Safety, Tolerability and PK of Intravenous (IV) ETI-204 Alone and in Presence of Ciprofloxacin in Adult Volunteers: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety, Tolerability and PK of Intravenous (IV) ETI-204 Alone and in Presence of Ciprofloxacin in Adult Volunteers (NCT01952444), a randomized phase 1 study. The primary outcome is Number of Participants Who Experienced Adverse Events.

2. Clinical Question

The question is specifically about safety, tolerability, and pharmacokinetics under the study conditions, rather than whether either regimen treats inhalational anthrax. The listed trial was Phase 1 and involved adult volunteers; the record does not establish that its results describe people with anthrax or other patient populations. Comparing the groups can describe the observed contrast in this study, but the small group sizes and uncertainty around the estimate matter when interpreting how precisely the contrast is known. The pharmacokinetic outcomes address measured concentrations and related exposure characteristics, not clinical benefit.

3. Trial Design

This was a completed Phase 1, randomized, open-label, parallel-group study sponsored by Elusys Therapeutics. The registry lists enrollment of 40. Participants were assigned to ETI-204 with ciprofloxacin or ETI-204 alone. The primary safety population consisted of randomized subjects who received study drug. For the primary adverse-event outcome, the posted group sizes were 20 in each arm.

The ETI-204 dose was a single intravenous infusion of 16 mg/kg over 90 minutes on Day 1 in both groups. In the combination group, the ETI-204 infusion was immediately followed by intravenous ciprofloxacin at 400 mg, infused over 60 minutes. Oral ciprofloxacin at 750 mg every 12 hours was scheduled from Day 2 to Day 8, followed by a final dose on the morning of an unspecified day. The registry record does not complete that schedule description. The ETI-204-alone group had no ciprofloxacin listed in its arm description.

The open-label design means masking was not used. Randomization and parallel groups support a concurrent comparison, but the registry record does not report the randomization method, allocation concealment, or the original design assumptions. The precise protocol for handling deviations from assigned treatment is not reported in the registry record. The listed study dates are 2013-10-29 for start and 2014-04-09 for primary completion; the status is completed.

The primary outcome was the number of participants experiencing adverse events. The description says safety assessments included vital signs, clinical laboratory tests, ECGs, physical assessments, skin assessments, infusion site assessments, and adverse events. Pharmacokinetic outcomes included ETI-204 concentration and exposure measures collected over the stated visits and times. Although the registry lists 10 outcome measures, it posts results for 9 secondary outcomes, and the number of reported statistical analyses is 0. The registry record does not report a detailed statistical analysis plan.

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

Analysis population for the primary outcome, as defined in the registry: All randomized subjects who received study drug were included in the Safety Population.

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 Who Experienced Adverse Events, measured over Up to 71 days or 101 days (30 days after the final study visit) for subjects with ongoing adverse events at the final study visit, for each group..

The primary endpoint counts participants who experienced adverse events. It is a safety measure: each participant contributes to the count if an adverse event was recorded, rather than the measure counting the total number of separate events. The registry describes safety monitoring through vital signs, laboratory tests, ECGs, physical and skin assessments, infusion site assessments, and adverse-event collection. The endpoint timeframe was up to 71 days or 101 days, with the longer timeframe applying to participants with ongoing adverse events at the final study visit.

Counting participants with an event is useful for comparing how commonly any adverse event was recorded in each group. It does not describe event severity, duration, or the number of events per participant, and the combined count does not identify which specific events occurred. Serious adverse events and deaths are reported separately in the registry record. The primary endpoint is therefore an overall safety summary, not a complete account of every aspect of tolerability.

The posted counts are 14 participants in the ETI-204 plus ciprofloxacin group and 13 in the ETI-204-alone group, with 20 participants at risk in each. The risk difference gives an absolute comparison between the groups on the probability scale. The registry does not report an adjusted analysis or a prespecified threshold for interpreting this endpoint. Its meaning should be read alongside the uncertainty interval and the limited number of participants in each group, rather than as a definitive estimate of risk in broader populations.

7. Results Posted in the Registry

• ETI-204: 65.0% (13/20) versus 70.0% (14/20) on control; risk difference -5.0 percentage points (95% CI -34.0 to 24.0), risk ratio 0.93 (0.60–1.43); unadjusted two-proportion z-test p = 0.736.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Maximum Observed Plasma Concentration of ETI-204 (Cmax)

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • ETI-204 Alone: mean 402.00 versus 397.00 on control; difference 5.00 (95% CI -44.56 to 54.56), standardized effect d = 0.06; z-test p = 0.843.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between ETI-204 Alone and the control. The interval gives the range of effects that remain compatible with the data.

