This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for A Study of the Effect of Blood Stem Cell Transplant After Chemotherapy Alone in Patients With Fanconi Anemia (NCT03600909), a non-randomized phase 2 study. The primary outcome is Graft Failure or Rejection.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03600909 |
| Phase | Phase 2 |
| Condition | Fanconi Anemia, Myelodysplastic Syndrome (MDS), Acute Myelogenous Leukemia (AML) |
| Allocation | Non-Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 3 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Memorial Sloan Kettering Cancer Center |
| Results posted | Yes |
2. Clinical Question
The study asked whether a chemotherapy-only conditioning approach before hematopoietic stem cell transplantation could reduce chemotherapy-related side effects while maintaining disease control in patients with Fanconi anemia who lacked a genotypically identical donor. It also planned to study donor T-cell removal through CD34 selection using the CliniMACS device, because T-cells may contribute to graft-versus-host disease.
Population
Patients with Fanconi anemia were the focus. The registry also lists myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML) as conditions. Risk groups were defined by age and disease status: patients 18 years old or younger with marrow aplasia or single lineage cytopenias were in the good-risk group; patients 18 years old or younger with MDS or AML were in the intermediate-risk group; and patients 19 years old or older with marrow aplasia, MDS or AML were in the high-risk group.
Intervention
The planned treatment involved transplantation after risk-adjusted chemotherapy conditioning with busulfan, cyclophosphamide and fludarabine. The record also lists rabbit anti-thymocyte globulin, the CliniMACS device and G-CSF as interventions. The device was intended for CD34 selection of donor stem cells.
Comparator
The registry describes a non-randomized, parallel-group study without masking. The risk groups reflect different patient characteristics and conditioning regimens; they are not a like-for-like control comparison. The registry record does not report a separate untreated or standard-treatment comparator.
Primary question
The primary endpoint was graft failure or rejection through 5 years. The study planned to assess whether transplantation could be carried out with the intended balance of disease control and chemotherapy-related side effects, but no participants received treatment and no efficacy result was collected.
3. Trial Design
This was a Phase II, non-randomized, open-label, parallel-group trial sponsored by Memorial Sloan Kettering Cancer Center. It was designed for patients with Fanconi anemia lacking a genotypically identical donor. Its protocol description assigns conditioning regimens according to risk categories rather than randomly assigning participants to comparable treatment arms. Therefore, comparisons between those categories would not isolate treatment effects: age and disease status differ by the stated group definitions, and the planned busulfan dose also differs.
For good-risk patients, defined as patients 18 years old or younger with marrow aplasia or single lineage cytopenias, the planned regimen included intravenous busulfan at 0.6-0.8 mg/Kg/dose q 12 hours x 4 doses, cyclophosphamide at 10 mg/Kg/dose x 4 doses and fludarabine at 35mg/m2/day x 4 doses. Intermediate-risk patients were 18 years old or younger with MDS or AML; their planned busulfan dose was 0.8-1.0mg/Kg/dose q 12 hours x 4 doses, with the same stated cyclophosphamide and fludarabine schedules. High-risk patients were 19 years old or older with marrow aplasia, MDS or AML; their planned busulfan dose was 0.4mg/Kg/dose q 12 hours x 4 doses, with the same stated cyclophosphamide and fludarabine schedules.
The registry lists enrollment as 3, but also states that no participants received treatment and that the study was terminated due to slow accrual. The primary completion date was 2021-04-09, and the recorded start date was 2018-05-15. Treatment exposure and primary endpoint data were not collected. The record does not report why enrollment reached the recorded number but treatment did not occur, so that distinction should not be interpreted beyond the registry statements.
Although the trial was intended to investigate treatment and transplant-related outcomes, its final registry record cannot support an efficacy comparison. It contains no treatment outcomes, and its risk groups were not randomized control groups. The planned design and the observed record must therefore be kept separate: the former describes what investigators intended to study, while the latter indicates that treatment and outcome data are absent.
