Safety and Efficacy of MP-424 to Treat Chronic Hepatitis C: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy of MP-424 to Treat Chronic Hepatitis C (NCT00621296), a na phase 2 study. The primary outcome is Undetectable HCV RNA at 24 Weeks After Completion of Drug Administration.

2. Clinical Question

The clinical question is about an observed virologic outcome after treatment, rather than a comparison between assigned treatments. The endpoint is listed as a number of participants, so its natural interpretation is a count of participants meeting the undetectable HCV RNA criterion at the specified follow-up. The registry record does not report that count, the proportion meeting the criterion, or an estimate of uncertainty around the outcome. Therefore, the clinical question can be described from the record, but its primary efficacy result cannot be answered from the posted results.

The study concerns patients with chronic hepatitis C, and the official title identifies genotype 1b. No further eligibility details or description of the endpoint threshold are reported in the registry record. The question is also bounded by the stated follow-up: it concerns assessment at 24 weeks after the last dose, not a broader claim about outcomes at other times. With no concurrent comparator, any observed count would describe participants in this study; by itself, it would not establish how outcomes differ from those under another treatment or under no treatment.

3. Trial Design

This is a Phase II study of MP-424 in patients with genotype 1b hepatitis C. The registry record lists a single-group model, enrollment of 15, and no masking. Allocation is listed as NA. The only intervention listed is MP-424 (telaprevir), and no comparator intervention or control group is described. The sponsor is Tanabe Pharma Corporation. The record lists the study start as 2008-01, primary completion as 2009-02, and status as completed.

The brief description says the purpose was to assess efficacy and safety after administration of MP-424 to patients with chronic hepatitis C. The dosing period is described as 24 Weeks. The primary endpoint timeframe refers to measurement 24 weeks after completion of drug administration or drug withdrawal, and says that subjects were assessed 24 weeks following the last dose. The record does not give further details about treatment administration, permitted concomitant treatments, eligibility criteria, or study conduct.

The single-group structure matters when interpreting efficacy. Without a concurrent comparator, the study can describe outcomes among enrolled participants, but it does not directly estimate a between-group treatment contrast. The record does not describe random assignment, and allocation is listed as NA; it would be inappropriate to characterize the study as randomized. Likewise, masking is listed as none, so the record does not support describing outcome assessment as blinded.

The registry record does not report a sample-size justification, a target enrollment rationale, or a detailed statistical analysis plan. The fact that enrollment was 15 is descriptive; it does not reveal whether the study met a prespecified target or whether a particular precision or power goal was intended. The posted record also does not explain why a single-group design was selected or how treatment effects were intended to be judged.

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:

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 Undetectable HCV RNA at 24 Weeks After Completion of Drug Administration, measured over 24 Weeks After Completion of Drug Administration (dosing period is 24 Weeks) or drug withdrawal. The subjects were assessed at 24 weeks following the last dose of study drug..

The primary endpoint is titled “Undetectable HCV RNA at 24 Weeks After Completion of Drug Administration.” It is recorded as a number of participants, with the assessment described as occurring 24 weeks following the last dose. The dosing period is listed as 24 Weeks, and the timeframe also refers to drug withdrawal. The registry record does not provide a more detailed definition of undetectable, a laboratory threshold, or the endpoint’s analysis population.

In general, an endpoint based on HCV RNA asks whether the virus is detectable in a participant’s measurement at the specified time. A count endpoint records how many participants meet the stated criterion; it is not, by itself, a comparison between treatments. A fixed follow-up point gives the outcome a defined time reference, which is important because measurements taken at different times can answer different questions. The endpoint concerns the stated post-treatment assessment, not all later outcomes or the durability of a response beyond that assessment.

In general, virologic measures are used to describe whether viral material is detected after treatment. The clinical meaning of a particular threshold depends on how the test and criterion are defined. Those details are not reported in the registry record, so the endpoint title alone does not establish the assay threshold or any additional clinical interpretation. Most importantly, the registry record does not report the number of participants who met the endpoint. The endpoint’s definition and timing are available, but its observed result is not.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of outcome is recorded?

