IL-6 inhibition with clazakizumab in patients receiving maintenance dialysis: a randomized phase 2b trial.
Chertow GM, Chang AM, Felker GM, Heise M, Velkoska E, Fellström B, Charytan DM, Clementi R, Gibson CM, Goodman SG, Jardine M, Levin A, Lokhnygina Y, Mears J, Mehran R, Stenvinkel P, Wang AY, Wheeler DC, Zoccali C, Ridker PM, Mahaffey KW, Tricoci P, Wolf M
- DOI
- 10.1038/s41591-024-03043-1
- Record issued
- 2026-08-16
- Engine
- 7.39.0
- Exported
- 2026-09-20
Prepared by Alpha1. This document is confidential: it is intended for the recipient it was shared with and must not be redistributed. The live record at alpha1science.com/verify/3e861750-bab4-4392-bbfb-fe1070f86311 is authoritative.
How this rating was calculated
- IntegrityIntegrity concern ×2−1★
- ClaimsEfficacy rests on an unvalidated surrogate endpoint−0.5★
- ClaimsTreatment effect not shown to be clinically meaningful−0.5★
- ReportingData & code availability partially met−0.25★
- Statistics were not checked: no recomputable values were found in this text — no test statistic reported with its degrees of freedom, no effect estimate printed with both a 95% CI and a p-value, and no percentage printed with both its count and its denominator.
- 01Efficacy rests on an unvalidated surrogate endpoint
The primary endpoint is hs-CRP, a surrogate inflammatory biomarker, not a hard clinical outcome. The paper does not demonstrate target engagement at the tested doses (no PK/PD data) and does not cite validated evidence linking hs-CRP reduction to clinical outcomes in this population, though it references CANTOS as indirect support.
“The primary endpoint was the change from baseline in hs-CRP to week 12, expressed as the geometric mean ratio.”
- 02Treatment effect not shown to be clinically meaningful
The effect size is reported as percentage reductions in hs-CRP (86-92%) relative to placebo, but no anchor to clinical meaningfulness is provided. The paper does not establish a minimal clinically important difference for hs-CRP or link the magnitude to improved clinical outcomes.
“Clazakizumab treatment significantly reduced serum hs-CRP concentrations at week 12 by 86%, 90% and 92% relative to placebo”
This Kaimen Rigor review uses Kaimen Rigor reviewers trained on a curated corpus of high-fidelity and retracted papers, with expert supervision and curation. It can still make mistakes; verify each finding against the source before relying on it.
This is a well-conducted and well-reported phase 2b randomized controlled trial with strong methodology, clear ethics approvals, and transparent reporting. The main weakness is the vague data availability statement, which lacks a concrete access mechanism or timeframe. Minor reporting inconsistencies (P < 0.001 vs P < 0.0001) and a typo in the abstract should be corrected.
Both reviewers independently scored all eight dimensions and agreed on all statuses; no divergence in study type (interventional). The statistics verification component could not recompute any tests because only threshold p-values were reported; this does not confirm statistical correctness. The citation check found no retracted or unresolved references.
Numerical inconsistencies
1 finding · worst lowValues that contradict each other or are impossible for the stated sample: recomputed p-values and test statistics, GRIM/GRIMMER checks on summary numbers, percentages against their own counts, totals against their parts, and estimates against their own confidence intervals.
- Internal contradictions in the reported numbersAssessed
- lowinternal contradictionThe abstract reports P < 0.0001 for the primary endpoint, while the results section reports P < 0.001. This is a minor inconsistency in reporting significance thresholds.
Abstract: 'all P < 0.0001' ; Results: 'all P < 0.001'
Abstractreviewer’s wording
Overstated conclusions
2 findings · worst highConclusions that reach past what the paper's own results support — including a significance claim that no longer holds when the statistic is recomputed, and efficacy resting on an unvalidated surrogate endpoint.
- Efficacy rests on an unvalidated surrogate endpointAssessed
- Treatment effect not shown to be clinically meaningfulAssessed
6 major claims checked against the paper's own evidence: all adequately supported.
- supportedReviewers 1, 2Clazakizumab significantly reduced serum hs-CRP concentrations at week 12 compared to placebo.The primary endpoint was met with large reductions and p<0.001, supported by the data.Evidence: Reported reductions of 86%, 90%, 92% vs placebo with P<0.001.
