Analytical Treatment Interruption (ATI) to Assess the Immune System's Ability to Control HIV in Participants Who Became HIV-infected During the HVTN 703/HPTN 081 AMP Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Analytical Treatment Interruption (ATI) to Assess the Immune System's Ability to Control HIV in Participants Who Became HIV-infected During the HVTN 703/HPTN 081 AMP Study (NCT04860323), a na na study. The primary outcome is Time to Meeting Criteria for ART Re-initiation.

2. Clinical Question

3. Trial Design

This is a completed, single-group study of analytical treatment interruption in participants who became HIV-infected during HVTN 703/HPTN 081. The registry reports enrollment of 13 and lists HIV infection as the condition. The study started on 2021-05-28, reached primary completion on 2025-02-04, and has a completed status. Phase is listed as NA. The sponsor is the HIV Vaccine Trials Network.

During the ATI, participants stopped taking ART and were monitored while off medication. According to the brief summary, ART was to be restarted if HIV levels showed that the immune system could not control HIV or if other ART restart criteria were met. The registry describes frequent testing of HIV levels and close monitoring of health. The intervention is named Analytical Treatment Interruption.

Participants had received VRC01 or placebo in the earlier HVTN 703/HPTN 081 study. The registry lists VRC01 10mg/kg, VRC01 30mg/kg, and placebo in the adverse-event groups, and describes the primary endpoint in relation to the previous treatment assignment. However, this ATI study is listed as single-group, with allocation and masking recorded as NA and none, respectively. The earlier group labels do not make the current ATI study a randomized comparison.

The registry lists 16 outcome measures and no analyses. Its primary endpoint concerns time to meeting criteria for ART re-initiation. Several secondary outcomes concern viral load, HIV-specific T-cell responses, antibody responses and functions, and dendritic-cell markers. A detailed statistical analysis plan, study-specific sample-size justification, and operational details beyond those stated in the registry record are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Participants (N= 2) with evidence of ARV use in ATI monitoring schedule are excluded from the analysis.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Time to Meeting Criteria for ART Re-initiation, measured over Measured through participant's last visit on Schedule 1 or 2, up to 27 months..

The primary endpoint is time to meeting criteria for ART re-initiation, measured in weeks. It concerns the time during the ATI until a participant meets the criteria to restart ART; it is not simply a count of participants who restarted medication. The registry describes a median and full range of weeks of ATI meeting the criteria, by the participants’ earlier HVTN 703/HPTN 081 treatment assignment.

Time-to-event endpoints are useful when the timing of an event matters and participants may be followed for different lengths of time. In general, the median describes the middle of the observed event-time distribution, while the range gives its lowest and highest observed values. Such summaries can describe the timing among participants with observed event times, but they do not by themselves explain why events occurred or establish a treatment effect.

The registry states that follow-up for this measure was through the participant’s last visit on Schedule 1 or 2, up to 27 months. It also states that participants with evidence of antiretroviral use during the ATI schedule are excluded, describing that group as N= 2. The registry record does not report the endpoint median, range, event counts, or a comparison estimate. The endpoint definition is available, but the posted results do not allow the timing distribution to be assessed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a time-to-event measure. The event is meeting criteria for ART re-initiation, not necessarily the act of restarting ART itself. The endpoint is stated in weeks of ATI. In general, time-to-event analysis focuses on both whether an event is observed and when it occurs. It can also account for participants whose event time is not observed during follow-up, but the statistical method used to handle such participants is not reported in the registry record.

What does a median time describe?

A median is a measure of the central position of an observed distribution. For an event-time outcome, it describes the time by which the middle of the relevant event-time distribution has reached the event, under the method used to estimate it. The registry specifies a median and full range, but does not provide either value. A range describes the spread from the smallest to the largest observed value; it does not show the shape of the distribution or how densely observations fall within it.

In general, a confidence interval expresses the uncertainty around an estimated quantity under a statistical model and its assumptions. It is distinct from a range, which describes observed values. No confidence interval for the primary endpoint is reported in the registry record. Without an estimate and an uncertainty measure, the precision of the endpoint cannot be assessed from the posted record.

Why does follow-up matter?

The endpoint timeframe is through the participant’s last visit on Schedule 1 or 2, up to 27 months. In time-to-event studies, follow-up may differ among participants. Someone who has not met the event criteria by their last visit has an event time that is not observed within that follow-up. Such observations are often described as censored in general statistical terminology. The registry record does not state whether any participants were censored, how censoring was handled, or which estimation method was used. Those details matter because time-to-event estimates rely on assumptions about follow-up and the observation process.

The outcome description identifies a median and full range, but does not specify a survival curve, a model, a test, or a hazard ratio for this primary endpoint. A hazard ratio, in general, compares event rates over time under a specified model; it is not the same as a difference in median times. No sponsor-reported hazard ratio for the primary endpoint appears in the registry record, and the record lists no analyses.

How should the prior treatment groups be understood?

