Doctors in Europe have announced a second person “cured” of HIV – the virus that causes AIDS. This is the second time doctors have placed a HIV patient into “sustained remission” with a stem cell transplant.
The news comes 10 years after Timothy Ray Brown, aka the “Berlin Patient” became the first HIV patient to be “functionally cured” of HIV, meaning the virus is totally undetectable in his bloodstream. Brown was able to stop taking antiviral medications after an intensive round of chemotherapy and radiation and two bone marrow transplants as part of his cancer treatment.
The 2nd person to be “cured” of HIV, who lives in London, was not identified in a medical paper published in the Nature Medicine journal. The 2nd person has not taken antiviral drugs since September 2017.
But researchers caution that those two cases do not mean everyone with HIV can be cured. Experts note it has taken 10 years just to “functionally cure” 2 people.
“It doesn’t change things for the average person with HIV right now,” said Dr. Bruce Walker, the director of the Ragon Institute that specializes in HIV/AIDS and infectious diseases. “It does change things in terms of the research agenda, because it further indicates that this is a potentially viable pathway forward to achieve a cure,” said Walker who was not involved in the Nature research.
Walker explained that some people have a mutation on specific white blood cells called T lymphocyte or T-cells in their immune system.
The T-cells are the body’s first line of defense against the HIV virus.
“You can sort of think of [these T] cells as the generals that are helping to orchestrate an effective defense,” Walker said. “If they’re not there, things tend to go haywire.”
The HIV virus attaches itself to a receptor on the T-cell called CCR5 which allows the virus to enter and infect the T-cells.
The HIV virus then uses the T-cell’s own DNA to make copies of itself, thereby destroying the T-cell from inside out. HIV can overwhelm the body’s immune system and kill off all the T-cells.
Walker says some people have a genetic mutation in the CCR5 receptor that prevents the virus from entering the T-cell. If the virus can’t enter the T-cell it can’t make copies of itself and the HIV virus eventually dies.
Walker explained that about 10% of people in some Northern European countries naturally carry the CCR5 mutation in their immune cells.
Like Timothy Brown, the 2nd person’s bone marrow transplant was part of his cancer treatment.
Doctors handpicked a transplant donor who had the CCR5 gene mutation. Unlike Brown, the 2nd person did not receive full body radiation as part of his cancer treatment.
Walker said that’s encouraging, but the risks from even this transplant regimen are too great to offer these kinds of stem cell transplants outside of cancer treatment.
“[T]here’s a very high bar for subjecting people to any additional risk,” Walker said. He added that the 2nd person’s transplant regimen “wasn’t without risk, but was much less [risky]” than Brown’s stem cell treatment regimen.
Walker pointed out that the CCR5-blocking power has been simulated with antiviral an medication since 2007.
U.S. drug companies Pfizer and GlaxoSmithKline have marketed a drug called Selzentry that prevents HIV from using the CCR5 receptor by binding to the receptor itself to prevent the virus from attaching to it.
But the drug has a downside. “Just like any other suppressive therapy for HIV, as soon as a person stops taking the drug, the virus comes roaring back,” said Dr. Keith Jerome, one of the leaders of HIV cure research at the Fred Hutchinson Cancer Research Center.
“The beauty of a transplantation or a gene therapy approach targeting CCR5 – that’s the kind of thing that looks like you can do it once, and then the person’s cured,” Jerome said. “They don’t need to worry about the virus any more, they don’t need to worry about their access to drugs or remembering to take it every day.”
Dr. Jerome said the best chance at eradicating the HIV virus is to perfect the stem cell transplant procedure or to edit the CCR5 receptor genes in humans.
One infamous case in China involving gene editing experimentations on unborn babies – who were later born with the CCR5 mutation – resulted in a worldwide backlash from scientists and ethicists who are concerned about doctors and scientists playing God.
Walker said he is skeptical of the Nature doctors announcing a cure for HIV.
“The virus may still be hiding out [in the body] someplace and it may come back 10 years from now,” Walker noted. “You can never be absolutely certain that a cure has been achieved.”
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