This page separates reported registry information from statistical interpretation. The ClinicalTrials.gov record identifies six registered primary endpoints and indicate that results are posted, but contain no formal statistical analyses. Numerical treatment-effect estimates, confidence intervals, and p-values are therefore not presented here unless they are explicitly contained in the ClinicalTrials.gov record.
1. Trial at a Glance
ZUMA-1 was a non-randomized, sequential phase 1/2 treatment study evaluating axicabtagene ciloleucel in adult participants with refractory or relapsed aggressive non-Hodgkin lymphoma. The registry lists 307 participants enrolled, seven arms, no masking, and treatment as the primary purpose.
| Feature | ZUMA-1 |
|---|---|
| Trial name | ZUMA-1 |
| ClinicalTrials.gov identifier | NCT02348216 |
| Therapeutic area | Hematology |
| Phase | Phase 1/2 |
| Status | COMPLETED |
| Allocation | NON_RANDOMIZED |
| Design model | SEQUENTIAL |
| Masking | NONE |
| Primary purpose | TREATMENT |
| Enrollment | 307.0 |
| Arms | 7 |
| Lead sponsor | Kite, A Gilead Company |
| Sponsor type | INDUSTRY |
2. Clinical Question
The registry describes ZUMA-1 as a study evaluating the safety and efficacy of KTE-C19, now represented in the registry intervention list as axicabtagene ciloleucel, in adult participants with refractory or relapsed aggressive non-Hodgkin lymphoma. The statistical structure is different from a conventional randomized comparative trial because allocation is explicitly recorded as non-randomized and the design model as sequential.
Population
Adult participants with refractory diffuse large B cell lymphoma, relapsed diffuse large B-cell lymphoma, transformed follicular lymphoma, primary mediastinal B-cell lymphoma, or high grade B-cell lymphoma.
Intervention
Axicabtagene ciloleucel, with the registry also listing fludarabine, cyclophosphamide, levetiracetam, tocilizumab, dexamethasone, high-dose methylprednisolone, bendamustine, rituximab, doxorubicin, prednisone, vincristine, and ifosfamide among the interventions.
Comparator
No randomized comparator is identified in the ClinicalTrials.gov record. Allocation is recorded as NON_RANDOMIZED.
Primary question
How safe and effective is axicabtagene ciloleucel in the study populations represented by the sequential phase 1/2 program?
3. Trial Design
Phase 1 study
- Axicabtagene ciloleucel is the identified study intervention.
- The registered primary endpoint concerns adverse events defined as dose-limiting toxicities.
- The registry time frame begins at the first infusion date of axicabtagene ciloleucel.
Pivotal and safety-management cohorts
- The registry identifies a pivotal study with Cohorts 1 and 2.
- The safety-management study includes Cohorts 3, 4, 5, and 6.
- Primary endpoints differ between the pivotal and safety-management components.
The registry lists seven arms overall, but the registry-reported trial extraction does not provide a complete arm-by-arm treatment description or allocation count for all seven arms. The analysis therefore avoids assigning participants to treatment groups that are not explicitly identified in the ClinicalTrials.gov record.
4. Trial Timeline and Follow-Up
Trial start
The registry lists April 21, 2015 as the study start date.
Primary completion
The registry lists July 27, 2023 as the primary completion date.
Current registry status
the ClinicalTrials.gov record in the ClinicalTrials.gov record lists the study status as COMPLETED.
5. Registered Primary Endpoints
ZUMA-1 has six registered primary endpoints in the ClinicalTrials.gov record. All six are classified as binary endpoints in the extraction. The endpoints are distributed across the phase 1 study, the phase 2 pivotal study, and four safety-management cohorts.
