Study to Assess the Efficacy and Safety of MEDI3506 in Adults With Uncontrolled Moderate-to-severe Asthma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study to Assess the Efficacy and Safety of MEDI3506 in Adults With Uncontrolled Moderate-to-severe Asthma (NCT04570657), a randomized phase 2 study. The primary outcome is Change From Baseline to Week 16 in Pre-bronchodilator (Pre-BD) Forced Expiratory Volume in the First Second (FEV1) as Measured in the Study Clinic.

2. Clinical Question

The primary outcome is a continuous lung-function measure in litres. The registry’s reported analyses compare each dose group with placebo using a model-based difference in least-squares means. The result therefore addresses average change in this specific measurement over the stated period; it does not by itself describe every aspect of asthma control, symptoms, safety, or longer-term outcomes.

The registry record gives results for two dose-group comparisons. It also lists secondary outcomes covering post-bronchodilator FEV1, asthma-control scores, respiratory quality-of-life scores, drug concentrations, and anti-drug antibodies. The record’s outcome group labels say Tozorakimab, while its title and intervention descriptions say MEDI3506. The relationship between these names is not explained in the registry record.

3. Trial Design

This is a Phase II, randomized, double-blind, placebo-controlled, parallel-group study of MEDI3506 in adults with uncontrolled moderate-to-severe asthma. The record describes the study as a proof-of-concept evaluation of efficacy, safety, pharmacokinetics, and immunogenicity in participants receiving standard of care. AstraZeneca is listed as the sponsor, and the study status is completed.

The brief description says approximately 228 participants would be randomized to three groups in a 1:1:1 ratio: MEDI3506 Dose 1, MEDI3506 Dose 2, or placebo. The registry enrollment field records 250. In the primary outcome results, the analysis group counts are 76 for Tozorakimab Dose A, 77 for Tozorakimab Dose B, and 81 for placebo. These are reported group-level counts for that outcome; the registry does not explain the difference between the planned approximate enrollment and the enrollment field in the results summary.

The primary outcome compares baseline with Week 16. Baseline is defined as the last measurement before the first injection of investigational product. Spirometry was performed in the study clinic before bronchodilator administration. The registry reports an MMRM analysis with least-squares means and differences, 80% confidence intervals, and one-sided p-values. Details of the model are described with the methods discussion.

The study dates are recorded as starting on 2020-09-17 and reaching primary completion on 2022-12-12. Further details about sequence generation, allocation concealment, dose amounts, treatment duration, and the trial’s original sample-size justification 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: Adult participants with uncontrolled moderate to severe asthma were randomised in a 1:1:1 ratio to receive tozorakimab (MEDI3506) Dose A (lower dose), tozorakimab Dose B (higher dose), or placebo. Of the 478 participants screened, 250 were enrolled, and of these, 15 were excluded from analysis due to invalidity of data (see limitations and caveats for further details).

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The ITT population included participants who were randomised and received any study intervention. Participants with data available are included.

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 Change From Baseline to Week 16 in Pre-bronchodilator (Pre-BD) Forced Expiratory Volume in the First Second (FEV1) as Measured in the Study Clinic, measured over Baseline and week 16.

The primary endpoint is change from baseline to Week 16 in pre-bronchodilator forced expiratory volume in the first second, or FEV1, measured in the study clinic. FEV1 is the volume of air exhaled during the first second of a forced breathing manoeuvre. The registry records the measure in litres and specifies that spirometry took place before bronchodilator administration. Baseline is the last measurement before the first injection of investigational product.

As a continuous endpoint, FEV1 retains information about the amount of change rather than reducing participants to categories such as improved or not improved. The reported group summaries are least-squares means, which are model-based averages adjusted for the terms included in the analysis. The comparison of interest is the difference between each dose group’s adjusted mean change and the placebo group’s adjusted mean change.

