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 A Study of the Pharmacokinetics and Safety of MK-8808 (MK-8808-002) (NCT01390441), a randomized phase 1 study. The primary outcome is Part A: Area Under the Concentration-time Curve From Day 0 to Day 84 (AUC0-84day) After a Single Course of Treatment.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01390441 |
| Phase | Phase 1 |
| Condition | Rheumatoid Arthritis |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 100 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Merck Sharp & Dohme LLC |
| Results posted | Yes |
2. Clinical Question
Population
The study enrolled participants with moderate to severe rheumatoid arthritis who had an inadequate response or intolerance to methotrexate. The primary Part A pharmacokinetic analysis was narrower: it included participants who completed a full course of MK-8808 or MabThera®, had no major protocol violations, had a complete pharmacokinetic profile, and met the stated pre-dose concentration criterion. The registry record lists enrollment as 100.
Intervention
Part A compared MK-8808 at 500 mg/m^2 with MabThera® at 500 mg/m^2. A course consisted of intravenous doses on Day 1 and Day 15. The study also had a Part B that compared 1000 mg doses of MK-8808 with MabThera® and Rituxan®.
Comparator
MabThera® and Rituxan® are identified in the registry record as rituximab products. In Part A, the active comparator was MabThera®. In Part B, the active comparators were MabThera® and Rituxan®. The record describes a randomized, parallel-group, active-comparator design.
Primary question
The primary posted endpoint asked how the amount of MK-8808 in plasma over time, from Day 0 to Day 84 after a single course, compared with the amount for MabThera® in Part A. This is a pharmacokinetic question about drug exposure, not a direct measure of rheumatoid arthritis symptoms or disease control. The reported comparison was a geometric mean ratio with a 90% confidence interval.
3. Trial Design
This was a Phase I randomized, double-blind, active-comparator controlled, parallel-group study of pharmacokinetics, safety, and tolerability in participants with rheumatoid arthritis. The registry record lists quadruple masking. The study had two parts with different dose comparisons: Part A compared MK-8808 and MabThera® at 500 mg/m^2, while Part B compared MK-8808, MabThera®, and Rituxan® at 1000 mg. The record lists enrollment as 100.
In the treatment period, participants received a course of intravenous treatment on Day 1 and Day 15. The arm descriptions also refer to a second optional course at Weeks 26 and 28, followed by treatment-period follow-up to Week 52. Extension-period descriptions indicate additional MK-8808 treatment, but the available arm descriptions are incomplete. Further details of extension eligibility or treatment administration are not reported in the registry record.
The registry record gives a study start of 2011-07 and primary completion of 2014-04. Its status is terminated; the reason for termination is not reported in the registry record. Methotrexate, methylprednisolone, acetaminophen, and loratadine are among the listed interventions, but their dosing and role are not reported in the registry record. Randomization procedures, allocation concealment, and the details of how masking was maintained are also not reported in the registry record.
The primary posted pharmacokinetic outcome concerns Part A participants who completed the specified full course and met additional analysis-population criteria. This selected analysis population should not be assumed to include everyone enrolled. The registry record does not explain how many enrolled participants were excluded from this endpoint analysis or why.
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: For Part B only, positive for rheumatoid factor (RF) or, if negative for RF, positive for anti-cyclic citrullinated protein antibodies at the screening visit.
