A Single- and Multiple-Dose Study of the Pharmacokinetics of TAK-491 in Healthy Chinese Participants: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Single- and Multiple-Dose Study of the Pharmacokinetics of TAK-491 in Healthy Chinese Participants (NCT02541669), a randomized phase 1 study. The primary outcome is Cmax: Maximum Observed Plasma Concentration for TAK-536 (the Active Moiety Derived From TAK-491) on Day 1.

2. Clinical Question

The study examined how TAK-491 exposure, measured through plasma concentrations of TAK-536, varied across the dose and treatment groups in healthy Chinese participants. It also recorded safety outcomes during the study. The registry identifies the work as a Phase 1 study and describes its purpose as assessing pharmacokinetics and safety after single and multiple doses.

This is a pharmacokinetic question, not a test of clinical benefit. The endpoint summarizes drug-related concentration in plasma over the stated sampling period. Results are reported separately for open-label and double-blind groups, so they should be read as arm-level descriptions rather than as a single overall estimate or a direct treatment-effect estimate. The registry record does not report a formal statistical comparison among these groups.

3. Trial Design

The registry describes a randomized, parallel-group Phase 1 study with an overall masking designation of quadruple. The official title also describes both open-label and double-blind treatment groups. These labels indicate that the study included more than one treatment-masking arrangement; the registry record does not explain which roles were masked or how masking was implemented across the different groups.

The listed enrollment is 64, and the study status is completed. The record gives a start date of 2015-11-20 and a primary completion date of 2017-03-17. It describes the participants as healthy Chinese subjects, rather than people being treated for a disease. The sponsor is Takeda.

There were open-label groups receiving TAK-491 40 mg or 80 mg and double-blind groups receiving TAK-491 40 mg or 80 mg. In the double-blind groups, participants also received a placebo-matching tablet corresponding to the other dose. A double-blind placebo group received placebo-matching tablets for both dose levels. Dosing was oral and once daily on Day 1 and Days 4 to 10, as described in the arm records.

The primary endpoint was measured on Day 1, with predose sampling and multiple post-dose time points up to 72 hours. The primary outcome record reports group geometric means and geometric coefficients of variation for the active-treatment arms. Arm sizes in those outcome records are 8 for each open-label group and 16 for each double-blind active-treatment group. The registry record does not report a statistical analysis comparing dose levels or masking formats, or a placebo result for the primary endpoint. Therefore, the study design and posted endpoint values support a descriptive account of measured concentrations, but not a claim about statistical significance between groups.

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: Healthy Chinese participants were enrolled in the study in 2-parts, Open-label in which participants were allocated equally and randomly to TAK-491 40 milligram (mg) and TAK-491 80 mg and Double-blind in which participants were allocated equally and randomly to 1 of 3 regimens Placebo, TAK-491 40 mg, and TAK-491 80 mg.

Open Label Treatment Period

Double-Blinded Treatment Period

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The pharmacokinetic (PK) set consisted of all participants who received study drug and had at least 1 measurable plasma concentration for TAK-536.

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.

Population: The randomized set included all participants who were randomized.

6. Primary Endpoint

The registry lists the primary outcome as Cmax: Maximum Observed Plasma Concentration for TAK-536 (the Active Moiety Derived From TAK-491) on Day 1, measured over Day 1 pre-dose and at multiple time points (up to 72 hours) post-dose.

The primary endpoint is Cmax, defined as the maximum observed plasma concentration of TAK-536, the active moiety derived from TAK-491. It is reported in nanograms per milliliter (ng/mL) for Day 1, using predose and multiple post-dose measurements collected up to 72 hours after dosing.

Cmax is a pharmacokinetic measure of the highest observed concentration during the specified sampling window. It is used to describe the concentration profile following administration, rather than to measure a clinical outcome such as symptom change or disease control. A higher group geometric mean indicates a higher typical concentration on the scale used for the endpoint; it does not, by itself, establish a clinical effect.

The registry reports the endpoint as a geometric mean and gives a geometric coefficient of variation as its dispersion measure. A geometric mean is useful when concentration measurements are positive and vary multiplicatively, so that relative rather than absolute variation is relevant. The geometric coefficient of variation describes spread on that multiplicative scale. It is not a confidence interval and does not show the precision of the group estimate in the same way a confidence interval would.

The endpoint is defined for a pharmacokinetic analysis set: participants had to receive study drug and have at least 1 measurable plasma concentration for TAK-536. The registry record does not report the number excluded from this set, the handling of concentrations below quantification limits, or confidence intervals for the group estimates.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The principal endpoint is a continuous pharmacokinetic measure: maximum observed plasma concentration of TAK-536 on Day 1. Concentration measurements were collected before dosing and at multiple times after dosing, up to 72 hours. For each active-treatment group, the registry reports a geometric mean and geometric coefficient of variation. It does not report individual-level values or a confidence interval for any group estimate.

Why use a geometric mean?