Area Under the Concentration-Time Curve From Time 0 to Time of Last Measurable Concentration (AUC0-last))

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • ETI-204: mean 4,514 versus 4,603 on control; difference -89.00 (95% CI -600.73 to 422.73), standardized effect d = -0.11; z-test p = 0.733.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between ETI-204 and the control. The interval gives the range of effects that remain compatible with the data.

Area Under the Concentration-Time Curve From Time 0 to Infinity (AUC0-inf)

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • ETI-204 Alone: mean 4,891 versus 4,990 on control; difference -99.00 (95% CI -711.96 to 513.96), standardized effect d = -0.11; z-test p = 0.752.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between ETI-204 Alone and the control. The interval gives the range of effects that remain compatible with the data.

The posted secondary results concern ETI-204 pharmacokinetics. They include measures of observed concentration, timing of the maximum concentration, exposure over different intervals, half-life, clearance, and distribution volumes. The results posted with numerical comparisons include maximum observed plasma concentration and the two area-under-the-curve measures. The registry lists a broader set of secondary outcomes than the set with numerical results in the posted record; the remaining measures do not have results presented in the registry record analyzed.

Across the three numerical comparisons, the reported group means are close in relation to the uncertainty expressed by their intervals, and each interval includes zero. This broad pattern is consistent with the primary comparison in the limited sense that neither set of estimates precisely establishes a group difference. It does not mean that the pharmacokinetic findings confirm the safety result: the measures address different outcomes, have different measurement scales, and use different outcome-specific participant counts. They also do not establish that exposure is the same in the two groups.

The secondary results carry less inferential weight because the registry lists no reported analyses and does not describe a prespecified testing hierarchy or adjustment for examining multiple outcomes. Unadjusted results across several measures can produce apparently notable findings by chance, especially when interpreted after examining the data. In this record, the reported p-values are unadjusted, and no analysis plan is available to show how the outcomes were prioritized. The values are most appropriately read as descriptive and exploratory comparisons, with the confidence intervals conveying substantial uncertainty.

The pharmacokinetic findings do not resolve the trial's clinical relevance. The registry does not report a clinical efficacy outcome, a threshold for a clinically important pharmacokinetic difference, or a rationale connecting a particular exposure contrast to patient outcomes. These results describe the measured ETI-204 concentrations and exposures under the study regimens in adult volunteers; broader conclusions are not established by the posted secondary outcomes.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Maximum Observed Plasma Concentration of ETI-204 (Cmax)
• Time to Maximum Observed Plasma Concentration of ETI-204 (Tmax)
• Area Under the Concentration-Time Curve From Time 0 to Time of Last Measurable Concentration (AUC0-last))
• Area Under the Concentration-Time Curve From Time 0 to Infinity (AUC0-inf)
• Terminal Half-life (t1/2)
• Systemic Clearance (CL)
• Volume of Distribution (Vd)
• Volume of Distribution at Steady State (Vss)

9. Statistical Interpretation

10. Statistical Methods Explained

Comparing counts. The primary outcome is binary at the participant level: each participant either experienced an adverse event during the stated observation period or did not. A risk difference compares the proportion with an event in one group with the proportion in the other. Its zero value corresponds to equal observed risks; a negative value in the posted comparison points toward a lower observed risk in the ETI-204-alone group, given the comparison direction. Unlike a relative measure, a risk difference stays on the absolute probability scale. The posted estimate is -0.05. The registry record does not report the sponsor's detailed model or inferential procedure for this endpoint.

Confidence intervals. A confidence interval describes uncertainty around an estimate under the statistical method used. It is not a range that guarantees the true value lies within it, and it does not assign a probability to a particular treatment effect. For the primary risk difference, the interval extends from -0.340 to 0.240. Because it crosses zero and includes values on both sides, the result does not precisely determine the direction of the group contrast. A wide interval relative to a near-zero estimate means that a range of effects remains compatible with the observed data. The registry record does not give enough detail to reconstruct the sponsor's interval method.

Unadjusted p-values. A p-value evaluates the observed data in relation to a null hypothesis, according to a statistical model and its assumptions. It is not the probability that the null hypothesis is true, nor does a larger p-value prove there is no meaningful difference. The primary comparison has an unadjusted p-value of 0.736. The secondary p-values are also unadjusted. The registry record lists no reported analyses, and a detailed testing plan is not reported in the registry record. Consequently, the p-values should not be treated as evidence from a documented confirmatory testing strategy.

