Subgroup analysis of virological response rates with once- and twice-daily darunavir/ritonavir in treatment-experienced patients without darunavir resistance-associated mutations in the ODIN trial


Correspondence: Dr Michael Sension, Comprehensive Care Center, 1101 NW 1st St, Fort Lauderdale, FL 33311, USA. Tel: 954 467 3006; fax: 954 525 2030; e-mail:



ODIN (once-daily darunavir in treatment-experienced patients) was a 48-week, phase III, randomized, open-label trial comparing once-daily (qd) darunavir/ritonavir (DRV/r) 800/100 mg with twice-daily (bid) DRV/r 600/100 mg, both with an optimized background regimen [OBR; at least two nucleoside reverse transcriptase inhibitors (NRTIs)], in treatment-experienced, HIV-1-infected adults with no DRV resistance-associated mutations (RAMs) at screening. Week 48 analyses of virological response by subgroups are reported.


A total of 590 patients were randomized to receive qd (n = 294) or bid (n = 296) DRV/r. Virological response (HIV-1 RNA < 50 copies/mL) was assessed according to: screening HIV-1 RNA (≥ or < 50 000 copies/mL), CD4 cell count, prior protease inhibitor (PI) use, number of active NRTIs in the OBR, presence of mutations (primary PI mutations, PI RAMs or M184V/I), gender, age, race, HIV-1 clade and adherence.


Baseline characteristics were well balanced between arms and across subgroups. Response rates were comparable between qd and bid DRV/r treatments for all subgroups examined. Response rates were 78.4 and 76.8% in the qd and bid treatment arms, respectively, in patients with baseline HIV-1 RNA ≤ 50 000 copies/mL and 52.8% in both arms in those with > 50 000 copies/mL. Response rates for the qd and bid treatment arms by baseline CD4 cell count were also similar (69.6 vs. 65.2% for <200 cells/μL; 72.2 vs. 74.8% for 200− < 350 cells/μL; 77.0 vs. 74.3% for ≥ 350 cells/μL).


DRV/r administered either qd or bid provided effective treatment for antiretroviral treatment-experienced patients with no DRV RAMs, with comparable response rates across all subgroups studied. Low patient numbers in specific subgroups may limit interpretation of these specific subgroup results.