A Study of Single and Multiple SC Doses of ALXN1830 in Healthy Adult Participants: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Single and Multiple SC Doses of ALXN1830 in Healthy Adult Participants (NCT05254613), a randomized phase 1 study. The primary outcome is Number of Participants With Treatment Emergent Adverse Events (TEAEs).

2. Clinical Question

3. Trial Design

This was a Phase 1, randomized, double-blind, placebo-controlled, parallel study of single and multiple subcutaneous doses of ALXN1830 in healthy participants. The record lists enrollment of 12 and identifies the study status as terminated. The study start is listed as 2019-11-12, and primary completion as 2021-01-22. The reason for termination is not reported in the registry record.

The listed cohort descriptions cover seven dose schedules. Cohorts 1, 2, and 3 received a single dose of ALXN1830 or placebo at 750 mg, 1500 mg, or 2250 mg, respectively. Cohorts 4 through 7 received multiple doses: 300 mg twice weekly for 8 doses total, 750 mg once weekly for 12 doses total, and 1500 mg or 2250 mg once weekly for 4 doses total. These descriptions indicate that both single-dose and repeated-dose regimens were included; they do not establish the number assigned to each cohort or the detailed sequence of dose escalation.

The posted safety groups are labeled ALXN1830 750 mg, ALXN1830 1250 mg, and placebo. The 1250 mg safety-group label does not match the 1500 mg dose listed in the cohort descriptions. The registry record does not clarify this difference, so the group label and cohort schedule should not be treated as interchangeable without further documentation.

The primary endpoint concerns treatment-emergent adverse events over the stated timeframe, rather than a clinical efficacy outcome. Secondary outcomes include serum concentration, change in IgG levels, and counts of participants with positive anti-drug antibodies and neutralizing antibodies. Numerical results for those secondary outcomes 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: Due to a lack of participant availability caused by the COVID-19 pandemic, the study was terminated on 22 January 2021 after completion of the ALXN1830 subcutaneous 750 milligrams (mg) dose or placebo groups and partial enrollment of the ALXN1830 subcutaneous 1250 mg dose or placebo groups.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The safety population consisted of all participants who received at least 1 dose of study drug.

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: The safety population consisted of all participants who received at least 1 dose of study drug.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Treatment Emergent Adverse Events (TEAEs), measured over Baseline up to Day 64.

The primary endpoint is the number of participants with treatment-emergent adverse events, with the assessment timeframe extending from baseline up to Day 64. A treatment-emergent adverse event is an adverse event that commences after study drug administration begins. An adverse event is defined as an untoward medical occurrence temporally associated with study drug use, regardless of whether it is considered related to the drug.

This endpoint is used to describe the occurrence of adverse events during exposure in the study population. Counting participants with at least one event gives a participant-level summary; it is not the same as counting every event, because a participant may experience more than one adverse event. The posted primary endpoint is a count outcome. The registry record does not provide a statistical comparison, confidence interval, or detailed event-level breakdown for this endpoint.

Seriousness is defined separately from whether an event is considered related to treatment. An event is serious if, in the investigator’s or sponsor’s view, it results in death, is life-threatening, requires inpatient hospitalization or prolongs existing hospitalization, causes persistent or significant incapacity or substantial disruption of normal life functions, or is a congenital anomaly or birth defect. The record says summaries of serious and other nonserious adverse events, regardless of causality, are located in the adverse-events material. This distinction matters when interpreting the separate counts for serious events and other events.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized, double-blind, parallel-group design with placebo control. Randomization is intended, in general, to reduce systematic differences between groups at assignment. Blinding is intended, in general, to limit the influence of knowledge about assigned treatment on participant or investigator behavior and on outcome assessment. These design features do not guarantee that groups will be comparable in a small study, and the record does not describe the randomization procedure, concealment method, or who was blinded.

What does the primary count represent?

The primary outcome counts participants with treatment-emergent adverse events. A participant-level count records whether a participant experienced an event in the defined period; it does not give the total number of events or their duration. The registry defines the period as baseline up to Day 64 and defines treatment-emergent events by their onset after study drug administration begins. The interpretation depends on consistent event identification and follow-up, but details of event collection and adjudication are not reported in the registry record.

The endpoint is binary at the participant level: a participant either meets the event definition or does not. General statistical methods for binary outcomes can compare the proportion of participants with an event across groups. Such comparisons may be expressed as differences or ratios, and confidence intervals can describe the precision of an estimate. A confidence interval is a range of values compatible with the data under the method’s assumptions; it is not a guarantee that the true value falls within that particular range. No such comparative estimates or confidence intervals are reported for this primary outcome in the registry record.

Why are descriptive counts limited?

