Phase I trial of iodine 131-labeled COL-1 in patients with gastrointestinal malignancies: influence of serum carcinoembryonic antigen and tumor bulk on pharmacokinetics.

PURPOSECOL-1 is a high-affinity murine monoclonal antibody (MAb) specific for carcinoembryonic antigen (CEA). A phase I trial was conducted in which a uniform quantity of antibody labeled with escalating doses of iodine 131 (131I) was administered to patients with advanced gastrointestinal (GI) malignancies to evaluate tolerance and pharmacokinetics.PATIENTS AND METHODSEighteen patients with advanced, assessable GI malignancies (16 colon, one pancreas, and one gastric) previously treated with conventional chemotherapy (but no pelvic radiation) received 20 mg of COL-1 labeled with 131I, with doses from 10 mCi/m2 to 75 mCi/m2. In this cohort, the baseline serum CEA level ranged from 6 to 2,739 ng/mL (mean +/- SD, 500 +/- 639).RESULTSNuclear imaging detected at least one tumor site in all 18 patients; 82% of all tumor involved organs were positive and 58% of all lesions > or = 1.0 cm were detected. Immune complexes were detected in 89% of patients 5 minutes after completion of infusion, and levels correlated...