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 Efficacy and Safety of Oral E5501 Plus Standard of Care for the Treatment of Thrombocytopenia in Adults With Chronic Immune Thrombocytopenia (Amendment 02) (NCT01438840), a randomized phase 3 study. The primary outcome is Number of Weeks With Platelet Count Greater Than or Equal to 50 x 10^9/L During 6-Month Treatment Period.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01438840 |
| Phase | Phase 3 |
| Condition | Chronic Thrombocytopenia, Immune Thrombocytopenia |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 49 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Eisai Inc. |
| Results posted | Yes |
2. Clinical Question
The core study asked whether adding avatrombopag to standard of care was associated with more weeks of platelet response than adding placebo to standard of care in adults with chronic immune thrombocytopenia. The registry describes participants as adults who had received at least 1 prior ITP therapy. The primary endpoint counted weeks during the 6-month treatment period in which the platelet count met the stated threshold, in the absence of rescue therapy.
Population
Adults with chronic immune thrombocytopenia who had received at least 1 prior ITP therapy. The primary analysis population was the Full Analysis Set, defined as all participants randomized into the core study.
Intervention
Oral avatrombopag plus standard of care in the randomized core study. The registry describes once-daily treatment with flexible dosing over 26 weeks.
Comparator
Placebo plus standard of care, also administered orally once daily in the core study. The study was described as double-blind and placebo-controlled, with triple masking recorded in the registry.
Primary question
How did the cumulative number of weeks with platelet count at or above 50 x 10^9/L during Week 1 to Week 26 compare between the randomized groups?
The registry also describes an open-label extension intended to evaluate long-term safety and tolerability of avatrombopag. That extension addresses a different question from the blinded core-study efficacy comparison. Its participants and event counts should therefore be kept separate from the randomized core-study comparison when interpreting the primary endpoint.
3. Trial Design
This was a Phase 3, multicenter, randomized, double-blind, placebo-controlled, parallel-group trial. The registry records triple masking, but does not identify which groups of people were masked. The total enrollment was 49. In the core study, 17 participants were assigned to placebo and 32 to avatrombopag. Both groups received standard of care alongside the assigned study treatment.
The core-study treatment period was 26 weeks. Avatrombopag was taken orally once daily, with a starting dose of 20 mg and a flexible-dose approach. The registry describes available dose levels of 5 mg, 10 mg, 20 mg, 30 mg, or 40 mg and titration within a stated minimum of 5 mg and maximum of 40 mg. The placebo group followed a corresponding flexible-dose design. Detailed rules governing dose adjustment are not reported in the registry record.
The primary endpoint covered Week 1 to Week 26 and was analyzed in the Full Analysis Set, which the registry defines as all randomized participants. The stated endpoint definition excludes weeks following rescue therapy from the platelet-response count. The registry names two secondary outcomes: reduction in use of concomitant ITP medication and platelet count at or above 50 x 10^9/L at Day 8. Results for those outcomes are not reported in the registry record.
Participants meeting extension eligibility requirements could enter an open-label phase in which they received avatrombopag. The registry describes that phase as intended to evaluate long-term safety and tolerability. Because the extension was open label and followed the core study, it does not provide the same randomized, blinded comparison as the core phase. The registry record does not report the detailed operational procedures for extension enrollment or follow-up.
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: A total of 100 participants were screened in study. Of these 100 participants, 51 were screen failures and 49 were randomized into the study.
