A Study of Duvelisib in Combination With Pembrolizumab in Head and Neck Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Duvelisib in Combination With Pembrolizumab in Head and Neck Cancer (NCT04193293), a na phase 1, phase 2 study. The primary outcome is Stage 1: Number of Participants With Dose-limiting Toxicities.

2. Clinical Question

The study was designed to assess the safety and preliminary efficacy of duvelisib in combination with pembrolizumab in participants with recurrent or metastatic head and neck squamous cell carcinoma. The registry record identifies dose-limiting toxicities as the primary Stage 1 outcome, assessed over 4 weeks or 28 days. It also lists response and longer-term outcomes, but reports no outcome data.

The listed secondary outcomes include Stage 1 overall response rate and, across Stage 1 and Stage 2, duration of response, progression-free survival, overall survival, pharmacokinetic measures, and treatment-emergent adverse events. These are intended areas of assessment, not findings: the registry record does not report their results.

3. Trial Design

This was a Phase 1b/2, single-group study sponsored by SecuraBio. The condition listed is head and neck squamous cell carcinoma. Allocation is recorded as not applicable, and masking as none. The registry record lists enrollment as 2 and states that only 2 participants received treatment.

The recorded study start was 2020-06-01, and the primary completion date was 2020-12-10. The study status is terminated. The registry description says termination was by the Sponsor; it does not report a reason for the termination beyond the stated concern about participant confidentiality when reporting data from only 2 treated participants.

The intervention group is named Duvelisib + Pembrolizumab. The Stage 1 description specifies duvelisib twice daily for 1 week, followed by duvelisib twice daily with pembrolizumab every 3 weeks. It describes Cycle 1 as 4 weeks, including the lead-in and a pembrolizumab dose with additional combination treatment, but the full regimen description is not reported in the registry record. No separate control arm is listed.

The primary outcome is the number of Stage 1 participants with dose-limiting toxicities, assessed over 4 weeks or 28 days. Secondary outcomes cover response, duration of response, progression-free and overall survival, pharmacokinetic measures, and treatment-emergent adverse events. The record lists 10 outcome measures, but no analysis entries are reported. As a result, the study design and intended assessments can be described, but the registry record does not support a treatment-effect estimate or a comparison between groups.

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: The study was terminated by the Sponsor due to low enrollment. Due to study termination and only 2 participants receiving treatment, there are concerns regarding participant confidentiality, therefore no data are being reported.

Overall Study

Analysis population for the primary outcome, as defined in the registry: This study was terminated by the Sponsor. Due to study termination and only 2 participants receiving treatment, there are concerns regarding participant confidentiality, therefore no data are being reported.

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: This study was terminated by the Sponsor. Due to study termination and only 2 participants receiving treatment, there are concerns regarding participant confidentiality, therefore no data are being reported.

6. Primary Endpoint

The registry lists the primary outcome as Stage 1: Number of Participants With Dose-limiting Toxicities, measured over 4 weeks or 28 days.

The primary endpoint is the number of participants with dose-limiting toxicities in Stage 1 during 4 weeks or 28 days. A dose-limiting toxicity is generally an adverse event meeting a protocol-defined threshold for severity, timing, or clinical significance during a specified assessment period. Such endpoints are used in early-phase research to characterize tolerability during initial treatment and, in some studies, to inform dose decisions. The specific definition and decision rules used in this study are not reported in the registry record.

The endpoint is a count of participants meeting the definition, rather than a direct measure of tumor response or survival. Interpreting such a count normally requires knowing how many participants were assessed, how the toxicity definition was applied, and how missing or incomplete observation was handled. The record states that 2 participants received treatment, but it does not report the endpoint data. It therefore does not establish how many participants experienced a dose-limiting toxicity.

Although the study summary also refers to preliminary efficacy, the primary endpoint is a safety measure. Response and other efficacy outcomes appear among the secondary outcomes, but their results are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record permits a description of the study structure and intended outcomes, but not of the statistical procedures used to analyze them. No analysis entries are reported, and the study’s statistical analysis plan is not reported in the registry record. The explanations below distinguish general statistical concepts from methods documented for this study.

What does a single-group design mean?

