Immunotherapy for recurrent colorectal cancers with human monoclonal antibody SK-1

Background: The human monoclonal antibody SK-1 recognizes a glycoprotein ex pressed on the majority of colon cancer tissues. In the current study, we e valuated the safety, toxicity and preliminary efficacy of escalating dosage s of SK-1 in patients with advanced colon cancer. Patients and Methods: SK- 1 was administered intravenously at 2, 4 or 10 mg three times to three grou ps of patients with recurrent colon cancer. The clinical outcome and the in duction of serum anti-idiotypic antibody (Ab2) were assessed periodically. Results: The mean rate of serum CEA level increase declined significantly d uring the eight weeks following the treatment. In four patients, serum tite r of anti-idiotypic IgG antibodies to SK-1 (Ab2) continued to increase foll owing the treatment. Conclusion: HuMAb SK-1 was well-tolerated and can be s afely administered. It was suggested that SK-1 natural antibody not only po ssessed direct cytostatic activity against colon carcinoma, but may also ha ve induced carcinoma-related, anti-idiotypic antibody responses.