38.4 million people were living with HIV in 2021” and 1.5 million were newly infected in the same year.