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 GWP42003-P Oral Solution in Children With Epilepsy With Myoclonic-atonic Seizures (NCT05288283), a randomized phase 3 study. The primary outcome is Part A: Percent Change From Baseline in Epilepsy With Myoclonic-atonic Seizures (EMAS) Associated Seizure Frequency (Myoclonic-atonic, Atonic, Tonic, Clonic, or Tonic-clonic) Over the 14-week Treatment Period.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05288283 |
| Phase | Phase 3 |
| Condition | Seizures Associated With EMAS |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 3 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Jazz Pharmaceuticals |
| Results posted | Yes |
2. Clinical Question
Population
Children and adolescents with epilepsy with myoclonic-atonic seizures (EMAS), described in the record as having EMAS-associated seizures.
Intervention
GWP42003-P oral solution, studied as an adjunctive treatment. The record names the intervention but does not report analyzed efficacy results.
Comparator
Matching placebo. The registry describes a randomized, placebo-controlled comparison.
Primary question
What was the percent change from baseline in EMAS-associated seizure frequency over the 14-week treatment period?
The primary endpoint covered myoclonic-atonic, atonic, tonic, clonic, or tonic-clonic seizures. The clinical question was whether seizure frequency changed during the treatment period in participants assigned to GWP42003-P or placebo. The record also describes a broader aim of assessing efficacy and tolerability in Part A, with a separate long-term safety and tolerability aim for Part B.
The registry does not report analyzed primary endpoint data: it states that the study was terminated before this endpoint was analyzed. Consequently, the record cannot establish the size or direction of a treatment-group difference in seizure frequency. It also cannot show how precisely such a difference was estimated. The question remains clinically relevant, but the posted record does not answer it with comparative efficacy results.
3. Trial Design
This was a randomized, quadruple-masked, parallel-group, placebo-controlled Phase 3 study at multiple sites. The registry lists GWP42003-P and matching placebo as the interventions. Its title identifies children and adolescents with epilepsy with myoclonic-atonic seizures as the intended population. The recorded enrollment is 3.
The study status is terminated. The recorded start date is 2022-10-31, and the recorded primary completion date is 2023-09-28. The primary endpoint timeframe was baseline through up to 14 weeks. The registry says that no data were collected for that endpoint because the study was terminated before it was analyzed. It does not report why the study was terminated.
Randomization is intended to allocate participants to treatment groups by chance, helping limit systematic differences between groups. Masking is intended to reduce the influence of treatment knowledge on participant experiences, caregiver or clinician assessments, and study conduct. Those are general design principles; the registry record does not describe the operational procedures used to implement randomization or masking.
The record describes Part A as an assessment of efficacy and tolerability and Part B as an evaluation of long-term safety and tolerability. It lists secondary outcomes including seizure reductions, total seizure frequency, seizure-free days, caregiver and physician global impression scores, and time to baseline seizure frequency. The record does not report results for these outcomes or clarify which participants entered each part. Detailed eligibility criteria, treatment allocation procedures, study-site information, and the reason for termination are not reported in the registry record.
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 3 participants were enrolled in Part A of the study. One participant was a screen failure, and 2 underwent randomization. Study was terminated prior to Part B.
Overall Study
| Stage | GWP42003-P | Placebo |
|---|---|---|
| STARTED | 1 | 1 |
| COMPLETED | 0 | 0 |
| NOT COMPLETED | 1 | 1 |
Reasons for not completing this period:
| Reason | GWP42003-P | Placebo |
|---|---|---|
| Study Terminated Early | 1 | 1 |
Analysis population for the primary outcome, as defined in the registry: No data collected, as the study was terminated before this endpoint was analyzed.
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 | GWP42003-P | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 1 | 1 | 2 | |
| Age, Categorical: <=18 years | Participants | 1 | 1 | 2 |
| Age, Categorical: Between 18 and 65 years | Participants | 0 | 0 | 0 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 1 | 0 | 1 |
| Sex: Female, Male: Male | Participants | 0 | 1 | 1 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 1 | 1 | 2 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 | 1 | 1 |
| Race (NIH/OMB): White | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Part A: Percent Change From Baseline in Epilepsy With Myoclonic-atonic Seizures (EMAS) Associated Seizure Frequency (Myoclonic-atonic, Atonic, Tonic, Clonic, or Tonic-clonic) Over the 14-week Treatment Period, measured over Baseline; up to 14 weeks.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was percent change from baseline in EMAS-associated seizure frequency over the 14-week treatment period. The seizure types included in the endpoint were myoclonic-atonic, atonic, tonic, clonic, or tonic-clonic seizures. The registry gives the timeframe as baseline through up to 14 weeks, but it does not provide an analyzed value, a unit beyond percent change, or a description of how seizure frequency was recorded and summarized.
