Hepatitis B drug triggers HIV resistance

Authors of the study have notified Bristol-Myers Squibb, which makes and sells entecavir under the brand name Baraclude. They have also informed the FDA so that prescribing physicians can be notified and so that drug labeling can be changed.

“Our results show that entecavir is no different from any other that has been shown to be active against HIV – it breeds resistance rapidly, despite its ability to reduce the amount of HIV in the body,” said senior study author Chloe Thio.

Researchers say the findings have serious implications for more than 4 million people worldwide believed to be infected with both viral illnesses but who need to treat their hepatitis B and are not yet on anti-HIV drugs.

In the study, researchers found that within six months of entecavir therapy, a so-called M184V mutation of HIV develops. The researchers said viruses with this mutation are known to be resistant to lamivudine, a medication that prevents HIV replication. Because lamivudine is in the same category of HIV therapies as another widely used drug, emtricitabine, its effectiveness is also compromised by entecavir.

Study results showed that entecavir cut the number of newly infected cells in half. However, at increasing concentrations, the drug had no greater impact on suppressing HIV replication.

Similar testing with entecavir, immune cells and the M184V form of HIV showed that the drug did not stop the virus from infecting the cells. This provided evidence scientists say that the drug specifically fostered development of this mutation in HIV.

When researchers tested the blood of one of the co-infected patients for the M184V mutation, they found none in samples taken at the start of entecavir therapy. But they did find it in 61% of viral samples tested after four months of therapy, and 96% at six months.