Treatment Period
| Stage | Part A: MK-8808 500 mg/m^2 / Extension A: MK-8808 1000 mg | Part A: MabThera® 500 mg/m^2 / Extension A: MK-8808 1000 mg | Part B: MK-8808 1000 mg / Extension B: MK-8808 1000 mg | Part B: MabThera® 1000 mg / Extension B: MK-8808 1000 mg | Part B: Rituxan® 1000 mg / Extension B: MK-8808 1000 mg |
|---|---|---|---|---|---|
| STARTED | 23 | 22 | 18 | 19 | 18 |
| COMPLETED | 22 | 21 | 8 | 6 | 7 |
| NOT COMPLETED | 1 | 1 | 10 | 13 | 11 |
Reasons for not completing this period:
| Reason | Part A: MK-8808 500 mg/m^2 / Extension A: MK-8808 1000 mg | Part A: MabThera® 500 mg/m^2 / Extension A: MK-8808 1000 mg | Part B: MK-8808 1000 mg / Extension B: MK-8808 1000 mg | Part B: MabThera® 1000 mg / Extension B: MK-8808 1000 mg | Part B: Rituxan® 1000 mg / Extension B: MK-8808 1000 mg |
|---|---|---|---|---|---|
| Protocol Violation | 0 | 1 | 0 | 0 | 0 |
| Physician Decision | 0 | 0 | 0 | 1 | 0 |
| Lack of Efficacy | 0 | 0 | 0 | 0 | 1 |
| Unknown due to early stopping of study | 0 | 0 | 8 | 11 | 7 |
| Adverse Event | 0 | 0 | 1 | 1 | 2 |
| Withdrawal by Subject | 0 | 0 | 1 | 0 | 1 |
| Lost to Follow-up | 1 | 0 | 0 | 0 | 0 |
Extension Period
| Stage | Part A: MK-8808 500 mg/m^2 / Extension A: MK-8808 1000 mg | Part A: MabThera® 500 mg/m^2 / Extension A: MK-8808 1000 mg | Part B: MK-8808 1000 mg / Extension B: MK-8808 1000 mg | Part B: MabThera® 1000 mg / Extension B: MK-8808 1000 mg | Part B: Rituxan® 1000 mg / Extension B: MK-8808 1000 mg |
|---|---|---|---|---|---|
| STARTED | 15 | 13 | 1 | 1 | 3 |
| COMPLETED | 12 | 12 | 1 | 0 | 3 |
| NOT COMPLETED | 3 | 1 | 0 | 1 | 0 |
Reasons for not completing this period:
| Reason | Part A: MK-8808 500 mg/m^2 / Extension A: MK-8808 1000 mg | Part A: MabThera® 500 mg/m^2 / Extension A: MK-8808 1000 mg | Part B: MK-8808 1000 mg / Extension B: MK-8808 1000 mg | Part B: MabThera® 1000 mg / Extension B: MK-8808 1000 mg | Part B: Rituxan® 1000 mg / Extension B: MK-8808 1000 mg |
|---|---|---|---|---|---|
| Protocol Violation | 3 | 1 | 0 | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: Participants who completed a full course of MK-8808 or MabThera® (two full doses of 500 mg/m\^2 on Days 1 and 15), had no major protocol violations, had a complete pharmacokinetic (PK) profile, had serum MK-8808 or MabThera® concentrations prior to the first dose of the first course not exceeding 5% of Cmax after the first dose of the first course
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 | Part A: MK-8808 500 mg/m^2 | Part A: MabThera® 500 mg/m^2 | Part B: MK-8808 1000 mg | Part B: MabThera® 1000 mg | Part B: Rituxan® 1000 mg | Total |
|---|---|---|---|---|---|---|---|
| Participants analysed | 23 | 22 | 18 | 19 | 18 | 100 | |
| Age, Continuous | years | 51.7 (SD 6.7) | 51.5 (SD 8.4) | 46.4 (SD 10.9) | 48.7 (SD 12.4) | 46.2 (SD 10.5) | 49.1 (SD 9.9) |
| Sex: Female, Male: Female | Participants | 20 | 19 | 14 | 16 | 15 | 84 |
| Sex: Female, Male: Male | Participants | 3 | 3 | 4 | 3 | 3 | 16 |
6. Primary Endpoint
The registry lists the primary outcome as Part A: Area Under the Concentration-time Curve From Day 0 to Day 84 (AUC0-84day) After a Single Course of Treatment, measured over Day 1 (pre- and post-dose), Day 3, Day 5, Day 8, Day 15, Day 17, Day 19, Day 22, Day 29, Day 43, Day 57, Day 85.
| Element | Registry entry |
|---|---|
| Result type | Geometric Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | hr*mg/mL |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was Part A area under the concentration-time curve from Day 0 to Day 84 after a single course of treatment, abbreviated AUC0-84day. AUC represents the amount of drug in plasma over time: concentrations are collected at intervals, and the area captures both the level of drug and how long it remains measurable during the stated period. The record lists sampling from Day 1 before and after dosing through Day 85, with additional scheduled collection days in between.
