Alpha¹ by KaimenConfidential

Kaimen Rigor review

Pridopidine in early-stage manifest Huntington's disease: a phase 3 trial.

Reilmann R, Feigin A, Rosser AE, Kostyk SK, Saft C, Cohen Y, Schuring H, Hand R, Tan AM, Chen K, Feng W, Navon-Perry L, Cruz-Herranz A, Syltevik C, Boot D, Squitieri F, Kayson E, Mehra M, Goldberg YP, Geva M, Hayden MR, PROOF-HD study investigators

DOI: 10.1038/s41591-025-03920-3
Record issued: 2026-08-15
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/b24a7338-e4ed-4320-abed-9e4b6b7a9075 is authoritative.

Kaimen Rigor review

Kaimen Rigor reviewed

1.75 / 5

Critical — serious problems across many checks

Interventional Study

Critical

High-priority

How this rating was calculated

Started at 5★ — deductions

IntegrityIntegrity concern ×3−1.5★
ClaimsOverstated claim−0.5★
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★

Model-reported confidence: highReviewer agreement: highEngine: 7.39.0Source: full text

Biggest issues

01Efficacy rests on an unvalidated surrogate endpoint
highOverreachreviewer-assessedFull detail
The primary efficacy claim is based on the surrogate endpoints TFC and cUHDRS, which are clinical rating scales but not hard clinical outcomes. The paper does not provide evidence of target engagement at the tested dose (e.g., PK/PD or receptor occupancy) nor does it cite validated evidence linking these surrogates to long-term clinical outcomes. The claim of potential benefit is based on nominal trends in a subgroup, not on a validated surrogate-to-clinical link.
“The primary and key secondary endpoints, change in total functional capacity (TFC) and composite Unified Huntington’s Disease Rating Scale (cUHDRS) score at week 65, were not met in the overall population.”
Find in source
02Treatment effect not shown to be clinically meaningful
highOverreachreviewer-assessedFull detail
The primary effect sizes are small and not clinically meaningful: TFC difference of -0.18 (95% CI -0.49 to 0.14) and cUHDRS difference of -0.11 (95% CI -0.40 to 0.18), both not statistically significant. Subgroup analyses show nominal differences (e.g., cUHDRS Δ=0.46 at week 26) but these are not anchored to a minimal clinically important difference and are unadjusted for multiplicity.
“The TFC least-squares mean difference between pridopidine and placebo was −0.18 (95% confidence interval −0.49 to 0.14; P = 0.26). The cUHDRS least-squares mean difference between pridopidine and placebo was −0.11 (95% confidence interval −0.40 to 0.18; P =…”
Find in source
03Conclusion reaches beyond the evidence
mediumOverreachreviewer-assessedFull detail
Pridopidine has the potential to address a critical unmet need in HD.
“Taken together, pridopidine has the potential to address a critical unmet need in HD.”
DiscussionFind in source
04Other integrity concern
mediumAuthenticityreviewer-assessedFull detail
Trial NCT03690193 was first submitted to ClinicalTrials.gov on 2018-08-01, after the registered study start date of 2013-12-03. Retrospective registration means the protocol and outcomes were not on the public record before the study ran, which is what prospective registration exists to establish.
NCT03690193
reviewer’s wording

Findings by category

101ArithmeticNumerical inconsistencies 402OverreachOverstated conclusions 103AuthenticityData authenticity concerns 104DisclosureReporting gaps 05AvailabilityNone found 06Copyedit7 minor suggestions

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 phase 3 randomized controlled trial with rigorous design, comprehensive reporting of demographics and ethics, and appropriate statistical methods. The main weaknesses are minor reporting gaps: no explicit power analysis, no explicit outlier handling, a data availability statement that relies on a generic email rather than a named platform, and a few copyedit inconsistencies including a mismatched ClinicalTrials.gov URL and a p-value discrepancy.

Both reviewers classified the study as interventional (phase 3 RCT), and I adopt that classification. The evaluation covered all eight dimensions; several sub-criteria were not applicable (e.g., animal housing, cell line authentication) for this human drug trial. The statistics verification recomputed only 4 tests (all consistent); the rest of the statistical results were not machine-verified and should not be assumed correct. The citation check found no retracted or non-existent references.

Numerical inconsistencies

1 finding · worst low

Values 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

Recomputed 4 tests: 4 consistent, 0 inconsistent; 4 via agent-written checks.

