PURPOSE

Although large-cell neuroendocrine carcinoma (LCNEC) of the lung shares many clinical characteristics with small-cell lung cancer (SCLC), little is known about its molecular features. We analyzed lung LCNECs to identify biologically relevant genomic alterations.

EXPERIMENTAL DESIGN

We performed targeted capture sequencing of all the coding exons of 244 cancer-related genes on 78 LCNEC samples [65 surgically resected cases, including 10 LCNECs combined with non-small cell lung cancer (NSCLC) types analyzed separately, and biopsies of 13 advanced cases]. Frequencies of genetic alterations were compared with those of 141 SCLCs (50 surgically resected cases and biopsies of 91 advanced cases).

RESULTS

We found a relatively high prevalence of inactivating mutations in TP53 (71%) and RB1 (26%), but the mutation frequency in RB1 was lower than that in SCLCs (40%, P = 0.039). In addition, genetic alterations in the PI3K/AKT/mTOR pathway were detected in 12 (15%) of the tumors: PIK3CA 3%, PTEN 4%, AKT2 4%, RICTOR 5%, and mTOR 1%. Other activating alterations were detected in KRAS (6%), FGFR1 (5%), KIT (4%), ERBB2 (4%), HRAS (1%), and EGFR (1%). Five of 10 cases of LCNECs combined with NSCLCs harbored previously reported driver gene alterations, all of which were shared between the two components. The median concordance rate of candidate somatic mutations between the two components was 71% (range, 60%-100%).

CONCLUSIONS

LCNECs have a similar genomic profile to SCLC, including promising therapeutic targets, such as the PI3K/AKT/mTOR pathway and other gene alterations. Sequencing-based molecular profiling is warranted in LCNEC for targeted therapies. Clin Cancer Res; 23(3); 757-65. ©2016 AACR.