Core Study
| Stage | Placebo (Core Study) | Avatrombopag (Core Study) | Avatrombopag (Extension Phase) |
|---|---|---|---|
| STARTED | 17 | 32 | 0 |
| COMPLETED | 1 | 22 | 0 |
| NOT COMPLETED | 16 | 10 | 0 |
Reasons for not completing this period:
| Reason | Placebo (Core Study) | Avatrombopag (Core Study) | Avatrombopag (Extension Phase) |
|---|---|---|---|
| Adverse Event | 0 | 3 | 0 |
| Lack of Efficacy | 15 | 7 | 0 |
| Withdrawal of consent | 1 | 0 | 0 |
Extension Phase
| Stage | Placebo (Core Study) | Avatrombopag (Core Study) | Avatrombopag (Extension Phase) |
|---|---|---|---|
| STARTED | 0 | 0 | 39 |
| COMPLETED | 0 | 0 | 29 |
| NOT COMPLETED | 0 | 0 | 10 |
Reasons for not completing this period:
| Reason | Placebo (Core Study) | Avatrombopag (Core Study) | Avatrombopag (Extension Phase) |
|---|---|---|---|
| Adverse Event | 0 | 0 | 3 |
| Lost to Follow-up | 0 | 0 | 1 |
| Withdrawal by Subject | 0 | 0 | 3 |
| Lack of Efficacy | 0 | 0 | 2 |
| Other | 0 | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: Full Analysis Set (Core Study): All participants who were randomized into the study.
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 | Placebo (Core Study) | Avatrombopag (Core Study) | Total |
|---|---|---|---|---|
| Participants analysed | 17 | 32 | 49 | |
| Age, Continuous | Years | 41.2 (SD 14.7) | 46.4 (SD 14.2) | 44.6 (SD 14.44) |
| Sex: Female, Male: Female | Participants | 8 | 23 | 31 |
| Sex: Female, Male: Male | Participants | 9 | 9 | 18 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Weeks With Platelet Count Greater Than or Equal to 50 x 10^9/L During 6-Month Treatment Period, measured over Week 1 to Week 26.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Full Range |
| Unit | Weeks |
| Endpoint classification | Time-to-Event Analysis |
The primary outcome was the number of weeks with platelet count greater than or equal to 50 x 10^9/L during the 6-month treatment period. Its timeframe was Week 1 to Week 26. The endpoint was defined as the cumulative number of weeks meeting that platelet threshold during core-study treatment, in the absence of rescue therapy. It therefore represents a repeated measure summarized as a total across the treatment period, rather than a single platelet count at one visit.
This type of endpoint can reflect how consistently a participant met the stated threshold over the treatment period. A participant with more qualifying weeks has a larger cumulative response value under the registry definition. The endpoint is clinically interpretable in terms of time spent at or above a specified platelet count, while retaining information across multiple weeks rather than relying solely on one scheduled measurement. That is a general rationale for cumulative response measures, not an additional claim about how this protocol selected the endpoint.
The registry reports the endpoint using medians and full ranges. The placebo group had a median of 0 weeks, with a range from 0 to 2. The avatrombopag group had a median of 12.4 weeks, with a range from 0 to 25. These summaries describe the observed distributions, but do not by themselves provide an adjusted difference between groups or a confidence interval for that difference. The registry’s comparison used a Wilcoxon (Mann-Whitney) test.
Rescue therapy is relevant to interpretation because the endpoint definition excludes qualifying weeks in its presence. The detailed rules for handling rescue therapy, missing weekly measurements, and incomplete follow-up are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted results describe different distributions of cumulative platelet-response weeks in the two randomized core-study groups. The placebo group’s median was 0 weeks, and its full range was 0 to 2. The avatrombopag group’s median was 12.4 weeks, and its full range was 0 to 25. Thus, the reported median and range for the avatrombopag group were higher and wider than those reported for placebo. These are descriptive summaries; they do not show how every participant fared, and the ranges indicate that individual observations varied within each group.
The sponsor reported a Wilcoxon (Mann-Whitney) comparison with p < 0.001. This is a rank-based comparison of the observed group distributions, rather than a reported estimate of the difference between group medians. The p-value indicates that the observed rank separation would be unusual under the test’s null hypothesis of no distributional difference, subject to the test assumptions. It does not state the size or precision of a treatment effect, nor does it give the probability that the null hypothesis is true.
The numerical summaries are based on 17 participants in the placebo group and 32 in the avatrombopag group, within a total enrollment of 49. The unequal group sizes are part of the reported study design and should be kept in view when considering how much information each group contributes. The registry identifies the Full Analysis Set as all participants randomized into the core study. It does not give additional detail about missing endpoint observations or the handling of incomplete weekly measurements.
