Test predicts risk of HIV progression - Amplicor HIV-1 Monitor Test

FDA Consumer, Sept, 1996

A new test to predict the risk of HIV disease progression in infected patients has been licensed by FDA. The test is not labeled for use as a screening test for HIV or as a diagnostic test to confirm HIV infection.

The Amplicor HIV-1 Monitor Test measures blood levels of HIV-1--the strain of human immunodeficiency virus responsible for most HIV infections in the United States. It is the first licensed HIV-1 test using polymerase chain reaction (PCR) technology. PCR replicates millions of copies of genetic material (RNA) from HIV 1. The amplified RNA is tagged with color indicators so it can be measured. This technology enables more precise measurement than is possible with other approved technologies.

FDA licensed the test last June 3, less than seven months after receiving the manufacturer's application. Licensing was based on laboratory studies showing the test could measure HIV RNA in the blood, and on clinical data showing HIV blood levels correlated with disease progression

Laboratory studies showed the test was specific for HIV-1--that is, other unrelated viruses or organisms did not cause a false positive result (indicating the presence of HIV-1). Also, in an analysis of 495 samples known not to be infected with HIV-1, none was falsely positive.

In two small clinical studies, the test was used to measure viral levels in patients with advanced HIV disease who either had not received antiviral drugs or had received AZT (zidovudine, marketed as Retrovir) in combination with other antivirals for less than 16 weeks. Viral levels that were high before treatment or that increased fivefold after eight weeks of therapy correlated with disease progression to AIDS or AIDS-related infection or death.

In two additional clinical studies, the test was used to evaluate the effectiveness of antiviral therapy. Patients had been treated with AZT and were currently receiving the protease inhibitor saquinavir (marketed as Invirase) in combination with other drugs, such as AZT or DDC (also known as zalcitabine and marketed as Hivid). The test showed decreased levels of HIV-1 RNA in patients who received combination therapies.

The studies did not, however, show if changes in viral RNA levels are related to clinical responses to drug therapy. Last March, FDA's Blood Products Advisory Committee supported approval of the test for prognosis of HIV-infected patients, but recommended additional studies to determine how physicians could use the test to monitor the results of therapy. FDA required these studies, now under way, as a condition of licensing.

The manufacturer is Roche Diagnostic Systems Inc., Branchburg, N.J.