This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Extension Study of the Safety and Efficacy of Multi-dose Intravenous ARC-520 in Patients With Chronic Hepatitis B (HBV) Infection (NCT02738008), a na phase 2 study. The primary outcome is Percentage of Initial Responders to ARC-520 Therapy Achieving a 1-log Reduction in HBsAg at Week 36 Compared to Baseline.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02738008 |
| Phase | Phase 2 |
| Condition | Hepatitis B |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 12 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Arrowhead Pharmaceuticals |
| Results posted | Yes |
2. Clinical Question
Population
People with chronic hepatitis B infection who had initially responded to ARC-520 therapy in the parent studies were the population of interest for the primary endpoint. The registry defines an initial responder as someone with a ½ log or greater reduction in serum HBsAg from baseline to Day 71 ± 3 days in the primary Heparc-2002 or Heparc-2003 study. The registry lists an enrollment of 12.
Intervention
The extension planned multiple intravenous administrations of ARC-520, starting at 2 mg/kg, alongside ongoing entecavir or tenofovir. The brief description states that participants would receive 9 doses once every 4 weeks. The study was open-label.
Comparator
There was no concurrent control group in this single-group study. Participants were not assigned to a randomized comparison, and the registry does not describe a like-for-like control arm. Entecavir or tenofovir accompanied ARC-520; they are not described as comparator groups for estimating ARC-520’s effect.
Primary question
The primary endpoint asked what percentage of initial responders achieved a 1-log reduction in HBsAg at Week 36 compared with baseline. The registry states that the study ended before any participant reached Week 36 of treatment, so the endpoint could not be analyzed.
The question is therefore about a planned biomarker response at a specified follow-up time, among a selected group defined by response in earlier studies. It is not a question about the proportion of all people with chronic hepatitis B who would respond, because initial responders form a narrower population. Nor does the single-group design, by itself, establish how outcomes would compare with an alternative treatment or with no ARC-520.
The outcome definition also depends on two stages: first, meeting the initial-responder definition in a parent study, and then reaching the specified HBsAg reduction at Week 36 in the extension. The registry record gives the definition and planned assessment, but no Week 36 outcome result. It therefore does not answer whether participants met the primary endpoint.
3. Trial Design
This was a Phase 2, multicenter extension study of multi-dose intravenous ARC-520 in people with chronic hepatitis B infection. Its official title describes ARC-520 in combination with entecavir or tenofovir. The registry lists a single-group model, no allocation to comparative arms, and no masking. The study was open-label, meaning treatment assignment was not masked from participants and study personnel as described in the record.
The planned regimen was multiple ARC-520 administrations starting at 2 mg/kg, together with entecavir at 0.5 or 1.0 mg/day or tenofovir at 300 mg/day. The brief description says participants would receive 9 doses once every 4 weeks and be evaluated for safety and efficacy. These details describe the planned regimen; the record does not establish that every planned dose was received by every participant.
The registry lists an enrollment of 12. It records a start in 2016-03, primary completion in 2016-12, and a status of terminated. Most importantly for interpreting the primary endpoint, the registry says termination occurred before any participant reached Week 36 of treatment. The primary endpoint consequently could not be analyzed.
The primary outcome focused on initial responders to ARC-520 therapy, as defined from the parent Heparc-2002 and Heparc-2003 studies. It asked whether they achieved a 1-log reduction in HBsAg at Week 36 compared with baseline. The registry also lists outcomes concerning treatment-emergent adverse events, serious adverse events, and HBsAg loss among initial responders over time.
Because this was a single-group, open-label extension without a concurrent control, its design does not support a randomized comparison of ARC-520 with another treatment. The registry record does not report a protocol rationale for the design, a sample-size justification, or further operational details beyond the regimen and study description.
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.
Before assignment: No participants were enrolled from the Heparc-2002 or Heparc-2003 placebo groups.