Counts alone are useful for showing how many participants were affected in each posted group, but they do not convey the full uncertainty around a comparison. In small groups, a change in the outcome status of a single participant can materially alter the observed pattern. General statistical inference accounts for sample size and outcome variability when estimating uncertainty. The registry record lists 6 participants at risk for ALXN1830 750 mg, 3 for ALXN1830 1250 mg, and 3 for placebo. It does not report an inferential analysis that uses these counts to compare groups.

A p-value, when used, assesses how compatible observed data are with a specified null hypothesis under a statistical model. It does not measure the size or clinical importance of an effect, and it does not establish causation. No p-value or test result is reported for the primary endpoint. The absence of a reported test means the posted counts should not be recast as a finding of statistical significance or non-significance.

What is the role of sample-size planning?

The registry record includes a general planning framework based on a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The framework describes planning illustrations in relation to a stated fraction of an observed effect. For non-time-to-event outcomes, the stated convention is participants per arm; time-to-event examples use a total event count. These are planning assumptions, not a description of the trial’s actual design justification. The record does not report a sample-size justification for this trial, and the planning framework must not be interpreted as observed power or as evidence that the study was adequately powered.

Observed power is generally not a useful substitute for an estimate and its uncertainty after a study has been completed. A planning calculation instead asks what sample size would be needed under specified assumptions. The registry record does not report the actual assumptions for a trial-specific calculation, a target effect, or a trial-specific sample-size result. No sample-size conclusion can therefore be drawn from the framework alone.

How should multiple outcomes be considered?

The registry lists secondary outcomes for pharmacokinetics, IgG change, and immunogenicity, in addition to the primary adverse-event count. When several outcomes are tested, general statistical practice considers multiplicity: repeated testing can increase the chance of at least one apparently unusual result under a collection of null hypotheses. Approaches may include adjustment or a prespecified hierarchy, but the registry record does not report a multiplicity strategy. Because no analyses are reported, it is not possible to determine whether any adjustment was used or whether secondary outcomes were tested inferentially.

Over-dispersion is a general concern when count data vary more than a chosen model expects. It can make standard errors too small if the model does not allow for the extra variability. The primary endpoint is a participant count rather than a reported event-frequency model, and the registry provides no model specification or dispersion estimate. Thus, no claim about over-dispersion or a fitted model can be made for this study.

The record reports 0 analyses. No analysis population beyond the defined safety population is described for the primary endpoint, and no missing-data method, covariate adjustment, interim analysis, or statistical analysis plan is reported. These omissions limit assessment of how the posted outcomes were handled and how any inferential conclusions would have been drawn.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists multiple outcomes: the primary count of participants with treatment-emergent adverse events, plus outcomes covering ALXN1830 serum concentration, IgG change, anti-drug antibodies, and neutralizing antibodies. The numerical results for the secondary outcomes are not reported in the registry record. The record reports 0 analyses, and it does not describe a multiplicity procedure, testing hierarchy, or primary-versus-secondary testing strategy. In general, multiple statistical tests can increase the chance of a false-positive finding across a family of tests, so a prespecified approach is important when inferential claims are made. No such approach can be established from this record.

The primary endpoint’s safety population is defined as all participants who received at least 1 dose of study drug. The adverse-event group counts are reported, but the record does not describe the number randomized, the number completing follow-up, or how participants with incomplete follow-up were handled. It does not report a missing-data method or say whether outcome data were complete through Day 64.

The record does not describe an intention-to-treat population, a per-protocol population, or another analysis population for inferential testing. It also does not report an interim-analysis plan or a statistical analysis plan. These details are not reported in the registry record; their absence should not be filled by assumptions about standard practice. Without those details and without reported analyses, it is not possible to assess the impact of missing outcomes, deviations, or multiplicity on comparative conclusions.

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 0% reporting threshold.

Most frequent non-serious adverse event terms

The posted safety summary lists serious adverse-event counts of 0 for ALXN1830 750 mg, 0 for ALXN1830 1250 mg, and 0 for placebo. The corresponding numbers at risk are 6, 3, and 3. Deaths are listed as 0 in each group. These are the reported participant counts; they are not estimates of future risk or evidence that serious events are impossible.

For other adverse events, the counts are 5 in the ALXN1830 750 mg group, 3 in the ALXN1830 1250 mg group, and 3 in the placebo group. The registry describes these as nonserious adverse events regardless of causality. The counts do not establish whether events were related to study drug. They also do not indicate how many separate events occurred, because the endpoint counts participants rather than event episodes.

The serious-event terms list is empty. The record does not provide detailed terms for the other adverse events in the information summarized. A serious event is defined by specified outcomes, including death, life-threatening events, inpatient hospitalization or its prolongation, persistent or significant incapacity, substantial disruption of normal life functions, or congenital anomaly or birth defect. The posted groups are small, so zero observed serious events should be read as a description of this study’s recorded experience, not as a precise estimate of the frequency of uncommon events.

