Who Should Consider HIV Tropism Testing for Maraviroc Response?

Experts, such as the U.S. Food and Drug Administration and the Department of Health and Human Services, agree that all people planning to start maraviroc (Selzentry®) therapy should have human immunodeficiency virus may also be considered for people taking maraviroc who are not responding as hoped.

Before starting therapy

Maraviroc drug information (approved by the US Food and Drug Administration) says that only adults with CCR5-tropic HIV should take maraviroc. Maraviroc only works in people with CCR5-tropic HIV. It does not work on those with CXCR4-tropic HIV, or HIV that uses both receptors.

The way to find out which receptor your kind of HIV infection uses is with HIV tropism testing. Everyone considering maraviroc therapy needs to have HIV tropism testing before taking the drug. In rare cases, therapy may start before these test results are available. In these rare cases, testing should be done as soon as possible.

When therapy doesn’t work

Some experts believe that HIV tropism testing should be repeated if maraviroc doesn’t work as expected. There are many reasons maraviroc may not work, including a dose that is too low, not taking the drug regularly enough, or being resistant to the drug for reasons other than HIV tropism.

Another important reason maraviroc may stop working is that HIV viral tropism can change over time. Someone who has CCR5-tropic virus at the beginning of therapy can later have CXCR4-tropic virus.

A Department of Health and Human Services Panel on Antiretroviral Guidelines for Adults and Adolescents recommends:

“Coreceptor tropism assay should be performed whenever the use of a CCR5 inhibitor is being considered.”

“Coreceptor tropism testing might also be considered for patients who exhibit virologic failure on a CCR5 inhibitor.”

Copyright © 2011 Aspirus Genetics