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Once-daily elvitegravir matches raltegravir
Liz Highleyman, 2011-07-21 07:40:00
The experimental HIV integrase inhibitor elvitegravir works as well as raltegravir (Isentress) for treatment-experienced people with extensive drug resistance, and was well tolerated overall, according to data presented at the sixth International AIDS Society conference this week in Rome.
Integrase inhibitors prevent HIV from integrating its genetic material into the chromosomes of a host cell, a requirement for viral replication. The sole approved drug in this class, raltegravir, has enabled many highly treatment-experienced patients to bring their viral load under control, but resistance can develop if it is used without enough other active drugs.
Elvitegravir is a next-generation integrase inhibitor that can be taken once daily, whilst raltegravir is taken twice daily. But it must be used with a boosting agent, either ritonavir (Norvir) or the new pharmacoenhancer cobicistat. Elvitegravir and cobicistat are part of a single-tablet regimen known as the Quad pill (along with tenofovir/emtricitabine) that is being tested in treatment-naive people.
At the IAS conference, Jean-Michel Molina from Hôpital Saint Louis in Paris reported findings from Study 183-0145, the first randomized, head-to-head study of elvitegravir vs raltegravir for treatment-experienced people.
This international Phase 3 study included 702 participants. Most were men and the average age was 45 years. The mean CD4 cell count was approximately 260 cells/mm3, nearly half had CD4 counts less than 200 cells/mm3, and one-quarter had high viral load (> 100,000 copies/ml).
About two-thirds had virus resistant to two or more antiretroviral drug classes. However they were able to construct viable regimens that included a fully active ritonavir-boosted protease inhibitor (the ritonavir acts as a booster for elvitegravir as well) and an active third agent such as etravirine (Intelence), maraviroc (Celsentri) or a nucleoside/nucleotide reverse transcriptase inhibitor. Boosted darunavir (Prezista) and tenofovir (Viread) were the most commonly used other drugs.
Participants were randomly assigned to receive either 150mg elvitegravir once daily (dose adjusted if used with certain drugs) or 400mg raltegravir twice-daily. The researchers looked at proportions of patients achieving viral load suppression at 48 weeks; the study is continuing to follow patients to the 96 week point.
Elvitegravir and raltegravir were found to be equally effective, with 59% and 58%, respectively, achieving HIV RNA < 50 copies/mL. About 20% in both arms experienced virological failure. CD4 cell gains were also similar at around 140 cells/mm3 in both groups.
Both study drugs were well-tolerated overall and few people discontinued due to side effects (3% vs 4%, respectively). Adverse events and laboratory abnormalities were generally similar, though more elvitegravir recipients reported diarrhoea (12% vs 7%). About 20% of patients who experienced virological failure developed integrase resistance mutations.
The researchers concluded, on this basis, that elvitegravir was non-inferior to raltegravir when given with an active boosted protease inhibitor.
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