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decision-making on an individual basis. amenable to personalized genomics, where the level and type of mutations in ctDNA would inform clinical plasma of patients with less advanced cancers. Nevertheless, once optimized, this ''liquid biopsy'' approach will be TAm-Seq will need to achieve a more sensitive detection limit (<2% allele frequency) to identify mutations in the large regions of ctDNA. Although this provides a new way to noninvasively identify gene mutations in our blood, Through several experiments, the authors were able to show that TAm-Seq is a viable method for sequencing exhibited a rise in frequency. for example, stabilized disease was associated with low allelic frequency, whereas patients at relapse −− its treatment parallel. Forshew and coauthors showed that levels of mutant alleles reflected the clinical course of the disease and ovarian cancer and one woman with breast cancer at different time points, tracking as many as 10 mutations in Finally, the TAm-Seq approach was used to sequence ctDNA in plasma samples collected from two women with that had not been detected 15 months prior in the tumor mass itself. EGFR also identified a de novo mutation in at allelic frequencies of 2% to 65%. In plasma samples from one patient, they TP53 were able to identify mutations in . In plasma obtained from 38 patients with high levels of ctDNA, the authors KRAS , and BRAF , EGFR , TP53 including . designed primers to amplify 5995 bases that covered select regions of cancer-related genes, et al Forshew carcinomas. the authors were able to identify low-level mutations in the plasma of patients with high-grade serous ovarian amplify and sequence large genomic regions from even single copies of ctDNA. By sequencing such large regions, can colleagues have risen to the occasion by developing a tagged-amplicon deep sequencing (TAm-Seq) method that cancer outcome. Looking for diagnostic answers in circulating DNA is a challenge, but Forshew, Murtaza, and patients, a small fraction is circulating tumor DNA (ctDNA). An even smaller number harbor mutations that affect Five liters of circulating blood contain millions of copies of the genome, broken into short fragments; in cancer Deep Sequencing Tumor DNA in Plasma