Published in Cancer Detection and Prevention 2000; 24(Supplement 1).

Human monoclonal antibody SK-1 immunotargeting therapy for recurrent colorectal cancers

K Koda MD PhD, J Yasutomi MD PhD, N Takiguchi MD PhD, K Oda MD PhD, N Nakajima MD PhD

Dept Surgery I, Chiba University School of Medicine, Chiba, Japan,

AIM: A human IgM monoclonal antibody SK1 recognizes a glycoprotein that is expressed on the adenocarcinoma tissues. We have reported that the antigen may correlate with the invasion capacity of adenocarcinomas, and that SK1 inhibits cancer cell migration almost completely (Br J Cancer, 1998). Recently we identified the antigenic 20 amino acids by constructing the cDNA expression library from a colon cancer cell line and screening with SK1 (Tissue Antigens, 2000). Positive immunoscintigram was obtained in colon cancer patients using SK1 (Int J Immunother, 1998). In this study, the safety, toxicity, and preliminary efficacy was evaluated for the immunotherapy using SK1. METHODS: A standard phase I/IIa study was performed, in which SK1 was administered intravenously at 2, 4 or 10 mg once every two week for a total of four weeks (i.e. three administrations) to three groups of three patients with recurrent colon cancer who had been extensively pretreated. RESULTS: No complete responses or partial responses of the tumors to the therapy were observed. However, in six patients, the rate of serum CEA level increase declined significantly during the four weeks following the treatment, and this trend continued for the next four weeks (p< 0.05). In four patients, serum titer of anti-idiotypic IgG antibodies to SK-1 (Ab2) continued to increase during the eight weeks following the treatment. CONCLUSION: It was suggested that SK1 not only possessed direct cytostatic activity against colon carcinoma, but may also have induced carcinoma-related, anti-idiotypic antibody responses.

KEY WORDS: human monoclonal antibody, clinical trial, colorectal cancer, immunotherapy.

For more information, contact

Paper presented at the International Symposium on Impact of Biotechnology on Cancer Diagnostic & Prognostic Indicators; Geneva, Switzerland; October 28 - 31, 2000; in the section on immunotherapy.