Tuesday, July 3, 2012

Stem-cell transplant rids man of HIV

Stem-cell transplant rids man of HIV

An American man remains HIV-free more than three years after receiving a stem-cell transplant, suggesting the first cure of the virus that causes AIDS, German doctors said.

While the risky technique used on Timothy Ray Brown, 44, would not work for most of the 33 million people with HIV worldwide, scientists say the research shows important progress toward a universal cure.

"Our results strongly suggest that cure of HIV has been achieved in this patient," said the study in the peer-reviewed journal Blood, a publication of the American Society of Hematology.

The process began in 2006 when Mr Brown, who had been HIV positive for more than a decade, sought treatment for acute myeloid leukemia, a lethal blood cancer.

After a first round of chemotherapy failed, his German doctor Gero Hutter decided to perform a bone-marrow transplant using a donor with a rare genetic mutation that is naturally resistant to HIV.

About one in 100 Caucasian people, or 1 per cent of the population, have the mutation known as Delta 32, inherited from both parents which prevents the protein CCR5 from appearing on the cell surface.

Because HIV enters the cell through CCR5 molecules, the virus cannot penetrate when they are absent.

After rejecting dozens of potential donors, Dr Hutter found a match and performed the bone-marrow transplant using stem cells from the HIV-resistant donor in February 2007.

Dr Hutter's first study, published in the New England Journal of Medicine in 2009, showed no sign that HIV had re-emerged even though the patient had ceased anti-retroviral therapy to suppress HIV.

The latest findings show Mr Brown continues to show no trace of either the AIDS-causing virus or leukaemia.

But AIDS experts have sounded a note of caution.

Mr Brown's ordeal left him temporarily unable to walk or talk and statistics show around 30 per cent of patients do not survive bone-marrow transplants.

"We need a lot more research to try to replicate this without putting a patient's life in danger," said Karen Tashima, director of the HIV clinical trials program at the Miriam Hospital in Rhode Island.

"Since we have good anti-retroviral therapy that can control the virus, it would be unethical to give somebody such an extreme treatment."

Lead study author Kristina Allers acknowledged the process will not work for most people but says it is still significant.

"As the study tells us that [an] HIV cure is in-principle possible, it gives new hope for scientists in HIV cure research," she said.

"The next challenge is to translate our findings into a strategy that can be applied without being life-threatening."

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