90-Yttrium-DOTA-octreotate for the treatment of advanced neuroendocrine tumors

Abstract

4594Background: The expression of somatostatin receptors (SSTR) on Neuroendocrine Tumors (NETs) has led not only to tumour visualization utilizing SSTR scintigraphy, but also to the development of receptor-targeted radionuclide therapy. Isotopes such as 111-Indium, 90-Yttrium and 177-Lutetium are linked to somatostatin analogues and then internalized by tumour cells. The recent development of the peptide Octreotate has higher affinity for type 2 SSTR than Octreotide. Aim: to estimate efficacy and tolerability of 90-Yttrium-tyr3-DOTA-octreotate in patients with metastatic progressive NETs. Methods: 89 patients (median age: 51.5 years) with metastatic NETs were studied. All patients had shown signs of progression despite previous treatments. In all patients, the tumours had shown good uptake either in the OctreoScan or in the Ga-68 octreotate PET scan. 64 patients received 3 cycles and 25 patients received 2 cycles of 90-Yttrium-tyr3-DOTA-octreotate. The mean i.v. dose/cycle was 3100 MBq. 29/89 patients included a cycle of intra-arterial therapy with mean dose/cycle 2090 MBq for large volume liver disease. Symptomatic response to treatment was defined as the reduction of >50% to the symptom score and radiological response utilized RECIST criteria. Results: In all patients the post treatment scintigraphy demonstrated good uptake and localization by the tumors. In 59/89 (66%) symptomatic response was achieved. Utilizing RECIST criteria, 50/89 (56%) had disease stabilization (SD) of previously progressive disease and 7 (8%) had partial response (PR). 31/89 (35%) had continued tumor progression. The SD/PR (n=57) group had sustained response for median 17.2 months. Bone marrow toxicity (WHO grade II) was noted in 15/89 (16.8%), persistent in 4 patients with significant bone metastases. Four patients developed mild renal failure (WHO grade II), that was irreversible in one of them. Conclusions: 90Y-DOTA-octreotate is a well-tolerated and safe treatment for patients with progressive neuroendocrine tumors. Early results regarding efficacy are promising.No significant financial relationships to disclose.