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.
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
Angelos D
AD
Gritzapis
Ioannis F
IF
Voutsas
Eftychia
E
Lekka
Nikolaos
N
Tsavaris
Ioannis
I
Missitzis
Panagiota
P
Sotiropoulou
Sonia
S
Perez
Michael
M
Papamichail
Constantin N
CN
Baxevanis
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