Efficacy and Safety of Tislelizumab (BGB-A317) as Neo-Adjuvant Treatment in Participants With Colorectal Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Safety of Tislelizumab (BGB-A317) as Neo-Adjuvant Treatment in Participants With Colorectal Cancer (NCT05116085), a na phase 2 study. The primary outcome is Major Pathological Response (MPR) Rate.

2. Clinical Question

The study also listed pathological complete response, event-free survival, event-free survival at specified follow-up horizons, and adverse events among its secondary outcomes. Results for these outcomes are not reported in the registry record. Consequently, the record defines what the investigators intended to assess but does not establish the observed response frequency or the subsequent clinical course of participants.

3. Trial Design

This was a phase 2, single-group, multicenter, open-label study of tislelizumab as neoadjuvant treatment. It enrolled participants with early-stage (Stage II-III) colorectal cancer characterized as MSI-H or dMMR. The registry lists colorectal cancer as the condition and describes the study as addressing needs in people in China. Enrollment was 33. The study status is completed.

Participants received tislelizumab 200 milligrams by intravenous infusion once every 3 weeks for 3 treatment cycles before surgery. The registry states that tumor removal occurred within 10 weeks of the first dose. The primary outcome was major pathological response, assessed approximately 10 weeks after the first dose. It was defined by the amount of viable cancer remaining in the resected primary tumor after neoadjuvant therapy.

There was no randomized allocation, masking, or separate control arm. The study therefore describes outcomes among people treated within this study, not a randomized contrast between tislelizumab and another strategy. An open-label design means treatment assignment was not masked; the registry does not report further details about who assessed the tumor specimen or whether pathological assessment was blinded.

The registry lists pathological complete response, event-free survival, event-free survival at follow-up horizons, and adverse events as secondary outcomes. It does not report outcome estimates, confidence intervals, or analysis results for these endpoints. The registry also defines the efficacy analysis set as enrolled participants who received neoadjuvant treatment followed by surgery. The number meeting this definition is not reported in the registry record.

The study began on 2022-01-26, reached primary completion on 2023-09-26, and is recorded as completed. The registry record does not report a protocol-level explanation for the planned enrollment, the choice of assessment schedule, or additional operational details. Those details should not be inferred from the completed status or enrollment figure.

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.

Before assignment: This study consisted of a screening phase (and/or prescreening phase) and a treatment phase that included a neoadjuvant phase, surgery, and a disease follow-up phase.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The Efficacy Analysis Set included all enrolled participants who received neoadjuvant treatment followed by surgery.

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: The Safety Analysis Set included all enrolled participants who received ≥ 1 dose of study drug

6. Primary Endpoint

The registry lists the primary outcome as Major Pathological Response (MPR) Rate, measured over Approximately 10 weeks after first dose of study treatment.

The primary endpoint is the major pathological response rate. It measures the percentage of participants whose resected primary tumor has 10% or less remaining viable cancer cells after completing neoadjuvant therapy. The planned assessment was approximately 10 weeks after the first dose. The efficacy analysis set was defined as participants who were enrolled, received neoadjuvant treatment, and then underwent surgery.

A pathological response endpoint uses examination of the removed tumor to characterize the amount of viable cancer remaining after treatment. In general, such an endpoint can describe an early tissue response at the time of surgery. It differs from an outcome that follows participants for events over time: the endpoint is based on the surgical specimen, rather than on the later occurrence of an event. This is a general distinction between pathological response and time-to-event outcomes.

The registry record does not report the observed major pathological response percentage, the number of participants who met the response definition, or the confidence interval. The size of the defined efficacy analysis set is also not reported. Thus, the endpoint definition and intended population can be described, but the response frequency and its precision cannot be evaluated from the registry record.

The endpoint is not interchangeable with pathological complete response. The record lists pathological complete response separately as a secondary outcome, while major pathological response allows a specified amount of viable cancer to remain. Nor does a pathological response result alone establish longer-term event-free survival. These outcomes address different questions, and the registry record does not report their results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a response percentage represent?