AUC is useful in pharmacokinetic comparisons because it summarizes overall systemic drug exposure rather than focusing on a single concentration measurement. A separate secondary outcome, maximum concentration after the second infusion, addresses the peak observed concentration. Those measures answer related but distinct questions: overall exposure and peak exposure.
The endpoint values are reported as geometric means, with individual-arm 95% confidence intervals. The registry description states that descriptive values and associated dispersion measures are expressed in terms of the factor 10E6, and gives the unit as hr*mg/mL. The analysis population required completion of a full course, no major protocol violations, a complete pharmacokinetic profile, and compliance with the stated pre-dose concentration criterion. AUC is a drug-exposure measure; it is not itself a clinical measure of symptom improvement or safety.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
For the primary Part A endpoint, the geometric mean AUC0-84day was 110.6 for MK-8808 and 110.1 for MabThera®. Their reported individual-arm 95% confidence intervals were 94.51 to 129.3 and 91.97 to 131.8, respectively. The posted analysis gives an ANOVA geometric mean ratio of 1.00, with a 90% confidence interval from 0.87 to 1.16. The endpoint values are reported in hr*mg/mL, expressed in terms of the factor 10E6.
The ratio and interval describe the estimated relative exposure and its uncertainty under the reported analysis. The point estimate is centered at 1.00, while the interval indicates that estimates compatible with the data extend across a range on either side of that point. A confidence interval is not a range containing every participant’s exposure, and it does not by itself establish that two treatments are equivalent. The registry labels the analysis as noninferiority or equivalence, but the noninferiority or equivalence margin is not reported in the registry record. Without that criterion, the interval cannot be judged against a prespecified boundary using the registry information alone.
The separate arm-level confidence intervals describe uncertainty around each geometric mean; they are not the same quantity as the confidence interval for the ratio. The ratio’s confidence interval is the relevant reported interval for the relative comparison. The record reports no p-value for this analysis. A missing p-value does not erase the estimate or interval, but it means the posted result should be read through its reported estimate and precision rather than through a significance threshold.
The endpoint analysis includes 22 participants in the MK-8808 group and 19 in the MabThera® group. These are the analyzed numbers for this outcome, not the registry’s overall enrollment. The criteria for inclusion make clear that the pharmacokinetic result pertains to participants with a complete profile who met the specified conditions. It should not automatically be generalized to every participant enrolled or to other doses and treatment periods.
The record includes additional Cmax outcomes and multiple analyses, but the primary result is the Part A AUC comparison. The endpoint is pharmacokinetic, so it does not establish a difference in clinical response, tolerability, or long-term safety. The terminated status and the absence of a reason for termination in the registry record are relevant context, but do not explain the numerical result or its uncertainty.
9. Statistical Methods Explained
The primary endpoint is continuous pharmacokinetic data summarized as a geometric mean. Geometric means are commonly used for concentration and exposure measures because such measurements can be positively skewed: some observations may be much larger than others, and the distribution may be more naturally described by multiplicative than additive variation. In general, a geometric mean is calculated on a logarithmic scale and then expressed back on the original scale. The registry reports the geometric means, but does not report the detailed transformation or model specification beyond identifying ANOVA for the comparison.
What does the geometric mean ratio represent?
The reported ratio compares the estimated exposure in the MK-8808 group with that in the MabThera® group. A ratio near 1 indicates that the estimated group exposures are close on a relative scale. The posted ratio is 1.00. This is a point estimate, not a guarantee that the true relative exposure is exactly that value. The 90% confidence interval, 0.87 to 1.16, conveys uncertainty around the estimate under the reported model and analysis assumptions.
In general, a confidence interval describes a range of estimates compatible with the observed data and the method used to calculate the interval. It is not an interval for individual participant values, and it is not a probability statement that the true value falls inside this particular interval. The analysis uses a 90% interval for the ratio, whereas each arm’s descriptive geometric mean is accompanied by a 95% confidence interval. Those confidence levels and intervals serve different purposes and should not be interchanged.