In general, lung-function measurements can complement symptom and quality-of-life measures because they describe a different aspect of a respiratory condition. That general rationale does not make FEV1 a complete measure of asthma status. A Week 16 comparison cannot alone establish how participants felt, how their condition varied over time, or what happened after the stated assessment period. The registry record does not report a threshold for a clinically important FEV1 difference, so the size of the observed estimate should be read as a measured difference rather than assigned a clinical-importance label.

7. Results Posted in the Registry

• Tozorakimab Dose A: mean 0.15 versus 0.11 on control; difference 0.04 (95% CI -0.09 to 0.16), standardized effect d = 0.09; z-test p = 0.584.
• Tozorakimab Dose B: mean 0.12 versus 0.11 on control; difference 0.00 (95% CI -0.13 to 0.13), standardized effect d = 0.01; z-test p = 0.952.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Change From Baseline to Week 16 in the Asthma Control Questionnaire-6 (ACQ-6) Score

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • Tozorakimab Dose A: mean -0.93 versus -0.90 on control; difference -0.03 (95% CI -0.35 to 0.29), standardized effect d = -0.03; z-test p = 0.853.
  • Tozorakimab Dose B: mean -0.94 versus -0.90 on control; difference -0.05 (95% CI -0.36 to 0.27), standardized effect d = -0.05; z-test p = 0.772.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Tozorakimab Dose A and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Tozorakimab Dose B and the control. The interval gives the range of effects that remain compatible with the data.

Number of Participants With a Decrease in ACQ-6 Score ≥ 0.5 From Baseline to Week 16

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Tozorakimab Dose A: 72.6% (53/73) versus 68.8% (53/77) on control; risk difference 3.8 percentage points (95% CI -10.8 to 18.3), risk ratio 1.05 (0.86–1.30); unadjusted two-proportion z-test p = 0.612.
  • Tozorakimab Dose B: 75.7% (56/74) versus 68.8% (53/77) on control; risk difference 6.8 percentage points (95% CI -7.4 to 21.1), risk ratio 1.10 (0.90–1.34); unadjusted two-proportion z-test p = 0.348.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Tozorakimab Dose A and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Tozorakimab Dose B and the control. The interval gives the range of effects that remain compatible with the data.

Number of Participants Achieving ACQ-6 Well Controlled Status at Week 16

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Tozorakimab Dose A: 23.3% (17/73) versus 27.3% (21/77) on control; risk difference -4.0 percentage points (95% CI -17.9 to 9.9), risk ratio 0.85 (0.49–1.49); unadjusted two-proportion z-test p = 0.575.
  • Tozorakimab Dose B: 24.3% (18/74) versus 27.3% (21/77) on control; risk difference -2.9 percentage points (95% CI -16.9 to 11.0), risk ratio 0.89 (0.52–1.53); unadjusted two-proportion z-test p = 0.679.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Tozorakimab Dose A and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Tozorakimab Dose B and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes broaden the assessment beyond pre-bronchodilator FEV1. The registry lists post-bronchodilator FEV1, ACQ-6 asthma-control measures, St George’s Respiratory Questionnaire scores, serum concentrations, and anti-drug antibodies. The posted ACQ-6 comparisons include both average score change and binary definitions based on score change or control status.

Across the ACQ-6 results, the continuous estimates are close to zero relative to their uncertainty, and the sponsor-reported intervals include no difference. The binary analyses also have sponsor-reported odds-ratio intervals that include the no-association value. Taken together, these displayed asthma-control outcomes do not supply a clear contrasting pattern to the primary result. They are complementary measures, not direct substitutes for the lung-function endpoint.

The record lists 11 posted secondary outcomes, but the detailed results included in the record summary are not equally available for every listed outcome. In particular, a listed outcome should not be treated as evidence of a finding unless its results are reported. Results for additional endpoints and analyses not described in the available record summary are not reported in the registry record.

