{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T23:23:18Z","timestamp":1785367398246,"version":"3.55.0"},"reference-count":9,"publisher":"SAGE Publications","issue":"7","license":[{"start":{"date-parts":[[2025,6,1]],"date-time":"2025-06-01T00:00:00Z","timestamp":1748736000000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"},{"start":{"date-parts":[[2025,6,1]],"date-time":"2025-06-01T00:00:00Z","timestamp":1748736000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["Mult Scler"],"published-print":{"date-parts":[[2025,6]]},"abstract":"\n Background:<\/jats:title>\n A 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.<\/jats:p>\n <\/jats:sec>\n \n Methods:<\/jats:title>\n A total of 497 people with MS, who had switched from Tysabri to Tyruko with sequential results available on both assays, were included.<\/jats:p>\n <\/jats:sec>\n \n Results:<\/jats:title>\n Of 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.<\/jats:p>\n <\/jats:sec>\n \n Conclusion:<\/jats:title>\n These 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.<\/jats:p>\n <\/jats:sec>","DOI":"10.1177\/13524585251346652","type":"journal-article","created":{"date-parts":[[2025,6,14]],"date-time":"2025-06-14T08:30:47Z","timestamp":1749889847000},"page":"882-885","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":8,"title":["A comparison of JC virus assay performance provided with originator and biosimilar natalizumab"],"prefix":"10.1177","volume":"31","author":[{"ORCID":"https:\/\/orcid.org\/0009-0009-8338-8859","authenticated-orcid":false,"given":"James","family":"Varley","sequence":"first","affiliation":[{"name":"Department of Neurology, Imperial College Healthcare NHS Trust, London, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rahma","family":"Beyrouti","sequence":"additional","affiliation":[{"name":"Queen Square Multiple Sclerosis Centre, Department of Neuroinflammation, UCL Institute of Neurology, London, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Richard","family":"Nicholas","sequence":"additional","affiliation":[{"name":"Department of Neurology, Imperial College Healthcare NHS Trust, London, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rachel","family":"Dorsey","sequence":"additional","affiliation":[{"name":"Department of Neurology, Imperial College Healthcare NHS Trust, London, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wallace","family":"Brownlee","sequence":"additional","affiliation":[{"name":"Queen Square Multiple Sclerosis Centre, Department of Neuroinflammation, UCL Institute of Neurology, London, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David","family":"Paling","sequence":"additional","affiliation":[{"name":"Academic Department of Neuroscience, Sheffield NIHR Neuroscience BRC, Sheffield Teaching Hospital NHS Foundation Trust, Sheffield, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joela","family":"Mathews","sequence":"additional","affiliation":[{"name":"Department of Neurology, Royal London Hospital, Barts Health NHS Trust, London, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2993-585X","authenticated-orcid":false,"given":"Ruth","family":"Dobson","sequence":"additional","affiliation":[{"name":"Department of Neurology, Royal London Hospital, Barts Health NHS Trust, London, UK"},{"name":"Centre for Preventive Neurology, Wolfson Institute of Population Health, Queen Mary University of London, London, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"179","published-online":{"date-parts":[[2025,6,14]]},"reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa044397"},{"key":"e_1_3_2_3_2","first-page":"117","article-title":"Stratification and monitoring of natalizumab-associated progressive multifocal leukoencephalopathy risk: Recommendations from an expert group","volume":"87","author":"McGuigan C","year":"2016","unstructured":"McGuigan C, Craner M, Guadagno J, et al. Stratification and monitoring of natalizumab-associated progressive multifocal leukoencephalopathy risk: Recommendations from an expert group. J Neurol Neurosurg Psychiat 2016; 87: 117\u2013125","journal-title":"J Neurol Neurosurg Psychiat"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0174005"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.3389\/fimmu.2018.02435"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.msard.2022.104251"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.1177\/1756286421998915"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1001\/jamaneurol.2022.5007"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1177\/13524585241300972"},{"key":"e_1_3_2_10_2","unstructured":"TYSABRI 300 mg concentrate for solution for infusion \u2013 Summary of Product Characteristics (SmPC) \u2013 (emc) https:\/\/www.medicines.org.uk\/emc\/product\/222\/smpc"}],"container-title":["Multiple Sclerosis Journal"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/13524585251346652","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/full-xml\/10.1177\/13524585251346652","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/13524585251346652","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,2]],"date-time":"2026-05-02T04:18:44Z","timestamp":1777695524000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/10.1177\/13524585251346652"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,6]]},"references-count":9,"journal-issue":{"issue":"7","published-print":{"date-parts":[[2025,6]]}},"alternative-id":["10.1177\/13524585251346652"],"URL":"https:\/\/doi.org\/10.1177\/13524585251346652","relation":{},"ISSN":["1352-4585","1477-0970"],"issn-type":[{"value":"1352-4585","type":"print"},{"value":"1477-0970","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,6]]}}}