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 Extension Study to Evaluate the Safety and Tolerability of Perampanel (E2007) Administered as an Adjunctive Therapy in Epilepsy Subjects (NCT02427607), a na phase 3 study. The primary outcome is Number of Participants With Treatment-Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs) as a Measure of Safety and Tolerability of Perampanel.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02427607 |
| Phase | Phase 3 |
| Condition | Epilepsy |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 7 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Eisai Co., Ltd. |
| Results posted | Yes |
2. Clinical Question
Population
Participants with epilepsy who entered an extension study after participating in Study 332. The safety analysis set was defined as participants who signed informed consent, received at least one dose of study drug, and had at least one post-dose safety assessment. The registry reports enrollment of 7.
Intervention
Perampanel as adjunctive therapy. Participants started at the dose they were receiving at the end of their participation in Study 332; doses could be adjusted based on clinical judgment.
Comparator
There was no separate comparator group. The study is described as open-label, single-group, and without allocation to treatment groups. Its results therefore do not provide a like-for-like comparison with another treatment or with no treatment.
Primary question
The primary outcome counts participants with treatment-emergent adverse events and serious adverse events as a measure of safety and tolerability. Safety monitoring also included withdrawal from treatment, clinical chemistry laboratory tests, vital signs, and weight.
This is a follow-on safety question, not a randomized test of perampanel against a control. The registry describes participants continuing from an earlier study, with their starting dose carried over and subsequent dose adjustments permitted by clinical judgment. The primary outcome focuses on whether participants experienced adverse events during the extension, rather than on a comparative estimate of benefit or harm.
The safety outcome timeframe ran from the first dose until perampanel became commercially available, up to approximately 1 year 5 months. The registry's definition of treatment-emergent adverse events also specifies a post-treatment window and a baseline reference from Study 332. The record reports 7 participants at risk for both serious and other adverse events; the posted results list 0 participants with serious events and 6 with other events.
3. Trial Design
This was a Phase 3, open-label extension study of perampanel used as adjunctive therapy in participants with epilepsy. The registry describes a single-group design with no allocation to different treatment groups. Enrollment was 7, and the study status is completed. It began on 2015-05-12, with primary completion on 2016-09-21.
Participants entered the extension after taking part in Study 332. They began this study at the dose they were receiving at the end of their participation in that earlier study. The registry says doses could be adjusted based on clinical judgment. It describes the study as continuing until perampanel was commercially available. The primary outcome timeframe is stated as running from the first study-drug dose until commercial availability, up to approximately 1 year 5 months.
Because the study was open-label and single-group, participants and study personnel were not masked to the treatment, and there is no separate concurrent control group in the registry record. This design can describe safety observations among those who entered and remained in the extension, but it cannot separate treatment effects from other influences through a randomized comparison. The registry does not report a comparative efficacy endpoint.
The record lists one primary outcome measure and no statistical analyses. The primary measure is a participant count for treatment-emergent adverse events and serious adverse events. Additional safety monitoring included adverse events, withdrawal from treatment, clinical chemistry laboratory tests, vital signs, and weight. The record does not report a detailed statistical plan, sample-size justification, or interim analysis plan.
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: This study was conducted at 8 centers in Japan during the period of 12 May 2015 to 21 Sep 2016. E2007-J000-341 is an open-label extension of E2007-G000-332.
Overall Study
| Stage | Perampanel |
|---|---|
| STARTED | 7 |
| COMPLETED | 6 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | Perampanel |
|---|---|
| Withdrawal by Subject | 1 |
Analysis population for the primary outcome, as defined in the registry: Safety analysis set included all participants who signed informed consent and received at least one dose of study drug, and had at least one post-dose safety assessment in Study 341.
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: Safety analysis set included all participants who signed informed consent and received at least one dose of study drug, and had at least one post-dose safety assessment in Study 341.
| Characteristic | Unit | Perampanel |
|---|---|---|
| Participants analysed | 7 | |
| Age, Continuous | Years | 35.3 (SD 19.20) |
| Sex: Female, Male: Female | Participants | 3 |
| Sex: Female, Male: Male | Participants | 4 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Treatment-Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs) as a Measure of Safety and Tolerability of Perampanel, measured over From first dose of study drug until perampanel was commercially available, up to approximately 1 year 5 months.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts participants with treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs). It is reported as a number of participants, so it describes how many people experienced an event rather than the total number of events or an event rate over person-time.
