Bomedemstat and Maintenance Immunotherapy for Treatment of Newly Diagnosed Extensive Stage Small Cell Lung Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Bomedemstat and Maintenance Immunotherapy for Treatment of Newly Diagnosed Extensive Stage Small Cell Lung Cancer (NCT05191797), a na phase 1, phase 2 study. The primary outcome is Number of Participants Experiencing a Dose Limiting Toxicity (DLT).

2. Clinical Question

The study asked whether bomedemstat combined with maintenance immunotherapy could be evaluated in patients with newly diagnosed extensive-stage small cell lung cancer. Its primary endpoint was the number of participants experiencing a dose-limiting toxicity (DLT) within 21 days from initiation of treatment. This is a safety-focused question: it counts participants who meet the registry’s definition of a specified toxicity during the stated period.

The study also lists overall survival as a secondary outcome. The registry record does not report an overall-survival result. Consequently, the posted information describes the study question and treatment schedule more fully than it describes outcomes. The listed enrollment was 3, which is the number of participants recorded as enrolled, not a substitute for an endpoint result or a comparison of treatment effects.

3. Trial Design

This was a phase I/II interventional study with a single-group model. Masking was listed as none, and allocation was listed as not applicable. There was no parallel control arm in the design information, so the study was not structured to estimate a randomized treatment contrast. The registry lists University of Washington as sponsor.

The treatment group was described as receiving bomedemstat and atezolizumab. Bomedemstat was given by mouth once daily on days 1–21, and atezolizumab was given intravenously on day 1. Cycles were described as repeating every 21 days while there was no disease progression or unacceptable toxicity. The registry record does not provide further details about dose levels, dose changes, or treatment duration.

The listed enrollment was 3. The study started on 2022-04-11, had a primary completion date of 2023-08-03, and is recorded as terminated. The reason for termination is not reported in the registry record. The enrollment figure does not establish how many participants completed treatment, contributed data to every outcome, or were included in any particular analysis.

The title and official title describe newly diagnosed extensive-stage small cell lung cancer, while the condition list includes both extensive-stage and limited-stage small cell lung carcinoma. The registry record does not explain that difference or give eligibility details that would resolve it. It also does not report a detailed statistical analysis plan, a sample-size justification, or planned interim analyses. The study design information therefore supports a descriptive reading of the registered group and its posted counts, not a controlled efficacy comparison.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants Experiencing a Dose Limiting Toxicity (DLT), measured over Up to 21 days from initiation of treatment.

The primary endpoint is the number of participants experiencing a dose-limiting toxicity within 21 days from initiation of treatment. It is a participant count: each participant is classified according to whether at least one qualifying DLT occurred during the stated window. The registry describes qualifying toxicities as events assessed under CTCAE 5.03 and judged possibly, probably, or likely related to bomedemstat or atezolizumab.

The listed criteria include Grade 4 non-hematologic toxicity other than laboratory toxicity; Grade 3 non-hematologic toxicity lasting >3 days despite optimal supportive care; and specified Grade 3 or Grade 4 non-hematologic laboratory abnormalities when medical intervention is required or the abnormality leads to hospitalization. The description also includes thrombocytopenia with clinically significant sequelae, febrile neutropenia, and Grade 5 toxicity.

In general, a DLT endpoint is used in early-stage drug research to summarize important toxicities over a defined period. Its interpretation depends on the event definition, the relationship assessment, the observation window, and how completely participants are followed during that window. Here, the registry record gives the definition and timeframe, but does not report the number of participants who met the DLT definition. The safety counts elsewhere in the record should not be treated as the DLT result: the listed adverse-event categories are not identified as DLTs, and their observation period is not reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a single-group phase I/II study and identifies a participant count as the primary endpoint. These design and measurement details determine what can be summarized statistically. They do not, on their own, supply a result. The registry record lists 3 enrolled participants, but does not report an analysis of the primary endpoint or the secondary overall-survival outcome.

What does a participant count represent?

For this endpoint, the recorded outcome is whether a participant experienced a qualifying DLT during the specified window. A count of participants with the event is different from a count of individual toxicity episodes: the endpoint title is explicitly framed as the number of participants experiencing a DLT. The event definition also includes a judgement about whether a toxicity was possibly, probably, or likely related to either study drug. The registry record does not report how many participants met this definition.

In general, counts should be read alongside their denominators and the rules defining who was observed. The adverse-event summary lists 3 participants at risk in each of its two categories. Those denominators describe the posted safety summary, not necessarily the analysis population for the primary endpoint. The record does not explain whether all enrolled participants had complete observation through the DLT window or how any incomplete follow-up was handled.

Why does the observation window matter?

A DLT count is tied to the stated period: up to 21 days from initiation of treatment. An event outside that period would not automatically meet this endpoint’s timing criterion, although it could still be relevant to other safety summaries. A fixed window makes the endpoint more specifically defined, but interpretation still depends on adequate observation during that window. The registry gives the window and criteria but does not provide participant-level timing or completeness of follow-up.

