This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Safety and Dose-Finding Study of DTX301 (scAAV8OTC) in Adults With Late-Onset Ornithine Transcarbamylase (OTC) Deficiency (NCT02991144), a non-randomized phase 1, phase 2 study. The primary outcome is Number of Participants With Adverse Events (AEs), Treatment-Emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs), Deaths, and TEAEs Leading to Discontinuation.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02991144 |
| Phase | Phase 1, Phase 2 |
| Condition | Ornithine Transcarbamylase (OTC) Deficiency |
| Allocation | Non-Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 16 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Ultragenyx Pharmaceutical Inc |
| Results posted | Yes |
2. Clinical Question
Population
Adults with late-onset ornithine transcarbamylase (OTC) deficiency. The registry record lists enrollment of 16 and defines the primary safety population as participants who received DTX301. The adverse-event figures use a total denominator of 11; the relationship between that denominator and enrollment is not reported in the registry record.
Intervention
DTX301, also described as scAAV8OTC, was administered as a single intravenous dose across dose-finding cohorts. The record describes reactive corticosteroid taper regimens in the lower-dose cohorts and a prophylactic corticosteroid taper regimen with the 1.0x10^13 GC/kg cohort.
Comparator
There was no randomized control group. The registry describes a non-randomized, open-label study and identifies dose and corticosteroid-regimen cohorts. Comparisons between these cohorts are not like-for-like randomized comparisons.
Primary question
The primary objective was to determine the safety of single intravenous doses of DTX301. The primary outcome covers participants with adverse events, treatment-emergent adverse events, serious adverse events, deaths, and treatment-emergent adverse events leading to discontinuation. The record does not report a controlled estimate of a treatment effect.
In statistical terms, this is a descriptive safety and dose-finding question. The relevant observations are counts of participants with events in the treated cohorts, interpreted alongside the outcome definitions and the period in which events were assessed. Such counts can describe what was recorded in this study, but they do not by themselves establish whether an event was caused by treatment or how the event frequency compares with what would have occurred without treatment.
The registry identifies change in ureagenesis and change in plasma ammonia area under the curve as secondary outcomes. It does not provide their results in the registry record described for this record. Their inclusion therefore does not support conclusions about changes in those measures.
3. Trial Design
NCT02991144 is recorded as a completed Phase 1/2 study with a start date of 2017-07-31 and a primary completion date of 2021-12-16. It was open-label, non-randomized, and described as single-arm in the brief summary. The study evaluated DTX301 in adults with late-onset OTC deficiency and had a stated safety and dose-finding purpose.
The registry lists four dose or regimen cohorts: DTX301 2.0 × 10^12 GC/kg; DTX301 6.0 × 10^12 GC/kg; DTX301 1.0 × 10^13 GC/kg; and DTX301 1.0x10^13 GC/kg with prophylactic corticosteroids. The first three cohort descriptions include a reactive corticosteroid taper regimen. The fourth is identified with a prophylactic corticosteroid taper regimen. The first three descriptions also mention sodium acetate as a tracer to measure ureagenesis. The record does not establish a randomized comparison among these cohorts.
Because participants were not randomly allocated, differences between cohort results may reflect differences in dose or corticosteroid regimen, but also other differences between the participants or their care. Without a randomized control group, a simple contrast among cohorts cannot isolate the effect of dose or regimen. Open-label status also means that participants and study personnel were not masked to treatment assignment.
The registry reports enrollment of 16. The primary outcome defines the Safety Set as all participants who received DTX301, while the posted adverse-event counts give a total denominator of 11. The reason these figures differ is not reported in the registry record. A planned sample-size justification, allocation details beyond non-randomized assignment, and any interim-analysis plan are not reported in the registry record.
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: A total of 27 subjects were screened for the study, 16 of whom were enrolled. Of the 16 participants enrolled, 5 participants discontinued the study before receiving DTX301, and were not assigned to a treatment arm.
