A case report of clonal EBV-like memory CD4 T cell activation in fatal checkpoint inhibitor-induced encephalitis.

Johnson DB, McDonnell WJ, Gonzalez-Ericsson PI, Al-Rohil RN, Mobley BC, Salem JE, Wang DY, Sanchez V, Wang Y, Chastain CA, Barker K, Liang Y, Warren S, Beechem JM, Menzies AM, Tio M, Long GV, Cohen JV, Guidon AC, O'Hare M, Chandra S, Chowdhary A, Lebrun-Vignes B, Goldinger SM, Rushing EJ, Buchbinder EI, Mallal SA, Shi C, Xu Y, Moslehi JJ, Sanders ME, Sosman JA, Balko JM
Nat Med. 2019 25 (8): 1243-1250

PMID: 31332390 · PMCID: PMC6689251 · DOI:10.1038/s41591-019-0523-2

Checkpoint inhibitors produce durable responses in numerous metastatic cancers, but immune-related adverse events (irAEs) complicate and limit their benefit. IrAEs can affect organ systems idiosyncratically; presentations range from mild and self-limited to fulminant and fatal. The molecular mechanisms underlying irAEs are poorly understood. Here, we report a fatal case of encephalitis arising during anti-programmed cell death receptor 1 therapy in a patient with metastatic melanoma. Histologic analyses revealed robust T cell infiltration and prominent programmed death ligand 1 expression. We identified 209 reported cases in global pharmacovigilance databases (across multiple cancer types) of encephalitis associated with checkpoint inhibitor regimens, with a 19% fatality rate. We performed further analyses from the index case and two additional cases to shed light on this recurrent and fulminant irAE. Spatial and multi-omic analyses pinpointed activated memory CD4 T cells as highly enriched in the inflamed, affected region. We identified a highly oligoclonal T cell receptor repertoire, which we localized to activated memory cytotoxic (CD45ROGZMBKi67) CD4 cells. We also identified Epstein-Barr virus-specific T cell receptors and EBV lymphocytes in the affected region, which we speculate contributed to neural inflammation in the index case. Collectively, the three cases studied here identify CD4 and CD8 T cells as culprits of checkpoint inhibitor-associated immune encephalitis.

MeSH Terms (15)

Adolescent Adult Aged Aged, 80 and over CD4-Positive T-Lymphocytes Encephalitis Female Herpesvirus 4, Human Humans Immunologic Memory Lymphocyte Activation Male Middle Aged Programmed Cell Death 1 Receptor Young Adult

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