The primary outcome is described by the prior HVTN 703/HPTN 081 treatment assignment: VRC01 or placebo. The current study is listed as single-group, and allocation is NA. These characteristics mean the registry does not describe a randomized allocation to the prior-treatment groups within the ATI study. In general, a comparison of groups that were formed in an earlier study can be affected by differences in who entered the ATI study, their clinical histories, follow-up, and other factors. The registry does not provide information sufficient to assess those factors or adjust for them.

When a study reports group comparisons, the model and its assumptions determine what the estimate represents. A statistical adjustment can address measured variables included in a model, but it cannot automatically remove all differences between groups. The registry record does not report an adjusted analysis, a specific model, or covariates for the primary endpoint. As a result, readers should not treat the earlier assignment labels as evidence that a causal comparison was performed in the present study.

What does over-dispersion mean in general?

Over-dispersion is a general issue for count outcomes when the observed variability is greater than expected under a model such as a simple Poisson model. It can make standard errors too small if ignored. This concept may be relevant to some count-based secondary outcomes, depending on their analysis, but the registry record does not specify count models or report results that would establish over-dispersion in this study. It should not be assumed to have occurred.

How should sample-size illustrations be read?

The record describes sample-size assumptions for planning illustrations, including a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect, and that time-to-event illustrations use a total number of events. These are planning conventions, not reported results from the ATI study. A planning illustration asks what sample size or event count might correspond to specified assumptions; it does not say how much power the completed study actually had. It is not observed power.

The record does not report a study-specific sample-size justification or the assumptions used to choose the enrolled sample. No observed effect estimate is reported for the primary endpoint in the record, so the planning illustrations cannot be used to recover the missing primary result. In general, precision depends on the amount and distribution of outcome information, not enrollment alone.

What methods are missing from the record?

The registry does not report the estimator for the median, the treatment of censored observations, a confidence interval method, a hypothesis test, covariate adjustment, or a detailed analysis plan. It also does not report interim analysis procedures. These omissions limit the ability to evaluate model assumptions, reproduce analyses, and understand how the endpoint would have been summarized if results were posted. The posted endpoint definition is informative, but it is not a full statistical methods description.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 16 outcome measures and no analyses. The primary outcome is time to meeting criteria for ART re-initiation. Named secondary outcomes include viral-load incidence at specified follow-up points, HIV-specific CD4+ and CD8+ T-cell responses, neutralizing antibody responses, antibody effector functions, and dendritic-cell activation and maturation markers. The record does not report how many hypotheses were tested or which outcomes were included in any formal inferential analysis.

Multiplicity arises when statistical conclusions are drawn across several outcomes, time points, groups, or tests. In general, testing many hypotheses can increase the chance of finding an apparently notable result by chance. Researchers may use a prespecified hierarchy, adjusted significance thresholds, or other strategies, but the registry record does not report a multiplicity strategy. It is not possible to determine from the outcome list alone whether any adjustment was planned or used.

The registry does not report methods for missing data, incomplete follow-up, censoring, or sensitivity analyses. These details are relevant to an endpoint measured through each participant’s last visit, particularly when observation periods may differ. The primary endpoint description says that participants with evidence of antiretroviral use during the ATI schedule are excluded and identifies N= 2 participants. The record does not describe other analysis populations, the handling of missing measurements, or whether all enrolled participants contributed to each secondary outcome.

Accordingly, readers cannot assess whether the analyses followed a prespecified plan, how missing outcomes were handled, or how inferential conclusions accounted for multiple outcomes. Those details are not reported in the registry record.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports serious adverse-event counts for three groups: VRC01 10mg/kg, VRC01 30mg/kg, and placebo. The corresponding numbers at risk are 5, 2, and 6, and the number affected by a serious adverse event is 0 in each group. The recorded death count is 0 in each group. These are descriptive counts in the registry record.

Other adverse events are reported separately. The numbers at risk are 5 for VRC01 10mg/kg, 2 for VRC01 30mg/kg, and 6 for placebo; the numbers affected are 5, 2, and 6, respectively. These figures indicate participants affected in the registry’s other-adverse-event category, not the number of distinct event types or their severity. The record does not list top serious adverse-event terms.

In general, a count of zero does not establish that an event is impossible or that groups have equivalent safety. The group sizes are limited, and this ATI study is not listed as a randomized comparison. The registry does not provide event-level descriptions, timing, duration, or a statistical comparison. The counts should therefore be read as the safety information recorded for these groups, not as a basis for a causal comparison.

12. What the Result Does, and Does Not, Mean

The registry record describes a monitored ATI in participants who acquired HIV during HVTN 703/HPTN 081. It identifies the main statistical question as time to meeting criteria for ART re-initiation and specifies a median and full range as the intended summary. It also states that participants with evidence of antiretroviral use during ATI monitoring are excluded from the endpoint analysis, identifying N= 2 participants in that category.