In general, concentration data are positive and may vary in proportional rather than additive ways. A geometric mean summarizes the central level after accounting for this multiplicative pattern, then expresses the result on the original measurement scale. It can be a suitable summary when a small number of relatively high values would otherwise pull an arithmetic mean upward. The geometric mean does not describe every participant's value, and it should not be read as a median unless that is explicitly stated. The registry identifies the measure as a geometric mean, not a median.

What does the coefficient of variation describe?

The geometric coefficient of variation is a measure of relative spread in concentration values. In general, a coefficient of variation relates variability to the scale of the measurement, making it more useful than an absolute spread measure when variation tends to grow with the level of the outcome. The listed coefficients describe within-group variation on a multiplicative scale. They do not quantify uncertainty about the mean, and they are not confidence limits. A confidence interval would require a separate estimate of precision and is not reported in the registry record.

What can be inferred from arm summaries?

Arm summaries permit descriptive comparisons: readers can see the reported Cmax geometric means and coefficients of variation for the open-label and double-blind active-treatment groups. In general, a formal comparison requires an analysis that accounts for sampling variability and specifies the estimand, model, and comparison of interest. The registry record reports no analyses for the primary outcome, and no inferential comparison between dose groups or treatment formats. The observed differences in group summaries should therefore not be described as statistically significant or as evidence that one group differs from another beyond chance.

The record calls the trial randomized and parallel, but it does not describe the randomization method, allocation concealment, or the statistical model used for the endpoint. It also does not report whether the endpoint was analyzed after a transformation, how outlying observations were handled, or whether covariates were included. Those details are not reported in the registry record, so no specific analysis procedure should be assumed.

How should the sample-size illustrations be read?

In general, sample-size planning calculations describe the number of participants that might be needed under stated assumptions to detect a target effect with a chosen level of power. They are planning illustrations, not estimates of the probability that the completed trial found an effect. The registry's stated illustration assumptions use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. For non-time-to-event outcomes, the convention is participants per arm. The posted information does not establish that these assumptions were used to design this trial, and the registry record does not report the trial's own sample-size justification. Because the endpoint is not reduced to one comparison, no single two-arm planning result should be treated as the study's definitive sample-size analysis.

There are 7 outcome measures listed, but the registry record reports no secondary results. The absence of posted inferential analyses also means no multiplicity adjustment can be evaluated. In general, when several outcomes or comparisons are tested, the chance of at least one false-positive result can increase unless the analysis plan addresses multiplicity. That is a general statistical consideration, not evidence that a particular procedure was or was not used in this study. The procedure is not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 7 outcome measures and reports no secondary results. It also reports no analyses for the primary outcome. No multiplicity procedure, hierarchy of endpoints, or prespecified testing sequence is described in the registry record. Consequently, it is not possible to determine how the study would have controlled the chance of false-positive findings across multiple outcomes or comparisons. This is a limitation of what is documented, not evidence that no statistical plan existed.

Missing-data procedures are not reported in the registry record. The primary pharmacokinetic population is defined as participants who received study drug and had at least 1 measurable plasma concentration for TAK-536. The record does not state how many otherwise enrolled participants were not included in that set, whether any scheduled concentrations were missing, or how missing measurements were handled. It also does not report rules for values below a quantification threshold or the handling of protocol deviations.

The posted arm counts describe participants contributing to the primary endpoint results, but the record does not explain whether these are all randomized participants, all treated participants, or only those meeting the pharmacokinetic population definition. The eligibility definition for the pharmacokinetic set is reported; the relationship between that set and other possible analysis populations is not.

Interim analyses and stopping rules are not reported in the registry record. Neither is a detailed statistical analysis plan. Without those details, readers cannot assess whether outcome selection, exclusions, or analysis choices were prespecified. No adjusted analyses or confidence intervals are posted, so the precision and robustness of the descriptive group summaries cannot be assessed through those methods.

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 lists no serious adverse events in the groups shown. The open-label TAK-491 40 mg group had 0 serious events among 8 at risk, and the open-label TAK-491 80 mg group had 0 among 8. The double-blind placebo group had 0 among 16; the double-blind TAK-491 40 mg group had 0 among 16; and the double-blind TAK-491 80 mg group had 0 among 16. The registry also records 0 deaths in each group.

These serious-event counts are distinct from the counts for other adverse events. Other adverse events were recorded for 4 participants in each open-label active-treatment group, 6 in the double-blind placebo group, 4 in the double-blind TAK-491 40 mg group, and 10 in the double-blind TAK-491 80 mg group. The registry record does not provide event-term details in the serious-event listing.

Zero recorded serious events in a group does not establish that the risk is absent. These are descriptive observations in the listed groups, and the registry record does not report a comparative statistical analysis or confidence intervals for safety outcomes. The counts should not be interpreted as proof of equivalence between groups or as a complete account of all possible risks.

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

The posted results describe Day 1 plasma exposure to TAK-536 following TAK-491 dosing in healthy Chinese participants. The outcome is a maximum observed concentration, summarized by a geometric mean, with a geometric coefficient of variation describing relative dispersion. The geometric means are higher in the 80 mg arms than in the 40 mg arms within both the open-label and double-blind formats. This is a description of the reported arm summaries, not a formal conclusion about a dose effect.

