Study of Fc-Optimized Anti-CD19 Antibody (MOR00208) to Treat B-cell Acute Lymphoblastic Leukemia(B-ALL): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Fc-Optimized Anti-CD19 Antibody (MOR00208) to Treat B-cell Acute Lymphoblastic Leukemia(B-ALL) (NCT01685021), a na phase 2 study. The primary outcome is Overall Response Rate (ORR).

2. Clinical Question

This is therefore a descriptive, single-arm clinical question: what responses and safety events were recorded among participants receiving MOR00208 in this study? It is not a randomized comparison of MOR00208 against another treatment or against no treatment. Without a concurrent control group, differences between treated participants and an external population would be vulnerable to differences in eligibility, disease status, follow-up, and other factors. The registry record does not provide enough detail to establish how any such external comparison should be made.

The study record also lists response duration, safety, pharmacokinetics, and immunogenicity among its secondary outcomes. Those outcomes add different kinds of information, but they do not change the primary question about the proportion of participants with CR or PR. Numerical results for the primary response endpoint are not reported in the registry record, so the clinical question cannot be answered from the posted primary outcome result.

3. Trial Design

The registry describes a phase IIa, open-label, multicentre, single-group study of MOR00208 in adults with relapsed or refractory B-ALL. The sponsor was MorphoSys AG. The study began in 2013-04, had a primary completion date of 2015-03, and is listed as terminated. Enrollment was 22 participants.

Participants received an intravenous infusion of MOR00208, described as a humanized Fc-engineered anti-CD19 antibody. Because the study was open-label, treatment was not masked. The record lists no allocation to different study groups and describes a single-group model. There was no randomized control arm, so the design can describe outcomes observed during treatment but cannot by itself separate treatment effects from the course of disease, other care, or other influences.

The primary outcome was ORR, defined as CR plus PR. The specified assessment period was throughout the study until progression, with assessment after each treatment cycle. Secondary outcomes included response duration assessed using hematology, bone marrow aspirates or biopsy, and CT; safety assessments including adverse events, laboratory data, vital signs, ECG, and physical examination; pharmacokinetics; and the number of participants developing anti-MOR00208 antibodies. Safety is listed more than once among the secondary outcomes in the registry record.

The registry record does not report the reason for termination, the number of participants who completed treatment or follow-up, treatment exposure, dose, eligibility criteria in detail, or the planned statistical analysis. These omissions limit assessment of how the study was conducted and how completely outcomes were observed. The record also does not explain whether termination affected follow-up or analysis. Such details should not be inferred from the status label alone.

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

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 Overall Response Rate (ORR), measured over Throughout during study until progression, after each treatment cycle.

Overall response rate is a binary endpoint: each participant is classified according to whether they had a complete remission or a partial remission, and the response rate expresses the share of the analyzed group who met either response definition. The registry defines ORR as CR plus PR and describes the endpoint as measuring antitumor activity of MOR00208. Assessments were specified after each treatment cycle and throughout the study until progression.

Combining complete and partial remission into one endpoint can provide a summary of participants who experienced either degree of response, rather than focusing only on complete remission. It is a commonly interpretable type of outcome because it classifies participants as having or not having a recorded response. That general property does not establish whether the endpoint is clinically meaningful in a particular setting; interpretation depends on the response definitions, assessment process, timing, and population.

The registry record does not report the observed number of participants with CR, the number with PR, or the resulting ORR. It also does not provide the detailed criteria used to classify response, the review procedures, or the handling of participants whose response status was unknown. Therefore, the endpoint definition is available, but the primary result and the precision of that result cannot be evaluated from the registry record.

Response duration is listed separately as a secondary outcome. It addresses how long a response lasts among participants who respond, rather than how many participants respond. The registry record does not report a numerical result for response duration either. These two outcomes answer related but distinct questions and should not be treated as interchangeable.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help clarify what can and cannot be learned from this record. The explanations below are general; they do not describe an unreported analysis plan for this study.

What does a single-group design estimate?

In a single-group study, the observed response proportion describes the participants who received the study intervention and were included in the analysis. It does not directly estimate a difference between MOR00208 and a comparator, because no comparator group was included. A comparison with historical experience would require suitable external data and careful attention to differences in participants, outcome definitions, and follow-up. The registry record does not report such a comparison.

The design can be useful for collecting preliminary information, including the frequency of observed responses and adverse events. But a response observed during treatment does not by itself show that treatment caused the response. Disease course, other care, participant selection, and assessment practices can also matter. In an open-label study, participants and investigators know that the study treatment is being given; that knowledge may influence some assessments or reporting. The registry record does not describe procedures intended to address that possibility.

What would uncertainty around ORR mean?

In general, a confidence interval describes uncertainty around an estimate. For a response proportion, an interval would communicate how compatible the observed data are with a range of underlying response proportions under the chosen statistical method. A narrow interval would indicate greater precision than a wide interval. The width depends in part on the number of participants with usable outcome information and on the observed response proportion.

