The North American Neuroendocrine Tumor Society Consensus Guidelines for Surveillance and Medical Management of Midgut Neuroendocrine Tumors

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

OBJECTIVES

The aim of 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 and multivariate 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 18 months, and median OS was 38 months. Having a WHO grade III NET and receiving systemic chemotherapy prior to PRRT were 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.

Clinical and Preclinical Advances in Gastroenteropancreatic Neuroendocrine Tumor Therapy

The molecular events leading to gastroenteropancreatic neuroendocrine tumor (GEP-NET) formation are largely unknown. Over the past decades, systemic chemotherapies have been replaced by therapies directed at particular molecular targets such as the somatostatin receptors, mTOR complexes or proangiogenic molecules. These approaches have demonstrated some success in subtypes of this heterogeneous tumor group, but responses are still widely varied. This review highlights the clinical trials ongoing for neuroendocrine tumors (NETs) and includes emerging immunotherapy, which holds great promise for NETs based on successes in other tumor types. Current avenues of preclinical research, including Notch and PI3K/AKT, will lead to additional targeted therapies based on genome-wide studies that have cast a wide net in the search for driver mutations. Future preclinical and clinical investigations are required to identify those mutations predictive of therapeutic response or disease progression. Results of current clinical trials outlined here will better inform patient management with respect to agent selection, timing, duration and combination therapy in the treatment of NETs.