No p-values, confidence intervals, or statistical comparisons are reported for the primary endpoint. The precision of the group estimates and the statistical evidence for differences between groups therefore cannot be determined from the registry record. Differences in the posted values may reflect real differences, sampling variability, or both; the record does not provide an inferential analysis to distinguish these possibilities.

The results also do not establish that the observed concentrations produce a clinical benefit. Participants were healthy, and the primary endpoint was pharmacokinetic rather than a disease or patient-centered outcome. The registry record does not report clinical efficacy outcomes. It does not establish how these concentration summaries relate to outcomes in people with a health condition.

The results are specific to the reported sampling window and Day 1 endpoint. The study also included dosing on Days 4 to 10, but the primary values are not results from that multiple-dose period. They should not be generalized to steady-state exposure or to other dosing schedules. The record does not provide the multiple-dose endpoint values in the primary result described.

Safety reporting shows no serious adverse events or deaths in the listed groups, while other adverse events were recorded. The absence of serious events in these groups is not evidence that serious events cannot occur, and the registry does not provide comparative safety estimates. Overall, the record gives descriptive pharmacokinetic and safety information for the study groups. It does not, on its own, establish treatment effectiveness, statistical equivalence, or the broader safety profile of TAK-491.

13. Why This Trial Matters Statistically

This study illustrates how pharmacokinetic results differ from clinical outcome results. Cmax is a concentration endpoint that describes exposure after dosing. Reporting its geometric mean alongside a measure of relative spread helps convey both the typical concentration and how much measured concentrations varied within each arm. Such summaries are useful for describing drug exposure, but they are not substitutes for an analysis of clinical benefit or harm.

The registry also makes clear why arm-level numbers need careful interpretation. Results are separated by dose and by open-label or double-blind format, and the record does not report a single inferential comparison. A reader can describe the observed pattern across arms, but cannot infer statistical significance from the means alone. This distinction is central to biostatistical reading: descriptive differences and tested effects answer different questions.

The study's endpoint definition and analysis population also matter. The pharmacokinetic set required receipt of study drug and at least 1 measurable TAK-536 concentration. This population is relevant to concentration summaries, while the record does not fully describe how it relates to other analysis populations. Clear population definitions help readers understand which participants contribute to an estimate and how applicable it may be.

Finally, the registry record demonstrates the limits of public summary reporting. It provides treatment-group estimates and adverse-event counts, but not confidence intervals, formal comparisons, detailed missing-data procedures, or a statistical analysis plan. These omissions do not show that analyses were not conducted; they mean that readers cannot evaluate those aspects from the registry record. The most defensible interpretation is therefore precise and bounded: the posted values describe measured exposure and recorded events in this Phase 1 study, while inferential and clinical conclusions remain unreported.

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.

This trial was conducted in healthy Chinese participants, so the record does not directly describe pharmacokinetics or safety in people being treated for a medical condition. The primary endpoint is a concentration measure rather than a clinical outcome, and the registry does not report efficacy results. The findings are also tied to the described dosing schedule and Day 1 sampling window; the primary values do not represent the multiple-dose period.

The posted Cmax summaries are limited to geometric means and geometric coefficients of variation. Confidence intervals, p-values, and formal comparisons are not reported in the registry record. As a result, the precision of the estimates and the statistical evidence for differences among dose or treatment-format groups cannot be assessed from these summaries.

The active-treatment groups are reported separately as open-label and double-blind groups, and the record gives no formal analysis comparing these formats. Although the study is described as randomized, the randomization procedures and allocation concealment are not reported. The overall quadruple masking designation appears alongside explicit open-label and double-blind arm descriptions, but the roles covered by the masking designation are not specified in the registry record.

The record does not report detailed missing-data handling, the number excluded from the pharmacokinetic set, the treatment of below-quantification measurements, interim analyses, or the statistical analysis plan. It also does not provide the primary endpoint value for the placebo group. Safety counts are descriptive and lack comparative estimates or uncertainty measures. These reporting gaps limit assessment of statistical robustness and generalizability.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Single- and Multiple-Dose Study of the Pharmacokinetics of TAK-491 in Healthy Chinese Participants — NCT02541669.
• Registry record last updated 2020-02-05; status last verified 2020-01.
• Results first posted 2020-02-05.
• 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

NCT02541669 is a completed, randomized, parallel-group Phase 1 study sponsored by Takeda. It enrolled 64 healthy Chinese participants and assessed pharmacokinetics and safety for TAK-491. The registry gives a start date of 2015-11-20 and a primary completion date of 2017-03-17.

The primary endpoint was Day 1 Cmax for TAK-536, the active moiety derived from TAK-491, measured in ng/mL. Results are reported as geometric means and geometric coefficients of variation for open-label and double-blind active-treatment groups. The record does not report inferential analyses or a placebo result for this primary endpoint.

No serious adverse events or deaths are listed in the reported groups; other adverse events are recorded. Secondary results, confidence intervals, detailed missing-data procedures, and the statistical analysis plan are not reported in the registry record.