A Clinical Trial to Investigate the Safety and Tolerability, Efficacy, Pharmacokinetics, Pharmacodynamics and Immunogenicity of 2 Dose Regimens of ARGX-117 in Adults With Multifocal Motor Neuropathy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Clinical Trial to Investigate the Safety and Tolerability, Efficacy, Pharmacokinetics, Pharmacodynamics and Immunogenicity of 2 Dose Regimens of ARGX-117 in Adults With Multifocal Motor Neuropathy (NCT05225675), a randomized phase 2 study. The primary outcome is Number of Participants With AEs and SAEs.

2. Clinical Question

The trial asked whether two dose regimens of ARGX-117 could be evaluated for safety and efficacy against placebo in adults with multifocal motor neuropathy (MMN) who had previously been stabilized with intravenous immunoglobulin (IVIg). The registered primary outcome was the number of participants with adverse events (AEs) and serious adverse events (SAEs), assessed up to 80 weeks. That outcome describes how many participants experienced events; it does not, by itself, quantify event severity beyond the separate serious-event classification.

This framing matters because the registered primary outcome is a safety count, even though the trial title and summary also refer to efficacy and other biological measures. The registry lists additional outcomes, including time to first IVIg retreatment, time to relapse, and changes in motor-function measures. Their presence identifies other questions the trial intended to assess; it does not establish what those outcomes showed.

3. Trial Design

This was a phase 2, randomized, double-blinded, placebo-controlled, parallel-group, multicenter trial. The registry describes quadruple masking. Randomization assigns participants to groups by chance, while masking is intended to limit the influence of treatment knowledge on participants and other people involved in the trial. The record does not specify which roles were included in the quadruple masking.

The trial compared two ARGX-117 dose regimens with placebo. The interventions are described as intravenous administration, and the registry lists ARGX-117 Cohort 1, Placebo Cohort 1, ARGX-117 Cohort 2, and Placebo Cohort 2. The registered adverse-event counts give 18 participants at risk in each ARGX-117 cohort and 9 in each placebo cohort. The record does not report the dose amounts or the rationale for the cohort sizes.

Enrollment was 54. The registry lists the study as completed, with a start date of 2022-03-31 and a primary completion date of 2024-06-04. The primary outcome timeframe was up to 80 weeks. These dates and the timeframe describe the registered study record; they do not establish that every participant had the same duration of observation.

Participants had MMN and had previously been stabilized with IVIg, according to the brief study description. The secondary outcomes include time-to-event measures, motor-function sum scores, and measures based on daily grip strength. The record lists 21 outcome measures and 2 analyses, but does not report the full analysis plan or which populations were used for each analysis. The enrollment total should therefore be understood as the number enrolled, not automatically as the denominator for every endpoint.

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

Reasons for not completing this period:

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.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With AEs and SAEs, measured over Up to 80 weeks.

The primary endpoint is the number of participants with AEs and SAEs, with a timeframe of up to 80 weeks. An AE is an adverse event; an SAE is a serious adverse event. The endpoint is expressed as a count of participants with events, rather than as a measure of event duration, total event episodes, or change in a clinical score.

Counting participants with AEs and SAEs is a way to describe safety experience during a trial. Reporting serious events separately helps distinguish events classified as serious from the broader group of adverse events. However, a participant count does not reveal how many total events occurred if one person experienced more than one event, nor does it explain each event’s timing, duration, outcome, or relationship to treatment. Those details are not reported in the registry record presented for this outcome.

The endpoint is not an efficacy measure. The registry names efficacy as a trial objective and lists secondary outcomes involving relapse, IVIg retreatment, motor-function scores, and grip strength. Results for those measures are not reported in the registry record. The safety counts therefore cannot answer whether a dose regimen changed motor function or time to relapse.

For interpretation, the cohort denominators matter: the registry reports 18 participants at risk in each ARGX-117 cohort and 9 in each placebo cohort. Counts should be read within their respective cohorts rather than treated as if all groups had identical sizes. The record does not provide an adjusted comparison or a confidence interval for this primary endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The central numerical outcome is a participant count. For each cohort, the registry gives the number at risk and the number of participants with serious and other adverse events. A count is directly interpretable as the number of people recorded with the event category, but the count alone does not describe the precision of a comparison. It also does not indicate whether a participant experienced one event or several.

What does a cohort count tell us?

A cohort count pairs an observed number of participants with an at-risk denominator. Here, the serious-event counts are 2 among 18 for ARGX-117 Cohort 1, and 0 among 9, 0 among 18, and 0 among 9 in the other listed cohorts. For other adverse events, the corresponding counts are 14 among 18, 5 among 9, 14 among 18, and 6 among 9. Keeping the cohorts distinct preserves the group structure reported in the registry. It avoids assuming that the two active-treatment cohorts or the two placebo cohorts can be pooled.

General statistical explanation: an observed count is subject to sampling variability. A confidence interval, when calculated using a stated method, describes a range of values compatible with the data and method; it is not a guarantee that the true value lies in that range. No confidence interval for the primary endpoint is reported in the registry record. The counts should therefore be read as descriptive results rather than as precise estimates of comparative effects.

