Endogenous H3.3K27M derived peptide restricted to HLA-A∗02:01 is insufficient for immune-targeting in diffuse midline glioma

Stacie S. Wang, Kirti Pandey, Katherine A. Watson, Rebecca C. Abbott, Nicole A. Mifsud, Fiona M. Gracey, Sri H. Ramarathinam, Ryan S. Cross, Anthony W. Purcell, Misty R. Jenkins

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3 Citations (Scopus)


Diffuse midline glioma (DMG) is a childhood brain tumor with an extremely poor prognosis. Chimeric antigen receptor (CAR) T cell therapy has recently demonstrated some success in DMG, but there may a need to target multiple tumor-specific targets to avoid antigen escape. We developed a second-generation CAR targeting an HLA-A∗02:01 restricted histone 3K27M epitope in DMG, the target of previous peptide vaccination and T cell receptor-mimics. These CAR T cells demonstrated specific, titratable, binding to cells pulsed with the H3.3K27M peptide. However, we were unable to observe scFv binding, CAR T cell activation, or cytotoxic function against H3.3K27M+ patient-derived models. Despite using sensitive immunopeptidomics, we could not detect the H3.3K27M26–35-HLA-A∗02:01 peptide on these patient-derived models. Interestingly, other non-mutated peptides from DMG were detected bound to HLA-A∗02:01 and other class I molecules, including a novel HLA-A3-restricted peptide encompassing the K27M mutation and overlapping with the H3 K27M26–35-HLA-A∗02:01 peptide. These results suggest that targeting the H3 K27M26–35 mutation in context of HLA-A∗02:01 may not be a feasible immunotherapy strategy because of its lack of presentation. These findings should inform future investigations and clinical trials in DMG.

Original languageEnglish
Pages (from-to)167-180
Number of pages14
JournalMolecular Therapy - Oncolytics
Publication statusPublished - 21 Sept 2023


  • CAR T cells
  • DIPG
  • DMG
  • H3.3K27M
  • immunopeptidomics
  • immunotherapy
  • pediatric brain tumor
  • peptide-MHC
  • proteomics
  • T cell cytotoxicity

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