Overall Study
| Stage | Cohort 1: DTX301 2.0 × 10^12 GC/kg | Cohort 2: DTX301 6.0 × 10^12 GC/kg | Cohort 3: DTX301 1.0 × 10^13 GC/kg | Cohort 4: DTX301 1.0x10^13 GC/kg + Prophylactic Corticosteroids |
|---|---|---|---|---|
| STARTED | 3 | 3 | 3 | 2 |
| COMPLETED | 3 | 3 | 3 | 2 |
| NOT COMPLETED | 0 | 0 | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Safety Set: all participants who received DTX301.
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.
| Characteristic | Unit | Cohort 1: DTX301 2.0 × 10^12 GC/kg | Cohort 2: DTX301 6.0 × 10^12 GC/kg | Cohort 3: DTX301 1.0 × 10^13 GC/kg | Cohort 4: DTX301 1.0x10^13 GC/kg + Prophylactic Corticosteroids | Total |
|---|---|---|---|---|---|---|
| Participants analysed | 3 | 3 | 3 | 2 | 11 | |
| Age, Continuous | years | 32.3 (SD 11.06) | 27.7 (SD 1.15) | 26.7 (SD 7.09) | 30.5 (SD 13.44) | 29.2 (SD 7.67) |
| Sex: Female, Male: Female | Participants | 1 | 2 | 2 | 2 | 7 |
| Sex: Female, Male: Male | Participants | 2 | 1 | 1 | 0 | 4 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 1 | 0 | 0 | 1 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 3 | 2 | 3 | 2 | 10 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 1 | 0 | 0 | 0 | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): White | Participants | 2 | 3 | 3 | 2 | 10 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 | 0 | 0 |
| Rate of Ureagenesis | μmol*h/kg | 166.293 (SD 28.0167) | 103.329 (SD 76.9798) | 115.492 (SD 71.0753) | 174.678 (SD 210.9140) | 136.791 (SD 88.4373) |
| Area Under the Curve From Time Zero to 24 Hours (AUC0 24) of Plasma Ammonia | μmol*h/L | 1831.78 (SD 1445.240) | 2153.74 (SD 1406.173) | 4444.76 (SD NA) | 1834.39 (SD 1091.019) | 2230.01 (SD 1370.847) |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Adverse Events (AEs), Treatment-Emergent Adverse Events (TEAEs), Serious Adverse Events (SAEs), Deaths, and TEAEs Leading to Discontinuation, measured over AEs Prior to Dosing: From signing the informed consent form (ICF) to first dose of study drug. TEAEs: From first dose of study drug up to End of Study (Week 52)..
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary outcome counts participants with adverse events (AEs), treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), deaths, and TEAEs leading to discontinuation. These categories describe different aspects of safety. An AE is defined as an untoward medical occurrence regardless of its relationship to study product. A TEAE is an event that begins after exposure or a pre-existing event that worsens in intensity or frequency after exposure. An SAE is defined by outcomes or seriousness criteria such as death, immediate life threat, hospitalization, persistent or significant disability, congenital anomaly, or another important medical event in the investigator’s judgment.
Counting participants with events is useful in a safety study because it gives a direct descriptive account of how many people experienced events in the defined population. The registry also describes AE intensity grades and how investigators characterized the relationship of an event to study product. These classifications provide context, but an investigator’s assessment of relatedness is not equivalent to a randomized estimate of causation.
The outcome timeframe distinguishes AEs before dosing, from signing informed consent to first dose, from TEAEs after first dose through End of Study (Week 52). The posted results include counts for serious and other adverse events and deaths. They do not separately provide all of the primary outcome components, including counts for TEAEs leading to discontinuation, in the registry record. Those unreported results cannot be inferred from the available counts.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted adverse-event figures are descriptive counts. In the total row, the registry reports 1 participant with a serious adverse event among 11 at risk and 11 participants with other adverse events among 11 at risk. It also reports 2 deaths in the total row. The cohort rows report no serious adverse events and no deaths in the first three cohorts, and 1 serious adverse event among 2 at risk in the prophylactic-corticosteroid cohort. Each cohort row reports other adverse events in all participants at risk.
