A Monoclonal Antibody, KM10 Reactive with Human Gastrointestinal Cancer and Its Application for Immunotherapy

Abstract

A monoclonal antibody, KM10 (IgG1) was produced by fusing spleen cells from a human gastric cancer cell (MKN45)‐primed BALB/c mouse with the murine myeloma cell line X63‐Ag8‐653. The antibody reacted strongly with the plasma membrane of human gastrointestinal carcinoma. Sections of the malignant and benign tissues were tested with immunoperoxidase. All of 10 (100%) large intestinal cancers, 26 of 31 (84%) gastric cancers, 5 of 7 (71%) pancreatic cancers and all of 3 (100%) ampullary cancers reacted positively. Moderate or weak reactivity was observed with normal human tissues, hepatoma and carcinomas of mammary, thyroid and adrenal glands. According to a study of the distribution of 125I‐labeled KM10 in nude mice bearing human gastric cancer, KM10 selectively localized in tumor tissue rather than normal tissue. Whole body autoradiography also supported such a selective distribution. Destruction of antigenic properties by pronase digestion demonstrated its protein nature and by Western blot analysis, it was identified as a protein with an Mr of 180–200 kd. KM10‐adriamycin (ADM) conjugate was prepared via an oxidized dextran bridge and this immunoconjugate retained the binding activity against human gastric cancer. MKN45 cells were inoculated subcutaneously into athymic mice and intravenous treatment was begun when the tumor became measurable. A dose‐dependent antitnmor activity was observed in vivo with KM10‐ADM conjugate, while this conjugate was less toxic than free ADM.

Development of monoclonal antibodies against human gastrointestinal cancer.

“…Soyama et al (1989) suggested that KM10 recognized the distinctive part CEA by the mutual inhibition assay using these antibodies. Ohyanagi et al (1988) showed that the molecular weight of the antigen recognized by KM10 was about 180 kDa and this protein was also recognized by anti-CEA monoclonal antibody. Ishida et al (1988) reported that the antigenic epitope of KM10 was resistant against neuraminidase treatment and sodium periodate treatment, while sensitive to pronase treatment.…”

“…From the results of the electron microscopic observation, the antigen recognized by KM1O is highly expressed on the surface of cancer cells. Ohyanagi et al (1988) reported the strong antitumor effect of KM10-adriamycin conjugate in tumor xenograft. They showed the dose-sependent antitumor activity of KM10-adriamycin conjugate, while this conjugate was less toxic than free adriamycin.…”

Selection of monoclonal antibodies detecting KM01 antigen.

“…We also have been developing new MoAbs useful for the diagnosis and therapy of cancer (Ohyanagi et al 1988; Kano et al 1990a), some of which were found to be cross-reactive with KMO1. They were divided into three groups depending on their reactivity with glycolipid antigens isolated from COLO-201.…”

Effects of neocarzinostatin-chimeric Fab conjugates on the growth of human pancreatic carcinoma xenografts

“…While new therapeutic methods including chemotherapy, radiation and hyperthermia have been developed for treating patients with advanced pancreatic cancer, in most cases they do not completely suppress cancer growth. Recently, research has been directed towards the use of monoclonal antibody (MAb)-drug conjugates for solid tumours (Deguchi et al, 1987;Apelgren et al, 1990;Ohyanagi et al, 1988). This has been made possible by the availability of MAbs that recognise cell surface antigens of carcinomas.…”