The ranges overlap at 0, so the group summaries should not be read as implying that all participants in one arm had more response weeks than all participants in the other. Nor does a small p-value establish that the observed difference is free of bias or that the result applies unchanged outside the enrolled study population. The registry record does not report a confidence interval for a between-group effect, an adjusted effect estimate, or a separate estimate of uncertainty around the medians. Consequently, the direction of the descriptive contrast and the reported rank-test result are available, but the precision of a treatment-effect estimate cannot be assessed from these results alone.
The posted data address the stated core-study endpoint, not every clinical outcome. The listed secondary outcomes concern concomitant ITP medication use and a Day 8 platelet threshold, but their results are not reported in the registry record. The long-term extension is open label and is presented as a safety and tolerability phase; it should not be interpreted as a further blinded efficacy comparison. The observed results are statistical findings from this trial and do not, on their own, determine an individual treatment decision.
9. Statistical Methods Explained
The primary endpoint is a cumulative count of weeks meeting a platelet threshold. The registry summarizes it with the median and full range, then reports a Wilcoxon (Mann-Whitney) test for the two-group comparison. This combination is suitable for describing an outcome whose distribution may not be well represented by a mean and standard deviation. The reported values are medians, not averages, and the full range gives the lowest and highest observed values in each group.
What does a median describe?
In general, the median is the central value after observations are ordered. It is less affected by unusually high or low observations than the arithmetic mean. A median does not describe the full shape of a distribution, however. Two groups can have different ranges, clustering, or patterns of observations even when their medians are similar. Here the registry also reports full ranges, which convey the spread from the lowest to the highest recorded outcome but not how observations are distributed between those endpoints.
What does the Wilcoxon (Mann-Whitney) test compare?
In general, this rank-based test orders observations from both groups and evaluates whether values from one group tend to be higher or lower than values from the other. It does not require the outcome to follow a normal distribution in the way a standard two-sample t-test does. Its result is often described as a comparison of distributions or relative ranks. It is not automatically a test of a difference in medians: that narrower interpretation needs additional assumptions about the shapes of the distributions. Those assumptions are not described in the registry record.
The reported p-value is p < 0.001. In general, a p-value measures how incompatible the observed test statistic is with a specified null model, if that model and the test assumptions hold. It is not the probability that the treatment has no effect, and it does not measure effect size. A p-value also cannot show whether the result is clinically important or how precisely the effect has been estimated. For those questions, an effect estimate and confidence interval are useful, but such a between-group estimate and interval are not reported in the registry record.
Why does the endpoint definition matter?
The endpoint counts weeks meeting the platelet threshold during the stated treatment window, and it excludes response weeks in the presence of rescue therapy. This definition determines what is counted and how the result should be understood. It differs from a single measurement at the end of treatment: a cumulative count can reflect multiple weeks of response. The registry record does not explain how weeks with missing platelet measurements were treated, how rescue therapy affected subsequent observations, or whether any other endpoint rules were applied.
How should the sample-size illustrations be read?
In general, planning illustrations estimate the number of participants that might be needed under specified assumptions. The stated assumptions for the illustrations include a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect defined as a stated fraction of the observed effect. Such illustrations are not the trial’s observed power and do not establish that the original trial was designed using those assumptions. The registry record does not report the trial’s sample-size justification or the assumptions used to plan enrollment.
What information is unavailable for judging precision?
Confidence intervals describe a range of effect values compatible with data and a statistical model, while making the uncertainty in an estimate more visible than a p-value alone. General interpretation depends on the method used and its assumptions. The registry does not report a confidence interval for a two-arm effect on this median-type endpoint. The posted group medians and ranges remain informative descriptive statistics, but they do not replace an interval estimate for a specified between-group contrast.
There is one sponsor-reported analysis for the primary comparison in the registry record. The record does not describe adjustment for multiple testing, a hierarchy among outcomes, or interim analyses. The study lists secondary outcomes, but their results are not reported in the registry record. These omissions limit assessment of the broader analysis strategy and of how the reported primary p-value relates to other planned tests.
10. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| Wilcoxon (Mann-Whitney) | not reported | < 0.001 |
The sponsor’s reported primary comparison used a Wilcoxon (Mann-Whitney) test and gave p < 0.001 for the placebo and avatrombopag groups. That is the inferential result reported in the registry record. The posted endpoint summaries are medians with full ranges: 0 weeks with a range from 0 to 2 for placebo, and 12.4 weeks with a range from 0 to 25 for avatrombopag.