Agent-written checks— recomputed from reported CIs / ratios by code the agent wrote

CONSISTENTreported p = .270 · recomputed p = .263Reviewer 1
Primary TFC difference p-value from CI
“difference −0.18 (95% CI −0.49 to 0.14; P = 0.27)”
Find in source
Taken as given: The CI is a 95% confidence interval for the difference.; The difference is normally distributed (large sample).
Method: Two-sided p-value derived from the estimate and 95% CI using normal approximation.
How we recomputed it: pCI(-0.18, -0.49, 0.14, 0)
CONSISTENTreported p = .454 · recomputed p = .457Reviewer 1
Key secondary cUHDRS difference p-value from CI
“LSMean difference −0.11 (95% CI −0.40 to 0.18); P = 0.454”
Find in source
Taken as given: The CI is a 95% confidence interval for the difference.; The difference is normally distributed (large sample).
Method: Two-sided p-value derived from the estimate and 95% CI using normal approximation.
How we recomputed it: pCI(-0.11, -0.40, 0.18, 0)
CONSISTENTreported p = .270 · recomputed p = .263Reviewer 2
Primary endpoint: TFC change at week 65 (ITT) - difference and p-value
“difference −0.18 (95% CI −0.49 to 0.14; P = 0.27)”
Find in source
Taken as given: The estimate is the difference in LSMeans between pridopidine and placebo.; The 95% CI is two-sided and symmetric on the linear scale.; The p-value is from the same model (MMRM) that produced the CI.
Method: Two-tailed p-value derived from the estimate and 95% CI using the normal approximation (pCI function).
How we recomputed it: pCI(-0.18, -0.49, 0.14, 0)
CONSISTENTreported p = .454 · recomputed p = .457Reviewer 2
Key secondary endpoint: cUHDRS change at week 65 (mITT) - difference and p-value
“LSMean difference −0.11 (95% CI −0.40 to 0.18); P = 0.454”
Find in source
Taken as given: The estimate is the difference in LSMeans between pridopidine and placebo.; The 95% CI is two-sided and symmetric on the linear scale.; The p-value is from the same model (MMRM) that produced the CI.
Method: Two-tailed p-value derived from the estimate and 95% CI using the normal approximation (pCI function).
How we recomputed it: pCI(-0.11, -0.40, 0.18, 0)

lowinternal contradiction
The ClinicalTrials.gov identifier in the Abstract is NCT04556656, but the URL points to NCT03690193, which is a different trial.
“ClinicalTrials.gov identifier: NCT04556656 (https://clinicaltrials.gov/ct2/show/NCT03690193)”
AbstractFind in source
lowinternal contradiction
The Abstract reports P = 0.26 for the primary TFC endpoint, while the Results section reports P = 0.27 for the same endpoint.
Abstract: 'P = 0.26'; Results: 'P = 0.27'
Abstractreviewer’s wording

Overstated conclusions

4 findings · worst high

Conclusions 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
Conclusions overstated beyond the evidenceAssessed
Conclusions only partially backed by the presented evidenceAssessed

7 major claims checked against the paper's own evidence: 1 not fully backed by the presented evidence (unsupported or overstated), 1 only partially supported (evidence backs part of the claim; gaps or caveats remain).

overstatedReviewers 1, 2
Pridopidine has the potential to address a critical unmet need in HD.
The claim is based on exploratory subgroup findings and a plausible mechanism, but the primary endpoints were not met; thus the claim reaches beyond the evidence.
Evidence: Off-ADM subgroup trends and safety profile.
“Taken together, pridopidine has the potential to address a critical unmet need in HD.”
DiscussionFind in source
partialReviewers 1, 2
In the off-ADM subgroup, pridopidine showed favorable trends across multiple measures.
The paper reports nominally significant p-values for some outcomes (e.g., cUHDRS at weeks 26-52) but these are unadjusted for multiplicity and the primary TFC endpoint was not significant; thus the claim is partially supported.
Evidence: Nominal p-values for cUHDRS (P=0.004, 0.014, 0.035) and other measures in the off-ADM subgroup.
In the mITT population off ADMs, pridopidine showed nominally significant benefits in maintaining cUHDRS scores compared with placebo, with the largest differences (Δ) at week 26 (Δ = 0.46, P = 0.004)...
Resultsreviewer’s wording
supportedReviewer 1
Pridopidine did not meet the primary endpoint of change in TFC at week 65 in the overall population.
The reported LSMean difference and CI include zero, and the p-value is non-significant, supporting the claim.
Evidence: LSMean difference −0.18 (95% CI −0.49 to 0.14; P = 0.27)
“The TFC least-squares mean difference between pridopidine and placebo was −0.18 (95% confidence interval −0.49 to 0.14; P = 0.26).”
AbstractFind in source
supportedReviewer 1
Pridopidine did not meet the key secondary endpoint of change in cUHDRS at week 65.
The reported LSMean difference and CI include zero, and the p-value is non-significant, supporting the claim.
Evidence: LSMean difference −0.11 (95% CI −0.40 to 0.18); P = 0.454
“The cUHDRS least-squares mean difference between pridopidine and placebo was −0.11 (95% confidence interval −0.40 to 0.18; P = 0.45).”
AbstractFind in source
supportedReviewer 1
Pridopidine 45 mg twice daily demonstrated a favorable safety and tolerability profile.
The safety data show comparable TEAE rates and no new safety signals, supporting the claim.
Evidence: TEAEs occurred in 85.9% (placebo) vs 82.8% (pridopidine); no treatment-related deaths; no cardiac safety concerns.
Pridopidine 45 mg bid was well-tolerated, with a safety profile broadly comparable with placebo.
Resultsreviewer’s wording
supportedReviewer 2
Pridopidine did not meet its primary or key secondary endpoints in the overall population.
The paper presents the primary and key secondary results showing no significant difference, with p-values > 0.05.
Evidence: Results, Primary outcome and Key secondary outcome: TFC difference -0.18 (95% CI -0.49 to 0.14; P=0.27); cUHDRS difference -0.11 (95% CI -0.40 to 0.18; P=0.454).
The primary and key secondary endpoints... were not met in the overall population.
Abstractreviewer’s wording
supportedReviewer 2
Pridopidine demonstrated a favorable safety and tolerability profile.
The paper reports safety data showing comparable TEAE rates between groups, no treatment-related deaths, and a safety profile consistent with prior studies.
Evidence: Results, Safety and tolerability: TEAEs in 85.9% placebo vs 82.8% pridopidine; no treatment-related deaths; SAEs balanced.
“pridopidine 45 mg twice daily demonstrated a favorable safety and tolerability profile.”
AbstractFind in source

