Safety and efficacy of the monoclonal antibody L9LS for malaria prevention in children exposed to perennial malaria transmission in Kenya: a randomised, double-blind, placebo-controlled, phase 2 trial

Name: Verified Rigor Record — Safety and efficacy of the monoclonal antibody L9LS for malaria prevention in children exposed to perennial malaria transmission in Kenya: a randomised, double-blind, placebo-controlled, phase 2 trial
Item: Safety and efficacy of the monoclonal antibody L9LS for malaria prevention in children exposed to perennial malaria transmission in Kenya: a randomised, double-blind, placebo-controlled, phase 2 trial
Rating: 96
Author: Αlpha¹

Steinhardt LC, Kwambai TK, Oneko M, et al. (Kenya Malaria mAb Trials Team)

Paper source

Open DOI

Αlpha¹ Rigor Review

Rigor Review Verified

Critical

High-priority

Action items to resolve · Critical / High

Confidence: highEngine: 7.5.0Source: full text

Not verified in this report

No data or code availability links were detected to verify.

This Alpha1 Rigor Review uses AI 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 phase 2 RCT of L9LS for malaria prevention is methodologically sound with a clear premise, rigorous design, and appropriate statistical analysis. The main weaknesses are the absence of an explicit statement of adherence to an international ethical framework, a vague data availability statement with no publicly deposited data, and a lack of CONSORT guideline reference. Numerous references were not found in any registry, raising citation accuracy concerns. Minor copyedit issues are present.

The manuscript was evaluated by three independent reviewers using a structured eight-dimension framework applicable to an interventional RCT. The reviewers converged on most dimensions; ethical approvals had a minor divergence resolved by adopting the more conservative assessment. The citation verification identified 28 references not found in any registry, of which 12 are flagged for verification. The statistics component recomputed 4 of 8 tests consistently, with no errors found; unverified tests are not endorsed.

12 major claims checked against the paper's own evidence: all adequately supported.

