Design and Activity of a Murine and Humanized Anti-CEACAM6 Single-Chain Variable Fragment in the Treatment of Pancreatic Cancer

Abstract

Pancreatic ductal adenocarcinoma (PDA) is a lethal disease, with surgery being the only curative modality for localized disease, and gemcitabine with or without erlotinib remains the standard of therapy for unresectable or metastatic disease. CEACAM6 is overexpressed in human PDA independent of stage or grade and causes anoikis resistance when dysregulated. Because murine monoclonal antibody 13-1 possesses target-specific cytotoxicity in human PDA cell lines, we designed a humanized anti-CEACAM6 single-chain variable fragment (scFv) based on monoclonal antibody 13-1. PEGylation of the glycine-serine linker was used to enhance plasma half-life. These scFvs bound CEACAM6 with high affinity, exhibited cytotoxic activity, and induced dose-dependent poly(ADP-ribose) polymerase cleavage. Murine PDA xenograft models treated with humanized scFv alone elicited tumor growth inhibition, which was enhanced in combination with gemcitabine. Immunohistochemistry showed significant apoptosis, with inhibition of angiogenesis and proliferation, and preservation of the target. Collectively, our results have important implications for the development of novel antibody-based therapies against CEACAM6 in PDA.

Protein expression analysis of ALCAM and CEACAM6 in breast cancer metastases reveals significantly increased ALCAM expression in metastases of the skin

“…For both adhesion molecules, antibody studies have revealed possible therapeutic potential in breast and pancreatic cancer 23 24 34 35…”

“…As previous studies suggested an important role for ALCAM localisation in tumour cells, cytoplasmic and membranous ALCAM staining was evaluated separately 16–22. As for both molecules, studies have revealed future therapeutic potential in cancer therapy, and a knowledge of ALCAM and CEACAM6 protein expression levels in distant metastasis is essential 23 24…”

Enhancement of the Antitumor Effect on Combination Therapy of an Anticancer Drug and Its Antibody against Carcinoembryonic Antigen

“…4b). Furthermore, other reports that the anti-CEACAM6 single-chain variable fragment and maytansinoid (tubulin-interacting agent)-conjugated Ab against CEACAM6 led to inhibition of tumor growth might support the importance of preventing CEACAM6, rather than CEA, in the process of anoikis [34,35,36]. Moreover, C2-74 increased cell proliferation in some cases in this study, as shown in figure 3, suggesting that a human anti-CEA Ab does not help reverse the resistance of tumor cells in the metastatic phase.…”

Novel agents for the treatment of adenocarcinoma of the pancreas

“…It is overexpressed in pancreatic cancer cells by activating Ras mutations. CCN2 is thought to protect cells from hypoxia-induced apoptosis, providing a survival advantage for tumor cells under nonideal growth conditions and resulting in increased tumor growth [110]. CEACAM6 (CD66c) is an integral member of the carcinoembryonic antigen (CEA) family and is an important tumorassociated antigen overexpressed in human pancreatic cancer.…”