EGFR mutation testing on plasma and urine samples: A pilot study evaluating the value of liquid biopsy in lung cancer diagnosis and management.

BACKGROUND: Cell free DNA (cfDNA) shed by cancer cells into blood and body fluids is a potential substrate for molecular testing. While plasma is approved for EGFR mutation testing in certain clinical settings, mutation testing on urine is not well explored in lung cancer. In this study, we assess the feasibility and diagnostic accuracy of EGFR mutation analysis on plasma and urine samples. METHODS: Matched plasma and urine were collected prospectively from TKI-naïve lung adenocarcinoma (ADCA) patients (Group A) with available tumor tissue. Only plasma was collected from TKI-treated, known EGFR mutant ADCA patients developing TKI resistance (Group B). qPCR (tumor tissue) or digital droplet-PCR (urine/plasma) was performed for exon 19 deletions, exon 21 L858R and exon 20 T790M. RESULTS: Eighty-one patients (60 Group A, 21 Group B) were included. In Group A, EGFR mutations were detected in tissue in 34/60 (57%) patients. Mutations were detected in matched plasma in 24 (24/34, 70.5% sensitivity), and in matched urine in 15 (15/25, 60% sensitivity) of the 34 EGFR mutant cases, with no false positives (100% positive predictive value). Plasma and urine mutation results showed moderate agreement (70%) with a combined sensitivity of 88% (22/25). In Group B, new T790M mutations were detected in plasma in 61% (13/21) patients. CONCLUSION: Liquid biopsies show moderate sensitivity (plasma > urine) with 100% positive predictive rates for EGFR mutations. Testing of more than one type of liquid biopsy sample increases sensitivity. In TKI-resistant settings, liquid biopsies can obviate need for invasive biopsies in >60% patients.

LC-MS/MS-Based Quantitative Proteomics Analysis of Different Stages of Non-Small-Cell Lung Cancer.

Lung cancer has a higher incidence rate and mortality rate than all other cancers. Early diagnosis and treatment of lung cancer remain a major challenge, and the 5-year survival rate of its patients is only 15%. Basic and clinical research, especially the discovery of biomarkers, is crucial for improving the diagnosis and treatment of lung cancer patients. To identify novel biomarkers for lung cancer, we used the iTRAQ8-plex labeling technology combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to analyze the serum and urine of patients with different stages of lung adenocarcinoma and healthy individuals. A total of 441 proteins were identified in the serum, and 1,161 proteins were identified in the urine. The levels of elongation factor 1-alpha 2, proteasome subunit alpha type, and spermatogenesis-associated protein increased significantly in the serum of patients with lung cancer compared with those in healthy controls. The levels of transmembrane protein 143, cadherin 5, fibronectin 1, and collectin-11 decreased significantly in the serum of patients with metastases compared with those of nonmetastatic lung cancer patients. In the urine of stage III and IV lung cancer patients, the prostate-specific antigen and prostatic acid phosphatase decreased significantly, whereas neutrophil defensin 1 increased significantly. The results of LC-MS/MS were confirmed by enzyme-linked immunosorbent assay (ELISA) for transmembrane protein 143, cadherin 5, fibronectin 1, and collectin-11 in the serum. These proteins may be a potential early diagnosis and metastasis biomarkers for lung adenocarcinoma. Furthermore, the relative content of these markers in the serum and urine could be used to determine the progression of lung adenocarcinoma and achieve accurate staging and diagnosis.