PRO 140 for Human Immunodeficiency Virus Infection

Protocol PRO 140 2103 is a multicenter, randomized parallel group study, conducted in
approximately 40 male and female adult subjects (n=10/treatment group) infected with
CCR5-tropic HIV-1. Subjects will be randomized into one of four treatment groups. Blood
samples for drug concentrations, PD variables, and efficacy variables will be obtained over
a 59-day period following initiation of dosing. Safety will be monitored throughout the
course of the study.

Inclusion Criteria:

1. Males and females, age ≥18 years

2. Has not taken any antiretroviral therapy (ART) within 12 weeks of the early screening
visit

3. Screening plasma HIV-1 RNA ≥ 5,000 copies/mL

4. CD4+ lymphocyte cell count ≥500 cells/mm3 and no documented count less than or equal
to 250 cells/mm3

5. Exclusive CCR5-tropic virus as determined by as determined by the Enhanced
Sensitivity Trofile™ HIV Tropism Assay

6. Clinically normal resting 12-lead ECG at screening visit

7. Women of reproductive potential must have a negative serum pregnancy test at Late
Screening Visit. Within hours prior to receiving the first dose of study drug, women
of reproductive potential must have a negative urine pregnancy test. Male and female
subjects must agree not to participate in a conception process and agree to use one
barrier method of contraception plus one other highly reliable contraceptive method
from the early screening visit through three weeks after the last administered
subcutaneous dose of PRO 140.

Exclusion Criteria:

1. CXCR4-tropic virus, dual/mixed tropic (R5X4) virus as determined by the Enhanced
Sensitivity Trofile™ HIV Tropism Assay

2. Females who are pregnant, lactating, or breastfeeding, or who plan to become pregnant
during the study

3. Diagnosis of acute viral hepatitis (defined as any active infection with hepatitis A
or a new diagnosis of hepatitis B or C within 24 weeks of dosing)

4. Chronic hepatitis

5. Prior use of any entry, attachment, CCR5 coreceptor, or fusion inhibitor, including
PRO 140, experimental or approved

6. Any immunization or vaccination (including influenza vaccine) within 30 days prior to
administration of study drug.