In early 2011, a single-arm study of the NRTI-sparing regimen of darunavir/ritonavir (800/100 mg QD) plus raltegravir (400 mg BID) reported worrisome rates of virologic failure, particularly among subjects with baseline HIV RNA levels of >100,000 copies/mL.(1) At ICAAC, researchers involved in a second study to evaluate this combination presented their 24-week results.
In the small RADAR trial (n=80), treatment-naive subjects were randomized to receive darunavir/ritonavir (QD) with either raltegravir (BID) or tenofovir/emtricitabine. The median baseline HIV RNA was 4.72 log10 copies. At 24 weeks, rates of HIV RNA suppression to <50 copies/mL were 86% and 87%, respectively, with 2 subjects in the NRTI-sparing arm and none in the comparator arm experiencing virologic failure. Increases in CD4 counts were 149 cells/µL and 125 cells/µL, respectively.(2) The study was not powered to make statistical comparisons between treatment arms.
| Clinical Bottom Line|
In the RADAR study, treatment with darunavir/ritonavir + raltegravir resulted in rates of virologic suppression at 24 weeks that were high, and they were equivalent to those achieved with standard therapy. It is not clear, however, why the results of this study are so different from those reported in the ACTG trial. Accordingly, pending further study, this and most other NRTI-sparing combinations should be used with caution in individual patients.
1. Taiwo B, Zheng S, Gallien S, et al; ACTG A5262 Team. Results from a single-arm study of DRV/r + RAL in treatment-naive HIV-1-infected patients (ACTG A5262). In: Program and abstracts of the 18th Conference on Retroviruses and Opportunistic Infections; February 27-March 2, 2011; Boston. Abstract 551.
2. Bedimo R, Drechsler H, Turner D, et al. RADAR study: raltegravir combined with boosted darunavir has similar safety and antiviral efficacy as tenofovir/emtricitabine combined with boosted ritonavir in antiretroviral-naive patients. In: Program and abstracts of the 6th International AIDS Society Conference on HIV Pathogenesis, Treatment, and Prevention (IAS 2011); July 17-20, 2011; Rome. Abstract MOPE214.