Effect of Lanreotide Depot/Autogel on Urinary 5-Hydroxyindoleacetic Acid and Plasma Chromogranin A Biomarkers in Nonfunctional Metastatic Enteropancreatic Neuroendocrine Tumors.

backgroundUrinary 5-hydroxyindoleacetic acid (5-HIAA) is an established biomarker in neuroendocrine tumors and carcinoid syndrome; however, its role in nonfunctional neuroendocrine tumors is not defined. We present post hoc data on urinary 5-HIAA and plasma chromogranin A (CgA) from the CLARINET study.

methodsPatients with well- or moderately differentiated, nonfunctioning, locally advanced or metastatic enteropancreatic neuroendocrine tumors were randomized to deep subcutaneous lanreotide depot/autogel 120 mg or placebo once every 28 days for 96 weeks. Tumor response, evaluated centrally (RECIST 1.0), and progression-free survival (PFS) were assessed by treatment and biochemical response, defined as (a) baseline >upper limit of normal (ULN, 41.6 μmol per day 5-HIAA; 98.1 μg/L CgA) and (b) ≥50% decrease from baseline and to ≤ULN value on study.

resultsForty-eight percent (82 of 171; lanreotide,

conclusionsThe 5-HIAA findings are noteworthy because they occurred in patients with nonfunctioning enteropancreatic neuroendocrine tumors. Monitoring 5-HIAA and CgA may be useful when treating patients with nonfunctional neuroendocrine tumors. IMPLICATIONS FOR PRACTICE: Current guidelines focus only on the monitoring of 5-hydroxyindoleacetic acid (5-HIAA) in the diagnosis and management of functional neuroendocrine tumors with carcinoid syndrome. The current post hoc analysis of patients with nonfunctional enteropancreatic neuroendocrine tumors in the CLARINET study demonstrated that measuring and following both 5-HIAA and chromogranin A as biomarkers of disease progression may be useful in the management of patients with nonfunctional neuroendocrine tumors.