In general, a change-from-baseline endpoint compares a participant’s measurement during follow-up with a reference measurement taken at baseline. Expressing change as a percentage can make the magnitude of change interpretable relative to the starting frequency. Seizure frequency is a clinically relevant measure because it describes how often the specified seizure types occur during the observation period. The meaning of an estimated group difference would depend on the actual values, their variability, and the analysis used.
The registry says no data were collected for this endpoint because the study was terminated before it was analyzed. Thus, there is no posted estimate of percent change, no treatment contrast, and no confidence interval for the primary endpoint. The endpoint’s intended role is clear, but the record does not provide evidence from its analysis.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive fact is that the registry reports no primary endpoint data. It states that the study was terminated before the endpoint was analyzed. There is therefore no posted estimate of percent change from baseline in EMAS-associated seizure frequency, no estimate comparing GWP42003-P with placebo, and no uncertainty interval for that comparison. The record does not support a conclusion about the direction or magnitude of an efficacy difference.
The study is listed as terminated, with recorded enrollment of 3. That enrollment figure should not be mistaken for an analyzed primary-endpoint population. The registry does not state that primary endpoint data were collected, and it explicitly says none were collected for that endpoint. It also does not describe the reason for termination, whether any participants completed a treatment period, or what analyses may have been considered outside the posted results.
The listed secondary outcomes do not fill this gap. They include outcomes such as the number of participants meeting specified seizure-reduction thresholds, total seizure frequency, seizure-free days, and caregiver or physician global impression scores. These are outcome definitions, not results. The registry provides no analyzed values for them. It lists 33 outcome measures and no analyses, but does not indicate that each outcome was assessed or explain the status of every measure.
Safety information is recorded for the GWP42003-P and placebo groups, including serious and other adverse events and deaths. These sparse counts are descriptive registry entries, not a basis for a comparative safety estimate. The record lists one participant at risk in each group for these entries, serious adverse events affecting 1 in the GWP42003-P group and 0 in the placebo group, other adverse events affecting 1 in each group, and 0 deaths in each group. The small recorded counts do not provide a precise estimate of event rates or establish a difference between treatments.
Any sample-size figures calculated as planning illustrations should be read as hypothetical design quantities, not as observed power or as results from this trial. The record’s stated illustration assumptions include a two-sided significance level of 0.05, equal allocation, and a normal approximation. No primary endpoint effect is reported in the record to support an efficacy interpretation. Overall, the posted information describes the intended comparison and the study’s early termination, but does not answer the primary efficacy question.
9. Statistical Methods Explained
Several statistical ideas help clarify what the registry can and cannot establish. The distinctions below are general explanations, not claims about methods used in this study. The registry record does not report a detailed statistical analysis plan, the analysis model, the method used for missing data, or the population included in an efficacy analysis.
What does randomization contribute?
In general, randomization assigns participants to treatment groups by chance. If allocation is implemented as planned, it can reduce systematic differences in measured and unmeasured characteristics between groups. This supports a fair comparison of outcomes, although randomization does not guarantee that groups will be similar in every respect, especially when the amount of information is limited. The registry identifies the study as randomized but does not report the sequence-generation method, concealment procedures, or allocation details.
Why use masking?
Masking is intended to reduce the effects of knowing treatment assignment on behavior, outcome assessment, and study management. The record describes the study as quadruple-masked. It does not specify which roles were masked, how masking was maintained, or whether masking was assessed. These implementation details are not reported in the registry record.
What would a treatment estimate mean?
In general, an estimated treatment contrast summarizes how outcomes differ between assigned groups under a particular analysis definition. A confidence interval describes the range of values compatible with the data and the model assumptions at a stated confidence level. A narrow interval indicates greater precision than a wide interval; an interval that includes values consistent with no difference would leave uncertainty about the direction of the contrast. These concepts require an estimate and its uncertainty. Because the primary endpoint was not analyzed and no estimate is reported, they cannot be applied to the study’s primary efficacy comparison.
Why can seizure-frequency data be statistically challenging?
In general, event counts may vary greatly between participants, and repeated seizure observations from the same participant are not independent. Count data can also show over-dispersion, meaning their variability is greater than would be expected under a simple model with a restrictive variance assumption. When over-dispersion is present, a model that fails to account for it may describe uncertainty poorly. Methods for repeated or over-dispersed counts can address these features, but the registry does not identify a model or say whether such features were assessed in this study.
How should percentage change be understood?