Overall Study
| Stage | Heparc-2002: ARC-520 1.0 mg/kg | Heparc-2002: ARC-520 2.0 mg/kg | Heparc-2003: ARC-520 2.0 mg/kg |
|---|---|---|---|
| STARTED | 1 | 6 | 5 |
| COMPLETED | 0 | 0 | 0 |
| NOT COMPLETED | 1 | 6 | 5 |
Reasons for not completing this period:
| Reason | Heparc-2002: ARC-520 1.0 mg/kg | Heparc-2002: ARC-520 2.0 mg/kg | Heparc-2003: ARC-520 2.0 mg/kg |
|---|---|---|---|
| Study Terminated by Sponsor | 1 | 5 | 3 |
| Adverse Event | 0 | 1 | 2 |
Analysis population for the primary outcome, as defined in the registry: The study was terminated prior to any participant reaching Week 36 of treatment; therefore, this outcome measure could not be analyzed.
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.
| Characteristic | Unit | Heparc-2002: ARC-520 1.0 mg/kg | Heparc-2002: ARC-520 2.0 mg/kg | Heparc-2003: ARC-520 2.0 mg/kg | Total |
|---|---|---|---|---|---|
| Participants analysed | 1 | 6 | 5 | 12 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 | 5 | 5 | 11 |
| Age, Categorical: >=65 years | Participants | 0 | 1 | 0 | 1 |
| Sex: Female, Male: Female | Participants | 0 | 5 | 2 | 7 |
| Sex: Female, Male: Male | Participants | 1 | 1 | 3 | 5 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Initial Responders to ARC-520 Therapy Achieving a 1-log Reduction in HBsAg at Week 36 Compared to Baseline, measured over Baseline, Week 36.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was the percentage of initial responders to ARC-520 therapy who achieved a 1-log reduction in HBsAg at Week 36 compared with baseline. HBsAg is hepatitis B surface antigen; the registry uses its level as the biomarker measured for this outcome. The endpoint therefore concerns a change in a laboratory marker, not a direct measure of how participants felt or functioned.
The endpoint’s population is restricted by the initial-responder definition. Participants had to show a ½ log or greater reduction in serum HBsAg from baseline to Day 71 ± 3 days in the primary Heparc-2002 or Heparc-2003 study. Baseline for that definition is the average of pre-dose values. The Week 36 outcome then asks whether this selected group achieved the specified reduction compared with baseline during the extension.
As a general statistical point, a prespecified endpoint gives a study a defined target for summarizing outcomes. A biomarker endpoint can describe a biological response, while the relevance of that response to other outcomes requires evidence and should not be assumed from the biomarker result alone.
The registry states that the study was terminated before any participant reached Week 36 of treatment. As a result, the primary outcome measure could not be analyzed. No percentage achieving the endpoint, estimate of change, or uncertainty interval is reported for this primary question. The endpoint is therefore a planned measure, not a reported efficacy result from the extension.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive fact is that the primary endpoint has no analyzed result in the registry record. Although the registry specifies a Week 36 HBsAg response among initial responders, it states that the study ended before any participant reached that assessment. The endpoint cannot therefore establish the observed percentage achieving the response, the amount of change in HBsAg, or the precision of an estimate.
This is not equivalent to observing no responses. No participant reaching the scheduled assessment means the endpoint was unavailable for analysis; it does not show that participants failed to achieve the reduction. The distinction matters because a missing endpoint result cannot be read as a negative outcome. It also cannot be treated as evidence of benefit. The appropriate conclusion is limited to the lack of an analyzable Week 36 result.
The study’s single-group design also limits what could be learned even if the endpoint had been observed. Without a concurrent control group, a change during follow-up could not be separated by randomization from other influences, such as the course of the underlying condition or ongoing background therapy. This is a general limitation of uncontrolled comparisons, not a claim that any particular alternative explanation occurred in this study. The registry does not report a comparative effect estimate.