No recalculated two-arm effect estimate or confidence interval is available for this median-type endpoint. The posted summaries do not yield a reported adjusted difference, and the registry’s own rank-based test is the available sponsor analysis. There is no stated discrepancy between a sponsor analysis and a recalculation. The sponsor’s reported analysis therefore remains the relevant inferential comparison; the descriptive group summaries should not be mistaken for a separate calculated treatment-effect estimate.
The distinction matters because a rank-test p-value and a difference between medians answer different statistical questions. The p-value addresses the rank-based comparison under its test assumptions. The medians and ranges describe each group’s observed endpoint values. Neither result alone supplies a confidence interval for a between-group effect, and the registry record does not report one.
11. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary endpoint and two secondary outcomes. The primary endpoint is cumulative weeks with platelet count at or above 50 x 10^9/L during the core-study treatment period. The secondary outcomes concern reduction in concomitant ITP medication and platelet count at or above 50 x 10^9/L at Day 8. Results for those secondary outcomes are not reported in the registry record.
When several outcomes or statistical tests are considered, the chance of at least one apparently unusual result can increase. General statistical practice may address this through a prespecified testing hierarchy or other multiplicity procedures. The registry record does not report whether such procedures were planned or used, or how the primary and secondary outcomes were ordered for inference. It also does not report interim analyses. The reported primary p-value should therefore be read as the result of the stated test, without assuming that an unreported multiplicity adjustment was or was not applied.
The primary analysis population is defined as the Full Analysis Set: all participants randomized into the core study. The record does not provide further details about exclusions after randomization, the number with observed primary endpoint data, or the handling of missing weekly platelet measurements. It also does not report how rescue therapy and incomplete follow-up were incorporated beyond the endpoint definition’s statement that response weeks in the presence of rescue therapy are not counted. These details matter because missingness and post-randomization events can affect the interpretation of a cumulative outcome.
The trial’s sample-size justification, detailed analysis plan, and specific missing-data procedures are not reported in the registry record. Planning illustrations based on the observed effect are not a substitute for a trial’s prospective sample-size rationale and should not be interpreted as observed power. Without the prespecified analysis details, readers cannot establish from the registry alone whether all analysis decisions followed a prior plan or how sensitivity to missing data was assessed.
12. 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 |
|---|---|---|---|
| Placebo (Core Study) | 1 | 17 | 5.9% |
| Avatrombopag (Core Study) | 9 | 32 | 28.1% |
| Avatrombopag (Extension Phase) | 15 | 47 | 31.9% |
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 |
|---|---|
| Placebo (Core Study) | 10 of 17 |
| Avatrombopag (Core Study) | 31 of 32 |
| Avatrombopag (Extension Phase) | 45 of 47 |
Most frequent serious adverse event terms
| Event term | Organ system | Placebo (Core Study) | Avatrombopag (Core Study) | Avatrombopag (Extension Phase) |
|---|---|---|---|---|
| Thrombocytopenia | Blood and lymphatic system disorders | 0 of 17 | 1 of 32 | 3 of 47 |
| Vomiting | Gastrointestinal disorders | 0 of 17 | 2 of 32 | 2 of 47 |
| Headache | Nervous system disorders | 0 of 17 | 2 of 32 | 2 of 47 |
| Platelet count decreased | Investigations | 0 of 17 | 1 of 32 | 2 of 47 |
| Food poisoning | Gastrointestinal disorders | 0 of 17 | 1 of 32 | 1 of 47 |
| Mouth haemorrhage | Gastrointestinal disorders | 0 of 17 | 1 of 32 | 1 of 47 |
| Nausea | Gastrointestinal disorders | 0 of 17 | 1 of 32 | 1 of 47 |
| Polyserositis | General disorders | 0 of 17 | 1 of 32 | 1 of 47 |
| Urinary tract infection | Infections and infestations | 0 of 17 | 1 of 32 | 1 of 47 |