These numbers should be read as counts within the registry’s reported denominators, not as results of a randomized comparison. The study was non-randomized and open-label, and no like-for-like control group is described. Cohort differences therefore cannot be attributed to dose or corticosteroid regimen alone. The counts also do not establish whether DTX301 caused any individual event: the AE definition includes occurrences regardless of their causal relationship, and the record describes investigator assessments of relatedness separately.
There is an internal inconsistency in the posted death figures: each listed cohort reports 0 deaths, while the total row reports 2. The record does not explain how those values were reconciled. The overall deaths figure should therefore be presented as reported, with the discrepancy made explicit rather than resolved by assumption.
The safety denominator is also not the same as the enrollment figure: enrollment is 16, while the total adverse-event risk set is 11. The record defines the Safety Set as participants who received DTX301, but the reason for the difference is not reported in the registry record. No conclusion should be drawn about the status or outcomes of participants outside the reported safety denominator.
The total row reports 1 serious adverse event and lists Hyperammonaemic Crisis at 50.0% among the top serious terms. The meaning of that percentage’s denominator is not specified in the registry record described for the record, so it should not be treated as a percentage of all participants. More generally, these data characterize events observed in this study; they do not quantify comparative risk or provide a precise causal estimate.
The registry record lists secondary outcomes concerning change in ureagenesis and plasma ammonia, but their results are not reported in the registry record described for this record. No statistical analyses are listed. Thus, the posted safety counts are the basis for interpretation; no hypothesis-test result or adjusted treatment-effect estimate is available.
9. Statistical Methods Explained
For a binary safety outcome, the basic descriptive quantity is the number of participants who experienced the event, interpreted alongside the number of participants at risk. The registry’s adverse-event results use this count format. It is important to retain both the count and its denominator: the same count can convey different information in groups of different sizes. Here, cohort denominators are small, so each participant’s event status has substantial influence on the cohort count. No confidence intervals are reported in the registry record described for this record.
What does a participant count represent?
A participant count records whether a person met an outcome definition during the specified observation period. It is not necessarily a count of every event episode. One participant may experience more than one event, but a count of participants with at least one event does not show the number, timing, duration, or recurrence of those episodes. The registry’s primary outcome is framed as participants with events, so the reported values should be read as participant counts rather than event totals.
Outcome definitions matter. An AE is counted regardless of whether it is considered related to study product. A TEAE is defined by its timing relative to exposure or worsening after exposure. An SAE is distinguished by serious consequences or investigator judgment under the listed criteria. These categories are not interchangeable, and a participant may meet more than one category. The record’s descriptions of intensity grades and investigator-assessed relationship add classification detail, but the posted counts alone do not show the full event-level information or the individual assessments.
Why does the study design affect interpretation?
Random allocation is a method for balancing known and unknown participant characteristics across treatment groups on average. This study is listed as non-randomized and open-label, with dose and regimen cohorts rather than a randomized control comparison. As a result, differences in counts across cohorts may have multiple explanations. Dose, corticosteroid regimen, participant characteristics, observation, and chance may all be relevant; the registry entries do not allow those explanations to be separated. Descriptive cohort contrasts should not be interpreted as causal dose effects.
Open-label status means treatment assignment was not masked. This can be relevant to safety reporting because awareness of treatment may affect reporting, monitoring, or investigator classification. That is a general design consideration, not evidence that reporting was biased in this study. The registry entries do not report whether any specific bias assessment was performed.
What does a confidence interval add?
In general, a confidence interval describes the statistical uncertainty around an estimated quantity under a specified method. For event counts or proportions, an interval can help readers see how imprecise an estimate may be, particularly when group sizes are small. It does not correct for non-random allocation, incomplete reporting, outcome misclassification, or lack of a control group. No confidence intervals or other uncertainty estimates for these safety counts are reported in the registry record.
Likewise, a p-value would address compatibility between data and a specified statistical model or null hypothesis, not the probability that a treatment works or caused an event. No inferential analyses are listed in the registry entries. Therefore there is no reported p-value to interpret and no basis for describing these cohort counts as statistically significant or non-significant.
