By Rachel Parratt
SYDNEY, AUSTRALIA -- July 27, 2007 -- New data from a study of the CCR5 antagonist maraviroc versus efavirenz showed noninferiority for HIV RNA levels <400 copies/mL, but not for <50 copies/mL, falling short of the stringent preplanned statistical analysis noninferiority margin of 10%.
Michael Saag, MD, Researcher, University of Alabama at Birmingham, Birmingham, Alabama, presented these findings in a late breaker session on July 25th at the 4th International AIDS Society (IAS) Conference on HIV Pathogenesis, Treatment and Prevention.
Overall, 721 HIV-positive patients (29% female) were randomized to Combivir® (zidovudine/lamivudine) with efavirenz or maraviroc.
Maraviroc was shown to be noninferior to efavirenz based on the <400 copies/mL endpoint (70.6% vs 73.1%), but not the <50 copies/mL endpoint (65.3% vs 69.3%). CD4 cell count increases were higher in the maraviroc group compared with efavirenz (+170 vs +144 cells/mm3).
The percentage of patients who discontinued treatment before 48 weeks was similar for both groups (maraviroc, 26.9% vs efavirenz, 25.2%).
The rate of discontinuation due to lack of efficacy was higher in the maraviroc group compared with the efavirenz group (11.9% vs 4.2%). Rate of discontinuation due to adverse events was lower in the maraviroc group compared with efavirenz (4.2% vs 13.6%).
Fewer patients experienced grade 3 or 4 adverse events in the maraviroc group than in the efavirenz group. The incidence of malignancies in general was lower in the maraviroc group.
"An interesting finding from this very recent data is the difference in results when stratified between Northern and Southern hemispheres," commented Dr. Saag. Northern hemisphere countries performed virtually equally, but there was a dramatic difference between Southern hemisphere countries; Argentina, South Africa, and Australia. These findings need to be explored further.
[Presentation title: A Multicenter, Randomized, Double-Blind, Comparative Trial of a Novel CCR5 Antagonist, Maraviroc Versus Efavirenz, Both in Combination With Combivir (Zidovudine [zidovudine]/Lamivudine [lamivudine]), for the Treatment of Antiretroviral Naïve Patients Infected With R5 HIV 1: Week 48 Results of The MERIT Study. Late Breaker WESS104]
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