Assessing the Clinical Impact of Lutetium-177 DOTATATE Peptide Receptor Radionuclide Therapy (PRRT) on Metastatic Neuroendocrine Tumors: A Multicenter Real-World Data from Trkiye

Objectives: This study aimed to evaluate the clinical outcomes, including progression-free survival (PFS), overall sur-vival (OS), Objective Response Rate (ORR), and Disease Control Rate (DCR), in patients received Lutetium-177 (Lu-177) DOTATATE Peptide Receptor Radionuclide Therapy (PRRT) for metastatic neuroendocrine tumors. This study further stratified outcomes based on tumor grade, Ki-67 status, primary tumor localization, number of treatment cycles, and associated adverse effects.Methods: We conducted a multicenter retrospective study analyzing the data of 73 patients with metastatic NETs across 17 different hospitals in various regions of Turkiye. A total of 73 metastatic NET patients underwent Lu-177 DOT-ATATE PRRT between December 2013 and March 2023. Results: Over a median follow-up of 52.7 months, patients showed a median PFS of 13.7 months and OS of 51.2 months. The ORR was 29.6%, and the DCR was 66.2%. Grade 1 and 2 tumor patients had superior outcomes (PFS: 16.9 months, OS: 55.5 months) compared to grade 3 tumor patients (PFS: 8.5 months, OS: 29.5 months). Based on their Ki-67 status, those <= 20% had prolonged PFS (16.9 months) and OS (55.5 months) than those between 21 and 55% (PFS: 5.9 months, OS: 41.3 months). Regarding primary tumor localization, the PFS values were 13.1, 15.3, 13.7, and 8.6 months for pancreatic, GIS, lung, and unknown origin tumors, respectively. The OS across tumor types fluctuated between 41.1 and 54.1 months. Patients who received more than four cycles demonstrated significantly improved median PFS (22.4 months) and OS (90.3 months) compared to those who received <= 4 cycles (median PFS: 9.3 months; median OS: 41.8 months). Grade 3-4 adverse effects were observed in 21.9% of patients.Conclusion: Our findings affirm that PRRT is a potent and well-tolerated treatment for metastatic NETs. Notably, pa-tients who received more than 4 cycles of PRRT experienced a markedly improved median PFS and OS compared to their counterparts who received <= 4 cycles.