Antitumor Activity of a Monoclonal Antibody Targeting Major Histocompatibility Complex Class I-Her2 Peptide Complexes

• Published in: JNCI : Journal of the National Cancer Institute Vol. 105; no. 3; pp. 202 - 218
• Main Authors: JAIN, Rinki, RAWAT, Amit, VERMA, Bhavna, MARKIEWSKI, Maciej M, WEIDANZ, Jon A
• Format: Journal Article
• Language: English
• Published: Cary, NC Oxford University Press 06.02.2013; Oxford Publishing Limited (England)
• Subjects: Animal tumors. Experimental tumors; Animals; Antibodies, Monoclonal - pharmacology; Antibodies, Monoclonal, Humanized - pharmacology; Antineoplastic agents; Antineoplastic Agents - pharmacology; Apoptosis - drug effects; Biological and medical sciences; Breast cancer; Breast Neoplasms - drug therapy; Carcinoma - drug therapy; Caspase 3 - metabolism; Cell Line, Tumor; Cell Survival - drug effects; Colorectal Neoplasms - drug therapy; Enzyme-Linked Immunosorbent Assay; Experimental tumors, general aspects; Female; Flow Cytometry; Frozen Sections; Gene Expression Regulation, Neoplastic - drug effects; HLA-A2 Antigen - drug effects; HLA-A2 Antigen - metabolism; Humans; Immunohistochemistry; Immunosorbent Techniques; Immunotherapy; Intracellular Signaling Peptides and Proteins - drug effects; Intracellular Signaling Peptides and Proteins - metabolism; Medical sciences; Mice; Mice, Nude; Microscopy, Confocal; Microscopy, Fluorescence; Nanoparticles; Neoplasms - drug therapy; Neoplasms - metabolism; Oncogene Proteins, Fusion - antagonists & inhibitors; Oncogene Proteins, Fusion - metabolism; Oncology; Pancreatic Neoplasms - drug therapy; Peptide Fragments - drug effects; Peptide Fragments - metabolism; Peptides; Pharmacology. Drug treatments; Poly(ADP-ribose) Polymerases - metabolism; Receptor, ErbB-2 - antagonists & inhibitors; Receptor, ErbB-2 - metabolism; Receptors, Antigen, T-Cell - agonists; Signal Transduction - drug effects; T cell receptors; Trastuzumab; Tumors; Up-Regulation; Womens health; Xenograft Model Antitumor Assays; Antineoplastic agent; Human; HLA-System; Peptides; Targeted therapy; Major histocompatibility system; Rodentia; erbB2 Gene; Monoclonal antibody; Malignant tumor; Complexes; Human Epidermal growth factor Receptor 2; Vertebrata; Mammalia; Cancerology; Treatment; Mouse; Animal; C-Onc gene; Immunotherapy; Genetics; Class I histocompatibility antigen; Protooncogene; Cancer
• ISSN: 0027-8874; 1460-2105
• DOI: 10.1093/jnci/djs521

Applications of trastuzumab are limited to breast cancer patients with high Her2-expressing tumors. We developed a T-cell receptor mimic (TCRm) monoclonal antibody (hereafter called RL1B) that targets the Her2-E75 peptide (residues 369-377)-HLA-A2 complex and examined its effects in Her2-expressing cancer cells. RL1B binding affinity was determined by surface plasmon resonance and specificity was demonstrated using Her2 antigen-positive and negative tumor cell lines. Immunohistochemistry was used to assess binding to frozen sections of human carcinomas (n = 3). Antitumor activity mediated by RL1B and trastuzumab against Her2(+) tumor cell lines was evaluated using the WST-1 cell viability assay and caspase-3 and poly(ADP-ribose) polymerase cleavage assays. A xenograft mouse model (n = 6 per group) was used to assess RL1B antitumor activity. Mechanisms of RL1B-mediated cytotoxicity were evaluated with confocal microscopy, flow cytometry, and histology. All statistical tests were two-sided. RL1B bound with high specificity and affinity to the E75 peptide-HLA-A2 complex in all Her2(+) and HLA-A2(+) cancer cell lines and human carcinomas. Compared with control antibody, RL1B suppressed growth of low Her2-expressing breast tumors in mice (mean volume, RL1B vs control = 241 mm(3) vs 1531 mm(3); P = .0109) and statistically significantly increased mouse survival (P = .0098). It reduced viability compared to control monoclonal antibody-treated cells and statistically significantly increased caspase 3 activation of all Her2(+) carcinoma cell lines tested, whereas trastuzumab induced apoptosis only in high Her2-expressing cancer cells. Mechanisms of RL1B cytotoxicity were associated with antibody internalization and intracellular signaling. The TCRm RL1B could be a new approach to immunotherapy of Her2-expressing malignancies.