For a binary outcome such as meeting or not meeting the major pathological response definition, the response rate is a proportion: the number of participants meeting the definition divided by the number included in the relevant analysis. The registry describes the endpoint as a percentage of participants and specifies the efficacy analysis set. The numerator and the size of that set are not reported in the registry record, so the proportion cannot be interpreted or recalculated from the available result information.

General statistical explanation: a percentage is a point estimate, meaning it is one estimate of the underlying response frequency in a population similar to the one studied. It does not convey precision by itself. A confidence interval describes a range of values compatible with the data and the chosen statistical method. A narrower interval generally indicates greater precision; a wider interval indicates more uncertainty. The registry specifies a 95% confidence interval for the primary outcome, but does not report its limits. The method used to construct it is not reported in the registry record.

Why does the analysis population matter?

The record defines the efficacy analysis set as all enrolled participants who received neoadjuvant treatment followed by surgery. This definition links the primary endpoint to treatment exposure and availability of a resected primary tumor for pathological assessment. The number meeting this definition is not reported. Overall enrollment of 33 is not a substitute for the analysis-set denominator, because the registry's definition requires treatment and subsequent surgery.

General statistical explanation: exclusions or missing endpoint assessments can affect both the denominator and the interpretation of an estimate. If participants without an assessment differ systematically from those assessed, the observed response proportion may not represent the broader enrolled group. A protocol can specify how missing outcomes are handled, but that approach is not reported in the registry record. It is therefore not possible to determine whether the primary analysis used an imputation method, a particular missing-data assumption, or another rule.

What can a single-group estimate establish?

This study has one treatment group and no randomized comparator. A response proportion in such a design is descriptive of the observed study group. It does not, by itself, quantify a treatment effect relative to an alternative. General statistical explanation: causal comparisons require a basis for distinguishing differences associated with treatment from differences in participant characteristics, selection, care, or measurement. Randomization is one way to support that distinction, but this study did not use randomized allocation. An external comparison would require additional assumptions and information that are not reported in the registry record.

The open-label design also means treatment was not masked. The registry does not report whether pathological assessments were conducted without knowledge of treatment or whether other safeguards were used to limit assessment bias. This is relevant because the primary endpoint depends on examination and classification of a tissue specimen. It should not be assumed that assessment was either blinded or unblinded beyond what the record states.

How should planning assumptions be read?

The registry's sample-size assumptions describe a planning illustration, not a reported trial result. The illustration is described as using a fraction of the observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The record also distinguishes planning outputs for time-to-event outcomes from those for other outcomes. The numerical planning outputs are not reported in the registry record.

General statistical explanation: sample-size planning asks what study size might be needed under stated assumptions about an effect, variability, significance threshold, and allocation. Changing the assumed effect or analysis method can change the planning result. A planning calculation does not indicate what the observed trial result was and does not measure the probability that a particular finding is true. It is not observed power. In this case, the actual study is single-group, whereas the stated planning illustration assumes equal allocation between two arms. That planning scenario should not be confused with the study's actual design.

The normal approximation is a general method that can be used to approximate a sampling distribution. Its suitability depends on the outcome and data characteristics. The registry record does not report the detailed calculation procedure, any justification of the approximation, or a protocol-specific sample-size rationale. Those details cannot be inferred from the assumptions alone.

Why can over-dispersion matter for count outcomes?

General statistical explanation: over-dispersion occurs when observed variability in count data is greater than a model assumes. If a model underestimates variability, standard errors can be too small and confidence intervals too narrow. This concept is relevant to some count outcomes, but the registry record does not describe an over-dispersion model or a count-based primary endpoint. The primary endpoint is a percentage of participants with a binary response definition. No claim about an over-dispersion adjustment should be made for this trial.

How do multiple outcomes affect interpretation?

The registry lists a primary endpoint and several secondary outcomes. General statistical explanation: when many outcomes or analyses are examined, the chance of at least one apparently unusual result can increase if each is considered separately. A prespecified hierarchy or multiplicity adjustment can address aspects of that issue. The registry record does not report a multiplicity procedure, an outcome hierarchy beyond identifying the primary endpoint, or analysis results. It is therefore not possible to determine how any multiplicity considerations were handled.