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
| Stage | Good Risk Patients | Intermediate Risk Patients | High Risk Patients |
|---|---|---|---|
| STARTED | 0 | 3 | 0 |
| COMPLETED | 0 | 0 | 0 |
| NOT COMPLETED | 0 | 3 | 0 |
Reasons for not completing this period:
| Reason | Good Risk Patients | Intermediate Risk Patients | High Risk Patients |
|---|---|---|---|
| Not treated | 0 | 3 | 0 |
Analysis population for the primary outcome, as defined in the registry: Data were not collected. No participants received treatment and study terminated due to slow accrual
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: Study closed due to slow accrual
| Characteristic | Unit | Good Risk Patients | Intermediate Risk Patients | High Risk Patients | Total |
|---|---|---|---|---|---|
| Participants analysed | 0 | 3 | 0 | 3 | |
| Age, Continuous | years | — | 18 (7 to 24) | — | 18 (7 to 24) |
| Sex: Female, Male: Female | Participants | — | 2 | — | 2 |
| Sex: Female, Male: Male | Participants | — | 1 | — | 1 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | — | 0 | — | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | — | 3 | — | 3 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | — | 0 | — | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | — | 0 | — | 0 |
| Race (NIH/OMB): Asian | Participants | — | 2 | — | 2 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | — | 0 | — | 0 |
| Race (NIH/OMB): Black or African American | Participants | — | 0 | — | 0 |
| Race (NIH/OMB): White | Participants | — | 1 | — | 1 |
| Race (NIH/OMB): More than one race | Participants | — | 0 | — | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | — | 0 | — | 0 |
| Region of Enrollment: United States | Participants | — | 3 | — | 3 |
6. Primary Endpoint
The registry lists the primary outcome as Graft Failure or Rejection, measured over 5 years.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was graft failure or rejection, with a timeframe of 5 years. It was intended to capture whether donor stem cells established and maintained the expected blood-forming function after transplantation. This is relevant to a transplant study because graft establishment is a central feature of the planned procedure; however, the endpoint’s clinical importance does not create evidence about its frequency when no treated participants were observed.
The registry defines primary non-engraftment as failure to achieve an ANC ≥500/µl at any time in the first 28 days after transplant. It defines secondary graft failure in either of two circumstances: after an ANC ≥500/mm^3 has been achieved, the ANC falls to <500/mm^3 for more than 3 consecutive days in the absence of relapse; or donor cells are absent in marrow and/or blood as demonstrated by a chimerism assay, also in the absence of relapse. A patient is not evaluable for graft failure or rejection if recurrence of host MDS is detected concurrently.
These definitions specify how the endpoint was intended to be identified, but the registry says data were not collected. Thus there is no observed endpoint count, rate, or time-to-event estimate to interpret. The endpoint definition describes the planned measurement, not an outcome finding.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical fact is that the registry reports no treatment exposure and no collected data for the primary endpoint. As a result, there is no observed graft failure or rejection result to estimate, no treatment effect to compare, and no uncertainty interval around a clinical outcome. The enrollment entry of 3 does not change that conclusion: enrollment is not the same as receiving the study treatment, and the registry explicitly says no participants received treatment.
The registry lists the study as terminated due to slow accrual. It also records zero affected serious and other adverse events for the intermediate-risk group, where 3 were listed at risk. The good-risk and high-risk groups each have zero listed at risk and zero affected. These are safety-record entries, not outcome estimates from a treated study population. They cannot establish the safety profile of the planned conditioning regimen or transplant procedure, particularly when the registry says no one received treatment.
The non-randomized design also matters to interpretation. The three risk categories were defined using age and disease characteristics, and the planned conditioning regimens varied across categories. Even if outcomes had been collected, differences among those groups would not by themselves constitute a randomized comparison of treatment strategies. In the registry record, there are no outcome data with which to make such comparisons in any case.