“Clazakizumab treatment signficantly reduced serum hs-CRP concentrations at week 12 by 86%, 90% and 92% relative to placebo in patients randomized to 2.5 mg, 5 mg or 10 mg clazakizumab, respectively (all P < 0.0001), meeting the primary outcome.”
AbstractFind in source - supportedReviewers 1, 2Clazakizumab reduced downstream biomarkers of IL-6 activity (fibrinogen, amyloid A, phospholipase A2, lipoprotein(a)) and increased albumin.The paper reports significant reductions in these biomarkers and increases in albumin, all with p<0.001 or p<0.01.Evidence: Figure 4 shows GMRs with 95% CIs; text states all P<0.001 for biomarkers and P<0.01 for albumin.
“With regard to secondary endpoints, clazakizumab treatment reduced serum fibrinogen, amyloid A, secretory phospholipase A2, and lipoprotein(a) concentrations, as well as increased mean serum albumin concentrations at 12 weeks, relative to placebo.”
AbstractFind in source - supportedReviewers 1, 2The proportion of patients achieving hs-CRP < 2.0 mg/l was significantly higher in clazakizumab groups (79-82%) vs placebo (0%).The reported proportions are consistent with the primary outcome and are plausible.Evidence: Reported proportions in text.
“The proportion of patients who achieved hs-CRP < 2.0 mg l −1 was 79%, 82% and 79% in the 2.5 mg, 5 mg and 10 mg clazakizumab groups, respectively, compared with 0% of placebo-treated patients.”
AbstractFind in source - supportedReviewers 1, 2Clazakizumab was well tolerated with no cases of sustained grade 3 or 4 thrombocytopenia or neutropenia.The safety data show transient grade 3 events that resolved, and no sustained events.Evidence: Safety results section describes two cases of grade 3 thrombocytopenia and two of grade 3 neutropenia that resolved.
“With regard to safety, no cases of sustained grade 3 or 4 thrombocytopenia or neutropenia were observed.”
AbstractFind in source - supportedReviewers 1, 2Serious infections were numerically more frequent in the 10 mg group.The data show 9 serious infections in the 10 mg group vs 2-4 in other groups, supporting the claim.Evidence: Table 2 shows serious infections: 4, 3, 9, 2 for 2.5, 5, 10 mg and placebo.
“Serious infections were seen with similar frequency in the placebo, clazakizumab 2.5 mg and clazakizumab 5 mg groups, but were numerically more frequent in the clazakizumab 10 mg group.”
AbstractFind in source - supportedReviewers 1, 2The results indicate that clazakizumab reduced inflammatory biomarkers associated with cardiovascular events, paving the way for a phase 3 trial.The claim is supported by the biomarker reductions, and the phase 3 trial is mentioned as ongoing.Evidence: Primary and secondary outcomes show significant biomarker reductions.
“The results of this trial indicate that in patients receiving maintenance dialysis, clazakizumab reduced inflammatory biomarkers associated with cardiovascular events.”
DiscussionFind in source
Premise concern: surrogate not validated for clinical benefit; effect size not shown to be clinically meaningful.
- INADEQUATESurrogate endpointThe primary endpoint is hs-CRP, a surrogate inflammatory biomarker, not a hard clinical outcome. The paper does not demonstrate target engagement at the tested doses (no PK/PD data) and does not cite validated evidence linking hs-CRP reduction to clinical outcomes in this population, though it references CANTOS as indirect support.
“The primary endpoint was the change from baseline in hs-CRP to week 12, expressed as the geometric mean ratio.”
- INADEQUATEEffect sizeThe effect size is reported as percentage reductions in hs-CRP (86-92%) relative to placebo, but no anchor to clinical meaningfulness is provided. The paper does not establish a minimal clinically important difference for hs-CRP or link the magnitude to improved clinical outcomes.
“Clazakizumab treatment significantly reduced serum hs-CRP concentrations at week 12 by 86%, 90% and 92% relative to placebo”
Data authenticity concerns
1 finding · worst lowAn adversarial read for patterns associated with data that may not be genuine: results that look too clean, implausibly large effects, duplicated data or images, and methods that do not match the results reported.
- Data look implausibly cleanAssessed
2 integrity concerns flagged (0 high).
- lowdata too cleanThe proportion of patients achieving hs-CRP < 2.0 mg/l is 79%, 82%, and 79% in the three clazakizumab groups, which are very similar and high, but this is plausible given the drug's mechanism and the dose-response is not strictly monotonic.
