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 An Open-label Safety Study of Lusutrombopag (S-888711) in Adults With Chronic Immune Thrombocytopenia (ITP) (NCT01129024), a na phase 2 study. The primary outcome is Number of Participants With Adverse Events.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01129024 |
| Phase | Phase 2 |
| Condition | Immune Thrombocytopenia |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 19 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Shionogi |
| Results posted | Yes |
2. Clinical Question
Population
Adults with relapsed persistent or chronic immune thrombocytopenia, with or without prior splenectomy, were eligible for the study. The primary outcome population is described as all enrolled and treated participants. The registry records an enrollment of 19.
Intervention
Participants received oral lusutrombopag, starting at 0.5 mg once a day. Treatment could continue for up to 3 years or until study termination, with dose adjustment based on platelet counts. The registry describes a possible increase when the platelet count remained < 50,000/μL, up to a maximum dose of 2.0 mg.
Comparator
No comparator group is listed. The study is recorded as single-group, with allocation marked NA and masking marked NONE. Its safety results therefore describe participants receiving lusutrombopag, rather than a randomized contrast between treatments.
Primary question
The primary outcome asks how many participants experienced adverse events during the stated safety observation period. The registry defines adverse events broadly, including untoward medical occurrences whether or not they were considered related to the investigational product. The question is descriptive: what adverse events were recorded among treated participants?
The registry identifies the study as a phase 2, open-label safety study of lusutrombopag in adults with immune thrombocytopenia. Its stated primary objective was to assess long-term safety in adults with relapsed persistent or chronic disease, including participants with or without prior splenectomy. The title and official title both identify a safety focus, rather than a comparative efficacy question.
Secondary outcomes listed include duration of response, bleeding severity, platelet-count categories, platelet-count categories without rescue medication, and change in platelet counts at the final visit. Those outcomes broaden the clinical description, but they do not create a control group or establish a causal treatment comparison. Results for those outcomes are not detailed in the registry record for this analysis.
3. Trial Design
This is a phase 2, open-label, single-group study of lusutrombopag. The registry lists no masking and marks allocation as NA. These design details mean that participants and study personnel were not masked to treatment, and the record does not describe assignment to competing treatment groups. The study is not a randomized comparison.
The registry records enrollment of 19 participants and identifies the primary outcome population as all enrolled and treated participants. Lusutrombopag was administered orally once a day, beginning at 0.5 mg. The dose was adjusted based on platelet counts. The protocol description allows an increase of 0.25 mg if a participant’s platelet count remained < 50,000/μL, with a maximum dose of 2.0 mg. Treatment was intended to continue for up to 3 years or until study termination.
The primary safety observation period runs from the first dose in the extension study through 6 weeks after the last dose. The registry also reports a median time on study treatment of 148 days, with a range of 10-387 days. These summaries describe treatment exposure in the observed study, which is distinct from the stated maximum treatment duration.
The study status is recorded as TERMINATED. The start date is 2010-04-29 and the primary completion date is 2011-06-30. The reason for termination is not reported in the registry record. The record also does not report a planned sample-size justification, a detailed statistical analysis plan, or interim analyses. Without those details, the study’s design rationale and any planned decision rules cannot be reconstructed from the registry information.
Because the study is single-group and open-label, its observed event counts can describe what was recorded during exposure and follow-up. They do not, by themselves, estimate how event frequency would compare with another treatment or with no study treatment. This design is aligned with a descriptive safety question but has limited capacity for separating treatment effects from other explanations for events.
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
| Stage | Lusutrombopag |
|---|---|
| STARTED | 19 |
| COMPLETED | 0 |
| NOT COMPLETED | 19 |
Reasons for not completing this period:
| Reason | Lusutrombopag |
|---|---|
| Physician Decision | 5 |
| Study Terminated by Sponsor | 8 |
| Withdrawal by Subject | 2 |
| Lack of Efficacy | 3 |
| Needed a Platelet Transfusion | 1 |
Analysis population for the primary outcome, as defined in the registry: All enrolled and treated participants
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: All enrolled and treated participants
| Characteristic | Unit | Lusutrombopag |
|---|---|---|
| Participants analysed | 19 | |
| Age, Continuous | years | 54.7 (SD 20.98) |
| Sex: Female, Male: Female | Participants | 11 |
| Sex: Female, Male: Male | Participants | 8 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 2 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 17 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race/Ethnicity, Customized: White | Participants | 18 |
| Race/Ethnicity, Customized: Black or African American | Participants | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Adverse Events, measured over From first dose of study drug in the extension study up to 6 weeks after last dose; median (range) time on study treatment was 148 (10-387) days..