How should the noninferiority or equivalence label be read?
The registry identifies the reported comparison as a noninferiority or equivalence analysis and names ANOVA as the method. In general, these approaches evaluate whether a treatment difference or ratio is sufficiently constrained relative to a prespecified clinical or scientific margin. An interval estimate is interpreted against that margin, not merely by checking whether the point estimate is close to a reference value. The margin, the exact hypothesis, and the decision rule are not reported in the registry record. Therefore, the label describes the analysis category but does not provide enough information to independently verify a noninferiority or equivalence conclusion.
ANOVA is a statistical framework for comparing group means under a specified model. For pharmacokinetic data, analyses may use transformed values and report a ratio after returning to the original scale; the registry record does not give the full model details. It does not report covariates, assumptions checks, or procedures for handling deviations from model assumptions. Those details should not be inferred from the method name alone.
Why does over-dispersion matter in general?
In general, over-dispersion means the observed variability is greater than a model expects. If variability is understated, standard errors and confidence intervals can be too optimistic; if a model accounts for the observed variability, uncertainty may be represented more realistically. The registry record does not report an over-dispersion assessment for this endpoint, and no such assessment can be inferred from the interval alone. Pharmacokinetic measures can vary across participants, which is one reason the estimate and its uncertainty should be considered together.
The analysis population is also part of the method. Participants had to complete a full course, have no major protocol violations, have a complete pharmacokinetic profile, and meet the stated pre-dose concentration criterion. In general, a restricted analysis population can differ from the full randomized population, especially if completion or data availability is related to participant characteristics or treatment. The record describes the eligibility conditions for this endpoint but does not report how missing concentration measurements were handled, how many otherwise eligible participants lacked a complete profile, or whether sensitivity analyses were conducted.
The registry lists 11 outcome measures and 8 analyses. In general, assessing multiple outcomes or comparisons can increase the chance of a chance-positive result if each is treated as a separate confirmatory test. Statistical approaches can adjust for multiplicity, define a hierarchy, or distinguish primary from exploratory analyses. The multiplicity strategy is not reported in the registry record. The listed secondary outcomes include Part A and Part B maximum concentration after the second infusion, but their presence does not make the primary AUC outcome a measure of clinical benefit.
Planning illustrations based on an observed effect are not observed power and are not the trial’s own sample-size justification. The registry record does not report a sample-size calculation or its assumptions. In general, a planning calculation depends on the target effect, variability, significance level, allocation, and chosen power. The effect used after observing trial data can be an unstable basis for planning, so such calculations should be treated as illustrations rather than evidence that a trial had adequate power before it began.
10. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| ANOVA | Geometric mean ratio 1.00 | 0.87 to 1.16 | not reported |
The sponsor-reported Part A comparison is an ANOVA estimate of the geometric mean ratio: 1.00, with a 90% confidence interval from 0.87 to 1.16. The registry record also reports the arm-level geometric means and their 95% confidence intervals. These estimates and intervals are the sponsor’s posted analysis results for the primary pharmacokinetic endpoint.
A separate recalculated estimate for this comparison is not reported in the registry record. The record does not flag a discrepancy between the sponsor analysis and a recalculation. Accordingly, the interpretation rests on the posted sponsor analysis, while recognizing that the detailed model specification and the margin for the noninferiority or equivalence assessment are not reported in the registry record. There is no posted p-value for the comparison.
The central statistical question is how precisely the relative exposure is estimated and whether the confidence interval meets the study’s prespecified criterion. The reported interval provides the first piece of information. The criterion needed to independently assess the second is not reported in the registry record. The result should therefore be described as the sponsor-reported ratio and interval, without asserting a conclusion that depends on an unavailable margin.
11. Multiplicity, Missing Data and Analysis Populations
The registry record lists 11 outcome measures and 8 analyses. It identifies the Part A AUC0-84day comparison as the primary outcome, and lists maximum concentration after the second infusion for Part A and Part B among the secondary outcomes. The full outcome hierarchy and the relationship between the listed outcomes and analyses are not reported in the registry record.
