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 Immunotherapy With or Without Radiation Therapy for Metastatic Urothelial Cancer (NCT04936230), a randomized phase 2 study. The primary outcome is Tumor Response.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04936230 |
| Phase | Phase 2 |
| Condition | Metastatic Urothelial Carcinoma, Platinum-Resistant Urothelial Carcinoma, Stage IV Bladder Cancer AJCC v8 |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 1 |
| Arms in the primary outcome | n/a |
| Lead sponsor | National Cancer Institute (NCI) |
| Results posted | Yes |
2. Clinical Question
Population
Patients with platinum-ineligible or platinum-refractory metastatic urothelial cancer. The registry record reports enrollment of 1 participant; the primary outcome population is withheld to maintain deidentification.
Intervention
Pembrolizumab together with stereotactic body radiation therapy (SBRT). The arm description says SBRT was planned every other day for 3 fractions over 2 weeks, with completion before 12 weeks after the first pembrolizumab dose, absent progression or unacceptable toxicity.
Comparator
Pembrolizumab alone. The arm description specifies administration by intravenous infusion on day 1 of each cycle, with cycles repeating every 3 weeks absent progression or unacceptable toxicity.
Primary question
Does adding SBRT to pembrolizumab change the proportion of participants with complete or partial tumor response, assessed by the treating physician using RECIST version 1.1 up to 6 months from randomization? The registry record does not share the response result.
3. Trial Design
This was a randomized, parallel-group phase II trial of pembrolizumab with or without radiation therapy for metastatic urothelial cancer in patients described as platinum-ineligible or platinum-refractory. The trial record identifies the sponsor as the National Cancer Institute (NCI). Masking is listed as none, so the design was open-label. The registry record does not report the randomization ratio or further details of sequence generation or allocation concealment.
Arm A received pembrolizumab. The registry describes an intravenous infusion on day 1 of each cycle, with cycles repeating every 3 weeks in the absence of disease progression or unacceptable toxicity. Arm B received pembrolizumab as in Arm A, with SBRT added. The SBRT schedule is described as every other day for 3 fractions over 2 weeks and was to be completed before 12 weeks after the first pembrolizumab dose, absent progression or unacceptable toxicity. Imaging and sample-collection procedures are also listed, though the registry’s arm descriptions do not provide a complete account of all procedures.
The registry record lists enrollment of 1 and gives the status as terminated. It records a start date of 2022-11-22 and a primary completion date of 2024-08-15. The reason for termination and the treatment assignment of the participant are not reported in the registry record. These design features describe the intended comparison, but the small reported enrollment and unavailable primary outcome prevent an interpretable comparison of response between the arms.
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 | Arm A (Pembrolizumab) | Arm B (Pembrolizumab, SBRT) |
|---|---|---|
| STARTED | 1 | 0 |
| COMPLETED | 1 | 0 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: In order to maintain the deidentification of the 1 patient accrued, this outcome measure will not be shared.
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: In order to maintain the deidentification of the 1 patient accrued, the patient demographics will not be shared.
| Characteristic | Unit | Arm A (Pembrolizumab) | Arm B (Pembrolizumab, SBRT) | Total |
|---|---|---|---|---|
| Participants analysed | 0 | 0 | 0 | |
| Sex: Female, Male: Female | — | — | — | |
| Sex: Female, Male: Male | — | — | — | |
| Ethnicity (NIH/OMB): Hispanic or Latino | — | — | — | |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | — | — | — | |
| Ethnicity (NIH/OMB): Unknown or Not Reported | — | — | — | |
| Race (NIH/OMB): American Indian or Alaska Native | — | — | — | |
| Race (NIH/OMB): Asian | — | — | — | |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | — | — | — | |
| Race (NIH/OMB): Black or African American | — | — | — | |
| Race (NIH/OMB): White | — | — | — | |
| Race (NIH/OMB): More than one race | — | — | — | |
| Race (NIH/OMB): Unknown or Not Reported | — | — | — |
6. Primary Endpoint
The registry lists the primary outcome as Tumor Response, measured over Up to 6 months from randomization.
| 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 is tumor response, defined as complete response (CR) or partial response (PR) assessed by the treating physician using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. The specified assessment period is up to 6 months from randomization. In general, a response endpoint classifies whether a tumor meets prespecified criteria for a reduction or disappearance of measurable disease. Combining complete and partial response into a response category can provide a way to describe tumor shrinkage across participants.
RECIST is a standardized framework for defining and assessing tumor response. Using stated criteria can make response classification more consistent than relying on an informal description alone, although assessment still depends on the available scans and the evaluation process. The registry record does not describe further assessment procedures, the timing or frequency of imaging, or how response data were to be handled if unavailable.
The outcome value and its participant-level distribution are not reported in the registry record. The record states that the result will not be shared in order to maintain the deidentification of the 1 participant accrued. Consequently, the endpoint definition is available, but no response estimate or comparison between treatment groups can be interpreted from the posted results.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry describes a randomized comparison of pembrolizumab alone against pembrolizumab plus SBRT, with tumor response as the primary outcome. It does not provide the primary response result. The stated reason is to maintain the deidentification of the 1 participant accrued. As a result, the posted record does not support an estimate of response in either arm or an estimate of the difference between arms.