Unadjusted secondary results carry less weight because multiple outcomes and comparisons increase the chance of an apparently notable result arising by chance. The registry record does not report a multiplicity adjustment or a hierarchy governing secondary tests. Their estimates can describe the observed data and help identify patterns, but they do not independently establish a confirmatory treatment effect. The primary endpoint and its prespecified analysis remain the central basis for assessing the study’s main statistical question.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Change From Baseline to Weeks 8 and 16 in Post-bronchodilator (Post-BD) FEV1 as Measured in the Study Clinic
• Serum Concentrations of Tozorakimab
• Number of Participants With Anti-drug Antibodies (ADAs)
• Change From Baseline to Week 16 in the Asthma Control Questionnaire-6 (ACQ-6) Score
• Number of Participants With a Decrease in ACQ-6 Score ≥ 0.5 From Baseline to Week 16
• Number of Participants Achieving ACQ-6 Well Controlled Status at Week 16
• Change From Baseline to Week 16 in St George's Respiratory Questionnaire (SGRQ) Domain and Total Scores
• Number of Participants With a Decrease in SGRQ Total Score of ≥ 4 Points From Baseline to Week 16

9. Statistical Interpretation

10. Statistical Methods Explained

The primary analysis is described as a mixed model for repeated measures, abbreviated MMRM. In general, this type of model analyzes measurements taken at multiple visits while accounting for the fact that repeated observations from the same participant are related. It can estimate group averages at a visit while using the repeated-measure structure specified in the model. The registry says visits within a participant were considered repeated measurements.

What was included in the primary model?

The registry lists fixed effects for baseline, background medication, geographic region, baseline inhaled corticosteroids total daily dose, visit, treatment, and the baseline-by-visit and treatment-by-visit interactions. These terms describe the adjustment structure reported for the analysis. The treatment-by-visit interaction allows the treatment-group contrast to vary across visits; the visit term accounts for the scheduled measurement occasions. The record does not provide further details about coding choices, covariance structure, estimation procedures, or model diagnostics.

The reported primary statistics are least-squares means and least-squares mean differences. In general, a least-squares mean is a model-based group mean, adjusted for the model terms, rather than simply the arithmetic average of the available observations. A least-squares mean difference compares those adjusted means. The sponsor reports 80% confidence intervals and one-sided p-values for the primary comparisons. The registry’s text describes the p-values as one-sided; it does not report the original significance threshold or a detailed testing plan.

How does the re-calculation differ?

The simple re-calculation uses the posted group summaries to estimate unadjusted mean differences. It does not reproduce the sponsor’s MMRM, its covariate adjustment, or its handling of repeated measurements. The displayed pooled standard deviations are approximate, derived from the posted standard errors, and the re-calculated results are therefore a separate summary-statistic analysis. General statistical principle: adjustment and repeated-measures modeling can yield uncertainty estimates and test results that differ from an unadjusted comparison, even when the point estimates are similar.

Because the registry reports the sponsor’s fitted model and the re-calculation is an approximation from summaries, the sponsor’s analysis is the appropriate reference for the study’s stated primary analysis. The re-calculation is useful as a check on the broad scale and direction of the comparison, but it should not be presented as a replacement for the reported model.

What do the secondary analyses add?

The record includes continuous outcomes, such as ACQ-6 score change, and binary outcomes, such as whether participants reached a stated score-change or control-status threshold. In general, continuous analyses compare averages, while binary analyses compare the occurrence of a defined category. The registry reports MMRM for the continuous ACQ-6 outcome and chi-squared analyses with odds ratios for the binary ACQ-6 outcomes. These methods answer different statistical questions, and an odds ratio is not the same quantity as a difference in average score.

General statistical principle: multiple outcomes and comparisons create multiple opportunities for an apparently notable result. A prespecified multiplicity strategy can control the interpretation of that collection of tests. The registry record does not report such a strategy, so the individual secondary p-values should not be read as though they were necessarily adjusted for the number of analyses.

The analysis population for the primary endpoint is described as the ITT population, defined in the record as randomized participants who received any study intervention; participants with data available are included. The record does not explain in detail how missing measurements were handled, whether any imputation was used, or what sensitivity analyses were performed. MMRM is the named primary method, but the label alone does not reveal all assumptions about missing observations.

