Efficacy of Peptide Receptor Radionuclide Therapy for Metastatic Inoperable Neuroendocrine Tumors Using 177-Lu-DOTA 0, Tyr 3 Octreotate

Well-differentiated neuroendocrine tumors (WDNETs) are uncommon neoplasms with an increasing number of new cases reported in the annual statistics of the Instituto Nacional de Cancerología (INC). The majority are advanced-stage presentations with limited chances of a complete surgical resection of the primary tumor, a clinical scenario where medical treatment options are also limited. In view of the characteristically defined expression of peptide receptors in WDNETs, radioactive molecular probes to target specific cellular receptors have been designed using radioisotopes with short range of penetration in tissues. We have designed a one-arm phase II prospective sequential clinical trial to assess the therapeutic efficacy of 177-Lu-[DOTA 0, Tyr 3] octreotate (177-Lu- DOTATATE) applied intravenously in three separate doses to patients with inoperable progressive WDNET. Selected patients matching inclusion criteria will be enrolled at the INC's Section of Endocrinology. Tumor response, treatment safety (side effects) and survival will be appraised. Data from clinical, biochemical and imaging follow-up will be periodically registered during treatment and until two years after the last infusion of 177Lu- DOTATATE. This phase II trial is justified because despite the fact that many preclinical and clinical studies have showed the potential usefulness of this novel palliative approach to treat patients with advanced-stage WDNETs there is a paucity of vigorous results to establish its efficacy as first-line treatment.