The registry defines TEAEs as adverse events that emerged from the first dose through the last visit of Study 341, or on or after 30 days since the last dose in Study 341, whichever came later, and that had been absent at pretreatment baseline in Study 332. Treatment-related TEAEs were defined separately as events the investigator considered possibly or probably related to study treatment. An SAE was defined by specified consequences, including death, disability or incapacity, birth defect, inpatient hospitalization or prolongation of hospitalization, or a life-threatening event.
Counting participants with adverse events is a direct way to describe how often safety events were observed in a small extension cohort. It does not by itself establish that perampanel caused an event, and the primary count does not quantify severity for events that do not meet the SAE definition. The endpoint is used for safety and tolerability monitoring, not to estimate a comparative treatment effect.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted results list 7 participants at risk for serious adverse events and 0 participants with a serious adverse event. For other adverse events, 7 participants were at risk and 6 had an event. The record also lists 0 deaths. These are descriptive counts from a small, single-group extension cohort; they are not estimates from a randomized comparison.
The difference between the two event categories is important for reading the results. An SAE is identified by the seriousness criteria stated in the registry, while the other adverse-event count captures events outside that serious category. The reported count of 6 participants with other adverse events therefore does not mean that 6 participants had serious events. Nor does the count indicate how many separate events occurred, how long each lasted, or whether each was considered treatment-related.
These counts describe the participants included in the posted safety results, not every person with epilepsy who might receive perampanel. In an extension study, participants have already taken part in an earlier study, and entry into continued follow-up may select a group that differs from people who did not enter the extension. The single-group design also offers no concurrent control for interpreting the observed events. Thus the registry can describe what was recorded in this cohort, but the counts alone cannot attribute events to the drug or establish how the results compare with another treatment or with no treatment.
The zero count for serious adverse events is an observation in this cohort, not proof that serious events cannot occur. The small number at risk limits the amount of safety experience represented. Conversely, the report of other adverse events in 6 participants is not, on its own, evidence that all of those events were caused by treatment or that they had a particular clinical importance. The registry does not provide event-level descriptions or treatment-related classifications in the posted results represented.
No statistical analyses are listed in the registry record. The results are therefore best read as participant counts rather than as model-based estimates, hypothesis tests, or adjusted comparisons. The record does not report confidence intervals or a statistical comparison. The counts convey the observed pattern in this extension, while leaving uncertainty about how that pattern would generalize beyond the cohort.
9. Statistical Methods Explained
The registry describes a single-group safety study and reports a participant-count outcome. That makes the basic interpretation descriptive: count how many participants experienced the specified outcome among those at risk. The posted results give 7 participants at risk for serious adverse events and 7 at risk for other adverse events. They report 0 participants with serious events and 6 with other events. The record lists no statistical analyses, so these results should not be read as outputs from a comparative model or a hypothesis test.
What does a participant count measure?
A participant count records whether people experienced an outcome during the stated observation period. It differs from a count of all event episodes: one participant may have more than one event, but a participant-level outcome counts that person once for the relevant category. The primary measure is specified in terms of participants. The registry does not give the total number of event episodes in the results.
Participant counts also differ from event rates. A rate uses information about time at risk, whereas the posted result is a count of participants with events. The timeframe gives the period over which safety was monitored, but the registry does not report person-time or an event-rate analysis. The counts therefore describe the number of affected participants in the study group without adjusting for differences in follow-up duration.
Why does the single-group design matter?
A randomized comparison estimates differences between groups assigned to different conditions under the study's design. This extension has no separate comparator group: it is open-label and single-group. Its safety results can describe events observed among participants receiving perampanel in this study, but they cannot establish whether the observed counts would have been higher or lower under another treatment or no treatment. Without a concurrent comparison, other influences on adverse events cannot be distinguished from treatment effects by the design alone.
Open-label means masking was absent. Knowledge of treatment can affect reporting, assessment, or decisions about dose changes and follow-up. The registry notes that doses could be adjusted based on clinical judgment. The record does not describe procedures intended to prevent knowledge of treatment from influencing outcome assessment.
How should zero observed events be understood?
A count of zero means that no participant in the reported at-risk group was recorded as having that outcome during the defined observation period. It does not establish that the underlying risk is zero. With a small cohort, the observed count is compatible with substantial uncertainty about what could occur in a broader population. A confidence interval can express uncertainty around an estimate, but no confidence interval is reported in the registry record for these outcomes.
Likewise, the count of 6 participants with other adverse events establishes that events were recorded for those participants, but it does not show that the study drug caused them. Causal attribution requires more than observing an event after treatment begins. The registry distinguishes treatment-related TEAEs as events judged possibly or probably related by the investigator, but the posted results do not give a count for that category.
What do the endpoint definitions contribute?
