A man from London has become the second person in the world
to be cured of HIV, doctors say.
Adam Castillejo is still free of the virus more than 30
months after stopping anti-retroviral therapy.
He was not cured by the HIV drugs, however, but by a
stem-cell treatment he received for a cancer he also had, the Lancet HIV
journal reports.
The donors of those stem cells have an uncommon gene that
gives them, and now Mr Castillejo, protection against HIV.
In 2011, Timothy Brown, the "Berlin Patient"
became the first person reported as cured of HIV, three and half years after
having similar treatment.
Stem-cell transplants appear to stop the virus being able
to replicate inside the body by replacing the patient's own immune cells with
donor ones that resist HIV infection.
Adam Castillejo - the now 40-year-old "London
Patient" who has decided to go public with his identity - has no
detectable active HIV infection in his blood, semen or tissues, his doctors
say.
It is now a year after they first announced he was clear of
the virus and he still remains free of HIV.
Lead researcher Prof Ravindra Kumar Gupta, from the
University of Cambridge, told BBC News: "This represents HIV cure with
almost certainty.
"We have now had two and a half years with
anti-retroviral-free remission.
"Our findings show that the success of stem-cell
transplantation as a cure for HIV, first reported nine years ago in the Berlin
Patient, can be replicated."
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But it will not be a treatment for the millions of people
around the world living with HIV.
The aggressive therapy was primarily used to treat the
patients' cancers, not their HIV.
And current HIV drugs remain very effective, meaning people
with the virus can live long and healthy lives.
Prof Gupta said: "It is important to note that this
curative treatment is high-risk and only used as a last resort for patients
with HIV who also have life-threatening haematological malignancies.
"Therefore, this is not a treatment that would be
offered widely to patients with HIV who are on successful anti-retroviral
treatment."
But it might offer hope of finding a cure, in the future,
using gene therapy.
How does it work?
CCR5 is the most commonly used receptor by HIV-1 - the
virus strain of HIV that dominates around the world - to enter cells.
But a very small number of people who are resistant to HIV
have two mutated copies of the CCR5 receptor.
This means the virus cannot penetrate cells in the body it
normally infects. Researchers say it may be possible to use gene therapy to
target the CCR5 receptor in people with HIV.
It is the same receptor the now jailed Chinese scientist He
Jiankui worked on when he created the world's first gene-edited babies.
Is it a permanent cure?
The tests suggest 99% of Mr Castillejo's immune cells have
been replaced by donor ones.
But he still has remnants of the virus in his body, as does
Mr Brown. And it is impossible to say with absolute certainty his HIV
will never come back.
Mr Castillejo told the New York Times: "This is a
unique position to be in, a unique and very humbling position.
"I want to be an ambassador of hope. I don't want
people to think, 'Oh, you've been chosen.'
"No, it just happened. I was in the right place,
probably at the right time, when it happened."
Prof Sharon Lewin, from the University of Melbourne,
Australia, said: "Given the large number of cells sampled here and the
absence of any intact virus, is the London Patient truly cured?
"The additional data provided in this follow-up case
report is certainly encouraging but unfortunately, in the end, only time will
tell." BBC
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