Detection of Somatic Mutations in Gastroenteropancreatic Neuroendocrine Tumors Using Targeted Deep Sequencing.
Mutations affecting the mechanistic target of rapamycin (MTOR) signalling pathway are frequent in human cancer and have been identified in up to 15% of pancreatic neuroendocrine tumours (NETs). Grade A evidence supports the efficacy of MTOR inhibition with everolimus in pancreatic NETs. Although a significant proportion of patients experience disease stabilization, only a minority will show objective tumour responses. It has been proposed that genomic mutations resulting in activation of MTOR signalling could be used to predict sensitivity to everolimus.



Patients with NETs that underwent treatment with everolimus at our Institution were identified and those with available tumour tissue were selected for further analysis. Targeted next-generation sequencing (NGS) was used to re-sequence 22 genes that were selected on the basis of documented involvement in the MTOR signalling pathway or in the tumourigenesis of gastroenterpancreatic NETs. Radiological responses were documented using Response Evaluation Criteria in Solid Tumours.



Six patients were identified, one had a partial response and four had stable disease. Sequencing of tumour tissue resulted in a median sequence depth of 667.1 (range=404-1301) with 1-fold coverage of 95.9-96.5% and 10-fold coverage of 87.6-92.2%. A total of 494 genetic variants were discovered, four of which were identified as pathogenic. All pathogenic variants were validated using Sanger sequencing and were found exclusively in menin 1 (MEN1) and death domain associated protein (DAXX) genes. No mutations in the MTOR pathway-related genes were observed.



Targeted NGS is a feasible method with high diagnostic yield for genetic characterization of pancreatic NETs. A potential association between mutations in NETs and response to everolimus should be investigated by future studies.
Department of Surgical, Uppsala University, Uppsala, Sweden.
Samuel
S
Backman
Department of Surgical, Uppsala University, Uppsala, Sweden.
Olov
O
Norlén
Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
Barbro
B
Eriksson
Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
Britt
B
Skogseid
Department of Surgical, Uppsala University, Uppsala, Sweden.
Peter
P
Stålberg
Department of Surgical, Uppsala University, Uppsala, Sweden joakim.crona@surgsci.uu.se.
Joakim
J
Crona
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D056970:Co-Repressor Proteins; D000068338:Everolimus / Q000627:therapeutic use; D005260:Female; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods*; D006801:Humans; D007414:Intestinal Neoplasms / Q000188:drug therapy / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D018832:Molecular Chaperones; D009154:Mutation; D018358:Neuroendocrine Tumors / Q000188:drug therapy / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D012189:Retrospective Studies; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000235:genetics*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D016896:Treatment Outcome
D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents; D056970:Co-Repressor Proteins; C106985:DAXX protein, human; C105373:MEN1 protein, human; D018832:Molecular Chaperones; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D000068338:Everolimus; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases
MTOR; PNET; biomarker; next-generation sequencing