The endpoint definition sets the time window and the event classification. TEAEs were defined relative to the first dose, the last visit, a period after the last dose, and baseline in Study 332. SAEs were defined by serious outcomes such as death, hospitalization, or life-threatening events. These definitions determine which observations belong in each category. They do not, on their own, establish that an event was caused by treatment.
The registry also says that safety was assessed through adverse events, treatment withdrawal, clinical chemistry tests, vital signs, and weight. The primary outcome title concerns TEAEs and SAEs, while the record does not provide numerical results for each additional monitoring component in the registry record. Results for those components should not be inferred from the adverse-event counts.
What is not available for statistical assessment?
The registry lists one outcome measure and no statistical analyses. It does not report the statistical plan, a sample-size justification, an interim-analysis plan, confidence intervals, or adjusted estimates. Consequently, there is no basis in the registry record for describing a formal test of a treatment effect or the precision of an estimated comparison. General concepts such as confidence intervals explain how statistical uncertainty can be expressed, but no interval should be attributed to these results unless it is reported.
For this design, the central statistical reading is the cohort-level description: how many participants were at risk and how many had the recorded outcome. The small size and lack of a comparator limit interpretation. The counts are useful for reporting observed safety experience, but they do not establish a causal effect, a comparative risk, or the frequency expected in a larger or different population.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome measure, concerning participants with treatment-emergent adverse events and serious adverse events. It does not report a broader hierarchy of primary and secondary endpoints or a multiplicity-adjustment plan. Multiplicity refers, in general, to the interpretive problem that arises when many statistical tests or outcomes are examined; without a reported analysis plan, it is not possible to assess how such issues were handled. No statistical analyses are listed.
The registry defines the safety analysis set as participants who signed informed consent, received at least one dose of study drug, and had at least one post-dose safety assessment in Study 341. The adverse-event summaries report 7 participants at risk in each category. The record does not describe how missing safety assessments were handled, whether any participants withdrew before the end of follow-up, or how incomplete observations were treated.
The timeframe is described as extending from the first dose until perampanel was commercially available, up to approximately 1 year 5 months. The record does not provide participant-level follow-up durations or explain whether the observation period differed among participants. It also does not report a method for handling censoring, missing outcome status, or other incomplete safety information.
Because the study is single-group and no statistical analyses are listed, there is no reported adjustment for baseline differences or other covariates. The registry record also does not report a sample-size justification or interim-analysis plan. These omissions limit assessment of the intended statistical procedures; they do not justify guessing what procedures may have been used.
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 |
|---|---|---|---|
| Perampanel | 0 | 7 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Perampanel | 0 of 7 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Perampanel | 6 of 7 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Perampanel |
|---|---|---|
| Nasopharyngitis | Infections and infestations | 3 of 7 |
| Influenza | Infections and infestations | 1 of 7 |
| Fall | Injury, poisoning and procedural complications | 1 of 7 |
| Head injury | Injury, poisoning and procedural complications | 1 of 7 |
| Humerus fracture | Injury, poisoning and procedural complications | 1 of 7 |
| Diabetes mellitus | Metabolism and nutrition disorders | 1 of 7 |
| Hypercholesterolaemia | Metabolism and nutrition disorders | 1 of 7 |
| Hyperuricaemia | Metabolism and nutrition disorders | 1 of 7 |
The serious adverse-event results report 0 participants affected among 7 at risk. The other adverse-event results report 6 participants affected among 7 at risk. The registry also records 0 deaths. These are participant counts, not counts of individual event episodes, and they describe the reported safety cohort over the defined study period.
Serious adverse events are classified by the registry's criteria, which include events resulting in death, disability or incapacity, birth defect, inpatient hospitalization or its prolongation, or a life-threatening event. The separate count for other adverse events should not be confused with the serious-event count. The record does not list serious adverse-event terms among its top reported terms, and it does not give an event-by-event account in the results.
The results do not state that the other adverse events were judged treatment-related. The registry's definition of treatment-related TEAEs depends on investigator assessment, but no corresponding count is reported. Since the study is open-label, single-group, and includes only 7 participants at risk, the event counts describe what was observed in this extension cohort; they do not establish causation or quantify comparative risk.
12. What the Result Does, and Does Not, Mean
The posted results describe safety observations in a small extension cohort receiving adjunctive perampanel. Among 7 participants at risk, 0 had a serious adverse event, while 6 had an other adverse event. The registry reports no deaths. These counts are the central numerical findings for the safety outcomes in the record.