In a single-group study, participants receive the study intervention without a concurrent control group identified in the design. Outcomes can be described within the treated group, but there is no randomized comparison to estimate how outcomes differ from those under another treatment or usual care. Changes over time or observed events cannot, on their own, separate an intervention effect from other influences. This is a general design principle; the registry record identifies this study as single-group and lists no comparator.

Allocation is recorded as not applicable and masking as none. Those entries describe features of the registered design. They do not establish what procedures were used to assess outcomes, whether outcome assessors were blinded, or whether other safeguards were applied; such details are not reported in the registry record.

How is a dose-limiting toxicity endpoint interpreted?

Generally, a participant-count endpoint requires a protocol definition of what qualifies as a dose-limiting toxicity and a defined observation period. The registry record gives the Stage 1 period as 4 weeks or 28 days but does not give the toxicity criteria or rules for incomplete observation. A count alone is usually interpreted alongside the number of participants assessed and the way missing observations are handled. Although the record says that 2 participants received treatment, it does not report the endpoint count or the endpoint-specific analysis population.

For a binary outcome, an analysis might report the count and proportion meeting the definition, and might estimate uncertainty with a confidence interval. A confidence interval generally describes the range of values compatible with the data and the chosen statistical method; it is not a guarantee that the true value falls within that range. No count, proportion, or interval is reported for this endpoint, so none can be interpreted for this study.

What do the secondary outcomes imply?

The listed outcomes include response, duration of response, progression-free survival, overall survival, pharmacokinetic measures, and treatment-emergent adverse events. In general, time-to-event outcomes concern the time until a defined event, while accounting for participants whose event status is not observed by the end of follow-up. Their interpretation depends on definitions of the event, follow-up, censoring, and analysis population. Those details and results are not reported in the registry record. Pharmacokinetic outcomes such as maximum observed concentration and area under the curve describe aspects of drug exposure in general, but no study estimates or analysis methods for them are reported.

For count or binary outcomes, uncertainty can be substantial when observations are limited. General statistical methods may use confidence intervals to convey that uncertainty, but a method cannot compensate for the absence of reported outcome values. No effect estimates or uncertainty intervals are available in this record.

Are the sample-size assumptions the study’s analysis plan?

No. The record describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says that time-to-event illustrations use a total event count and other illustrations use participants per arm. These are stated assumptions for planning illustrations, not a reported design justification or analysis conducted in this single-group study. The record does not report the effect values or resulting sample-size figures, and it does not report a sample-size justification for the trial itself. The illustration cannot be read as observed power or as evidence about the study’s outcomes.

More generally, power calculations depend on assumptions about the effect to detect, variability or event rates, allocation, and statistical procedure. If assumptions do not match the eventual design or data, the resulting planning figures do not describe what the study observed. Here, no outcome results are reported, so there is no observed effect in the registry record to interpret or use for a recalculation.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists several outcomes across Stage 1 and Stage 2, including response, duration of response, progression-free survival, overall survival, pharmacokinetic measures, and treatment-emergent adverse events. When a study evaluates multiple outcomes or makes multiple statistical comparisons, the chance of a false-positive finding can increase if each is tested independently. General approaches to multiplicity include prespecifying a primary outcome, controlling error across tests, or treating secondary analyses as exploratory. The registry record does not report a multiplicity strategy or a statistical analysis plan.

The primary endpoint is identified as the number of Stage 1 participants with dose-limiting toxicities. However, the outcome values are not reported, and the record contains no analysis entries. It is not possible to determine whether secondary outcomes were analyzed, how any analyses were ordered, or whether results were adjusted for multiple testing.

Missing-data procedures and analysis populations are also not reported in the registry record. The record states that 2 participants received treatment and that data are not being reported because of confidentiality concerns. It does not describe endpoint-specific denominators, follow-up completeness, exclusions, or how incomplete observations would have been handled. For time-to-event outcomes, censoring rules and follow-up details are not reported. These omissions prevent assessment of how the planned outcomes would have been analyzed and limit any interpretation of the trial beyond its design and reporting status.

