Real-World Outcomes of [¹⁷⁷Lu]Lu-DOTA-TATE Peptide Receptor Radionuclide Therapy in Patients with Metastatic Gastroenteropancreatic Neuroendocrine Tumors: Data from a Belgian ENETS Center of Excellence

Background and study aims: Peptide receptor radionuclide therapy (PRRT) has been reimbursed in Belgium since 2022. Post marketing monitoring of efficacy in Belgian context has not yet been performed. This study aimed to evaluate the efficacy and safety of PRRT in patients with progressive metastatic gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Patients and methods: Lu] Lu-DOTA-TATE at Institute Jules Bordet (Brussels, Belgium) between 2013 and 2023. Treatment response was assessed according to RECIST 1.1 (Response Evaluation Criteria in Solid Tumors). Progression free survival (PFS) and overall survival (OS) were estimated using Kaplan-Meier analysis. Treatment safety profiles were reported descriptively. Results: Following initial PRRT (PRRT-1), in 110 patients with progressive metastatic GEP-NETs (grades 1-3), median PFS was 22.5 months (95% CI: 19.7-29), and median OS was 42.3 months (95% CI: 34.3-55). RECIST 1.1 responses were complete response in 1%, partial response in 21.6%, stable disease in 60.8%, and progression in 16.7% of patients. Median time of follow-up post PRRT-1 was 26.4 months (range: 0.8 - 106.4). Grade 3-4 anemia, leukopenia, lymphopenia and thrombocytopenia occurred in 1.9%, 2.8%, 50.5% and 2.8% of patients, respectively. Two patients (1.8%) developed myelodysplastic syndrome. Grade 3 or 4 renal toxicity was observed in two patients who had impaired renal function prior to PRRT. Conclusion: Post-marketing analysis in an ENETS Center of Excellence confirmed that the efficacy and safety of PRRT in GEPNETs are consistent with phase 3 trial data.