Tropomyosin receptor kinase (Trk) inhibitors are investigated as a novel targeted therapy in various cancers. We investigated the in vitro effects of the pan-Trk inhibitor GNF-5837 in human neuroendocrine tumor (NET) cells. The human neuroendocrine pancreatic BON1, bronchopulmonary NCI-H727 and ileal GOT1 cell lines were treated with GNF-5837 alone and in combination with everolimus. Cell viability decreased in a time- and dose-dependent manner in GOT1 cells in response to GNF-5837 treatment, while treatment in BON1 and NCI-H727 cells showed no effect on cellular viability. Trk receptor expression determined GNF-5837 sensitivity. GNF-5837 caused downregulation of PI3K-Akt-mTOR signaling, Ras-Raf-MEK-ERK signaling, the cell cycle and increased apoptotic cell death. The combinational treatment of GNF-5837 with everolimus showed a significant enhancement in inhibition of cell viability vs single substance treatments, due to a cooperative PI3K-Akt-mTOR and Ras-Raf-MEK-ERK pathway downregulation, as well as an enhanced cell cycle component downregulation. Immunohistochemical staining for Trk receptors were performed using a tissue microarray containing 107 tumor samples of gastroenteropancreatic NETs. Immunohistochemical staining with TrkA receptor and pan-Trk receptor antibodies revealed a positive staining in pancreatic NETs in 24.2% (8/33) and 33.3% (11/33), respectively. We demonstrated that the pan-Trk inhibitor GNF-5837 has promising anti-tumoral properties in human NET cell lines expressing the TrkA receptor. Immunohistochemical or molecular screening for Trk expression particularly in pancreatic NETs might serve as predictive marker for molecular targeted therapy with Trk inhibitors.
Elke Tatjana Aristizabal Prada, Vera Heinzle, Thomas Knösel, Svenja Nölting, Gerald Spöttl, Julian Maurer, Christine Spitzweg, Martin Angele, Nina Schmidt, Felix Beuschlein, Günter K Stalla, Rainer Blaser, Klaus A Kuhn and Christoph J Auernhammer
Florian Bösch, Katharina Brüwer, Annelore Altendorf-Hofmann, Christoph J Auernhammer, Christine Spitzweg, C Benedikt Westphalen, Stefan Boeck, Gabriele Schubert-Fritschle, Jens Werner, Volker Heinemann, Thomas Kirchner, Martin Angele and Thomas Knösel
Cancer immunotherapy has evolved major breakthroughs in the last years. The cell-surface receptor programmed death-1 (PD-1) and its ligand, programmed death ligand-1 (PD-L1), have been detected in various cancer types. However, the analysis on gastroenteropancreatic neoplasia (GEP-NENs) is limited. Therefore, the aim of this study was to characterize GEP-NENs with regard to PD-1/PD-L1 pathway and tumor-infiltrating lymphocytes (TILs). On protein level, we examined TILs, PD-1 and PD-L1 expression in tumor tissue of 244 GEP-NENs using immunohistochemistry. Expression levels were correlated with clinicopathological parameters including long-term survival in an observational study. In total, 244 patients could be included. Most of the patients had a NEN of the small intestine (52.5%) or the pancreas (29.5%). All tumors could be graded by their morphology and Ki67 index, with 57.8% G1, 34% G2 and 8.2% G3 tumors. High TILs (19.6%) and high PD-1 (16.1%) expression showed a significant correlation with shorter patient survival (P < 0.05) and with a higher grading. Furthermore, expression of PD-L1 (8.7%) showed a trend to shorter patient survival. High TILs and PD-1 expression are significantly associated with shorter patient survival and higher grading in GEP-NENs. PD-L1 expression showed a trend to shorter patient survival. Immunotherapy might be a promising therapeutic approach in GEP-NENs especially in tumors with high TILs.