“The proportion of patients who achieved hs-CRP < 2.0 mg l −1 was 79%, 82% and 79% in the 2.5 mg, 5 mg and 10 mg clazakizumab groups, respectively, compared with 0% of placebo-treated patients.”
ResultsFind in source
Reporting gaps
1 finding · worst mediumRequired detail the manuscript never states — study design, biological variables, ethics approval and consent, key resources, statistical reporting, data and code availability, and overall transparency.
- Data/code availability incompleteAssessed
The introduction cites extensive prior work (CANTOS, lipid-lowering trials, Mendelian randomization) and acknowledges limitations of prior research (e.g., exclusion of ESKD patients from trials). The rationale linking IL-6 to cardiovascular risk in dialysis patients is clearly articulated, and the hypothesis follows logically. Limitations of prior research are addressed by designing a trial specifically in this population.
“Evidence suggests a causal role of activation of the interleukin-6 (IL-6) pathway”
“As such, it is plausible that a therapeutic approach targeting the IL-6 pathway could reduce cardiovascular events and mortality in patients receiving maintenance dialysis.”
“Patients with ESKD have been excluded from most cardiovascular outcome trials”
“Evidence suggests a causal role of activation of the interleukin-6 (IL-6) pathway”
“As such, it is plausible that a therapeutic approach targeting the IL-6 pathway could reduce cardiovascular events and mortality in patients receiving maintenance dialysis.”
“Patients with ESKD have been excluded from most cardiovascular outcome trials”
Randomization method is described (1:1:1:1 ratio, stratified by hs-CRP), blinding is stated (all participants and investigators blinded), and a power analysis is provided (30 per group, >97% power). Inclusion/exclusion criteria are detailed. Outlier handling is addressed through pre-specified analysis sets (PP, mITT, safety). Controls are the placebo group. Independent replication is not applicable for a single pivotal trial, but the primary analysis was independently verified by Stanford Quantitative Sciences Center.
“Eligible patients were randomly allocated in a 1:1:1:1 ratio to placebo or clazakizumab at doses of 2.5 mg, 5 mg or 10 mg. Randomization was stratified by hs-CRP 2–6 mg l −1 or >6 mg l −1 at screening”
“All participants and investigators were blinded to treatment assignment.”
“we determined that a sample size of 30 participants per group (120 in total) would provide >97% power to detect an 80% reduction (GMR to placebo of 0.2, equal to −1.61 on the log scale) in hs-CRP”
“Eligible patients were randomly allocated in a 1:1:1:1 ratio to placebo or clazakizumab at doses of 2.5 mg, 5 mg or 10 mg. Randomization was stratified by hs-CRP 2–6 mg l −1 or >6 mg l −1 at screening”
“All participants and investigators were blinded to treatment assignment.”
“we determined that a sample size of 30 participants per group (120 in total) would provide >97% power to detect an 80% reduction (GMR to placebo of 0.2, equal to −1.61 on the log scale) in hs-CRP comparing clazakizumab relative to placebo, assuming one-sided α of 0.025/3”
Sex is reported for all groups (e.g., 65.6% male in 2.5 mg group). Age is reported as median and range. Demographics include race, ethnicity, BMI, and comorbidities. Since both sexes are enrolled, sex_justified is not applicable. Species/strain and housing conditions are not applicable for a human trial.
“Male, n (%) | 21 (65.6) | 18 (56.3) | 25 (78.1) | 21 (67.7)”
“Age (year), median (range) | 63 (39, 83) | 67 (36, 82) | 63 (31, 83) | 69 (36, 86)”
“Race | White, n (%) | 21 (65.6) | 18 (56.3) | 17 (53.1) | 13 (41.9)”
“Male, n (%) | 21 (65.6) | 18 (56.3) | 25 (78.1) | 21 (67.7)”
“Age (year), median (range) | 63 (39, 83) | 67 (36, 82) | 63 (31, 83) | 69 (36, 86)”
“Race | White, n (%) | 21 (65.6) | 18 (56.3) | 17 (53.1) | 13 (41.9)”
The paper states that Ethics Committees and Institutional Review Boards affiliated with each site approved the protocol, and all participants provided written informed consent. This satisfies both irb_ethics_statement and informed_consent. Regulatory compliance is implied by adherence to Good Clinical Practice (not explicitly named but the trial is registered and conducted under standard regulations).
