SAT630 Analytical Validation Of A Telomerase Reverse Transcriptase (TERT) Promoter Mutation Assay
Authors: Iyer Priyanka , Dadu Ramona , Barque Anna , Cleslei Zanelli , Jiang Huimin , Walsh Sean , Zheng Xingyu , Hao Yangyang , Huang Jing , Klopper Joshua P , Kloos Richard T , Cabanillas Maria 
Published: October 2023

Abstract
Disclosure: P. Iyer: None. R. Dadu: Advisory Board Member; Self; Exelixis, Inc., Bayer, Inc. Research Investigator; Self; Merck, Exelixis, Inc., AstraZeneca. A. Barque: Employee; Self; Veracyte, Inc. Stock Owner; Self; Veracyte, Inc. Z. Cleslei: Employee; Self; Veracyte, Inc. Stock Owner; Self; Veracyte, Inc. H. Jiang: Employee; Self; Veracyte, Inc. Stock Owner; Self; Veracyte, Inc. S. Walsh: Employee; Self; Veracyte, Inc. Stock Owner; Self; Veracyte, Inc. X. Zheng: Employee; Self; Veracyte, Inc. Stock Owner; Self; Veracyte, Inc. Y. Hao: Employee; Self; Veracyte, Inc. Stock Owner; Self; Veracyte, Inc. J. Huang: Employee; Self; Veracyte, Inc. Stock Owner; Self; Veracyte, Inc. J.P. Klopper: Employee; Self; Veracyte, Inc. Stock Owner; Self; Veracyte, Inc. R.T. Kloos: Employee; Self; Veracyte, Inc. Stock Owner; Self; Veracyte, Inc. M. Cabanillas: Advisory Board Member; Self; Exelixis, Inc., Bayer, Inc. Consulting Fee; Self; Lilly USA, LLC, Bayer, Inc. Research Investigator; Self; Genentech, Inc., Merck.
TERT promoter mutations are relatively enriched in larger, aggressive thyroid cancers and these malignancies carry an independently decreased rate of disease free and disease specific survival when compared to thyroid cancers with wild type TERT promoter gene sequences. High quality analytical validation of a diagnostic test promotes confidence in the results which inform clinical decision making. TERT promoter mutation testing is now offered as a complement to Afirma Genomic Sequencing Classifier (GSC) testing in thyroid nodules that are not designated as molecularly benign. The Afirma TERT test was developed at Veracyte, Inc. based on the AmpliSeq-for-Illumina technology to detect TERT promoter variants C228T and C250T in genomic DNA (gDNA) extracted from patient thyroid fine needle aspirates (FNAs) sent for Afirma GSC testing, without any need for increased needle passes or sample volume. Herein, we describe the analytical performance of the Afirma TERT test. We examined the analytical sensitivity of the Afirma TERT test to varied input DNA amounts and the limit of detection (LOD) of variant allele frequency (VAF). We determined the negative percent agreement (NPA) and the positive percent agreement (PPA) of the Afirma TERT test against a reference primer pair. We also evaluated the analytical specificity from potential interfering substances such as RNA and blood gDNA. Further, the intra-run, inter-run and inter-laboratory reproducibility of the assay were examined. Analytical sensitivity analysis showed that the Afirma TERT test is tolerant to variation in DNA input amount (7-13 ng) and can detect expected positive TERT promoter variants down to 5% VAF LOD at 7ng DNA input with &gt; 95% sensitivity. Both NPA and PPA were 100% against the reference primer pair. Analytical specificity studies demonstrated that the Afirma TERT test remains accurate in presence of 20% RNA or 80% blood gDNA for an average patient sample that typically has 30% VAF. The Afirma TERT test results are highly reproducible across different operators, runs, reagent lots, and laboratories. The Afirma TERT test also demonstrated a 100% confirmation rate when compared with an external NGS-based reference assay executed in a non-Veracyte laboratory. The analytical robustness and reproducibility of the Afirma TERT test support its routine clinical use among thyroid nodules with indeterminate cytology that are Afirma GSC suspicious or Bethesda V/VI nodules.
Presentation: Saturday, June 17, 2023