There are no inferential analyses reported in the registry record. The primary outcome is not reducible to a reported comparison in the posted results, and the record does not give a response count, percentage, effect estimate, confidence interval, or p-value. None should be inferred from enrollment or from the study’s intended design. The record also does not identify which arm received the participant, so even a description of arm-specific enrollment is unavailable.
The status is listed as terminated, but the reason for termination is not reported in the registry record. Termination alone does not establish why the study ended or what happened to the participant’s treatment or follow-up. The listed primary completion date is 2024-08-15, but that date does not supply the missing outcome data or establish that the planned comparison was completed.
In general, an effect estimate describes the size and direction of a comparison, while a confidence interval describes the range of values compatible with the data under the analysis assumptions. Neither can be assessed without a reported estimate and underlying information. A p-value, if one were reported, would address compatibility with a specified null model; it would not by itself describe the magnitude or precision of an effect. The registry record reports no such results.
The trial’s randomized structure describes an intended basis for comparing the arms, but randomization cannot compensate for an unavailable endpoint result. With enrollment of 1 and no response result shared, the posted record provides no empirical basis for concluding whether the response outcome differed between the assigned approaches. This is a limitation of what can be interpreted from the registry record, not evidence for or against either treatment approach.
9. Statistical Methods Explained
The record identifies a randomized, parallel-group phase II design with no masking. The intended arms were pembrolizumab alone and pembrolizumab with SBRT. Randomization is a general method for assigning participants to treatment groups by chance. When implemented as planned, it can reduce systematic differences between groups at baseline, but it does not guarantee that groups will be alike, particularly when enrollment is very small. The registry record does not describe the randomization procedure or the allocation ratio.
What does an open-label design mean?
In general, an open-label design means treatment assignment is not masked from participants or study personnel. The registry lists masking as none. Knowledge of assignment can affect aspects of study conduct or assessment, so objective definitions and consistent measurement procedures are important. The primary outcome was to be assessed by the treating physician using RECIST version 1.1. The record does not report additional safeguards for response assessment, such as independent review.
How is tumor response defined?
The primary outcome combines complete response and partial response, as assessed by the treating physician using RECIST version 1.1, up to 6 months from randomization. In general, a prespecified response definition makes the outcome rule explicit: participants are classified according to whether their disease meets criteria for a response during the stated assessment period. This definition alone does not show how many participants responded. Here, the registry withholds the outcome result for deidentification, so no response estimate is available.
What would an arm comparison estimate?
In general, an analysis comparing randomized arms would summarize the outcome in each arm and estimate the contrast between them according to a stated statistical plan. For a binary response outcome, results could be expressed using counts and proportions or a comparative effect measure, with uncertainty described by a confidence interval. These are general approaches, not a description of an analysis reported for this trial. The registry record contains no analyses and does not report a response count, comparative estimate, confidence interval, or p-value.
What does a confidence interval communicate?
In general, a confidence interval represents uncertainty around an estimated quantity under the assumptions of the method used. Wider intervals indicate less precision than narrower intervals, all else equal. An interval is not a guarantee that the true value lies within its endpoints, and its interpretation depends on the analysis and data. No confidence interval is reported for this trial’s primary outcome, so the precision of any treatment comparison cannot be assessed.
How should planning illustrations be understood?
In general, sample-size planning explores how many participants or events might be needed to detect a specified effect under chosen assumptions. A planning value is not an observed result and does not establish the power of a completed trial. The registry record describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; it also specifies that time-to-event illustrations use total events, while other illustrations use participants per arm. However, the primary outcome is not reduced to one comparison, and no analyses are reported. No usable trial-specific effect estimate or numerical planning result is reported in the registry record. These planning assumptions therefore do not supply evidence about treatment effects.
What can be inferred from the posted analysis record?
The record lists six outcome measures and zero analyses. It identifies tumor response as the primary outcome and lists tumor response, progression-free survival, overall survival, rate of treatment discontinuation, and incidence of adverse events among secondary outcomes. The registry record does not provide an analysis population, statistical model, adjustment strategy, or outcome estimates. General statistical methods cannot fill those gaps: a method requires data and a defined analysis to produce an interpretable estimate. The primary response result is explicitly withheld, and the remaining posted information does not permit reconstruction of arm comparisons.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists tumor response as the primary outcome and names secondary outcomes that include progression-free survival, overall survival, rate of treatment discontinuation, and incidence of adverse events. It does not report a multiplicity strategy. In general, when several outcomes or comparisons are examined, multiplicity procedures may be used to address the increased chance of false-positive findings across tests. Without a stated analysis plan and reported tests, the implications of multiple outcomes cannot be assessed. No claim about adjustment or unadjusted testing is supported by the registry record.
Missing-data methods and the handling of participants without an evaluable response are not reported in the registry record. The primary outcome result is withheld to maintain deidentification of the 1 participant accrued. That disclosure does not indicate whether the outcome was measured, why it was withheld beyond the stated privacy reason, or how any unavailable measurements would have been handled in an analysis.
