Endocrine Abstracts

Introduction: ¹⁷⁷Lu-Oxodotreotide(PRRT-Lu) has the approval by EMA and FDA since 2017 for the treatment of patients with gastro-entero-pancreatic neuroendocrine tumors(GEP-NET). However, in daily clinical practice it has also been used in other NET tumors such as paragangliomas, lung NET, medullary thyroid cancer, and others. The aim of this study is to describe the characteristics and follow-up of patients treated with PRRT-Lu in a third level hospital in Spain from 2015-2022.

Methods: Descriptive and transversal study of 103 patients with NET and positive expression for somatostatin receptors, in advanced stage or progressive disease treated with PRRT-Lu. Characteristics and follow-up of the patients are expressed as media or percentage (SPSSv26.)

Results: – Mean age at treatment was 63 years(SD14). 49.5% were men. PRRT-Lu was administered in 85% NETs, 10.2% PG/PHEO, 0.9% medullary thyroid cancer.

– Primary tumor localization: 36.5% pancreas, 23.4% small intestine, 13.1% lungs, 7.5% suprarenal glands, 8.4% unknown primary.

– The treatment was administered every 8 weeks following standard PRRT-Lu recommendation: 60.7% received 4 doses, 10.3% 3 doses, 9.3% 2 doses, 12.1% 1 dose. 4 patients have been retreated during follow-up.

– 99% of the patients received prior treatments, 87% SSA, 23% chemotherapy, 40.7% everolimus, 23.3% sunitinib. PRRT-Lu was used as 1st line of treatment in 1 patient, 2nd line in 44 patients (42.3%), 3rd line in 75 patients (72.1%), 4th line in 12 patients (11.5%), and as 5th line in 10 patients (9.6%).

– Median follow-up is 17.9 months(IQR 25.6), with a maximum follow-up 68 months. During follow up according to RECIST criteria: 38.3% Stable Disease, 29% progressive disease, 7.5% partial response, and 21% NA (6.5% lost follow-up, 14.5% have just started treatment).

– Adverse effects: 60.7% did not have any adverse event, 11.2% gastrointestinal, 5.6% hematologic, 10% asthenia, all of them G1-G2. Only one patient had a severe adverse event, a medullary aplasia that caused death. Metabolic complications presented with the administration of the medication were: diabetic ketoacidosis, severe hyperkalemia, hypertensive crisis, and uncontrolled VIPOMA crisis.

Conclusion: – Treatment with 177Lu-Dotatate must be considered as a treatment of advanced NETs with positive expression of somatostatin receptors, because of the favorable results in PFS and safety.

– Patients should be assessed within a multidisciplinary committee and framed in Reference Units, given their therapeutic complexity.

– The endocrinologist’s role in monitoring the patient must be a cornerstone, in order to detect and treat endocrinological complications before, during and after treatment.