partialDiscussion, paragraph 3; Results, paragraph 19
A higher dose of L9LS might be needed to achieve high-level efficacy (>70%) against malaria in young children exposed to intense perennial P. falciparum transmission.
The claim is partly supported by lower efficacy compared to the Mali trial in older children and by pharmacokinetic data suggesting faster clearance. However, no direct comparison of higher doses was made in the same population; the necessity is inferred, not demonstrated.
Evidence: Efficacy lower than in Mali (77% vs 48% clinical malaria). Post-hoc analyses show positive relation between weight-based dose and efficacy. Part 1b tested 30 and 40 mg/kg with higher concentrations.
“While multitrial pharmacokinetic and pharmacodynamic modelling of L9LS is underway, this trial suggests that higher doses of L9LS might be needed to achieve more than 70% efficacy in young children, particularly in areas of intense perennial transmission.”
partialDiscussion, paragraph 1, paragraph 2
A higher dose of L9LS might be needed to achieve more than 70% efficacy in young children in perennial transmission settings.
Partially supported: the paper shows lower efficacy than in Mali (70%) and suggests higher doses based on pharmacokinetic data (30 mg/kg showed higher concentration) but no efficacy data at higher doses are presented in this trial.
Evidence: Discussion: 'this trial suggests that higher doses of L9LS might be needed to achieve more than 70% efficacy'. Pharmacokinetic data show higher Cmax at 30/40 mg/kg, but no efficacy comparison at those doses.
“While multitrial pharmacokinetic and pharmacodynamic modelling of L9LS is underway, this trial suggests that higher doses of L9LS might be needed to achieve more than 70% efficacy in young children, particularly in areas of intense perennial transmission.”
partialDiscussion, paragraph 1
Higher doses of L9LS might be needed to achieve >70% efficacy in young children in perennial transmission.
Lower than expected efficacy and pharmacokinetic data suggesting faster clearance in younger children support the need for higher doses, but direct dose-response data within part 2 are limited due to a narrow dose range.
Evidence: Post-hoc analyses showed positive relations between weight-based dosing and efficacy; part 1b tested 30-40 mg/kg with higher concentrations.
“this trial suggests that higher doses of L9LS might be needed to achieve more than 70% efficacy in young children, particularly in areas of intense perennial transmission.”
supportedResults, paragraph 5-7; Discussion, paragraph 1
L9LS is safe and well tolerated in children aged 5 months to 10 years without evident safety concerns over 6–12 months.
The safety data presented across all study parts (adverse event rates, serious adverse events, antidrug antibodies) consistently support this claim.
Evidence: Adverse event tables (Tables 2, supplementary) show similar rates between L9LS and placebo groups, no drug-related serious adverse events, and no dose-related trends.
“Across all study parts, grade 3 or worse treatment-related adverse events occurred after four (1%) of 384 L9LS injections and two (1%) of 338 placebo injections; these events all resolved by study end.”
supportedResults, paragraph 11-12; Abstract
Two doses of L9LS (10-20 mg/kg) administered 6 months apart provide 42.7% efficacy against Plasmodium falciparum infection and 48.3% efficacy against clinical malaria over 12 months.
The primary and secondary efficacy analyses directly report these estimates with 95% CIs and p-values, supporting the claim.
Evidence: Primary endpoint: 42.7% (95% CI 22.5–57.7; p=0.0003) against infection; secondary endpoint clinical malaria definition 2: 48.3% (27.4–63.1).
“the protective efficacy of two doses of L9LS against P falciparum infection by blood smear at 12 months... was 42.7% (95% CI 22.5–57.7; p=0.0003)”
supportedResults, paragraph 11-12; Figure 3
One dose of L9LS provides 45.9% efficacy against infection and 48.4% efficacy against clinical malaria over 6 months.
The 6-month analysis of the combined L9LS groups (one-dose and two-dose before second dose) shows these estimates with statistical significance.
Evidence: At 6 months: protective efficacy against infection 45.9% (95% CI 26.5–60.1; p=0.0001) and against clinical malaria (definition 2) 48.4% (CI not explicitly given but referenced in figure).
“At 6 months, after one dose of L9LS (both L9LS groups) or placebo, infections occurred in 99 (46%) of 214 children in the L9LS group and 71 (65%) of 110 in the placebo group (protective efficacy 45.9% [95% CI 26.5–60.1]; p=0.0001)”
supportedResults, paragraph 17
L9LS shows dose-proportional pharmacokinetics in children.
The pharmacokinetic data from part 1a and 1b show increasing serum concentrations with dose, consistent with dose proportionality.
Evidence: Maximum serum concentrations reported: 52.5 μg/mL at 5 mg/kg, 104.8 at 10 mg/kg, 197.0 at 20 mg/kg, 417.1 at 30 mg/kg, 542.0 at 40 mg/kg.
“L9LS showed dose-proportional pharmacokinetics in this trial, with maximum serum concentrations of 52.5 μg/mL at 5 mg/kg, 104.8 μg/mL at 10 mg/kg, 197.0 μg/mL at 20 m/kg, 417.1 μg/mL at 30 mg/kg, and 542.0 μg/mL at 40 mg/kg.”
supportedAbstract, Results, Discussion
L9LS is safe and well tolerated in children aged 5 months to 10 years.
Supported by the presented safety data: similar rates of adverse events between L9LS and placebo groups, no related serious adverse events, and all grade 3 events resolved.
Evidence: Results sections on safety, Table 2, and supplementary tables show low rates of solicited events and no dose-related trends.
“L9LS was protective against malaria in young children in western Kenya without evident safety concerns over 6–12 months.”
supportedAbstract, Results
Two doses of L9LS (10-20 mg/kg) provide 43% efficacy against P. falciparum infection over 12 months.
Supported by the primary endpoint analysis: hazard ratio from Cox model with p=0.0003 and 95% CI 22.5-57.7.
Evidence: Results, paragraph 1 and Figure 2.
“In part 2, 70 (66%) of 106 children in the two-dose L9LS group had at least one P falciparum infection during the 12-month follow-up versus 91 (83%) of 110 children in the placebo group (protective efficacy 42.7%, 95% CI 22.5–57.7; p=0.0003).”
supportedAbstract, Results
One dose of L9LS provides 46% efficacy against infection over 6 months.
Supported by the 6-month analysis combining both L9LS groups vs placebo.
Evidence: Results, paragraph 2: 'At 6 months... protective efficacy 45.9% [95% CI 26.5–60.1]; p=0.0001'.
“At 6 months, after one dose of L9LS (both L9LS groups) or placebo, infections occurred in 99 (46%) of 214 children in the L9LS group and 71 (65%) of 110 in the placebo group (protective efficacy 45.9% [95% CI 26.5–60.1]; p=0.0001)”
supportedResults, paragraph 4
L9LS did not elicit antidrug antibodies.
Supported by the reported assay results: no antidrug antibodies detected in L9LS groups at any timepoint.
Evidence: Results, paragraph on antidrug antibodies: 'No antidrug antibodies were detected among children in the L9LS groups at any timepoints in parts 1a and 1b or in part 2'.
“No antidrug antibodies were detected among children in the L9LS groups at any timepoints in parts 1a and 1b or in part 2”
supportedResults, efficacy
Two doses of L9LS at 10-20 mg/kg provide 43% efficacy against P. falciparum infection and 48% against clinical malaria over 12 months.
Primary analysis and secondary analysis clearly show statistically significant protection with reported effect sizes and CIs.
Evidence: Protective efficacy 42.7% (95% CI 22.5-57.7) against infection; 48.3% (95% CI 27.4-63.1) against clinical malaria.
“the protective efficacy of two doses of L9LS against P falciparum infection by blood smear at 12 months... was 42·7% (95% CI 22·5–57·7; p=0·0003)... Protective efficacy of two doses of L9LS against clinical malaria... at 12 months was 48·3% (95% CI 27·4–63·1)”

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

Rigor

Eight Dimensions7 pass · 1 warn

12 major claims3 partial9 supported

9 copyedit issues flagged: mostly typo, consistency, other.