“Ethics Committees and Institutional Review Boards affiliated with each site approved the protocol.”
“All participants provided written informed consent.”
“Ethics Committees and Institutional Review Boards affiliated with each site approved the protocol.”
“All participants provided written informed consent.”
Clazakizumab is identified as a humanized monoclonal antibody targeting IL-6, with doses specified. The manufacturer (CSL Behring) is implied through funding and author affiliations. Statistical software (SAS 9.4) is identified. Other bench resources (antibodies, cell lines, etc.) are not applicable as this is a clinical trial.
“Clazakizumab is a high-affinity humanized monoclonal antibody that targets the IL-6 ligand”
“We conducted all analyses using SAS version 9.4 (SAS Institute).”
“Clazakizumab is a high-affinity humanized monoclonal antibody that targets the IL-6 ligand”
“We conducted all analyses using SAS version 9.4 (SAS Institute).”
The primary analysis uses MMRM with t-tests, and p-values are reported as <0.001 (exact values not given but acceptable for large effects). Effect sizes are reported as GMRs with 95% CIs. Software is identified. Data presentation includes individual data points (waterfall plots) and per-group n. Mathematical plausibility checks: baseline characteristics appear plausible; no obvious arithmetic errors detected.
“T tests from the MMRM model were used to calculate P values.”
“Serum hs-CRP concentrations at week 12 decreased by 86%, 90% and 92% in patients randomized to 2.5 mg, 5 mg or 10 mg clazakizumab, respectively, and increased by 19% in patients randomized to placebo (all P < 0.001 compared with placebo; Fig. ).”
“Figure shows the individual patient change in hs-CRP (waterfall plots) for all groups”
“T tests from the MMRM model were used to calculate P values.”
“all P < 0.001 compared with placebo”
“GMRs to baseline (95% CI) of serum hs-CRP concentrations”
The data availability statement says data are not currently available and will be made available by request to the sponsor at the end of the trial, pending review committee approval. This is reported_but_inadequate because it lacks a concrete platform or timeframe. No code sharing is mentioned, but no bespoke code is described.
“The data that support the findings of this study are not currently available as the phase 3 study is ongoing. Individual participant data that underlie the results reported will be made available by request to the sponsor at the end of the ongoing trial, provided the proposed use of data has been approved by the review committee.”
“Individual participant data that underlie the results reported will be made available by request to the sponsor at the end of the ongoing trial, provided the proposed use of data has been approved by the review committee.”
Trial registration number is provided (NCT05485961). Methods are comprehensive. Limitations are explicitly discussed (modest sample size, short follow-up, potential for infections). Conclusions are appropriately cautious, noting the need for a phase 3 trial. Funding and competing interests are disclosed. Reporting guideline (CONSORT) is implied by the CONSORT diagram, though not explicitly referenced.
“ClinicalTrials.gov registration: NCT05485961”
“Limitations of the trial include a modest sample size and a relatively short duration of follow-up.”
“G.M.C. has served on the Board of Directors of Satellite Healthcare, a nonprofit dialysis provider. His institution (Stanford University) has received a grant from the trial sponsor, CSL Behring.”
“ClinicalTrials.gov registration: NCT05485961”
“Limitations of the trial include a modest sample size and a relatively short duration of follow-up.”
“G.M.C. has served on the Board of Directors of Satellite Healthcare, a nonprofit dialysis provider. His institution (Stanford University) has received a grant from the trial sponsor, CSL Behring.”
Registered (1 ID: ClinicalTrials.gov). Reporting guideline cited: CONSORT.
Broken references and links
None foundReferences checked against Crossref, OpenAlex and Retraction Watch for retractions and resolvability, plus declared data and code links probed for whether they resolve to content matching the paper.
Checked — nothing surfaced.
Checked 39 references by DOI: 38 verified — 1 no DOI (shown, not verified).
- NO DOI2023 annual data report: epidemiology of kidney disease in the United StatesNo DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
2 data/code links checked; 2 live.
- datahttps://clinicaltrials.gov/study/NCT05485961LIVEHTTP 200Resolves, but the content could not be matched to the paper.
- datahttps://clinicaltrials.gov/ct2/show/NCT05485961LIVEHTTP 200Resolves, but the content could not be matched to the paper.
Copyediting
4 minorWording, consistency and formatting errors that need correcting before submission.
No major wording or formatting errors. 4 minor suggestions below.