When multiple outcomes or comparisons are tested, general statistical practice may control the overall chance of false-positive findings through an adjustment, a prespecified testing sequence, or a distinction between confirmatory and exploratory analyses. The registry record does not report whether a multiplicity adjustment or testing hierarchy was used. This absence matters when interpreting results across multiple endpoints, but does not alter the stated estimate for the primary comparison.
The primary pharmacokinetic population is described through completion, protocol-violation, profile-completeness, and pre-dose concentration criteria. The registry record does not report the full participant flow into this analysis, reasons for exclusion, or the number with missing or unusable concentration measurements. Missing-data handling, imputation, sensitivity analyses, and the analysis population definitions for other outcomes are not reported in the registry record.
The record does not report whether interim analyses were planned or performed, or whether any stopping rules were used. It also does not report the sample-size justification, the anticipated variability, or a prespecified target difference for the primary endpoint. The enrollment listing alone cannot supply those design details. These omissions limit independent assessment of the planned statistical strategy and of how decisions were made over the course of the trial.
Because the primary analysis population is a subset defined by post-randomization data availability and protocol criteria, the result may not describe all randomized participants. That does not make the pharmacokinetic estimate unusable, but it makes clarity about exclusions and missing profiles important. Those details are not reported in the registry record.
12. 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 |
|---|---|---|---|
| Part A: MK-8808 500 mg/m^2 | 1 | 23 | 4.3% |
| Part A: MabThera 500 mg/m^2 | 1 | 22 | 4.5% |
| Part B: MK-8808 1000 mg | 2 | 18 | 11.1% |
| Part B: MabThera 1000 mg | 0 | 19 | 0.0% |
| Part B: Rituxan 1000 mg | 0 | 18 | 0.0% |
| Extension A: MK-8808 500 mg/m^2 /MK-8808 1000 mg | 0 | 15 | 0.0% |
| Extension A: MabThera® 500 mg/m^2 /MK-8808 1000 mg | 0 | 13 | 0.0% |
| Extension B: MK-8808 1000 mg /MK-8808 1000 mg | 0 | 1 | 0.0% |
| Extension B: MabThera® 1000 mg /MK-8808 1000 mg | 0 | 1 | 0.0% |
| Extension B: Rituxan® 1000 mg/MK-8808 1000 mg | 0 | 3 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Part A: MK-8808 500 mg/m^2 | 15 of 23 |
| Part A: MabThera 500 mg/m^2 | 17 of 22 |
| Part B: MK-8808 1000 mg | 11 of 18 |
| Part B: MabThera 1000 mg | 16 of 19 |
| Part B: Rituxan 1000 mg | 13 of 18 |
| Extension A: MK-8808 500 mg/m^2 /MK-8808 1000 mg | 2 of 15 |
Most frequent serious adverse event terms
| Event term | Organ system | Part A: MK-8808 500 mg/m^2 | Part A: MabThera 500 mg/m^2 | Part B: MK-8808 1000 mg | Part B: MabThera 1000 mg | Part B: Rituxan 1000 mg | Extension A: MK-8808 500 mg/m^2 /MK-8808 1000 mg |
|---|---|---|---|---|---|---|---|
| Leukopenia | Blood and lymphatic system disorders | 0 of 23 | 0 of 22 | 1 of 18 | 0 of 19 | 0 of 18 | 0 of 15 |
| Pneumonia | Infections and infestations | 1 of 23 | 0 of 22 | 0 of 18 | 0 of 19 | 0 of 18 | 0 of 15 |
| Lower limb fracture | Injury, poisoning and procedural complications | 0 of 23 | 0 of 22 | 1 of 18 | 0 of 19 | 0 of 18 | 0 of 15 |
| Spinal column stenosis | Musculoskeletal and connective tissue disorders | 0 of 23 | 1 of 22 | 0 of 18 | 0 of 19 | 0 of 18 | 0 of 15 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Part A: MK-8808 500 mg/m^2 | Part A: MabThera 500 mg/m^2 | Part B: MK-8808 1000 mg | Part B: MabThera 1000 mg | Part B: Rituxan 1000 mg | Extension A: MK-8808 500 mg/m^2 /MK-8808 1000 mg |
|---|---|---|---|---|---|---|---|
