Vicriviroc, a CCR5 Inhibitor, Added to an Optimized Antiretroviral Therapy for Previously Treated HIV (VICTOR-E2) (Study P04285

Inclusion Criteria: * Adult subjects with documented R5/X4 mixed-tropic HIV infection * Prior therapy for greater than or equal to 3 months with greater than or equal to 3 classes of currently marketed antiretroviral agents (NRTIs, NNRTIs, PIs, or fusion inhibitors) at any time prior to screening * HIV RNA greater than or equal to 5000 copies/mL on a stable ART regimen of at least 3 months of duration * Greater than or equal to 1 genotypically documented resistance mutation to a reverse transcriptase (RT) inhibitor and greater than or equal to 1 primary resistance mutation to a PI * Acceptable hematologic, renal, and hepatic laboratory parameters. Exclusion Criteria: * No history of recurrent seizure or CNS condition predisposing to seizure * No active AIDS-defining opportunistic infection * Subjects who have previously used a CCR5 inhibitor for greater than 4 weeks and/or within 30 days of the screening visit * Use of any drugs that predispose to seizures.