The endpoint concerns initial responders, not every participant with chronic hepatitis B. Its definition relies on response measurements in the parent studies, and the primary question concerns the subsequent Week 36 outcome in the extension. Results for such a selected population would not automatically describe people who did not meet the initial-responder definition. In this record, no Week 36 result is available for either the selected population or the wider group.
The registry lists adverse-event counts for groups identified by parent study and ARC-520 dose. Those safety summaries are distinct from the unavailable primary endpoint and should be read as descriptive counts, not as a treatment comparison. The record does not provide an inferential analysis comparing those groups, and the groups are not a like-for-like randomized control comparison.
General statistical context: an estimate is more informative when its uncertainty is also reported. A confidence interval describes a range of values compatible with the data and the method used; it does not correct for a missing endpoint or establish causation. The registry record reports no primary endpoint estimate or confidence interval. Nor does it report a primary endpoint hypothesis test. Thus, there is no basis in the record for describing the planned Week 36 result as statistically significant or not statistically significant.
Overall, the posted results document a planned regimen and a study termination that prevented the primary assessment. They do not quantify the primary biomarker response, compare ARC-520 with a control treatment, or establish what the result would have been had the study continued.
9. Statistical Methods Explained
The registry record describes a Phase 2, single-group, open-label extension. It specifies the planned primary outcome and gives limited safety counts, but reports no primary endpoint analysis. The statistical interpretation should therefore distinguish between the endpoint that was planned and outcomes that were actually analyzed. The concepts below provide general context for reading this type of record; they are not claims about unreported methods used in the study.
What does a single-group design estimate?
In general, a single-group study describes outcomes among participants receiving the study regimen. If outcomes are measured before and after treatment, the observed change can describe what happened over time in that group. Without a concurrent control group, however, the change does not isolate the effect of the study treatment from other possible influences. Random allocation to a control group can help make groups comparable on average; this extension had no such comparison according to the registry.
Here, the primary endpoint was a percentage of initial responders meeting a biomarker threshold at a later assessment. Since the registry says no participant reached the Week 36 assessment, even that descriptive percentage could not be calculated from the endpoint. The absence of a comparison group is a separate design limitation: it would constrain causal interpretation even if the endpoint had been observed.
What does the endpoint threshold mean?
The primary outcome uses a defined reduction in HBsAg relative to baseline. A threshold endpoint classifies participants according to whether their measured change reaches a stated boundary. In general, such an outcome can be straightforward to communicate, but it does not show how far above or below the threshold each person’s measurement lies. A continuous measurement, by contrast, can retain information about the size of each change, subject to the analysis approach.
The endpoint is restricted to initial responders, whose earlier response is defined using a ½ log or greater reduction by Day 71 ± 3 days in the parent studies. That selection defines the population to which the planned Week 36 percentage would apply. A result in this selected group would not automatically generalize to participants who did not meet that definition. In this record, the planned percentage was not analyzed.
How should an estimate and its precision be read?
General statistical explanation: an estimate is a summary of the observed data, while a confidence interval conveys uncertainty around that estimate under the analysis assumptions. A narrower interval generally indicates greater precision, though precision alone does not establish that an effect is clinically important or causal. A p-value, when reported, describes how incompatible the data are with a specified null model under the assumptions of the test; it is not the probability that a treatment works.
The registry record reports no estimate, confidence interval, or p-value for the primary endpoint. Without an analyzed endpoint, there is no precision measure to interpret. A sample-size calculation based on a hypothetical or previously observed effect would be a planning exercise, not evidence that the study had a particular probability of detecting an effect. The registry record does not report a sample-size justification or the assumptions of a study-specific power calculation.
Why can over-dispersion matter?
General statistical explanation: over-dispersion occurs when observed variability in count data is greater than a chosen statistical model expects. If a model assumes less variability than the data actually contain, standard errors can be too small and uncertainty can appear understated. Analysts may use methods that allow extra variability, but the appropriate approach depends on the outcome and data structure.
