A Novel Anti-Cadherin-17 Monoclonal Antibody, Ca17Mab-5, for Multiple Applications

Background/Objectives: Cadherin-17 (CDH17, LI-cadherin) is a non-classical cadherin with an atypical structure and unique functions. CDH17 expression is restricted to normal intestinal epithelium. Furthermore, CDH17 functions as an oncoprotein that promotes tumor migration and invasion in colorectal, gastric, and pancreatic cancers. Therefore, CDH17 is an important diagnostic marker and therapeutic target. The CDH17-directed strategies, including monoclonal antibodies (mAbs), bispecific Abs, antibody–drug conjugates (ADCs), and chimeric antigen receptor (CAR) T cells, have been evaluated in preclinical and clinical studies. Therefore, developing mAbs that specifically recognize cell surface-expressing CDH17 is essential for advancing both tumor diagnosis and therapy. Methods: Anti-human CDH17 mAbs (named Ca17Mabs) were developed by immunizing a mouse with CDH17-overexpressed cells and a high-throughput screening using flow cytometry. Results: Among Ca17Mabs, a clone, Ca17Mab-5 (IgG1, κ) specifically recognized CDH17-overexpressed Chinese hamster ovary-K1 (CHO/CDH17) cells with no detectable cross-reactivity to 21 other CDHs by flow cytometry. Ca17Mab-5 also detected endogenous CDH17 in human colorectal cancer cell lines, COLO201 and COLO205. The dissociation constant (KD) values of Ca17Mab-5 for CHO/CDH17 and COLO205 were estimated as 1.4 × 10−8 M and 1.3 × 10−8 M, respectively. Furthermore, Ca17Mab-5 detected endogenous CDH17 by Western blotting. In immunohistochemistry, Ca17Mab-5 exhibited clear membranous staining in normal colon epithelium and colorectal cancers. Conclusion: Ca17Mab-5 is a versatile tool for detecting CDH17 and has potential for tumor diagnosis and therapy.