TMC125-TiDP2-C238: An Exploratory Pharmacokinetics, Safety and Anti-HIV Activity Study of Etravirine (ETR) When Given With Boosted Atazanavir (ATV/Rtv) at Two Different Doses and 1 Nucleoside Reverse Transcriptase Inhibitor (NRTI) in Treatment Experienced HIV Patients

• PK interaction between ETR and ATV/rtv at 2 different doses; safety & tolerability of ETR in combination with ATV/rtv and 1 NRTI over 48 weeks. [ Time Frame: PK assessments- 9 timepoints during 24 hours at the PK days (Day -1 and Day 14), and safety-at all timepoints (all study visits). ] [ Designated as safety issue: No ]
  

• Assessing the impact of cytochrome P450 (CYP) 2C9 and 2C19 genotypes on ETR PK [ Time Frame: Week 48 ] [ Designated as safety issue: No ]
  
• Evaluating safety and tolerability of ETR in combination with ATV/r and 1 NRTI over 48 weeks [ Time Frame: Week 48 ] [ Designated as safety issue: No ]
  
• Evaluating the antiviral activity of ETR and ATV/r with 1 NRTI over 48 weeks [ Time Frame: Week 48 ] [ Designated as safety issue: No ]
  
• Evaluating the immunologic changes (as measured by CD4 cells) with ETR and ATV/r with 1 NRTI over 48 weeks [ Time Frame: Week 48 ] [ Designated as safety issue: No ]
  
• Evaluating changes in viral genotype and drug susceptibility [ Time Frame: Week 48 ] [ Designated as safety issue: No ]
  

This is a randomized (study drug assigned by chance), exploratory, open-label (all involved people know the identity of the intervention) trial to evaluate the pharmacokinetics (PK), safety, tolerability and anti-HIV (anti Human Immunodeficiency Virus) activity of etravirine (ETR ) when given with atazanavir/ritonavir (ATV/rtv) and 1 nucleoside reverse transcriptase inhibitor (NRTI) in 46 treatment experienced HIV-1 infected patients. The trial will consist of : 4 weeks of Screening Period, 2 weeks Pre-Treatment Phase, 48-week Treatment Period, and a Final Visit followed by a 4-week Follow-up Period (only for patients not continuing treatment with ETR in another trial or program). Safety evaluations (AE reporting, labs, vital signs, etc.) will be monitored at each study visit. A PK substudy (included in the protocol, with optional participation) with tenofovir (TDF) added to the antiretroviral regimen for 7 days will be conducted in patients with > 24 weeks of treatment with suppressed HIV-1 viral load. In Pre-Treatment Phase, all patients will receive ATV/rtv 300/100 mg once daily to be taken following a meal each morning + 2 NRTIs (dose as specified in the labels) for 14 days. In Treatment Phase, patients will receive ETR 200 mg twice daily in addition to ATV/rtv (300/100 mg or 400/100 mg) once daily with meals + 1 investigator-selected NRTI for 48 weeks. In substudy TDF 300 mg once daily will be added to the treatment regimen x 7 days.