Health

IT IS a first for pharmacogenetics - and a potential lifeline for people with drug-resistant HIV. On 6 August, the US Food and Drug Adminstration (FDA) approved Pfizer's drug maraviroc, the first in a new class of HIV drugs designed to prevent the virus entering the immune system's CD4 cells.

Significantly, the drug will only be given to people who have had "pharmacogenetic" testing to show that their type of HIV enters CD4 cells via a particular molecule.

To enter the cells, HIV binds to both the CD4 receptor and one of two co-receptors, CCR5 and CXCR4. Maraviroc specifically blocks the CCR5 co-receptor, so the FDA has approved the drug for the 50 to 60 per cent of people with HIV who have forms of the virus that latch onto CCR5.

That will be determined using a test called Trofile, marketed by Monogram Biosciences of South San Francisco. This is the first time a drug has been approved on the condition that people have a genetic test on a virus.

Maraviroc is also intended only for people whose other HIV drugs no longer work, and will carry a warning of possible liver damage. Despite these safety concerns, the FDA has fast-tracked the drug because drug resistance is growing. "This is an important new product for many HIV-infected patients who have not responded to other treatments and have few options," says Steven Galson, director of the FDA's Center for Drug Evaluation and Research.

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.