Case Report: Severe HHV-6-related encephalitis following anti-CD19 CAR-T therapy with no evidence of HHV-6 reactivation in transduced CAR-T cells

We report a case of severe encephalitis caused by human herpes virus 6 (HHV-6) following CD19 chimeric antigen receptor T (CAR-T) cell therapy. Rapid expansion of circulating T-lymphocytes and high HHV-6 viral load (4,500,000 DNA copies/mL) early after CAR-T infusion suggested HHV-6 transferal from autologous CAR-T cells. To investigate this hypothesis, we retrospectively analyzed cryo-preserved patient samples for HHV-6. HHV-6 was undetectable in the apheresis product, transduced CAR-T cells, and in vitro activated CAR-T cells. In conclusion, despite strong clinical suspicion, we found no evidence to substantiate the infused CAR-T cells as the source of the severe HHV-6 infection.

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Publication Details

Journal
Frontiers in Hematology
Published
2025-09-19
DOI
https://doi.org/10.3389/frhem.2025.1628552
Primary Topic
CAR-T cell therapy research
Type
article
Field-Weighted Citation Impact
0.00

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article

Case Report: Severe HHV-6-related encephalitis following anti-CD19 CAR-T therapy with no evidence of HHV-6 reactivation in transduced CAR-T cells

Eva Haastrup, Thomas Morgan Hulen, Katrine Kielsen, Torben Barington et al.
Frontiers in Hematology
CAR-T cell therapy research
article

Case Report: Severe HHV-6-related encephalitis following anti-CD19 CAR-T therapy with no evidence of HHV-6 reactivation in transduced CAR-T cells

Eva Haastrup, Thomas Morgan Hulen, Katrine Kielsen, Torben Barington, Kristian Schønning, Jonas Vestergaard Nielsen, Marianne Ifversen, Charlotte Madsen, Özcan Met, Søren Lykke Petersen, Nina Marie Birk
article en

Abstract

We report a case of severe encephalitis caused by human herpes virus 6 (HHV-6) following CD19 chimeric antigen receptor T (CAR-T) cell therapy. Rapid expansion of circulating T-lymphocytes and high HHV-6 viral load (4,500,000 DNA copies/mL) early after CAR-T infusion suggested HHV-6 transferal from autologous CAR-T cells. To investigate this hypothesis, we retrospectively analyzed cryo-preserved patient samples for HHV-6. HHV-6 was undetectable in the apheresis product, transduced CAR-T cells, and in vitro activated CAR-T cells. In conclusion, despite strong clinical suspicion, we found no evidence to substantiate the infused CAR-T cells as the source of the severe HHV-6 infection.

Frontiers in HematologyVol. 4
University of Copenhagen (DK), University of Southern Denmark (DK), Odense University Hospital (DK), Herlev Hospital (DK), Copenhagen University Hospital (DK), Rigshospitalet (DK), IT University of Copenhagen (DK), Technical University of Denmark (DK)
Børnecancerfonden, Novo Nordisk, Faculty of Health and Medical Sciences, University of Western Australia, Novo Nordisk Fonden, Det Sundhedsvidenskabelige Fakultet, Københavns Universitet
Openalex Percentile: Top 65%
CAR-T cell therapy research
DOIOpen Access PDFOpenAlex
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