Radioimmunodetection of Metastatic Colorectal Cancer Using Monoclonal Antibody

Junichi Sakamoto, Tomoyuki Kato, Hiroaki Nakazato, Tadashi Watanabe¹⁾, Hiroki Murayama¹⁾, Kimio Wada¹⁾, Hiroshi Takagi¹⁾

Department of Gastroenterological Surgery, Aichi Cancer Center
Second Dapartment of Surgery, Nagoya University School of Medicine¹⁾

H-15, a mouse monoclonal antibody was established and selected for a tumor localization study because the antigen was shown to be expressed in a high percentage of primary and metastatic colorectal cancers. The epitope recognized by H-15 is a neuraminidase sensitive glycoprotein (200 kd) and close cross reactivity with sialyl-Le^a determinant was detected by the inhibition test. Tumor imaging with human colorectal tumor bearing nude mice using ¹²⁵I-labeled H-15 was successful. H-15 labeled with ¹³¹I was given intravenously over a dose range of 0.2 mg-10 mg to 28 patients with colorectal tumors. No significant toxicity or side effects were seen. Direct tumor imaging was successful in 4 out of 20 hepatic metastases and 3 out of 8 local lesions from days 4-6 after the antibody injection. Thus, tissue biopsy specimens and scintigraphy have proved that imaging of metastatic colorectal cancer is possible with monoclonal antibody H-15. For the precise localization of tumor imaging, ^99mTc-MPD was infused simultaneously, and the specific location was demonstrated by a subtraction study.

Key words
tumor imaging, radioiodinated monoclonal antibody, colorectal cancer

Reprint requests
Junichi Sakamoto Department of Gastroenterological Surgery, Aichi Cancer Center
1-1 Kanokoden, Chikusa-ku, Nagoya, 464 JAPAN

Accepted
November 8, 1989

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