Identification of a peptide binding to cancer antigen Kita‐kyushu lung cancer antigen 1 from a phage‐display library

Abstract

Every year there are nearly 1 million new cases of gastric cancer (GC) reported worldwide, making it the third leading cause of cancerrelated deaths and prompting the World Health Organization to declare it a public health concern. 1 Although the incidence of GC has been substantially declining during the past decades, it remains a high incidence in East Asia. 2 Kita-kyushu lung cancer antigen 1 (KK-LC-1) is a novel tumor target with great therapeutic potential. 3 The KK-LC-1 antigen was originally found in human lung cancer cells but was soon found to be expressed at high levels in breast cancer and GC. [4][5][6] KK-LC-1 is a type of cancer-testis antigen (CTA) that is not be expressed in most normal tissues. Differences between normal and tumor cells are key points of molecular targeted therapy. 7 Small-molecule targeting peptide engineering is a recent area of interest. Compared with antibodies, small-molecule peptides have better tumor permeability, better immunogenicity, and pharmacokinetic parameters. 8 It is worth noting that smallmolecule targeting peptides still have high affinity and selectivity for tumor antigens. These tumor-specific drugs without the structure of immunoglobulins are also called new-generation antibody-like drugs. 9