Checked 30 references: 2 verified — 28 unresolved.

Reproducibility

Registered (6 IDs: ClinicalTrials.gov). No reporting guideline cited.

Alpha¹ Rigor Action ItemsFinal pass before journal submission

Post-publication robustness assessment: The paper is generally robust but has notable reporting gaps. An informed reader should weigh that the trial has not yet deposited data in a public repository, the ethical statement lacks an explicit reference to the Declaration of Helsinki or ICH-GCP, and many references were not found in any registry. These issues do not invalidate the primary findings but would warrant a correction or erratum to address data availability, ethical compliance statement, and citation verification.

1.
HIGHdata code
Deposit anonymized data in a named public repository (e.g., ClinicalStudyDataRequest or Vivli) and provide a persistent identifier in the data availability statement to replace the current vague plan.
The current statement promises future deposit with no repository name or DOI, which is inadequate for a published paper and undermines reproducibility.
2.
HIGHethics
Add an explicit statement that the trial was conducted in accordance with the Declaration of Helsinki and/or ICH-GCP guidelines to the ethics section.
The absence of an explicit international ethical framework statement is a standard reporting gap that could be raised by readers or journals.
3.
HIGHreporting
Verify the 12 references that were not found in any registry (World malaria report 2025, Genetic surveillance of insecticide resistance in African Anopheles populations to inform malaria vector control, Artemisinin-resistant malaria, Monoclonal antibodies to the circumsporozoite proteins as an emerging tool for malaria prevention, Malaria prevention: from immunological concepts to effective vaccines and protective antibodies, Monoclonal antibodies for malaria, Safety and efficacy of a monoclonal antibody against malaria in Mali, Subcutaneous administration of a monoclonal antibody to prevent malaria, Post-discharge morbidity and mortality in children admitted with severe anaemia and other health conditions in malaria-endemic settings in Africa: a systematic review and meta-analysis, A monoclonal antibody for malaria prevention, A candidate antibody drug for prevention of malaria, Low-dose subcutaneous or intravenous monoclonal antibody to prevent malaria) and correct or replace them; these may be fabricated or incorrectly cited.
References not found in any registry raise integrity concerns; accurate citations are essential for scholarly trust.
4.
MEDIUMreporting
Reference the CONSORT 2010 checklist and provide a completed checklist as supplementary material, or state adherence in the Methods.
Explicit reporting guideline adherence is expected for clinical trials and facilitates completeness assessment.
5.
MEDIUMreporting
Report race/ethnicity of participants or provide a justification for its omission in the baseline characteristics table.
Though not mandatory, race/ethnicity is a standard demographic variable in clinical trials; its absence may be questioned.
6.
MEDIUMcopyedit
Fix typographical errors: 'chidren' -> 'children' in Figure 1 footnote; '20 m/kg' -> '20 mg/kg' in Results (Pharmacokinetics); '5–17-months' -> '5–17 months' in Table 1 note; and use consistent decimal formatting (period vs. middle dot) for pharmacokinetic values.
These minor errors detract from manuscript polish and could be misinterpreted.
7.
LOWstatistics
Provide a brief verification of the proportional hazards assumption for the Cox models (e.g., test based on Schoenfeld residuals) in the statistical analysis section.
Although the Cox model is standard, formally testing the assumption strengthens the analysis and is a common reviewer request.
8.
LOWdata code
Share the analysis code (R scripts) in a public repository with a DOI to enhance reproducibility.
Even if standard packages were used, sharing code allows full reproducibility and is increasingly expected.
9.
LOWreporting
Include the lot number of L9LS in the Procedures section for complete reagent identification.
Providing a lot number facilitates traceability of the investigational product.
10.
LOWcopyedit
Use consistent terminology: 'modified intent-to-treat' (mITT) throughout instead of alternating with 'intention-to-treat'.
Consistent terminology improves clarity and avoids confusion.

Full text (60,055 chars)Analyzed: Jul 5, 2026

Αlpha¹ assesses methodological rigor, not the importance of the findings. See how we calibrate →