The primary endpoint is a binary participant-level outcome: a participant either meets the criterion of undetectable HCV RNA at the specified assessment or does not. The registry record lists the measure as a number of participants, rather than a continuous laboratory value. In general, a binary outcome can be summarized by the number meeting the criterion and, if the number assessed is known, by the corresponding proportion. The registry record does not report the primary endpoint count or the number assessed, so neither summary can be recovered from the entry.

Counts and proportions answer related but distinct questions. A count states how many participants had the outcome; a proportion relates that count to a defined denominator. The denominator should reflect the analysis population and the handling of participants without an observed measurement. Those details matter particularly when some participants do not complete follow-up. In this record, the endpoint population and missing-data handling are not reported, so the meaning of a potential denominator cannot be specified.

What does uncertainty mean?

General statistical explanation: an estimate from a study is subject to sampling variability. A confidence interval describes uncertainty around an estimate under a stated statistical procedure and its assumptions. It is not a guarantee that the true value lies within the interval, nor does it correct for limitations in design, missing observations, or measurement. For a binary endpoint, the interval’s width depends on the observed outcome and the amount of information available. Since the primary result and its analysis are not reported in the registry record, there is no interval to interpret.

A p-value, when reported, evaluates how compatible observed data are with a specified null hypothesis under the test assumptions. It does not measure the size or clinical importance of an effect. A p-value also cannot substitute for a confidence interval or for the outcome itself. No primary endpoint p-value or statistical test is reported in the registry record, and none should be inferred from the study’s phase, enrollment, or design.

Why does the single-group design matter?

General statistical explanation: a concurrent comparison group can help distinguish changes associated with an intervention from changes that could also occur over time or for other reasons. In a single-group study, outcomes can be described among those enrolled, but there is no within-study comparator for estimating a treatment contrast. The registry record identifies a single-group model and no comparator. Therefore, even if the primary count were available, it would be a description of this group’s outcome, not a randomized comparison of treatment strategies.

Allocation is listed as NA and masking as none. These entries do not support assumptions about randomization or blinded assessment. The record does not explain whether outcome assessment used any procedures intended to limit measurement bias. Such design information can be relevant to how results are interpreted, but it is not available in the registry record.

How should planning illustrations be understood?

General statistical explanation: sample-size planning asks how many participants may be needed to detect a defined effect with a chosen error rate and power under stated assumptions. A planning calculation is not evidence that an effect was observed, and it is not “observed power.” If a calculation is based on an effect estimated from a study, that estimate is uncertain; treating it as fixed can make the resulting planning illustration optimistic or otherwise sensitive to the assumed effect.

The record describes planning illustrations as using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect set as a stated fraction of the observed effect. It also distinguishes participant-per-arm calculations from total event calculations for time-to-event outcomes. These are planning assumptions, not a description of the single-group study’s actual allocation or a reported sample-size justification. The trial itself is recorded as single group, and no sample-size justification is reported in the registry record. Any such planning illustration should therefore be read as hypothetical rather than as the study’s design or an outcome of its analysis.

What role could over-dispersion play?

General statistical explanation: over-dispersion arises when observed variability is greater than a model assumes. For count outcomes, a model that assumes less variability than is present can produce uncertainty estimates that are too small. Model choice and diagnostic assessment depend on the outcome structure and data. The primary endpoint in this record is a participant count for a binary criterion, and the registry record does not describe a model-based analysis or an over-dispersion assessment. There is no basis for saying that over-dispersion was present or that a particular correction was used.

What can be concluded from the posted analysis record?

