Trial of Maraviroc (UK-427,857) in Combination With Optimized Background Therapy Versus Optimized Background Therapy Alone for the Treatment of HIV-1 Infected Subjects

Inclusion Criteria

• Men or women at least 16 years of age (or minimum age as determined by local regulatory authorities)
• HIV-1 RNA viral load of greater than or equal to 5,000 copies/mL
• Stable pre-study antiretroviral regimen, or on no antiretroviral agents, for at least 4 weeks
• Documented genotypic or phenotypic resistance to three of the four antiretroviral drug classes, OR, Antiretroviral-class experience greater than or equal to 6 months (sequential or cumulative) with at least three of the following: One nucleoside or nucleotide reverse transcriptase inhibitor, one non-nucleoside reverse transcriptase inhibitor, two protease inhibitors (excluding low-dose ritonavir) and/or enfuvirtide
• Be willing to remain on randomized treatment without any changes or additions to the OBT regimen, except for toxicity management or upon meeting criteria for treatment failure
• A negative urine pregnancy test at the baseline visit for Women of Child Bearing Potential (WOCBP)
• Effective barrier contraception for WOCBP and males

Exclusion Criteria

• Patients requiring treatment with more than 6 antiretroviral agents (excluding low-dose ritonavir)
• Prior treatment with maraviroc (UK-427, 857) or another experimental HIV entry inhibitor for more than 14 days
• Suspected or documented active, untreated HIV-1 related opportunistic infection (OI) or other condition requiring acute therapy
• Treatment for an active opportunistic infection, or unexplained temperature >38.5 degrees Celsius for 7 consecutive days
• Active alcohol or substance abuse sufficient, in the Investigator's judgement, to prevent adherence to study medication and/or follow up
• Lactating women, or planned pregnancy during the trial period
• Significant renal insufficiency
• Previous therapy with a potentially myelosuppressive, neurotoxic, hepatoxic and/or cytotoxic agent within 30 days prior to randomization or the expected need for such therapy during the study period
• Documented or suspected acute hepatitis or pancreatitis within 30 days prior to randomization
• Significantly elevated liver enzymes or cirrhosis
• Significant neutropenia, anemia or thrombocytopenia
• Malabsorption or an inability to tolerate oral medications
• Symptomatic postural hypotension or severe cardiovascular or cerebrovascular disease
• Certain medications
• Malignancy requiring parenteral chemotherapy that must be continued for the duration of the trial
• X4- or dual/mixed-tropic virus or repeated assay failure
• Any other clinical condition that, in the Investigator's judgement, would potentially compromise study compliance or the ability to evaluate safety/efficacy