biostudies-literatureUnknownMohn N<h4>Importance</h4>Progressive multifocal leukoencephalopathy (PML) is a life-threatening demyelinating disease caused by reactivation of the JC virus (JCV) in immunocompromised patients. While immune checkpoint inhibitors (ICIs) show therapeutic potential, responses vary and predictive biomarkers are lacking.<h4>Objective</h4>To determine whether pretreatment JCV- and/or BK virus-specific T cells in the blood are associated with treatment efficacy.<h4>Design, setting, and participants</h4>This retrospective cohort study included 111 patients with PML who were treated with ICIs stratified by peripheral virus-specific T cell presence (ELISpot/flow cytometry) between August 2021 and May 2024, with a median (IQR) follow-up of 7 (1-13) months. Of 112 patients with definite PML across 39 centerJAMA neurologyhttps://www.ebi.ac.uk/biostudies/studies/S-EPMC12820779biostudies-literatureVirus-Specific T Cells and Response to Checkpoint Inhibitors in Progressive Multifocal Leukoencephalopathy.PMC12820779Wicklein RJelcic IDel Bello AJendretzky KFCortese ICiron JHuhnchen PWarnke CBerger JSommet AMeuth SGKonen FFGourdon FKupper CDelobel PPignolet BGnanapavan SOuallet JCLeveneur YTumani HDinur-Schejter YBernard-Valnet RRauer SGrimbacher BGrassl NAntinori ABruggemann NDucours MGoreci YRoos-Weil DNey DImmunotherapy for PML Study GroupKaracondi KSuhs KWTischer-Zimmermann SSchneider RZent MMaecker-Kolhoff BGrote-Levi LPourcher VBonifacius ASassmann MLGasnault JKamar NEiz-Vesper BKapadia RAouba ABeudel MZahraeifard SPerpoint TWijburg MLambert NLe Marechal MTreiner EBrousse XClifford DShamriz OGaudin MNitsch LCimini EMartin-Blondel GBiotti DRibaute CShifman TManda VPawlitzki MHoglinger GUAlt LKleinschnitz CBoltz SGrauer OLhomme SHarel ANay SWiendl HRakotoarison JRMohn NAyzenberg IKlebe SPinnetti CPul RCohen-Aubart FBonneau BHelmchen CJoly MBoumaza XHildner MBonneville FBrouwer MWeiss NEngalenc XDe Menibus LLifermann FSkripuletz TMrabet HGrefkes CLajaunie RLambotte ODuffau PWyplosz BfalseVirus-Specific T Cells and Response to Checkpoint Inhibitors in Progressive Multifocal Leukoencephalopathy.<h4>Importance</h4>Progressive multifocal leukoencephalopathy (PML) is a life-threatening demyelinating disease caused by reactivation of the JC virus (JCV) in immunocompromised patients. While immune checkpoint inhibitors (ICIs) show therapeutic potential, responses vary and predictive biomarkers are lacking.<h4>Objective</h4>To determine whether pretreatment JCV- and/or BK virus-specific T cells in the blood are associated with treatment efficacy.<h4>Design, setting, and participants</h4>This retrospective cohort study included 111 patients with PML who were treated with ICIs stratified by peripheral virus-specific T cell presence (ELISpot/flow cytometry) between August 2021 and May 2024, with a median (IQR) follow-up of 7 (1-13) months. Of 112 patients with definite PML across 39 center2026-01-01T00:00:00Z2026 Jan2026-06-06T19:28:49.197Z2026-06-04T03:10:43.772ZS-EPMC128207794155734010.1001/jamaneurol.2025.5318