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Comparative Analysis of Two Methods for the Detection of EGFR Mutations in Plasma Circulating Tumor DNA from Lung Adenocarcinoma Patients.

ABSTRACT: Mutations in the epidermal growth factor receptor (EGFR) are associated with various solid tumors. This study aimed to compare two methods for the detection of EGFR mutations in circulating tumor DNA (ctDNA) from lung adenocarcinoma (LUAD) patients and to evaluate the clinical significance of EGFR mutations in ctDNA. In this prospective cohort study, the EGFR mutation status of 77 patients with stage IIIB or IV LUAD was first determined using lung cancer tissue. The amplification refractory mutation system (ARMS) and single allele base extension reaction combined with mass spectroscopy (SABER/MassARRAY) methods were also used to detect EGFR mutations in plasma ctDNA from these patients and then compared using the EGFR mutation status in lung cancer tissue as a standard. Furthermore, the relationship between the presence of EGFR mutations in ctDNA after receiving first-line EGFR-tyrosine kinase inhibitor (EGFR-TKI) therapy and survival was evaluated. The overall sensitivity and specificity for the detection of EGFR mutations in plasma ctDNA by ARMS and SABER/MassARRAY were 49.1% vs. 56% and 90% vs. 95%, respectively. The agreement level between these methods was very high, with a kappa-value of 0.88 (95% CI 0.77-0.99). Moreover, 43 of the patients who carried EGFR mutations also received first-line EGFR-TKI therapy. Notably, patients with EGFR mutations in plasma ctDNA had significantly shorter progression-free survival (9.0 months, 95% CI 7.0-11.8, vs. 15.0 months, 95% CI 11.7-28.2; p = 0.02) and overall survival (30.6 months, 95% CI 12.4-37.2, vs. 55.6 months, 95% CI 25.8-61.8; p = 0.03) compared to those without detectable EGFR mutations. The detection of EGFR mutations in plasma ctDNA is a promising, minimally invasive, and reliable alternative to tumor biopsy, and the presence of EGFR mutations in plasma ctDNA after first-line EGFR-TKI therapy is associated with poor prognosis.

SUBMITTER: Hung MS

PROVIDER: S-EPMC6627967 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundThe use of tyrosine kinase inhibitors to target the epidermal growth factor receptor gene (EGFR) in patients with non-small-cell lung cancer is effective but limited by the emergence of drug-resistance mutations. Molecular characterization of circulating tumor cells may provide a strategy for noninvasive serial monitoring of tumor genotypes during treatment.MethodsWe captured highly purified circulating tumor cells from the blood of patients with non-small-cell lung cancer using a microfluidic device containing microposts coated with antibodies against epithelial cells. We performed EGFR mutational analysis on DNA recovered from circulating tumor cells using allele-specific polymerase-chain-reaction amplification and compared the results with those from concurrently isolated free plasma DNA and from the original tumor-biopsy specimens.ResultsWe isolated circulating tumor cells from 27 patients with metastatic non-small-cell lung cancer (median number, 74 cells per milliliter). We identified the expected EGFR activating mutation in circulating tumor cells from 11 of 12 patients (92%) and in matched free plasma DNA from 4 of 12 patients (33%) (P=0.009). We detected the T790M mutation, which confers drug resistance, in circulating tumor cells collected from patients with EGFR mutations who had received tyrosine kinase inhibitors. When T790M was detectable in pretreatment tumor-biopsy specimens, the presence of the mutation correlated with reduced progression-free survival (7.7 months vs. 16.5 months, P<0.001). Serial analysis of circulating tumor cells showed that a reduction in the number of captured cells was associated with a radiographic tumor response; an increase in the number of cells was associated with tumor progression, with the emergence of additional EGFR mutations in some cases.ConclusionsMolecular analysis of circulating tumor cells from the blood of patients with lung cancer offers the possibility of monitoring changes in epithelial tumor genotypes during the course of treatment.

Project description:Epithelial growth factor receptor (EGFR)-tyrosine kinase inhibitors are the standard first-line treatment for patients with metastatic non-small cell lung cancer (NSCLC) expressing sensitive EGFR-mutants. Other drugs target different driver mutants, including the serine/threonine-protein kinase B-raf (BRAF) inhibitor dabrafenib, which has exhibited promising efficacy for treating patients with metastatic BRAF-mutated NSCLC. Therefore, identifying patients carrying mutations that may be treated using targeted therapies is important. However, the methods of molecular detection presently applied in clinical practice, particularly detection of BRAF in NSCLC patients, require further investigation. Therefore, more sensitive and economic methods are required. The present study applied the competitive allele-specific TaqMan polymerase chain reaction (CastPCR) technology to the molecular detection of EGFR (del2235-2249, del2236-2250, T790M, L858R) and BRAF (V600E, G469A, D594G) mutations in 144 treatment-naive patients with lung adenocarcinoma, and analyzed the association between the mutation rates and patients' clinicopathological features. 51.4% (74/144) cases were identified harboring EGFR mutations. A total of 40.3% (58/144) patients carried sensitizing mutations (exon 19 deletion or L858R) and 14.6% (21/144) carried T790M mutations. 6.9% (10/144) mutation-positive patients were double-mutated. Total EGFR mutation rate was significantly increased in female compared with that of males (60.9 vs. 43.8%, P<0.05), in non-smokers compared with that of smokers (62.8 vs. 34.5%, P<0.05). In total, 8.3% (12/144) patients were identified with BRAF mutations. 16.7% were V600E (2/12) and 83.3% (10/12) were non-V600E mutants. Among the 10 non-V600E mutations, D594G accounted for 90.0% (9/10) and G469A accounted for 10.0% (1/10). Statistical analysis demonstrated that the BRAF mutation rate was not associated with any of the following clinicopathological features: Sex, age, smoking history, clinical stages, distant metastasis, differentiation degree, tumor size and regional lymph node metastasis (P≥0.05). CastPCR technology is a robust method with high sensitivity for the molecular detection of EGFR and BRAF mutations in clinical formalin-fixed paraffin-embedded samples.

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Comparative Analysis of Two Methods for the Detection of EGFR Mutations in Plasma Circulating Tumor DNA from Lung Adenocarcinoma Patients.

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