Premise concern: surrogate not validated for clinical benefit; effect size not shown to be clinically meaningful.

INADEQUATESurrogate endpoint
The primary efficacy claim is based on the surrogate endpoints TFC and cUHDRS, which are clinical rating scales but not hard clinical outcomes. The paper does not provide evidence of target engagement at the tested dose (e.g., PK/PD or receptor occupancy) nor does it cite validated evidence linking these surrogates to long-term clinical outcomes. The claim of potential benefit is based on nominal trends in a subgroup, not on a validated surrogate-to-clinical link.
“The primary and key secondary endpoints, change in total functional capacity (TFC) and composite Unified Huntington’s Disease Rating Scale (cUHDRS) score at week 65, were not met in the overall population.”
Find in source
INADEQUATEEffect size
The primary effect sizes are small and not clinically meaningful: TFC difference of -0.18 (95% CI -0.49 to 0.14) and cUHDRS difference of -0.11 (95% CI -0.40 to 0.18), both not statistically significant. Subgroup analyses show nominal differences (e.g., cUHDRS Δ=0.46 at week 26) but these are not anchored to a minimal clinically important difference and are unadjusted for multiplicity.
“The TFC least-squares mean difference between pridopidine and placebo was −0.18 (95% confidence interval −0.49 to 0.14; P = 0.26). The cUHDRS least-squares mean difference between pridopidine and placebo was −0.11 (95% confidence interval −0.40 to 0.18; P = 0.45).”
Find in source

Data authenticity concerns

1 finding · worst medium

An 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.

Other integrity concernAssessed

3 integrity concerns flagged (0 high).

mediumother
Trial NCT03690193 was first submitted to ClinicalTrials.gov on 2018-08-01, after the registered study start date of 2013-12-03. Retrospective registration means the protocol and outcomes were not on the public record before the study ran, which is what prospective registration exists to establish.
NCT03690193
reviewer’s wording

Reporting gaps

1 finding · worst medium

Required 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

Eight Dimensions7 pass · 1 warn

The introduction cites prior clinical trials (HART, MermaiHD, PRIDE-HD) and preclinical evidence for pridopidine's mechanism, acknowledging both strengths and weaknesses. The rationale linking the Sigma-1 receptor agonist activity to potential neuroprotection in HD is logically presented. Limitations of prior research, such as confounding by antidopaminergic medications, are addressed and motivate the sensitivity analysis.

Sub-criteria

prior work citedADEQUATE

premise rationaleADEQUATE

limitations addressedADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The paper establishes a strong scientific premise by citing prior research on HD, pridopidine's mechanism, and previous clinical trials, and clearly links this to the study's objectives.

Evidence

paraphrase[Introduction, paragraphs 1-3]

“Preclinical evidence demonstrates that pridopidine exerts neuroprotective effects through a multimodal action—reducing endoplasmic reticulum stress, promoting calcium homeostasis and stimulating neurotrophic-dependent restoration of synaptic plasticity.”

“These findings supported further evaluation of pridopidine in PROOF-HD (Pridopidine-Outcome-on-Function), a global phase 3, randomized, double-blind, placebo-controlled trial in early adult-onset HD.”

Introduction ¶3Find in source

paraphrase[Introduction, paragraph 4]

“However, given their known side effects, such as parkinsonism, sedation and cognitive impairment, which may confound trial outcomes, a sensitivity analysis was conducted in a subgroup of participants who remained off ADMs.”

PASSReviewer 2· 95% conf

The paper establishes a clear scientific premise by citing prior work on HD, the limitations of current treatments, and the rationale for targeting Sigma-1 receptor with pridopidine.

Evidence

“Clinical trials show oral pridopidine is well-tolerated with a benign safety profile – and may have the potential to preserve functional capacity, cognition and motor function in HD – . In early clinical studies, including the HART and MermaiHD trials ,,, , motor-related endpoints were primary outcomes but were not met.”

Main, paragraphs 2-4Find in source

“Symptomatic treatments exist, but therapies to modify disease progression are urgently needed ,, .”

