Effect of Vicriviroc on HIV Ribonucleic Acid (RNA) Levels in Cerebrospinal Fluid (Study P05241)

• A subject must be at least 18 years of age at the time of study entry, of either sex, and of any race.
• A subject must be infected with HIV-1 virus, as documented by a positive assay for HIV-1 RNA in plasma, prior to Screening.
• A subject's HIV isolate must be solely CCR5-tropic at Screening (ie, a subject must not have detectable CXCR4-tropic or dual/mixed CCR5/CXCR4-tropic HIV isolates).
• Subjects must be failing their current antiretroviral regimen with plasma HIV RNA >=1000 copies/mL at the time of screening. (Note: The failing background regimen must contain a ritonavir-boosted PI, and may not include an NNRTI.)
• A subject must be willing to undergo study procedures including lumbar punctures, and to adhere to the chosen antiretroviral regimen.
• A subject must have a pretreatment CSF HIV RNA of >=200 copies/mL.

Exclusion Criteria:

• A subject must not be taking medication for seizure control or have any condition that, in the judgment of the investigator, is likely to increase the risk of seizures.
• A subject must not have a prior history of malignancy (with the exception of surgically resected basal cell carcinoma with clear margins or Kaposi's sarcoma without visceral or mucosal involvement that resolved without systemic anticancer treatment).
• A subject must not have a contraindication to lumbar puncture (eg, bleeding diathesis or use of anticoagulants).