HLA-A*02:01-restricted Folate Binding Protein peptide E39 (HLA-A2/E39)

The HLA-A2–restricted presentation of the E39 peptide (sequence EIWTHSYKV) is a specific immunological target derived from Folate Binding Protein (FBP), also known as Folate Receptor alpha (FOLR1) [PMID: 10491017]. FBP is a glycosylphosphatidylinositol-anchored protein that is significantly overexpressed in over 90% of ovarian cancers and other epithelial malignancies, while maintaining limited expression in normal tissues, making it an ideal target for immunotherapy [PMID: 15930355]. The E39 peptide is an HLA-A*02:01-restricted epitope that is naturally processed and presented on the surface of tumor cells by Major Histocompatibility Complex (MHC) class I molecules [PMID: 23838931]. When administered as a vaccine, typically with an adjuvant like GM-CSF, E39 stimulates the expansion of FBP-specific CD8+ cytotoxic T lymphocytes (CTLs) that can recognize and lyse FBP-expressing cancer cells [PMID: 28433495]. Clinical trials have demonstrated that the E39 vaccine is safe and can induce long-term immune memory, potentially reducing recurrence rates in patients with high-risk ovarian and endometrial cancers [ClinicalTrials.gov: NCT01580696]. This target represents a personalized approach to cancer vaccination specifically for HLA-A2 positive patients.

Other names

E39 peptideFBP(191–199)Folate binding protein peptide E39EIWTHSYKV peptideHLA-A2/FBP complexFolate receptor alpha peptide E39

The E39 peptide vaccine acts as an active immunotherapy by providing a specific epitope for HLA-A*02:01 presentation, which activates and expands Folate Binding Protein-specific CD8+ cytotoxic T lymphocytes to target and eliminate tumor cells [PMID: 23838931].