In general, percentage change expresses a follow-up measurement relative to a baseline measurement. Its interpretation depends on how baseline and follow-up frequency were defined, how observations were collected, and how the analysis handled variation across participants. The endpoint title names a percent change from baseline in seizure frequency, but the record does not describe the calculation method, the summary measure, or the model used. No endpoint values are reported, so a numerical change or between-group contrast cannot be interpreted.
What do planning calculations tell a reader?
In general, a sample-size calculation describes the amount of information a planned study might need under specified assumptions about the effect, variability, allocation, and statistical procedure. It is a planning tool, not evidence that an effect was observed. The registry describes its sample-size assumptions as a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It also distinguishes illustrations expressed as participants per arm from time-to-event illustrations expressed as total events. No calculated illustration values or primary endpoint effect are included in the record described for this study. Such planning calculations must not be read as observed power, and they cannot replace an analysis of trial outcomes.
A significance level is a threshold used in some statistical decision procedures; it does not measure the probability that a treatment works. A p-value, if reported, would quantify how compatible the observed data are with a specified null model under the chosen analysis assumptions. It would not describe the size or clinical importance of an effect. The registry reports no analyses, p-values, or confidence intervals for the primary endpoint.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 33 outcome measures, including a primary endpoint and a range of secondary outcomes. When a study evaluates several outcomes or several comparisons, the chance of at least one apparently notable result can increase if each is assessed separately without a prespecified strategy. In general, multiplicity procedures can control or otherwise address this issue. The registry record does not report a multiplicity strategy, the ordering of hypotheses, or which secondary outcomes were intended to support formal claims.
The registry describes the primary endpoint as not having been analyzed because the study was terminated. It lists no analyses. The secondary outcome descriptions therefore should not be read as evidence that findings were observed or tested. Results for these outcomes are not reported in the registry record.
Missing-data methods and analysis populations are also not reported in the registry record. It does not specify whether an intention-to-treat, per-protocol, safety, or other analysis population was defined, nor does it describe how incomplete observations would have been handled. Such choices can affect the interpretation of an estimate, particularly when participants do not contribute all planned measurements. Here, the primary endpoint has no collected data according to the registry, so there is no reported primary analysis from which to assess missing-data handling.
The registry does not describe interim analyses, stopping rules, or a statistical plan for the terminated study. These details should not be inferred from the study’s status. The absence of reported methods means that the record cannot establish how multiplicity, missing observations, or analysis populations would have been addressed.
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 |
|---|---|---|---|
| GWP42003-P | 1 | 1 | 100.0% |
| Placebo | 0 | 1 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| GWP42003-P | 0 of 1 |
| Placebo | 0 of 1 |
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 |
|---|---|
| GWP42003-P | 1 of 1 |
| Placebo | 1 of 1 |
Most frequent serious adverse event terms
| Event term | Organ system | GWP42003-P | Placebo |
|---|---|---|---|
| Gastroenteritis viral | Infections and infestations | 1 of 1 | 0 of 1 |
Most frequent non-serious adverse event terms
| Event term | Organ system | GWP42003-P | Placebo |
|---|---|---|---|
| Irritability | Psychiatric disorders | 1 of 1 | 1 of 1 |
| Fatigue | General disorders | 1 of 1 | 0 of 1 |
| Tachycardia | Cardiac disorders | 1 of 1 | 0 of 1 |
| International normalised ratio increased | Investigations | 1 of 1 | 0 of 1 |
| Blood triglycerides | Investigations | 0 of 1 | 1 of 1 |
Serious events with the highest arm-level rate: gastroenteritis viral (100.0%).
The registry reports serious and other adverse-event counts separately for GWP42003-P and placebo. For serious adverse events, the record lists 1 participant at risk and 1 affected in the GWP42003-P group, and 1 at risk and 0 affected in the placebo group. For other adverse events, it lists 1 at risk and 1 affected in each group. Deaths are recorded as 0 in each group.
The registry also lists viral gastroenteritis among the top serious adverse-event terms at 100.0%. This is a registry entry for a term, not a comparative estimate of risk. The record does not provide further context for interpreting that percentage, such as a fuller event listing or analysis.
These counts are sparse. They describe the entries recorded in the registry but do not yield a precise estimate of how frequently adverse events would occur in a broader population. A difference in counts should not be treated as proof of a treatment-related difference. The record does not report a statistical comparison of adverse events, exposure-adjusted rates, or additional detail about severity, timing, or causal assessment. The safety information should therefore be read descriptively and in the context of the study’s termination and limited recorded enrollment.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a randomized, quadruple-masked Phase 3 study was planned to compare GWP42003-P oral solution with placebo in children and adolescents with EMAS. It identifies the intended primary endpoint as percent change from baseline in EMAS-associated seizure frequency over the 14-week treatment period. It also describes safety, tolerability, and a set of secondary outcomes that were part of the study’s stated aims.