| Study component | Registered primary endpoint | Time frame |
|---|---|---|
| Phase 1 Study | Number of Participants Experiencing Adverse Events (AEs) Defined as Dose Limiting Toxicities (DLTs) | First infusion date of axicabtagene ciloleucel up to 30 days |
| Phase 2 Pivotal Study (Cohorts 1 and 2) | Overall Response Rate (ORR) as Assessed by Investigator Per Revised International Working Group (IWG) Response Criteria for Malignant Lymphoma | First infusion date of axicabtagene ciloleucel up to last follow-up visit; maximum duration: 7.7 years |
| Phase 2 Safety Management Study (Cohort 3) | Percentage of Participants With Treatment-Emergent Cytokine Release Syndrome (CRS) and Neurologic Toxicities by Severity Grades | First infusion date of axicabtagene ciloleucel up to last follow-up visit; maximum duration: 6.8 years |
| Phase 2 Safety Management Study (Cohort 4) | Percentage of Participants With Treatment-Emergent CRS and Neurologic Toxicities by Severity Grades | First infusion date of axicabtagene ciloleucel up to last follow-up visit; maximum duration: 5.4 years |
| Phase 2 Safety Management Study (Cohort 5) | Percentage of Participants With Treatment-Emergent CRS and Neurologic Toxicities by Severity Grades | First infusion date of axicabtagene ciloleucel up to last follow-up visit; maximum duration: 4.4 years |
| Phase 2 Safety Management Study (Cohort 6) | Percentage of Participants With Treatment-Emergent CRS and Neurologic Toxicities by Severity Grades | First infusion date of axicabtagene ciloleucel up to last follow-up visit; maximum duration: 4.1 years |
Endpoint definitions
The phase 1 DLT endpoint is defined using axicabtagene ciloleucel-related events with onset within the first 30 days following infusion. The registry definition includes grade 4 neutropenia lasting > 21 days, grade 4 thrombocytopenia lasting > 35 days from day of cell transfer, any axicabtagene ciloleucel-related adverse event requiring intubation, and other specified grade 3 or grade 4 toxicities.
For the phase 2 pivotal component, ORR is defined as the percentage of participants achieving either a complete response or partial response, assessed by study investigators using revised IWG Response Criteria for Malignant Lymphoma. The registry-reported definition describes complete response as complete disappearance of all detectable clinical evidence of disease and disease-related symptoms, with required regression of lymph nodes and nodal masses.
For the safety-management cohorts, treatment-emergent adverse events are defined as adverse events with onset on or after the start of treatment. CRS is graded using the Lee et al 2014 framework. The registry definition distinguishes grades 1 through 4 according to increasing intervention requirements and severity, with grade 4 described as life-threatening symptoms and requirements for ventilator support.
6. Results Status
the ClinicalTrials.gov record states that results are posted and that 28 outcome measures are posted. However, the registry-reported extraction contains no formal statistical analyses. That distinction is important: an outcome can have posted registry data without the registry extraction supplying a formal between-group hypothesis test, effect estimate, confidence interval, or p-value.
Because the design is non-randomized and the registry-reported statistical-analysis field is empty, conventional comparative quantities such as a randomized-treatment hazard ratio or randomized-group risk ratio cannot be presented as if they were documented analyses of this registry record.
7. Planned Analysis
The registry identifies six binary primary endpoints. For binary outcomes, the central statistical task is to estimate the proportion of participants experiencing the prespecified event and to quantify uncertainty around that proportion. In a non-randomized sequential study, those estimates are primarily descriptive unless the protocol specifies a formal benchmark, historical control, or other comparison.
Phase 1 dose-limiting toxicities
The phase 1 primary endpoint is the number of participants experiencing adverse events defined as DLTs during the first 30 days after the first axicabtagene ciloleucel infusion. A typical analysis would summarize the number and percentage of participants meeting the DLT definition, with an exact or otherwise appropriate binomial confidence interval when inferential precision is desired.
where x is the number of participants meeting the endpoint definition and n is the relevant analysis population. The registry extraction in the ClinicalTrials.gov record does not provide the corresponding formal statistical-analysis estimate.
Overall response rate
ORR is a binary response endpoint because each participant is classified according to whether a complete response or partial response was achieved under the registered response criteria. The natural descriptive estimand is therefore a response proportion. If a formal comparison were specified, the analysis would depend on the design and prespecified comparator; because allocation is non-randomized and no formal statistical analysis is reported here, a randomized treatment-effect interpretation would not be appropriate.
CRS and neurologic toxicities
The four safety-management primary endpoints concern the percentage of participants with treatment-emergent CRS and neurologic toxicities by severity grade. The statistical description should preserve the ordinal severity information rather than collapsing all grades into a single binary outcome when the purpose is to understand the safety profile. Grade-specific counts and percentages can show how the distribution of toxicity changes across severity categories.
