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Performance characteristics of next-generation sequencing in clinical mutation detection of colorectal cancers.

ABSTRACT: Activating mutations in downstream genes of the epidermal growth factor receptor (EGFR) pathway may cause anti-EGFR resistance in patients with colorectal cancers. We present performance characteristics of a next-generation sequencing assay designed to detect such mutations. In this retrospective quality assessment study, we analyzed mutation detected in the KRAS, NRAS, BRAF, and PIK3CA genes by a clinically validated next-generation sequencing assay in 310 colorectal cancer specimens. Tumor cellularity and mutant allele frequency were analyzed to identify tumor heterogeneity and mutant allele-specific imbalance. Next-generation sequencing showed precise measurement of mutant allele frequencies and detected 23% of mutations with 2-20% mutant allele frequencies. Of the KRAS mutations detected, 17% were outside of codons 12 and 13. Among PIK3CA mutations, 48% were outside of codons 542, 545, and 1047. The percentage of tumors with predicted resistance to anti-EGFR therapy increased from 40% when testing for only mutations in KRAS exon 2 to 47% when testing for KRAS exons 2-4, 48% when testing for KRAS and NRAS exons 2-4, 58% when including BRAF codon 600 mutations, and 59% when adding PIK3CA exon 20 mutations. Right-sided colorectal cancers carried a higher risk of predicted anti-EGFR resistance. A concomitant KRAS mutation was detected in 51% of PIK3CA, 23% of NRAS, and 33% of kinase-impaired BRAF-mutated tumors. Lower than expected mutant allele frequency indicated tumor heterogeneity, while higher than expected mutant allele frequency indicated mutant allele-specific imbalance. Two paired neuroendocrine carcinomas and adjacent adenomas showed identical KRAS mutations, but only PIK3CA mutations in neuroendocrine carcinomas. Next-generation sequencing is a robust tool for mutation detection in clinical laboratories. It demonstrates high analytic sensitivity and broad reportable range, and it provides simultaneous detection of concomitant mutations and a quantitative measurement of mutant allele frequencies to predict tumor heterogeneity and mutant allele-specific imbalance.

SUBMITTER: Haley L

PROVIDER: S-EPMC4618462 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature

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Performance characteristics of next-generation sequencing in clinical mutation detection of colorectal cancers.

Haley Lisa L Tseng Li-Hui LH Zheng Gang G Dudley Jonathan J Anderson Derek A DA Azad Nilofer S NS Gocke Christopher D CD Eshleman James R JR Lin Ming-Tseh MT

Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 20150731 10

Activating mutations in downstream genes of the epidermal growth factor receptor (EGFR) pathway may cause anti-EGFR resistance in patients with colorectal cancers. We present performance characteristics of a next-generation sequencing assay designed to detect such mutations. In this retrospective quality assessment study, we analyzed mutation detected in the KRAS, NRAS, BRAF, and PIK3CA genes by a clinically validated next-generation sequencing assay in 310 colorectal cancer specimens. Tumor cel ...[more]

PMID: 26226847

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Project description:Short-read sequencing can provide detection of multiple genomic determinants of antimicrobial resistance from single bacterial genomes and metagenomic samples. Despite its increasing application in human, animal, and environmental microbiology, including human clinical trials, the performance of short-read Illumina sequencing for antimicrobial resistance gene (ARG) detection, including resistance-conferring single nucleotide polymorphisms (SNPs), has not been systematically characterized. Using paired-end 2 × 150 bp (base pair) Illumina sequencing and an assembly-based method for ARG prediction, we determined sensitivity, positive predictive value (PPV), and sequencing depths required for ARG detection in an Escherichia coli isolate of sequence type (ST) 38 spiked into a synthetic microbial community at varying abundances. Approximately 300,000 reads or 15× genome coverage was sufficient to detect ARGs in E. coli ST38, with comparable sensitivity and PPV to ~100× genome coverage. Using metagenome assembly of mixed microbial communities, ARG detection at E. coli relative abundances of 1% would require assembly of approximately 30 million reads to achieve 15× target coverage. The minimum sequencing depths were validated using public data sets of 948 E. coli genomes and 10 metagenomic rectal swab samples. A read-based approach using k-mer alignment (KMA) for ARG prediction did not substantially improve minimum sequencing depths for ARG detection compared to assembly of the E. coli ST38 genome or the combined metagenomic samples. Analysis of sequencing depths from recent studies assessing ARG content in metagenomic samples demonstrated that sequencing depths had a median estimated detection frequency of 84% (interquartile range: 30%-92%) for a relative abundance of 1%. IMPORTANCE Systematically determining Illumina sequencing performance characteristics for detection of ARGs in metagenomic samples is essential to inform study design and appraisal of human, animal, and environmental metagenomic antimicrobial resistance studies. In this study, we quantified the performance characteristics of ARG detection in E. coli genomes and metagenomes and established a benchmark of ~15× coverage for ARG detection for E. coli in metagenomes. We demonstrate that for low relative abundances, sequencing depths of ~30 million reads or more may be required for adequate sensitivity for many applications.

Dataset Information

Performance characteristics of next-generation sequencing in clinical mutation detection of colorectal cancers.

Publications

Performance characteristics of next-generation sequencing in clinical mutation detection of colorectal cancers.

Similar Datasets

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