A Study of Patients Who Received Inotuzumab Ozogamicin for B-cell ALL (Acute Lymphoblastic Leukemia) That Occurred Again After the Last Treatment: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Patients Who Received Inotuzumab Ozogamicin for B-cell ALL (Acute Lymphoblastic Leukemia) That Occurred Again After the Last Treatment (NCT05597085), a registered phase not stated study. The primary outcome is Number of Participants Who Achieved Complete Remission (CR) or Complete Remission With Incomplete Hematological Recovery (CRi) Following Treatment With InO.

2. Clinical Question

The study concerns adults with relapsed or refractory B-cell ALL treated with InO. The clinical question is descriptive: among the eligible participants whose records were retrieved and observed, how many had a recorded CR or CRi following treatment? The registry also lists secondary questions about minimal residual disease negativity among participants with CR or CRi, treatment cycles, and duration of remission.

The record describes a hospital-based electronic medical record review in India. It says the study sought data from 7 -10 hospitals and describes patients who received InO alone. Because no comparator is described, the record does not establish how outcomes under InO compare with outcomes under another treatment or with outcomes in an untreated group. The posted information does not report the primary remission count, so the clinical question cannot be answered from the primary outcome result in the registry record.

3. Trial Design

This is a completed, retrospective analysis of InO use in adult patients with relapsed or refractory B-cell ALL. The registry lists a start date of 2023-03-08, primary completion on 2023-07-10, and a completed status. The study description says that patient data, with personal details excluded, were collected from hospital-based electronic medical records in India. The primary outcome timeframe refers to InO treatment initiation from Apr 2018 through the end of follow-up in Apr 2023, with a maximum of up to 61 Months. It also says data were retrospectively collected from 08-Mar-2023 to 10-Jul-2023, approximately 4 months of this study.

The registry lists enrollment of 32 participants. The brief summary says around 55 patients were likely to be enrolled, so the stated expectation and the enrollment figure differ. The number whose data met the analysis-population criteria is not reported in the registry record. The analysis population is described as all eligible participants whose data were retrieved and observed.

One treatment group is described: adult patients whose B-cell ALL had returned after the last treatment or who had never responded to prior treatment, receiving InO. Allocation to treatment is not stated, and there is no described control group. The record therefore supports a descriptive account of this treated cohort, not a randomized estimate of a treatment contrast. Protocol details beyond the stated eligibility, treatment, outcome measures, and timeframe are not reported in the registry record. In particular, the record does not report the method used to select hospitals or patients, or further details on how records were abstracted.

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

Analysis population for the primary outcome, as defined in the registry: Analysis population included all eligible participants whose data were retrieved and observed in this 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.

Population: Eligible participants whose data was retrieved and observed in the study.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants Who Achieved Complete Remission (CR) or Complete Remission With Incomplete Hematological Recovery (CRi) Following Treatment With InO, measured over From InO treatment initiation (Apr 2018) till end of follow-up (Apr 2023) [Maximum up to 61 Months]; data retrospectively collected from 08-Mar-2023 to 10-Jul-2023 (approximately 4 months of this study).

The primary endpoint is the number of participants who achieved complete remission (CR) or complete remission with incomplete hematological recovery (CRi) following treatment with InO. It is a count outcome: it records how many participants met either remission definition, rather than measuring a continuous change in a laboratory value or time until an event. The registry describes the analysis population as eligible participants whose data were retrieved and observed.

The registry defines CR as 5% bone marrow blasts, no evidence of disease in the bone marrow, and recovery of peripheral blood counts. Its stated recovery thresholds are a platelet count of >100*10^9 cells/liter and an absolute neutrophil count of >1*10^9 cells/L. CRi is defined as 5% bone marrow blasts and no evidence of disease in the bone marrow, but with incomplete recovery of peripheral blood counts. These distinctions make the endpoint sensitive to whether remission is accompanied by the specified blood-count recovery.

As a general statistical point, a count of participants meeting a prespecified clinical definition can describe how often that outcome was observed in a cohort. Its interpretation depends on clear outcome definitions, consistent follow-up, and knowing how many participants were evaluated. The registry record names the endpoint and its timeframe, but does not report the number achieving CR or CRi. It therefore does not permit a numerical description of the primary remission result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General: what a retrospective analysis describes. In a retrospective analysis, researchers examine information recorded before the analysis rather than assigning participants prospectively to treatment groups for a randomized comparison. Here, the study description says data were collected from hospital-based electronic medical records in India, and the primary outcome timeframe covers treatment initiation from Apr 2018 through follow-up ending in Apr 2023. Such records can support descriptions of outcomes and events among the people represented in them. Their interpretation depends on which patients had usable records, how outcomes were recorded, and how follow-up was captured. Further information about those procedures is not reported in the registry record.

General: count outcomes. The primary outcome is a count of participants achieving CR or CRi, and the safety entries also use counts of participants affected by events. A count answers how many people met a definition; it is distinct from an event rate over person-time or a time-to-event estimate. A count alone does not show the proportion of all eligible participants unless its denominator is clear. The registry lists 32 participants at risk in the safety group, but does not report the number included in the primary remission analysis or the primary remission count.

