Efficacy of Peptide Receptor Radionuclide Therapy in a United States-Based Cohort of Metastatic Neuroendocrine Tumor Patients Single-Institution Retrospective Analysis

Objectives: The aimof this study was to analyze in a retrospective cohort study the outcomes of a United States-based group of metastatic neuroendocrine tumor (NET) patients who underwent peptide receptor radionuclide therapy (PRRT). Methods: Twenty-eight patients from a single US NET Center were treated with PRRT. Toxicities were assessed using Common Terminology Criteria for Adverse Events version 4.03. Progression was determined by the Response Evaluation Criteria in Solid Tumors version 1.1. Univariate andmultivariate Cox regression was performed to identify potential predictors of progression-free survival (PFS) and overall survival (OS). Results: The median age at NET diagnosis was 56 years, 50% of the patients were male, 46% of NET primaries were located in the pancreas, 71% of tumors were nonfunctional, 25% were World Health Organization (WHO) grade III, and 20% had at least a 25% hepatic tumor burden. Anemia (36%) was the most common post-PRRT toxicity, followed by leukopenia (31%), nephrotoxicity (27%), and thrombocytopenia (24%). Median PFS was 18months, andmedian OS was 38months. Having aWHO grade III NETand receiving systemic chemotherapy prior to PRRTwere found to be to independent predictors of shorter PFS and OS. Conclusions: Peptide receptor radionuclide therapy is an effective therapy in a US population. Progression-free survival and OS were better in WHO grade I/II NETs and when PRRT was sequenced prior to systemic chemotherapy.