Claudin 18.2 targeted proapoptotic peptide for early pancreatic diagnosis and tumor-target killing

Pancreatic adenocarcinoma is a lethal condition with a rising incidence, predicted to become the second leading cause of cancer-related deaths worldwide by 2030. One major hurdle in the treatment of this disease is the predominantly elderly patient population and clinically silent and aggressive nature. Early detection of pancreatic neoplasms and novel treatment for highly aggressive and metastatic conditions is of great need in pancreatic tumor therapy.Claudins are crucial components of tight junctions. They are transmembrane proteins and are the keeper of the “fence function”. Claudins in tumor are like the fall of the soldiers entrusted to protect the gate. Claudin 18.2 is a member of the claudin family, commonly expressed in multiple cancers, including Gastric cancer and Pancreatic cancer. Claudin-18.2 expression on cancer cells is increased and exposed on surface of the cells. The development of malignant tumors leads to the disruption of tight junctions, exposing the Claudin 18.2 epitope on the surface of tumor cells as a specific target. Also, claudin 18.2 is transcriptionally upregulated with the binding of cyclic AMP-responsive element binding protein to the methylated CLDN18.2 promoter region. Claudin 18.2 is considered an early stage marker of pancreatic carcinogenesis. Claudin 18.2 is considered a ‘dark horse' in anti-tumor therapy. Thus, Claudin 18.2 could be a good “target” for early detection and target-specific treatment of pancreatic tumor.Construction of phage peptide library and bio panning for claudin18.2-binding peptides using claudin18.2 overexpressing cells : After five rounds of screening, phage titers that bind to transfected cells were enriched higher-fold compared to phage titers isolated in the first round. 2 phage clones displaying peptides that selectively bound to transfected cells were chosen and sequenced for further study. The two peptides showed selective binding to claudin 18.2 expressing cells as analyzed by Immunofluorescence. Pull down assay further confirmed selective binding of peptide to claudin 18.2. Bioaccumulation study in vivo showed significant accumulation of peptide in tumor tissue. Treatment of KPC transgenic pancreatic tumor bearing mice with claudin 18.2 peptide conjugated to proapoptotic peptide enhanced the survival of the mice. In summary, Claudin 18.2 peptide can specifically target the tumor cells and conjugation with proapoptotic peptide can induce tumor targeted apoptosis with increased survival in pancreatic tumor bearing mice. Claudin 18.2 targeted tumor killing can be a promising approach for pancreatic tumor treatment.