The record’s objective was to assess chemotherapy-related side effects and disease control, and to study T-cell removal by CD34 selection. Those remain the stated aims, not demonstrated results. No estimates of disease control, graft success, graft-versus-host disease, treatment-related toxicity, or survival are reported in the registry record. The record also does not report a statistical analysis of the primary endpoint.
Any planning illustration based on a fraction of an observed effect should be read as a hypothetical design calculation, not as evidence that an effect was observed in this study or as observed power. The posted record contains no primary endpoint result from treated participants on which to base a clinical interpretation. It supports a description of the planned design, its endpoint definitions, and its termination, but not a conclusion about whether the intervention altered outcomes.
9. Statistical Methods Explained
The registry identifies a Phase II, non-randomized, parallel-group study with no masking. These design labels describe how the trial was organized; they do not themselves state which statistical model or inferential test was used. The registry record does not report a statistical analysis plan, an analysis method for the primary endpoint, an adjusted estimate, a confidence interval, or a hypothesis test. There are also no primary endpoint data because the record says data were not collected.
What does non-randomized mean for interpretation?
General statistical explanation: random allocation is used to make treatment groups comparable, on average, with respect to both measured and unmeasured characteristics. In a non-randomized design, group membership may reflect participant characteristics or clinical decisions. This can make a difference between groups difficult to attribute to treatment. In this trial, the groups were defined by age and disease status and were assigned different planned busulfan schedules. Thus they are risk categories, not interchangeable treatment arms or a randomized control comparison. The record’s stated allocation and group descriptions support that distinction; they do not report an adjustment method intended to address it.
What would a confidence interval communicate?
General statistical explanation: a confidence interval expresses the precision of an estimate under a specified statistical method. A narrower interval generally indicates greater precision, while a wider interval indicates more uncertainty. It does not correct for bias in study design, and it cannot substitute for the outcome data needed to calculate an estimate. No confidence interval for graft failure or rejection is reported in the registry record, because no participants received treatment and no endpoint data were collected.
Why can small or absent outcome data be limiting?
General statistical explanation: the information available for estimating an outcome depends on the observations relevant to that outcome, not only on a study’s enrollment field. When no treated participants contribute endpoint observations, a treatment outcome cannot be estimated. Even when some observations exist, limited information can produce imprecise estimates; however, no precision estimate can be derived for this primary endpoint from the registry record. It would be inappropriate to treat the enrollment entry as if it were a treated analysis population.
What does over-dispersion mean?
General statistical explanation: over-dispersion occurs when outcome variability is greater than a statistical model assumes. It can affect standard errors and the reliability of tests or intervals if the model does not account for the extra variability. The registry record does not report a count model, an over-dispersion assessment, or any fitted model for the primary endpoint. Since outcome data were not collected, there is no basis to evaluate over-dispersion for this study.
How should sample-size illustrations be understood?
The record describes planning illustrations based on an observed effect, a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation. It says that the effect to detect is a stated fraction of the observed effect; time-to-event illustrations use a total number of events, while other illustrations are expressed as participants per arm. These are general planning assumptions, not a report of the trial’s own design justification. The registry record does not report a sample-size justification or its own statistical plan. More importantly, no treated participants contributed a primary outcome, so an observed treatment effect is not available from this trial record. Such illustrations must not be called observed power or interpreted as a clinical finding.
General statistical explanation: power is a prospective design quantity that depends on assumptions about the effect, variability, allocation and analysis. It is not a measure of how likely a particular study result is true after the fact. A sample-size calculation can illustrate what a future design might require under stated assumptions, but it cannot recover missing observations or establish efficacy. No new estimate can be inferred from the registry’s design labels or endpoint criteria.
In short, the statistical methods that can be described are limited to the registry’s design labels and the stated assumptions for planning illustrations. The record does not report inferential analyses, treatment-effect estimates, confidence intervals, or model diagnostics. This absence should be distinguished from a finding of no effect: without collected outcome data, the effect is unknown in this record.
