Biomarkers in neuroendocrine tumors.

Neuroendocrine tumors are a heterogeneous group of tumors with cells of neuroendocrine differentiation that arise from diverse anatomic sites with varying morphologic and clinical features. Since the natural history and prognosis varies widely between individual neuroendocrine tumor types, there is a critical need to identify accurate prognostic and predictive biomarkers and markers predictive of therapeutic efficacy. To date, plasma chromogranin-A levels have generally been accepted as the most useful biomarker, despite the fact that there are substantial concerns in sensitivity and discrepancies in measurement techniques. As a consequence, considerable attention has been focused upon the development of novel biomarkers that can be utilized with more clinical efficacy than chromogranin-A. In addition to amplifying the diagnostic/prognostic landscape, the need to calibrate the efficacy of biological targeted therapy has further accelerated the development of molecular biomarkers. At the 2013 American Society of Clinical Oncology (ASCO) Annual Meeting, Chou et al. (Abstract #e15151) presented data that chromogranin A levels can be monitored during treatment to predict clinical outcome. Modlin et al. (Abstract #4137), demonstrated a promising novel biomarker, serum multi-transcript molecular signature. Grande et al. (Abstract #4140), Heetfield et al. (Abstract #e15071) and Casanovas et al. (Abstract #4139) described sVEGFR2, p-mTOR and IGF1R as molecular markers with potential for use in targeted therapy trials. The authors review and summarize these abstracts in this article.