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of participants with adverse events. It is a participant count, not a rate of events per unit of time and not a measure of event severity alone. The registry defines an adverse event as an untoward medical occurrence in a participant given a pharmaceutical product during a clinical investigation. An event can qualify whether or not it is thought to be related to the investigational product. Events reported after initial study-drug administration are considered treatment-emergent.
The record separately defines serious adverse events by outcomes or clinical importance, including death, a life-threatening event, hospitalization or prolonged hospitalization, persistent or significant disability, congenital anomaly or birth defect, or another important medical event judged to require intervention or to jeopardize the participant. It also defines a treatment-related adverse event as one the investigator considers possibly, probably, or definitely related to study drug. These categories are not interchangeable: an event can be adverse without being serious, and seriousness does not itself establish that the event was caused by treatment.
A participant-count endpoint is useful for describing how many people experienced an event during the specified observation period. It gives a direct summary of the number affected in this treated group. It does not show how often events recurred in the same participant, and it does not express exposure-adjusted risk. Because there is no comparator group, the count also cannot establish whether the observed frequency differs from what would have occurred under another treatment.
The endpoint’s interpretation depends on the time period and population used. The registry specifies observation from the first extension-study dose to 6 weeks after the last dose, and defines the population as all enrolled and treated participants. The registry’s primary endpoint title is broad; details about specific non-serious event categories or a treatment-related count are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary safety results describe adverse events among participants treated with lusutrombopag in a single-group, open-label study. The registry records 19 participants at risk in the lusutrombopag group and 19 participants affected in the other-adverse-event count. It records 1 participant with a serious adverse event and 0 deaths. These are descriptive counts from the study population, not comparative estimates.
The serious-event terms listed are thrombocytopenia, overdose, and suicidal ideation, each reported at 5.3%. These terms describe events recorded in the registry; the listing alone does not establish that each event was caused by lusutrombopag. The registry’s definition of a treatment-related adverse event depends on an investigator’s assessment, and the figures stated do not provide a treatment-related attribution for each event.
Precision is limited by the small recorded enrollment and the absence of a comparator group. In a study with few participants, a count may change substantially in meaning when only a small number of observations differ. The record does not provide confidence intervals for these event counts, so their statistical precision cannot be quantified from the information described. General statistical principle: a confidence interval expresses a range of values compatible with the observed data under a specified method; it is not a guarantee that the true value lies in that range.
Observation time also matters for safety interpretation. The primary timeframe extends from the first extension-study dose through 6 weeks after the last dose, while the reported median time on treatment was 148 days and the range was 10-387 days. Participants therefore had different recorded treatment durations. A simple participant count does not adjust for those differences in exposure time, and the registry entries do not include event rates per person-time.
The record states that the study was terminated, but the reason is not reported in the registry record. It also does not report enough detail to determine whether all outcomes were assessed in the same way throughout the study or whether missing observations affected the results. The data support a description of reported adverse events in the treated group over the stated follow-up. They do not establish a comparison with an untreated group, quantify a treatment effect, or resolve whether any event was attributable to the drug.
In particular, the absence of reported deaths in this record is a descriptive finding for the observed participants and follow-up. It should not be interpreted as evidence that the risk of death is absent. Likewise, the number with serious events does not by itself indicate the likelihood of serious events in a broader population. Both statements require attention to the limited size and duration of observation, as well as the lack of a concurrent comparison group.
9. Statistical Methods Explained
The registry describes a participant-count endpoint and posts event counts rather than an estimate from a comparative statistical model. No analysis results are listed in the registry record. The interpretation therefore centers on the reported counts, their definitions, and the study design. General statistical concepts can clarify what these summaries can and cannot show, but they do not replace an analysis plan that is not reported in the registry record.
What does a participant count summarize?
A count of participants with an event records whether each participant experienced an event during the defined observation period. It is different from a count of all event occurrences: repeated events in the same participant may still contribute only that participant to a participant-count summary. The primary outcome is worded as the number of participants with adverse events. The posted serious-event result is also a participant count. These summaries answer how many participants were recorded in the relevant category, not how many total episodes occurred.
