Viral Suppression After Analytic Treatment Interruption in Thai Patients Who Initiated Highly Active Antiretroviral Therapy During Acute HIV Infection

This is a two step open label study of ATI in patients who initiated ART in the earliest detectable stage (Fiebig I) of HIV infection. In step I, eight subjects will discontinue ART for a period of up to 24 weeks. An interim assessment will be conducted after all eight

subjects in step I complete follow-up for 12 weeks. If at least one out of eight subjects maintains viral suppression (HIV-1 RNA < 50 copies/ml) at 12 weeks, then the study will proceed to step 2, in which 7 additional subjects (maximum total sample size of 15) will undergo ATI. The primary endpoint is proportion of subjects who maintain viral suppression at 24 weeks post ATI. Subjects will be monitored frequently for disease progression using clinical, immunological and virological criteria. ART will be re-initiated immediately for any subjects who meet pre-defined criteria for disease progression.

Parent Study Cohort

This is a sub-study of the protocol "Establish and characterize an acute HIV infection cohort in a high-risk population" (SEARCH 010, RV254, WRAIR 1494) implemented at the Thai Red Cross AIDS Research Center in Bangkok, Thailand. From April 2009 through February 2014 the cohort had enrolled 150 patients with acute infection and 145 (97%) are still in active follow-up. All patients in the cohort are offered ART at the time of enrollment through a separately funded protocol; all 145 subjects (100%) in active follow-up are currently on ART. The median age (range) of the cohort is 28 (18-57) years and 90% are men who have sex with men (MSM).

The cohort currently has 50 volunteers who started ART during Fiebig Stage 1, of whom 24 have been on ART for > 24 months and have HIV-1 < 50 copies/ml. Another 13 volunteers have been on ART 6-24 months with undetectable HIV-1 RNA.

During the period of co-enrollment in this substudy, no additional biological specimens will be collected as part of the RV254/SEARCH 010 protocol. Data and samples from this substudy will be shared with the parent protocol.

Criteria to reinitiate ART after ATI

The criteria to restart ART after ATI are designed to protect the subjects from any possible clinical, immunological, or virological adverse effects in the event that their VL rebounds while off ART. The viral load (VL) criterion of > 1,000 copies/ml was chosen because clinical symptoms of HIV infection or significant decline in CD4 count would not be expected at this low level of viremia. The Fiebig I patients in the SEARCH 010 cohort had a median (range) HIV-1 RNA of 4.8 (2.8-5.7) log10copies/ml, at a median (range) of 12 (4-40) days after exposure to HIV, prior to initiation ART and have therefore already been exposed to high levels of plasma virus during acute infection while maintaining low or no detectable HIV proviral reservoirs.

In addition, the ANRS Visconti study found that patients who are virologic controllers (sustained VL < 50 copies/ml) after ATI may initially and transiently have VL above detection. Of 240 tests performed after treatment interruption in those who were subsequently virologic controllers or PTC, 2% had VL > 400 copies/ml and 18% had VL between 50 and 400 copies/ml. Therefore, low-level viremia may not always be indicative of viral rebound and can potentially reverse.

Specific criteria for re-initiation of ART after ATI are:

1. HIV-1 RNA above 1,000 copies/ml on 2 consecutive determinations at least 3 days apart. OR
2. HIV-1 RNA rise of ≥ 0.5 log10copies/ml per day provided that the last HIV-1 RNA is above 1000 copies/ml OR
3. A single HIV-1 RNA above 10,000 copies/ml OR
4. CD4+ T-cell counts below 350 cells/mm3 on 2 consecutive determinations at least 2 weeks apart. OR
5. CD4+ T-cell count decline of > 50% from baseline prior to ATI. OR
6. Clinical progression to CDC Category B or C disease. OR
7. Diagnosis of Acute Retroviral Syndrome. OR
8. Pregnancy OR
9. Subject requests re-initiation of ART.