Chromogranin A and neuron-specific enolase as prognostic markers in patients with advanced pNET treated with everolimus.

Abstract

Everolimus, an oral inhibitor of mammalian target of rapamycin, significantly prolongs progression-free survival (PFS) in patients with advanced pancreatic neuroendocrine tumors (pNET). Chromogranin A (CgA) and neuron-specific enolase (NSE) are considered general biomarkers of these tumors. The objective of the study was to evaluate the prognostic value of CgA and NSE in patients with pNET treated with everolimus. Patients with low- to intermediate-grade advanced pNET enrolled in two phase 2 studies [RAD001 in Advanced Neuroendocrine Tumors (RADIANT-1) and single institution phase II study at The University of Texas M. D. Anderson Cancer Center] received everolimus. Blood samples were collected and analyzed by a central laboratory at baseline and monthly thereafter. PFS and overall survival (OS) were evaluated in patients with elevated and nonelevated baseline CgA/NSE levels. In RADIANT-1, elevated vs. nonelevated baseline CgA was associated with shorter median PFS (8.34 vs. 15.64 months; P = 0.03) and OS (16.95 months vs. not reached; P < 0.001). Elevated vs. nonelevated baseline NSE resulted in shorter median PFS (7.75 vs. 12.29 months; P = 0.01) and OS (13.96 vs. 24.90 months; P = 0.005). Median PFS was prolonged in patients with early CgA or NSE response (11.0 vs. 5.0 months) compared with those without early biomarker response. More patients with CgA (87 vs. 50%) or NSE (81 vs. 14%) response experienced tumor shrinkage compared with those without response. CgA response data from the single-institution phase II study at The University of Texas M. D. Anderson Cancer Center study are consistent with data from the RADIANT-1 study. Elevated baseline CgA/NSE provided prognostic information on PFS and survival; early CgA/NSE responses are potential prognostic markers for treatment outcomes in patients with advanced pNET.