This study is a Phase II single arm, open-label, multicenter, study of 50 human immunodeficiency virus-1 (HIV) infected adult patients, all of whom will receive etravirine (ETR) 400mg and DRV/r 800/100mg each given orally once daily. This trial is designed to evaluate the efficacy of the aforementioned ARV regimen, as measured by the percentage of patients with HIV RNA <50 copies/mL at 48 weeks, in early treatment-experienced HIV-infected patients. In addition to general safety parameter measurements, this trial will also assess changes in metabolic, inflammatory, immune restoration, and bone markers. Screening will occur over a 6-week period. The primary endpoint will be assessed at Week 48, and the treatment period is 48 weeks. The end of study endpoint will be met by either completing the Week 48 visit, or by early termination from the study for any reason.

This study is a Phase II single arm, open-label, multicenter, (all people involved know the identity of the intervention) study of 50 HIV-1 infected adult patients, all of whom will receive ETR 400mg and darunavir (DRV)/r 800/100mg each given orally once daily. This trial is designed to evaluate the efficacy of the aforementioned ARV regimen, as measured by the percentage of patients with HIV ribonucleic acid (RNA) <50 copies/mL at 48 weeks, in early treatment-experienced HIV-infected patients. In addition to general safety parameter measurements, this trial will also assess changes in metabolic, inflammatory, immune restoration, and bone markers. Screening will occur over a 6-week period. The trial schedule includes a Baseline Visit (Day 1), Open-label Treatment Phase (Weeks 4, 8, 12, 16, 20, 24, 30, 36, 42, 48/ Early Withdrawal) and a Post-treatment Phase (4 Week Follow-Up) visit. In addition, all patients will have two pharmacokinetic (PK) samples drawn at Weeks 4 and 24, A single PK sample will be drawn at Weeks 12, 36, and 48 (or early withdrawal visit). There will also be a substudy conducting 24 hour intensive PK at week 4 for a subset of patients. For patients who consent, genotyping for CYP2C9 and CYP2C19 will be performed at Baseline. A Modified Medication Adherence Self-Report Inventory (M-MASRI) questionnaire will be collected, which is a patient-reported survey to assess adherence to medication taking. The primary endpoint will be assessed at Week 48, and the treatment period is 48 weeks. The end of study endpoint will be met by either completing the Week 48 visit, or by early termination from the study for any reason. ETR 400mg once daily for 48 weeks and DRV 800mg once daily for 48 weeks.

Inclusion Criteria:

• Male or female patients, aged 18 years or above
• Patients with documented HIV-1 infection
• On current HAART regimen for at least 12 weeks continuous duration at screening, and with an HIV-1 plasma viral load above 500 HIV-1 RNA copies/mL by site's currently utilized viral load assay (Note: For the purposes of this study, HAART is defined as treatment with a combination of 3 or more HIV antiretroviral medications from at least 2 different classes of medications (NRTIs, NNRTIs, PIs, integrase inhibitors, CCR5 antagonists, fusion inhibitors))
• No more than 2 previous virologic failures while on PI-containing HAART regimens where virologic failure is generally defined as either a lack of suppression of the subjects' viral load to lower limit of quantification (per standard assay historically used in care) after 24 weeks of treatment or, rebound of a previously suppressed viral load (undetectable per investigator's standard of care) to detectable limits and without demonstrated re-suppression on the same regimen
• Demonstrated phenotypic sensitivity to both etravirine and darunavir based on resistance testing at Screening (FC= 2.9 for etravirine and FC = 10.0 for darunavir using the PhenoSense GT)
• The absence of all of the following Resistance Associated Mutations (RAMS) at baseline: For Darunavir: V11I, V32I, L33F, I47V, I50V, I54L/M, T74P, L76V, I84V, L89V
• For Etravirine: L100I, E138A, I167V, V179D, V179F, Y181I, Y181V, G190S
• 7. CD4 count = 50 cells/mm3.

Exclusion Criteria:

• Primary HIV-1 infection
• Previously documented HIV-2 infection
• Use of disallowed concomitant therapy

Any condition (including but not limited to alcohol and drug use), which, in the opinion of the investigator, could compromise the patient's safety or adherence to the protocol

• Life expectancy less than 6 months according to the judgment of the investigator
• Patient has any currently active AIDS defining illness (Category C conditions according to the Center for Disease Control [CDC] Classification System for HIV infection 1993
• with the following exceptions, which must be discussed with the sponsor prior to enrollment: Stable cutaneous Kaposi's Sarcoma (i.e., no pulmonary or gastrointestinal involvement other than oral lesions) that is unlikely to require any form of systemic therapy during the trial period
• Wasting syndrome due to HIV infection if, in the investigator's opinion, it is not actively progressive and its treatment does not require hospitalization or compromise the patient's safety or compliance to adhere to trial-related procedures. If the patient is on maintenance therapy (which may include Growth Hormone, appetite stimulants and anabolic steroids) for previously diagnosed wasting syndrome, he/she may be eligible for the trial. Note: An AIDS defining illness not clinically stabilized for at least 30 days will be considered clinically active. Note: Primary and secondary prophylaxis for an AIDS defining illness is allowed in case the medication used is not part of the disallowed medications
• Any active clinically significant disease (e.g., pancreatitis, cardiac dysfunction) or findings during screening of medical history, laboratory or physical examination that, in the investigator's opinion, would compromise the patient's safety or the outcome of the trial.