Two HIV patients are showing no signs of HIV after receiving bone marrow transplants to treat cancer, according to a case presented by David Cooper, director of the Kirby Institute at the University of New South Wales, while speaking at a press briefing at the 20th International AIDS Conference (AIDS 2014) in Melbourne, Australia.
Although the two patients, both Australian men, are seemingly HIV-free, they are both still on antiretroviral therapy (ART) as a precaution. As we've seen in two Boston patients who had similar HIV remissions after bone marrow transplants, the virus rebounded months after treatment was discontinued.
According to a report in the journal Nature, after hearing about the Boston patients last year, Cooper and his team started looking through the archives of St. Vincent's hospital in Sydney to see whether similar transplants had occurred in any of their HIV-positive patients. They found these two patients.
The first patient had received a bone marrow transplant to treat non-Hodgkin's lymphoma in 2011, while the second patient received treatment for leukemia in 2012. Interestingly, the first patient's replacement stem cells came from a donor who carried one copy of a gene that's thought to protect against HIV. Whether this was the CCR5 receptor mutation (as was the case for Timothy Brown, the first man functionally cured of HIV) was not reported.
According to the Nature report:
Because of the risk of relapse, Cooper's team will not claim that their patients are cured. But, he says, the results show that "there is something about bone-marrow transplantation in people with HIV that has an anti-HIV reservoir effect, such that the reservoirs go down to very low levels. And if we can understand what that is and how that happens, it will really accelerate the field of cure search."
Stem-cell transplant in itself cannot be used as a routine HIV treatment, because of the high mortality (10%) associated with the procedure. An important next step will be to find more such cases and compare them, says Cooper, to try to identify where the virus might be hiding. "These patients are very precious examples to help us understand how we might manipulate the immune system to drive the reservoir down to these extraordinary low levels."
Certainly, this is promising news, especially in light of the recent disappointing relapses in the Boston patients and "Mississippi Child," but it remains to be seen whether these two Australian patients are truly cured or need to remain on treatment.