Gene therapy offers hope of cure for HIV
Doctors rid man of the virus with bone marrow transplant
breakthrough
Doctors have succeeded in ridding a man of the HIV virus by
giving him a bone marrow transplant in what they claim is the
closest treatment yet to a cure for the disease.
The remarkable case gives new impetus to the development of gene
therapy for HIV which could ultimately replace the need for
expensive and toxic antiretroviral drugs. Instead of taking drugs
for life, HIV sufferers might instead have a one-off treatment that
would leave them virus-free.
The 42-year-old American had been infected with HIV for a
decade. He was treated with antiretroviral drugs in Berlin, where
he lives, for four years to hold the disease in check, but then
developed leukaemia. Since being given a bone marrow transplant two
years ago, he has not taken antiretroviral drugs to control HIV and
has had no resurgence of either disease. He is believed to be the
longest HIV-free survivor who was previously treated with
antiretroviral drugs. Full details of the case are published for
the first time today in The New England Journal of Medicine. An
editorial in the journal says it "places further emphasis on gene
therapies" for HIV, adding: "The case paves the way for innovative
approaches that provide long-lasting viral control with limited
toxicities for persons with HIV infection."
The man's treatment began with a search by doctors at Berlin's
Charité Hospital for a bone marrow donor with a genetic resistance
to HIV. One of the strangest features of the disease is the way
some people who have been exposed to the virus on many occasions
remain uninfected. Twenty years ago, it was noticed that certain
prostitutes in Nairobi remained uninfected despite exposure to the
virus through thousands of sexual contacts.
It has since emerged that some people carry a mutation of a gene
(CCR5) that confers protection against HIV. In Western populations
an estimated one to three per cent have the mutation.
Dr Gero Hutter, a haematologist at the Berlin Charité Hospital,
and colleagues tested 61 potential donors before they found one
with the CCR5 genetic mutation, who agreed to the operation.
The American recipient of the transplant, who runs a holiday
rentals business in the German capital, has undergone regular
checks in the two years since the treatment. The doctors have
tested his bone marrow, blood and tissues and found no sign of HIV.
"For as long as the viral load remains undetectable, this patient
will not require antiretroviral therapy," they say in the
journal.
Speaking to The Independent yesterday, Dr Hutter said there had
been several previous reports of patients being virus-free
following treatment but none to compare with the latest case. "The
difference is that in our patient we had a plan. It was not an
accident," he added. "It is the longest time someone who has had
antiretroviral therapy and stopped has lasted without the virus
rebounding. Normally it rebounds within weeks. It is the closest we
have come to a cure."
Dr Hutter said a bone marrow transplant would be too risky as a
routine treatment for HIV and too difficult to find donors with the
right genetic make-up. But a modification of the approach using
gene therapy to render a patient HIV-resistant could work, he
said.
Even a costly treatment could be worthwhile. The price of
treatment with antiretrovirals in Europe is €70,000 to €80,000
(£63,000 to £72,000) a year compared with a one-off cost of €20,000
to €30,000 for a bone marrow transplant.
Dr Hutter said: "When I started in medicine, HIV was completely
untreatable. Now the situation has changed completely. Perhaps our
case is a glimpse of hope for the future."
Professor Jay Levy, an Aids specialist at the University of
California, and author of the US journal's editorial, said claims
that the patient had been cured of HIV would be premature because
of the virus's capacity to hide in other parts of the body
including the brain, gut, liver and lymphatic system, from which it
could always re-emerge.
"Nevertheless, the results… provide further encouragement for
those examining approaches to treatment that reduce CCR5 expression
in persons with HIV infection," he writes.In 2007, an estimated two
million people died from Aids and 2.7 million were newly infected
with HIV.
25 years of research: The HIV virus
When the discovery of HIV was announced in 1984, US politicians
predicted that a cure for Aids would be found within five years,
but it is still a distant prospect.
Over the past 10 years, a cocktail of aggressive antiretroviral
drugs has been developed to help keep the effects of the disease at
bay. Eliminating it has proved far more difficult because of the
virus's unique nature.
HIV integrates itself into an infected person's DNA and attacks
the cells the immune system sends to attack it. Once infected,
these T-cells take the virus deeper into the body. Gene therapy is
a new approach that harnesses the natural resistance to HIV shared
by 3 per cent of people.
Experts hope that by tweaking a sufferer's DNA, they can achieve
"long-lasting viral control".
