1572 Background: PLELC, a rare and distinct type of primary lung cancer, is characterized by Epstein-Barr virus (EBV) infection. Histologically, it resembles undifferentiated nasopharyngeal carcinomas (NPC). Only a few hundred cases have been reported since its discovery. Due to the extreme rareness, its genomic landscape remains elusive. Methods: Tissue samples of 27 PLELC patients (13 males and 14 females) with various stages (Ib to IV) were subjected to targeted sequencing using a panel consisting of 520 cancer-related genes, spanning 1.6Mb of human genome. Results: Collectively, we identified 184 somatic mutations spanning 109 genes, including 107 SNVs, 12 insertions or deletions (INDELs) and 65 copy-number amplifications (CNAs). Approximately, 50% of patients had CNAs. One patient had no mutation detected from this panel. Except for 2 patients, 1 with HER2 amplification and another with KRAS mutation, no other classic NSCLC driver genes were detected. The most frequently mutated genes were CCND1, TP53, DAXX and NF kBIA, occurring in 30%, 26%, 22% and 22% of patients, respectively. Interestingly, 78% (21/27) patients had mutations in epigenetic regulators. Of the 184 mutations identified, 51 occurred in epigenetics-related genes. Pathway analysis also revealed an enrichment of genes participating in chromatin remodeling and organization. Next, we compared the genomic profile of PLELC with lung adenocarcinoma and EBV positive NPC. The frequency of TP53 mutations was significantly higher in lung adenocarcinoma (68% vs 26%, p = 0.021). Comparing to NPC, PLELC had significantly more mutations in epigenetic regulators. TMB analysis revealed a median TMB of 1.6/Mb, significantly lowered than lung adenocarcinomas (p < 0.01). We also assessed PD-L1expression and revealed that 67% had an overexpression of PD-L1. Interestingly, TP53-mutant patients were more likely to associated low PD-L1 expression (p < 0.01). Conclusions: In this study, we elucidated a distinct genomic landscape associated with PLELC with no classic NSCLC driver mutation but an enrichment of mutations in epigenetic regulators. The observation of high expression of PD-L1 and lack of canonical druggable driver mutation raises the potential of immunocheckpoint blockade therapy for PLELC.
Genomic Landscape of Atypical Adenomatous Hyperplasia Reveals Divergent Modes to Lung Adenocarcinoma