What can be estimated
For each binary endpoint, the observed event proportion can be calculated from the appropriate analysis population. Confidence intervals can quantify sampling uncertainty around those proportions.
What cannot be assumed
A non-randomized cohort proportion is not automatically a causal treatment effect. Without a randomized comparator or prespecified external benchmark, differences across cohorts can reflect differences in study populations or procedures.
8. Statistical Methodology
Binary endpoint analysis
Each registered primary endpoint is classified as binary in the ClinicalTrials.gov record. A binary endpoint records whether an individual participant meets a predefined condition, such as experiencing a DLT or achieving an overall response. The basic estimand is the event probability within the defined analysis population.
The observed proportion is straightforward, but its interpretation depends critically on the denominator. In a sequential study with different cohorts and different follow-up windows, the denominator and analysis population must be stated explicitly.
Confidence intervals for proportions
For a binary endpoint, a confidence interval around the observed proportion communicates statistical precision. Exact binomial intervals are one common approach, particularly when event counts are small. The registry extraction does not identify a particular confidence-interval method, so no specific interval procedure is attributed to the ZUMA-1 protocol on this page.
Response-rate analysis
ORR combines complete response and partial response into a single binary efficacy endpoint. Statistically, that simplifies the endpoint to responder versus non-responder, but the clinical meaning still depends on the underlying response criteria. The registry specifically identifies investigator assessment according to revised IWG Response Criteria for Malignant Lymphoma.
Safety-event analysis
Safety endpoints require careful attention to exposure and observation time. A treatment-emergent event is defined in the registry as an adverse event with onset on or after the start of treatment. CRS and neurologic toxicities are further characterized by severity grade. A useful safety analysis therefore reports both how often events occur and how severe they are.
Non-randomized interpretation
Randomization creates a design-based mechanism for balancing measured and unmeasured prognostic factors in expectation. ZUMA-1 is explicitly classified as non-randomized. Consequently, an observed difference between sequential cohorts cannot automatically be interpreted as the causal effect of axicabtagene ciloleucel in the same way as a difference generated by randomized treatment assignment.
Sequential design
A sequential design can allow information from earlier stages or cohorts to inform subsequent study development or safety management. Statistically, however, sequential observation creates additional opportunities for selection, changing eligibility, changing management procedures, and evolving event ascertainment. Those features need to be understood before combining cohort-level estimates into a single summary.
9. Statistical Methods Explained
Why is ORR a binary endpoint?
ORR classifies each participant as having achieved either a complete response or a partial response, versus not achieving either response category. This creates a proportion that is easy to summarize, but it discards the additional information contained in the distinction between complete and partial response and in the timing and duration of response.
Why does the non-randomized design matter?
In a randomized trial, treatment groups are created by the randomization mechanism. Here, the registry explicitly records allocation as non-randomized. Therefore, if two cohorts have different response proportions, the difference can have several explanations besides treatment itself, including differences in participant characteristics, disease status, enrollment period, or clinical management.
Why are confidence intervals important for a response rate?
An observed response percentage is an estimate of an underlying event probability. A confidence interval communicates how precisely that probability has been estimated under the selected statistical model. A wider interval indicates greater uncertainty; a narrow interval indicates greater statistical precision. Neither interval describes the response probability of every individual participant.
Why should CRS be reported by severity grade?
Severity contains information that a simple yes/no indicator loses. Two cohorts could have the same overall incidence of CRS while having very different distributions of grade 1, grade 2, grade 3, and grade 4 events. The registered endpoint therefore appropriately specifies toxicity by severity grades.
Why must the analysis denominator be explicit?
A percentage has meaning only relative to its denominator. ZUMA-1 contains multiple study components and cohorts, while the primary endpoints use different populations and follow-up definitions. Combining denominators across cohorts without a prespecified rationale could produce a number that does not correspond to any registered endpoint.
Can a posted registry result be treated as a formal hypothesis test?
No. Posting an outcome measure and supplying a formal statistical comparison are different things. The ClinicalTrials.gov record say that results are posted, but no formal statistical analyses were posted. Consequently, this page does not infer a p-value, confidence interval, or comparative effect estimate from the mere existence of posted outcome data.
