Pharmacokinetics of indium-111 labeled 10-3D2 antibreast-tumor antibody in patients.

In a program to investigate patient pharmacokinetics of labeled anti-tumor antibodies, a study of the 10-3D2 anti-breast tumor antibody was conducted. The F(ab')2 fragment, coupled with DTPA, was radiolabeled with indium-111 and 1 mg (37 MBq, or 1 mCi) administered to each of 7 patients with documented or suspected breast carcinoma. Abnormal accumulations of radioactivity were observed in only one patient even though 5 had evidence of disease at the time of imaging. Despite the reported absence of circulating antigen to this antibody, sera from one patient showed evidence of a high molecular weight immune complex by size exclusion HPLC. However, this patient had detectable circulating HAMA, which cannot be excluded as the cause of such immune complex. Urine excretion of radioactivity varied greatly from patient to patient (from 2-34% ID within the first day) but the mean value (0.22% ID/hour) was equal to that seen by us in previous studies. The biodistribution of the label was found to be unusual in that kidney levels increased in all patients during the first day and, in particular, liver radioactivity levels decreased in all patients.