Genetic alteration profiling of Chinese lung adenocarcinoma: A targeted and immunotherapy biomarker analysis.

Abstract

e20572 Background: Lung adenocarcinoma is the most common primary lung cancer, comprises about 30% of lung cancers. So far, little is known about an in-depth molecular characterization for lung adenocarcinoma in Chinese patients. The genomic characteristics, microsatellite instability (MSI) status, programmed cell death-1 (PD-L1) and tissue tumor mutational burden (tTMB) in Chinese lung adenocarcinoma patients will benefit to understanding drug resistance-related mechanisms. Methods: 591 Formalin-Fixed Paraffin-Embedded (FFPE) lung adenocarcinoma samples were collected and detected by Next Generation Sequencing 603-gene panel. The biomarkers of immunotherapy (TMB-High [≥10/Mb], MSI-High, and PD-L1 22C3 [TPS] were also calculated. Results: Of 591 patients, 312 patients (52.8%) were male and 279 (47.2%) patients were female. The median age of the patients was 60.7 (range 28-99). The most commonly mutated genes were EGFR (45.5%), TP53 (22.1%), KRAS (7.8%), PIK3CA (5.3%), ERBB2 (2.5%), BRAF (2.2%), CTNNB1 (1.5%), SMAD4 (1.5%),NRAS (1.0%), SMAD4 (1.5%), NRAS (1%), ATM (1%), RB1 (1%), NF1(1%), IDH2 (0.67%). Three genes mutations (EGFR, TP53, KRAS) were identified significantly different between male and female. EGFRmutations were significantly more frequent in females (54.12%) than in males (37.5%;p = 0.000051). In contrast, TP53 mutations were significantly more frequent in males (11.53%) than in females. KRASmutations were significantly more frequent in males (25.6%) than in females (17.9%;p = 0.023). (3.6%;p = 0.0003). The aging of patients was associated with a higher PTEN mutations (< 50 years-old, p = 0.039), RAF1 mutations (> 76 years-old, p = 0.038), BRCA1 mutations (< 42 years-old, p = 0.032). The average of TMB was 5.3 mut/Mb (range 0-54.8). Immunotherapy markers were presented in 36.4% of cases (TMB-High in 15.91%, PD-L1+(TPS > 1%) in 47.12%,PD-L1+(TPS > 50%) in 5.17%, MSI-High in 0.17%). PD-L1 expression and TMB score were not significantly correlated in lung adenocarcinoma. The TMB score was associated with a higher TP53 mutations(TMB > 6.6, p < 0.0001), KRAS(TMB > 6.1, p = 0.034), NF1(TMB > 9.8, p = 0.0018), IDH2(TMB > 11.3, p = 0.0028). Conclusions: These findings may be helpful for identifying therapeutic targets strategies in lung adenocarcinoma patients that were previously unavailable to clinicians in China.