Coverage of 2007 IAS
(International AIDS Society)

July 2007, Sydney, Australia

Apricitabine Study Shows Promise

July 26, 2007

Results from a small phase II study of the experimental NRTI apricitabine were presented at the 4th IAS Conference on HIV Pathogenesis, Treatment and Prevention in Sydney, Australia. Apricitabine is designed to work against HIV that harbors a genetic mutation- called M184V- that is associated with resistance to the two NRTIs, Epivir (lamivudine, 3TC) and Emtriva (emtricitibine, FTC). This drug-resistance mutation is common and effective alternatives for people who’s HIV has it could expand treatment options for a large number of people.

The study presented compared two different doses of apricitabine (600 and 800mg, both twice a day) to 150mg of Epivir, twice a day in people on failing regimens with Epivir. People were randomized either to add one of the two doses of apricitabine, or continue to take Epivir. Neither the investigators nor the people in the study knew to which group they had been assigned. After 21 days of functional monotherapy, people would switch to the best available combination of anti-HIV drugs, which could not contain either Epivir or Emtriva.

Data were presented from the 21-day, functional monotherapy phase of the study. People taking both doses of apricitabine experienced more significant declines in HIV levels, compared to those taking Epivir. People taking 600mg of apricitabine averaged a .9 log drop in HIV levels, while people taking 800mg had a drop of around .7 logs. Not surprisingly, people who continued to take Epivir had almost no decrease in HIV levels. There were no serious side effects seen in the study, and no new resistance was detected during this 21-day period. The longer term, second phase of the study is ongoing.

NRTIs are the oldest and most studied type of HIV drug. They are also considered to be the least potent. Historically they have played a supporting role in HIV drug therapy, due at least in part to the lack of alternatives. As more classes of HIV drugs become available, the role of this class of drugs is beginning to be scrutinized. More research is necessary before significant changes to the current structure of HAART are undertaken. For now, a new NRTI that will work against HIV that is resistant to the widely used drugs Epivir and Emtriva is welcome.