Family with sequence similarity 53 member B cryptic peptide (FAM53B-219aa) (FAM53B-219aa)

The FAM53B-219aa cryptic peptide is a non-canonical translation product derived from a circular RNA transcript of the FAM53B gene (circFAM53B). Unlike the canonical FAM53B protein, this 219-amino-acid peptide is specifically overexpressed in various malignant tissues, particularly in breast cancer and melanoma, while remaining largely absent in healthy tissues. It functions as a potent tumor-specific antigen that is presented on the cell surface by HLA class I (notably HLA-A*02:01) and class II molecules. By serving as an immunogenic epitope, the peptide can prime and activate both CD4+ and CD8+ T cells to mount a targeted antitumor immune response. Therapeutically, the FAM53B-219aa peptide is being utilized as a target for personalized cancer vaccines, including dendritic cell-based vaccines and mRNA-based formulations. These treatments aim to enhance the infiltration of antigen-specific cytotoxic T lymphocytes into the tumor microenvironment to inhibit tumor growth. Clinical investigations often combine these vaccines with immune checkpoint inhibitors, such as PD-1 antibodies, to overcome immunosuppression and improve therapeutic efficacy in patients with advanced solid tumors. The target represents a novel class of "dark matter" antigens that expand the landscape of precision immunotherapy beyond traditional mutated neoantigens.

Other names

CircFAM53B-219aacircFAM53B-encoded 219aa peptideKIAA0140 cryptic peptideFAM53B-219aa

The target serves as a tumor-specific antigen (TSA) which, when delivered via vaccine, is presented by HLA-A*02:01 and HLA-II molecules to activate a specific cytotoxic T-lymphocyte (CTL) response and CD4+ T cell help against tumor cells expressing the peptide.