Dose-finding Study of GSK2248761 in Antiretroviral Therapy-experienced Subjects With NNRTI-resistant HIV Infection

This 48 week, phase 2b study in 150 HIV-1 infected antiretroviral therapy experienced adult subjects consists of a dose-ranging evaluation of GSK2248761 at blinded doses of 100 mg and 200 mg once daily with a control arm of open-label etravirine (ETV) 200 mg twice daily. The background ART for all three arms will be darunavir/ritonavir (DRV/r) 600 mg/100 mg twice daily plus raltegravir (RAL) 400 mg twice daily. Antiviral activity, safety, PK, and development of viral resistance will be evaluated.

Study SGN113399 is a Phase 2b randomized, partially-blinded, multicenter, parallel-group, dose-ranging study to be conducted in HIV-1 infected ART-experienced adults with documented NNRTI resistance.

A minimum of 150 subjects will be randomized 1:1:1 to one of two GSK2248761 doses or a control regimen containing ETV (50 subjects per group); all subjects will also receive darunavir/ritonavir and raltegravir. The trial will be partially blinded, i.e. subjects receiving GSK2248761 and the investigators will be blinded to the dose they receive. Subjects will not be blinded to whether they receive GSK2248761 or ETV.

Randomization will be stratified by:

* HIV-1 VL at screening, \<50,000 copies/mL or \>/50,000 copies/mL, and
* Darunavir susceptibility (screening phenotype fold change \<7 or \>/7 to 20)

Background ART will be administered open-label.

The primary endpoint analysis will take place after all subjects have completed Week 16. An optimal dose of GSK2248761 will be determined by the Week 16 analysis; this dose selection will be confirmed using an analysis from all subjects following completion of Week 24. If there is a clear efficacy, safety or tolerability advantage driving dose selection for GSK2248761, then all subjects receiving the non-selected dose of GSK2248761 will be switched to the selected dose following dose confirmation, after all subjects have completed Week 24. If no differentiation of dose can be made based on objective measures of efficacy, safety or tolerability, then both doses will be continued through Week 48.

After Week 48, all subjects will be expected to obtain local access to all commercially available ART.

No regimen switches of either background ART (DRV/r and RAL) or test agent or control (GSK2248761 and ETV) are allowed during the 48 week period of the study.

Study Endpoints/Assessments Subjects will have assessments performed which will include baseline demographics, disease characteristics, pharmacogenetics (PGx) and safety (laboratory and clinical evaluations). On study safety, efficacy, virologic, immunologic, and PK evaluations will also be conducted.

The primary endpoint will be the proportion of subjects with HIV-1 RNA \<50copies/mL at Week 16. Dose selection will be based primarily on antiviral activity and tolerability in conjunction with immunologic, safety, virologic resistance and PK measures. Data from the Week 24 analysis will be used to confirm dose selection.

ViiV Healthcare is the new sponsor of this study, and GlaxoSmithKline is in the process of updating systems to reflect the change in sponsorship

Eligibility Criteria:
Inclusion Criteria:

* HIV-1 infected adults greater than or equal to 18 years of age. Females are eligible to enter and participate in the study if she is (1) non-childbearing potential, (2) child bearing potential with negative pregnancy test at screening and Day 1 and agrees to use protocol-specified methods of birth control while on study.
* HIV-1 infection with a screening plasma HIV-1 RNA greater than or equal to 400copies/mL
* Previously received or current treatment with antiretroviral therapy (HAART) for HIV-1 infection (patient may be off ART at time of screening)
* HIV-1 harboring NNRTI resistance by screening genotype (defined as the presence of at least 1 NNRTI resistance-associated mutations)

Exclusion Criteria:

* Any pre-existing physical or mental condition (including substance abuse disorder) which, in the opinion of the Investigator, may interfere with the subject's ability to comply with the dosing schedule and/or protocol evaluations or which may compromise the safety of the subject
* Any condition which, in the opinion of the Investigator, may interfere with the absorption, distribution, metabolism or excretion of the drug or render the subject unable to take oral medication
* Women who are currently breastfeeding
* Any evidence of an active Centers for Disease and Prevention Control (CDC) Category C disease \[CDC, 1993\], except cutaneous Kaposi's sarcoma not requiring systemic therapy
* History of ongoing or clinically relevant hepatitis within the previous 6 months, including chronic hepatitis B virus (HBV) infection (HBsAg positive). Asymptomatic individuals with chronic hepatitis C virus (HCV) infection will not be excluded, however Investigators must carefully assess if therapy specific for HCV infection is required; subjects who are anticipated to require such therapy during the randomized portion of the study must be excluded
* History of liver cirrhosis with or without hepatitis viral co-infection
* Ongoing or clinically relevant pancreatitis
* History of the following cardiac diseases: myocardial infarction, congestive heart failure, documented hypertrophic cardiomyopathy, sustained ventricular tachycardia
* Personal or known family history of prolonged QT syndrome
* History or presence of allergy or intolerance to the study drugs or their components, or a history of drug or other allergy that, in the opinion of the Principal Investigator, contraindicates their participation. In addition, if heparin is used during PK sampling, subjects with a history of sensitivity to heparin or heparin-induced thrombocytopenia should not be enrolled
* HIV-1 genotype results with any of the following will be excluded: (1)Any screening genotype with virus showing a Y181 mutation in combination with any other NNRTI resistance-associated mutations, (2) Any screening genotype with virus showing a Y181I or Y188L alone or in combination with any other NNRTI resistance-associated mutations
* HIV-1 phenotype results with any of the following will be excluded: (1) Any screening phenotype with virus showing etravirine fold change \>10, (2) Any screening phenotype with virus showing darunavir fold change \> 20, (3) Any screening phenotype with virus showing raltegravir fold change \>1.5
* Any acute laboratory abnormality at screening, which, in the opinion of the Investigator, would preclude the subject's participation in the study of an investigational compound. Any verified Grade 4 laboratory abnormality at screening would exclude a subject from study participation unless the Investigator can provide a compelling explanation for the laboratory result(s) and has the assent of the medical monitor
* Any of the following laboratory values at screening: (1) Creatinine clearance \<50 mL/min via Cockroft-Gault method, (2) Alanine aminotransferase (ALT) greater than or equal to 5 times ULN. Subjects with ALT \>2xULN but \<5xULN may participate in the study, if in the opinion of the Investigator and GSK medical monitor the lab abnormality will not interfere with the study procedures or compromise subject safety, (3) Alanine aminotransferase (ALT) greater than or equal to 3xULN and bilirubin greater than or equal to 1.5xULN (with \>35% direct bilirubin
* Any clinically significant finding on screening electrocardiograph (ECG), specifically (a single repeat is allowed to determine eligibility): (1) Heart rate \<45 and \>100bpm (males), \<50 and \>100bpm (females); Note: A heart rate from 100 to 110 BPM can be rechecked within 30 minutes to verify eligibility, (2) QRS duration \>120msec, (3) QTc interval \>450msec, (4) Non-sustained (greater than or equal to 3 consecutive beats) or sustained ventricular tachycardia, (5) Sinus pauses \>2.5 seconds, (6) 2nd degree (Type II) or higher AV (Atrioventricular) block, (7) Evidence of WPW (Wolff-Parkinson-White) syndrome (ventricular preexcitation), (8) Pathologic Q waves (defined as Q wave \>40msec OR depth \>0.4 mV, (9) Any other abnormality which in the opinion of the investigator would interfere with the safety of the subject
* Treatment with any of the following agents within 28 days prior to screening, or has an anticipated need for these agents during the study: (1) radiation therapy or cytotoxic chemotherapeutic agents, (2) immunomodulators (such as systemic corticosteroids, interleukins, or interferons); Note: Subjects using short-term (\<7 day) steroid tapers and inhaled corticosteroids are eligible for enrollment, (3) Any non-protocol-specified agent with documented activity against HIV-1 in vitro
* Treatment with an HIV-1 immunotherapeutic vaccine within 90 days prior to screening
* Receipt of an experimental drug and/or vaccine within 28 days or 5 half-lives, or twice the duration of the biological effect of the experimental drug or vaccine, whichever is longer, prior to screening
* Immunization within 28 days prior to first dose of IP