A Randomized, Multicenter Trial to Determine Whether Induction Therapy Followed by Treatment Interruption is Superior to Induction Therapy Alone in the Treatment of Primary HIV Infection (PHI): The Structured Treatment Interruption (STI) Study

Initiation of treatment during acute HIV infection seems to result in greater suppression of viral replication than noted during chronic infection and better recovery of certain CD4 subpopulations. However, it is difficult for patients treated during acute infection to maintain long-term continuous antiretroviral (ARV) treatment because of difficulty adhering to complicated medication regimens, drug-related toxicities, and cost of medications. Acutely infected patients who have undergone early initiation of treatment followed by structured treatment interruptions (STIs) appear to have lower off-treatment viral loads than historical controls. This study will evaluate whether effective ARV treatment during acute and early HIV infection followed by STI will result in lower viral setpoints than would otherwise be expected.

This trial will have 2 steps and will last for a maximum of 104 weeks. Participants will either enter Step 1 and continue on to Step 2 or enter Step 2 directly. During Step 1, participants with acute or early HIV infection will be given 24 weeks of ARV therapy. Participants may take any combination of FDA-approved ARV medications that they and their doctors select. Participants will have study visits at study entry and Weeks 1, 4, 8, and 20. After 24 weeks on Step 1, participants may enroll in Step 2.

Participants in Step 1 and people with early or acute HIV infection who began ARV treatment within 21 days of diagnosis and have had no more than 1 year of treatment may enroll in Step 2. During Step 2, participants will be randomly assigned to one of two study arms:

• Arm 1: Participants will continue taking ARV therapy for 16 weeks and then stop ARVs for 64 weeks.
• Arm 2: Participants will stop ARVs for 4 weeks, take ARVs for 8 weeks, stop ARVs for 4 weeks, take ARVs for 8 weeks, and then stop ARVs for 56 weeks.

Participants in both study arms will restart ARVs regardless of STI duration if their viral load is above 50,000 copies/ml, they progress to CDC category C disease, or their CD4 count falls below 350 cells/mm3 or declines more than 50% from the last on-treatment CD4 level.