Anti-TSLP (AMG 157) Plus Antigen-Specific Immunotherapy for Induction of Tolerance in Individuals With Cat Allergy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Anti-TSLP (AMG 157) Plus Antigen-Specific Immunotherapy for Induction of Tolerance in Individuals With Cat Allergy (NCT02237196), a randomized phase 1, phase 2 study. The primary outcome is Total Nasal Symptom Score (TNSS) Area Under the Curve (AUC).

2. Clinical Question

This is a question about the measured symptom response at a specified challenge assessment, not a direct measure of lasting tolerance in everyday settings. The trial description states an objective of determining whether one year of combined immunotherapy and AMG 157 can induce tolerance to cat allergen. The posted primary endpoint, however, is the Total Nasal Symptom Score area under the curve from 0 to 1 hour of the Nasal Allergen Challenge at Week 104.

The endpoint is a continuous score, with higher values indicating more severe nasal symptoms. The primary analysis contrasted the AMG 157 plus cat immunotherapy group with the group receiving cat immunotherapy plus AMG 157 placebo. The posted results therefore address whether the additional AMG 157 component was associated with a difference in this score in that comparison. They do not, by themselves, establish a broad conclusion about every outcome or every possible meaning of tolerance.

3. Trial Design

The registry describes a randomized, triple-masked, parallel-group trial in Phase 1 and Phase 2. Enrollment was 121, and the study status is completed. The four assigned regimens were AMG 157 plus cat immunotherapy; AMG 157 placebo plus cat immunotherapy; AMG 157 plus cat immunotherapy placebo; and placebo for both treatments. The intervention descriptions specify administration every four weeks for AMG 157 or its placebo, and weekly for cat immunotherapy or its placebo.

The primary reported comparison used the first two groups. This is the comparison that holds cat immunotherapy in common while contrasting AMG 157 with its placebo. The other two groups provide the remaining combinations of active treatment and placebo in the parallel design, but the posted primary contrast does not compare them with one another.

The study started on 2015-03-03 and primary completion was 2019-03-04. These dates describe the registry record; they do not supply details about recruitment timing, follow-up completeness, or the duration of each participant’s observation. Those details are not reported in the registry record.

Randomization is intended to create groups that are comparable on average, while masking can reduce the influence of knowledge of assigned treatment on participant reports, care, and assessment. These are general design principles, not proof that every potential source of bias was eliminated. The registry identifies the trial as triple-masked but does not state in the posted results which specific roles were masked or how masking was maintained.

The primary outcome analysis used a longitudinal repeated measures model in the intent-to-treat sample. The record also lists secondary assessments involving skin responses, nasal symptoms, and nasal inspiratory flow. A detailed account of the allocation procedure, masking procedures, recruitment targets, or sample-size justification is 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intent-to-treat

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 Total Nasal Symptom Score (TNSS) Area Under the Curve (AUC), measured over 0 to 1 hour of the NAC at Week 104.

The primary endpoint is the Total Nasal Symptom Score area under the curve, measured from 0 to 1 hour of the Nasal Allergen Challenge at Week 104. The score combines four participant-rated nasal symptom subscales: congestion and blockade, rhinorrhea, itching, and sneezing. Each subscale ranges from 0 to 3, with higher ratings representing more severe symptoms. The combined TNSS ranges from 0-12. The unit is Total Nasal Symptom Score * Hour.

The trapezoidal rule was used to calculate the area under the curve. In general, an area-under-the-curve summary combines repeated measurements over a specified interval, reflecting both the level of a measure and how it changes during that interval. It can provide a single summary for comparing symptom response across the challenge period. Here, the interval is the first hour after cat allergen challenge, so the endpoint is specifically a short-term response under the challenge assessment rather than a direct record of symptoms in day-to-day life.

The endpoint was analyzed as a continuous measure, and the reported group summaries are least squares means with 95% confidence intervals. The use of a model-based mean allows the primary contrast to account for the covariates and repeated observations described in the registry record. Interpretation should remain tied to this score, assessment, and timepoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary analysis used a longitudinal repeated measures model. In general, repeated measures models analyze observations collected over time while accounting for the relationship among measurements from the same participant. Rather than treating every observation as independent, the model uses a specified structure to estimate treatment patterns across time and to form a contrast at the target assessment. The registry does not report the model’s covariance structure or the details of how incomplete repeated observations were handled.

What does the adjusted contrast represent?