No ORR estimate or confidence interval is reported in the registry record. Therefore, the precision of the primary endpoint cannot be assessed. Enrollment alone is not enough to determine precision, because the response results and analysis population are also needed. A confidence interval, if reported, would describe statistical uncertainty under its assumptions; it would not address bias from the study design or establish causality.

Why distinguish participants from events?

Adverse-event summaries can count participants who experienced at least one event, or they can count the total number of events. These quantities answer different questions. A participant count indicates how many people were affected at least once; an event count can include repeated events in the same person. The registry’s safety group reports numbers of participants at risk and affected for serious and other adverse events. It does not give total event counts or participant-level recurrence information in the registry record for this analysis.

Similarly, percentages attached to specific serious adverse event terms should be read as term-specific summaries, not as a mutually exclusive partition of participants. One participant may experience more than one type of event. The registry record does not explain the event-level counting rules for those terms, so the percentages should not be added together or interpreted as a single overall rate.

What does over-dispersion mean in general?

For count outcomes, a simple statistical model may assume that the variability of counts follows a particular relationship to their average. Over-dispersion means the observed variation is greater than that model expects. If it is ignored, uncertainty can be understated and tests can appear more decisive than warranted. This is a general issue for count data; the primary endpoint in this study is a participant response classification, and the registry record does not report a count-model analysis or an over-dispersion assessment.

How should planning illustrations be understood?

Planning calculations are not observed trial outcomes. The registry-associated sample-size assumptions describe illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They describe detecting a stated fraction of the observed effect. The assumptions specify participants per arm for ordinary outcomes and total events for time-to-event outcomes.

Those planning assumptions are distinct from the actual single-group study design, which had no two-arm allocation. They therefore should not be read as the trial’s original design rationale or as evidence that the study had a particular probability of detecting an effect. The registry record does not report the trial’s own sample-size justification. A planning illustration also does not establish that an effect is real, clinically important, or reproducible; it only describes a calculation under its stated assumptions.

The registry record lists no statistical analyses. It does not state which confidence-interval method, hypothesis test, analysis population, or missing-outcome procedure was planned or used. Without those details and without the primary result, a statistical reanalysis of the response endpoint is not possible from the information recorded.

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("MOR00208 (Formerly Xmab5574)")
n      <- c(22)
events <- c(2)
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  MOR00208 (Formerly Xmab5574)  22  2  9.1  1.1  29.2  2.5  27.8  2.8  28.0

11. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when several outcomes, time points, subgroups, or statistical tests are examined. In general, testing many hypotheses can increase the chance of at least one apparently notable result arising by chance. A prespecified hierarchy or adjustment can address some multiplicity concerns, but the choice depends on the study question and analysis plan. The registry lists one primary outcome and several secondary outcomes, including response duration, safety, pharmacokinetics, and immunogenicity. It does not report a multiplicity strategy or explain how the secondary outcomes were prioritized.

The registry record does not report a statistical analysis plan, analysis populations, or the handling of missing outcome data. It is therefore not possible to determine whether all enrolled participants were included in the primary analysis, how participants without an assessable response were classified, or how incomplete follow-up affected response duration and safety summaries. These issues matter because excluding participants or treating unknown responses differently can change an estimated response proportion.

General approaches to missing data rely on assumptions about why information is missing and how the missing outcomes relate to observed information. Those assumptions cannot be evaluated without information on missingness and the planned analysis. No such details are reported in the registry record. The number enrolled should not be treated as a confirmed denominator for every endpoint unless the analysis population and outcome completeness are stated.

The record also does not report interim analyses, stopping boundaries, or any adjustment associated with repeated monitoring. Their presence or absence in the conduct of the study cannot be inferred. The terminated status does not, on its own, reveal why the study ended or whether termination was related to efficacy, safety, recruitment, or another reason.

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: disease progression (27.3%), pyrexia (22.7%), febrile neutropenia (18.2%), sepsis (13.6%), tumor lysis syndrome (9.1%).

The registry safety summary lists 22 participants at risk for serious adverse events, with 17 affected. For other adverse events, it lists 22 at risk and 22 affected. These figures describe participants recorded as experiencing events, not the total number of events. A participant may experience more than one event, and the record does not give the number of repeated events or their duration.

The serious adverse event terms listed include Disease Progression (27.3%), Pyrexia (22.7%), Febrile Neutropenia (18.2%), Sepsis (13.6%), Tumor lysis syndrome (9.1%), and Diarrhoea (9.1%). The registry record does not provide counts for these individual terms in the information, nor does it specify the counting convention for the term percentages. They should not be summed or interpreted as mutually exclusive categories.

The record lists 5 deaths in the MOR00208 group. It does not report a causal attribution linking the deaths or the listed events to treatment. Nor does it provide timing, exposure-adjusted rates, severity details beyond the serious-event designation, or a comparison group. These summaries therefore describe reported safety events in the study group; they do not establish whether MOR00208 caused an event or how its safety compares with another treatment.

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

The registry record establishes that MOR00208 was studied in a phase IIa, open-label, single-group trial enrolling 22 adults with relapsed or refractory B-ALL. It defines the primary outcome as ORR, comprising complete remission and partial remission, assessed after each treatment cycle and during the study until progression. It also posts participant-level safety summaries and a list of serious adverse event terms.

