Two Australian men who had been receiving HIV treatment have both had their viral loads brought down to undetectable levels following bone marrow transplants. The announcement came from David Cooper from the University of New South Wales during a press briefing ahead of next week’s 20th International AIDS Conference in Melbourne.
The two men, ages 47 and 53, respectively received bone marrow transplants three and four years ago to treat lymphoma and leukemia. Though the HIV virus is no longer detectable in either of them, they are still undergoing antiretroviral therapy (ART) as a precaution, and Cooper refuses to say that the men have been “cured” due to the possibility of relapse, as witnessed in other patients whose viral loads had dropped to undetected levels only to reappear later.
HIV can hide within the body in what is called the latent reservoir. Here, the virus becomes inactive and therefore cannot be targeted by ART. Eventually, the virus can become reactivated and begin to reproduce. It was announced last fall that the reservoir is up to 60 times larger than previously believed, which makes the task of finding the hidden virus much more difficult.
At last year’s conference of the International AIDS Society, Timothy Henrich from Boston’s Brigham and Women’s Hospital announced that he had helped treat two patients whose HIV also became undetectable following bone marrow transplants. One of the patients received bone marrow from an individual who had one copy of a rare variant of the CCR5 gene which prevents HIV from infecting target cells. Both men quit taking ART, but the virus returned several months later. It was this announcement that inspired Cooper to investigate his records and find HIV patients who had received bone marrow transplants.
In 2010, a baby was born in Mississippi to a woman who did not know she was infected and had not taken ART throughout the pregnancy, which would have drastically reduced the chance for transmission. Starting one day after birth, the baby was subjected to an aggressive medication regime in order to reduce the virus. After 18 months, the HIV was no longer detectable and the treatment stopped for the next two years. Unfortunately, it was announced last week that a routine blood test showed that the virus had returned, and the child is again receiving treatment.
Only one person has been able to stay functionally “cured” of HIV following a bone marrow transplant. American Timothy Ray Brown, better known as The Berlin Patient, received a bone marrow transplant in 2008 to treat his acute myeloid leukemia. His donor had both copies of the HIV-resistant CCR5 variant and the HIV became undetectable in his system after the procedure. Even without continuing ART, he has remained free of the virus.
Bone marrow transplants can be dangerous and have a 10% mortality rate, so it is not something that could be used as a quick fix for the 35 million people around the globe with HIV. However, by analyzing the patients who have had the virus made undetectable, scientists can learn more about the mechanisms that fight HIV and find a safer way to replicate that process.