The primary endpoint description says the analysis included fixed effects for treatment, time, and the treatment-by-time interaction. It also included covariates for site, baseline TNSS area under the curve, and baseline cat exposure categorized as low versus high. In general, adjustment incorporates these measured factors into the model when estimating the treatment contrast. A fixed effect represents a modeled contribution associated with a specified factor; the interaction allows the modeled treatment difference to vary across time.

The primary endpoint was assessed at Week 104 using a contrast in least squares means between AMG 157 plus cat immunotherapy and AMG 157 placebo plus cat immunotherapy. A least squares mean is a model-based mean, adjusted according to the variables in the analysis. It is not necessarily the same as a simple arithmetic average of observed participant scores. The contrast summarizes the modeled difference between those adjusted means at the assessment of interest.

How should the confidence interval be read?

A confidence interval expresses uncertainty around an estimated quantity under the assumptions of the statistical model and analysis. In general, narrower intervals indicate greater precision, while wider intervals indicate less precision. The 95% confidence interval for the reported net mean difference extends from -1.51 to 0.49. Because that interval includes zero, the data do not rule out no difference at the conventional two-sided 5% level. The interval also includes estimates in either direction, so the point estimate should not be treated as a precise estimate of the true difference.

The confidence intervals around the separate least squares means describe uncertainty in each model-based group mean. They should not be used as a substitute for the confidence interval of the between-group contrast. The uncertainty of a difference depends on the joint model estimates, including how they covary; comparing whether separate intervals overlap is not the formal test of the treatment contrast.

What does the p-value contribute?

The reported p-value is 0.314 for the superiority comparison. In general, a p-value evaluates how unusual results at least as incompatible with a specified null hypothesis would be if that hypothesis and the analysis assumptions were true. It is not an effect-size measure, and it does not give the probability that the null hypothesis is correct. The estimate and confidence interval are needed to assess direction, plausible magnitude, and precision. A p-value above a conventional threshold does not establish equivalence or absence of an effect.

Why can over-dispersion matter?

Over-dispersion is a general concern for outcomes whose variability exceeds what a statistical model expects. When a model understates variability, standard errors can be too small and confidence intervals can be too narrow, making statistical evidence appear stronger than it is. The primary endpoint is a continuous symptom-score area under the curve, and the posted analysis reports least squares means and a confidence interval. The registry record does not describe an over-dispersion assessment or identify over-dispersion as a feature of this analysis. The concept is relevant as a general modeling issue, not as a reported finding in this trial.

What does the intent-to-treat population mean?

The primary outcome is identified as analyzed in the intent-to-treat population. In general, an intent-to-treat approach analyzes participants according to their randomized group, preserving the basis of the randomized comparison even if treatment received differs from assignment. The registry record does not give a participant flow account or clarify how all post-randomization events and unavailable outcome measurements were treated. The arm counts appearing with outcome summaries should not, on their own, be read as a complete description of missingness or analysis exclusions.

How should the recalculation and planning illustrations be understood?

Any simple recalculation from posted summary statistics is unadjusted and does not reproduce a longitudinal model that includes covariates and repeated observations. The sponsor’s reported analysis is the relevant analysis for the registered primary comparison; the registry does not flag a discrepancy between it and the posted results. Planning illustrations based on an observed effect are not observed power, and they do not show the probability that the completed trial detected an effect. The stated planning assumptions include a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects defined as fractions of the observed effect. Such illustrations are hypothetical planning exercises, not additional trial outcomes.

10. Analyses Reported by the Sponsor

The sponsor-reported analysis is a longitudinal repeated measures analysis of the primary comparison, with a net mean difference of -0.51, a 95% confidence interval from -1.51 to 0.49, and p = 0.314. It compares AMG 157 plus cat immunotherapy with AMG 157 placebo plus cat immunotherapy at the primary assessment, using the model described in the registry record.

A recalculation from posted summary statistics, when presented, is a simple unadjusted calculation. It cannot reproduce the sponsor’s model-based contrast because it does not incorporate the repeated-measures structure, treatment-by-time interaction, site, baseline TNSS area under the curve, or baseline cat exposure. These calculations answer related but not identical statistical questions. The registry does not indicate a discrepancy, and its reported sponsor analysis remains the interpretation to prioritize for the registered primary endpoint.

