Nivolumab in Treating Patients With Persistent, Recurrent, or Metastatic Cervical Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Nivolumab in Treating Patients With Persistent, Recurrent, or Metastatic Cervical Cancer (NCT02257528), a na phase 2 study. The primary outcome is Objective Tumor Response as Assessed by RECIST 1.1 Criteria.

2. Clinical Question

3. Trial Design

This is a phase II, single-group trial of nivolumab in patients with persistent, recurrent, or metastatic cervical cancer. The registry records enrollment of 26. Because there is no allocation to separate study arms and no control group, the design can describe outcomes among participants receiving nivolumab but cannot make a randomized comparison between treatments.

The intervention description states that participants receive nivolumab intravenously over approximately 60 minutes every 2 weeks. Treatment could continue for a maximum of 46 doses over 92 weeks, in the absence of disease progression or unacceptable toxicity. Laboratory biomarker analysis is also listed as an intervention. The registry does not describe a comparative biomarker treatment arm.

The study is unmasked, with masking listed as none. That means the record does not describe blinding of participants or study personnel. The registry identifies the National Cancer Institute as sponsor. The recorded study start is 2015-05-18, and primary completion is listed as 2019-03-05. The status is active, not recruiting; that status does not by itself establish that all analyses or results are available.

The primary outcome is objective tumor response assessed by RECIST 1.1 in eligible and evaluable participants. Progression-free survival and overall survival are listed as secondary outcomes. The registry lists 8 outcome measures, but the full details of every measure and its analysis are not reported in the registry record. The primary outcome timeframe is described as the average study treatment time was 3.8 months; a more precise response-assessment schedule is not reported in the registry record.

Sample-size justification, the basis for choosing the enrollment target, and a detailed statistical analysis plan are not reported in the registry record. Without a control group, the study’s primary proportion is an estimate of response within the study population, not an estimate of a treatment difference.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Eligible and evaluable participants

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 and evaluable patients

6. Primary Endpoint

The registry lists the primary outcome as Objective Tumor Response as Assessed by RECIST 1.1 Criteria, measured over The average of study treatment time was 3.8 months..

The primary endpoint is the percentage of eligible and evaluable participants with an objective tumor response. Response is defined as complete or partial tumor response assessed using RECIST 1.1. This endpoint expresses how often participants met the protocol’s specified tumor-response criteria in the population used for the primary analysis.

A response proportion is useful in a single-group study because it provides a direct summary of the observed frequency of the defined outcome. It is not, by itself, a measure of how much better the outcome is than it would have been under another treatment or without treatment. That comparative question requires an appropriate comparison group and a design that supports the comparison.

The registry specifies a 90% confidence interval for the primary percentage. A confidence interval communicates uncertainty around an estimate: a narrower interval indicates greater statistical precision, while a wider interval indicates less precision. The numerical percentage, the interval bounds, and the number of participants included in the primary analysis are not reported in the registry record. As a result, the response frequency and its precision cannot be assessed from the registry record.

The registry describes the primary population as eligible and evaluable participants. This may differ from everyone enrolled, depending on eligibility and evaluability rules, but those rules and the number analyzed are not reported in the registry record. The endpoint timeframe is given as the average study treatment time was 3.8 months. The record does not report a more detailed assessment schedule alongside the primary outcome.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a response percentage represent?

For a binary endpoint such as objective response, each participant is classified according to whether the defined event occurred. The response percentage summarizes the proportion classified as having a complete or partial response under RECIST 1.1. The denominator matters: it identifies the population from which that percentage is calculated. Here, the registry names eligible and evaluable participants as the primary population, but does not report the number analyzed or detailed rules for determining evaluability.

In general, an estimate based on fewer observations tends to be less precise than an estimate based on more observations. This is one reason the denominator should be read alongside a proportion. The recorded enrollment of 26 is not interchangeable with the primary analysis denominator: the registry does not state how many enrolled participants were eligible and evaluable for the primary endpoint. No response estimate is reported in the registry record, so the proportion and its precision cannot be reconstructed from the enrollment figure alone.

How should a confidence interval be understood?

A confidence interval gives a range of values compatible with the observed estimate under the statistical method used. In general, its width reflects statistical uncertainty: a narrower interval indicates more precision, and a wider interval indicates less. A 90% confidence interval is a procedure with a stated long-run coverage property under its assumptions; it is not a probability statement that a particular fixed parameter lies within the interval after the data have been observed.

The registry specifies a 90% confidence interval for the primary response percentage, but the estimate and interval bounds are not reported in the registry record. The method used to construct the interval is also not reported. Different interval procedures can behave differently, particularly when event counts or denominators are limited, so the method is relevant when evaluating an interval. No particular procedure should be assumed from the confidence level alone.

What does the single-group design allow?

A single-group design can estimate how often an outcome was recorded among participants meeting the analysis criteria. It does not estimate a randomized treatment contrast because there is no concurrent control group. In general, a treatment contrast depends on comparing outcomes under different assigned conditions while accounting for the design. A response percentage in one group cannot separate the effect of treatment from other influences, such as participant characteristics, the course of disease, other care, or the way participants were selected for the study.

