Efficacy, Toxicity, and Prognostic Factors of Re-treatment With [177Lu]Lu-DOTA-TATE in Patients With Progressing Neuroendocrine Tumors: The Experience of a Single Center

Purpose: Peptide receptor radionuclide therapy (PRRT) is an effective and safe treatment of unresectable or metastatic, progressive neuroendocrine tumours (NETs). However, if progression occurs after the initial PRRT, treatment options remain limited. Our aim was to evaluate the efficacy and safety of a repeat (177)Lutetium-[DOTA°,Tyr(3)]octreotate ([(177)Lu]Lu-DOTA-TATE) PRRT course in patients with progressive NET after the first [(177)Lu]Lu-DOTA-TATE PRRT (peptide receptor radionuclide therapy first treatment (PRRT1)). Methods: This is a nine-year retrospective observational study of 20 patients who were re-treated with PRRT (peptide receptor radionuclide therapy retreatment (PRRTR)) after PRRT1. Results: The median progression-free survival (PFS) following PRRT1 was 32 months (interquartile range (IQR): 16.5-44.5). After PRRT1, all 20 patients progressed. Of the 20 patients included, two were lost during follow-up. The median PFS after PRRTR was 17.5 months (IQR: 7-39). At the time of analysis, 15/18 patients progressed, and 3/18 had stable disease after PRRTR. Among those patients who progressed, the median time to progression was nine months (IQR: 0-17). The median overall survival from the time of the first cycle of PRRT1 was 66 months (IQR: 65-90). No significant renal or liver toxicity was reported, nor was there a drop in haemoglobin. The decrease in platelet count after PRRTR was statistically significant (p=0.03). Two cycles at PRRTR (vs. 1) were associated with a longer PFS (p=0.014) and the presence of metastases pre-PRRTR was associated with a shorter time to progression following PRRTR (p=0.04). Conclusion: Patients who progressed after PRRT1 can achieve good PFS and minor toxicity. Our study reinforces the efficacy and safety of PRRTR and provides an analysis of factors associated with better outcomes, which can aid clinicians in clinical decision-making.