How should the event categories be handled?
The primary outcome includes AEs before dosing as well as TEAEs after dosing through End of Study (Week 52). The distinct time windows affect what counts as an event in each category. A pre-dose AE is not automatically a TEAE, and the posted definitions distinguish events already present before exposure from new or worsened events after exposure. The posted results described in the record do not provide a complete breakdown of every primary outcome category and timeframe. Missing component results cannot be derived from the available counts.
The total row and cohort rows should be considered together only with attention to their denominators and the reported inconsistency in deaths. Totals can help describe the record’s overall reported safety count, but they do not repair an unexplained discrepancy among rows. Nor should a total count be treated as an independent confirmation of the cohort values. The reported 2 deaths in the total row alongside 0 deaths in each listed cohort remains unreconciled in the registry record.
What can planning illustrations tell readers?
In general, sample-size planning calculations illustrate how a future study’s size might relate to a chosen effect, variability assumptions, significance level, and power target. They are not observed power and do not alter the evidence from the completed study. The planning assumptions described for this record are illustrations based on an observed effect and specify a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such planning values should not be read as the study’s original design justification: that justification is not reported in the registry record. The posted safety counts are descriptive and do not establish a comparative effect for such planning calculations.
10. Multiplicity, Missing Data and Analysis Populations
The primary outcome contains several related safety components: AEs, TEAEs, SAEs, deaths, and TEAEs leading to discontinuation. The registry also lists secondary outcomes for change in ureagenesis and plasma ammonia area under the curve. When a study evaluates multiple outcomes, multiplicity can matter if formal statistical tests are used, because the chance of at least one apparently unusual result can depend on the number of tests and the analysis strategy. No multiplicity adjustment or testing hierarchy is reported in the registry record. The record lists no analyses, so no correction or testing plan can be assessed.
Missing-data methods are not reported in the registry record. The record defines the Safety Set as all participants who received DTX301, but it does not explain the difference between enrollment of 16 and the adverse-event total denominator of 11. It also does not report whether any participants had incomplete follow-up, how incomplete observation was handled, or whether any outcomes were unavailable. These details should not be inferred from the counts.
The analysis population is described for the primary safety endpoint, but a separate analysis population for the secondary outcomes is not reported in the registry record. The outcome timeframes and definitions are available for the primary safety measures; a fuller account of analysis procedures, missingness, or adjustments is not. Consequently, interpretation should remain focused on the descriptive counts that are reported and should not imply that missing-data or multiplicity concerns were resolved using a particular method.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| DTX301 2.0 × 10^12 GC/kg | 0 | 3 | 0.0% |
| DTX301 6.0 × 10^12 GC/kg | 0 | 3 | 0.0% |
| DTX301 1.0 × 10^13 GC/kg | 0 | 3 | 0.0% |
| DTX301 1.0x10^13 GC/kg + Prophylactic Corticosteroids | 1 | 2 | 50.0% |
| Total | 1 | 11 | 9.1% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| DTX301 2.0 × 10^12 GC/kg | 0 of 3 |
| DTX301 6.0 × 10^12 GC/kg | 0 of 3 |
| DTX301 1.0 × 10^13 GC/kg | 0 of 3 |
| DTX301 1.0x10^13 GC/kg + Prophylactic Corticosteroids | 0 of 2 |
| Total | 2 of 16 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| DTX301 2.0 × 10^12 GC/kg | 3 of 3 |
| DTX301 6.0 × 10^12 GC/kg | 3 of 3 |
| DTX301 1.0 × 10^13 GC/kg | 3 of 3 |
| DTX301 1.0x10^13 GC/kg + Prophylactic Corticosteroids | 2 of 2 |
| Total | 11 of 11 |