General statistical principle: when outcomes are missing, the interpretation of a model depends in part on the assumptions and procedures used for those missing values. Those assumptions cannot be evaluated from the model name alone. The registry gives enough information to identify the broad model and its listed fixed effects, but not enough to reconstruct the full analysis.

11. Confidence Intervals and Precision

A confidence interval gives a range of values reasonably compatible with an estimate under the analysis used. In general, a wider interval indicates less precision, while a narrower interval indicates more precision. The interval is not a guarantee that the true value lies within its endpoints, and it does not show the probability that a particular value is correct.

For the primary comparisons, the sponsor reports 80% confidence intervals. For Tozorakimab Dose A versus placebo, the estimated difference is 0.036 litres, with an interval from -0.038 to 0.111. For Tozorakimab Dose B versus placebo, the estimate is 0.004 litres, with an interval from -0.071 to 0.079. Each interval crosses zero, the value corresponding to no difference between the adjusted group means. Thus the estimates have uncertainty that includes both directions of difference.

The intervals should be interpreted alongside the point estimates, endpoint scale, and analysis method. A confidence interval does not establish clinical importance; the registry record does not give a clinically important difference threshold for this endpoint. Nor does inclusion of zero prove equivalence. An equivalence conclusion would require a defined margin and a design and analysis aimed at evaluating that margin, which are not reported in the registry record.

The re-calculated comparisons use a different, unadjusted approach based on posted summaries. Their uncertainty ranges are not the sponsor’s MMRM intervals and should not be conflated with the reported 80% intervals. General statistical principle: interval width reflects both the variability in the data and the amount of information available, as well as the analysis method and confidence level. The reported intervals therefore provide context for the precision of the sponsor’s estimates, not a stand-alone judgment about the importance of an effect.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size illustrations are planning calculations based on the observed effect, not the trial’s original design assumptions. For the continuous comparisons shown, the figures are participants per arm. The stated calculation assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect set to the stated fraction of the observed effect. The trial’s own original sample-size justification and assumptions are not reported in the registry record.

The 80% power column gives the estimated participants per arm for a future two-arm comparison to have 80% power under those assumptions and for the specified effect size. The 90% power column gives the corresponding participants per arm for 90% power. In general, power is the chance of detecting an effect of the specified size if that effect is the true one and the calculation assumptions hold. These figures are not observed power for this completed study.

The rows that plan for 100%, 75%, or 50% of the observed effect illustrate how the assumed target changes the planning estimate. A smaller effect is harder to distinguish from random variation, so the planning calculation requires more participants. For example, the primary comparison planning figures increase when the assumed effect is reduced from the full observed effect to a smaller fraction. The figures are illustrations, not recommendations: they depend on the observed estimate and stated assumptions, and can be unstable when that estimate is small.

The planning figures should not be confused with actual group counts in the trial. They also do not establish that the original study was designed to detect the exact observed effect. The meaning of the planning output is conditional on the assumptions listed in the registry analysis summary.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 0.036; pooled standard deviation σ = 0.412.
2. n = 2 × (1.96 + 0.842)² × 0.412² / 0.036² = 2,055.4, rounded up to 2,056 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 0.036                      # observed difference in means
sigma <- 0.411942526526809                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(4570657)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 2,056 (80% power), 2,752 (90% power)
 75% of observed effect: n per arm = 3,655 (80% power), 4,892 (90% power)
 50% of observed effect: n per arm = 8,222 (80% power), 11,007 (90% power)
power.t.test: 2056.4 
Simulated power at n = 2,056 per arm: 0.800 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The sponsor’s primary analysis is reported as an MMRM comparison of least-squares mean changes. The reported difference is 0.036 litres for Tozorakimab Dose A versus placebo, with an 80% confidence interval from -0.038 to 0.111 and a p-value of 0.267. For Tozorakimab Dose B versus placebo, the reported difference is 0.004 litres, with an 80% confidence interval from -0.071 to 0.079 and a p-value of 0.473.

