Antitumor activities of anti­CD44 monoclonal antibodies in mouse xenograft models of esophageal cancer.

ABSTRACT

CD44 is a type I transmembrane glycoprotein associated with poor prognosis in various solid tumors. Since CD44 plays a critical role in tumor development by regulating cell adhesion, survival, proliferation and stemness, it has been considered a target for tumor therapy. Anti­CD44 monoclonal antibodies (mAbs) have been developed and applied to antibody­drug conjugates and chimeric antigen receptor­T cell therapy. Anti-pan­CD44 mAbs, C44Mab­5 and C44Mab­46, which recognize both CD44 standard (CD44s) and variant isoforms were previously developed. The present study generated a mouse IgG2a version of the anti­pan­CD44 mAbs (5­mG2a and C44Mab­46­mG2a) to evaluate the antitumor activities against CD44­positive cells. Both 5­mG2a and C44Mab­46­mG2a recognized CD44s­overexpressed CHO­K1 (CHO/CD44s) cells and esophageal tumor cell line (KYSE770) in flow cytometry. Furthermore, both 5­mG2a and C44Mab­46­mG2a could activate effector cells in the presence of CHO/CD44s cells and exhibited complement-dependent cytotoxicity against both CHO/CD44s and KYSE770 cells. Furthermore, the administration of 5­mG2a and C44Mab­46­mG2a significantly suppressed CHO/CD44s and KYSE770 xenograft tumor development compared with the control mouse IgG2a. These results indicate that 5­mG2a and C44Mab­46­mG2a could exert antitumor activities against CD44­positive cancers and be a promising therapeutic regimen for tumors.