The DLT definition is not simply a list of every adverse event. It specifies severity, type, duration for one criterion, circumstances for some laboratory abnormalities, and a relationship assessment. For example, the recorded definition includes Grade 4 non-hematologic toxicity other than laboratory toxicity, Grade 3 non-hematologic toxicity lasting >3 days despite optimal supportive care, and certain Grade 3 or Grade 4 non-hematologic laboratory abnormalities under stated conditions. It also includes thrombocytopenia with clinically significant sequelae, febrile neutropenia, and Grade 5 toxicity. As a result, the general adverse-event counts cannot be substituted for a DLT count.

What can a single-group design estimate?

In general, a single-group study can describe the experience recorded among participants who received the study treatment. Without a comparator group, it cannot directly estimate a randomized difference between treatment strategies. Changes over time or observed events cannot be attributed to the intervention solely from the design. The registry lists allocation as not applicable, masking as none, and a single-group model; it does not provide a like-for-like control comparison.

This is especially important when interpreting a small enrolled group. A count can be exact for the participants represented in the record while still being imprecise as an estimate of what might be seen in a wider population. In general, uncertainty intervals communicate the range of values compatible with data under a specified statistical method. No confidence interval for the primary endpoint is reported in the registry record, and none can be inferred from the safety summary alone.

What statistical analyses are reported?

The record lists 4 outcome measures and 0 analyses. It names overall survival as a secondary outcome, but does not report its analysis, follow-up details, or result. The statistical test or model for any outcome, handling of censoring, covariate adjustment, and analysis population are not reported in the registry record. The analysis plan and any interim analyses are also not reported. It would therefore be inappropriate to describe a particular inferential method as the study’s method.

The calculated tables and plots can organize the record’s available information, but they do not replace missing trial analyses. Any recalculated value, when explicitly labelled as recalculated, is a simple unadjusted calculation from posted summary statistics; it is not the sponsor’s analysis. Where a discrepancy is identified, the sponsor’s own analysis takes precedence. No sponsor analysis is reported for the primary or secondary outcome.

Sample-size illustrations are planning exercises, not results from the trial. The stated assumptions describe two-sided significance level 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. Such illustrations do not describe the single-group study’s actual design or establish observed power. The registry record does not report the study’s own sample-size justification. The illustration assumptions should therefore not be mistaken for protocol details or evidence that the trial was powered to answer its registered question.

Overall, the statistical methods that can be described from the record are the endpoint’s count-based form, its event definition and timeframe, and the single-group structure. The methods needed to assess precision or make an outcome comparison 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 (Bomedemstat, Atezolizumab)")
n      <- c(3)
events <- c(0)
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 (Bomedemstat, Atezolizumab)  3  0  0.0  0.0  70.8  0.0  56.1  0.6  60.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary safety endpoint, the number of participants experiencing a DLT, and identifies overall survival as a secondary outcome. It also states that there are 4 outcome measures, but the available record does not give a complete account of their definitions or results. The record lists 0 analyses. No multiplicity strategy, testing hierarchy, or adjustment for examining multiple outcomes is reported in the registry record.

In general, when a study evaluates several outcomes, the chance of at least one apparently unusual result can depend on how many questions are tested and how the analysis is planned. A prespecified hierarchy or other multiplicity approach can clarify which findings are confirmatory and which are exploratory. Since the analysis plan and any such approach are not reported, the posted record does not support a claim about how multiple outcomes were handled.

Missing-data methods and analysis populations are also not reported in the registry record. The enrollment count of 3 does not establish that every participant contributed complete data to every endpoint. The record does not say whether participants with incomplete follow-up were excluded, counted in a particular way, or handled using another method. For overall survival, details about follow-up, censoring, and the analysis population are not reported.

These omissions matter because estimates and uncertainty depend on who was included and how missing observations were treated. They do not show that data were missing or that a particular method was used; they mean the registry record does not describe those matters.

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 non-serious adverse event terms

The posted safety summary lists 3 participants at risk for serious adverse events and 0 affected. In a separate category, it lists 3 participants at risk for other adverse events and 3 affected. The summary also lists 3 deaths. These figures refer to different categories and should not be combined or treated as interchangeable.

The record does not provide event-level descriptions for the serious adverse-event category, and its list of top serious terms is empty. It also does not state the timing, causes, or treatment attribution of the deaths. The DLT definition has its own severity, timing, and relatedness criteria; the general adverse-event counts do not tell us how many participants met that definition. The DLT result itself is not reported in the registry record.

In general, a count is most informative when its denominator, event definition, observation period, and handling of follow-up are clear. The at-risk counts are shown, but the adverse-event observation period and participant-level details are not reported in the registry record. These safety figures describe what is posted for this group; they do not establish a causal relationship between treatment and an event, nor do they provide a comparison with another group.