Continuous pharmacokinetic outcomes. The secondary pharmacokinetic measures are reported as group means and standard deviations. A mean summarizes the average observed value; a standard deviation describes variation among observed values, rather than uncertainty in the mean itself. The mean difference compares the group means. Its confidence interval indicates the range of differences compatible with the data under the interval method. These summaries do not show the full distribution of individual concentrations or exposure values. The registry record does not report whether the analysis adjusted for covariates, transformed measurements, or applied other distributional methods.

Precision and group size. The primary safety outcome has 20 participants per group. Secondary sample sizes differ by outcome: maximum observed concentration used 18 and 20 participants; the last-measurable-concentration exposure measure used 17 and 20; and the exposure measure to infinity used 16 and 19. The registry record does not explain why the numbers differ, so the differences should not be attributed to a particular cause. Fewer observations generally provide less information, although precision also depends on the variability and scale of the outcome. The intervals for the continuous measures reflect uncertainty in their mean differences; the standard deviations describe the observed variability in each group.

Randomization and masking. Random allocation can reduce systematic differences between groups on average, while a parallel design assigns participants to one group for comparison with the other. The study was open-label, so participants and study personnel were not masked according to the registry. This can matter for subjective reporting and assessment of adverse events, though the registry does not say whether event assessment was blinded or centrally adjudicated. The record does not report the sequence-generation or allocation-concealment procedures.

Multiplicity and analysis population. The registry lists several secondary pharmacokinetic outcomes, but does not report a multiplicity adjustment or a prespecified hierarchy among them. When many outcomes are assessed, unadjusted tests can generate findings that look noteworthy by chance. The record also does not report how missing measurements were handled or whether any analyses used a population different from the posted outcome-specific group sizes. The primary safety population is described as all randomized subjects who received study drug. More detailed analysis-population definitions are not reported in the registry record.

Interpretive boundaries. The reported values are results for this Phase 1 study and its specific dosing schedules. Statistical comparisons describe sampling uncertainty, but they do not resolve questions about clinical importance, representativeness, or unmeasured sources of bias. The record does not report an original statistical analysis plan, sample-size justification, interim analyses, or sponsor-reported statistical analyses. Those absences limit how much can be inferred about whether the posted analyses match the planned analyses. The trial's sample-size illustrations are separate planning calculations based on observed effects, not documentation of the original trial design.

11. Confidence Intervals and Precision

The primary risk-difference estimate is -0.05. Its confidence interval runs from -0.340 to 0.240, spanning values below and above zero. This range is wide enough that the data do not pin down whether the underlying risk difference favors the combination group, favors ETI-204 alone, or is near zero. The interval should be considered with the observed counts of 14 and 13 participants and the 20 participants in each group. The point estimate is not more definitive than its uncertainty interval.

For the pharmacokinetic outcomes, the confidence interval for the maximum-concentration mean difference runs from -44.56 to 54.56. For area under the curve to the last measurable concentration, it runs from -600.7 to 422.7, and for area under the curve to infinity, from -712.0 to 514.0. Each interval includes zero and permits differences in either direction. These estimates are based on outcome-specific group sizes that vary, and the registry does not report why some measurements have fewer participants.

A confidence interval communicates statistical precision, not clinical importance. The registry record does not give a threshold for a clinically important difference in adverse events or pharmacokinetic measures. It also does not report an equivalence margin. Therefore, intervals that include zero cannot be read as proof that the groups are equivalent, and the mean differences cannot on their own establish that any difference matters clinically. The limited group sizes and unadjusted secondary comparisons call for cautious interpretation.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm for 80% power and participants per arm for 90% power; they are not total events. They are illustrations computed from the observed effect, using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The planning effect is the stated fraction of the observed effect. These assumptions describe the illustrations, not the trial's original design assumptions, which are not reported in the registry record.

The 80% power column gives the planned number of participants per arm for a hypothetical study to have an 80% chance of detecting the specified effect under those assumptions. The 90% power column uses a higher target chance of detection. These are prospective planning quantities, not a measure of the probability that the completed trial found a true effect. The sample-size values are not observed power.

