Trial of Maraviroc (UK-427,857) in Combination With Optimized Background Therapy Versus Optimized Background Therapy Alone for the Treatment of Antiretroviral-Experienced NonCCR5-Tropic 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 two of the four antiretroviral drug classes, OR, Antiretroviral-class experience greater than or equal to 3 months (sequential or cumulative) with at least three of the following: One nucleoside or nucleotide reverse transcriptase inhibitor (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 judgment, 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, hepatotoxic 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 R5 virus phenotype only No option to use at least one non-nucleoside reverse transcriptase inhibitor or protease inhibitor, or enfuvirtide, based on resistance testing Any other clinical condition that, in the Investigator's judgment, would potentially compromise study compliance or the ability to evaluate safety/efficacy