10. Multiplicity, Missing Data and Analysis Populations
The registry record does not report a statistical analysis plan describing how multiple outcomes or comparisons would be handled. It identifies one primary outcome measure, graft failure or rejection, but a count of outcome measures does not establish that there were no secondary or exploratory questions. The record’s stated aims also include chemotherapy-related side effects, disease control and the effect of donor T-cell removal, yet no multiplicity procedure or hierarchy for testing those aims is reported. It is therefore not possible to determine whether any planned multiplicity adjustment would have been used.
The primary endpoint’s registry description says data were not collected because no participants received treatment and the study terminated due to slow accrual. Consequently, there is no endpoint analysis population, no reported exclusion flow, and no analysis of missing endpoint observations. The registry does not report imputation, censoring rules beyond the endpoint definition, sensitivity analyses, or a method for handling missing data. Since the outcome data were not collected, it would be misleading to characterize the situation as ordinary participant-level missingness or to assume that missing values were analyzed using a particular method.
The record does not state whether an intention-to-treat, per-protocol, safety, or other analysis population was specified for efficacy analyses. The enrollment field records 3, while the registry separately states that no participants received treatment. These statements describe different aspects of the record and should not be conflated into a treated efficacy sample. No interim analysis, stopping boundary, or formal early-stopping rule is reported. The stated termination reason is slow accrual; the registry does not report additional statistical criteria for termination.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Intermediate Risk Patients | 0 | 3 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Good Risk Patients | 0 of 0 |
| Intermediate Risk Patients | 0 of 3 |
| High Risk Patients | 0 of 0 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Good Risk Patients | 0 of 0 |
| Intermediate Risk Patients | 0 of 3 |
| High Risk Patients | 0 of 0 |
The adverse-event entries should be read as registry counts, not as proof that the planned treatment was free of adverse effects. In the intermediate-risk group, 3 were listed at risk for serious adverse events and 3 at risk for other adverse events; none were listed as affected in either category, and deaths were recorded as 0. The good-risk and high-risk groups each had 0 listed at risk, with 0 affected and 0 deaths recorded.
The crucial context is that the registry states that no participants received treatment. Therefore, the zero affected counts do not describe observed safety among participants exposed to the conditioning regimen or transplant. Groups with no one listed at risk cannot provide evidence about event frequency, and the intermediate-risk entries do not establish a safety rate for treatment exposure. The record lists no top serious adverse-event terms. That absence should be interpreted as a feature of the posted safety record, not as evidence that no clinically important harms would occur under treatment.
The counts are also not a substitute for the primary endpoint, which concerns graft failure or rejection. The registry provides no treated-patient safety analysis or collected outcome dataset from which to assess timing, duration, severity patterns, or relationships to treatment.
12. What the Result Does, and Does Not, Mean
The registry record establishes what investigators planned to study: risk-adjusted chemotherapy conditioning before hematopoietic stem cell transplantation in patients with Fanconi anemia lacking a genotypically identical donor, together with CD34 selection of donor cells. It also records a primary endpoint definition for graft failure or rejection and a planned timeframe of 5 years. These details clarify the intended clinical question and how a key outcome would have been assessed.
The record does not establish whether the treatment achieved disease control, reduced chemotherapy-related side effects, changed graft failure risk, or affected graft-versus-host disease. No participants received treatment, and data for the primary endpoint were not collected. As a result, no effect estimate or uncertainty measure is available. The absence of an observed result is not evidence that the treatment has no effect; it means this registry record cannot answer the treatment-effect question.
Nor can the registry’s adverse-event entries establish that the intervention is safe. The at-risk counts and affected-event counts must be interpreted alongside the statement that no treatment was given. Zero recorded events in that context is not an estimate of the risk under exposure.
The non-randomized, risk-stratified design would also require care in interpreting comparisons across the planned groups. They differ in age and disease characteristics, and the planned busulfan regimens differ. They are not randomized, like-for-like controls. Even complete results from such groups would not automatically identify a causal effect of one regimen versus another.