Read the rows as planning for the full observed effect, planning for 75% of the observed effect, and planning for 50% of the observed effect. A smaller effect is harder to distinguish from random variation, so the planning calculations require more participants as the target effect becomes smaller. For example, for the primary adverse-event comparison, the figures range from 1,377 participants per arm for 80% power when planning for the observed effect to 5,395 participants per arm when planning for 50% of it. The corresponding 90% figures are 1,842 and 7,222. These are illustrations derived from the observed comparison, not the enrollment target or justification for the completed study.

The trial itself had 20 participants per arm for the primary endpoint. The planning calculations should not be taken to imply that this Phase 1 safety study was designed to meet those hypothetical power targets. Its original sample-size rationale is not reported in the registry record.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.700; treatment proportion p₁ = 0.650; average p̄ = 0.675.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6624 = 1.2982.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6614 = 0.5567.
4. n = (1.2982 + 0.5567)² / (-0.0500)² = 1,376.3, rounded up to 1,377 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.7                          # control proportion
p1 <- 0.65                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(1952444)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 1,377 (80% power), 1,842 (90% power)
 75% of observed effect: n per arm = 2,423 (80% power), 3,243 (90% power)
 50% of observed effect: n per arm = 5,395 (80% power), 7,222 (90% power)
power.prop.test: 1376.3 
Simulated power at n = 1,377 per arm: 0.800 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists multiple secondary pharmacokinetic outcomes, but does not report how the statistical risk from testing multiple outcomes was addressed. A multiplicity strategy might specify a primary comparison sequence, adjust significance thresholds, or define selected outcomes as exploratory. None of those details is reported in the registry record. The posted secondary p-values are unadjusted, and no reported statistical analyses are listed. They should not be interpreted as though a documented multiplicity-controlled analysis had been performed.

The registry record also does not report whether subgroup analyses were planned, whether any interim analyses occurred, or whether stopping rules were used. The absence of these details is not evidence that such procedures were or were not part of the study; their status is not reported in the registry record. The original statistical analysis plan and sample-size justification are likewise not reported.

The primary safety population is described as all randomized subjects who received study drug. The posted primary group sizes are 20 per arm. For the secondary pharmacokinetic outcomes, the reported participant counts vary by outcome. The registry record does not explain the variation, describe missing-data handling, or state whether participants with incomplete measurements were excluded, imputed, or handled by another method. It is therefore not possible to determine from the record why the outcome-specific counts differ or whether missingness could affect the comparisons.

The record does not report whether the primary analysis used an intention-to-treat approach, a per-protocol population, or another population beyond the stated safety population. It also does not give methods for handling protocol deviations or withdrawals. Such details matter because analysis populations and missing-data assumptions can influence both estimates and their uncertainty. Without those details, the posted summaries can be described as recorded, but their full analytic context remains uncertain.

These gaps limit assessment of whether the results follow a prespecified confirmatory plan. They do not change the posted counts or estimates, but they constrain how confidently the secondary comparisons can be treated as planned tests rather than descriptive findings.

15. 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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports zero serious adverse events among 20 participants at risk in the ETI-204 plus ciprofloxacin group and zero among 20 at risk in the ETI-204-alone group. It also reports zero deaths in each group. These are counts observed during the study's reported safety follow-up; they do not establish that serious events or deaths could not occur in a larger population or over a different observation period.

Other adverse events were reported for 14 of 20 participants in the combination group and 13 of 20 participants in the ETI-204-alone group. These broader adverse-event counts are distinct from serious adverse events. A participant can contribute to the count of participants with an adverse event without that event meeting the serious-event category. The registry record does not provide serious adverse-event terms, and it does not identify the specific non-serious events in the registry record analyzed.

The safety monitoring description includes clinical and physical assessments as well as adverse-event collection. The stated endpoint timeframe was up to 71 days or 101 days for subjects with ongoing adverse events at the final study visit. Interpretation should remain tied to this study's small volunteer groups, follow-up description, and posted counts.

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

The posted results describe what was observed in a randomized Phase 1 study of ETI-204 alone and in combination with ciprofloxacin among adult volunteers. The primary safety outcome records participants with adverse events, and the group counts were similar in numerical terms. The estimated risk difference was -0.05, but its confidence interval spans zero and allows a range of differences in both directions. The estimate therefore does not precisely determine the comparative safety profile.

The record also reports pharmacokinetic summaries for ETI-204. The means and mean differences describe the measured concentrations and exposure outcomes in the participants contributing data. Their confidence intervals include zero, and the results are unadjusted. They do not establish that the regimens produce identical pharmacokinetics, nor do they establish a clinically important difference.

