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This subgroup analysis of the phase 3 DUET trials examined the impact of the background regimen on virologic response to etravirine in treatment-experienced patients.Patients received etravirine 200 mg or placebo, both twice daily with a background regimen of darunavir/ritonavir, investigator-selected nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), and optional enfuvirtide. Virologic response at week 48 (viral load50 HIV-1 RNA copies/mL) was analyzed by the number and activity of background agents.Baseline phenotypic sensitivity score (PSS), enfuvirtide use, darunavir fold change in 50% effective concentration (FC), and number of baseline darunavir resistance-associated mutations (RAMs) were significant predictors of response to etravirine (P.0001, P = .0018, P.0001, and P = .0120, respectively). The number of active NRTIs was not a significant predictor of response (P = .0626). The highest response rates in etravirine-treated patients were associated with PSS ≥2, de novo enfuvirtide use, darunavir FC ≤10, ≤1 darunavir RAM, and ≥2 active NRTIs. Virologic response was consistently higher in etravirine-treated patients than placebo-treated patients, regardless of the activity of the background regimen. Response rates according to baseline PSS were 46% to 79% in the etravirine group versus 6% to 75% in the placebo group.The results of this subanalysis demonstrate higher virologic response rates with increased activity of the background regimen in both treatment groups, with the highest responses achieved in patients using ≥2 active agents in addition to etravirine.

Study 903 is a phase 3 trial with a completed 144-week, double-blind phase comparing tenofovir DF (TDF) to stavudine (d4T) in combination with lamivudine (3TC) and efavirenz (EFV) and an ongoing additional 336-week open-label extension phase.Patients in Brazil, Argentina, and the Dominican Republic who completed the 144-week double-blind phase on TDF were eligible to roll over to the extension phase (weeks 144-480). Results from an interim week 288 analysis are presented.Eighty-six patients (62% male, 70% white) initially randomized to the TDF arm continued treatment with TDF. At the end of the 144-week, double-blind phase, 85 of the 86 had HIV-1 RNA400 copies/mL, of whom 84% maintained virologic suppression through week 288. CD4 counts continued to improve with a mean increase of 135 cells/mm(3) from entry into the open-label extension to week 288. No patient discontinued due to renal adverse events. Small changes in bone mineral density at the lumbar spine and hip were seen in the first 48 weeks but were nonprogressive through 288 weeks. Mean limb fat increased from 8.0 kg at week 96 to 8.8 kg at week 288.Through 288 weeks, once-daily TDF+3TC+EFV demonstrated sustained antiretroviral activity with continued immunologic recovery. TDF treatment was not associated with renal adverse events or limb fat loss in antiretroviral-naïve patients.

Study 903 is a phase 3 trial with a completed 144-week, double-blind phase comparing tenofovir DF (TDF) with stavudine (d4T), in combination with lamivudine (3TC) and efavirenz (EFV), and an ongoing 336-week open-label extension phase.Patients in 3 countries completing the d4T treatment phase were allowed to switch d4T to TDF and receive once-daily TDF+3TC+EFV in the extension phase.At the time of switch, 100% and 99% of patients (n = 85; 60% male, 64% White; mean age 37 years; mean CD4 = 650 cells/mm3) had HIV RNA400 and50 copies/mL. At 144 weeks after the switch, 89% (missing = failure) had HIV RNA400 copies/mL and 87% had HIV RNA50 copies/mL. Mean CD4 cell count increased 155 cells/mm3. No patient had virologic failure. Significant decreases from switch to week 144 in mean fasting total cholesterol (-22 mg/dL, p.0001) and triglycerides (-78 mg/dL, p.0001) were observed. Mean limb fat increased significantly from 4.5 kg to 5.8 kg, 144 weeks after switch (p.0001).In virologically suppressed patients, switching d4T to TDF as part of a once-daily regimen with 3TC and EFV resulted in maintenance of virologic suppression and continued CD4 cell increases through 144 weeks, with significant improvements in metabolic parameters.