| Throat irritation | Respiratory, thoracic and mediastinal disorders | 3 of 23 | 1 of 22 | 0 of 18 | 4 of 19 | 0 of 18 | 0 of 15 |
| Influenza | Infections and infestations | 0 of 23 | 3 of 22 | 2 of 18 | 1 of 19 | 0 of 18 | 1 of 15 |
| Headache | Nervous system disorders | 3 of 23 | 2 of 22 | 1 of 18 | 0 of 19 | 1 of 18 | 0 of 15 |
| Infusion related reaction | Injury, poisoning and procedural complications | 3 of 23 | 2 of 22 | 0 of 18 | 0 of 19 | 1 of 18 | 0 of 15 |
| Oropharyngeal pain | Respiratory, thoracic and mediastinal disorders | 1 of 23 | 2 of 22 | 1 of 18 | 1 of 19 | 0 of 18 | 0 of 15 |
| Pruritus | Skin and subcutaneous tissue disorders | 1 of 23 | 1 of 22 | 1 of 18 | 1 of 19 | 1 of 18 | 0 of 15 |
| Anaemia | Blood and lymphatic system disorders | 1 of 23 | 2 of 22 | 0 of 18 | 1 of 19 | 0 of 18 | 0 of 15 |
| Sinus tachycardia | Cardiac disorders | 0 of 23 | 1 of 22 | 1 of 18 | 1 of 19 | 1 of 18 | 0 of 15 |
| Bronchitis | Infections and infestations | 0 of 23 | 1 of 22 | 2 of 18 | 1 of 19 | 0 of 18 | 0 of 15 |
| Hepatitis C | Infections and infestations | 3 of 23 | 1 of 22 | 0 of 18 | 0 of 19 | 0 of 18 | 0 of 15 |
Serious events with the highest arm-level rate: leukopenia (5.6%), lower limb fracture (5.6%), spinal column stenosis (4.5%), pneumonia (4.3%).
The registry reports serious adverse event counts for treatment and extension groups. In Part A, the reported counts were 1 of 23 participants for MK-8808 and 1 of 22 for MabThera®. In Part B, they were 2 of 18 for MK-8808, 0 of 19 for MabThera®, and 0 of 18 for Rituxan®. Extension A reports 0 of 15 and 0 of 13 in its two groups. Extension B reports 0 of 1, 0 of 1, and 0 of 3 in its three groups. These are observed counts in the reported groups, not estimates of comparative risk.
The registry also lists serious-event terms and percentages: Leukopenia, 5.6%; Lower limb fracture, 5.6%; Spinal column stenosis, 4.5%; and Pneumonia, 4.3%. The record does not specify in this summary how these term percentages relate to treatment groups or whether participants could contribute more than one event. Death counts are not reported in the registry record.
In general, small event counts give limited precision for comparing safety between groups. The extension groups include very few participants, so zero reported serious events in a group should not be read as proof that no risk exists. These counts describe the registry’s reported safety data; they do not establish a causal comparison between treatments.
13. What the Result Does, and Does Not, Mean
The primary result is evidence about a specific pharmacokinetic measure: AUC from Day 0 to Day 84 after a single course in the selected Part A analysis population. The posted geometric mean ratio is 1.00, with a 90% confidence interval from 0.87 to 1.16. The result therefore describes estimated relative exposure and its statistical uncertainty under the reported ANOVA analysis.
It does not directly answer whether participants experienced better or worse rheumatoid arthritis symptoms, whether the drugs had the same clinical effect, or whether one treatment was safer. The primary outcome is drug concentration over time, and the secondary outcomes identified in the record are also pharmacokinetic. Safety is reported separately as event counts. No clinical disease-response endpoint is identified as primary in the registry record.
The registry’s noninferiority or equivalence label should be distinguished from a fully verifiable conclusion. Such conclusions depend on a prespecified margin and analysis rules. The margin and detailed decision criteria are not reported in the registry record. The ratio and its interval can be described, but their relationship to an acceptance boundary cannot be independently assessed from the record.