10. Safety Results
| Study component / cohort | Participants with serious adverse events / at risk |
|---|---|
| Phase 1 Study: Axicabtagene Ciloleucel | 5/7 |
| Phase 2 (Pivotal Study): Cohort 1 | 40/77 |
| Phase 2 (Pivotal Study): Cohort 2 | 14/24 |
| Phase 2 (Safety Management Study): Cohort 3 | 26/38 |
| Phase 2 (Safety Management Study): Cohort 4 | 24/41 |
| Phase 2 (Safety Management Study): Cohort 5 | 27/50 |
The safety results illustrate why adverse-event interpretation should remain tied to the study component and denominator. The value 40/77, for example, describes affected participants relative to the registry-reported at-risk count for that specific pivotal cohort; it does not establish a causal difference from the 14/24 value in another cohort.
11. Clinical Biostats Interpretation of the Available Safety Data
A serious-adverse-event value such as 5/7 means that the registry field identifies 5 affected participants among 7 participants at risk in that study component. It is a descriptive frequency, not a hazard ratio or a randomized treatment effect.
The phase 1 study and phase 2 cohorts are components of a sequential, non-randomized program. Comparing their percentages as though they were parallel randomized treatment groups could confound treatment effects with differences in cohort composition, study stage, eligibility, follow-up, and safety-management procedures.
The number of affected participants does not by itself establish severity, duration, causality, or whether an event was related to axicabtagene ciloleucel. Those questions require the corresponding adverse-event definitions and detailed safety tables.
Safety proportions are conditional on the population at risk. A value calculated using a different denominator can answer a different question. This is particularly important when multiple cohorts have different sample sizes and different registered follow-up windows.
12. Primary Endpoint Interpretation
The primary endpoints address three distinct statistical questions within the ZUMA-1 program: early treatment-related toxicity in phase 1, tumor response in the pivotal phase 2 study, and treatment-emergent CRS and neurologic toxicity in the safety-management cohorts.
| Endpoint family | Statistical quantity | Interpretive question |
|---|---|---|
| DLT | Proportion with a registered DLT | How frequently did participants meet the prespecified dose-limiting-toxicity definition during the first 30 days? |
| ORR | Proportion achieving CR or PR | How frequently did participants achieve a response under the registered response criteria? |
| CRS | Percentage by severity grade | How frequently did treatment-emergent CRS occur, and how was severity distributed? |
| Neurologic toxicities | Percentage by severity grade | How frequently did treatment-emergent neurologic toxicities occur, and how was severity distributed? |
These endpoints should not be treated as interchangeable measures of a single underlying quantity. DLT is a prespecified early safety construct, ORR is an efficacy construct, and CRS and neurologic toxicity are treatment-emergent safety constructs. Each has its own analysis population and time frame.
13. Time Frames and Estimands
The registered time frames are statistically important because the same event definition can produce different estimates when observation windows differ. ZUMA-1 uses a 30-day window for the phase 1 DLT endpoint, while the phase 2 ORR and safety-management endpoints extend from first infusion to the last follow-up visit, with maximum durations ranging from 4.1 to 7.7 years depending on the endpoint.
| Endpoint | Registered observation window | Primary statistical implication |
|---|---|---|
| Phase 1 DLT | First infusion through 30 days | Early toxicity probability within a fixed short-term window |
| Phase 2 pivotal ORR | First infusion through last follow-up; maximum 7.7 years | Response proportion accumulated over the registered follow-up period |
| Safety-management Cohort 3 | First infusion through last follow-up; maximum 6.8 years | Longitudinal ascertainment of treatment-emergent CRS and neurologic toxicity |
| Safety-management Cohort 4 | First infusion through last follow-up; maximum 5.4 years | Longitudinal ascertainment of treatment-emergent CRS and neurologic toxicity |
| Safety-management Cohort 5 | First infusion through last follow-up; maximum 4.4 years | Longitudinal ascertainment of treatment-emergent CRS and neurologic toxicity |
| Safety-management Cohort 6 | First infusion through last follow-up; maximum 4.1 years | Longitudinal ascertainment of treatment-emergent CRS and neurologic toxicity |
For a fixed-window binary endpoint, the estimand can be stated as the probability that a participant experiences the event during the specified window. For an endpoint assessed through last follow-up, interpretation is more dependent on follow-up duration and event ascertainment. These are not necessarily the same statistical estimand simply because both are reported as percentages.