The simple re-calculations from posted summary statistics give the same rounded point estimates, but their unadjusted p-values are 0.584 and 0.952. The calculations are not reproductions of the sponsor’s fitted model: they use group-level summaries rather than the stated adjustment and repeated-measures structure. Differences in inferential results are therefore expected to be possible and do not, by themselves, demonstrate a registry discrepancy. The record marks the discrepancy flag as false.

For interpretation of the stated primary analysis, the sponsor’s model-based results take precedence over the simple re-calculation. Both presentations place the point estimates close to zero relative to the uncertainty shown, and the sponsor’s intervals include zero. The re-calculation is best used as a transparent, approximate comparison of posted summaries, not as an alternative primary analysis.

15. Multiplicity, Missing Data and Analysis Populations

The trial reports a primary endpoint, several secondary outcomes, and more than one comparison with placebo. When many outcomes or tests are examined, the chance of at least one result appearing unusual by chance can increase. General statistical principle: multiplicity procedures, such as a prespecified testing hierarchy or adjusted significance thresholds, can address that issue, but they affect how individual p-values should be interpreted.

The registry record does not report whether multiplicity was controlled, which outcomes were included in any testing hierarchy, or whether secondary analyses were intended as confirmatory or exploratory. It also does not report a complete statistical analysis plan or the original significance threshold for the primary test. The primary description notes one-sided p-values, while the sample-size illustration states a two-sided significance level of 0.05 for its planning calculation. These refer to different reported contexts and should not be assumed to describe a single, complete trial-testing strategy.

The primary population is described as participants who were randomized and received any study intervention, with participants who had data available included. That definition identifies the broad analysis population, but it does not explain how participants without a Week 16 measurement were treated. Detailed missing-data procedures, assumptions, imputation methods, and sensitivity analyses are not reported in the registry record. The use of MMRM does not, on its own, establish the assumptions made about missing outcomes.

These omissions limit how fully the analysis can be reproduced or how robustly its assumptions can be assessed. They do not change the reported estimates, but they matter when evaluating the strength of evidence across endpoints and the sensitivity of conclusions to incomplete data or multiple testing.

16. 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: asthma (2.6%), bronchitis (1.3%), acid peptic disease (1.3%), asthenia (1.3%), clavicle fracture (1.3%).

The registry reports serious adverse events for each outcome group. Serious adverse events were recorded for 1 participant in Tozorakimab Dose A, 4 participants in Tozorakimab Dose B, and 2 participants in placebo. The respective groups at risk are listed as 77, 77, and 81. The record reports zero deaths in each group.

These are descriptive counts. They do not establish that a difference between groups is due to treatment, and the registry summary does not provide a statistical comparison of serious adverse events. The record also lists serious adverse-event terms, including Asthma at 2.6%, Bronchitis at 1.3%, Acid peptic disease at 1.3%, Asthenia at 1.3%, Clavicle fracture at 1.3%, and Clostridium difficile colitis at 1.2%. Those terms and percentages should be read as the registry’s reported safety listing, not as a complete account of every possible safety outcome.

The summary reports other adverse events separately from serious adverse events, with counts of 25, 20, and 20 participants across the dose and placebo groups. The record does not provide enough detail in this summary to characterize event duration, severity distributions, or causal attribution. Safety counts should therefore be interpreted as a descriptive snapshot of the reported study data.

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

The primary result estimates the difference in average Week 16 change in pre-bronchodilator FEV1 between each dose group and placebo under the sponsor’s MMRM. The point estimates are close to zero, and the reported 80% confidence intervals include zero. The posted results therefore do not show a clear separation between either dose group and placebo on this endpoint, while retaining uncertainty about the size and direction of the underlying difference.

This does not prove that the groups are equivalent or that no effect exists. Equivalence requires a prespecified margin and an analysis designed to assess whether differences fall within that margin; neither is reported in the registry record. A result that does not clearly distinguish groups is also not a measure of whether a treatment might matter for every participant. It is an estimate of an average contrast in a defined outcome and study population.

The result does not resolve questions beyond the endpoint and follow-up described. The primary measure is clinic spirometry at Week 16, not a complete account of asthma symptoms, exacerbations, quality of life, or longer-term outcomes. Some of those areas appear among the secondary outcomes, but the registry’s multiplicity and missing-data details are limited. Nor do the safety counts alone establish comparative safety.