| Cerebrovascular accident | Nervous system disorders | 0 of 17 | 1 of 32 | 1 of 47 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Placebo (Core Study) | Avatrombopag (Core Study) | Avatrombopag (Extension Phase) |
|---|---|---|---|---|
| Contusion | Injury, poisoning and procedural complications | 4 of 17 | 10 of 32 | 19 of 47 |
| Headache | Nervous system disorders | 2 of 17 | 12 of 32 | 14 of 47 |
| Upper respiratory tract infection | Infections and infestations | 1 of 17 | 6 of 32 | 11 of 47 |
| Epistaxis | Respiratory, thoracic and mediastinal disorders | 3 of 17 | 4 of 32 | 8 of 47 |
| Gingival bleeding | Gastrointestinal disorders | 0 of 17 | 4 of 32 | 8 of 47 |
| Fatigue | General disorders | 1 of 17 | 4 of 32 | 7 of 47 |
| Petechiae | Skin and subcutaneous tissue disorders | 1 of 17 | 4 of 32 | 7 of 47 |
| Thrombocytopenia | Blood and lymphatic system disorders | 0 of 17 | 2 of 32 | 9 of 47 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 0 of 17 | 4 of 32 | 5 of 47 |
| Nasopharyngitis | Infections and infestations | 0 of 17 | 3 of 32 | 5 of 47 |
Serious events with the highest arm-level rate: thrombocytopenia (6.4%), vomiting (6.2%), headache (6.2%), idiopathic thrombocytopenic purpura (5.9%), platelet count decreased (4.3%).
For the randomized core study, 1 of 17 participants in the placebo group and 9 of 32 in the avatrombopag group were recorded as affected by a serious adverse event. These are participant counts, not estimates of a causal effect. The registry also reports other adverse events affecting 10 of 17 participants in the placebo group and 31 of 32 in the avatrombopag group. Definitions, event-level detail, and the duration of observation for these counts are not reported in the registry record.
The open-label extension is recorded separately: 15 of 47 participants were affected by serious adverse events and 45 of 47 by other adverse events. These extension counts should not be combined with the randomized core-study groups or interpreted as a randomized comparison. The extension was open label and has a different role in the study.
Among the listed serious adverse event terms and percentages are thrombocytopenia at 6.4%, vomiting at 6.2%, headache at 6.2%, idiopathic thrombocytopenic purpura at 5.9%, platelet count decreased at 4.3%, and food poisoning at 3.1%. The registry record does not provide enough detail in these figures to determine the event timing, overlap among participants, or comparative risk for each term. Deaths are not reported in the registry record.
13. What the Result Does, and Does Not, Mean
The registry’s core-study summaries show a higher median number of platelet-response weeks in the avatrombopag group than in the placebo group. The full ranges also show variation within both groups, including a value of 0 weeks in each. The sponsor’s Wilcoxon (Mann-Whitney) test reported p < 0.001. Taken together, these findings describe a difference between the observed groups on the specified cumulative endpoint, with a rank-based test result that is inconsistent with a no-difference null model under its assumptions.
The results do not provide a reported between-group effect estimate with a confidence interval. The p-value does not quantify how large the effect is, how precisely it has been estimated, or the probability that a treatment effect exists. Group medians and ranges likewise do not determine the outcome for an individual participant. They summarize observations within the randomized groups and should be interpreted alongside the trial’s population, endpoint definition, and analysis method.
The primary endpoint is specific: weeks meeting a platelet-count threshold during the defined core-study period, with response weeks in the presence of rescue therapy excluded. It is not a complete measure of all symptoms, quality of life, or longer-term outcomes. The registry names secondary outcomes, but their results are not reported in the registry record. The open-label extension has a safety and tolerability purpose and does not provide a blinded randomized efficacy comparison.
Safety counts are also descriptive. The event figures report how many participants were affected in each phase or group; they do not by themselves establish that study treatment caused an event or quantify comparative risk. Differences in group size, observation period, event definitions, and study phase must be considered, and several of those details are not reported in the registry record.
