Application of Whole-Genome Sequencing in Older Esophageal Carcinoma FFPE Tissues Reveals Novel Insights

13 Nov 2019, 11:00:00 Eastern Time (ET)

Collection of fresh-frozen tumor samples is often challenging or infeasible, leading many studies to rely on formalin-fixed, paraffin-embedded (FFPE) tumor tissue samples. Because these tissues are often paired with a great deal of clinical and outcome data, analysis of these archives has the potential to lead to major advances in cancer treatment and prevention.

Whole-genome sequencing (WGS) analysis of FFPE samples could enable novel insights from these vast archival sample collections; however, robust WGS of FFPE tissues has remained elusive due to poor yields of fragmented DNA, low complexity sequencing libraries, uneven genomic coverage and sequencing artifacts attributed to fixation.

To examine WGS of stored FFPE samples, the National Cancer Institute (NCI) analyzed 20 paired esophageal carcinoma samples (primary tumors and matched germline samples) that had been stored for 10-15 years using a proprietary extraction and library preparation methodology (WuXi NextCODE’s SeqPlus). The research team assessed SeqPlus’ performance on these older FFPE tissues and measured variant call concordance between WGS and a targeted, high-depth sequencing panel (269 genes, sequenced at >400x mean coverage). SeqPlus produced consistent coverage versus the targeted panel, which showed uneven coverage across the targeted genes.