14. Missing Data, Censoring, and Follow-Up
The ClinicalTrials.gov record does not specify a formal missing-data or imputation strategy, nor do they provide a detailed censoring rule for the registered binary endpoints. It would therefore be inappropriate to attribute a particular imputation method, missing-as-nonresponse rule, or censoring convention to the ZUMA-1 statistical analysis from the ClinicalTrials.gov record alone.
Binary efficacy endpoints
For ORR, missing response assessments can affect the denominator and classification of participants. The prespecified analysis population and handling of unevaluable participants should therefore be established before interpreting a response percentage.
Safety endpoints
For treatment-emergent toxicities, incomplete follow-up can affect the opportunity to observe events. Event definitions and observation windows are therefore essential to interpreting the reported percentage.
15. Randomization and Causal Interpretation
ZUMA-1 is explicitly classified as NON_RANDOMIZED. This is one of the most important statistical characteristics of the study. In a randomized controlled trial, the randomization mechanism supports a causal interpretation of an appropriately analyzed between-arm difference. In a non-randomized study, that design-based protection is absent.
This does not make the observed response or safety data statistically uninformative. It changes the question they can answer. A well-defined cohort can provide evidence about the frequency of responses or adverse events in the studied population. A causal comparison against another treatment requires additional design or analytical assumptions that are not reported in the ClinicalTrials.gov record here.
A cohort response rate describes the observed study population. To interpret a difference between cohorts causally, investigators would need a defensible comparison framework and assumptions addressing why the cohorts can be compared.
16. Multiplicity and Interim Analysis
The ClinicalTrials.gov record identifies a phase 1/2 sequential design and six registered primary endpoints, but they do not provide a formal multiplicity strategy, alpha-spending plan, interim-analysis boundary, or prespecified hypothesis hierarchy.
That absence matters because the six endpoints are not six interchangeable repetitions of the same test. They correspond to different study components and different clinical questions. A formal multiplicity interpretation would require knowing which hypotheses were confirmatory, whether they shared a familywise error budget, whether any analyses were exploratory, and how sequential decisions were prespecified.
What can be said
The registry lists six primary endpoints across phase 1 and phase 2 study components. The design is sequential and non-randomized.
What cannot be inferred
The ClinicalTrials.gov record does not establish an alpha allocation, multiplicity adjustment, interim boundary, or confirmatory hierarchy.
17. Bayesian Methods
No Bayesian statistical method is identified in the ClinicalTrials.gov record. The registry extraction does not provide a Bayesian prior, posterior probability, Bayesian decision rule, or credible interval. Consequently, Bayesian interpretations are not attributed to the ZUMA-1 analysis on this page.
18. Stratification and Subgroups
The ClinicalTrials.gov record does not provide randomized stratification factors or numerical subgroup estimates. Because allocation is non-randomized, the usual randomized-trial interpretation of baseline stratification does not apply directly to this record.
For a sequential non-randomized study, subgroup analyses can be useful descriptively, but they introduce another layer of uncertainty. A response percentage in a small subgroup may be highly variable, and an apparent difference between subgroups does not establish a treatment interaction unless the study was specifically designed and analyzed to test that interaction.
19. What a Formal Statistical Analysis Would Normally Add
The ClinicalTrials.gov record contains outcome measures but no formal statistical-analysis entries. For educational purposes, the following elements would normally be expected in a complete statistical report of these endpoint types:
| Endpoint type | Typical statistical output | Purpose |
|---|---|---|
| DLT proportion | Event count, analysis denominator, percentage, confidence interval | Quantify early dose-limiting toxicity and its precision |
| ORR | Responders, analysis denominator, response percentage, confidence interval | Quantify the observed tumor-response probability |
| CRS by grade | Grade-specific counts and percentages | Describe both frequency and severity distribution |
| Neurologic toxicity by grade | Grade-specific counts and percentages | Describe frequency and severity distribution |
| Comparative analysis, if prespecified | Effect estimate, confidence interval, and hypothesis test appropriate to the design | Quantify evidence for a difference when a valid comparator exists |
The final row is deliberately conditional. Because the ClinicalTrials.gov record identifies a non-randomized design and do not provide formal statistical analyses, the existence, form, or inferential interpretation of such a comparison cannot be assumed.