Main, paragraph 1Find in source

“However, given their known side effects, such as parkinsonism, sedation and cognitive impairment, which may confound trial outcomes ,,, , a sensitivity analysis was conducted in a subgroup of participants who remained off ADMs”

Main, paragraph 5Find in source

Randomization was 1:1, stratified by baseline HD stage and antipsychotic use, with allocation concealed. Blinding is described (double-blind, indistinguishable capsules). A power analysis is not explicitly reported in the text, but the sample size (499) is typical for a phase 3 trial; the absence of an explicit power calculation is a minor gap. Inclusion/exclusion criteria are implied (TFC 7-13 at screening). Missing data were handled via multiple imputation (MNAR) for ITT and observed-case MMRM for mITT. The trial is registered (NCT04556656).

Sub-criteria

controlsN/A

power analysisNOT REPORTED

blinding levelsADEQUATE

outlier handlingADEQUATE

randomization unitADEQUATE

inclusion exclusionADEQUATE

randomization methodADEQUATE

replicate distinctionN/A

independent replicationN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

The trial design is rigorous: randomized, double-blind, placebo-controlled, with stratification, a pre-specified analysis plan, and appropriate handling of missing data and analysis populations.

Evidence

“Randomization was stratified based on baseline HD stage (HD1 TFC 11–13 versus HD2 TFC 7–10) and antipsychotic use at baseline (yes or no). The randomization sequence was generated by the Sponsor’s designated statistical team, and allocation was concealed from site investigators, participants and study staff throughout the trial.”

MethodsFind in source

“Participants in the active arm received pridopidine at the clinically recommended dose of 45 mg bid orally administered as hard gelatin capsules, whereas those in the placebo arm received indistinguishable matching placebo capsules.”

MethodsFind in source

“For ITT analysis: Missing data were imputed using multiple imputations (MI) under the assumption of missing not at random (MNAR).”

Table 2Find in source

PASSReviewer 2· 95% conf

The study design is rigorous: randomized, double-blind, placebo-controlled, with pre-specified inclusion/exclusion criteria, a power analysis, and a clear description of the analysis populations.

Evidence

MethodsFind in source

“aimed to evaluate the efficacy and safety of pridopidine at a dose of 45 mg bid in participants with a TFC score range of 7–13 at screening.”

MethodsFind in source

Sex is reported (51.9% female in ITT). Age is reported (mean 52.5 years). Demographics include age, sex, race/ethnicity is not explicitly reported but is not required for a global trial. Disease characteristics (CAG repeat length, TFC, TMS, etc.) are extensively reported. Species/strain and housing conditions are not applicable for a human trial.

Sub-criteria

demographicsADEQUATE

sex reportedADEQUATE

sex justifiedN/A

age weight healthADEQUATE

housing conditionsN/A

species strain sourceN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Demographic and baseline disease characteristics are comprehensively reported, including age, sex, CAG repeat length, disease stage, and functional scores.

Evidence

“Age (years), mean (s.d.) | 52.6 (11.37) | 52.4 (11.92)”

Table 1Find in source

“Female, n (%) | 126 (51.0) | 129 (53.3)”

Table 1Find in source

PASSReviewer 2· 95% conf

Demographics and baseline disease characteristics are comprehensively reported for the human participants, including age, sex, and disease stage.

Evidence

“In the ITT population, the mean (s.d.) age was 52.5 (11.7) years, CAG repeat length was 43.9 (3.54) and 51.9% of participants were female.”

Results ¶2Find in source

“Age (years), mean (s.d.) | 52.6 (11.37) | 52.4 (11.92)”

Table 1Find in source

“The disease stage distribution showed 41.3% of participants were at stage HD1 (TFC 11–13) and 58.7% were at stage HD2 (TFC 7–10).”

Results ¶2Find in source

The paper names multiple IRBs/IECs (e.g., Western Institutional Review Board, Comité de Protection des Personnes Ile de France VI) and states that the protocol was approved. Written informed consent is explicitly mentioned. Regulatory compliance with the Declaration of Helsinki and ICH-GCP is stated.

Sub-criteria

iacuc statementN/A

informed consentADEQUATE

irb ethics statementADEQUATE

regulatory complianceADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

Ethical approvals are thoroughly documented: named IRBs/IECs approved the protocol, written informed consent was obtained, and compliance with the Declaration of Helsinki and GCP is stated.

Evidence

paraphrase[Methods, Ethical considerations]

“Ethical approvals were obtained from IRBs and IECs at each participating site, including but not limited to the Western Institutional Review Board (USA), Comité de Protection des Personnes Ile de France VI (France), Ethik-Kommission der Ärztekammer Hamburg (Germany)...”

“Written informed consent was obtained from all participants before any study-specific procedures were conducted.”

MethodsFind in source

paraphrase[Methods, Ethical considerations]

“This trial was conducted in accordance with the Declaration of Helsinki and the Council for International Organizations of Medical Sciences International Ethical Guidelines, as well as the International Council for Harmonisation guidelines for Good Clinical Practice.”

PASSReviewer 2· 95% conf

Ethical approvals are adequately reported: the study was conducted in accordance with the Declaration of Helsinki and ICH-GCP, with named IRBs/IECs and informed consent obtained.

Evidence

MethodsFind in source

paraphrase[Methods, Ethical considerations]

“Written informed consent was obtained from all participants before any study-specific procedures were conducted.”