The registry record is a source of reported study results, not a substitute for a full protocol, statistical analysis plan, or complete clinical report. Dose labels differ between the study description and outcome group names, and the record does not explain that naming. These limits should be kept in view when interpreting the numerical estimates and when comparing them with evidence from other settings.

18. Why This Trial Matters Statistically

This trial provides an example of why an estimated effect and its precision should be read together. The primary point estimates are small in the endpoint’s litre scale, but point estimates alone do not show how much uncertainty remains. The sponsor’s intervals extend to both sides of zero, making the uncertainty central to interpreting what the results can support.

It also illustrates the distinction between a model-based trial analysis and a simple summary-statistic re-calculation. The sponsor’s MMRM uses baseline and other listed factors, as well as repeated measurements over visits. A re-calculation from group summaries is easier to inspect, but it does not reproduce that model. Similar point estimates do not make different analyses interchangeable, and differing p-values should be understood in light of the methods used.

The study’s secondary outcomes also demonstrate why a coherent pattern matters more than an isolated result. Lung function, asthma-control scores, and quality-of-life measures address related but distinct questions. With several outcomes and comparisons, an unadjusted secondary finding warrants more caution unless the analysis plan explains how multiplicity was handled.

Finally, planning illustrations based on observed effects are not a substitute for a trial’s original design rationale. They show how assumptions about the effect to detect influence participant requirements, but they do not establish what the completed trial was designed to detect. Reading estimates, intervals, analysis methods, and design information together is essential to a balanced statistical interpretation.

19. 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.

Several features of the registry record constrain interpretation. The study description uses MEDI3506 and Dose 1/Dose 2, while outcome group labels use Tozorakimab Dose A and Tozorakimab Dose B. The record does not explain the naming relationship, so the labels should be reported as recorded rather than treated as fully clarified.

The summary gives an enrollment field of 250 and separately describes approximately 228 planned randomized participants. It also reports outcome-specific group counts. The record does not explain the relationship among these figures. The primary analysis population is defined as randomized participants who received any study intervention, with available data included, but the handling of missing Week 16 measurements is not described in detail.

The sponsor’s primary results are reported with 80% confidence intervals and one-sided p-values. The complete original analysis plan, significance threshold, multiplicity strategy, model covariance structure, diagnostic checks, and sensitivity analyses are not reported in the registry record. These omissions limit independent reconstruction of the sponsor’s analysis and assessment of its assumptions.

The record also does not report a clinically important difference threshold for FEV1, detailed dose amounts, or the original sample-size justification. The planning illustrations are based on the observed effect and stated calculation assumptions, so they cannot fill that gap. Finally, the safety summary is descriptive and does not provide a full account of event timing, severity, attribution, or comparative statistical testing. These limitations affect how much can be concluded from the registry summary, without changing the values it reports.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Study to Assess the Efficacy and Safety of MEDI3506 in Adults With Uncontrolled Moderate-to-severe Asthma — NCT04570657.
• Registry record last updated 2024-01-30; status last verified 2024-01.
• Results first posted 2024-01-30.
• 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.

23. Record Summary

The completed Phase II study evaluated MEDI3506 in adults with uncontrolled moderate-to-severe asthma receiving standard of care. It is described as randomized, double-blind, placebo-controlled, and parallel-group, with two dose groups and placebo.

The primary endpoint was change from baseline to Week 16 in pre-bronchodilator FEV1. The sponsor’s MMRM comparisons reported least-squares mean differences of 0.036 litres and 0.004 litres versus placebo, with 80% confidence intervals that included zero. The registry also includes secondary asthma-control outcomes and descriptive safety counts.

The reported estimates should be interpreted with their uncertainty and the limits of the registry’s analysis details. Multiplicity procedures and detailed missing-data methods are not reported in the registry record. Outcome group names use Tozorakimab, while the study description uses MEDI3506; that terminology is not reconciled in the record.