What the record does not establish is whether GWP42003-P changed seizure frequency relative to placebo. No primary endpoint data were collected for analysis, and no efficacy estimates or uncertainty intervals are reported. The listed secondary outcomes likewise do not constitute results. The record therefore cannot support a conclusion about the direction, size, or precision of an efficacy difference.
The safety entries document adverse-event counts for the groups, including serious events, other events, and deaths. They are limited descriptive information and do not provide a precise comparison of safety between treatments. In particular, sparse counts cannot show how well those entries represent event frequencies beyond the recorded participants.
More generally, a terminated study with no analyzed primary endpoint leaves the clinical question unanswered by this registry record. That is different from evidence that a treatment is effective, and also different from evidence that it is ineffective. The record reports a study status and limited safety entries, but it does not report an analyzed efficacy result. Any planning illustration is a design calculation and should not be interpreted as observed treatment evidence or observed power.
13. Why This Trial Matters Statistically
This trial matters statistically because its design and intended endpoint are clearly identifiable, while the primary comparison is not available for analysis in the registry record. That distinction is important: a randomized, masked design can be suitable for reducing bias in a comparison, but design features alone do not supply outcome evidence. An interpretable treatment estimate still requires collected endpoint data, a defined analysis, and an account of its uncertainty.
The endpoint also illustrates a common challenge in clinical research. Seizure frequency is an event-count outcome, and such data may be variable and repeated within participants. In general, analysis choices should account for the outcome’s distribution and the relationship among repeated observations. The registry does not report those choices, so readers cannot assess the planned statistical treatment of these features.
The registry’s termination status and statement that no primary endpoint data were collected are central to interpretation. A study’s title, phase, and list of intended outcomes can describe its scientific question, but they do not establish an answer. The record also lists secondary measures and safety counts, yet neither substitutes for the missing primary comparison.
Finally, the distinction between planning calculations and observed evidence matters. Sample-size illustrations can help describe hypothetical study requirements under stated assumptions, but they are not a measure of the results or the power achieved by a terminated study. This record is a useful example of why statistical interpretation depends on the actual analysis and its uncertainty, not only on the intended design.
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 main limitation for interpreting this trial is that the registry states no data were collected for the primary endpoint because the study was terminated before it was analyzed. No primary efficacy estimate, treatment contrast, or confidence interval is reported. The reason for termination is not reported in the registry record.
The recorded enrollment is 3, but the registry does not explain participant flow, the number assigned to each group, treatment exposure, completion, or whether any participants contributed to outcomes other than the primary endpoint. The adverse-event entries list 1 participant at risk in each group, but the record does not reconcile those entries with the enrollment figure or explain the relevant exposure periods. No reconciliation should be inferred.
The record does not report detailed eligibility criteria, baseline seizure frequencies, data-collection procedures, outcome definitions beyond the endpoint title, or the statistical analysis plan. It also does not report missing-data methods, analysis populations, multiplicity procedures, interim analyses, or stopping rules. These omissions limit assessment of how the intended study would have produced and interpreted an estimate.
Although secondary outcomes are listed, their results are not reported. The safety information is limited to sparse counts and a listed serious-event term, without a reported comparative analysis or further context. These limitations mean the registry record can describe the intended design and the available entries, but cannot answer the primary efficacy question or characterize treatment effects precisely.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Efficacy and Safety of GWP42003-P Oral Solution in Children With Epilepsy With Myoclonic-atonic Seizures — NCT05288283.
- Registry record last updated 2025-02-03; status last verified 2025-01.
- Results first posted 2025-02-03.
- 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 NCT05288283, a randomized, quadruple-masked, parallel-group, placebo-controlled Phase 3 study of GWP42003-P oral solution in children and adolescents with epilepsy with myoclonic-atonic seizures. It lists enrollment of 3, a start date of 2022-10-31, a primary completion date of 2023-09-28, and a status of terminated.
The primary endpoint was percent change from baseline in EMAS-associated seizure frequency over the 14-week treatment period. The record states that no data were collected for this endpoint because the study was terminated before analysis. It lists secondary outcomes but reports no analyses. Safety entries include serious and other adverse events and deaths for the GWP42003-P and placebo groups.
The registry does not report why the study was terminated, detailed analysis methods, or comparative efficacy results. The posted record therefore describes the intended study question and limited safety information but does not establish a primary efficacy finding.