Confirmatory Phase II Study of Blinatumomab (MT103) in Patients With Minimal Residual Disease of B-precursor Acute Lymphoblastic Leukemia (ALL): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Confirmatory Phase II Study of Blinatumomab (MT103) in Patients With Minimal Residual Disease of B-precursor Acute Lymphoblastic Leukemia (ALL) (NCT01207388), a na phase 2 study. The primary outcome is Percentage of Participants With a Minimal Residual Disease (MRD) Response Within the First Treatment Cycle.

2. Clinical Question

3. Trial Design

This was a confirmatory, multicenter, single-arm Phase II study of blinatumomab in adult patients with minimal residual disease of B-precursor acute lymphoblastic leukemia. The registry lists the study as completed, with enrollment of 116. Its start is recorded as 2010-11 and primary completion as 2014-02. These details describe the registry record; the record does not provide a randomized control group against which to compare outcomes.

Participants received blinatumomab by continuous intravenous infusion at a constant flow rate of 15 μg/m²/day for 28 days, followed by a 14-day infusion-free period, for up to 4 cycles. Masking is listed as none. Allocation is listed as NA, consistent with the single-group design. The registry does not report further details about treatment adherence, interruptions, dose changes, or the number of participants who received each cycle.

The primary endpoint was the percentage of participants with an MRD response within the first treatment cycle. The primary endpoint population required a baseline central-laboratory Ig-TCR PCR assay with the minimum required sensitivity of 1 x 10^-4. Secondary outcomes listed in the record include relapse-free survival, overall survival, mortality after allogeneic hematopoietic stem cell transplant, time to hematological relapse, duration of complete MRD response, MRD-level change in nonresponders, adverse events, and change in EORTC-QLQ-C30 scales.

Although enrollment is reported, the number assessed for the primary endpoint, the number who completed treatment, and the number contributing to each secondary outcome are not reported in the registry record. A detailed statistical analysis plan, including prespecified methods for the listed secondary outcomes, 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: Primary endpoint full analysis set (Prim EP FAS) included all participants with an Ig TCR PCR MRD assay with the minimum required sensitivity of 1 x 10\^-4 at central lab established at Baseline.

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: Full analysis set (all participants who received any infusion of blinatumomab)

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants With a Minimal Residual Disease (MRD) Response Within the First Treatment Cycle, measured over During the first cycle (6 weeks).

The primary endpoint is the percentage of participants with a minimal residual disease response within the first treatment cycle. It focuses on a laboratory measure of residual leukemia: at the end of the first cycle, bone marrow aspiration or biopsy was evaluated by the central MRD laboratory. The registry defines a complete MRD response as no PCR amplification of individual rearrangements of immunoglobulin or T-cell receptor genes after completion of the first cycle.

The endpoint population was not simply described as everyone enrolled. It included participants with a central-laboratory Ig-TCR PCR MRD assay at baseline that met the minimum required sensitivity of 1 x 10^-4. The number meeting this definition is not reported in the registry record. The registry gives the timeframe as during the first cycle (6 weeks) and describes assessment at the end of the first cycle (Day 29). Both descriptions are retained as registered; further reconciliation of the timing is not reported in the registry record.

In general, a response proportion gives the share of an analyzed group meeting a stated outcome definition. A confidence interval communicates uncertainty around that estimate. These are useful ways to describe a single-group endpoint, but they do not by themselves establish what would have happened under a different treatment. The registry record does not report the observed response percentage or its 95% confidence interval, so the magnitude and precision of the primary endpoint cannot be evaluated from the reported information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The main reported endpoint is a proportion: the percentage of participants meeting the complete MRD-response definition within the first treatment cycle. In general, a proportion is calculated from a count of participants meeting the outcome divided by the relevant analyzed group. The registry record does not report the response count, endpoint denominator, or resulting percentage, so the estimate cannot be reconstructed from the enrollment figure alone.

The primary endpoint population is defined by assay availability and sensitivity. It includes participants with a central-laboratory Ig-TCR PCR MRD assay at baseline with the minimum required sensitivity of 1 x 10^-4. This population definition is important because the analyzed group for an outcome may differ from the full enrolled group. The number of participants satisfying the definition is not reported in the registry record. The record also does not state how it handled missing or unevaluable endpoint assessments.

The registry specifies a 95% confidence interval as the measure of dispersion for the primary endpoint. In general, a confidence interval expresses uncertainty around an estimated response proportion. A narrower interval indicates greater precision under the method used, while a wider interval indicates less precision. The interval’s interpretation depends on the estimation method and the data used. The method for calculating the primary endpoint interval is not reported in the registry record, and neither the interval nor its estimate is reported.

