First Genetic Test Hits Market to Show Which AIDS Drugs Will Fail in Each Patient

Food and Drug Administration (FDA) officials on Thursday announced their approval of the first gene-based test to tell quickly whether an HIV patient's virus is mutating, thereby making a particular drug therapy fail. The FDA described Visible Genetics Inc.'s TruGene, one of the most complex genetic test systems to clear the FDA, as an important tool in helping doctors select the most effective medication to fight each patient's HIV.

HIV naturally grows resistant to medications over time. Experts estimate that 60 percent of patients have a virus that is resistant to at least one drug. However, until now, the only way to discover which drugs a patient's HIV disease is resistant to was for the patient to undergo tests to monitor the amount of virus in the bloodstream. An increase in the viral load can mean that HIV is growing resistant to one or more drugs. To check a patient's blood for genetic mutations that affect one of the 15 AIDS drugs requires additional laboratory testing not routinely available.

With TruGene, a sample of blood is sent to one of 130 laboratories where Visible Genetics has trained personnel. Specially designed computer programs decode the HIV genes, identify all genetic mutations and match the mutations to a list of more than 70 mutations currently known and linked to resistance to specific AIDS drugs. The test takes three days to complete and will cost $300-$500 per patient.

"It's a major step forward in HIV treatment," said R. Scott Hitt, president of the American Academy of HIV Medicine. But "it is only one piece of the puzzle" in choosing the right medicine, he cautioned, urging patients to seek treatment from HIV specialists who can properly interpret the test results.

TruGene is 98 percent accurate, said FDA medical reviewer Dr. Andrew Dayton. More importantly, as scientists discover additional mutations -- a very rapidly changing field -- the new data can be added to the computer software so that the test remains accurate in everyday practice, he said.

FDA researchers tested the gene sequencer in an agency lab and approved the sale of TruGene late Wednesday after a year of review. This is record review time for such a complex new science, Visible Genetics president Richard Daly said. The test became available on Thursday.

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