Inferiority of IL-2 alone versus IL-2 with HAART in maintaining CD4 T cell counts during HAART interruption: a randomized controlled trial.

Objective: To evaluate whether interleukin (IL)-2 in patients with chronic HIV infection can maintain CD4 T cell counts during 6 months of HAART interruption.

Design: Prospective, randomized, controlled, open-label phase II noninferiority trial comparing IL-2 with HAART interruption or continuous HAART.

Methods: Forty-one IL-2-experienced (three or more prior cycles) HIV-1-infected adults with CD4 cell count at least 500 cells/microl were randomized in the ratio 2: 1 to interrupted (I = 27) or continuous (C = 14) HAART for 6 months following an initial IL-2 cycle. Subsequent IL-2 cycles were triggered by CD4 T cell counts less than 90% of baseline. Immune, metabolic, and quality of life indices were compared (Mann-Whitney and Fisher's exact tests), defining noninferiority as a percentage difference (C- I) in treatment success (CD4 T cells > or =90% of baseline at 6 months) with a 95% confidence interval (CI) lower limit greater than -20%.

Results: Demographic and immune parameters were similar between the groups at baseline. Median CD4 T cell count, HIV viral load, and treatment success differed significantly at 6 months (I: 866 cells/microl, 39,389 copies/ml, 48.1%; C: 1246 cells/microl, <50 copies/ml, 92.3%; P < or = 0.001). Group I was inferior to C (% difference = -44.2%; 95% CI: -64.2%, -11.2%; P = 0.013). Minor statistically significant differences in HgbA1c and energy level occurred at 6 months (I > C). Following HAART interruption, single cases of acute retroviral syndrome, secondary syphilis, non-Hodgkin's lymphoma, and Kaposi's sarcoma recurrence were observed.

Conclusion: IL-2 alone was inferior to IL-2 with HAART in maintaining baseline CD4 T cell counts. HAART interruption had a small impact on metabolic parameters and quality of life.