Identification of T-cell Receptors Targeting KRAS-Mutated Human Tumors

Abstract

KRAS is one of the most frequently mutated proto-oncogenes in human cancers. The dominant oncogenic mutations of KRAS are single amino acid substitutions at codon 12, in particular G12D and G12V present in 60% to 70% of pancreatic cancers and 20% to 30% of colorectal cancers. The consistency, frequency, and tumor specificity of these “neoantigens” make them attractive therapeutic targets. Recent data associate T cells that target mutated antigens with clinical immunotherapy responses in patients with metastatic melanoma, lung cancer, or cholangiocarcinoma. Using HLA-peptide prediction algorithms, we noted that HLA-A*11:01 could potentially present mutated KRAS variants. By immunizing HLA-A*11:01 transgenic mice, we generated murine T cells and subsequently isolated T-cell receptors (TCR) highly reactive to the mutated KRAS variants G12V and G12D. Peripheral blood lymphocytes (PBL) transduced with these TCRs could recognize multiple HLA-A*11:01⁺ tumor lines bearing the appropriate KRAS mutations. In a xenograft model of large established tumor, adoptive transfer of these transduced PBLs reactive with an HLA-A*11:01, G12D-mutated pancreatic cell line could significantly reduce its growth in NSG mice (P = 0.002). The success of adoptive transfer of TCR-engineered T cells against melanoma and other cancers supports clinical trials with these T cells that recognize mutated KRAS in patients with a variety of common cancer types. Cancer Immunol Res; 4(3); 204–14. ©2015 AACR.