Structured Treatment Interruptions in Chronic HIV Infection

• proportion of patients with CD4+ cell count above 500/mm3 at the end of follow-up (2 years) in the two treatment arms.
  

• occurrence of grade 3 or 4 adverse events (clinical and laboratory)
  
• proportion of patients with HIV-RNA < 400 copies/ml at the end of follow-up
  
• proportion of patients with CD4+ cell count > 350/mm3 at the end of follow-up
  
• rate of virological failure
  
• emergence of resistance
  
• HIV-related events.
  

Patients are randomized in a 1 to 1 ratio to continue their current antiretroviral regimen (Arm A) or to undergo structured treatment interruptions (STI) (Arm B) according to the following scheme: STIs of 1, 1, 2, 2 and 3 months each followed by a 3-month therapy period.

During STIs, therapy is resumed in the presence of an HIV-RNA rebound > 50,000 copies/ml or of a CD4+ T cell decline > 25% of the baseline count (> 35% for patients with CD4+ > 500/mm3 at randomization). After the first cycle, subsequent STIs are performed only if an HIV-RNA level < 400 copies/ml is reached after 2 months of therapy resumption.

At the time of treatment interruptions patients in arm B who are on treatment with non-nucleoside reverse transcriptase inhibitors suspend these drugs first and continue the treatment with the other drugs of the combination for 3 days if nevirapine-treated and for 6 days in case of previous efavirenz-based regimen.

Patients are seen at the clinical site every three months for arm A and monthly for arm B. On these occasions, blood samples are obtained for biochemical and viro-immunological assessments.

The toxicity grading scale of the AIDS Clinical Trial Group (ACTG) is used for the reporting of clinical and laboratory adverse events.

In arm B, plasma genotype is obtained in samples taken after 15 or 30 days of drug suspension.

Patients will discontinue the study in case of : early therapy resumption for 2 consecutive times (only arm B patients); acute retroviral syndrome (only for arm B patients); AIDS-defining event; severe adverse event; pregnancy; non-compliance; patient’ s request; physician’s decision.