20. Limitations
- Non-randomized allocation: the registry classifies allocation as NON_RANDOMIZED, so observed cohort differences cannot automatically be interpreted as causal treatment effects.
- Sequential design: the phase 1/2 structure includes different study components and cohorts, making direct pooling or comparison potentially inappropriate without prespecified methodology.
- Different follow-up windows: the registered maximum durations differ across the primary endpoints, so percentages from different endpoints do not necessarily describe equivalent observation periods.
- No formal statistical analyses in the registry-reported extraction: the registry indicates that results are posted, but no formal statistical analyses were posted from which effect estimates, confidence intervals, or p-values can be reproduced.
- Unknown missing-data rules: the ClinicalTrials.gov record does not identify a formal imputation or unevaluable-participant strategy.
- Unknown multiplicity strategy: the ClinicalTrials.gov record does not identify an alpha-spending procedure, multiplicity adjustment, or formal hierarchy across the six registered primary endpoints.
- Subgroup uncertainty: the ClinicalTrials.gov record does not provide subgroup estimates or interaction tests, so subgroup treatment-effect conclusions cannot be reconstructed.
- Endpoint heterogeneity: DLT, ORR, CRS, and neurologic toxicity answer different clinical questions and should not be combined into a single numerical measure of treatment effect.
21. Why This Trial Matters Statistically
ZUMA-1 is a useful statistical teaching case because it illustrates a setting in which the main analytical challenge is not simply selecting a hypothesis test. The study combines multiple phases, sequential cohorts, binary efficacy and safety endpoints, different follow-up windows, and a non-randomized allocation structure.
| Concept | How it appears in ZUMA-1 |
|---|---|
| Binary endpoint | All six registered primary endpoints are classified as binary in the registry-reported extraction. |
| Response-rate analysis | ORR is defined as participants achieving complete or partial response. |
| Safety endpoint construction | DLT, CRS, and neurologic toxicities use prespecified event definitions and severity classifications. |
| Sequential design | The registry identifies a sequential phase 1/2 design. |
| Non-randomized allocation | The allocation field is explicitly recorded as NON_RANDOMIZED. |
| Multiple cohorts | The primary endpoints cover a phase 1 study, pivotal phase 2 cohorts, and safety-management cohorts. |
| Different estimands | The phase 1 endpoint uses a fixed 30-day window, while phase 2 endpoints extend through last follow-up. |
| Severity grading | CRS and neurologic toxicities are registered by severity grade. |
| Denominator discipline | Safety results are reported as affected participants divided by participants at risk for individual cohorts. |
| Registry versus formal analysis | Results are posted, but the registry-reported statistical-analysis field contains no formal analyses. |
22. Statistical Concepts in This Trial
Learn more about the methods used in this trial:
23. Related Statistical Calculators
24. Sources
- ClinicalTrials.gov: NCT02348216 — ZUMA-1.
- PubMed: PMID 34296427.
- PubMed: PMID 39240498.
- PubMed: PMID 38635762.
- PubMed: PMID 36821768.
- PubMed: PMID 34515338.
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25. Record Summary
ZUMA-1 is a completed phase 1/2, non-randomized, sequential study enrolling 307 participants and evaluating axicabtagene ciloleucel in adult participants with refractory or relapsed aggressive non-Hodgkin lymphoma. Its six registered primary endpoints span early dose-limiting toxicity, overall response rate, and treatment-emergent cytokine release syndrome and neurologic toxicities by severity grade.
Statistically, the most important feature of the record is the distinction between posted outcomes and formal statistical analyses. The ClinicalTrials.gov record confirms that results are posted and identify 28 posted outcome measures, but they contain no entries in the statistical-analysis field. Accordingly, this page focuses on the estimands, endpoint definitions, denominators, follow-up windows, and methods that would normally be used to analyze these binary outcomes rather than introducing numerical effect estimates that are absent from the ClinicalTrials.gov record.