Most frequent serious adverse event terms
| Event term | Organ system | DTX301 2.0 × 10^12 GC/kg | DTX301 6.0 × 10^12 GC/kg | DTX301 1.0 × 10^13 GC/kg | DTX301 1.0x10^13 GC/kg + Prophylactic Corticosteroids | Total |
|---|---|---|---|---|---|---|
| Hyperammonaemic Crisis | Metabolism and nutrition disorders | 0 of 3 | 0 of 3 | 0 of 3 | 1 of 2 | 1 of 11 |
Most frequent non-serious adverse event terms
| Event term | Organ system | DTX301 2.0 × 10^12 GC/kg | DTX301 6.0 × 10^12 GC/kg | DTX301 1.0 × 10^13 GC/kg | DTX301 1.0x10^13 GC/kg + Prophylactic Corticosteroids | Total |
|---|---|---|---|---|---|---|
| Headache | Nervous system disorders | 1 of 3 | 0 of 3 | 2 of 3 | 2 of 2 | 5 of 11 |
| Hypertension | Vascular disorders | 1 of 3 | 0 of 3 | 1 of 3 | 1 of 2 | 3 of 11 |
| Cushingoid | Endocrine disorders | 1 of 3 | 0 of 3 | 1 of 3 | 0 of 2 | 2 of 11 |
| Vomiting | Gastrointestinal disorders | 1 of 3 | 0 of 3 | 0 of 3 | 1 of 2 | 2 of 11 |
| Fatigue | General disorders | 1 of 3 | 0 of 3 | 1 of 3 | 0 of 2 | 2 of 11 |
| Feeling Abnormal | General disorders | 0 of 3 | 0 of 3 | 1 of 3 | 1 of 2 | 2 of 11 |
| Nasopharyngitis | Infections and infestations | 0 of 3 | 1 of 3 | 0 of 3 | 1 of 2 | 2 of 11 |
| Exposure To Sars-Cov-2 | Injury, poisoning and procedural complications | 0 of 3 | 0 of 3 | 0 of 3 | 2 of 2 | 2 of 11 |
| Hepatic Enzyme Increased | Investigations | 1 of 3 | 0 of 3 | 1 of 3 | 0 of 2 | 2 of 11 |
| Liver Function Test Increased | Investigations | 0 of 3 | 0 of 3 | 0 of 3 | 2 of 2 | 2 of 11 |
Serious events with the highest arm-level rate: hyperammonaemic crisis (50.0%).
The serious adverse-event figures are counts of participants, not counts of all serious-event episodes. The total row reports 1 participant with a serious adverse event among 11 at risk. The first three cohort rows each report 0 among their respective risk sets, while the prophylactic-corticosteroid cohort reports 1 among 2 at risk. These small denominators mean the cohort counts offer limited precision and should not be treated as stable estimates of event frequency.
The listed top serious term is Hyperammonaemic Crisis at 50.0%. The registry entries do not specify the denominator for this percentage. It should therefore be read as the listed percentage for that term, without assuming it represents a share of all participants, all events, or a particular cohort.
The total row reports 2 deaths, although every listed cohort reports 0 deaths. This discrepancy is not explained in the registry record. It is not appropriate to choose one version as correct or to reconcile the entries by calculation. The other-adverse-event counts are reported for all participants at risk within each cohort and in the total row; those counts should not be confused with serious adverse events. The record’s definitions distinguish seriousness from the broader category of an adverse event.
12. What the Result Does, and Does Not, Mean
The study record documents a non-randomized, open-label evaluation of DTX301 in adults with late-onset OTC deficiency. Its stated primary purpose was safety and dose finding. The posted adverse-event counts describe what was recorded among the reported risk sets, including 1 participant with a serious adverse event in the total row and other adverse events reported for all participants at risk in each cohort. These observations are descriptive evidence about this study population and follow-up.
They do not establish that DTX301 caused or prevented an event. The AE definition explicitly includes events regardless of causal relationship, and the study does not provide a randomized control group for comparison. Nor do the counts establish a comparative safety profile across doses or corticosteroid regimens, because cohorts were not randomized and the denominators are small.
The figures also do not provide a complete account of the primary outcome. The record identifies TEAEs and TEAEs leading to discontinuation as components, but their separate results are not reported in the registry record. Results for the listed secondary outcomes are also not reported. In addition, the unexplained difference between enrollment of 16 and the total safety denominator of 11, together with the conflicting death entries, limits interpretation of the total safety summary.
