A randomized trial of interleukin-2 during withdrawal of antiretroviral treatment

In HIV-infected individuals on antiretroviral treatment with viral suppression, structured treatment interruptions are designed to allow exposure to endogenous HIV antigens and to thereby boost HIV-specific immunity. AIDS Clinical Trials Group A5132 was an exploratory 2-arm randomized trial that evaluated two 4-week treatment interruptions in combination with 2 strategies for administering interleukin-2 (IL-2): 2.0 million international units of IL-2 subcutaneously daily during the final 2 weeks of treatment interruption and the first week of treatment reinitiation (arm A), or 4.5 million international units of IL-2 subcutaneously twice a day during the first 5 days of treatment reinitiation (arm B). Twenty-one subjects with HIV-1 RNA <50 copies/mL and CD4+ T cell counts ≥300 (median 615) cells/mm³ were randomized. The primary endpoint was the viral setpoint measured 11-12 weeks after a third treatment interruption (observed for 7 Arm A and 9 Arm B). The median HIV-1 RNA setpoints were 4.3 and 4.5 log₁₀ copies/mL for Arm A and Arm B, respectively; there was no evidence of a difference between arms (P=0.50, rank-sum test, worst rank for unobserved viral setpoint). The current study, the first to evaluate IL-2 during repeated short-term treatment interruptions, revealed no evidence for augmentation of HIV immunity. Viral setpoints were similar to historical controls, emphasizing the need for new strategies to enhance HIV-specific immunity.