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

The result that can be described is the structure and scale of the registered study: a phase I/II, single-group study of bomedemstat with atezolizumab, with 3 participants enrolled and a primary endpoint defined as a DLT count within 21 days. The record is marked terminated. It also posts safety summary counts: 0 of 3 participants affected in the serious adverse-event category, 3 of 3 affected in the other adverse-event category, and 3 deaths. The record does not report the primary endpoint result or an outcome analysis.

These figures do not show whether the combination was effective or ineffective. The record provides no reported primary endpoint analysis, no overall-survival analysis, and no comparator group. A single-group experience cannot establish how outcomes would differ under another treatment strategy. The listed deaths cannot be attributed to treatment from the information recorded, because cause and relationship are not reported.

In general, observed counts in a small study are descriptions of the people represented, not guarantees about what would be seen in another group of patients. Precision depends on the amount and quality of data, as well as the analysis. Here, the primary result and its uncertainty are not reported in the registry record. The available adverse-event counts should not be treated as an estimate of DLT frequency because the event definitions differ.

The record also does not explain why the study was terminated or whether all planned outcomes were collected. That absence does not tell us the reason or the completeness of the data. It limits what can be concluded from the posted information. Thus, the study’s record is informative about its intended question, design, treatment schedule, enrollment, status, and selected safety counts, but it does not provide the outcome evidence needed to answer its primary question.

14. Why This Trial Matters Statistically

This study matters statistically because it illustrates the distinction between a registered research question and a reported result. The registry specifies a clinically focused safety endpoint, including a defined observation window and criteria for qualifying toxicities. Yet the primary endpoint count is not reported. Without that count, the central registered safety question cannot be answered from the posted record.

The single-group design also makes the scope of interpretation especially important. Descriptive counts can summarize what was recorded among participants receiving the combination, but a control group is absent. The study therefore does not offer a randomized comparison. That distinction is not a technical footnote: it determines which questions the design can address and which comparisons it cannot support.

The record also shows why safety summaries need careful reading. Serious adverse events, other adverse events, deaths, and DLTs are not interchangeable categories. The summary counts do not include enough detail to establish event timing, cause, or treatment attribution, and they do not supply the primary DLT outcome. Keeping the categories separate avoids turning a sparse summary into a stronger claim than it supports.

Finally, the record lists 3 enrolled participants and a terminated status, but does not report the reason for termination or outcome analyses. Those details shape the limits of interpretation. The statistical lesson is to separate what is explicitly recorded from what would require an analysis or information not available in the registry record. That discipline is useful when reading early-stage studies and any registry entry with limited posted results.

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 main trial-specific limitation is the small listed enrollment: 3 participants. This limits the amount of information available for describing safety outcomes and makes any count highly dependent on the experience of each participant. The registry record does not provide a reported primary endpoint estimate or an uncertainty interval.

The study is single-group, with allocation listed as not applicable and masking listed as none. There is no comparator arm for a like-for-like assessment. Consequently, the posted information cannot establish a comparative treatment effect. The registry also records the study as terminated, but the reason for termination is not reported in the registry record.

There are important gaps in outcome reporting. The primary DLT endpoint is defined, but its result is not reported. Overall survival is listed as a secondary outcome, but no analysis or result is reported. Although 4 outcome measures are listed, 0 analyses are recorded. The adverse-event summary lacks event-level descriptions and does not report the observation period, death causes, or treatment attribution.

The registry record does not report eligibility details, the sample-size justification, the statistical analysis plan, interim analyses, missing-data methods, or analysis populations. It also does not explain why the condition list includes both extensive-stage and limited-stage small cell lung carcinoma when the titles identify newly diagnosed extensive-stage disease. These missing details leave uncertainty about the study population and how outcomes would have been analyzed. They should be treated as limits of the available record, not as evidence that a particular procedure was or was not used.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Bomedemstat and Maintenance Immunotherapy for Treatment of Newly Diagnosed Extensive Stage Small Cell Lung Cancer — NCT05191797.
• Registry record last updated 2024-09-26; status last verified 2024-09.
• Results first posted 2024-09-26.
• 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 record describes a phase I/II, single-group study of bomedemstat with atezolizumab for patients with newly diagnosed extensive-stage small cell lung cancer. Treatment was described as bomedemstat by mouth once daily on days 1–21 and atezolizumab intravenously on day 1, with cycles repeating every 21 days in the absence of disease progression or unacceptable toxicity.

The listed enrollment was 3. The study started on 2022-04-11, had a primary completion date of 2023-08-03, and is recorded as terminated. The primary endpoint was the number of participants experiencing a DLT within 21 days from treatment initiation. Overall survival was listed as a secondary outcome.

The record reports no outcome analyses. It lists 0 of 3 participants affected in the serious adverse-event category, 3 of 3 affected in the other adverse-event category, and 3 deaths. It does not report the DLT result, overall-survival analysis, reason for termination, or further details needed to interpret the deaths.