However, the primary response result is not reported in the registry record. There is no response count, ORR estimate, or confidence interval in the information available for this analysis. Thus, the primary endpoint cannot be used to quantify observed antitumor activity or its statistical precision. The enrollment count does not substitute for an efficacy result.

The safety data indicate that serious and other adverse events were recorded among participants, and the record lists 5 deaths. These observations warrant careful descriptive reading, but they do not identify causation. The registry record does not include a control group, detailed event narratives, exposure-adjusted summaries, or a reported causal assessment. It is not possible to distinguish events attributable to treatment from events related to disease or other circumstances using these group summaries alone.

The single-group, open-label design is suited to describing experience within the treated group, but it cannot provide a randomized estimate of comparative effect. Interpretation is further limited by the absence of a reported analysis plan, analysis populations, missing-data methods, and numerical primary endpoint results. The status of terminated is recorded, but the reason for termination is not reported in the registry record.

Accordingly, the record supports a description of the trial’s design, enrollment, endpoint definition, and posted safety summaries. It does not support a precise estimate of response, a comparison with another treatment, or a causal conclusion about efficacy or adverse events. Those limits should remain central when interpreting the information.

14. Why This Trial Matters Statistically

This trial illustrates a central statistical distinction: describing outcomes in a treated group is not the same as estimating a treatment effect. A single-group design can document what was observed among participants who received MOR00208, but without a concurrent comparator it cannot isolate the contribution of treatment from disease course, other care, selection, or assessment processes. That distinction is especially important when interpreting a response endpoint as evidence of antitumor activity.

The registry record also shows why an endpoint definition and an endpoint result are different forms of information. ORR is clearly defined as CR plus PR, and the assessment schedule is described. Yet the response count and rate are not reported in the registry record. Readers can understand the intended measure, but cannot estimate its magnitude or precision. A defined outcome without its numerical result cannot answer the primary statistical question.

Safety summaries provide another useful lesson. Counts of participants affected are not event counts, while percentages attached to individual terms are not necessarily mutually exclusive. Without event-level details, timing, or exposure information, a list of serious adverse events cannot be converted into a comparative safety estimate or a causal conclusion.

Finally, the record identifies substantial gaps relevant to reproducibility and interpretation: the statistical analysis plan, missing-data approach, analysis population, reason for termination, and numerical primary outcome are not reported. Recognizing these gaps is part of statistical interpretation, not a judgment about what happened. The trial remains informative as a record of a phase IIa single-group investigation, while the limits of the posted information restrict the conclusions that can be drawn.

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.

Several limitations specific to this study affect interpretation. The design was single-group and open-label, with no randomized comparator. Consequently, the registry record cannot support a direct estimate of how outcomes under MOR00208 differed from outcomes under another treatment. Knowledge of treatment may also influence outcome assessment or event reporting, although the record does not describe the extent of that risk or any steps taken to limit it.

The primary endpoint result is not reported in the registry record. The absence of a response count, rate, and precision estimate prevents quantitative assessment of the stated primary question. The record also does not provide the detailed response criteria or independent review procedures, making it difficult to assess how response classifications were determined.

Although 22 participants were enrolled, the record does not report the analysis population, treatment exposure, follow-up completeness, or numbers assessed for each outcome. It does not describe missing-data handling or explain whether participants with unassessable responses were included in the primary analysis. The reason for the terminated status is also not reported in the registry record, so its implications for follow-up and analysis are unknown.

Safety interpretation is limited by the lack of event-level counts, timing, recurrence, exposure-adjusted summaries, and causal attribution. A concurrent comparison is also absent. The record lists secondary outcomes but does not report their numerical results in the information available for this analysis. It does not report a statistical analysis plan, multiplicity procedure, interim-analysis approach, or the study’s sample-size justification. These limitations restrict both statistical reproducibility and the strength of conclusions that can be drawn from the posted summaries.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study of Fc-Optimized Anti-CD19 Antibody (MOR00208) to Treat B-cell Acute Lymphoblastic Leukemia(B-ALL) — NCT01685021.
• Registry record last updated 2018-02-22; status last verified 2018-02.
• Results first posted 2018-02-22.
• 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.

19. Record Summary

The registry record describes NCT01685021 as a phase IIa, multicentre, open-label, single-group study of intravenous MOR00208, formerly Xmab5574, in adults with relapsed or refractory B-ALL. MorphoSys AG is listed as sponsor. The study began in 2013-04, reached primary completion in 2015-03, enrolled 22 participants, and is listed as terminated.

The primary endpoint was overall response rate, defined as complete remission plus partial remission, assessed after each treatment cycle and until progression. Its numerical result is not reported in the registry record. Safety summaries list 17 of 22 participants affected by serious adverse events and 22 of 22 affected by other adverse events; the record lists 5 deaths. The listed serious event terms include Disease Progression, Pyrexia, Febrile Neutropenia, Sepsis, Tumor lysis syndrome, and Diarrhoea. The single-group design and missing efficacy result limit comparative and causal interpretation.