The registry record lists one outcome measure and no analysis entries. This means that the endpoint definition is available, but a result and its statistical treatment are not reported there. The absence of an analysis entry does not establish what analyses may have been conducted elsewhere; it means only that they are not reported in the registry record. No adjustment method, confidence-interval method, hypothesis test, or prespecified analysis population can be identified from the record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("MP-424")
n      <- c(15)
events <- c(1)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  MP-424  15  1  6.7  0.2  31.9  1.2  29.8  1.6  30.2

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one primary outcome measure, titled around undetectable HCV RNA at the stated post-treatment assessment. It lists no analysis entries. The record does not report whether additional efficacy outcomes were assessed outside the registry entry, whether any multiplicity procedure was planned, or how the primary endpoint was designated in a statistical analysis plan. No adjustment for multiple testing should be assumed.

Multiplicity arises in general when several hypotheses or outcomes are tested: the chance of at least one apparently unusual result can increase as the number of tests increases. Procedures to address this depend on the analysis plan and the family of hypotheses being considered. Since a multiplicity plan is not reported in the registry record, it is not possible to determine what approach, if any, was used. The single listed endpoint does not establish that no other analyses were conducted.

Missing-data handling is also not reported. The registry record does not state how participants without an endpoint assessment were treated, whether all enrolled participants were included in the primary analysis, or how withdrawal affected endpoint classification. Although the timeframe refers to assessment after the last dose or drug withdrawal, it does not specify how unavailable measurements were handled. The number enrolled cannot be treated as the number assessed for the endpoint without a reported analysis population.

The record does not identify an intention-to-treat, per-protocol, or other analysis population. It also does not provide a flow of participants through treatment and follow-up. These omissions leave uncertainty about the denominator and the consequences of missing observations. They do not permit a conclusion that data were complete or that a particular missing-data method was applied.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: herpes zoster (6.7%).

The registry record lists 15 participants at risk for serious adverse events and 1 participant affected. For other adverse events, it lists 15 at risk and 14 affected. These are participant counts in the single MP-424 group. They are safety descriptions, not comparisons with an untreated or active control group. The record does not report a death count; deaths are not reported in the registry record.

Herpes zoster is listed among the top serious adverse event terms, at 6.7%. This term-level listing should be read as the registry presents it. The record does not provide further detail about event timing, severity beyond its serious-event classification, clinical course, or whether the event was judged related to MP-424. Nor does it describe the method used to collect or code adverse events.

In general, “at risk” identifies the group counted as eligible to experience or report an event in the safety summary. A participant count is not necessarily the same as an event count if one participant can experience more than one event; the record’s figures are specifically presented as participants affected. The listed counts alone do not establish causation, comparative risk, or the likelihood of an event in another population. The registry record does not report enough detail to make those broader assessments.

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

The record establishes that a Phase II, single-group study of MP-424 (telaprevir) enrolled 15 patients with chronic hepatitis C and defined a primary endpoint based on undetectable HCV RNA at 24 weeks after completion of drug administration or drug withdrawal. It also reports a 24 Weeks dosing period and assessment 24 weeks following the last dose. These details describe the study question and timing, not the observed efficacy result.

The primary endpoint count is not reported in the registry record. Therefore, it is not possible to state how many participants met the endpoint, what proportion did so, or how precise an estimate would be. The absence of a result is not evidence that the outcome was favorable, unfavorable, or unchanged. The record also does not report an endpoint confidence interval, a statistical test, or an efficacy analysis population.

Even if an observed endpoint count were available, the single-group design would limit interpretation. It could describe the outcome among participants studied, but without a concurrent comparator it would not directly show how outcomes differed under another treatment or no treatment. The registry record does not report random allocation or masking, and it does not supply the details needed to assess potential sources of bias or the role of missing observations.

The safety entries report 1 participant with a serious adverse event and 14 participants with other adverse events, each among 15 at risk. Herpes zoster is listed at 6.7% among the top serious adverse event terms. These entries are descriptive and do not, on their own, establish that MP-424 caused an event or permit comparison with another group. Deaths are not reported in the registry record.