The result also applies to the analyzed Part A population, which required a complete profile and other stated conditions. It should not be extended automatically to participants excluded from that analysis, to the 1000 mg Part B comparisons, or to extension treatment. The study status is terminated, but the reason for termination is not reported in the registry record; that status alone does not explain the endpoint estimate.
Overall, the posted data provide a numerical comparison of exposure between MK-8808 and MabThera® at the Part A dose. They do not settle questions beyond that endpoint, population, and analysis. Interpretation should keep the estimated ratio, its interval, the selected analysis population, and the missing design details in view.
14. Why This Trial Matters Statistically
This trial is statistically informative because it illustrates the difference between comparing a pharmacokinetic quantity and comparing a clinical outcome. AUC summarizes exposure over time, while a clinical outcome would address a patient-level consequence such as disease activity. The registry’s primary endpoint is explicitly an exposure measure, so its interpretation should remain within that scope.
It also illustrates why a ratio and a confidence interval are central to a relative pharmacokinetic comparison. The reported point estimate is 1.00, but the interval from 0.87 to 1.16 communicates uncertainty that the point estimate alone would hide. Individual arm-level intervals and the interval for the ratio answer different statistical questions. Reading them as interchangeable can obscure how the comparison was analyzed.
The registry labels the analysis noninferiority or equivalence, yet does not report the margin. This underscores a general principle: a point estimate close to a reference value does not by itself establish equivalence or noninferiority. The prespecified boundary and analysis plan are essential to interpret such claims. Their absence in the registry record limits independent verification without negating the posted estimate.
Finally, the record makes clear that the primary analysis uses a restricted pharmacokinetic population and that safety counts vary across treatment and extension groups. The details of missing data, multiplicity, and sample-size justification are not reported in the registry record. This combination reinforces the importance of examining the estimate, population, precision, and reporting completeness together rather than relying on a label or a single number.
15. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The primary result is based on 22 participants in the MK-8808 group and 19 in the MabThera® group who met the endpoint analysis criteria. It is not a full randomized-population comparison. Although the registry describes the criteria, it does not report the participant flow, the reasons for exclusions, or the handling of incomplete pharmacokinetic profiles. This limits assessment of whether the analyzed participants differ systematically from those not included.
The registry identifies ANOVA and reports a geometric mean ratio, but the full model specification, transformations, covariates, and model diagnostics are not reported in the registry record. The noninferiority or equivalence margin and detailed decision rule are also not reported. Consequently, the numerical estimate and interval can be described, but the stated analysis category cannot be independently assessed against its intended criterion.
Multiplicity procedures, interim analyses, stopping rules, and the sample-size justification are not reported in the registry record. The study is listed as terminated, but the reason is not reported. These gaps restrict interpretation of the design and analysis process; they do not provide a basis for inferring why the trial ended or whether the result was affected.
The safety summaries contain small counts, particularly in extension groups, and death counts are not reported in the registry record. The serious-event term percentages are not linked to specific treatment groups in the registry record. Thus, the available safety figures have limited use for comparative interpretation. The primary endpoint is pharmacokinetic, and the listed secondary measures are pharmacokinetic as well; the record does not identify a clinical efficacy result as the primary finding.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: A Study of the Pharmacokinetics and Safety of MK-8808 (MK-8808-002) — NCT01390441.
- Registry record last updated 2016-07-20; status last verified 2016-05.
- Results first posted 2016-07-20.
- 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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19. Record Summary
The registry record describes NCT01390441, a Phase I randomized, quadruple-masked, parallel-group study of MK-8808 and rituximab products in participants with rheumatoid arthritis. It lists enrollment as 100 and status as terminated. Part A compared MK-8808 with MabThera® at 500 mg/m^2; Part B included 1000 mg comparisons involving MK-8808, MabThera®, and Rituxan®.
The primary posted outcome was Part A AUC0-84day after a single course. The reported geometric mean ratio was 1.00, with a 90% confidence interval from 0.87 to 1.16. The record also lists Cmax outcomes and safety data. The reason for termination, the noninferiority or equivalence margin, multiplicity procedures, missing-data methods, and sample-size justification are not reported in the registry record.