General: uncertainty and confidence intervals. A confidence interval is a way of expressing the statistical uncertainty around an estimate. It can show a range of values compatible with the data under the method used, rather than presenting a single estimate as exact. No confidence interval is reported for the primary remission outcome or the posted safety figures. No inferential results are reported, so the precision of an estimated remission frequency cannot be evaluated from the registry record. An interval, if available, would not by itself remove limitations due to retrospective data collection or the absence of a comparator.

General: comparison and confounding. A randomized comparison aims to make treatment groups comparable in expectation, whereas this record describes one InO-treated group and does not state allocation to groups. In an observational cohort, participant characteristics and prior treatment can be related both to treatment received and to outcomes. This can make a treatment comparison difficult to interpret even when statistical adjustment is used. No comparator is described, and any adjustment model or covariate set is not reported in the registry record. There is therefore no posted treatment contrast to interpret, adjusted or otherwise.

General: over-dispersion. Over-dispersion arises when observed variation in count data is greater than expected under a statistical model that assumes a particular level of variability. It can affect standard errors and uncertainty estimates if a model does not account for that extra variation. The registry record does not report a model for the primary count outcome, a dispersion assessment, or an inferential analysis. Over-dispersion is thus a general consideration for count modelling, not a reported finding about this study.

General: time-to-event outcomes. Duration of remission is listed among the secondary outcomes. Time-to-event methods can account for differing follow-up lengths and for participants whose event has not occurred by the end of observation, if the relevant event and censoring rules are specified. The registry record does not report a duration-of-remission result, an estimator, a censoring definition, or a model. These methods cannot be attributed to this analysis on the available information.

General: analyses and multiplicity. The registry lists 28 outcome measures and zero analyses. When many outcomes or subgroup questions are examined, the chance of finding apparently notable results by chance can increase; multiplicity procedures are sometimes used to address this issue. The record does not report whether multiplicity was considered, whether outcomes were prioritized beyond identifying a primary outcome, or whether subgroup analyses were prespecified. It is not possible to infer an analysis plan from the list of outcomes alone.

General: sample size and power. A planned sample size can be chosen to achieve a target probability of detecting an effect under stated assumptions. Such planning is not the same as evidence that an effect was observed, and observed sample size alone does not establish power. The registry lists enrollment of 32 and says around 55 patients were likely to be enrolled in the study description. A sample-size justification, target power, assumed effect, and statistical planning method are not reported in the registry record. The enrollment figure should therefore be read as a record of enrollment, not as proof that a particular level of precision or power was achieved.

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("Inotuzumab Ozogamicin (InO)")
n      <- c(32)
events <- c(19)
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  Inotuzumab Ozogamicin (InO)  32  19  59.4  40.6  76.3  42.3  74.5  42.1  74.5

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 28 outcome measures, including the primary CR/CRi count and secondary outcomes concerning MRD negativity, treatment cycles, and duration of remission. It lists zero analyses. No results for these outcomes, subgroup estimates, or inferential tests are reported in the registry record. The presence of multiple listed outcomes does not establish that every outcome was analyzed or that any particular analysis was planned.

As a general statistical issue, testing or estimating many outcomes can make isolated findings harder to interpret. A study may address this through a prespecified hierarchy, adjusted significance thresholds, or other multiplicity procedures. Whether any such approach was used is not reported in the registry record. The registry does not report interim analyses or a detailed statistical plan, and those details should not be inferred from the outcome list.

The analysis population is described as all eligible participants whose data were retrieved and observed. The number meeting that description, the amount of missing data, the handling of incomplete records, and any imputation methods are not reported in the registry record. The stated enrollment of 32 does not by itself establish how many participants contributed to each outcome. This is particularly relevant to the primary endpoint because the remission count and its denominator are not posted.

As a general principle, missing records or outcome values can affect both the denominator and the interpretation of a count. Transparent reporting of exclusions, missingness, and outcome-specific denominators helps readers understand which observations support a result. Those details are not reported for this analysis.

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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: death (53.1%), veno occlusive disease (vod) (21.9%).

The InO group lists 32 participants at risk for serious adverse events, with 19 affected. For other adverse events, 32 participants are listed at risk and 28 affected. The registry separately lists 17 deaths. The serious adverse event terms with the largest listed percentages are Death at 53.1% and Veno Occlusive Disease (VOD) at 21.9%.

These entries describe events recorded in the study group; they do not establish that InO caused an event. The registry record does not report an untreated or alternative-treatment comparator, detailed event timing, or the assessment of relatedness to InO. It also does not report whether the same participant could contribute to more than one event category. Counts for serious and other adverse events should therefore not be treated as mutually exclusive groups unless the record establishes that they are.

The listed term percentages are registry entries, not evidence of a comparative risk. Without further information about event definitions, ascertainment, follow-up, and attribution, the figures should be read as descriptive safety reporting for the recorded cohort. They cannot establish a treatment-specific risk or support a comparison with another treatment.