In general, a study result should be interpreted using its estimate, uncertainty, design, and analysis population together. Here, the design and endpoint are described, but the primary estimate and analysis details are absent. Accordingly, the available record supports a description of what was asked and some reported safety counts, but not an efficacy conclusion or a comparative assessment of safety.

14. Why This Trial Matters Statistically

This study is statistically notable for the distinction between defining an endpoint and reporting its result. The registry record gives a specific binary primary endpoint and its follow-up timing, yet does not report the number of participants who met it. Without that count, the primary efficacy question remains unanswered by the posted results. A clear endpoint definition cannot substitute for an observed estimate.

The single-group design also shapes what the study can establish. It can describe outcomes in the enrolled group, but it does not provide a concurrent contrast. This distinction is central when moving from a participant outcome to a claim about treatment effects. A single-group outcome may be informative descriptively, but a causal or comparative interpretation requires evidence beyond the outcome count alone.

Enrollment of 15 is a further reminder that the number enrolled and the amount of information available for a specific endpoint are not interchangeable. The record does not state how many participants had an endpoint assessment or how missing measurements were handled. Precision cannot be judged from enrollment alone, and no confidence interval is reported.

The registry also describes planning illustrations using hypothetical assumptions, including equal allocation between two arms, while the trial design is recorded as single group. Keeping planning calculations separate from the actual study design prevents a hypothetical calculation from being mistaken for the trial’s own sample-size rationale or for observed power. The registry record does not report that rationale.

Finally, the safety counts are presented without a comparator or detailed event context. They can be read as descriptive counts within the study group, but not as comparative risk estimates or proof of causation. Taken together, these features make the record useful for understanding the study structure and the information gap in the primary result, while limiting statistical conclusions about efficacy and comparative safety.

15. 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 result is not reported in the registry record. The endpoint is defined, but no participant count meeting the criterion, denominator for the analysis, proportion, confidence interval, or test result is available. The primary efficacy finding therefore cannot be evaluated from this record.

The study is listed as single group, with allocation NA and masking none. No concurrent comparator is reported, so the design does not provide a within-study treatment contrast. The registry record also does not describe randomization, blinded outcome assessment, or the procedures used to measure HCV RNA. These details should not be inferred from the study title or endpoint.

Enrollment is listed as 15, but the record does not report the number completing treatment, the number assessed at the endpoint, or participant disposition. It does not describe missing-data handling or identify an analysis population. As a result, the relationship between enrollment and the denominator for any endpoint analysis is unknown.

The record does not provide a sample-size justification, a detailed analysis plan, or a multiplicity strategy. It does not explain whether other outcomes or analyses were considered, nor does it report the statistical methods used for the primary endpoint. The planning assumptions described in the registry should not be treated as the study’s actual design rationale.

Safety information is limited to participant counts and a top serious adverse event term. The record does not report detailed event narratives, timing, relatedness assessments, or a death count. These limitations prevent broader conclusions about event patterns or comparative safety. They also do not establish that unreported details were absent; they are not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety and Efficacy of MP-424 to Treat Chronic Hepatitis C — NCT00621296.
• Registry record last updated 2026-01-06; status last verified 2025-12.
• Results first posted 2012-10-19.
• 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.

19. Record Summary

The registry record describes a completed Phase II, single-group study of MP-424 (telaprevir) in patients with chronic hepatitis C; the official title specifies genotype 1b. Enrollment was 15. Allocation is listed as NA and masking as none. The study start is recorded as 2008-01 and primary completion as 2009-02.

The primary endpoint was the number of participants with undetectable HCV RNA at 24 weeks after completion of drug administration or drug withdrawal. The dosing period was 24 Weeks, with assessment 24 weeks following the last dose. The observed endpoint result and analysis are not reported in the registry record.

Safety entries list 1 participant with a serious adverse event among 15 at risk and 14 participants with other adverse events among 15 at risk. Herpes zoster is listed among the top serious adverse event terms at 6.7%. A death count, detailed analysis plan, missing-data approach, and sample-size justification are not reported in the registry record.