Modification of the HER2NEU‐derived tumor antigen GP2 improves induction of GP2‐reactive cytotoxic T lymphocytes

Abstract

GP2 (IISAVVGIL), the p654 -662 HER2/neu-derived tumor antigen, induces HLA-A2-restricted cytotoxic T lymphocytes (CTL) reactive to various epithelial cancers. The binding affinity of GP2 for HLA-A2, however, is very low. To improve the immunogenicity of GP2, we tested 10 different amino acid substitutions into GP2 at the C-and N-terminus. Five out of 10 modified peptides, especially those containing phenylalanine at position 1 (1F), showed a significantly improved binding affinity to HLA-A2. 1F-based modified peptides were well recognized by GP2-specific CTL. These peptides were used to stimulate peripheral blood lymphocytes from HLA-A2 healthy donors using peptide-pulsed autologous dendritic cells (DC). After 3 or more weekly stimulations, CTL activity against GP2 pulsed T2 (T2-GP2) and HER2/neuoverexpressing tumor cells was measured in 51 Cr release and IFN-␥ secretion assays. The modified peptides significantly enhanced GP2-specific CTL activity in some donors. In particular, the peptide with phenylalanine at position 1, leucine at position 2 and valine at position 10 (1F2L10V) maximized the CTL activity against both T2-GP2 and HER2/neu-positive tumor cells. Peptide 1F2L10V increased not only the binding affinity to HLA-A2 but also improved recognition of GP2. These data suggest that DC ؉ modified GP2 may improve immune therapies for the treatment of HER2/neu overexpressing tumors.

Enhanced anti-colon cancer immune responses with modified eEF2-derived peptides

“…These results are in accordance with several reports showing a relationship between MHC class I binding and in vivo and in vitro immunogenicity [35][36][37][38][39]. Tanaka et al [40] reported that modified peptides not only increased the binding affinity to HLA-A2 but also improved recognition of native peptide. However, it needs to be further investigated whether or not it can also promote the expansion or proliferation of Ag-specific CTL.…”

Identification of HLA‐A3‐restricted CD8+ T cell epitopes derived from mammaglobin‐A, a tumor‐associated antigen of human breast cancer

“…The discrepancies between the predicted affinity of the peptides and their corresponding membrane stabilization ability of the HLA-A3 molecule may be due to the fact that the binding affinity of the peptide is determined by both the binding motifs as well as the 3-dimentional structure of the peptide in the MHC Class I groove. 23,24 Because it has been shown previously that the affinity of a given peptide to a MHC class I molecule does not necessarily correlate with its ability to generate CD8ϩ CTLs, 25,26 we used all the peptides to examine the profile of CD8ϩ CTL reactivity in 5 HLA-A3ϩ breast cancer patients and 4 HLA-A3ϩ healthy female controls by means of an ELISPOT assay as described. As shown in Table V showed CD8ϩ CTL reactivity against peptides MamA-3.1 and Mam-A3.3 and 2 patients (40%) showed CD8ϩ CTL reactivity against peptide Mam-A3.8.…”

Structure-based prediction of MHC–peptide association: Algorithm comparison and application to cancer vaccine design

“…To place the binding score on an appropriate scale, the structures of a peptide known to be a strong HLA-A2 binder (GILGFVFTL; derived from the influenza matrix virus [35]) and a peptide known as a weak HLA-A2 binder (IISAVVGIL; the Gp2 peptide from HER2/Neu [12,13]) were predicted using PePSSI. Eqs.…”

“…For peptide vaccination, the antigenic peptide is derived from a protein that is overexpressed in the targeted tumor cells [11]; one of the best known examples of this is the Gp2 peptide fragment of the HER2/Neu protein, which is commonly overexpressed in breast cancer [12,13]. Therefore, prediction of whether a peptide will bind to a particular human MHC molecule is of importance for development of peptide-based vaccines [11], and computational approaches have been created to identify such peptides.…”