RELATIONSHIP BETWEEN ZCE-025 BLOOD CLEARANCE AND LIVER ACCUMULATION IN PATIENTS WITH COLORECTAL-CANCER

Clinical interest in radiolabelled monoclonal antibodies (mAbs) derive s from their ability to target tissues and deliver radioisotopes there to. Diagnostic and therapeutic trials suggest that the potential of mA bs would be optimized with better understanding of factors which influ ence blood clearance. This study sought to advance that understanding. Nine colon cancer patients were injected with 20 mg In-111 radiolabel led ZCE 025 mAb, then laser-positioned and imaged daily for one week v ia nuclear medicine views. Laser-positioned CT images were also obtain ed, enabling image registration. Blood samples were taken at 30, 60, a nd 90 min and at every imaging time point. Sample activity was plotted to estimate the elimination half-life (t(1/2) beta) Liver radiation d ose was calculated from the images and evaluated for total organ (mCi- h) and region of interest (mu Ci-h/g). Laboratory values and patients' physical parameters were also studied to determine their impact on li ver uptake and mAb blood clearance. Liver radiation dose, as measured in this study, correlated with terminal half-life of the mAb in blood; patients' liver enzymes and physical parameters did not, Radioactivit y in a 48-h or 72-h blood sample correlates with t(1/2) beta and liver radiation dose, suggesting that a single 72-h sample can predict both .