Individualized molecular cancer therapy based on radiolabelled somatostatin analogues

Summary

In recent years, different therapeutic approaches have emerged for individualized targeted therapy in tumour patients. It was found that tumours derived from neuroendocrine tissue frequently show somatostatin receptor (SSTR) expression. This property has proven usefulness for imaging neuroendocrine tumours in different clinical situations, e.g. for initial diagnosis and staging, with high diagnostic efficacy. On the basis of these findings tumours were also treated by radiopharmaceuticals showing promising overall results. At our department, patients are selected for radionuclide therapy by their inherent biological characteristic, which can be evaluated by scintigraphy using either with DOTA-TOC or, if this scan is negative, with DOTA-LAN. Recently, these compounds were also labelled with Gallium-68 for PET imaging, providing higher diagnostic quality for initial evaluation and also for follow-up scanning after radionuclide therapy. Individualized therapy in nuclear medicine requires especially optimal functional imaging techniques with PET for visual evaluation and scintigraphy with In-111 labelled compounds for dosimetry. According to our protocol ("Innsbruck Protocol") for peptide receptor radionuclide-therapy with differently labelled tracers (Y-90 or Lu-177) and somatostatin (SST) analogues used, only few serious side effects were observed and therapy was generally well tolerated. These results favour the combined use of radiolabelled SST analogues providing a customized tumour targeting for size reduction and improvement of quality of life. Reduced individual doses make sense in patients with advanced tumour stages, in case of moderate SSTR-expression, and in patients with higher age. Adverse reactions were seen especially in patients who were treated with high doses per cycle, in patients pre-treated with chemotherapy and in patients with low clinical performance index.