Natural and cryptic peptides dominate the immunopeptidome of atypical teratoid rhabdoid tumors.

Atypical teratoid/rhabdoid tumors (AT/RT) are highly aggressive CNS-tumors of infancy and early childhood. Hallmark is the surprisingly simple genomics with a truncating mutation in the SMARCB1 gene as the oncogenic driver. Nevertheless, AT/RTs are infiltrated by immune cells and even clonally expanded T-cells. However, it is unclear, what T-cells might recognize on AT/RT cells. Here, we report a comprehensive analysis of naturally presented HLA-class-I and class-II ligands on n=23 AT/RTs. MS-based analysis of the HLA-ligandome revealed 55 class-I and 139 class-II peptides from tumor-associated proteins.