The registry record does not report a model for the primary endpoint, an over-dispersion assessment, or a statistical analysis plan. The primary outcome is described as a percentage, but its unavailable Week 36 data do not permit assessment of the distribution or variability. It would not be appropriate to infer which model or variance adjustment was planned.
What do the safety counts represent?
General statistical explanation: event counts and participant counts answer different questions. A participant-level count of people with at least one event does not convey the total number of events if an individual can experience more than one. A denominator indicates how many participants were included or at risk for the summary, but the precise event definition and observation window are also needed to interpret incidence over time.
The registry lists participants at risk and participants affected for serious and other adverse events in groups labeled by parent study and ARC-520 dose. These are descriptive summaries. The record does not report a statistical comparison of these groups, and they should not be treated as randomized comparator arms. The serious-event summaries list zero affected participants in each group; this describes the listed groups and does not establish that the risk is absent.
More generally, safety interpretation depends on exposure duration, event definitions, completeness of follow-up, and whether events are counted by participant or by occurrence. The registry record does not provide enough detail to reconstruct an event rate over person-time or to determine a comparative risk. The counts should therefore be read as the reported participant counts, with these limits in mind.
What can be concluded from an unavailable endpoint?
General statistical explanation: when a planned assessment is not reached, the endpoint is not simply a zero or a negative response. It is an unobserved outcome for the intended assessment time. Missingness can affect interpretation when it occurs after study entry, and methods for handling it depend on why observations are missing and on the analysis population. Methods such as imputation require assumptions; they cannot restore information without those assumptions.
For this study, the registry gives a specific reason the primary endpoint was unavailable: termination occurred before any participant reached Week 36. It does not report an imputation method or an analysis of the primary endpoint. The record therefore supports neither an estimate at Week 36 nor an account of how missing Week 36 observations were handled.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary endpoint concerning a 1-log reduction in HBsAg at Week 36 among initial responders. It also lists secondary outcomes concerning treatment-emergent adverse events, serious adverse events, and HBsAg loss over time. The record reports no analyses for the primary endpoint and no analyses overall. It does not describe a statistical plan for controlling the chance of false-positive findings when evaluating multiple outcomes or time points.
As a general statistical point, testing many outcomes or time points can increase the chance that at least one result appears notable by chance. A prespecified hierarchy, adjustment procedure, or other multiplicity strategy can address that issue, but the registry record does not report whether such a strategy was planned. Because no primary endpoint analysis is reported, there is no reported inferential result whose multiplicity adjustment can be assessed.
The record states that the study was terminated before any participant reached Week 36, so the primary endpoint could not be analyzed. It does not report a missing-data method, an imputation procedure, or an analysis population for that endpoint. The stated reason for the unavailable assessment is the study’s termination before the scheduled time, rather than a reported pattern of individual participant withdrawals.
General statistical context: an analysis population defines which participants contribute to a particular estimate. Intention-to-treat, per-protocol, and safety populations can differ in their inclusion rules, and those rules should be stated before results are interpreted. The registry record does not specify such populations for the primary endpoint. It is therefore not possible to determine from the record whether the planned endpoint analysis would have included all enrolled participants, only those meeting the initial-responder definition, or another defined set beyond the population description given.