MethodsFind in source

The investigational drug, pridopidine, is identified by name, dose (45 mg bid), and formulation (hard gelatin capsules). Placebo is described as indistinguishable matching capsules. No antibodies, cell lines, or organisms are used. Software (SAS v.9.4) is identified. The study is a clinical trial of a drug, so the investigational product is the key resource.

Sub-criteria

mycoplasma testingN/A

reagents identifiedADEQUATE

organisms identifiedN/A

antibodies identifiedN/A

cell line authenticationN/A

software tools identifiedADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The investigational product (pridopidine) is identified with dose and formulation; no other key biological/chemical resources are used.

Evidence

paraphrase[Methods, Trial design]

“Participants in the active arm received pridopidine at the clinically recommended dose of 45 mg bid orally administered as hard gelatin capsules.”

“All statistical analyses were conducted using SAS v.9.4.”

Statistical analysisFind in source

PASSReviewer 2· 95% conf

The investigational product (pridopidine) is identified with dose and regimen; no other key biological or chemical resources are used, making most sub-criteria not applicable.

Evidence

“Participants in the active arm received pridopidine at the clinically recommended dose of 45 mg bid orally administered as hard gelatin capsules”

MethodsFind in source

“All statistical analyses were conducted using SAS v.9.4.”

Statistical analysisFind in source

The primary analysis uses a mixed-effects model for repeated measures (MMRM), which is named. Assumptions are not explicitly verified but the MMRM is robust to certain violations. Exact p-values are reported for the primary endpoint (P = 0.27) and key secondary (P = 0.454). Effect sizes with 95% CIs are reported. Software (SAS v.9.4) is identified. Data presentation includes figures with individual data points (LSMean ± 95% CI) and per-group n. Mathematical plausibility checks are not applicable for continuous outcomes from a large trial.

Sub-criteria

tests namedADEQUATE

exact p valuesADEQUATE

effect sizes ciADEQUATE

data presentationADEQUATE

software identifiedADEQUATE

assumptions verifiedINADEQUATE

mathematical plausibilityN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Statistical methods are appropriate and well-described: MMRM for primary analysis, exact p-values and CIs reported, software identified, and data presentation follows clinical trial norms.

Evidence

paraphrase[Results, Primary outcome]

“The least-squares mean (LSMean) change was −0.95 (95% confidence interval (CI) −1.18 to −0.72) for placebo and −1.12 (95% CI −1.36 to −0.89) for pridopidine; difference −0.18 (95% CI −0.49 to 0.14; P = 0.27).”

“All statistical analyses were conducted using SAS v.9.4.”

Statistical analysisFind in source

PASSReviewer 2· 95% conf

Statistical methods are appropriate and well-described: MMRM is used for primary analysis, tests are named, effect sizes with CIs are reported, and software is identified. Exact p-values are reported for primary and key secondary endpoints.

Evidence

paraphrase[Methods, Statistical analysis]

“The primary analysis was performed using a maximum likelihood-based mixed-effects model for repeated measures (MMRM).”

“difference −0.18 (95% CI −0.49 to 0.14; P = 0.27)”

ResultsFind in source

“All statistical analyses were conducted using SAS v.9.4.”

Statistical analysisFind in source

The data availability statement describes a managed access process via email to the sponsor, with conditions and a timeframe. However, it does not name a specific repository or platform (e.g., Vivli, YODA) and relies on a request to a generic email address, which is considered 'reported_but_inadequate' per the guidelines. No custom code was developed, so code_sharing is not applicable.

Sub-criteria

code sharingN/A

accession numbersN/A

repository depositN/A

data availability statementINADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

Data availability is well-described with a concrete managed-access process, and code availability is stated (no custom code).

Evidence

“Individual deidentified participant data (IDP), including data dictionaries, will be shared. Related documents including the study protocol, statistical analysis plan (SAP) and informed consent form template will also be available upon request and approval.”

Data availabilityFind in source

“a redacted version of the protocol and SAP are available at https://ghi-muenster.de/protocols/proof-hd and https://ghi-muenster.de/protocols/proof-hd-sap .”

Data availabilityFind in source

“No custom code was developed or used in this study.”

Data availabilityFind in source

WARNReviewer 2· 95% conf

A data availability statement is present but is inadequate because it only offers access 'on request' without a clear, concrete mechanism or platform, and no code was developed.

Evidence

“Requests for access to clinical trial data should be directed to the Sponsor, Prilenia Therapeutics, via email at: info@prilenia.com.”

Data availabilityFind in source

“No custom code was developed or used in this study.”

Data availabilityFind in source

The trial is registered (NCT04556656). Methods are detailed enough for replication. Limitations are explicitly discussed (ADM confounding, COVID-19, subgroup size). Conclusions are appropriately cautious, noting that primary endpoints were not met and subgroup findings are exploratory. Funding and competing interests are disclosed.

Sub-criteria

funding coiADEQUATE

trial registrationADEQUATE

reporting guidelineNOT REPORTED

methods completenessADEQUATE

all outcomes reportedADEQUATE

limitations discussedADEQUATE

conclusions proportionalADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

The manuscript is transparent: registered trial, detailed methods, limitations discussed, conclusions proportional, and funding/COI disclosed.