Counts need a defined population and observation window. The registry identifies all enrolled and treated participants as the primary population and specifies a timeframe from the first dose of study drug in the extension study up to 6 weeks after the last dose. A count should be read in the context of those boundaries. It does not automatically describe everyone who might receive the drug outside this study, nor does it cover time beyond the recorded window.
Why is the study design important?
The record describes a single-group, open-label design. With no comparator group, the observed count cannot be set against a concurrently observed count under another intervention. The study can document events occurring among treated participants, but it cannot isolate the contribution of treatment from disease-related events, other exposures, or other explanations using a randomized contrast. Open-label knowledge of treatment can also affect event recognition or reporting; whether this occurred in this study is not reported in the registry record.
General statistical principle: a control group can help distinguish outcomes associated with treatment from outcomes that would also occur without that treatment, especially when assignment is randomized. This study’s registry design does not provide that comparison. Therefore, a difference from an external expectation or from a different study should not be treated as a randomized treatment effect.
What does precision mean for these counts?
A count is a direct description of the observed participants, but it is not a precise estimate of the frequency that would occur in a wider population. General statistical principle: precision describes how much the estimate would vary across repeated samples under a statistical model. Confidence intervals are one common way to express uncertainty around an estimate. No confidence interval for the adverse-event counts is stated in the registry record, so the degree of statistical uncertainty is not quantified in the posted results.
Small studies generally provide less information about uncommon outcomes than larger studies. This is a general principle, not a numerical estimate of uncertainty for this trial. The enrollment of 19 and the observed serious-event count of 1 make clear that the result is based on limited observations. It would be inappropriate to treat an unobserved event as proof that the event cannot occur, or to treat a recorded event count as a stable population rate.
How should treatment duration be considered?
The registry reports median treatment time of 148 days and a range of 10-387 days. Since observation durations varied, a participant count does not account for the amount of time each participant was exposed. General statistical principle: person-time rates can incorporate differing observation time, but they require suitable exposure-time and event data. Those rates are not stated in the registry record. The posted count should therefore be understood as a summary over the specified follow-up, not as an exposure-adjusted rate.
The treatment period was described as up to 3 years or until study termination, but the actual reported treatment-time summary is shorter and varies across participants. The planned maximum is not the same as each participant’s observed duration. It also does not demonstrate that every participant remained under observation for the maximum period.
What do the planning illustrations mean?
The registry’s sample-size assumptions describe planning illustrations computed from an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. For time-to-event illustrations, the total number of events is used; for other illustrations, the measure is participants per arm.
These are planning scenarios, not the study’s observed results and not evidence of observed power. The study itself is recorded as single-group, not as an equal-allocation comparison. Thus, assumptions about two-arm allocation in a planning illustration should not be confused with the design used for this lusutrombopag safety study. The registry does not report the study’s own sample-size justification or a statistical plan that would establish these illustrations as the original design basis.
General statistical principle: power is a design property calculated under specified assumptions about an outcome, effect, variability, and analysis. A post hoc calculation using the observed effect does not show that the study had a particular probability of detecting a real effect before data collection. In a safety study with no comparator, a two-arm effect-detection scenario is especially distinct from the descriptive event-count question actually represented by the primary endpoint.
How should multiple outcomes be viewed?
The registry lists a primary safety outcome and secondary outcomes involving response duration, bleeding severity, platelet-count categories, rescue medication, and change in platelet count. Multiple outcomes can provide a broader picture, but testing or interpreting many outcomes raises questions about chance findings and selective emphasis. The statistical plan for handling multiplicity is not reported in the registry record. Therefore, no adjustment method or hierarchy among secondary outcomes can be assumed.
Overall, the methods information supports a descriptive reading of the posted safety counts, with attention to population, event definitions, and follow-up. It does not support a reconstructed hypothesis test, adjusted effect estimate, or exposure-adjusted risk calculation.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 6 outcome measures, including the primary adverse-event count and secondary outcomes related to response, bleeding, platelet counts, rescue medication, and change from baseline. The presence of multiple outcomes makes it important to know which analyses were planned as primary, how secondary outcomes were to be interpreted, and whether any adjustment for multiple comparisons was intended. Those statistical details are not reported in the registry record.
No analyses are listed in the registry record. The registry entries available for this analysis include the primary safety counts but do not provide complete results for the secondary outcomes. It is therefore not possible to determine whether all prespecified outcomes were reported, whether the outcome definitions changed, or whether any analyses were omitted. The reason the study was terminated is also not reported in the registry record.
