7th International AIDS Society Conference, Kuala Lumpur, June 2013:
Researchers have reported that two HIV-positive men who received stem cell transplants to treat their cancer have no detectable HIV despite interrupting HIV treatment for at least seven weeks. These data, presented Wednesday, July 3 at the 7th IAS Conference on HIV Pathogenesis, Treatment and Prevention in Kuala Lumpur, don’t mean — necessarily — that these men have been cured of HIV, but they are very promising and this result has not been seen before.
As reported earlier and published in March in the Journal of Infectious Diseases, researchers at Brigham and Women’s Hospital in Boston found two HIV-positive men who had undergone stem cell transplants, with the new cells coming from a donor. In contrast to the way that many stem cell transplants were handled in the past, these two men had something called a reduced intensity conditioning regimen before the transplant, meaning that the therapy to deplete their own immune systems to make space for the donor cells was more gentle and did not require the men to go off HIV treatment during the procedure.
The researchers previously reported that no traces of HIV could be found in blood in the men after approximately three years post-transplant. At the IAS conference on Wednesday, the researchers reported new data. They have now conducted three additional experiments. First, the researchers took a much deeper look for virus in peripheral blood mononuclear cells (PBMCs) of both patients. None could be found. Second, the researchers took a sample of gut tissue from one of the men and again no virus could be found.
Finally, in what will be the litmus test for any cure-oriented strategy, the researchers had both men stop taking their antiretroviral (ARV) regimens. At this point, one of the men has been off treatment for 7 weeks and the other for 14 weeks. In both cases virus has not rebounded. In fact, it is still undetectable.
While this result is highly unusual and promising, it should be stressed that we cannot yet call these men “cured,” despite what some reporters and bloggers will inevitably report. Nevertheless, these results do suggest that both men could manage to remain off HIV treatment for some time to come.