ArticleMultiple sclerosis (Houndmills, Basingstoke, England)2025
A comparison of JC virus assay performance provided with originator and biosimilar natalizumab.
Article in Multiple sclerosis (Houndmills, Basingstoke, England), 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
4 citing papers in PubMed.
- Threshold-Dependent Discordance Between STRATIFY JCV™ and IMMUNOWELL™ Assays in Relapsing Multiple Sclerosis.Neurology and therapy · 2026Article
- Inter-assay variability in anti-JC virus serology in the era of natalizumab biosimilars: implications for PML risk stratification.Frontiers in immunology · 2026Review
- Serum drug levels and JCV assay discrepancies after switching from originator to biosimilar natalizumab.BMJ neurology open · 2026Article
- Stratify and ImmunoWELL JCV tests performances in a real-world multiple sclerosis cohort: possible clinical implications of biosimilar Natalizumab use.Journal of neurology · 2025Article
Corrections and comments
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Authors and funding
8 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundA rare complication of natalizumab treatment is progressive multifocal leukoencephalopathy (PML); risk can be stratified using JC virus (JCV) antibody status. Risk calculators to aid clinical decision-making use cohort data tested using the Stratify-JCV assay. Following concerns of an increased number of JCV seropositive results following the switch to biosimilar natalizumab and the associated test switch, we sought to understand the clinical implications.
methodsA total of 497 people with MS, who had switched from Tysabri to Tyruko with sequential results available on both assays, were included.
resultsOf 250 patients negative on Stratify-JCV, 119 (47.6%) were subsequently positive on ImmunoWELL. Agreement was the poorest at lower JCV index, where positive/negative cutoffs inform risk stratification and pharmacovigilance protocols most significantly.
conclusionThese observed differences create uncertainty in how to counsel patients and best carry out PML surveillance. Specific concerns include overestimating risk leading to increased patient concern, increased monitoring burden and associated healthcare costs and lack of access to a highly effective therapy. It is incumbent on all stakeholders including pharmaceutical industry and test developers, patient groups, governmental authorities (including regulatory bodies) and clinicians to work together to find an expeditious solution.
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Registered trials
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