Identification of a novel immunogenic HLA-A*0201-binding epitope of HER-2/neu with potent antitumor properties.
HER-2/neu oncoprotein is overexpressed in a variety of human tumors and is associated with aggressive disease. Immunogenic HER-2/neu CTL epitopes have been used as vaccines for the treatment of HER-2/neu positive malignancies with limited success. By applying prediction algorithms for MHC class I ligands and proteosomal cleavages, in this study, we describe the identification of HER-2/neu decamer LIAHNQVRQV spanning residues 85-94 (HER-2(10(85))). HER-2(10(85)) proved to bind with high affinity to HLA-A2.1 and was stable for 4 h in an off-kinetics assay. This peptide was immunogenic in HLA-A2.1 transgenic (HHD) mice inducing peptide-specific CTL, which responded to tumor cell lines of various origin coexpressing human HER-2/neu and HLA-A2.1. This demonstrates that HER-2(10(85)) is naturally processed from endogenous HER-2/neu. Five of sixteen HER-2/neu+ HLA-A2.1+ breast cancer patients analyzed had HER-2(10(85))-reactive T cells ranging from 0.35-0.70% of CD8+ T cells. Depletion of T regulatory cells from PBMC enabled the rapid expansion of HLA-A2.1/HER-2(10(85))pentamer+/CD8+ cells (PENT+/CD8+), whereas significantly lower numbers of CTL could be generated from unfractionated PBMC. HER-2(10(85))-specific human CTL recognized the HER-2/neu+ HLA-A2.1+ tumor cell line SKBR3.A2, as determined by IFN-gamma intracellular staining and in the high sensitivity CD107alpha degranulation assay. Finally, HER-2(10(85)) significantly prolonged the survival of HHD mice inoculated with the transplantable ALC.A2.1.HER tumor both in prophylactic and therapeutic settings. These data demonstrate that HER-2(10(85)) is an immunogenic peptide, capable of eliciting CD8-mediated responses in vitro and in vivo, providing the platform for further exploitation of HER-2(10(85)) as a possible target for anticancer immunotherapy.
Gritzapis
Angelos D
AD
Cancer Immunology and Immunotherapy Center, Breast Cancer Clinic, St. Savas Cancer Hospital, and Pathophysiology Department, Medical School, National and Kapodistrian University of Athens, Athens, Greece. adgritzapis@ciic.gr
Voutsas
Ioannis F
IF
Lekka
Eftychia
E
Tsavaris
Nikolaos
N
Missitzis
Ioannis
I
Sotiropoulou
Panagiota
P
Perez
Sonia
S
Papamichail
Michael
M
Baxevanis
Constantin N
CN
D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D019496:Cancer Vaccines / Q000276:immunology; D045744:Cell Line, Tumor; D018450:Disease Progression; D000939:Epitopes / Q000276:immunology*; D015234:HLA-A Antigens / Q000276:immunology*; D015789:HLA-A2 Antigen; D006801:Humans; D051379:Mice; D011485:Protein Binding; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D023041:Xenograft Model Antitumor Assays
D019496:Cancer Vaccines; D000939:Epitopes; D015234:HLA-A Antigens; D015789:HLA-A2 Antigen; D018719:Erb-b2 Receptor Tyrosine Kinases; C435939:HLA-A*02:01 antigen