Multicenter Pilot Study To Define The Marker As An Alternate For Tropism Assay

The study A4001060 has been discontinued on April 22, 2008. A review of the poor rate of
enrollment has projected difficulties in completing the study in a timely manner, despite the
best efforts by the sponsor and the sites. Given the difficulties encountered in this pilot
study and the need to conduct an even larger confirmatory study, the decision to discontinue
the study has therefore been made. It should be noted that safety concerns have not been seen
in this study and have not factored into this decision.

Inclusion Criteria:

- ≥ 16 years of age (or minimum adult age as determined by local regulatory authorities
or as dictated by local law) at the screening visit.

- Have an HIV RNA ≥ 1000 copies/mL, at screening.

- Subjects receiving another investigational antiretroviral compound through
participation in a phase 3 or 4 clinical study are eligible to participate in this
trial provided.

- That the 2 investigational agents are required to offer the subject a regimen with 2
or 3 active antiretroviral drugs (i.e. one or fewer approved treatment is available to
the subject due to prior resistance or intolerance),

- Neither protocol prohibits the use of the other antiretroviral agent, AND the dosing
of the two agents when used together is known AND a letter from the Pfizer clinical
pharmacologists for maraviroc identifies the dose of maraviroc to be used with other
investigational agents.

- Based on screening genotypic resistance testing results the subject must be able to
receive at least 3 active drugs other than maraviroc in the new OBT. This is defined
as:

- Having three drugs considered susceptible by genotype interpretation (if etravirine
will be used, fewer than 3 etravirine resistance mutations will be taken as etravirine
susceptibility); or,

- Having two drugs considered susceptible by genotype interpretation (if etravirine will
be used, fewer than 3 etravirine resistance mutations will be taken as etravirine
susceptibility) and be willing to include raltegravir in the OBT not having used
raltegravir in the past.

Exclusion Criteria:

- Potentially life threatening (Grade 4) laboratory abnormality or medical condition.

- Severe hepatic impairment (Child-Pugh classification B or C).

- End stage renal disease or other disease states requiring dialysis therapy.