These results do not answer whether ETI-204 treats inhalational anthrax. The registry lists the condition, but describes adult volunteers and reports safety and pharmacokinetic outcomes rather than a clinical efficacy endpoint. The posted findings also do not show whether adverse events were caused by ETI-204, ciprofloxacin, the combination, or other factors; the study comparison and event counts alone cannot establish causation for individual events.

The results do not prove equivalence or noninferiority, because the registry record does not report a margin or such a design. They also do not establish the frequency of events in broader patient populations. The small groups, open-label design, uncertainty intervals, outcome-specific secondary sample sizes, and absence of a detailed statistical analysis plan all constrain interpretation. The most direct reading is descriptive: events and pharmacokinetic values were recorded under the listed regimens, with substantial uncertainty around comparisons.

17. Why This Trial Matters Statistically

This study is statistically useful as an example of the distinction between a point estimate and the precision of that estimate. The primary risk difference is close to zero, but its interval spans values on either side of zero. Reading only the estimate or only the p-value would omit important information about the range of contrasts compatible with the data. The posted group counts and interval together make clear that the comparison is imprecise.

It also illustrates the limits of small early-phase group comparisons. Twenty participants per group can describe observed safety and pharmacokinetic results, but the uncertainty around group differences remains consequential. The absence of reported serious adverse events is a direct description of this trial's observations, not a guarantee about future observations or a larger population.

The secondary results reinforce the importance of separating descriptive findings from confirmatory inference. Several pharmacokinetic outcomes are listed, but the record does not report a testing hierarchy, multiplicity adjustment, or sponsor-reported analysis. Unadjusted comparisons across multiple outcomes should not be treated as independent confirmation of a claim. Different outcome-specific sample sizes also make it important to consider which observations underlie each estimate.

Finally, the planning illustrations demonstrate how assumptions about the target effect and desired power shape hypothetical sample sizes. They are based on observed effects and stated planning assumptions, not the original trial's documented design rationale. Keeping that distinction clear prevents retrospective planning calculations from being mistaken for evidence about the study's actual power or purpose.

18. 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 study groups were small, with 20 participants per arm for the primary safety outcome. This limits precision for a group comparison and makes the uncertainty interval central to interpretation. The study was open-label, which may affect reporting or assessment of adverse events; the registry does not say whether any outcome assessment was masked or independently adjudicated.

Participants were adult volunteers, while the registry lists inhalational anthrax as the condition. The record does not establish that volunteers had the condition or that the results generalize to patients. The trial's safety and pharmacokinetic outcomes do not provide a clinical efficacy comparison.

The registry does not report the original statistical analysis plan, sample-size justification, randomization procedures, multiplicity strategy, missing-data methods, or whether interim analyses occurred. It also does not explain the varying participant counts across the secondary pharmacokinetic results. Those omissions make it difficult to assess whether all posted analyses correspond to planned analyses or how incomplete outcome data were handled.

The primary endpoint aggregates participants with adverse events without detailing event type or severity in the posted primary count. The registry reports zero serious adverse events and zero deaths in both groups, but the small number at risk and defined follow-up do not rule out uncommon events or events outside that observation period. The combination-arm description also ends with an incomplete reference to the timing of its final oral dose, so that schedule detail is not reported in the registry record.

Secondary comparisons are unadjusted, and no reported analyses are listed. Their intervals are compatible with a range of differences, while the record provides no clinical-importance threshold. These factors limit claims about comparative pharmacokinetics or safety beyond the descriptive results.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Safety, Tolerability and PK of Intravenous (IV) ETI-204 Alone and in Presence of Ciprofloxacin in Adult Volunteers — NCT01952444.
• Registry record last updated 2019-04-16; status last verified 2019-01.
• Results first posted 2019-04-08.
• 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.

22. Record Summary

NCT01952444 is a completed Phase 1, randomized, open-label, parallel-group study sponsored by Elusys Therapeutics. It compared a single intravenous dose of ETI-204 alone with ETI-204 followed by intravenous and oral ciprofloxacin in adult volunteers. Registry enrollment was 40.

The primary endpoint counted participants experiencing adverse events. The posted counts were 14 of 20 in the combination group and 13 of 20 in the ETI-204-alone group. The risk-difference estimate was -0.05, with a confidence interval spanning zero. The record also posts pharmacokinetic summaries, but no sponsor-reported statistical analyses are listed.

The findings describe this study's observed safety and pharmacokinetic data. The registry does not report the original sample-size rationale, detailed analysis plan, multiplicity procedures, or missing-data methods. The results do not establish clinical efficacy or equivalence between regimens.