Because the study is single-group, the primary analysis is not a randomized comparison between treatment arms. A single-group response estimate can describe the observed outcome in the defined population, but it does not provide a treatment-versus-control contrast. In general, random allocation helps make groups comparable with respect to measured and unmeasured factors; this study has no randomized comparison group. The registry lists allocation as NA and masking as none. Further details of the statistical analysis plan are not reported in the registry record.

The registry lists several secondary outcomes, including time-to-event outcomes such as relapse-free survival, overall survival, and time to hematological relapse. In general, time-to-event methods account for both the time until an event and participants who have not experienced the event by the end of observation. The specific definitions, censoring rules, estimators, and models for these outcomes are not reported in the registry record. No result or analytic detail should be inferred merely from an outcome’s presence in the registry.

Other listed outcomes include MRD-level change, duration of complete MRD response, adverse events, and change in EORTC-QLQ-C30 scales. In general, continuous measurements can be described using a measure of central tendency and a measure of variability, while event outcomes can be described with counts or proportions. The registry record does not report the statistical methods, summary estimates, or uncertainty measures for these secondary outcomes. It also does not report whether assumptions such as distributional form were assessed or how repeated measurements were handled.

The record lists no analysis entries. That does not identify the methods used in any sponsor analysis; detailed analysis methods are not reported in the registry record. In particular, the record does not report the inferential tests, model specifications, covariate adjustments, missing-data methods, or multiplicity procedures used for the outcomes.

The sample-size assumptions describe planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The target effect is described as a stated fraction of the observed effect. For time-to-event planning, the illustrations use the total number of events; for other outcomes, they use participants per arm. These are hypothetical planning assumptions, not the design of the registered single-group study, and they are not observed power. The registry does not report a trial-specific sample-size justification or the observed effect values used for those illustrations.

In general, over-dispersion arises when variation in the data exceeds what a simple statistical model assumes; accounting for it can affect uncertainty estimates. The registry record does not say that over-dispersion was assessed or relevant to the primary endpoint. No model or variance adjustment should be attributed to the study without a registry report of it.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Blinatumomab")
n      <- c(113)
events <- c(87)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Blinatumomab  113  87  77.0  68.1  84.4  68.4  83.8  68.4  83.8

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint alongside multiple secondary outcomes. When many outcomes are examined, the chance of at least one apparently notable finding can increase. In general, multiplicity procedures can control that risk or clarify which outcomes are confirmatory and which are exploratory. The registry record does not report a multiplicity adjustment, a testing hierarchy, or how the outcomes were prioritized beyond identifying the MRD-response measure as primary.

The record lists no analysis entries. It does not report whether interim analyses were planned or conducted, whether any outcome analyses were prespecified in a statistical analysis plan, or how secondary outcomes were handled statistically. Those details are not reported in the registry record and should not be inferred from the list of outcomes.

The primary endpoint population required a qualifying baseline central MRD assay. The record does not report how many enrolled participants met that criterion, how many had an endpoint assessment, or how missing and unevaluable assessments were treated. In general, missing endpoint data can affect both the estimate and its uncertainty, especially if missingness is related to outcome status. The registry record does not report a missing-data assumption, imputation procedure, sensitivity analysis, or other approach for evaluating that issue.

The listed secondary outcomes may have different populations, follow-up requirements, and missing-data considerations. Their analysis populations and methods are not reported in the registry record. Consequently, enrollment alone does not establish the denominator for any specific outcome, and the listed outcomes cannot be assumed to share one analysis population.

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: pyrexia (14.7%), tremor (6.9%), aphasia (5.2%), encephalopathy (5.2%), neutropenia (4.3%).

The registry safety entries list 73 participants affected among 116 at risk for serious adverse events, and 111 among 116 at risk for other adverse events. The record also lists 67 deaths. These figures should be read as registry-reported counts, not as evidence that an event was caused by blinatumomab. A single-group study has no concurrent control group for comparing event frequencies, and the record does not provide a causal attribution analysis.

The serious-event terms listed include Pyrexia (14.7%), Tremor (6.9%), Aphasia (5.2%), Encephalopathy (5.2%), Neutropenia (4.3%), and Overdose (4.3%). These are registry-listed percentages; the record does not provide the denominator or additional detail for each term in the posted safety listing. The terms do not represent an exhaustive account of all possible events, and the registry entry does not explain the criteria used to select these listed terms.

Interpretation also depends on the observation period, event definitions, ascertainment, and whether participants could contribute more than one event. These details are not reported in the registry record. The count of deaths is not accompanied by cause or timing information in the record, so it should not be treated as a treatment-related death count.

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

The registry record documents a Phase II, single-group study of blinatumomab in adults with B-precursor ALL and minimal residual disease. It specifies an MRD-response outcome, a central-laboratory assessment, and a complete-response definition based on PCR amplification of immunoglobulin- or T-cell receptor-gene rearrangements. It also lists secondary outcomes and safety counts.