Evidence

“ClinicalTrials.gov identifier: NCT04556656”

AbstractFind in source

paraphrase[Discussion, paragraph 2]

“The trial was conducted during the COVID-19 pandemic, which impacted global healthcare access. As observed in other neuropsychiatric trials, a higher-than-expected use of ADMs was observed.”

paraphrase[Acknowledgements and Competing interests]

“This trial was sponsored and funded by Prilenia Therapeutics... A.C.-H., L.N.-P., A.M.T., M.G., Y.P.G., Y.C., R.H., K.C., W.F., C. Syltevik, D.B. and H.S. are employees of Prilenia Therapeutics B.V.”

PASSReviewer 2· 95% conf

The manuscript is transparent: methods are detailed, the trial is registered, limitations are discussed, conclusions are proportional, and funding/COI are disclosed.

Evidence

“ClinicalTrials.gov identifier: NCT04556656”

AbstractFind in source

“Although no significant difference with treatment was observed in the off-ADM cohort for TFC, this cohort was smaller than anticipated, and consequently may have limited statistical power.”

Discussion ¶2Find in source

“This trial was sponsored and funded by Prilenia Therapeutics”

AcknowledgementsFind in source

Registered (3 IDs: ClinicalTrials.gov, EudraCT). No reporting guideline cited.

ClinicalTrials.gov

NCT04556656

ClinicalTrials.gov

NCT03690193

EudraCT

2020-002822-10

Broken references and links

None found

References 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 66 references by DOI: 2 verified — 64 no DOI (shown, not verified).

NO DOI
Huntington disease: natural history, biomarkers and prospects for therapeutics
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Factors influencing the total functional capacity score as a critical endpoint in Huntington’s disease research
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Huntington disease: functional capacities in patients treated with neuroleptic and antidepressant drugs
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Effect of deutetrabenazine on chorea among patients with Huntington disease: a randomized clinical trial
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Tetrabenazine as antichorea therapy in Huntington disease: a randomized controlled trial
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Safety and efficacy of tetrabenazine and use of concomitant medications during long-term, open-label treatment of chorea associated with Huntington’s and other diseases
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Antidopaminergic medication is associated with more rapidly progressive Huntington’s disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Antidopaminergic treatment is associated with reduced chorea and irritability but impaired cognition in Huntington’s disease (Enroll-HD)
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Modeling disease progression and placebo response in Huntington’s disease: insights from Enroll-HD and GENERATION HD1 cohorts
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Pridopidine in the treatment of Huntington’s disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Pridopidine activates neuroprotective pathways impaired in Huntington disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
The Sigma-1 receptor mediates the beneficial effects of pridopidine in a mouse model of Huntington disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Pridopidine protects neurons from mutant-huntingtin toxicity via the Sigma-1 receptor
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
The Sigma-1 receptor mediates pridopidine rescue of mitochondrial function in Huntington disease models
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
The Sigma-1 receptor chaperone as an inter-organelle signaling modulator
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Pridopidine reduces mutant huntingtin‐induced endoplasmic reticulum stress by modulation of the Sigma‐1 receptor
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Pridopidine rescues BDNF/TrkB trafficking dynamics and synapse homeostasis in a Huntington disease brain-on-a-chip model
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Sigma-1 and dopamine D2/D3 receptor occupancy of pridopidine in healthy volunteers and patients with Huntington disease: a [ 18 F] fluspidine and [ 18 F] fallypride PET study
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Additional safety and exploratory efficacy data at 48 and 60 months from Open-HART, an open-label extension study of pridopidine in Huntington disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Safety and exploratory efficacy at 36 months in Open-HART, an open-label extension study of pridopidine in Huntington’s disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Pridopidine for the treatment of motor function in patients with Huntington’s disease (MermaiHD): a phase 3, randomised, double-blind, placebo-controlled trial
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Safety and efficacy of pridopidine in patients with Huntington’s disease (PRIDE-HD): a phase 2, randomised, placebo-controlled, multicentre, dose-ranging study
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Effects of pridopidine on functional capacity in early-stage participants from the PRIDE-HD study
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Pridopidine does not significantly prolong the QTc interval at the clinically relevant therapeutic dose
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
A randomized, double-blind, placebo-controlled trial of pridopidine in Huntington’s disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
One-year safety and tolerability profile of pridopidine in patients with Huntington disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Pridopidine for the treatment of ALS—results from the phase 2 Healey ALS platform trial (S5.003)
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Motor, cognitive, and functional declines contribute to a single progressive factor in early HD
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Antidopaminergic medications in Huntington’s disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Antidopaminergic medications and clinical changes in measures of Huntington’s disease: a causal analysis
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Psychopathology in verified Huntington’s disease gene carriers
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Neuropsychiatric aspects of Huntington’s disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Timing and impact of psychiatric, cognitive, and motor abnormalities in Huntington disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
The safety profile of pridopidine, a novel Sigma-1 receptor agonist for the treatment of Huntington’s disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Critical periods of suicide risk in Huntington’s disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Analysis of responder-based endpoints: improving power through utilising continuous components
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Natural history of Huntington disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
The global prevalence of depression, anxiety, and sleep disorder among patients coping with post COVID-19 syndrome (long COVID): a systematic review and meta-analysis
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Antipsychotic prescribing to people with dementia during COVID-19
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Impact of the COVID-19 pandemic on antipsychotic prescribing in individuals with autism, dementia, learning disability, serious mental illness or living in a care home: a federated analysis of 59 million patients’ primary care records in situ using OpenSAFELY
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Austedo (deutetrabenazine), package insert
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Tetrabenazine, package insert
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Risperdal (risperidone), package insert
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Aripiprazole (Abilify Asimtufii), package insert
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Sulpiride and mnemonic function: effects of a dopamine D2 receptor antagonist on working memory, emotional memory and long-term memory in healthy volunteers
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Antipsychotic dose, dopamine D2 receptor occupancy and extrapyramidal side-effects: a systematic review and dose–response meta-analysis
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Antipsychotic-induced akathisia in adults with acute schizophrenia: a systematic review and dose–response meta-analysis
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
A review of the important role of CYP2D6 in pharmacogenomics
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
The effect of potent CYP2D6 inhibition on the pharmacokinetics and safety of deutetrabenazine in healthy volunteers
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Pharmacokinetic and tolerability profile of pridopidine in healthy-volunteer poor and extensive CYP2D6 metabolizers, following single and multiple dosing
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Unified Huntington’s disease rating scale: reliability and consistency
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Pridopidine for the improvement of motor function in patients with Huntington’s disease: a systematic review and meta-analysis of randomized controlled trials
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Pridopidine: overview of pharmacology and rationale for its use in Huntington’s disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Motor outcome measures in Huntington disease clinical trials
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
The dopamine stabilizers ACR16 and (-)-OSU6162 display nanomolar affinities at the σ-1 receptor
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Neuronal Sigma-1 receptors: signaling functions and protective roles in neurodegenerative diseases
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Impairment and restoration of homeostatic plasticity in cultured cortical neurons from a mouse model of Huntington disease
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Sigma-1 receptor ligands: potential in the treatment of neuropsychiatric disorders
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Safety and efficacy of laquinimod for Huntington’s disease (LEGATO-HD): a multicentre, randomised, double-blind, placebo-controlled, phase 2 study
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Interrater reliability of the Unified Huntington’s Disease Rating Scale-Total Motor Score certification
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Addressing bias in responder analysis of patient-reported outcomes
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Comparison of 4 diets of varying glycemic load on weight loss and cardiovascular risk reduction in overweight and obese young adults: a randomized controlled trial
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Co-administration of the dopaminergic stabilizer pridopidine and tetrabenazine in rats
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
NO DOI
Handbook for Good Clinical Research Practice (GCP): Guidance for Implementation
No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).

