Cross-immunizing potential of tumor MAGE-A epitopes recognized by HLA-A*02:01-restricted cytotoxic T lymphocytes

Almost all melanoma cells express at least one member of theMAGE-A antigen family, making the cytotoxic T cells (CTLs)epitopes with cross-immunizing potential in this family attractivecandidates for the broad spectrum of anti-melanomaimmunotherapy. In this study, four highly homologous peptides(P264: FLWGPRALA, P264I9: FLWGPRALI, P264V9:FLWGPRALV, and P264H8: FLWGPRAHA) from the MAGE-Aantigens were selected by homologous alignment. All fourpeptides showed high binding affinity and stability toHLA-A*02:01 molecules, and could prime CTL immune responsesin human PBMCs and in HLA-A*02:01/Kb transgenicmice. CTLs elicited by the four epitope peptides couldcross-lyse tumor cells expressing the mutual target antigens,except MAGE-A11 which was not tested. However, CTLs inducedby P264V9 and P264I9 showed the strongest target celllysis capabilities, suggesting both peptides may represent thecommon CTL epitopes shared by the eight MAGE-A antigens,which could induce more potent and broad-spectrum antitumorresponses in immunotherapy.