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

The record establishes that a Phase 1b/2, single-group study of duvelisib with pembrolizumab was conducted in recurrent or metastatic head and neck squamous cell carcinoma, was terminated, and had 2 participants receive treatment. It identifies dose-limiting toxicities during 4 weeks or 28 days as the primary Stage 1 endpoint and lists several secondary outcomes. Those are details about the study and its intended assessments.

The record does not establish how many participants experienced a dose-limiting toxicity, whether tumor responses occurred, or what the survival, pharmacokinetic, or adverse-event outcomes were. It therefore cannot establish the frequency of an outcome, the magnitude or precision of a treatment effect, or whether the combination performed differently from an alternative. No outcome data are being reported, and there is no control group listed for a direct comparison.

General statistical interpretation depends on estimates and their uncertainty, alongside the design and the completeness of the data. In this case, the absence of reported outcome values means that neither an estimate nor its uncertainty can be evaluated. The study’s termination does not itself indicate why treatment was stopped beyond the registry’s statement that termination was by the Sponsor, and the confidentiality explanation does not reveal what the unreported results were.

The conclusion should therefore remain narrow: the registry record describes a terminated study with 2 treated participants and does not report outcome data. It does not support a conclusion about benefit, lack of benefit, safety, or lack of safety.

12. Why This Trial Matters Statistically

This study illustrates why design details and result availability must be considered separately. The registry record identifies the phase, single-group structure, intervention, primary endpoint, and intended secondary outcomes. It also states that the study was terminated and that outcome data are not being reported. Knowing what investigators intended to measure does not reveal what the measurements showed.

It also highlights the importance of distinguishing a within-group description from a controlled treatment comparison. With no comparator group identified, the study does not supply a randomized estimate of the difference between the combination and another treatment. Even a reported outcome count would need to be interpreted in light of its definition, assessment population, observation period, and uncertainty; those outcome details are unavailable in this record.

Finally, the entry makes reporting limitations explicit. It gives a reason for not reporting data—confidentiality concerns in the context of 2 treated participants—but leaves the primary and secondary outcomes unreported. Statistical interpretation should respect that boundary rather than treating the absence of reported events as evidence of their absence. The record is informative about the study’s design and reporting status, but not about the results of treatment.

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 principal limitation is the absence of outcome data. The registry record explicitly says no data are being reported because the study was terminated and there are concerns about participant confidentiality. Consequently, the primary endpoint and listed secondary outcomes cannot be evaluated.

Participation was limited: the record lists enrollment of 2 and says 2 participants received treatment. With no outcome values, endpoint-specific denominators, or uncertainty estimates, the record cannot support a quantitative assessment of safety or efficacy. The single-group design also provides no comparator for a between-group treatment contrast.

Important methodological details are not reported in the registry record. These include the specific definition of dose-limiting toxicity, the statistical analysis plan, analysis populations, missing-data procedures, and details needed to interpret time-to-event outcomes. The treatment schedule description is incomplete, and further eligibility and participant-characteristic details are not reported. The listed sample-size assumptions are planning illustrations and do not constitute a reported design justification or analysis for this study.

These limitations are specific to the available record and do not establish what the unreported outcomes would have been. The appropriate interpretation is restricted to the registered design, study status, treatment count, and explicit statement that outcome data are not being reported.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: A Study of Duvelisib in Combination With Pembrolizumab in Head and Neck Cancer — NCT04193293.
• Registry record last updated 2023-09-21; status last verified 2023-09.
• Results first posted 2023-04-07.
• 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.

17. Record Summary

NCT04193293 is a Phase 1b/2, single-group study of duvelisib with pembrolizumab in recurrent or metastatic head and neck squamous cell carcinoma. The primary Stage 1 outcome is the number of participants with dose-limiting toxicities over 4 weeks or 28 days. Listed secondary outcomes include response, duration of response, progression-free survival, overall survival, pharmacokinetic measures, and treatment-emergent adverse events.

The record lists enrollment of 2, states that 2 participants received treatment, and gives the status as terminated. It says the Sponsor terminated the study and that outcome data are not being reported because of confidentiality concerns. No analysis entries are reported. Thus, the record describes the study’s intended assessments and status but does not provide results from which to evaluate its outcomes.