Why separate serious from other adverse events?

Serious adverse events are a distinct safety category from other adverse events. Reporting them separately makes the seriousness classification visible, while the broader adverse-event counts describe participants with events outside that serious-event count. These categories do not convey the complete clinical context of an event. The record does not report details such as timing, duration, outcome, or treatment attribution for the cohort counts. The two serious-event terms listed by the registry are acute coronary syndrome and pneumonia, each at 5.6%; the record does not specify a denominator or cohort attribution for those percentages in the listing.

What can randomization and masking contribute?

General statistical explanation: random assignment aims to make treatment groups comparable, on average, with respect to factors that could affect outcomes. In a small trial, chance differences in participant characteristics can still occur. Masking is intended to reduce the chance that knowledge of assignment influences care, event reporting, or outcome assessment. The registry describes the trial as randomized and quadruple-masked, but does not report the exact masking roles or a balance assessment for participant characteristics. These design features support careful comparison; they do not substitute for the numerical analysis.

The parallel-group design means participants are assigned to a group and followed in that group, rather than crossing between treatments as part of the stated model. The trial is described as placebo-controlled and multicenter. The registry does not provide additional center-level results or a detailed account of how center effects were handled analytically.

How should planning calculations be read?

The stated sample-size illustrations are planning calculations based on an observed effect, not the trial’s own design justification. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect defined as a stated fraction of the observed effect. For time-to-event outcomes, the illustration uses a total event count; for other outcomes, it describes participants per arm. Such illustrations explore planning under assumptions. They are not observed power and do not show that the completed trial had a particular probability of detecting an effect. The registry record does not report the original sample-size justification.

General statistical explanation: over-dispersion occurs when count variability is greater than expected under a simple model for counts. It can make model-based uncertainty too small if the analysis assumes less variability than the data contain. The primary outcome is reported as participants with events, and no dispersion parameter or count-model analysis is reported in the registry record. No claim about over-dispersion or a specific model can therefore be made for this trial.

There are 21 outcome measures and 2 analyses listed in the record. This indicates that results and analysis questions extend beyond the primary safety count, but does not reveal the statistical tests, model specifications, covariate adjustments, or uncertainty measures used. Those details are not reported in the registry record. Without them, the reader cannot reconstruct an inferential analysis from the cohort counts alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 21 outcome measures and 2 analyses. Multiple outcomes can create multiple opportunities to identify a result that appears notable by chance. General statistical explanation: multiplicity procedures control or describe that issue by specifying how results across several tests are interpreted. The registry record does not report whether a multiplicity adjustment was used, which outcomes were included in any adjustment, or how the two listed analyses relate to the outcomes. No conclusion about control of multiplicity can be drawn.

The record names the primary outcome as the number of participants with AEs and SAEs, and gives a timeframe of up to 80 weeks. It does not report a statistical analysis plan defining the primary contrast, the statistical test or model, or the handling of multiple outcome categories. The record also does not report the analysis populations, such as whether analyses were based on all randomized participants or another defined set.

Missing-data methods are not reported in the registry record. The outcome timeframe does not establish that all participants were observed for the same length of time, and the enrollment total is not necessarily the denominator for every result. The record does not state how incomplete follow-up, missing assessments, or withdrawals were handled. For time-to-event outcomes among the secondary measures, censoring rules and analysis details are also not reported.

These gaps limit interpretation of the posted counts. The reported cohort denominators make the event counts readable, but do not explain how participants with incomplete follow-up were treated or whether the counts reflect a prespecified analysis population. No imputation, sensitivity analysis, or multiplicity method should be assumed.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: acute coronary syndrome (5.6%), pneumonia (5.6%).

The registry reports serious adverse events for each cohort as follows: 2 participants among 18 at risk in ARGX-117 Cohort 1, and 0 among 9 in Placebo Cohort 1, 0 among 18 in ARGX-117 Cohort 2, and 0 among 9 in Placebo Cohort 2. It reports no deaths in any cohort. These are observed participant counts, not total event counts or estimates adjusted for follow-up duration.

Acute coronary syndrome and pneumonia are each listed among the top serious-event terms at 5.6%. The registry does not state the denominator for these percentages or identify a cohort for each term in this listing. They should therefore be read as registry-reported terms and percentages, not as cohort-specific comparative rates.

General statistical explanation: zero observed events do not demonstrate that an event cannot occur. With limited numbers of participants, uncommon events may not be observed, and estimates based on small groups can be imprecise. Conversely, an observed event does not establish that the intervention caused it. The counts do not provide event attribution, timing, duration, or outcome, and the registry record does not report an adjusted statistical comparison of serious adverse events.

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

The results establish that the registry recorded adverse-event counts in four cohorts, with the denominators and serious-event counts stated separately. They also establish that the registry reported no deaths in those cohorts and listed acute coronary syndrome and pneumonia among the serious-event terms, each at 5.6%. These are descriptions of the posted safety data, not causal conclusions.

The counts do not show whether ARGX-117 changed the probability of an adverse event relative to placebo. Such a conclusion would require an appropriate comparison and an assessment of uncertainty. No comparative estimate or confidence interval for the primary endpoint is reported in the registry record. Differences in observed counts alone cannot establish that one group’s underlying risk was higher or lower.