Finally, the record specifies a 95% confidence interval for the primary outcome, but does not report the interval or the statistical test used for any outcome. No p-value, adjusted estimate, subgroup analysis, or sensitivity analysis is reported in the registry record. Any interpretation that depends on such results would require information not present in the 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("Tislelizumab")
n      <- c(29)
events <- c(26)
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  Tislelizumab  29  26  89.7  72.6  97.8  73.6  96.4  73.5  96.2

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies major pathological response as the primary endpoint and lists pathological complete response, event-free survival, event-free survival at follow-up horizons, and adverse events as secondary outcomes. The record does not report results for these secondary outcomes or a multiplicity procedure. It is therefore not possible to assess how multiple outcome testing was handled or to distinguish confirmatory analyses from exploratory ones beyond the primary-versus-secondary labels in the record.

Missing-data handling is not reported in the registry record. The primary endpoint is based on a resected tumor, and the defined efficacy analysis set includes participants who received neoadjuvant treatment followed by surgery. The number in that analysis set, the number without an assessable specimen, and the handling of any missing pathology assessments are not reported. The overall enrollment of 33 does not establish the primary endpoint denominator.

The record defines the efficacy analysis population but does not report other analysis populations, exclusions, deviations, or sensitivity analyses. It is not possible to determine whether analyses were conducted under an intention-to-treat principle, how incomplete follow-up was treated, or whether missing event-free survival data were censored according to a particular rule. Those methods should not be inferred from the outcome names.

General statistical explanation: multiplicity concerns the interpretation of several statistical tests or estimates, while missing-data methods concern what is done when an outcome is unavailable. These are separate issues; a multiplicity approach does not resolve missing outcomes, and a missing-data method does not address the increased opportunity for chance findings across multiple analyses. The registry record does not report enough detail to evaluate either issue beyond the endpoint and population definitions.

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 3% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cardiac arrest (3.0%), myocarditis (3.0%), inflammation (3.0%), skin infection (3.0%).

The registry records serious adverse events for 4 of 33 participants at risk and other adverse events for 31 of 33 participants at risk in the tislelizumab group. One death is recorded. The listed serious adverse event terms are Cardiac arrest, Myocarditis, Inflammation, and Skin infection, each reported as 3.0%.

These are descriptive safety figures for the study group, not a comparison with another group. The record does not report whether each event was considered related to tislelizumab, the event grades, timing, duration, outcome, or whether participants could have experienced more than one event. The listed serious terms should not be interpreted as an exhaustive account of every adverse event or as proof of causation.

The death count is reported separately, but the registry record does not state whether the death was attributed to treatment, the cancer, another cause, or an adverse event. The figures also do not establish comparative safety, because the study had no separate control arm. General statistical explanation: safety proportions describe the frequency recorded under the study's definitions and observation period; interpretation depends on consistent event definitions, follow-up, attribution, and complete reporting. Those details are not reported in the registry record.

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

The registry record describes a completed single-group study of neoadjuvant tislelizumab in people with early-stage MSI-H or dMMR colorectal cancer. It specifies the treatment schedule, the surgical context, the primary pathological response definition, and selected adverse-event counts. Those details clarify what the study was designed to examine.

The record does not report the observed major pathological response rate or its 95% confidence interval. It also does not report results for the listed secondary outcomes. As a result, no conclusion about the observed frequency of major pathological response, its precision, or the event-free survival pattern can be drawn from this record. The analysis-set size and endpoint denominator are not reported either.

The design also limits what any study-group outcome could establish. Without a randomized comparator, the study cannot directly estimate how outcomes differed from an alternative treatment. A single-group response rate is not a comparative treatment effect. It also does not by itself establish that any observed event was caused by treatment.

The safety information shows reported serious adverse events for 4 of 33 participants at risk, other adverse events for 31 of 33 participants at risk, and 1 death. The serious terms listed each have a reported percentage of 3.0%. These figures are relevant descriptions of recorded events, but the registry does not state causality, event grades, timing, or the cause of death.

General statistical explanation: the strength of an inference depends on both the design and the completeness of the results. A clear endpoint definition helps explain what was intended to be measured, while an estimate and an uncertainty interval are needed to assess the observed result. A comparator is needed for a direct between-group contrast. In this case, the endpoint definition is available, but the primary estimate and comparator are not. The record therefore supports a careful description of study aims and recorded safety figures, not a conclusion about efficacy or comparative benefit.

