Dose Escalation Study of Cyclophosphamide in HIV-Infected Subjects on HAART Receiving SB-728-T

The objectives of the study are to augment HIV-specific T-cells and to reverse or decrease
the progressive destruction of CD4+ T-cells that leads to clinical AIDS. Levels of
engraftment vary from negligible to about 10% of the CD4+ T-cells in the vascular
compartment. Preliminary analyses of HAART TI suggest that an anti-HIV effect may correlate
with the level of SB-728-T engraftment. Concurrently, non-myeloablative lymphodepletion with
cyclophosphamide has been demonstrated to enhance engraftment of adoptively transferred
T-cells through a variety of mechanisms. The study is being undertaken to increase SB-728-T
engraftment through the administration of low non-myeloablative doses of cyclophosphamide.

Inclusion Criteria:

- Male or female, 18 years of age or older with documented HIV diagnosis within 10 years
of screening.

- Must be willing to comply with study-mandated evaluations; including discontinuation
of current antiretroviral therapy during the treatment interruption.

- Must have received at least 6 months of continuous HAART therapy and have had
undetectable VLs for the preceding 3 months.

- On stable antiretroviral medication (no changes to treatment within 4 weeks of
screening.

- CD4+ T-cell count ≥500 cells/µL.

- Undetectable HIV-1 RNA obtained at screening.

- ANC ≥2500/µL

- Platelet count ≥200,000/µL

Exclusion Criteria:

- Acute or chronic hepatitis B or hepatitis C infection.

- Active or recent (in prior 6 months) AIDS defining complication.

- Any cancer or malignancy within the past 5 years, with the exception of successfully
treated basal cell or squamous cell carcinoma of the skin or low grade (0 or 1) anal
or cervical dysplasia.

- Current diagnosis of NYHA grade 3 or 4 CHF, uncontrolled angina or arrhythmias.

- History or any features on physical examination indicative of a bleeding diathesis.

- Received HIV experimental vaccine within 6 months prior to screening, or any previous
gene therapy using an integrating vector.

- Use of chronic corticosteroids, hydroxyurea, or immunomodulating agents within 30 days
prior to screening.

- Use of Aspirin, dipyridamole, warfarin or any other medication that is likely to
affect platelet function or other aspects of blood coagulation during the 2 week
period prior to leukapheresis.

- Currently participating in another clinical trial or participation in such a trial
within 30 days prior to screening visit.

- Subjects who are currently taking maraviroc or have received maraviroc within 6 months
prior to screening.