The analysis populations are not reported in the registry record. It does not say whether an intention-to-treat, per-protocol, or other population was planned for the primary analysis. The record also does not describe an interim analysis plan, a statistical analysis plan, or a method for handling protocol deviations. These omissions prevent assessment of how the planned analysis might have treated missing assessments, departures from assigned treatment, or multiple endpoints.
11. What the Result Does, and Does Not, Mean
The posted record establishes that a randomized phase II trial was intended to compare pembrolizumab alone with pembrolizumab plus SBRT for platinum-ineligible or platinum-refractory metastatic urothelial cancer. It defines tumor response as complete or partial response under RECIST version 1.1, assessed by the treating physician up to 6 months from randomization. Those details describe the research question and outcome definition, not the result.
The record reports enrollment of 1 and says the primary outcome will not be shared in order to maintain participant deidentification. It therefore does not show the observed response, provide a treatment-arm comparison, or quantify uncertainty. The record does not report the reason the trial was terminated. No conclusion about the relative response outcomes, or about the effects of either approach, can be drawn from the posted results.
In general, a clinical trial result applies most directly to the participants and conditions represented in its data and analysis. Interpreting a result also requires attention to uncertainty, study conduct, outcome measurement, and missing information. In this case, there is no primary outcome estimate or reported analysis to interpret, and enrollment is limited to the reported 1 participant. The randomized design does not create a treatment comparison when the outcome result is unavailable.
The registry record also does not establish whether the intended sample size was reached, how treatment was assigned, or whether secondary outcomes were analyzed. The listed status and dates are administrative details, not substitutes for outcome results. Thus, the record can be used to understand the planned comparison and the reason the primary result is withheld, but it cannot answer whether the response outcome differed between arms.
12. Why This Trial Matters Statistically
This trial raises a central statistical issue: a well-defined randomized question does not by itself yield an interpretable treatment comparison. The registry specifies two treatment strategies, a response definition, and a follow-up window, but reports enrollment of 1 and withholds the primary outcome for deidentification. Without an outcome estimate, readers cannot assess either the direction or precision of a comparison.
Randomization is useful because it is intended to limit systematic differences between treatment groups. In general, however, estimates from randomized trials still depend on having enough observed outcome information to describe the groups and quantify uncertainty. Very limited enrollment also means that a comparison, even if reported, would require careful attention to its precision and scope. The record does not provide a comparative estimate or an analysis population.
The case also illustrates the distinction between planning assumptions and observed evidence. Sample-size calculations can help plan a study under specified assumptions, but they are not evidence of an outcome and do not replace trial results. The registry describes general assumptions for planning illustrations, yet no numerical analysis result is reported. Readers should not interpret a planning illustration as an observed treatment effect or as proof that a trial had adequate information to resolve its question.
Finally, outcome privacy and statistical transparency can come into tension when very few participants are enrolled. The record explicitly withholds the primary result to protect deidentification. That choice leaves the clinical question unanswered in the posted results, while avoiding release of a participant-level result. The statistical importance is the clear separation between knowing what a trial intended to test and having enough reported evidence to evaluate the outcome.
13. 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 consequential limitation in interpreting this specific trial is that the primary tumor-response result is not shared. The registry states that the result is withheld to maintain the deidentification of the 1 participant accrued. Consequently, no response estimate, arm-specific result, or comparison is available in the posted record.
Enrollment is listed as 1, and the study status is terminated. The reason for termination is not reported in the registry record. The record does not identify the participant’s assigned arm, describe treatment received, or give the amount of follow-up available. The intended randomized, parallel-group design therefore cannot be evaluated as an implemented comparison from these results.
The registry reports no analyses. It does not give estimates or uncertainty for the primary endpoint or listed secondary outcomes, nor does it provide an analysis population, statistical model, missing-data approach, or multiplicity plan. The record also does not report the randomization ratio or the detailed procedures used for response assessment beyond the treating physician’s use of RECIST version 1.1.
These are limitations of the information in the registry record; they do not establish that particular procedures were or were not conducted outside the posted information. The record is sufficient to describe the planned comparison and endpoint, but not to assess treatment effects, precision, or the reasons the trial ended.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Immunotherapy With or Without Radiation Therapy for Metastatic Urothelial Cancer — NCT04936230.
- Registry record last updated 2025-08-17; status last verified 2025-08.
- Results first posted 2025-08-17.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
17. Record Summary
NCT04936230 is a randomized, open-label, parallel-group phase II trial of pembrolizumab with or without SBRT for platinum-ineligible or platinum-refractory metastatic urothelial cancer. The registry names the National Cancer Institute (NCI) as sponsor, reports enrollment of 1, and lists the status as terminated. The start date is 2022-11-22, and the primary completion date is 2024-08-15.
The primary outcome is tumor response, defined as complete or partial response by treating-physician assessment using RECIST version 1.1 up to 6 months from randomization. The registry withholds that result to maintain participant deidentification. No analyses are reported, and the reason for termination, analysis populations, and statistical analysis plan are not reported in the registry record.