Abstract

We report a pilot study of radioimmunoscintigraphy (RIS) and operative gamma probe scintimetry (OPS) using a 99mTc-labeled anti-cytokeratin human monoclonal antibody (MAb) (99mTc-88BV59) in patients with newly diagnosed, recurrent or metastatic colorectal cancer.

METHODS: Twelve presurgical patients with biopsy- or contrast radiographic-proven colorectal cancer or recurrent colorectal carcinoma were studied. After chest roentgenography and abdominopelvic CT, 99mTc-88BV59 was administered intravenously, planar and SPECT external imaging was performed 3 to 6 hr after injection and planar imaging was performed 18 to 24 hr after injection. Surgery was performed immediately after late planar imaging. OPS of a standardized list of sites to document background radiation activity and of tumor sites, resection margins and tumor beds was performed.

RESULTS: The patients had 23 histologically proven tumor sites. Overall sensitivity for CT, planar RIS, SPECT, surgery and OPS was 43%, 61%, 78%, 96% and 91%, respectively. SPECT was superior to CT for imaging extrahepatic abdominal and pelvic disease. OPS detected all liver and extrahepatic abdominal tumor sites and correctly predicted histological tumor-free margins and tumor beds in all cases. OPS did not identify tumor deposits that the surgeon could neither see nor feel. No patient demonstrated human anti-human immune responsiveness 1 and 3 mo after 99mTc-88BV59 infusion.

CONCLUSION: Technetium-99m-88BV59 is a safe, effective radioimmunoconjugate for colorectal cancer imaging, with superior sensitivity as compared to CT.