The safety summaries do provide group-specific numbers at risk and affected, but the record does not give further analysis-population rules or missing-data handling for those summaries. These reporting gaps limit assessment of completeness and comparability; they should not be filled by assumptions about the protocol.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Heparc-2002: ARC-520 1.0 mg/kg | 0 | 1 | 0.0% |
| Heparc-2002: ARC-520 2.0 mg/kg | 0 | 6 | 0.0% |
| Heparc-2003: ARC-520 2.0 mg/kg | 0 | 5 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Heparc-2002: ARC-520 1.0 mg/kg | 1 of 1 |
| Heparc-2002: ARC-520 2.0 mg/kg | 4 of 6 |
| Heparc-2003: ARC-520 2.0 mg/kg | 4 of 5 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Heparc-2002: ARC-520 1.0 mg/kg | Heparc-2002: ARC-520 2.0 mg/kg | Heparc-2003: ARC-520 2.0 mg/kg |
|---|---|---|---|---|
| Anaemia | Blood and lymphatic system disorders | 0 of 1 | 0 of 6 | 2 of 5 |
| Nausea | Gastrointestinal disorders | 0 of 1 | 0 of 6 | 2 of 5 |
| Chest discomfort | General disorders | 0 of 1 | 0 of 6 | 2 of 5 |
| Pyrexia | General disorders | 1 of 1 | 0 of 6 | 1 of 5 |
| Flushing | Vascular disorders | 0 of 1 | 0 of 6 | 2 of 5 |
| Chills | General disorders | 1 of 1 | 0 of 6 | 0 of 5 |
| Fatigue | General disorders | 0 of 1 | 0 of 6 | 1 of 5 |
| Malaise | General disorders | 0 of 1 | 1 of 6 | 0 of 5 |
| Hordeolum | Infections and infestations | 0 of 1 | 1 of 6 | 0 of 5 |
| Back pain | Musculoskeletal and connective tissue disorders | 0 of 1 | 1 of 6 | 0 of 5 |
The registry lists serious and other adverse-event counts for three groups labeled by parent study and ARC-520 dose. For serious adverse events, the listed numbers at risk are 1, 6, and 5, and the numbers affected are 0 in each group. For other adverse events, the numbers at risk are 1, 6, and 5, while the numbers affected are 1, 4, and 4, respectively. These are participant counts, not percentages or event totals.
The labels identify Heparc-2002 at 1.0 mg/kg, Heparc-2002 at 2.0 mg/kg, and Heparc-2003 at 2.0 mg/kg. They are not randomized comparison arms for this extension. The registry does not report an inferential comparison between them, and their counts should not be interpreted as demonstrating that one dose or parent study had a different risk.
A zero in the serious-event column means no affected participants are listed for that group in the registry summary. It does not prove that serious events cannot occur, and the small group counts provide limited information about uncommon outcomes. The record does not provide exposure-adjusted rates, event timing, or further detail about the observation windows. Deaths are not reported in these group summaries. The counts therefore support a descriptive reading only, not a conclusion about comparative safety.
12. What the Result Does, and Does Not, Mean
The registry record establishes that the study was intended to evaluate repeated intravenous ARC-520 alongside entecavir or tenofovir in people with chronic hepatitis B. It also establishes that the planned primary question concerned a Week 36 HBsAg response among participants who had initially responded in the parent studies. The reported termination before any participant reached Week 36 means that this primary outcome could not be analyzed.
That result does not show that the response rate was zero. It also does not show that the response target was met. The endpoint was not observed at the planned time, so the posted record does not estimate the proportion achieving the reduction. There is no primary endpoint estimate or reported precision to interpret.
The safety information is separate: the record lists numbers of participants at risk and affected for groups identified by parent study and ARC-520 dose. These counts describe the registry summaries but do not constitute a randomized comparison. They do not establish that a treatment caused or prevented an event, and the record provides no comparative statistical analysis.
The extension’s single-group design would limit causal interpretation even if its primary endpoint had been available. A change observed within one group cannot by itself distinguish a treatment effect from other influences over time. The absence of a concurrent control is especially important when interpreting a biomarker change, because the record does not show what would have happened to a comparable group without the extension regimen.
General context: a biomarker outcome can document a change in a measured biological marker, but it should not be assumed to establish a change in symptoms or other clinical outcomes. The registry record does not report a primary endpoint result or establish a relationship between the planned HBsAg outcome and other outcomes in this extension. The most defensible reading is therefore narrow: the study planned a biomarker assessment, but termination prevented that assessment from answering the primary question.
