Targeted sequencing reveals distinct pathogenic variants in Chinese patients with lung adenocarcinoma brain metastases.

Lung cancer is the most common type of malignancy to metastasize to the brain, with the median survival time of patients being 6-11 months. In the present study, the aim was to compare the actionable gene mutation profiles of primary lung adenocarcinoma (LC) samples and LC brain metastasis (LCBM) samples through targeted sequencing. Next generation sequencing (NGS) of 13 formalin-fixed, paraffin-embedded LC samples and 15 LCBM samples was performed using a customized OncoAim™ cancer panel and OncoAim™ RNA fusion panel on the MiSeq platform. The OncoAim™ cancer panel pipeline and OncoAim™ RNA fusion panel pipeline were used for bioinformatic analysis. Together, 43 variants were observed in 7 genes from the 28 cancer samples. The mutated genes of LCBM were tumor protein (TP)53, epidermal growth factor receptor (EGFR), catenin β1, phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α, mothers against decapentaplegic homolog 4, Kirsten rat sarcoma viral oncogene homolog (KRAS) and proto-oncogene B-Raf, which were exhibited in 10/15 (66.7%), 6/15 (40.0%), 3/15 (20.0%), 2/15 (13.3%), 2/15 (13.3%), 1/15 (6.7%) and 1/15 (6.7%) of samples, respectively. The mutated genes of LC were TP53, EGFR and KRAS, which were exhibited in 11/13 (84.6%), 5/13 (38.5%) and 2/13 (18.2%) of samples, respectively. echinoderm microtubule associated protein like 4-anaplastic lymphoma kinase rearrangements were present in 1 LCBM sample. For 2 LC samples and 1 LCBM sample, no genetic alterations were observed. The NGS data also revealed a novel 4-codon deletion of TP53 (p.V166_H169del) and a novel TP53 splice site mutation (7577157-63del TACTCAG). Further potentially actionable mutations were detected in LCBM, indicating a high degree of genetic heterogeneity between the LC and LCBM samples that were analyzed. The present study demonstrated that NGS provides an improved approach for the discovery of potentially actionable mutations and the understanding of the mechanisms underlying tumor progression and evolution.