title: Mouse-human chimeric anti-Tn IgG1 induced anti-tumor activity against Jurkat cells in vitro and in vivo.
abstract: Tn-antigen (alpha-N-acetyl-galactosamine(GalNAc)-Ser/Thr) is a cancer-associated carbohydrate antigen expressed in various epithelial and hematological cancers, and although a number of anti-Tn IgG and IgM antibodies have been generated, they have not been fully validated for cancer immunotherapy. In this study, we generated a novel murine anti-Tn IgG1 monoclonal antibody, KM3413, by immunization of mucins purified from a culture supernatant of LS180: a human colon cancer cell line. The binding of KM3413 was detected against consecutive Tn-antigens (Tn3 and Tn2), but not against monovalent antigens (Tn1). The affinity (K(D)) of KM3413 was determined to be about 10(-7) M with BIAcore. Cross-reactivity against type-A blood antigen, which shares a sugar residue, alpha-linked GalNAc, with Tn-antigen, was not detected. Next, we generated mouse-human chimeric IgG1 of KM3413 (cKM3413) and evaluated its anti-tumor activities against Jurkat: a human T-lymphoid leukemia cell line. In vitro assay revealed that cKM3413 induced antibody-dependent cellular cytotoxicity (ADCC) and direct killing activity with cross-link antibody. Furthermore, treatment of cKM3413 (1 or 10 mg/kg) showed significantly better survival of Jurkat-inoculated C.B-17/lcr-scid Jcl mice compared with controls using PBS treatment (p<0.001). These results suggest that humanized antibody against clustered Tn-antigens is a promising therapeutic antibody against Tn-positive cancers.
authors.affiliation: Antibody Research Laboratories, Kyowa Hakko Kogyo Co., Ltd, Machida, Tokyo, Japan. hiroshi.ando@kyowa.co.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ando
authors.forename: Takefumi
authors.initials: T
authors.lastname: Matsushita
authors.forename: Masako
authors.initials: M
authors.lastname: Wakitani
authors.forename: Takashi
authors.initials: T
authors.lastname: Sato
authors.forename: Sachiko
authors.initials: S
authors.lastname: Kodama-Nishida
authors.forename: Kenji
authors.initials: K
authors.lastname: Shibata
authors.forename: Kenya
authors.initials: K
authors.lastname: Shitara
authors.forename: So
authors.initials: S
authors.lastname: Ohta