P1.02-063 Mutation Profiling by Targeted Next-Generation Sequencing of an Unselected NSCLC Cohort

Abstract

Non-small cell lung cancer (NSCLC) is a heterogeneous disease, with a wide diversity when it comes to molecular variations. In the non-squamous subset a large variety of altered driver genes have been identified. The mutational status was evaluated in a consecutive Swedish NSCLC cohort consisting of 354 patients, who underwent surgical resection between 2006 and 2010. DNA was prepared from either fresh frozen or formalin fixed paraffin embedded tissue (FFPE) and used for library preparation using a Haloplex gene panel and subsequently sequenced on an Illumina Hiseq instrument. The gene panel covers all exons of 82 genes, previously identified in NSCLC. The panel design utilizes two strand capture and reduced target fragment length compatible with degraded FFPE samples (Moens et al., J Mol Diagn, 2015). All previously known hotspot alterations in the driver genes KRAS, EGFR, HER2 (exon 20 insertions), NRAS, BRAF, MET (exon 14-skipping) and PIK3CA (exon 9 and 20) were analyzed in the 252 non-squamous cases, see figure. KRAS mutations were found in 98 patients (39%) whereas EGFR alterations were present in 33 (13%). The prevalence of KRAS mutations is higher than normally reported and could be due to the large fraction of smokers included in this cohort. The EGFR prevalence is a bit higher than previously demonstrated (Sandelin et al. Anitcancer Res, 2015). Mutations in the other driver genes were detected at low frequencies (HER2(3%), BRAF(2%), NRAS(1%), MET(1%) and PIK3CA(1%)). The preliminary analysis of mutational status in this large unselected Swedish NSCLC cohort reveals mutation frequencies in the common driver genes resembling previous reports on western populations with a high smoking rate. Ongoing analysis of the remaining genes will be used for pathway analysis and could provide a more complete picture of the lung cancer pathogenesis.