Overall, the posted results support a statistical description of the primary endpoint in this trial, not a conclusion about every possible outcome or every clinical setting. They do not replace individual clinical judgment or provide medical advice. The registry record’s missing details about analysis planning, missing data, and precision should remain part of any interpretation.
14. Why This Trial Matters Statistically
This trial illustrates why endpoint definition and analysis method need to be read together. The primary outcome was not a single platelet count but the cumulative number of weeks meeting a stated threshold during the core treatment period. That construction retains information across weeks, while the exclusion of weeks associated with rescue therapy makes the endpoint definition especially important to interpretation.
The outcome was summarized with medians and full ranges, and the groups were compared using a rank-based test. This is a useful example of why the reported p-value should not be casually translated into a difference between medians. The test evaluates ranks across the observed distributions, whereas medians summarize the center of each group. Without a reported effect estimate and confidence interval, statistical evidence of group separation is clearer than the magnitude and precision of a specific between-group contrast.
The study also makes the distinction between a randomized core phase and an open-label extension visible. The core phase supplies the placebo comparison for the primary question; the extension has a different design and stated purpose. Keeping those phases separate avoids treating safety counts from the extension as though they came from a concurrent randomized comparison.
Finally, the record demonstrates the limits of registry results when methods are incompletely described. The Full Analysis Set is defined, and the primary test is named, but details about missing endpoint data, multiplicity, interim analyses, and sample-size justification are not reported in the registry record. Those omissions do not erase the posted findings, but they constrain how fully readers can assess their robustness and precision.
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 registry record provides group medians and full ranges for the primary endpoint, but does not report a confidence interval or a direct numerical estimate of the between-group effect. The sponsor’s p-value indicates the result of a rank-based test; it does not quantify the size or precision of a treatment-effect contrast. This limits assessment of uncertainty around the difference suggested by the descriptive summaries.
The record defines the Full Analysis Set as all randomized participants but does not report how many had complete primary endpoint observations or how missing weekly platelet counts were handled. The endpoint excludes response weeks in the presence of rescue therapy, but further rules for rescue therapy and follow-up are not reported in the registry record. These details are relevant for an outcome accumulated over multiple weeks.
The registry does not report the sample-size justification, the detailed statistical analysis plan, any multiplicity procedure, or interim analyses. The secondary outcomes are named, but their results are not reported in the registry record. Consequently, it is not possible from the registry record to assess the complete planned outcome set or the handling of all planned tests.
The core study enrolled 49 participants, with 17 in the placebo group and 32 in the avatrombopag group. The size and imbalance of these groups affect the amount of information available in each arm. The registry’s open-label extension has a different design and purpose; its safety counts should not be treated as a randomized comparison with the placebo group.
Some details of the dosing and extension descriptions are not fully specified in the registry record. It also does not report the observation duration associated with the adverse-event counts, detailed event definitions, or deaths. These omissions limit interpretation of safety comparisons. The record describes a specific adult chronic ITP population and a particular treatment period, so generalization beyond that study context requires caution.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Efficacy and Safety of Oral E5501 Plus Standard of Care for the Treatment of Thrombocytopenia in Adults With Chronic Immune Thrombocytopenia (Amendment 02) — NCT01438840.
- Registry record last updated 2018-02-05; status last verified 2018-01.
- Results first posted 2018-01-05.
- 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.
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19. Record Summary
NCT01438840 is a completed Phase 3 randomized, triple-masked, parallel-group study sponsored by Eisai Inc. The registry records enrollment of 49 participants and compares oral avatrombopag plus standard of care with placebo plus standard of care in the core study. Core treatment lasted 26 weeks, with flexible dosing.
The primary endpoint was cumulative weeks with platelet count at or above 50 x 10^9/L from Week 1 to Week 26, excluding response weeks in the presence of rescue therapy. The placebo group had a median of 0 weeks, with a full range of 0 to 2; the avatrombopag group had a median of 12.4 weeks, with a full range of 0 to 25. The sponsor reported a Wilcoxon (Mann-Whitney) test with p < 0.001.
The registry also describes an open-label avatrombopag extension focused on long-term safety and tolerability. Results for the listed secondary outcomes, a confidence interval for a between-group effect, and several details of analysis and missing-data handling are not reported in the registry record.