The record does not report the primary endpoint median or range, a confidence interval, event counts, or a comparison estimate. It therefore does not establish how long participants remained in ATI before meeting criteria, how variable those times were, or whether the endpoint differed by earlier treatment assignment. Outcome names and endpoint definitions are not outcome findings.

The study’s previous-treatment groups are described as VRC01 10mg/kg, VRC01 30mg/kg, and placebo. Because the ATI study is listed as single-group and allocation is NA, those labels do not constitute a randomized comparison within this study. Even if group-specific outcome values were available, interpretation would require attention to group comparability, follow-up, and the analysis methods.

The safety record reports no serious adverse events and no deaths in the listed groups, while reporting other adverse events among participants in each group. Those descriptive figures do not establish comparative safety or rule out events that were not observed in the enrolled participants. The registry lists 16 outcome measures but no analyses, and does not report multiplicity procedures, missing-data methods, or a detailed statistical plan.

The findings that can be stated from this record are therefore limited to the study design, outcome definitions, and recorded safety counts. The absent primary endpoint results prevent assessment of the main statistical question. No conclusion about treatment benefit or lack of benefit follows from the missing results.

13. Why This Trial Matters Statistically

This study raises a statistical question about the timing of ART restart criteria during a monitored treatment interruption. Timing is distinct from simply recording whether a participant met criteria: two participants might both meet criteria but do so at different points in follow-up. A time-to-event endpoint can preserve that timing information, provided the analysis and follow-up are described clearly.

The record also illustrates why endpoint definitions and results must be distinguished. It gives the primary endpoint, its unit, the intended median and range, and the follow-up window up to 27 months. But the endpoint values themselves are not reported. A detailed definition helps explain what investigators intended to measure; without estimates and uncertainty, it cannot answer how the observed participants’ times were distributed.

The relationship between the ATI study and the earlier HVTN 703/HPTN 081 assignments is another important statistical consideration. The current study is listed as single-group, while participants are described according to earlier VRC01 or placebo assignment. This design context matters when interpreting any group-level comparison, because the registry does not characterize the assignment as a randomized comparison within the ATI study.

The safety counts provide a further example of why denominators and study design matter. The registry reports group-specific numbers at risk, serious adverse-event counts, other adverse-event counts, and deaths. These are useful descriptions, but small groups and the absence of a randomized comparison limit comparative interpretation.

Finally, the record lists 16 outcome measures and no analyses. Statistical reporting of estimates, uncertainty, missing-data handling, and multiplicity procedures would be needed to evaluate the strength and reliability of conclusions. Sample-size planning illustrations, where presented, are not observed power and do not replace the missing endpoint results or a study-specific design justification.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The primary limitation for interpretation is that the registry record does not report the primary endpoint results. Although it specifies time to meeting criteria for ART re-initiation, the median, full range, event counts, and uncertainty estimates are absent. This prevents evaluation of the main outcome’s distribution and precision.

The endpoint population description states that participants with evidence of antiretroviral use during ATI monitoring are excluded and identifies N= 2 participants. The record does not describe other exclusions, incomplete follow-up, or how participants without an observed event were handled. The follow-up window is through the last visit on Schedule 1 or 2, up to 27 months, but the record does not give participant-level follow-up information.

The three prior-treatment labels do not create a randomized comparison in this single-group ATI study. The registry does not report methods for accounting for group differences or other potential confounding. It also does not provide a detailed statistical analysis plan, model specification, interim analysis information, or sample-size justification. Multiplicity and missing-data methods are not reported in the registry record.

The safety counts are limited to the group-level figures recorded. The registry does not list top serious adverse-event terms and does not provide event-level details or a formal comparative analysis. The small group counts and non-comparative design limit what can be inferred from these descriptive numbers. These limitations apply to interpretation of the registry record and do not resolve outcomes that are not reported there.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Analytical Treatment Interruption (ATI) to Assess the Immune System's Ability to Control HIV in Participants Who Became HIV-infected During the HVTN 703/HPTN 081 AMP Study — NCT04860323.
• Registry record last updated 2026-03-13; status last verified 2026-02.
• Results first posted 2026-03-13.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT04860323 is a completed, single-group analytical treatment interruption study sponsored by the HIV Vaccine Trials Network. The registry reports enrollment of 13, a start date of 2021-05-28, and primary completion on 2025-02-04. Participants had acquired HIV during HVTN 703/HPTN 081 and had received VRC01 or placebo in that earlier study.

The primary endpoint is time in weeks to meeting criteria for ART re-initiation, summarized as a median and full range through the last visit on Schedule 1 or 2, up to 27 months. The registry record does not report the primary endpoint values or analyses. It lists 16 outcome measures and no analyses.

For the listed groups, the registry reports 0 participants affected by serious adverse events and 0 deaths in each group, with other adverse events recorded among participants in each group. The record does not report a study-specific sample-size justification, detailed statistical analysis plan, multiplicity method, or missing-data method.