The sponsor’s p-value and confidence interval should be read together. The estimate is negative, but its interval includes zero, and the p-value is 0.314. This describes uncertainty around the model-based comparison; it does not prove no effect, establish equivalence, or show that the observed point estimate is the true effect. Any planning illustration based on the observed estimate is a hypothetical design aid, not an observed result or a measure of the trial’s achieved power.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and eight secondary outcomes. The secondary measures include skin prick test endpoint titration, early and late skin responses to intradermal testing, early and late total nasal symptom responses, and early and late peak nasal inspiratory flow measures. Testing several outcomes can increase the chance that at least one result appears statistically unusual by chance. In general, multiplicity procedures can control that risk, but they may also change the interpretation of individual p-values and intervals.

A multiplicity adjustment, a prespecified hierarchy among secondary outcomes, and a family-wise error strategy are not reported in the registry record. The record reports one analysis for the primary continuous outcome. It does not provide a basis for assuming that the secondary outcomes were adjusted, that they were all tested as confirmatory hypotheses, or that their results should be treated as independent confirmation. Conclusions should therefore remain tied to the specific endpoint and comparison being discussed.

The primary analysis population is identified as intent-to-treat, and the endpoint description gives the repeated measures model and included covariates. However, the registry does not report a detailed account of missing outcome data, reasons for missingness, imputation methods, sensitivity analyses, or how participants with incomplete repeated measurements contributed to the model. Those omissions limit assessment of how robust the estimate may be to missing-data assumptions.

The record also does not report an interim analysis plan, stopping rules, or a detailed protocol for handling deviations from assigned treatment. These details should not be inferred from the randomized and masked design. The total enrollment is 121, while the primary outcome summaries list group counts of 32, 31, 30, and 28. These counts describe the posted summaries but do not explain participant flow, exclusions, or the availability of each measurement. The registry record does not report those explanations.

The record’s stated planning assumptions describe hypothetical calculations based on the observed effect. They are not evidence of observed power and do not replace a reported sample-size justification. A formal sample-size rationale, including its target effect and allowance for incomplete data, is not reported in the registry record.

12. 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: infusion related reaction (3.2%), breast cancer (3.2%), hyperventilation (3.2%), pneumomediastinum (3.2%), cerebral infarction (3.1%).

The posted serious adverse event figures list 1 affected participant among 32 at risk in the AMG 157 plus cat immunotherapy group, 3 among 31 at risk in the AMG 157 placebo plus cat immunotherapy group, and 0 among 29 and 28 at risk in the other two groups, respectively. No deaths are listed in any group. The safety denominators differ from some outcome-summary counts, so each set of figures should be interpreted using its own stated population.

These counts describe serious adverse events recorded in the registry. They do not establish that treatment caused an event or that an event was unrelated to treatment. The posted summary does not provide the event-level timing, clinical context, duration, or adjudication details needed to make those judgments. The registry also lists serious-event terms with percentages, including infusion related reaction, breast cancer, hyperventilation, pneumomediastinum, cerebral infarction, and all-cause mortality. Those terms and percentages should be read as registry-reported summaries rather than evidence of causation.

Other adverse events affected 25 participants in the AMG 157 plus cat immunotherapy group, 18 in the AMG 157 placebo plus cat immunotherapy group, 18 in the AMG 157 plus cat immunotherapy placebo group, and 19 in the placebo-placebo group. These are group-level counts, not a complete account of event type or severity. Differences in counts alone do not establish comparative safety, especially without event definitions, exposure details, and uncertainty estimates.

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

The posted primary result is an estimate of a specific model-based contrast in TNSS area under the curve during the first hour after cat Nasal Allergen Challenge at Week 104. It points toward a lower mean score in the group receiving AMG 157 with cat immunotherapy than in the group receiving cat immunotherapy with AMG 157 placebo. Because higher TNSS values indicate more severe symptoms, that direction corresponds to a lower symptom score in the intervention group for this assessment.

The confidence interval, from -1.51 to 0.49 for the net mean difference, includes zero, and the reported p-value is 0.314. The evidence therefore does not establish a statistically clear difference for this primary comparison. It also does not establish that the two regimens are equivalent or that there is no possible difference. The interval allows for estimates on both sides of zero, and its width reflects uncertainty about the magnitude and direction of the contrast.

The endpoint is not a direct measure of lasting tolerance in everyday life. It records a participant-rated nasal symptom response during a defined challenge assessment. Although the study objective concerns induction of tolerance to cat allergen, the primary result should be described by the measure and timepoint actually analyzed. It should not be recast as proof of a lasting clinical state or a conclusion about all symptoms and exposures.