Statistically, the appropriate conclusion is bounded: the record reports the stated event counts, but does not provide enough information for a causal estimate, a controlled comparison, or a precise estimate of event frequency. The absence of reported analyses is not evidence that no events occurred beyond those listed; it means no further result can be interpreted from the registry entries.
13. Why This Trial Matters Statistically
This trial illustrates why safety counts need to be read with their definitions, denominators, timeframes, and design. A participant count is easy to understand, but it does not convey every detail about event episodes, severity, timing, or causality. The primary outcome includes several distinct categories, and the registry’s definitions help distinguish a broad adverse event from a treatment-emergent event or a serious event.
The design also matters. With open-label, non-randomized cohorts and no randomized control group, observed differences across dose or regimen groups cannot be interpreted as isolated treatment effects. The record’s descriptive format is appropriate context for understanding what was observed, but it does not yield a controlled estimate of comparative safety.
The record highlights the importance of transparent denominators and internally consistent reporting. Enrollment is listed as 16, while the safety outcome total uses 11 at risk, and the reason is not reported. The death count also differs between the cohort rows and total row. These points are not merely presentation details: without reconciliation, readers cannot determine how those entries relate to one another.
Finally, a registry outcome list is not the same as a complete statistical analysis. Although secondary outcomes and multiple safety components are named, their analysis results and the handling of multiplicity or missing data are not reported in the registry record. Keeping those limits explicit helps separate the evidence documented in the record from questions it cannot answer.
14. 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 limitation for interpretation is the absence of random allocation and a randomized control group. The study is open-label and non-randomized, so comparisons across dose and corticosteroid-regimen cohorts are vulnerable to differences beyond the assigned cohort. The registry record does not report an adjusted comparative analysis that would address this limitation.
Denominators require caution. Enrollment is 16, whereas the total safety risk set is 11; the reason for this difference is not reported in the registry record. The death counts are also inconsistent: the total row reports 2, while all listed cohort rows report 0. No reconciliation is reported. These features prevent a complete accounting of the participant flow and the aggregate death result in the registry record described.
The available results are counts, with no reported confidence intervals or inferential analyses. The cohort sizes are small, which limits the precision that can be conveyed by raw counts. The percentage attached to Hyperammonaemic Crisis is listed as 50.0%, but its denominator is not reported in the registry entries.
The record identifies several primary and secondary outcomes, but not all component results are reported. Separate results for TEAEs leading to discontinuation and the listed secondary outcome changes are not reported in the registry record. The record also does not report a multiplicity plan, missing-data handling, sample-size justification, or interim-analysis plan. These limitations constrain interpretation; they do not establish that any particular bias, missingness, or analysis problem occurred.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Safety and Dose-Finding Study of DTX301 (scAAV8OTC) in Adults With Late-Onset Ornithine Transcarbamylase (OTC) Deficiency — NCT02991144.
- Registry record last updated 2023-01-26; status last verified 2023-01.
- Results first posted 2022-12-23.
- 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.
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18. Record Summary
NCT02991144 is a completed, open-label, non-randomized Phase 1/2 study of DTX301 in adults with late-onset OTC deficiency. It is described as a single-arm safety and dose-finding study, with four dose or corticosteroid-regimen cohorts and enrollment of 16. The primary objective was to assess safety after single intravenous doses.
The registry’s primary endpoint counts participants with adverse events, treatment-emergent adverse events, serious adverse events, deaths, and treatment-emergent adverse events leading to discontinuation. The total adverse-event row reports 1 serious adverse event among 11 at risk, other adverse events among 11 at risk, and 2 deaths. Cohort death entries do not agree with the total row, and the reason for the difference between enrollment and the safety denominator is not reported in the registry record.
The record lists secondary outcomes for ureagenesis and plasma ammonia but does not report their results in the registry record described. No analyses are listed. The safety findings therefore remain descriptive and do not constitute a randomized comparison or a causal estimate.