Attachment Inhibitor Comparison in Heavily Treatment Experienced Patients

Inclusion Criteria:

- Men and non-pregnant women with chronic HIV-1 infection

- Antiretroviral-experienced with documented historical or baseline resistance,
intolerability, and/or contraindications to antiretrovirals in at least three classes

- Failing current antiretroviral regimen with a confirmed plasma HIV-1 RNA ≥ 400 c/mL
(first value from Investigator, second from Screening labs)

- Must have ≤ 2 classes with at least 1 but no more than 2 fully-active antiretrovirals
remaining which can be effectively combined to form a viable new regimen, based on
current and/or documented historical resistance testing and tolerability and safety

- Able to receive ≥ 1 fully active approved antiretroviral as part of the OBT from Day 9
onwards in the Randomized Cohort

- Subjects without any remaining fully active approved antiretroviral may be enrolled in
the Non-Randomized Cohort

Exclusion Criteria:

- Chronic untreated Hepatitis B virus (HBV) (however, patients with chronic treated HBV
are eligible)

- HIV-2 infection

- Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) > 7 x ULN

- Alkaline Phosphatase > 5 x ULN

- Bilirubin ≥ 1.5 x Upper limit of normal (ULN) (unless subject is currently on
atazanavir and has predominantly unconjugated hyperbilirubinemia)