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

The registry record establishes that a completed retrospective study of InO use in adults with relapsed or refractory B-cell ALL was registered, with enrollment of 32 participants. It specifies a primary outcome combining CR and CRi and lists safety counts for the InO group. It also identifies secondary questions concerning MRD negativity, treatment cycles, and duration of remission.

The record does not report the primary remission count or any analyses. As a result, it does not show how many participants achieved CR or CRi, how precise such an estimate might be, or whether any statistical comparison was made. The listed outcome definition cannot substitute for an outcome result. Similarly, the secondary outcome titles are not numerical findings.

The safety entries are descriptive counts and listed terms. They do not establish causation, because the registry does not report event attribution or a comparison group. They also cannot be used to estimate a comparative safety difference. The record provides no randomized control group and does not report an adjusted comparison.

As a general interpretation principle, findings from a retrospective cohort apply most directly to the records and participants included in that analysis. Selection into the cohort, completeness of medical records, and differences in prior treatment can limit how broadly results can be applied. Here, the analyzed participant count, missing-data handling, and detailed analysis methods are not reported in the registry record. The enrollment figure alone does not resolve those uncertainties.

Accordingly, the posted information supports a description of the study’s question, design, and certain safety entries, but not a conclusion about the frequency of remission or the comparative effects of InO. The data shown in the registry record should not be interpreted as demonstrating that treatment does or does not work.

14. Why This Trial Matters Statistically

Retrospective treatment records can describe clinical outcomes and safety events in a patient group encountered in routine care. For biostatistical interpretation, however, the value of such a description depends on clear outcome definitions, an identifiable analysis population, appropriate denominators, and transparent reporting of uncertainty. This study’s registry entry defines CR and CRi and identifies the intended primary count, which clarifies what the principal outcome was meant to capture.

The entry also illustrates why registration information and posted results must be distinguished. A defined endpoint and a completed status do not provide the endpoint result. Although the registry lists 28 outcome measures, it lists zero analyses and does not report the primary remission count. Readers therefore cannot assess the study’s main outcome estimate or its precision from the registry record.

Safety reporting also benefits from careful statistical reading. The listed counts and event terms describe what was recorded in the InO group, but no comparator or causality assessment is reported. Treating these entries as comparative risks would go beyond the information in the record.

The stated enrollment of 32 and the brief summary’s expectation of around 55 highlight another reporting issue: readers need to know which number represents the enrolled cohort and how many participants contributed to each outcome. The analyzed number and outcome-specific denominators are not reported. These details are essential for interpreting descriptive counts and for understanding whether the observed records represent the intended population.

Statistically, the record is informative about the questions the study set out to address, but incomplete for assessing answers to those questions. The absence of posted estimates, uncertainty measures, analysis details, and a comparator sharply limits what can be concluded from the registry entry.

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 most direct limitation is that the registry record does not report the primary outcome result. Although it defines CR and CRi and names the count of participants achieving either outcome, it gives no remission count or primary-outcome estimate. It also lists zero analyses. The listed secondary outcomes do not have posted numerical results.

The study is retrospective and based on hospital electronic medical records in India. The registry does not report how participants or hospitals were selected, how records were reviewed, how missing or conflicting data were handled, or how many participants met the analysis-population definition. The enrollment entry is 32, while the study description says around 55 patients were likely to be enrolled; the reason for this difference is not reported in the registry record.

No comparator group is described, and treatment allocation is not stated. The posted information therefore cannot separate treatment-associated outcomes from differences in patient characteristics, prior therapy, follow-up, or record completeness. No confidence intervals, p-values, adjusted estimates, or statistical-analysis plan are reported. The registry also does not report whether multiplicity was addressed or whether any interim analyses occurred.

For safety, the record lists counts and event terms but does not report event timing, attribution to InO, or whether participants could appear in multiple categories. These entries cannot be treated as evidence of causal or comparative risk. Finally, the timeframe covers treatment initiation from Apr 2018 through follow-up ending in Apr 2023, with maximum follow-up of up to 61 Months; individual follow-up completeness and censoring details are not reported.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of Patients Who Received Inotuzumab Ozogamicin for B-cell ALL (Acute Lymphoblastic Leukemia) That Occurred Again After the Last Treatment — NCT05597085.
• Registry record last updated 2025-02-04; status last verified 2025-01.
• Results first posted 2025-02-04.
• 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

NCT05597085 is a completed retrospective analysis of Inotuzumab Ozogamicin use in adults with relapsed or refractory B-cell ALL. The registry lists enrollment of 32, a start date of 2023-03-08, and primary completion on 2023-07-10. The study description concerns hospital electronic medical records in India and InO treatment alone.

The primary outcome is the count of participants achieving CR or CRi following InO. The registry describes the remission definitions and timeframe but does not report the primary count. It lists 28 outcome measures and zero analyses. Safety entries include 19 participants affected by serious adverse events, 28 affected by other adverse events, and 17 deaths, among 32 listed at risk in each category. These are descriptive entries; no comparator or causal attribution is reported.

The analysis-population size, missing-data handling, statistical plan, and numerical results for the primary and secondary outcomes are not reported in the registry record.