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Assessment of common somatic mutations of EGFR, KRAS, BRAF, NRAS in pulmonary non-small cell carcinoma using iPLEX® HS, a new highly sensitive assay for the MassARRAY® System.

ABSTRACT: Increased early detection and personalized therapy for lung cancer have coincided with greater use of minimally invasive sampling techniques such as endobronchial ultrasound-guided biopsy (EBUS), endoscopic ultrasound-guided biopsy (EUS), and navigational biopsy, as well as thin needle core biopsies. As many lung cancer patients have late stage disease and other comorbidities that make open surgical procedures hazardous, the least invasive biopsy technique with the highest potential specimen yield is now the preferred first diagnostic study. However, use of these less invasive procedures generates significant analytical challenges for the laboratory, such as a requirement for robust detection of low level somatic mutations, particularly when the starting sample is very small or demonstrates few intact tumor cells. In this study, we assessed 179 clinical cases of non-small cell lung carcinoma (NSCLC) that had been previously tested for EGFR, KRAS, NRAS, and BRAF mutations using a novel multiplexed analytic approach that reduces wild-type signal and allows for detection of low mutation load approaching 1%, iPLEX® HS panel for the MassARRAY® System (Agena Bioscience, San Diego, CA). This highly sensitive system identified approximately 10% more KRAS, NRAS, EGFR and BRAF mutations than were detected by the original test platform, which had a sensitivity range of 5-10% variant allele frequency (VAF).

SUBMITTER: Sutton BC

PROVIDER: S-EPMC5604939 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundRecent advances in molecular genetics have enabled to determine the genetic causes of non-syndromic hearing loss, and more than 100 genes have been related to the phenotype. Due to this extraordinary genetic heterogeneity, a large percentage of patients remain without any molecular diagnosis. This condition imply the need for new methodological strategies in order to detect a greater number of mutations in multiple genes. In this work, we optimized and tested a panel of 86 mutations in 17 different genes screened using a high-throughput genotyping technology to determine the molecular etiology of hearing loss.MethodsThe technology used in this work was the MassARRAY iPLEX® platform. This technology uses silicon chips and DNA amplification products for accurate genotyping by mass spectrometry of previous reported mutations. The generated results were validated using conventional techniques, as direct sequencing, multiplex PCR and RFLP-PCR.ResultsAn initial genotyping of control subjects, showed failures in 20 % of the selected alterations. To optimize these results, the failed tests were re-designed and new primers were synthesized. Then, the specificity and sensitivity of the panel demonstrated values above 97 %. Additionally, a group of 180 individuals with NSHL without a molecular diagnosis was screened to test the diagnostic value of our panel, and mutations were identified in 30 % of the cases. In 20 % of the individuals, it was possible to explain the etiology of the HL. Mutations in GJB2 gene were the most prevalent, followed by other mutations in in SLC26A4, CDH23, MT-RNR1, MYO15A, and OTOF genes.ConclusionsThe MassARRAY technology has the potential for high-throughput identification of genetic variations. However, we demonstrated that optimization is required to increase the genotyping success and accuracy. The developed panel proved to be efficient and cost-effective, being suitable for applications involving the molecular diagnosis of hearing loss.

Project description:In recent years, the incidence of non?small cell lung cancer (NSCLC) has become the highest lethal rate of cancer worldwide. Molecular assays of EGFR, KRAS, BRAF, NRAS, PIK3CA and Her?2 are widely used to guide individualized treatment in NSCLC patients. Somatic mutations in 112 NSCLC patients, including 7 oncogenic driver genes, were detected by Iontorrent personal genome machine (PGM). Sanger sequencing was used to test and verify the results of PGM. Apart from uncommon mutations of EGFR, 101 NSCLC specimens were tested by droplet digital PCR (ddPCR). According to NGS results, mutations were detected in EGFR (58/112, 51.79% of tumors), KRAS (10/112, 8.93%), BRAF (2/112, 1.79%), NRAS (2/112, 1.79%), Her?2 (2/112, 1.79%), PIK3CA (6/112, 5.36%) and TP53 (31/112, 27.69%). There were 27 samples without any somatic mutations in all genes while 24 samples harboured mutations in two or more genes. A total of 61 samples had one or more mutations in a single gene. All alterations of 7 genes were presented and the overall detection rate of NGS and Sanger sequencing was determined to be 51.79% (58/112) and 37.50% (42/112), respectively (?2=5.88, P=0.015). Compared with Sanger sequencing, the total sensitivity and specificity of NGS assays was 95.24% (40/42) and 77.14% (54/70), respectively. The overall detection rate of NGS and ddPCR was 45.54% (46/101) and 47.52% (48/101), respectively (?2=0.000598, P=0.98). Compared with ddPCR, the overall sensitivity and specificity of NGS assays was 95.83% (46/48) and 98.11% (52/53), respectively. The findings indicated that the positive mutation rate of EGFR tested by NGS was significantly lower than that by Sanger sequencing, but the difference between ddPCR and NGS was not statistically significant. The high degree of agreement of reportable variants is proposed in both NGS and ddPCR analysis, suggesting the performance of NGS assays in routine clinical detection may be useful in determining the treatment decisions in NSCLC patients.

Dataset Information

Assessment of common somatic mutations of EGFR, KRAS, BRAF, NRAS in pulmonary non-small cell carcinoma using iPLEX® HS, a new highly sensitive assay for the MassARRAY® System.

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