October 27, 2008
Two posters looking at the new NNRTI Intelence (etravirine, TMC-125) were presented at the joint 2008 ICAAC/IDSA meeting in Washington, DC. One study found that the amount of time it took people to achieve full control of HIV while on Intelence did not affect how long their regimens continued to work. Another poster showed that fewer people taking Intelence compared to placebo experienced an AIDS-defining illness or death.
Intelence was approved in January 2008, based on data from the DUET 1 and 2 studies, which showed it to be superior to placebo in terms of reducing HIV levels and increasing CD4 counts. Each study group also took Prezista (darunavir) boosted with Norvir (ritonavir).
The first poster looked at whether there was a relationship between how quickly people in the DUET studies achieved HIV levels below 50, and how likely they were to maintain viral control after 48 weeks. A total of 599 people who took Intelence in DUET 1 and 2 were divided into 3 groups: 281 people who reached HIV levels below 50 within 12 weeks, 104 people who became undetectable in 12-24 weeks, and 214 people who did not become undetectable within 24 weeks.
In a conservative, intent-to-treat analysis (which counts people who leave the study or are otherwise lost to follow-up as treatment failures), 87% of people who reached undetectable within 12 weeks stayed so at 48 weeks, compared to 86% of people who reached undetectable in 12-24 weeks. Only 14% of people who hadn't achieved HIV levels below 50 by 24 weeks were undetectable at 48 weeks.
The relationship between the speed of viral load reductions and the durability of treatment has been raised recently due to studies which found that Sustiva (efavirenz) reduces HIV levels faster than Intelence, while Isentress (raltegravir) reduces them faster than Sustiva. This study suggests that the speed at which someone responds to treatment with Intelence does not predict if they are likely to maintain good viral control after 48 weeks.
A second study looked at the rates of AIDS-defining illnesses and death in people taking Intelence compared to placebo in the DUET studies. This analysis is crucial, as approval of Intelence was based primarily on surrogate markers, like HIV levels and CD4 counts, rather than its impact on HIV disease.
Slightly over 1,200 people from DUET 1 and 2 were studied. There were 59 AIDS-defining illnesses or deaths (9.8%) for those on placebo compared to 35 (5.8%) for people taking Intellence. The difference was larger when people in the placebo group taking Sustiva for the first time were excluded.
These two studies, combined with earlier results, show that Intelence is an effective treatment option for people with experience taking HIV drugs. Intelence is the first second-generation NNRTI, and it's important because unlike other NNRTIs it is able to overcome resistance to other NNRTIs like Sustiva and Viramune (nevirapine). There is very limited data on using Intelence with protease inhibitors other than Prezista.