However, the observed primary response percentage and its 95% confidence interval are not reported in the registry record. As a result, the primary finding’s size and precision cannot be described from this record. Enrollment is reported as 116, but the number included in the primary endpoint population is not reported in the registry record. Without that denominator and the outcome count, readers cannot assess the endpoint result from the listed enrollment.

Even if an outcome estimate were available, this single-group design would describe outcomes among participants receiving the study treatment, not the difference between treatment and a randomized control. The study cannot establish from its design alone what would have happened to comparable participants under another treatment or no treatment. That distinction limits causal interpretation; it does not negate the descriptive value of carefully defined outcomes.

The safety entries provide counts and selected event terms, but do not establish that treatment caused the events. The record does not provide a control group, detailed attribution, event timing, or cause of death. Those missing details constrain comparisons and causal conclusions.

In general, a registry record is one source for understanding a study’s design and reported outcomes. It may not contain every analysis or detail needed to assess the evidence fully. Here, the results and analytical details needed to evaluate the primary endpoint are not reported in the registry record, so conclusions about the observed MRD-response frequency or its precision cannot be drawn from the record alone.

14. Why This Trial Matters Statistically

This study illustrates why an endpoint definition and its analysis population matter as much as an outcome label. The primary outcome is not simply any reduction in MRD: the registry defines complete response through a central-laboratory PCR assessment and specifies a baseline assay-sensitivity requirement for inclusion in the primary endpoint population. Those details clarify what the endpoint is intended to represent and which participants are eligible to contribute.

The record also illustrates the distinction between a study’s enrollment and an outcome-specific denominator. Enrollment is reported as 116, while the size of the primary endpoint population is not reported in the registry record. Without the denominator and response count, neither the response percentage nor its precision can be evaluated. This is a practical reminder that a reported enrollment number cannot automatically be used to interpret every outcome.

Its single-group design further emphasizes the difference between describing an outcome and estimating a comparative treatment effect. A response proportion can be informative as a description of the study group, but a control group is needed for a direct comparison under the study design. No randomized comparison is part of this record.

Finally, the record lists several outcomes and safety counts without reporting their analysis methods or the primary endpoint result. That gap makes registry transparency and outcome-specific reporting consequential for statistical interpretation. The planning assumptions described in the record are also distinct from the actual study design: hypothetical two-arm sample-size illustrations do not constitute observed power or a randomized analysis of this single-group trial.

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 main limitation for interpreting the primary endpoint is that its observed response percentage and 95% confidence interval are not reported in the registry record. The record also does not report the endpoint response count or the number included in the primary endpoint full analysis set. Enrollment of 116 therefore does not supply the missing endpoint denominator.

The study is single-group, with no randomized comparator. Outcomes cannot be directly contrasted with outcomes under another treatment within this design, and treatment effects cannot be isolated from other influences through a randomized between-group comparison. Masking is listed as none; the record does not provide further information on procedures that might affect outcome assessment beyond central laboratory evaluation.

The record defines the primary endpoint population by baseline assay availability and sensitivity, but does not report how many participants met those criteria or how missing or unevaluable follow-up assessments were handled. It also does not report the statistical analysis plan, the method used for the confidence interval, or detailed methods for the secondary outcomes. The registry lists no analysis entries.

For safety, the record gives event counts and selected serious-event terms but does not report sufficient detail about timing, event-level definitions, attribution, or the cause of deaths. The absence of a control group also limits comparative safety interpretation. These limitations constrain what can be concluded from the registry record; they do not establish that the study lacked additional analyses outside the record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Confirmatory Phase II Study of Blinatumomab (MT103) in Patients With Minimal Residual Disease of B-precursor Acute Lymphoblastic Leukemia (ALL) — NCT01207388.
• Registry record last updated 2020-02-10; status last verified 2020-01.
• Results first posted 2015-02-12.
• 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

NCT01207388 is a completed Phase II, multicenter, single-group study of blinatumomab in adults with minimal residual disease of B-precursor acute lymphoblastic leukemia. The registry reports enrollment of 116, a start of 2010-11, and primary completion in 2014-02.

The primary endpoint was the percentage of participants with complete MRD response within the first treatment cycle, assessed by central-laboratory PCR. Participants received continuous intravenous blinatumomab at 15 μg/m²/day for 28 days, followed by a 14-day infusion-free period, for up to 4 cycles.

The primary response estimate and 95% confidence interval are not reported in the registry record. The record lists secondary outcomes and safety counts, but provides no randomized comparator. It lists no analysis entries, and detailed statistical methods, missing-data handling, and multiplicity procedures are not reported in the registry record.