Immunotherapy with canarypox vaccine and interleukin-2 for HIV-1 infection: termination of a randomized trial.

Objectives: To determine whether immunotherapy of chronic HIV-1 infection can prevent or attenuate viremia upon antiviral discontinuation.

Design: This was a Phase II randomized, partially double blinded, 2x2 factorial study of three steps of 12 wk/step. Step I involved four groups: (1) vaccine placebo, (2) vaccine (ALVAC, vCP1452), (3) placebo + interleukin 2 (IL-2), and (4) vaccine + IL-2. Step II involved a 12-wk diagnostic treatment interruption (DTI). Step III involved an extension of the DTI for an additional 12 wk.

Setting: The Weill-Cornell General Clinical Research Center.

Participants: Chronically infected HIV-1 positive adults with undetectable HIV-1 levels and > 400 CD4+ T cells/microl.

Interventions: An HIV canarypox vaccine (vCP1452) and vaccine placebo, administered every 4 wk for four doses, and low-dose IL-2 administered daily for 12-24 wk.

Outcome measures: Primary endpoints: (1) Proportion of participants with undetectable plasma HIV RNA during trial Step II, (2) mean log10 HIV RNA copies/ml ([HIV]) from weeks 21-25, and (3) proportion of individuals eligible for trial Step III.

Results: 44 participants were randomized, but 16 withdrew or were withdrawn before completing Step II. As all participants underwent viral relapse in Step II, the study was terminated after 28 participants completed Step II. Among the four groups, there was no difference in mean [HIV] or the proportion of individuals with < log10 4.48 HIV; no difference between the mean [HIV] of the two groups that received ALVAC (n = 17) versus placebo (n = 11); and no significant difference between the mean [HIV] of the two groups that received IL-2 (n = 11) versus placebo (n = 17).

Conclusions: Neither ALVAC (vCP1452) nor low-dose daily IL-2 nor their combination prevented the relapse of viremia upon discontinuation of antiviral therapy.