Experts have welcomed the announcement that a second patient has achieved full HIV remission after stem cell therapy, but have cautioned against calling it a ‘cure’.
The patient was given a stem cell transplant for haematological disease with cells also known to be resistant to HIV.
The male patient was diagnosed with a HIV‑1 infection in 2003, and went on antiretroviral therapy in 2012. He then developed Hodgkin's lymphoma and was offered a stem cell transplant. Doctors were able to find a donor with genetic protection against HIV‑1, conferred by two copies of the CCR5 Δ32 allele.
CCR5 is the receptor most commonly used by HIV‑1 to enter cells. People who have two copies of the CCR5 Δ32 allele are resistant to the HIV‑1 virus strain that uses this receptor, as the virus cannot enter host cells.
Antiretroviral therapy was continued for 16 months after the transplant, after which regular testing confirmed that the patient’s viral load was undetectable and his immune cells remain unable to express the CCR5 receptor. Full details of the case of sustained HIV-1 remission were published last week in the journal Nature.
It is the second known case of a patient experiencing a sustained HIV remission after a stem cell transplant. The first, known as the ‘Berlin Patient’, was being treated for leukaemia.
The most recent patient has now been in drug-free remission for 18 months – however, experts say it is premature to announced that he has been “cured” and emphasise that this is not a treatment that could be applied to all HIV-positive people.
The doctors responsible for the treatment say it could not be offered to many patients because the chemotherapy used for conditioning prior to stem cell transplant was highly toxic. They say the latest procedure was less toxic than the original Berlin treatment as it did not include total body irradiation.
Rather, it confirms a potential avenue for future research to maintain long-term HIV remission. The case study states: “Replacing immune cells with those that don’t have the CCR5 receptor appears to be key in preventing HIV from rebounding after the treatment.”
Prof Ravindra Gupta of University College London and Cambridge University said: “At the moment the only way to treat HIV is with medications that suppress the virus, which people need to take for their entire lives, posing a particular challenge in developing countries.
“While it is too early to say with certainty that our patient is now cured of HIV, the apparent success of haematopoietic stem cell transplantation offers hope in the search for a long-awaited cure for HIV/AIDS.”
Analyst Dr Christopher Pace, director of infectious diseases at GlobalData, said: “The news does not represent a general path to a cure for other HIV patients; rather, it simply provides more hope to the medical and scientific communities that their efforts towards a cure are not in vain.”
Source: Gupta, R.K., Abdul-Jawad, S., McCoy, L.E., Mok, H.P., Peppa, D., Salgado, M., Martinez-Picado, J., Nijhuis, M., Wensing, A.M.J., Lee, H., Grant, P., Nastouli, E., Lambert, J., Pace, M., Salasc, F., Monit, C., Innes, A., Muir, L., Waters, L., Frater, J., Lever, A.M.L., Edwards, S.G., Gabriel, I.H., Olavarria, E. (2019) “HIV-1 remission following CCR5Δ32/Δ32 haematopoietic stem cell transplantation”, Nature, available from doi: 10.1038/s41586-019-1027-4.
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