The most defensible conclusion is therefore about the registry record, not clinical performance: the study was terminated due to slow accrual, and it reports no treatment outcome data. The trial’s aims and endpoint criteria are informative about its intended design, but they do not support a conclusion that the planned approach was effective, ineffective, safe, or unsafe.
13. Why This Trial Matters Statistically
This trial matters statistically because it illustrates the difference between a protocol question and an answer supported by observed data. A clearly defined endpoint and treatment plan can establish what investigators intended to measure, but neither can produce an estimate when no participants receive treatment and no endpoint observations are collected. In this record, the primary outcome is specified in detail, yet there is no result to quantify.
It also demonstrates why enrollment and outcome information should be read separately. The registry lists enrollment as 3, while explicitly stating that no participants received treatment. An enrollment entry cannot be treated as an efficacy denominator or as evidence of exposure. Likewise, zero adverse events among recorded at-risk entries do not provide a treatment safety estimate when the record says treatment did not occur.
The risk-based regimen illustrates a further design issue. The groups were defined by age and disease status, with distinct planned busulfan doses. Differences across them would be difficult to interpret as treatment effects because patient characteristics and regimen assignment vary together. The non-randomized design does not create a like-for-like control comparison.
Finally, planning calculations and trial results answer different questions. A planning illustration can express hypothetical sample requirements under assumptions, but cannot compensate for absent outcome data or establish observed power. The record therefore offers a useful lesson in evidential limits: detailed methods and clinically important aims do not remove uncertainty when the study yields no treated outcome data.
14. 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 important trial-specific limitation is that the registry states no participants received treatment and that data were not collected for the primary endpoint. Consequently, there is no observed graft failure or rejection result, and the record cannot estimate treatment effects or endpoint precision. Although enrollment is recorded as 3, that entry does not indicate treatment exposure.
The study was terminated due to slow accrual. The registry does not report further details about the accrual problem, any modifications to recruitment, or whether the planned design changed before termination. The reason for termination should not be extended into an assumption about the treatment or its anticipated performance.
The design was non-randomized, and the risk groups had different eligibility characteristics and planned busulfan regimens. They cannot be treated as equivalent controls. The record does not report a comparator group receiving another treatment, an adjustment strategy for group differences, or a statistical method for comparing the groups.
The registry does not report an analysis plan, a sample-size justification, interim analyses, or procedures for multiplicity. It also does not report an efficacy analysis population, a method for handling missing outcomes, or estimates for the additional stated aims concerning side effects, disease control and CD34 selection. The absence of these details in the registry record should not be filled by assumptions about the protocol.
Finally, safety entries are not interpretable as treatment-exposure results in the context of no treatment. They cannot establish the frequency of adverse events under the planned transplant regimen. Together, these limitations mean that the record documents an intended study and its termination, but does not provide clinical outcome evidence for the intervention.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study of the Effect of Blood Stem Cell Transplant After Chemotherapy Alone in Patients With Fanconi Anemia — NCT03600909.
- Registry record last updated 2022-04-12; status last verified 2021-04.
- Results first posted 2022-04-12.
- 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.
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18. Record Summary
The registry describes a Phase II, non-randomized, open-label, parallel-group study of risk-adjusted chemotherapy conditioning before hematopoietic stem cell transplantation for patients with Fanconi anemia lacking a genotypically identical donor. The planned regimen included busulfan, cyclophosphamide and fludarabine, with CD34 selection using the CliniMACS device also described. The primary endpoint was graft failure or rejection through 5 years.
The recorded enrollment is 3. The registry states that no participants received treatment, that primary endpoint data were not collected, and that the study was terminated due to slow accrual. No treatment-effect analysis or outcome estimate is reported. The posted adverse-event counts do not establish safety under treatment exposure. The record therefore documents the study’s intended design and endpoint, but cannot answer whether the planned intervention changed clinical outcomes.