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

The posted results establish that the registry reports participant counts for treatment-emergent adverse events in three safety groups and records no serious adverse events or deaths in those groups. They also show that other, nonserious adverse events were recorded among participants in each group. These are descriptive findings for the study population and follow-up period stated in the record.

The counts do not establish a causal effect of ALXN1830. Adverse events are defined as occurrences temporally associated with study drug use, whether or not considered related to the drug. The group counts alone cannot identify whether an event was caused by treatment, nor do they account for differences in participant characteristics, exposure, or follow-up. The registry does not report a formal comparison, estimate of uncertainty, or p-value for the primary endpoint.

The results also do not establish that the groups have equal rates of adverse events. Similar-looking counts in small groups can be compatible with a range of underlying values, and a lack of a reported inferential test is not evidence of equivalence. Conversely, an observed count in one group should not be interpreted as proof of harm. The record gives no detailed account of adverse-event types, severity beyond the serious-versus-other distinction, or event timing beyond the primary endpoint timeframe.

These findings are limited to the healthy participants and dose schedules described in this Phase 1 study. They do not establish outcomes in other populations or for regimens not represented in the record. The secondary outcomes are named, but their numerical findings are not reported. The study’s terminated status is listed, but the reason and its implications for completeness are not reported in the registry record. The result therefore supports a narrow reading of posted safety counts, not a broad clinical conclusion.

13. Why This Trial Matters Statistically

This trial matters statistically because its design combines several dose schedules with a placebo comparator while enrolling 12 healthy participants. Phase 1 studies can describe early safety observations and other measured outcomes under specified exposure conditions. In a small study, however, descriptive participant counts carry substantial uncertainty, particularly for uncommon events. The record reports counts but no statistical comparison or confidence interval, so interpretation must remain descriptive.

The distinction between participant counts and event counts is especially important for adverse-event reporting. The primary outcome counts participants with at least one treatment-emergent event, while the safety summary also separates serious from other events. Those summaries answer different descriptive questions: whether participants experienced events and whether events met the seriousness definition. Neither count by itself explains causality or captures every aspect of event burden.

The study also highlights the importance of consistent treatment labels. The cohort descriptions list a 1500 mg schedule, while one posted safety group is labeled 1250 mg. The registry record does not reconcile the difference. Clear alignment between planned cohorts, assigned treatment, and reported analysis groups is necessary for readers to interpret dose-specific findings.

Finally, a registry record can identify outcomes without supplying numerical results or analytical details. Here, secondary outcome names are listed, but numerical results and inferential analyses are not reported. The record also does not state a trial-specific sample-size justification, missing-data approach, or multiplicity strategy. These gaps matter because statistical interpretation depends not only on observed counts, but also on how outcomes were defined, collected, analyzed, and reported.

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 groups are small: the registry lists 6 participants at risk in the ALXN1830 750 mg group, 3 in the ALXN1830 1250 mg group, and 3 in the placebo group. Such counts provide limited precision, particularly for uncommon outcomes. The record does not provide confidence intervals or another measure of uncertainty for the adverse-event counts.

The registry lists total enrollment as 12, but does not report how many participants were randomized, how many completed follow-up, or whether all enrolled participants received at least 1 dose. The safety population is defined by receipt of at least 1 dose. A missing-data method and completeness of adverse-event follow-up are not reported in the registry record.

There is a labeling inconsistency: cohort descriptions include a 1500 mg dose, while the posted safety group is labeled ALXN1830 1250 mg. The registry record does not explain this difference. The record also does not describe the allocation ratio, randomization method, blinding procedures, or the reason the study was terminated.

Although secondary outcomes are listed, their numerical results are not reported. The record reports no analyses and does not describe a statistical analysis plan, multiplicity handling, covariate adjustment, or interim analyses. It also does not provide detailed nonserious adverse-event terms in the summarized information. These limitations restrict interpretation to the posted descriptive counts and prevent assessment of comparative uncertainty or the completeness of the full outcome profile.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Study of Single and Multiple SC Doses of ALXN1830 in Healthy Adult Participants — NCT05254613.
• Registry record last updated 2024-03-22; status last verified 2024-03.
• Results first posted 2024-03-22.
• 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

NCT05254613 is a randomized, double-blind, placebo-controlled, parallel Phase 1 study of single and multiple subcutaneous doses of ALXN1830 in healthy participants. The registry lists enrollment of 12, study status as terminated, a start date of 2019-11-12, and primary completion on 2021-01-22. The reason for termination is not reported in the registry record.

The primary endpoint is the number of participants with treatment-emergent adverse events from baseline up to Day 64. The posted safety groups report serious adverse-event counts of 0 in each group and other adverse-event counts of 5, 3, and 3 for ALXN1830 750 mg, ALXN1830 1250 mg, and placebo, respectively. The record reports 0 analyses. Numerical findings for the listed secondary outcomes, inferential comparisons, missing-data methods, and a trial-specific sample-size justification are not reported in the registry record.