Immunoscintigraphy of colorectal cancer with 111In labeled anti-CEA monoclonal antibody (ZCE-025)

Clinical trials with 111In labeled anti-CEA monoclonal antibody (ZCE-025) was initiated. Five patients with suspected colorectal cancer were given an intravenous injection of 1 mg of 111In labeled ZCE-025. Planar and SPECT images were obtained 24 and 72 hours after injection. Surgical operation was performed on all patients between 7 and 10 days post injection. Of 4 primary sites, all were clearly visualized. Intrahepatic metastasis was visualized as higher activity than normal liver in one of two patients. In one patient whose imaging was negative, no residual cancer was found at surgery. Persistent accumulation of 111In in the lymph nodes was also observed in one patient. Surgical exploration of these lymph nodes showed no gross or microscopic evidence of metastases of colon cancer. No side effects were encountered, although HAMA were detected in all 5 patients by 4 weeks after the administration of ZCE-025. Immunoscintigraphy appears useful in distinguishing recurrent tumor from postoperative granuloma. Further investigation directed to the causes of 111In accumulation in tumor-free lymph nodes is required. (author)