2 data/code links checked; 2 live.

datahttps://ghi-muenster.de/protocols/proof-hdLIVEHTTP 200
Resolves, but the content could not be matched to the paper.
datahttps://ghi-muenster.de/protocols/proof-hd-sapLIVEHTTP 200
Resolves, but the content could not be matched to the paper.

Copyediting

7 minor

Wording, consistency and formatting errors that need correcting before submission.

No major wording or formatting errors. 7 minor suggestions below.

7 copyedit issues flagged: mostly consistency, typo, clarity.

MINORconsistencyAbstract
“ClinicalTrials.gov identifier: NCT04556656 (https://clinicaltrials.gov/ct2/show/NCT03690193)”
→ Ensure the URL matches the identifier (NCT04556656) or correct the identifier.
The URL points to a different trial number.
MINORtypoResults, Safety and tolerability
“82.8% of participants the pridopidine population”
→ Change to '82.8% of participants in the pridopidine population'.
Missing preposition 'in'.
MINORtypoResults, Impact of pridopidine on functional decline (TFC)
“pridopidine showed a showed a numerically favorable trend”
→ Remove duplicate 'showed a'.
Repetition of phrase.
MINORconsistencyResults, Primary outcome
“P = 0.27”
→ Check consistency with Abstract which states P = 0.26.
Abstract reports P=0.26, Results reports P=0.27 for the same endpoint.
MINORconsistencyAbstract
“ClinicalTrials.gov identifier: NCT04556656 (https://clinicaltrials.gov/ct2/show/NCT03690193)”
→ The URL points to a different trial (NCT03690193). Should be https://clinicaltrials.gov/ct2/show/NCT04556656.
The URL in the abstract does not match the stated identifier.
MINORclarityResults, Safety and tolerability
“82.8% of participants the pridopidine population”
→ Insert 'in' before 'the pridopidine population'.
Missing preposition.
MINORconsistencyResults, Safety and tolerability
“3.6% of in the placebo group”
→ Remove 'of'.
Extra word.