13. Why This Trial Matters Statistically
This study matters statistically because it shows how the timing of follow-up can determine whether a prespecified question is answerable. The primary endpoint depended on participants reaching Week 36. The registry states that termination occurred before any participant reached that point, leaving the planned endpoint without an analysis. A clearly defined endpoint is useful, but a definition alone cannot provide evidence when the required observation is unavailable.
The record also illustrates why a planned biomarker response and a reported result must be kept distinct. The endpoint specifies a threshold and a population of initial responders, but neither detail supplies an observed response percentage. Treating the planned endpoint as though it were an outcome would confuse study design with evidence.
The single-group structure is another important statistical feature. Even with complete follow-up, results from a group receiving ARC-520 with ongoing antiviral therapy would describe that group’s outcomes, not a randomized contrast against an alternative. The absence of a concurrent control constrains causal interpretation and makes it important not to present within-group outcomes as comparative treatment effects.
Finally, the registry’s safety counts demonstrate the value of reporting denominators alongside affected participants, while also showing the limits of sparse descriptive summaries. Counts can be read accurately without converting them into unsupported claims about comparative risk. The record does not provide an inferential analysis or enough detail to reconstruct exposure-adjusted rates.
These points are broadly relevant to clinical research: interpretation depends on what was measured, in whom, at what time, and under what design. In this case, the planned primary assessment was not reached, and the design did not include a randomized control. Those features define the limits of what the registry record can answer.
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 most direct limitation is that the primary endpoint could not be analyzed. The registry states that the study was terminated before any participant reached Week 36 of treatment. There is consequently no reported primary response percentage, estimate of HBsAg change at that assessment, or uncertainty interval.
The study was a single-group, open-label extension with no randomized control comparison. Any observed outcomes would therefore have limited ability to separate the regimen’s effect from other influences over time. The registry record does not report a comparative effect estimate.
The primary endpoint applied to initial responders defined using outcomes in the parent Heparc-2002 and Heparc-2003 studies. This selected population is narrower than all people with chronic hepatitis B, and findings from it would not automatically generalize to people who did not meet the initial-responder definition. In this record, the Week 36 endpoint is unavailable even for that selected group.
The registry lists an enrollment of 12, but does not report a sample-size justification or a study-specific statistical analysis plan. It also does not report the intended analysis population, a method for handling missing primary outcome data, or a multiplicity strategy. These omissions limit evaluation of how the planned analysis would have been conducted.
The safety summaries are descriptive and are labeled by parent study and ARC-520 dose. The record does not provide comparative testing, exposure-adjusted rates, event timing, or further detail on observation windows. Deaths are not reported in the listed group summaries. These limits restrict safety interpretation to the counts reported rather than supporting conclusions about comparative risk.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Extension Study of the Safety and Efficacy of Multi-dose Intravenous ARC-520 in Patients With Chronic Hepatitis B (HBV) Infection — NCT02738008.
- Registry record last updated 2026-01-13; status last verified 2025-12.
- Results first posted 2019-04-16.
- 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.
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18. Record Summary
The registry record describes a Phase 2, multicenter, single-group, open-label extension study of multi-dose intravenous ARC-520 with entecavir or tenofovir in people with chronic hepatitis B. It lists an enrollment of 12 and a terminated status.
The primary endpoint was the percentage of initial responders achieving a 1-log reduction in HBsAg at Week 36 compared with baseline. Initial responders were defined by an earlier reduction in serum HBsAg in the parent Heparc-2002 or Heparc-2003 study. The registry states that termination occurred before any participant reached Week 36, so the primary endpoint could not be analyzed.
The record lists descriptive safety counts for groups labeled by parent study and ARC-520 dose. It reports no analyses for the primary endpoint and no overall analyses. The design and missing Week 36 assessment leave the record without a comparative estimate of the planned biomarker response.