The record lists allocation as not applicable and masking as none. These details describe the design; they do not supply a comparison that could support a causal estimate. Any interpretation should therefore stay with the descriptive question of what was observed among the analyzed participants, rather than treating the response proportion as proof of a treatment effect.

Why do outcome definitions and timing matter?

RECIST 1.1 provides the stated framework for classifying complete and partial tumor response. A prespecified definition helps make the outcome more consistent and interpretable, but the registry record does not include the actual assessment schedule, confirmation requirements, or detailed rules for handling assessments that cannot be evaluated. The primary timeframe is stated as the average study treatment time was 3.8 months. That description does not supply a participant-level follow-up distribution or establish when every response assessment took place.

Progression-free survival and overall survival are listed as secondary outcomes. These time-to-event outcomes require definitions of the event, the time origin, follow-up, and the handling of censoring. Those details and numerical results are not reported in the registry record. General methods for time-to-event outcomes account for the time participants are observed and for incomplete follow-up; no specific method can be attributed to this study from the available record.

What can be inferred from the safety counts?

Safety summaries commonly distinguish participants who experienced an event from the number of events, because one participant may experience more than one event. The registry gives counts of participants affected and participants at risk for the group-level adverse-event categories. It also lists selected serious adverse-event terms with percentages. The definitions, event-level counts, severity criteria, attribution rules, and detailed observation period are not reported in the registry record. The listed counts should therefore be read as registry summaries, not as a complete account of each participant’s event history.

The count of deaths is a safety outcome but does not, on its own, indicate the cause of death or whether a death was related to study treatment. In general, causal attribution requires clinical and temporal information, as well as a suitable comparison where the question is whether treatment changes risk. The registry entries do not provide those details.

What analysis details remain unknown?

The registry lists zero analyses. It does not report a detailed statistical analysis plan, a method for the primary confidence interval, an approach to missing outcome data, or procedures for multiple outcomes. It also does not report a sample-size justification. Those omissions prevent assessment of whether analytic choices were prespecified, how missing assessments affected the endpoint, or how the study’s precision was anticipated. The absence of these details should not be filled by assuming common practice; the specific procedures are not reported in the registry record.

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("Treatment (Nivolumab)")
n      <- c(25)
events <- c(1)
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  Treatment (Nivolumab)  25  1  4.0  0.1  20.4  0.7  19.5  0.9  19.6

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 8 outcome measures, with objective tumor response as the primary outcome and progression-free survival and overall survival among the secondary outcomes. When a study evaluates multiple outcomes, there can be more than one opportunity to observe an apparently notable result. Statistical approaches to multiplicity can address that issue, but the appropriate approach depends on the questions, outcome hierarchy, and analysis plan. Multiplicity procedures are not reported in the registry record, so it is not possible to determine whether or how the listed outcomes were handled together.

The primary analysis population is described as eligible and evaluable participants. The criteria for eligibility and evaluability, the number included in the primary analysis, and the handling of participants without an assessable response are not reported in the registry record. The record also does not state whether missing assessments were excluded, treated as nonresponse, or handled by another method. These choices can affect a response proportion, so the denominator and missing-data rules are needed for a complete interpretation.

The registry lists zero analyses and does not report a detailed statistical analysis plan. It therefore does not establish which analyses were prespecified, whether any interim analyses occurred, or how secondary outcomes were analyzed. Interim-analysis details are not reported in the registry record. A sample-size justification is also not reported in the registry record. Without these details, the reported enrollment alone cannot establish the intended precision or the basis for the study’s size.

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: abdominal pain (8.0%), tumor pain (8.0%), hypothyroidism (4.0%), colonic obstruction (4.0%), colitis (4.0%).

For the nivolumab group, the registry records 12 participants affected in the serious adverse-event category among 25 at risk. It records 24 participants affected in the other adverse-event category among 25 at risk, and 19 deaths. These are counts in the registry record; they should not be combined or treated as evidence that the intervention caused an event. The record does not report the cause of death or treatment attribution for these counts.

The listed serious adverse-event terms and percentages are abdominal pain, 8.0%; tumor pain, 8.0%; hypothyroidism, 4.0%; colonic obstruction, 4.0%; colitis, 4.0%; and bile duct stenosis, 4.0%. These are selected terms, not a complete description of all safety events. The registry record does not report event duration, timing, severity grading details, or the criteria used to attribute events to treatment. Percentages for the listed terms should be read as registry-reported values, not recalculated estimates.

In general, a participant count and an event count answer different questions: a participant can experience multiple events. The registry’s affected-participant summaries should not be interpreted as the total number of event occurrences. With no control group, these figures describe the recorded safety experience in the nivolumab group but cannot establish how it compares with another treatment or with background risk.