The primary population is described as all enrolled and treated participants. The registry does not report how missing observations were handled, whether participants who stopped treatment remained under follow-up, or whether any imputation procedure was used. It also does not provide a detailed accounting of participants who discontinued or their reasons for discontinuation. These gaps matter because incomplete follow-up can affect how many events are detected and how the observed group represents the population initially enrolled.
The results should consequently be read as posted descriptive counts, not as a complete account of every possible analysis or of the handling of missing data. No assumptions about imputation, multiplicity adjustment, interim monitoring, or analysis populations beyond the stated primary population are warranted from the registry record.
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 |
|---|---|---|---|
| Lusutrombopag | 1 | 19 | 5.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Lusutrombopag | 0 of 19 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Lusutrombopag | 19 of 19 |
Most frequent serious adverse event terms
| Event term | Organ system | Lusutrombopag |
|---|---|---|
| Thrombocytopenia | Blood and lymphatic system disorders | 1 of 19 |
| Overdose | Injury, poisoning and procedural complications | 1 of 19 |
| Suicidal ideation | Psychiatric disorders | 1 of 19 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Lusutrombopag |
|---|---|---|
| Nasopharyngitis | Infections and infestations | 8 of 19 |
| Fatigue | General disorders | 6 of 19 |
| Cough | Respiratory, thoracic and mediastinal disorders | 5 of 19 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 5 of 19 |
| Upper respiratory tract infection | Infections and infestations | 3 of 19 |
| Oropharyngeal pain | Respiratory, thoracic and mediastinal disorders | 3 of 19 |
| Nausea | Gastrointestinal disorders | 3 of 19 |
| Vomiting | Gastrointestinal disorders | 3 of 19 |
| Ecchymosis | Skin and subcutaneous tissue disorders | 3 of 19 |
| Contusion | Injury, poisoning and procedural complications | 3 of 19 |
Serious events with the highest arm-level rate: thrombocytopenia (5.3%), overdose (5.3%), suicidal ideation (5.3%).
The serious adverse-event summary records 1 participant with a serious event among 19 participants at risk in the lusutrombopag group. It records 0 deaths. The terms listed among the serious events are thrombocytopenia, overdose, and suicidal ideation, each reported at 5.3%. These are registry event descriptions and should not be read as proof of causation by the study drug.
Seriousness is a classification based on outcomes or clinical importance, not a judgment that an event was treatment-related. The registry defines treatment-related events separately, based on the investigator’s assessment. The listed terms alone do not say whether each was judged possibly, probably, or definitely related. That attribution is not reported alongside these figures.
The percentages are not additive measures of unique participants. Event terms can refer to overlapping records, and the registry entries do not specify enough detail to infer how terms relate to one another. The safest reading is to preserve each posted term and percentage as reported, without summing or interpreting them as separate risk estimates.
These counts apply to the study’s recorded participants and follow-up, with a median treatment time of 148 days and a range of 10-387 days. They do not estimate the rate in a broader population or compare risk against another treatment. The small single-group study is descriptive, and the absence of a comparator limits causal interpretation.
12. What the Result Does, and Does Not, Mean
The main result is a description of adverse events recorded in a small, treated group during the registry-defined observation period. The registry reports 19 participants at risk for the lusutrombopag group, 19 participants affected in the other-adverse-event count, 1 participant with a serious adverse event, and 0 deaths. It also lists three serious-event terms, each at 5.3%. These numbers summarize the observations recorded for this study.
They do not establish that lusutrombopag caused or prevented any particular event. Adverse events can occur during treatment without being caused by treatment, and the registry defines treatment-related events through investigator judgment. The posted serious-event terms do not establish treatment attribution. Conversely, the lack of a recorded death in this study does not establish that the risk of death is zero.
The single-group design also means there is no concurrent control result against which to judge whether the observed event counts are higher or lower than under another treatment. A comparison with a different study would not automatically solve this problem because differences in populations, follow-up, event definitions, and reporting can affect counts. No comparative effect estimate is reported in the registry record.
The findings are limited to participants who enrolled and were treated, as defined for the primary outcome, and to the stated safety follow-up. Participants’ treatment durations varied, with a median of 148 days and a range of 10-387 days. These results cannot by themselves establish what would happen during longer exposure for all participants or in a broader clinical population.
The study title and objective frame the work as a long-term safety study, and treatment could continue for up to 3 years or until study termination. The actual treatment-time summary and the terminated status should be kept in view when interpreting that aim. The registry does not report the reason for termination, so no explanation should be assigned to it. The appropriate conclusion is bounded: the record documents reported adverse events in the observed treated group, while comparative safety, causal attribution, and population-level risk remain unresolved by these data.
