Development of radioactively labelled cancer seeking biomolecules for targeted therapy

A preliminary clinical trial aimed at evaluating the biodistribution and dosimetry of DOTATOC radiolabeled with 111In was undertaken in anticipation of therapy trials with 90Y-DOTATOC. Twenty patients with neuroendocrin tumours were injected with about 200 MBq of 111In-DOTATOC. The patients were hospitalized for 3 days in order to collect all the necessary data and perform the scintigraphic examinations. A complete urine collection and a series of blood samples were withdrawn in order to study pharmacokinetics. The activity in the samples was determined by a γ-counter. Biodistribution was evaluated by scintigraphic images. The 111In-DOTATOC showed favorable pharmacokinetics (fast blood clearance and urinary excretion) and biodistribution, and high affinity to tumours, expressing somatostatin receptors (thus a high residence time in tumour). These results have been considered very promising for therapy trials with 90Y-DOTATOC, for which radiation dosimetry appears to be acceptable for normal organs (including the red marrow). The encouraging results of this dosimetric study have prompted us to explore the best labeling conditions of DOTATOC with 90Y. The labeling procedure has now been optimized