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

The trial is a phase II evaluation of nivolumab in persistent, recurrent, or metastatic cervical cancer. Its primary endpoint is the proportion of eligible and evaluable participants with complete or partial tumor response under RECIST 1.1. The registry specifies a 90% confidence interval for that proportion, but does not report the response estimate, the interval, or the primary analysis denominator. Consequently, the response frequency and its statistical precision cannot be judged from the registry record.

The single-group design means that any response proportion would describe outcomes among participants in the study. It would not show how outcomes would have differed under another treatment, because the registry does not describe a randomized control group. Even a clearly estimated proportion in a single group does not, by itself, isolate the effect of treatment from other factors that may influence outcomes.

The safety summaries provide counts of participants affected in adverse-event categories, selected serious adverse-event terms with percentages, and a death count. They do not establish causation. The registry record does not give detailed event timing, attribution, or a comparative safety estimate. The listed values therefore describe reported safety information, not a treatment-versus-control risk difference.

The record also lists progression-free survival and overall survival as secondary outcomes, but does not report numerical results or analysis details for them. The absence of those values in the registry record is not evidence of a particular outcome. Nor does a registry status of active, not recruiting, establish that every result is available or that all analyses are complete.

In short, the record identifies the clinical question and design, but the numerical primary result needed to answer the response question is not reported in the registry record. No conclusion about treatment efficacy or comparative safety can be drawn from the design and outcome definitions alone.

14. Why This Trial Matters Statistically

This trial raises a central statistical issue in clinical research: a clearly defined outcome is necessary, but the outcome’s numerical estimate and uncertainty are also needed to interpret the evidence. The registry defines objective response using RECIST 1.1 and specifies a 90% confidence interval. Without the observed percentage, interval bounds, and analysis denominator, readers cannot assess either the estimated response frequency or its precision.

The single-group design also illustrates the distinction between describing an outcome and estimating a treatment effect. A response proportion can summarize what happened in the study population. A treatment effect asks how outcomes compare under different treatment conditions. That comparative question requires a suitable comparator; it cannot be answered by a single-group proportion alone.

Analysis-population definitions matter as well. The registry names eligible and evaluable participants, while recording enrollment of 26. Since the number analyzed and the rules for eligibility and evaluability are not reported in the registry record, the relation between enrollment and the primary endpoint denominator is unclear. That information is essential for understanding the response estimate and its uncertainty.

The safety summaries offer another statistical distinction: participant counts, event counts, and causally attributed events are not interchangeable. The registry provides affected-participant counts, selected term percentages, and a death count, but does not report the detailed context needed to infer treatment attribution or comparative risk. These distinctions help prevent a descriptive registry summary from being overread as a causal conclusion.

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 important limitation for interpreting the primary endpoint is that the registry record does not report the objective-response percentage, its 90% confidence interval, or the number of eligible and evaluable participants analyzed. It therefore does not support an assessment of the endpoint’s magnitude or precision. Although enrollment is recorded as 26, that figure does not establish the primary analysis denominator.

The trial is single-group, with allocation listed as not applicable and masking listed as none. Without a control group, the study cannot provide a randomized treatment comparison. The registry record does not report details sufficient to assess potential effects of selection, outcome assessment, or other sources of bias. The absence of masking is relevant context, but the record does not describe how response assessments were conducted or reviewed.

Several analysis details are also unavailable. The registry does not report the statistical method used for the confidence interval, detailed eligibility and evaluability criteria, missing-data handling, a multiplicity approach, or a statistical analysis plan. It lists zero analyses. A sample-size justification is not reported in the registry record. The primary timeframe is described as the average study treatment time was 3.8 months, but a detailed assessment schedule is not reported.

Safety interpretation is limited by the lack of reported event timing, duration, attribution, and detailed severity criteria. The counts and selected serious adverse-event terms describe registry summaries, but do not establish causation or comparative safety. Numerical results and analysis details for the listed secondary outcomes are not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Nivolumab in Treating Patients With Persistent, Recurrent, or Metastatic Cervical Cancer — NCT02257528.
• Registry record last updated 2026-10-22; status last verified 2026-09.
• Results first posted 2020-08-12.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry describes a phase II, unmasked, single-group study of nivolumab for persistent, recurrent, or metastatic cervical cancer. Enrollment is recorded as 26. Nivolumab was administered intravenously over approximately 60 minutes every 2 weeks, for a maximum of 46 doses over 92 weeks in the absence of disease progression or unacceptable toxicity. The study is listed as active, not recruiting.

The primary outcome is the percentage of eligible and evaluable participants with complete or partial response under RECIST 1.1, with a specified 90% confidence interval. The numerical primary result, interval bounds, and analysis denominator are not reported in the registry record. Progression-free survival and overall survival are listed as secondary outcomes.

Safety summaries include 12 affected participants among 25 at risk in the serious adverse-event category, 24 affected among 25 at risk in the other adverse-event category, and 19 deaths. These counts do not establish treatment causation. A detailed statistical analysis plan, sample-size justification, and missing-data procedures are not reported in the registry record.