14. Why This Trial Matters Statistically

Statistically, this study illustrates why an endpoint definition and an endpoint result are not the same thing. The registry gives a specific definition for major pathological response: the resected primary tumor must show 10% or less remaining viable cancer cells after neoadjuvant treatment. It also specifies a 95% confidence interval. Yet the observed percentage, interval limits, and efficacy analysis-set size are not reported in the registry record. The design can be described, but the primary outcome's magnitude and precision cannot be evaluated from the record.

The analysis population matters because the endpoint depends on surgery and assessment of the resected tumor. The record defines the efficacy analysis set around receipt of neoadjuvant treatment followed by surgery, rather than simply identifying all enrolled participants as the denominator. This distinction is essential when reading a percentage: the population included in the calculation determines what the estimate describes.

The single-group design is also statistically important. It can describe outcomes among participants receiving the study regimen, but it does not create a concurrent contrast that separates treatment-associated differences from other influences. This is a general distinction between estimating an outcome frequency in a group and estimating a comparative treatment effect.

The registry's safety entries likewise require careful framing. The reported counts and percentages describe events recorded in the treatment group, while information about attribution and event details is not reported. Reading these figures as causal evidence would go beyond the registry record. The study is therefore useful for understanding the questions and measurement approach, while the missing outcome estimates and absence of a comparator limit what can be concluded statistically.

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 primary outcome result is not reported in the registry record. The major pathological response estimate, its 95% confidence interval, and the size of the efficacy analysis set are all unavailable. This prevents evaluation of the outcome frequency and its statistical precision, despite the endpoint being defined.

The design has no randomized comparator. This means the study does not provide a direct estimate of the difference between tislelizumab and another treatment or control condition. The open-label design also means treatment was not masked. The registry does not state whether pathological assessment was blinded or report methods intended to reduce assessment bias.

Although overall enrollment was 33, the primary analysis population was defined as enrolled participants who received neoadjuvant treatment followed by surgery. The record does not report how many met that definition, whether any participants did not undergo surgery, how incomplete pathology information was handled, or whether there were exclusions from analysis. The primary endpoint denominator therefore cannot be established from enrollment alone.

Results for the listed secondary outcomes are not reported. The registry does not describe missing-data methods, censoring rules for event-free survival, a multiplicity procedure, subgroup or sensitivity analyses, or a protocol-specific sample-size justification. These gaps limit assessment of both the analysis strategy and the robustness of any findings.

Safety reporting is also incomplete for causal interpretation. Serious and other adverse-event counts are recorded, but the registry does not report event attribution, grades, timing, duration, overlap between participants or event categories, or the cause of the death. The listed serious terms and percentages should therefore be read as descriptive registry entries, not as a complete causal safety assessment.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Efficacy and Safety of Tislelizumab (BGB-A317) as Neo-Adjuvant Treatment in Participants With Colorectal Cancer — NCT05116085.
• Registry record last updated 2026-02-13; status last verified 2026-01.
• Results first posted 2026-02-13.
• 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

This completed phase 2 study was a single-group, multicenter, open-label investigation of neoadjuvant tislelizumab for early-stage (Stage II-III) MSI-H or dMMR colorectal cancer. Enrollment was 33. Participants received tislelizumab 200 milligrams intravenously once every 3 weeks for 3 cycles before surgery, which was planned within 10 weeks of the first dose.

The primary endpoint was major pathological response, defined by 10% or less remaining viable cancer cells in the resected primary tumor. The outcome was planned for assessment approximately 10 weeks after the first dose. The observed rate, confidence interval, and efficacy analysis-set size are not reported in the registry record.

The registry records serious adverse events for 4 of 33 participants at risk, other adverse events for 31 of 33 participants at risk, and 1 death. Listed serious terms each have a reported percentage of 3.0%. The record does not report event attribution or the cause of death. With no comparator and no reported primary outcome estimate, the record supports a description of the trial design and selected safety entries, but not a comparative efficacy conclusion.