The safety endpoint does not answer the trial’s efficacy questions. The registry lists outcomes involving IVIg retreatment, relapse, motor-function scores, and grip strength, but their results are not reported in the registry record. It is therefore not possible to draw an efficacy conclusion from the adverse-event counts.

The record identifies a randomized, quadruple-masked phase 2 design and an enrollment of 54. Those features provide context for the study, but they do not resolve limitations in outcome reporting or replace an analysis plan. The registry does not report the original sample-size justification, missing-data methods, analysis populations, or multiplicity procedures. The planning illustrations described in the record are not observed power calculations.

Accordingly, the most defensible interpretation is narrow: the registry provides descriptive safety counts for the listed cohorts and timeframe. It does not, in the reported information, establish a comparative safety effect, explain the cause of events, or report whether the efficacy objectives were met.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of the distinction between a study’s broad objectives and its registered primary endpoint. The trial description includes safety, efficacy, pharmacokinetics, pharmacodynamics, and immunogenicity, while the stated primary outcome is the number of participants with AEs and SAEs. A reader should not treat those different aims as interchangeable: a safety count cannot stand in for an efficacy result.

The four-cohort reporting also makes denominators important. The ARGX-117 cohorts each report 18 participants at risk, while each placebo cohort reports 9. Keeping those groups separate makes the registry’s structure visible. It also discourages a casual comparison that might pool cohorts or ignore differences in group size without a stated analysis plan.

General statistical explanation: randomized, masked trials are designed to support fair comparisons by reducing allocation and assessment biases. But design labels alone do not communicate the uncertainty in observed results. Event counts, uncertainty estimates, analysis populations, and prespecified methods all matter when interpreting comparisons. In this record, cohort counts are available, but comparative estimates and several analysis details are not reported.

The registry lists 21 outcome measures and 2 analyses. That breadth makes multiplicity and selective emphasis relevant statistical considerations, although the record does not report whether or how multiplicity was addressed. The same caution applies to missing data and sample-size planning: absent methods should not be filled in by assumption.

The trial therefore matters statistically not because the available counts settle a treatment question, but because they show what can and cannot be learned from registry reporting. Descriptive safety data are useful, while comparative interpretation requires fuller results and methods.

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 posted safety information is limited to cohort counts and at-risk denominators. The registry record does not report a confidence interval, statistical test, adjusted comparison, or detailed analysis model for the primary endpoint. This prevents assessment of the precision of a difference between ARGX-117 and placebo using the registry information.

The dose amounts and schedule details for the two ARGX-117 regimens are not reported in the registry record. The relationship between the two cohorts, including whether they were intended to be pooled for any analysis, is not specified. The record also does not describe the roles covered by quadruple masking.

The serious-event terms acute coronary syndrome and pneumonia are each listed at 5.6%, but their denominators and cohort assignments are not reported in that listing. Event timing, duration, outcomes, and treatment attribution are also not reported alongside the cohort counts. The absence of deaths in the reported cohorts is an observed result and does not establish that the risk of death is zero.

The registry does not report results for the listed efficacy outcomes, including relapse, IVIg retreatment, motor-function measures, and grip-strength measures. It also does not report the analysis populations, missing-data methods, multiplicity approach, or original sample-size justification. The sample-size illustrations described in the record are planning scenarios, not a substitute for those design details and not observed power.

Finally, enrollment of 54 does not mean that every endpoint used all enrolled participants or that follow-up was complete for every participant. The record gives an outcome timeframe of up to 80 weeks but does not report participant-level follow-up duration or handling of incomplete observations. These limitations constrain both safety comparisons and broader conclusions about trial objectives.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Clinical Trial to Investigate the Safety and Tolerability, Efficacy, Pharmacokinetics, Pharmacodynamics and Immunogenicity of 2 Dose Regimens of ARGX-117 in Adults With Multifocal Motor Neuropathy — NCT05225675.
• Registry record last updated 2026-05-08; status last verified 2026-04.
• Results first posted 2026-05-08.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT05225675 is a completed phase 2, randomized, quadruple-masked, placebo-controlled, parallel-group, multicenter trial in adults with multifocal motor neuropathy previously stabilized with IVIg. Enrollment was 54. The registry lists two intravenous ARGX-117 cohorts and two intravenous placebo cohorts.

The primary outcome is the number of participants with AEs and SAEs up to 80 weeks. Serious adverse events were reported in 2 of 18 participants in ARGX-117 Cohort 1 and in none of the other three cohorts. Other adverse events were reported in 14 of 18 participants in each ARGX-117 cohort, 5 of 9 in Placebo Cohort 1, and 6 of 9 in Placebo Cohort 2. No deaths were reported. Acute coronary syndrome and pneumonia were each listed at 5.6% among serious-event terms; the listing does not specify their cohort attribution.

The registry lists efficacy and other outcomes, but their results and the detailed statistical analysis methods are not reported in the registry record. The available counts are descriptive and do not establish comparative efficacy or a causal safety effect.