Spain, at the forefront of HIV research
Spanish researchers at Gregorio Marañón Hospital in Madrid and IrsiCaixa-Institut de Recerca de la Sida in Barcelona might have found a way to remove HIV from the body. They have published a study that reveals stem cell transplant factors might contribute to HIV reservoir eradication.
The multi-centre study, published in Annals of Internal Medicine, included six HIV-infected patients with antiretroviral treatment and haematological conditions who had received stem cell transplant. 5 of them showed undetectable HIV. Moreover, in one case the HIV antibody level was zero.
This finding might lead to the design of new, more effective, treatments. Actually, one of the reasons anti-HIV drugs do not cure the infection is that they are ineffective in removing the latent HIV reservoir, made of infected cells where the virus can hide out from the immune system for years.
The authors of the study explain that the origins of the stem cells used in the transplants – cord blood in one case and marrow bone in the remaining cases –, as well as the time to achieve full replacement of recipient cells with donor cells – up to 18 months in one patient – could have contributed to the potential removal of the virus.
After the transplant, all the participants in the study continued to get antiretroviral treatment and achieved remission of their haematological conditions without immunosuppression. Five of them had undetectable reservoir in blood and all analysed tissues. This is relevant because these parameters are always detectable in HIV-infected people, despite effective antiretroviral treatments.
Timothy Brown and CCR5 Delta 32
The study was built upon the case of an HIV-positive patient, Timothy Brown, who received a stem cell transplant to treat leukaemia. The donor had a mutation named CCR5 Delta 32 that made his blood cells nearly immune to HIV. Brown stopped taking HIV medication and today, 11 years after stem cell transplantation, the virus is no longer found in his blood. He is thought to be the only individual to have been cured of HIV.
The study included six participants who had survived transplantation for more than two years. None of them had the CCR5 Delta 32 mutation. The authors of the study believe that, in addition to the mutation, there were other mechanisms associated with the transplant that were involved in the eradication of the virus from Timothy Brown’s body.
Now, the next step will consist in performing a clinical trial that combines new immunotherapies with medically supervised removal of antiretroviral drugs in some of the patients, in order to find out whether the virus has been eradicated from their bodies.