Radiolabeled antibody imaging in the management of colorectal cancer. Results of a multicenter clinical study.

Presurgical colorectal cancer patients (n = 116) received single intravenous infusions of 1 mg of CYT-103 (OncoScint CR103), an immunoconjugate of monoclonal antibody B72.3, radiolabeled with 111In. Following gamma camera imaging, 103 patients underwent an operative procedure: 92 had primary or recurrent colorectal carcinoma, 1 patient evaluated for recurrence of colorectal cancer had a second primary malignancy (small cell lung), and 10 patients had no demonstrable evidence of malignancy. 111In-CYT-103 immunoscintigraphic findings were consistent with the pathologic diagnoses for 70% of patients with colorectal cancer and 90% of disease-free patients. Antibody imaging contributed to surgical decision making through the detection of occult disease (12% of patients) and the confirmation of localized, potentially resectable disease without regional or metastatic spread. Seven patients (6%) experienced adverse effects, primarily fevers and itching, and 33% of patients developed antibodies to murine immunoglobulin after administration of 111In-CYT-103. The results of this study suggest that 111In-CYT-103 is a useful diagnostic tool for the presurgical evaluation of colorectal cancer patients.