Circulating tumour-derived KRAS mutations in pancreatic cancer cases are predominantly carried by very short fragments of cell-free DNA

Autoři	ZVEREVA Maria ROBERTI Gabriel DURAND Geoffroy VOEGELE Catherine NGUYEN Minh Dao Nguyen DELHOMME Tiffany M. CHOPARD Priscilia FABIANOVA Eleonora ADAMCAKOVA Zora HOLCATOVA Ivana FORETOVÁ Lenka JANOUT Vladimir BRENNAN Paul FOLL Matthieu BYRNES Graham B. MCKAY James D. SCELO Ghislaine LE CALVEZ-KELM Florence
Rok publikování	2020
Druh	Článek v odborném periodiku
Časopis / Zdroj	EBioMedicine
Fakulta / Pracoviště MU	Lékařská fakulta
Citace
www	https://www.sciencedirect.com/science/article/pii/S2352396419306462?via%3Dihub
Doi	http://dx.doi.org/10.1016/j.ebiom.2019.09.042
Klíčová slova	Cell-free DNA; KRAS mutations; Plasma; Pancreatic cancer detection
Popis	Background: The DNA released into the bloodstream by malignant tumours called circulating tumour DNA (ctDNA), is often a small fraction of total cell-free DNA shed predominantly by hematopoietic cells and is therefore challenging to detect. Understanding the biological properties of ctDNA is key to the investigation of its clinical relevance as a non-invasive marker for cancer detection and monitoring. Methods: We selected 40 plasma DNA samples of pancreatic cancer cases previously reported to carry a KRAS mutation at the 'hotspot' codon 12 and re-screened the cell-free DNA using a 4-size amplicons strategy (57 bp, 79 bp, 167 bp and 218 bp) combined with ultra-deep sequencing in order to investigate whether amplicon lengths could impact on the capacity of detection of ctDNA, which in turn could provide inference of ctDNA and non-malignant cell-free DNA size distribution. Findings: Higher KRAS amplicon size (167 bp and 218 bp) was associated with lower detectable cell-free DNA mutant allelic fractions (p < 0.0001), with up to 4.6-fold (95% CI: 2.6-8.1) difference on average when comparing the 218bp- and the 57bp-amplicons. The proportion of cases with detectable KRAS mutations was also hampered with increased amplicon lengths, with only half of the cases having detectable ctDNA using the 218 bp assay relative to those detected with amplicons less than 80 bp. Interpretation: Tumour-derived mutations are carried by shorter cell-free DNA fragments than fragments of wild-type allele. Targeting short amplicons increases the sensitivity of cell-free DNA assays for pancreatic cancer and should be taken into account for optimized assay design and for evaluating their clinical performance. (C) 2019 Published by Elsevier B.V.