They do not show that perampanel caused the events. Adverse events can occur during treatment without being caused by treatment, and the study has no concurrent control group to help distinguish those possibilities. The record defines treatment-related events through investigator judgment but does not report a treatment-related event count. It also does not provide event-level details that would allow readers to assess the nature, duration, or clinical course of the other adverse events.
The zero serious-event count is limited to the participants and observation period reported. It should not be interpreted as evidence that serious adverse events are impossible or that no serious events would occur in a larger population or during a different duration of treatment. The small cohort means the observed count gives limited information about less frequent outcomes. No confidence interval or comparative estimate is reported to characterize statistical precision.
The study also cannot answer whether perampanel is safer or less safe than another treatment. The design is open-label and single-group, with no randomized comparator. Dose adjustments were allowed based on clinical judgment, and participants entered from a previous study. These features make the results a description of continued treatment in this cohort rather than a controlled estimate of a treatment effect.
Accordingly, the findings support a narrow conclusion: adverse events were recorded in this extension, including other adverse events in 6 participants, and no serious adverse events or deaths were reported among the 7 participants at risk. The registry does not report enough comparative or inferential information to draw broader conclusions about causality, relative safety, or expected event frequency elsewhere.
13. Why This Trial Matters Statistically
Extension studies address a distinct statistical question from randomized treatment trials. They can document safety observations among participants who continue into follow-up after an earlier study. In this record, participants carried forward their perampanel dose from Study 332, with later dose adjustments permitted by clinical judgment. The reported outcome counts therefore describe continued treatment in that setting.
The design matters when interpreting the counts. An open-label, single-group study can reveal which events were recorded in the cohort, but without a concurrent comparator it cannot estimate a contrast between treatment strategies. The record's 0 serious adverse events and 6 participants with other adverse events are informative as descriptive observations, not as comparative effects.
The small cohort also highlights the distinction between observing no event and establishing that an event is rare or absent. A zero count in a limited group is not a guarantee of zero risk in a broader population. The registry does not report precision estimates, so readers should keep the uncertainty associated with the size and design of the study in mind without treating the counts as population-wide rates.
Finally, the record illustrates why outcome definitions and analysis reporting matter. It specifies what counts as a treatment-emergent event and what makes an event serious, while also describing additional safety monitoring. Yet no statistical analyses are listed, and the record does not report results for every monitoring component or a treatment-related event count. Clear distinctions between observed counts, causal attribution, and comparative inference are essential when reading safety evidence from an extension study.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The most important limitation is the absence of a comparator. The study is open-label and single-group, so the results cannot establish how safety outcomes differ from those under another treatment or no treatment. Dose changes could be made based on clinical judgment, and the record does not report a standardized dose comparison.
Enrollment was 7, leaving a small group for describing safety outcomes. The posted results report no serious adverse events, but a zero count in this cohort does not rule out serious events in a larger population. The study's extension setting also means participants had previously taken part in Study 332; the findings may not represent people who did not enter an extension study.
The registry does not provide detailed event-level descriptions, counts of event episodes, participant-level follow-up, or a count of events judged treatment-related. The timeframe is stated as up to approximately 1 year 5 months, but the record does not report whether follow-up duration varied by participant. Numerical results for the listed laboratory, vital-sign, weight, and treatment-withdrawal monitoring are not reported in the record details.
No statistical analyses are listed. The record does not report a statistical plan, sample-size justification, confidence intervals, missing-data procedures, or interim analyses. As a result, the posted participant counts cannot be supplemented with a reported estimate of precision or a formal comparative analysis. These limitations constrain interpretation to the observed safety counts in this particular extension cohort.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: An Open-label Extension Study to Evaluate the Safety and Tolerability of Perampanel (E2007) Administered as an Adjunctive Therapy in Epilepsy Subjects — NCT02427607.
- Registry record last updated 2018-07-02; status last verified 2017-09.
- Results first posted 2018-07-02.
- 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
This completed Phase 3 study was an open-label, single-group extension of perampanel as adjunctive therapy in participants with epilepsy. Enrollment was 7. The study began on 2015-05-12, and primary completion was 2016-09-21.
Participants began at the dose they received at the end of Study 332, with dose adjustment permitted based on clinical judgment. The primary outcome counted participants with treatment-emergent adverse events and serious adverse events. Its timeframe extended from the first dose until perampanel became commercially available, up to approximately 1 year 5 months.
The posted safety results list 7 participants at risk for each adverse-event category, 0 participants with serious adverse events, 6 with other adverse events, and 0 deaths. The registry lists one outcome measure and no statistical analyses. Because there was no comparator group, these results are descriptive observations rather than estimates of comparative treatment effects.