Detection of Novel NRG1, EGFR, and MET Fusions in Lung Adenocarcinomas in the Chinese Population

Introduction: Multiple oncogene fusions beyond ALK receptor tyrosine kinase (ALK), RET, and ROS1 fusion has been described in lung cancer, especially in lung adenocarcinomas without common oncogenic mutations. Molecular inhibitors have been developed and proved effective for patients whose tumors harbor these novel alterations.

Methods: A consecutive series of surgically resected lung adenocarcinomas were collected and profiled using an enrichment strategy to detect nine common oncogenic driver mutations and fusions concerning EGFR, KRAS, HER2, BRAF, MET, ALK, RET, ROS1, and FGFR. Driver-negative cases were further analyzed by a comprehensive RNA-based next-generation sequencing (NGS) fusion assay for novel fusions.

Results: In total, we profiled 1681 lung adenocarcinomas, among which 255 cases were common driver-negative. One hundred seventy-seven cases had sufficient tissue for NGS fusions screening, which identified eight novel fusions. NRG1 fusions occurred in 0.36% of all lung adenocarcinoma cases (6 of 1681 cases), including 4 CD74-NRG1-positive cases, 1 RBPMS-NRG1-positive case, and 1 novel ITGB1-NRG1-positive case. Furthermore, another 2 novel fusions were also detected, including 1 EGFR-SHC1 fusion and 1 CD47-MET fusion, both of which were in-frame and retained the functional domain of the corresponding kinases. No fusion event was detected for NTRK, KRAS, BRAF or HER2 genes in this cohort. Detailed clinicopathologic data showed that invasive mucous adenocarcinoma (three of eight cases) and acinar-predominant adenocarcinoma (three of eight cases) were the most prevalent pathologic subtypes among novel fusions.

Conclusions: Fusions affecting NRG1, EGFR, and MET were detected in 0.48% of unselected lung adenocarcinomas, and NRG1 fusions ranked the most prevalent fusions in common driver-negative lung adenocarcinomas from Chinese population. RNA-based NGS fusion assay was an optional method for screening actionable fusions in common driver-negative cases.