Endocrine Abstracts

Although neuroendocrine tumours (NET) constitute a very heterogeneous group, they express somatostatin receptors in more than 80% of cases that allows for their effective diagnosis and treatment with somatostatin analogues. Introduction in the recent years of new somatostatin analogues and chelators feasible for labelling with radiometals allowed for development of new therapeutic strategy – radiopeptide therapy. The aim of the work is to present experience with ⁹⁰Y-DOTATATE therapy of NET.

Material and Methods: Patients with advanced tumours, who were not candidates for standard therapy, were recruited to the study. In all cases the diagnosis of NET was bases on histopathology or cytological examination and the expression of somatostatin receptors was proved in 111In-OctreoScan scintigraphy. Other diagnostic procedures included radiological examinations and blood samples evaluations.

60 to 80 mCi of ⁹⁰Y-DOTATATE treatment was delivered i.v. Patients were scheduled to 4 cycles of therapy administered in 3 months intervals. Before and after the injections of radiolabelled peptide, aminoacide solution was administered to inhibit tubular reabsorption of radiopeptide.

Results: 17 patients were recruited into the study until September 2005. Eight of them (47%) received at least two cycles of therapy and were evaluated for efficacy and toxicity of the treatment. ⁹⁰Y-DOTATATE application was well tolerated. Two patients suffered from nausea and vomits. There were no grade III blood toxicity. Partial remission was achieved in 2. In both of them radiological response was followed by decrease in chromogranin A. In the other 6 patients stable disease was diagnosed. CgA concentration did not change in 5 of them and in one increased during the therapy.

Conclusions: ⁹⁰Y-DOTATATE therapy is well tolerated and can result in tumour objective response in patients with somatostatin receptor-positive NET who are not candidates to other therapeutic modalities.