Google – AFP, Kerry Sheridan (AFP), 5 March 2014
 |
A new gene
therapy approach that engineers a person's T cells so that they
become
resistant to the human immunodeficiency virus has shown early signs
of success,
researchers said (AFP/File, Eric Piermont)
|
Washington
— A new gene therapy approach that engineers a person's T cells so that they
become resistant to the human immunodeficiency virus has shown early signs of
success, researchers said Wednesday.
Also called
gene editing, the process acts like molecular scissors to snip off an entry
portal for HIV so the virus cannot enter these key immune cells.
Once the
cells lack the CCR5 protein, the immune system behaves much the way it does in
a rare set of people -- about one percent of the population -- who are born
with a genetic mutation that prevents them from getting HIV.
 |
An
HIV-infected women with her
antiretroviral drugs in New Delhi on
July 23, 2012
(AFP/File, Andrew
Caballero-Reynolds)
|
Experts say
the development puts researchers a step closer on the path toward curing AIDS,
which has infected nearly 70 million people and killed some 35 million
worldwide.
"This
study shows that we can safely and effectively engineer an HIV patient's own T
cells to mimic a naturally occurring resistance to the virus," said senior
author Carl June of the University of Pennsylvania.
-
Repopulating the immune system -
Researchers
re-infused 12 patients with their own modified cells and saw them persist in
the body, essentially repopulating their immune systems.
Based on
the phase I trial results reported in the New England Journal of Medicine, the
technique was described as "generally safe."
One serious
adverse event was reported in a patient who was rushed to the emergency room
with fever, chills, joint pain and back pain within 24 hours of infusion.
Researchers
said the problem was likely a reaction to the study drug. All patients
completed the 36-week study and are being monitored for the next 10 years.
The
treatment also decreased, at least temporarily, the viral loads of some
patients taken off antiretroviral drug therapy, or ART.
The
patients were each given a single infusion of about 10 billion cells between
May 2009 and July 2012.
A dramatic
spike in modified T cells was seen in the patients' bodies a week after the
infusion.
Six people
were taken off ART for up to 12 weeks, beginning four weeks after infusion, and
the other six patients remained on treatment.
Four of the
patients who stopped ART saw their viral loads drop.
One patient's
viral load dropped so low that it became undetectable. Researchers later
discovered the person had inherited the CCR5 delta-32 gene mutation from one
parent, essentially giving the patient a head start on the treatment.
- A step
toward a cure? -
 |
Timothy R.
Brown on July 24, 2012 in
Washington, DC (AFP/File, Brendan
Smialowski)
|
June said
he hopes that modified T cells, an experimental approach that has also shown
promise against some forms of leukemia, could one day lead to a functional cure
for HIV/AIDS and eliminate the need for daily antiretroviral therapy.
So far,
only one man -- American Timothy Brown, often called the Berlin patient -- has
been cautiously considered cured of HIV after undergoing a bone marrow
transplant from a donor with a natural genetic mutation against HIV. He has
been off ART since 2008.
Researchers
have been trying for years to find a way to replicate those results for the
wider population, in a way that might be safer than a risky bone marrow
transplant, which carries a 30 percent risk of death.
While the
road to a cure is still long, experts praised the research for making
significant advances.
"If
gene therapy were found to be a way to cure HIV, I really do believe that
somebody is going to come up with a way that it could be delivered,"
Rowena Johnston, vice president and director of research at The Foundation for
AIDS Research, or amfAR, told AFP.
Anthony
Fauci, director of the National Institute of Allergy and Infectious Diseases,
which contributed funding to the research, described it as "clearly
promising."
"But
you have got to be careful that you don't at this point declare any victory
because we are still far from any widespread applicability," Fauci said.
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