Abstract 3539: Impact of formalin time on targeted NGS performance in FFPE tissue

Abstract

Abstract Targeted next generation sequencing (NGS) panel testing is now a standard of care for management of advanced stage cancer. At present, most targeted NGS oncology testing occurs with formalin fixed paraffin embedded (FFPE) tissue. This is due to the established utility and prevalence of FFPE in routine histologic classification, grading, staging, and ancillary testing. In addition, FFPE materials are an optimally suited medium for determining adequacy of the specimen prior to downstream NGS targeted panel testing. For these reasons, as well as a growing trend of minimally invasive procedures, clinical specimens are increasingly prioritized for FFPE to meet the bulk of standard oncology care. Currently, formalin fixation time guidelines do exist for specific immunohistochemical and in-situ hybridization oncology tests. However, specific FFPE processing guidelines have yet to be established that would optimize targeted NGS panel testing performance. In this study, our aim was to develop contrived FFPE materials using the FDA-led Sequencing Quality Control Phase II (SEQC2) consortium working group 2 (WG2) cell line materials. The overarching goal was to use these FFPE materials to identify an upper limit of formalin time associated with minimal impact on somatic variant calling performance in targeted NGS oncology panels. The SEQC2 - WG2 normal lymphoblast cell line was selected as a well-characterized test material to undergo systematic alteration in formalin fixation time (1, 2, 6 and 24 hours) prior to “routine” tissue processing and embedding (FFPE). These FFPE cell-block materials, derived from a single sample source (with both extracted FFPE DNA as well as shaved sections), were distributed to multiple labs running various targeted NGS amplicon and hybridization oncology panels. The expected outcome of these studies is to provide general guidance to the community on how formalin time in FFPE specimens impacts targeted NGS oncology panel testing performance. In addition, we hope to identify genomic regions (internal control regions) that serve as markers for the full range of formalin time FFPE-effect. This information will assist in improving the lower limit of detection for variant calling (<5% variant allele frequency). Citation Format: Thomas M. Blomquist, Erin Crawford, James Willey, Joshua Xu, Onco-panel Working Group of the Sequencing Quality Control Phase 2 (SEQC2) Consortium. Impact of formalin time on targeted NGS performance in FFPE tissue [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3539.