The finding also does not answer every comparison among the four randomized groups. The reported primary contrast isolates the comparison between two groups receiving cat immunotherapy, with AMG 157 versus its placebo. The other group summaries and the listed secondary outcomes address additional treatment combinations or measures, but their findings cannot be inferred from the primary result.

Finally, the result is not a recommendation for an individual. It is a statistical summary from a randomized clinical trial and should be interpreted with the limits of the registry record, including missing detail about participant flow, missing measurements, and multiplicity. The posted result supports a cautious description of the estimated contrast, not a broad claim of benefit, lack of benefit, or equivalence.

14. Why This Trial Matters Statistically

This trial illustrates why a clinical question and its statistical estimand must be read together. The study objective refers to tolerance, while the reported primary endpoint is a participant-rated symptom-score area under the curve during a cat allergen challenge at Week 104. Statistical interpretation depends on keeping the broader objective distinct from the operational outcome used for the primary comparison.

The design includes four combinations of active treatment and placebo, but the primary contrast is specifically between two groups that both received cat immunotherapy. This makes the contrast relevant to the incremental comparison of AMG 157 against its placebo in the context of cat immunotherapy. It does not automatically describe the effect of cat immunotherapy, nor does it answer every possible comparison among the four groups. Clear identification of the comparator is essential when interpreting a multi-arm trial.

The result also demonstrates why a point estimate, confidence interval, and p-value should be considered together. The negative estimate gives a direction, while the interval crosses zero and the p-value is 0.314. Neither a single point estimate nor a threshold-based label captures the full uncertainty. The interval communicates that the available evidence is compatible with a range of possible differences.

Finally, the record shows the value of separating observed outcomes from planning calculations. A sample-size illustration based on an observed effect is not an estimate of achieved power and should not be mistaken for an additional result. Statistical reporting is strongest when the target population, endpoint, comparison, model, uncertainty, and limits of the registry record remain explicit.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The registry record gives the primary model and covariates but does not report all information needed to independently reproduce the analysis. It does not specify the covariance structure, detailed handling of incomplete repeated measures, or sensitivity analyses for missing data. It also does not provide a participant flow account explaining the relationship between enrollment, group counts, and the numbers contributing to each outcome.

The primary endpoint is based on participant-rated symptoms during a Nasal Allergen Challenge. Such a measure is directly relevant to the defined assessment, but its scope is narrower than a general statement about symptoms in daily life or lasting tolerance. The Week 104 result should not be generalized beyond the recorded measure, challenge setting, and comparison without supporting evidence.

The registry lists eight secondary outcomes but does not report a multiplicity strategy in the record. Without information about hypothesis hierarchy or adjustment, secondary findings would need cautious interpretation, particularly if many outcomes are considered together. The posted primary p-value is interpretable for its stated analysis, but it does not resolve the multiplicity questions for the broader outcome set.

The record identifies randomization and triple masking but does not describe the procedures in detail. It also does not report the sample-size justification, recruitment targets, interim analyses, stopping rules, or detailed protocol for deviations from assigned treatment. These details are not reported in the registry record and should not be inferred.

Safety summaries provide counts and selected serious-event terms, but the posted information does not establish causal attribution or give enough clinical detail to characterize individual events. The outcome summaries and safety summaries also use their own stated group counts. Comparing them without information on exposure and analysis populations could be misleading.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Anti-TSLP (AMG 157) Plus Antigen-Specific Immunotherapy for Induction of Tolerance in Individuals With Cat Allergy — NCT02237196.
• Registry record last updated 2020-05-06; status last verified 2020-04.
• Results first posted 2020-05-06.
• 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.

19. Record Summary

NCT02237196 is a completed randomized, triple-masked, parallel-group Phase 1 and Phase 2 trial of AMG 157 and cat immunotherapy in people with cat allergy or cat hypersensitivity. Enrollment was 121. The primary endpoint was TNSS area under the curve from 0 to 1 hour of the cat Nasal Allergen Challenge at Week 104.

The primary reported comparison was AMG 157 plus cat immunotherapy versus AMG 157 placebo plus cat immunotherapy. Its net mean difference was -0.51, with a 95% confidence interval from -1.51 to 0.49 and p = 0.314. The interval includes zero, leaving uncertainty about the size and direction of the difference. The registry also lists eight secondary outcomes and four treatment groups. Important details about missing data, multiplicity, participant flow, and several modeling procedures are not reported in the registry record.