4 copyedit issues flagged: mostly consistency, typo, clarity.
- MINORtypoAbstract“signficantly”→ significantlyTypographical error in the abstract.
- MINORconsistencyResults, Primary outcome“all P < 0.001 compared with placebo”→ all P < 0.0001 compared with placeboAbstract states P < 0.0001, but results section states P < 0.001; should be consistent.
- MINORclarityMethods, Statistical analysis“T tests from the MMRM model were used to calculate P values.”→ Clarify that these are two-sided t-tests from the MMRM model.The two-sided nature is mentioned elsewhere but not here.
- MINORconsistencyResults, Primary outcome“all P < 0.001 compared with placebo”→ Ensure consistent use of P < 0.001 vs P < 0.0001 in abstract and results.Abstract states P < 0.0001, results state P < 0.001; should be consistent.
The published work is methodologically robust and generally well-reported; an informed reader should weigh the vague data availability statement and the minor P-value inconsistency as minor limitations. No erratum is warranted for the P-value discrepancy, but the authors should consider issuing a correction for the typo and clarifying the data access plan.
- 1.HIGHdata codeIn the Data availability section, specify a concrete access mechanism (e.g., a data-sharing platform like Vivli or YODA) and a timeframe for when data will be available, moving from 'on request' to a managed-access statement.The current statement is vague and lacks a concrete platform or timeframe, which is a common reviewer concern and limits reproducibility.
- 2.HIGHreportingIn the Methods, explicitly name the reporting guideline followed (e.g., CONSORT) and state that the checklist is submitted, to strengthen transparency.The CONSORT diagram is present but the guideline is not explicitly referenced, which is a minor reporting gap.
- 3.MEDIUMcopyeditIn the Abstract, correct the typo 'signficantly' to 'significantly'.Typographical error in the abstract should be fixed for professionalism.
- 4.MEDIUMcopyeditIn the Results, Primary outcome, ensure consistent use of P < 0.001 vs P < 0.0001 between the abstract and results section.The abstract states P < 0.0001 while the results state P < 0.001; this inconsistency should be resolved.
- 5.MEDIUMstatisticsIn the Methods, Statistical analysis, clarify that the t-tests from the MMRM model are two-sided.The two-sided nature is mentioned elsewhere but not in this sentence, which could cause confusion.
- 6.MEDIUMreportingIn the Methods, describe the blinding of outcome assessors and data analysts explicitly, as only participants and investigators are mentioned.Clarifying who was blinded strengthens the description of blinding procedures.
- 7.MEDIUMreportingIn the Methods, include a statement on whether the trial was conducted in accordance with ICH-GCP or the Declaration of Helsinki.Explicitly naming the ethical standard enhances regulatory compliance reporting.
- 8.MEDIUMreportingIn the Methods, clarify the role of the independent data monitoring committee and whether any interim analyses were pre-specified.This information is important for assessing trial conduct and potential bias.
- 9.MEDIUMdata codeIn the Data availability section, clarify whether the data will be deposited in a public repository after the phase 3 trial, or if it will remain under managed access.Clarifying the long-term data sharing plan improves transparency.
- 10.LOWreportingIn the Discussion, consider adding a note on the generalizability of findings to peritoneal dialysis patients, as they were excluded from this phase.Expanding on this limitation helps readers interpret the applicability of the results.
- 11.LOWdata codeConsider sharing the statistical analysis code (e.g., SAS code) in a public repository to facilitate reproducibility.Sharing code enhances reproducibility, though it is not strictly required.
- 12.LOWreportingProvide a CONSORT checklist as supplementary material to confirm adherence to reporting standards.A checklist would strengthen the reporting transparency claim.
The star rating is the report’s one-glance summary. Every paper starts at 5★ and loses stars for the concrete problems the review finds — so a rating is never a vague average, it’s a running total you can read line by line under “How this rating was calculated.”
- Reporting — 8 dimensionseach dimension that fully fails−½★
- each dimension partially met−¼★
- Statistics · Integrity · Claimseach serious problem−1★
- each medium problem−½★
- Citationseach retracted or unverifiable reference−¼★
- Copyeditonly when the manuscript needs a full edit−½★
The rating never drops below 1★, and a demonstrable critical failure (an impossible statistic, a proven ethics violation) caps it at 1★ on its own — so the stars can never look healthy when the verdict is CRITICAL.
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