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PurposeThe main objective of this study was to investigate the relationship among the clinical characteristics and the frequency of T790M mutation in advanced epidermal growth factor receptor (EGFR)‒mutant lung adenocarcinoma patients with acquired resistance after firstline EGFR‒tyrosine kinase inhibitor (TKI) treatment.Materials and MethodsWe enrolled EGFR-mutant stage IIIB-IV lung adenocarcinoma patients, who had progressed to prior EGFR-TKI therapy, and evaluated their rebiopsy EGFR mutation status.ResultsA total of 205 patients were enrolled for analysis. The overall T790M mutation rate of rebiopsy was 46.3%. The T790M mutation rates among patients with exon 19 deletion mutation, exon 21 L858R point mutation, and other mutations were 55.0%, 37.3%, and 27.3%, respectively. Baseline exon 19 deletion was associated with a significantly higher frequency of T790M mutation (adjusted odds ratio, 2.14; 95% confidence interval [CI], 1.20 to 3.83; p=0.010). In the exon 19 deletion subgroup, there was a greater prevalence of T790M mutation than other exon 19 deletion subtypes in patients with the Del E746-A750 mutation (61.6% vs. 40.6%; odds ratio, 2.35; 95% CI, 1.01 to 5.49; p=0.049). The progression-free survival (PFS) of first-line TKI treatment > 11 months was also associated with a higher T790M mutation rate (54.1% vs. 39.3%; adjusted odds ratio, 1.82; 95% CI, 1.02 to 3.25; p=0.044). Patients who underwent rebiopsy at metastatic sites had more chance to harbor T790M mutation (52.6% vs. 33.8%; adjusted odds ratio, 1.97; 95% CI, 1.06 to 3.67; p=0.032).ConclusionPFS of first-line EGFR-TKI, rebiopsy site, EGFR exon 19 deletion and its subtype Del E746-A750 mutation are associated with the frequency of T790M mutation.

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Changes in plasma EGFR mutation status can be successfully assessed using the peptide nucleic acid-zip nucleic acid polymerase chain reaction clamp method and can serve as an independent outcome predictor.

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Different growth kinetics occurring between the sensitive and T790M-containing cells may result in the repopulation of tumor cells over time. Little information has yet been uncovered on whether rebiopsy timing influences the T790M detection rate. We enrolled a total of 98 epidermal growth factor receptor (EGFR)-mutant lung adenocarcinoma patients, who had a history of acquired resistance to EGFR-tyrosine kinase inhibitor (TKI) and available rebiopsy tumor specimens for reassessment of EGFR mutations. Rebiopsy was performed at the time of first EGFR-TKI progression in 54 patients (55.1%); for the other 44 patients (44.9%), rebiopsy was done with an interval from first EGFR-TKI progression (median 470.5 days, range 46-1742 days). Our results indicated that rebiopsy timing did not influence the detection rate of T790M and that the mutation could be identified in patients with a long EGFR-TKI-free interval. For patients without suitable lesions for rebiopsy at the time of EGFR-TKI progression, an attempt to rebiopsy should be considered during the subsequent treatment courses.

RAGE (receptor for advanced glycation end-product) is thought to be associated with metastasis and poor prognosis of various types of cancer. However, RAGE is constitutively expressed in the normal lung and down-regulated in cancerous lung, while the opposite evidence shows that RAGE-mediated signaling contributes to the tumorigenesis of lung cancer. Therefore, the role of RAGE in lung cancer progression is still unclear to be further investigated. In this study, RAGE-overexpressed stable clones of human lung cancer A549 cells and two local lung adenocarcinoma cell lines CL1-0 and CL1-5 were utilized to verify the effect of RAGE on lung cancer cells while the in vivo xenograft animal model was further performed to evaluate the role of RAGE in the progression of lung cancer. The growth of A549 cells was inhibited by RAGE overexpression. p53-dependent p21 CIP1 expression contributed to RAGE-induced growth inhibition by suppressing CDK2 kinase activity and retinoblastoma protein (RB) phosphorylation in vitro. On the other hand, RAGE overexpression promoted migration, invasion, and mesenchymal features of lung adenocarcinoma cells through ERK signaling. Furthermore, an in vivo xenograft experiment indicated that RAGE promoted the metastasis of lung cancer cells with p21 CIP1 up-regulation, ERK activation, and the changes of EMT markers. Regarding to the involvement of tumor-associated macrophage (TAM) in the microenvironment, we monitored the expressions of TAM markers including CD68 and CD163 as well as angiogenesis marker CD31 in xenograft slice. The data showed that RAGE might induce the accumulation of TAM in lung cancer cells and further accelerate the in vivo tumor growth. In summary, our study provides evidence indicating the distinct in vitro and in vivo effects of RAGE and related mechanisms on tumor growth and metastasis, which shed light on the oncogenic role of RAGE in lung cancer.

Immunotherapy targeting the programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) pathway has emerged as an effective treatment for lung cancer patients. It is important to evaluate the practicality of PD-L1 testing in real-world practice. A total of 211 non-small cell lung cancer patients were enrolled to detect 5 driver mutations and PD-L1 status (22C3 and SP263 assays) and to evaluate the characteristics of PD-L1 expression and its predictive value of immunotherapy. The PD-L1 positive (≥1%) and strong positive (≥50%) rate by SP263 assay was 27.0% and 12.8%. The concordance rates between 2 PD-L1 assays while using 1%, 10%, 25%, and 50% positive tumor cells as the cutoffs were 76.8%, 81.5%, 90.5%, and 94.3%, respectively. Smokers and patients without known actionable driver mutation were more likely to present strong positive PD-L1 [adjusted hazard ratio, 5.00 (95% confidence interval-CI, 1.60-15.64); P=0.006 and 3.59 (95% CI, 1.25-10.33); P=0.018, respectively]. Higher levels of smoking were associated with higher PD-L1 expressions. None of the EGFR, ALK, HER2, or BRAF-mutant nonsmokers displayed strong positive PD-L1 expression by SP263 assay. Among patients undergoing PD-1 checkpoint inhibitors therapy, high PD-L1 expression by SP263 was associated with a longer progression-free survival [adjusted hazard ratio, 0.15 (95% CI, 0.03-0.71); P=0.017]. In conclusion, our results suggest that PD-L1 status remains an important predictor of immunotherapy efficacy. The concordance between 22C3 and SP263 assays was greater at a higher cutoff level of positivity. Patients without known actionable driver mutation, along with smokers, particularly those having high smoking pack-years, were more likely to have strong PD-L1 expression.