For two years, a 42-year-old man has tested HIV negative after a stem cell transplant carrying a gene mutation that confers natural resistance to the HIV virus.
On Wednesday the New England Journal of Medicine published a report on the patient of Dr. Gero Hutter of Charite Universitatsmedizin Berlin in Germany.
In November the story broke about what appears to be a cured patient. The journal report in this month’s issue is the first official publication of the case.
As the summary states this is an exciting time in HIV research.
Infection with the human immunodeficiency virus type 1 (HIV-1) requires the presence of a CD4 receptor and a chemokine receptor, principally chemokine receptor 5 (CCR5). Homozygosity for a 32-bp deletion in the CCR5 allele provides resistance against HIV-1 acquisition. We transplanted stem cells from a donor who was homozygous for CCR5 delta32 in a patient with acute myeloid leukemia and HIV-1 infection. The patient remained without viral rebound 20 months after transplantation and discontinuation of antiretroviral therapy. This outcome demonstrates the critical role CCR5 plays in maintaining HIV-1 infection
Two years ago the American patient living in Germany underwent a stem cell transplant to treat leukemia. The treatment was not used to treat the HIV itself. However the team of doctor chose a donor who had the CCR5 delta32 mutation. CCR5 is a receptor that is normally found on the surface of T cells. Those are the immune system cells attacked by the HIV virus. Only 1 percent to 3 percent of white populations of European descent carry the delta32 mutation.
When a person is infected with HIV the virus uses the CCR5 in addition with CD4 receptors to latch on and in time destroy immune system cells. When a person has the delta32 mutation the virus can’t get that foothold because of the lack of CCR5 cells. People with the natural therefore have a natural protection from the most common strains of HIV.
It appears that people with one copy of CCR5 delta32 take longer to get sick or develop AIDS if they are infected with HIV. People with two copies of the mutation may not be able to get infected at all.
The patient in this case had a donor with two copies of CCR5 delta32.
CNN Health reports:
While promising, the treatment is unlikely to help the vast majority of people infected with HIV, said Dr. Jay Levy, a professor at the University of California San Francisco, who wrote an editorial accompanying the study. A stem cell transplant is too extreme and too dangerous to be used as a routine treatment, he said.
“About a third of the people die [during such transplants], so it’s just too much of a risk,” Levy said.
While the patient appears to be clear of the virus doctors will not say that he is cured. Still the patient seems to be free of leukemia and HIV is absent from his body.
One year ago the patient had a relapse of leukemia and a second transplant from the same donor. He had some medical complications with his liver and kidney. Those complications are common with transplants and in this case were temporary.
This new treatment in time could be used to treat the HIV virus but it is still at least five years away for standard use. It is still a possible light at the end of a long tunnel for patients of the virus.
“For HIV patients, this report is an important flicker of hope that antiretroviral therapy like HAART [highly active antiretroviral therapy] is not the endpoint of medical research,” Hutter said.