EWS-FLI1 fusion protein-derived peptide antigens (EWS-FLI1 peptide antigens)

EWS-FLI1 fusion protein-derived peptide antigens are tumor-specific neoantigens generated by the pathognomonic t(11;22)(q24;q12) chromosomal translocation found in approximately 85-90% of Ewing sarcoma cases (NIH, 2025; MDPI, 2021). This translocation fuses the N-terminal transactivation domain of the EWSR1 gene with the C-terminal DNA-binding domain of the FLI1 gene, resulting in a chimeric transcription factor that drives oncogenesis (NIH, 2015). The unique amino acid sequence at the fusion breakpoint serves as a highly specific target for immunotherapy, as it is entirely absent from the normal human proteome (ResearchGate, 2017). These peptides are processed and presented on the surface of tumor cells by Major Histocompatibility Complex (MHC) molecules, where they can be recognized by the T-cell receptor (TCR) of cytotoxic T-lymphocytes (AACR, 2012). Therapeutic approaches targeting these antigens include peptide vaccines, dendritic cell vaccines, and adoptive T-cell therapies, such as TCR-engineered T cells (AACR, 2021). A significant challenge in targeting these antigens is the low binding affinity of native junctional peptides to common HLA alleles, which has led to the development of modified anchor-fixed or heteroclitic peptides with improved MHC stability and immunogenicity (AACR, 2012).

Other names

EWS-FLI1 neoantigensEWS-FLI1 junction peptidesEWS-FLI1 fusion region peptidesEWS-FLI1 breakpoint peptidesEWS-FLI1 epitopes

Induction of a tumor-specific cytotoxic T-lymphocyte (CTL) response by targeting unique amino acid sequences at the EWS-FLI1 fusion junction presented on MHC molecules (AACR, 2012; ResearchGate, 2017).