Modification of the HER2/NEU-derived tumor antigen GP2 improves induction of GP2-reactive cytotoxic T lymphocytes.
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/neu-overexpressing tumor cells was measured in (51)Cr release and IFN-gamma 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.
Tanaka
Y
Y
Washington University School of Medicine, Department of Surgery, Biologic Cancer Therapy Program, St. Louis, MO 63110, USA.
Amos
K D
KD
Joo
H G
HG
Eberlein
T J
TJ
Goedegebuure
P S
PS
D000596:Amino Acids / Q000737:chemistry; D000951:Antigens, Neoplasm / Q000737:chemistry*; D002460:Cell Line; D003713:Dendritic Cells / Q000378:metabolism; D006680:HLA Antigens / Q000276:immunology; D015234:HLA-A Antigens / Q000276:immunology; D015789:HLA-A2 Antigen; D006801:Humans; D010446:Peptide Fragments / Q000737:chemistry* / Q000627:therapeutic use*; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000737:chemistry* / Q000276:immunology* / Q000627:therapeutic use*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured
D000596:Amino Acids; D000951:Antigens, Neoplasm; D006680:HLA Antigens; D015234:HLA-A Antigens; D015789:HLA-A2 Antigen; D010446:Peptide Fragments; D010455:Peptides; D018719:Erb-b2 Receptor Tyrosine Kinases; C091577:HER2-neu-derived peptide (654-662); C435939:HLA-A*02:01 antigen