Kaimen Rigor Action ItemsFinal pass before journal submission

The published work is robust overall, but an informed reader should weigh the minor reporting gaps: the lack of an explicit power analysis, the data availability mechanism relying on a generic email, and the internal inconsistencies (ClinicalTrials.gov URL mismatch, p-value discrepancy between Abstract and Results). These do not invalidate the findings but warrant attention; a correction or clarification from the authors would strengthen confidence.

1.
HIGHreporting
Correct the ClinicalTrials.gov URL in the Abstract to match the stated identifier NCT04556656 (currently points to NCT03690193).
The mismatched URL is an internal contradiction that could mislead readers and reviewers about the trial registration.
2.
HIGHstatistics
Reconcile the primary endpoint p-value: Abstract reports P = 0.26 while Results reports P = 0.27 for the same TFC endpoint; ensure both are consistent.
An internal inconsistency in the primary outcome p-value undermines reporting accuracy and could be flagged as an error.
3.
HIGHdata code
Enhance the Data availability statement to name a specific managed-access platform (e.g., Vivli, YODA) or a data access committee with a clear application process, rather than a generic email address.
A concrete data access mechanism is expected for a data-driven clinical trial; the current generic email is less transparent and may not meet journal requirements.
4.
MEDIUMreporting
Add an explicit a priori power analysis or sample size calculation in the Methods to justify the 499 participants, including assumed effect size, alpha, and power.
The absence of a power analysis is a reporting gap that reviewers may question, even though the sample size is typical for a phase 3 trial.
5.
MEDIUMstatistics
Describe how outliers were handled in the statistical analysis, or state that no outliers were excluded.
Explicit outlier handling is part of transparent statistical reporting and is currently not described.
6.
MEDIUMreporting
Add a statement on whether a reporting guideline (e.g., CONSORT) was followed, and if so, provide a reference or checklist.
Referencing CONSORT would enhance reporting transparency and is expected for a clinical trial.
7.
MEDIUMstatistics
Add a statement on the verification of statistical test assumptions (e.g., normality, sphericity) for the MMRM, or note that the method is robust to violations.
Explicitly addressing assumptions strengthens the statistical reporting and preempts reviewer concerns.
8.
MEDIUMreporting
Temper the claim 'Pridopidine has the potential to address a critical unmet need in HD' to reflect that primary endpoints were not met and the evidence is exploratory.
The claim is overstated relative to the primary outcome results; aligning it with the evidence avoids over-claiming.
9.
LOWcopyedit
Fix typo in Results, Safety and tolerability: change '82.8% of participants the pridopidine population' to '82.8% of participants in the pridopidine population'.
Missing preposition is a minor grammatical error that should be corrected for clarity.
10.
LOWcopyedit
Fix duplicate phrase in Results, Impact of pridopidine on functional decline (TFC): remove the repeated 'showed a'.
Repetition is a minor copyedit issue that detracts from readability.
11.
LOWcopyedit
Fix typo in Results, Safety and tolerability: change '3.6% of in the placebo group' to '3.6% in the placebo group'.
Extra word 'of' is a minor grammatical error.

Full text (93,300 chars · analyzed ~80%, head + tail)Analyzed: Aug 15, 2026

RigorReviewer 1

RigorReviewer 2

RigorPre-Submission Reviewer

CopyeditAgent Scribe

CitationsCitation Integrity

StatisticsStatistics Consistency

ReproducibilityLink verification (liveness + content)· no model (rule-based)

PreregistrationDeterministic check· no model (rule-based)

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.”

How stars are deducted

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.

The rating draws on a panel of agents. Three independent Kaimen Rigor reviewers grade the eight dimensions below across several independent passes (the shown verdict is their majority vote — steadier than any single run), isolate the paper’s major claims and check its own evidence backs them, and flag integrity concerns. Alongside them, a citation agent resolves every reference against Crossref, OpenAlex, and Retraction Watch; a statistics agent recomputes reported tests; and rule-based checks verify that declared data/code links actually resolve. Full text is required — an abstract-only submission is not analyzed.

The eight reporting dimensions

Scientific PremisePrior work, rationale, and how it addresses gaps.

Study Design & RigorRandomization, blinding, power, controls, replication.

Biological VariablesSex, age, species/strain, housing, demographics.

Ethical ApprovalsIRB/IACUC approval, informed consent, regulatory compliance.

Key ResourcesAntibodies, cell lines, organisms, software — identified with persistent IDs.

Statistical ReportingNamed tests, exact p-values, effect sizes, plausible summary stats.

Data & Code AvailabilityAvailability statements, repositories, accession numbers, shared code.

Reporting TransparencyMethods, registration, guidelines, outcomes, limitations, funding/COI.

Graded against NIH, MDAR, ARRIVE 2.0, CONSORT, EQUATOR, and RRID guidelines. A dimension that doesn’t apply to the study type is skipped, never penalized.

This Kaimen Rigor review is model-assisted and is not a substitute for formal expert review. It complements human evaluation by surfacing potential methodological concerns — verify each finding against the source.

Pridopidine in early-stage manifest Huntington's disease: a phase 3 trial.

DOI

10.1038/s41591-025-03920-3

Record issued

2026-08-15

Engine

7.39.0

Exported

2026-09-20