13. Why This Trial Matters Statistically
This trial matters statistically because it illustrates the difference between describing observed events and estimating a comparative treatment effect. Its primary endpoint is a participant count, and its design is single-group and open-label. The posted counts can therefore convey what was recorded among treated participants, but the design does not supply a randomized control contrast.
Safety summaries are especially dependent on clear event definitions and follow-up. The registry distinguishes adverse events, serious adverse events, and treatment-related adverse events. Keeping these categories separate prevents a common interpretive error: treating every event that occurs after treatment begins as caused by treatment, or treating seriousness as evidence of causation. The reported terms and counts need to be read with the registry’s definitions in mind.
The reported treatment-duration variation is also statistically relevant. A participant count records whether an event was observed, while not accounting for how long each participant was exposed. General statistical principle: exposure-adjusted rates can be useful when time at risk differs, but such calculations require appropriate data. The registry entries do not report those rates, so the posted summaries should not be mistaken for them.
The study also makes the limits of small descriptive datasets visible. An event count in a group of 19 provides limited information about uncommon outcomes and about the range of possible population risks. This does not make the observations uninformative; it means their scope is narrow. Careful reporting of counts, event definitions, timeframes, and uncertainty is important to avoid interpreting a descriptive safety record as stronger evidence than it can provide.
Finally, the separate planning assumptions illustrate why design calculations must be distinguished from results. A planning illustration based on a hypothetical two-arm comparison is not the design of this single-group study, and it is not observed power. Keeping those concepts separate helps readers understand what the study actually measured and what questions require other evidence.
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 principal limitation is the absence of a comparator group. Since this was a single-group, open-label study, the adverse-event counts cannot be contrasted with outcomes under another treatment within the same trial. The results are descriptive and do not isolate the effect of lusutrombopag from other possible causes of events.
Enrollment was 19, which limits the information available about uncommon events and makes the observed counts imprecise as estimates of broader risks. No confidence intervals are stated in the registry record. The registry reports a median treatment time of 148 days and a range of 10-387 days, so treatment exposure was not uniform. The posted participant counts do not adjust for differences in exposure time.
The registry identifies the study as terminated but does not report why. The planned maximum treatment period was up to 3 years or until termination, while the reported treatment-time summary reflects shorter and varying observed exposure. The record does not explain how termination affected follow-up, whether all participants were followed after stopping treatment, or whether the endpoint observation window was complete for each participant.
Information about missing data, discontinuations, event adjudication, treatment-related event counts, and statistical analysis procedures is not reported in the registry record. The record lists secondary outcomes, but their results are not included in the registry record described for this analysis. Multiplicity handling and any prespecified hierarchy among outcomes are also not reported. These omissions limit assessment of completeness and prevent reconstruction of a detailed analysis.
Finally, the primary outcome is a broad count of participants with adverse events. It does not, on its own, describe event frequency, duration, recurrence, or exposure-adjusted risk. The listed serious-event terms and percentages should not be interpreted as causal or additive estimates. These limitations constrain what the registry results can establish beyond documenting the reported events in the observed group.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: An Open-label Safety Study of Lusutrombopag (S-888711) in Adults With Chronic Immune Thrombocytopenia (ITP) — NCT01129024.
- Registry record last updated 2021-02-26; status last verified 2021-02.
- Results first posted 2021-02-26.
- 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 describes NCT01129024, a phase 2, open-label, single-group safety study of lusutrombopag in adults with relapsed persistent or chronic immune thrombocytopenia, with or without prior splenectomy. The study enrolled 19 participants and is recorded as terminated. The primary objective was long-term safety assessment.
Participants received oral lusutrombopag starting at 0.5 mg once a day, with dose adjustment based on platelet counts. Treatment could continue for up to 3 years or until study termination. The primary safety timeframe extended from first extension-study dose through 6 weeks after the last dose; median time on treatment was 148 days, with a range of 10-387 days.
The registry reports 19 participants affected in the other-adverse-event count, 1 participant with a serious adverse event, and 0 deaths. Thrombocytopenia, overdose, and suicidal ideation are each listed at 5.3% among the serious-event terms. With no comparator group, these results describe the observed treated group rather than a comparative treatment effect. The reason for termination and detailed statistical methods are not reported in the registry record.