PD56-03 DETECTION OF PRIVATE CLONAL MUTATIONS IN LOCALISED PROSTATE CANCER FROM RARE MOLECULES OF CIRCULATING TUMOUR DNA

Abstract

You have accessJournal of UrologyProstate Cancer: Markers II1 Apr 2018PD56-03 DETECTION OF PRIVATE CLONAL MUTATIONS IN LOCALISED PROSTATE CANCER FROM RARE MOLECULES OF CIRCULATING TUMOUR DNA Keval Patel, Charlie Massie, Francesco Marass, James Morris, Andy Lynch, Florent Mouliere, David Neal, Vincent Gnanapragasam, Tim Forshew, and Nitzan Rosenfeld Keval PatelKeval Patel More articles by this author , Charlie MassieCharlie Massie More articles by this author , Francesco MarassFrancesco Marass More articles by this author , James MorrisJames Morris More articles by this author , Andy LynchAndy Lynch More articles by this author , Florent MouliereFlorent Mouliere More articles by this author , David NealDavid Neal More articles by this author , Vincent GnanapragasamVincent Gnanapragasam More articles by this author , Tim ForshewTim Forshew More articles by this author , and Nitzan RosenfeldNitzan Rosenfeld More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.2635AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Prostate cancer (PCa) is the most common solid tumour in men. Current methods of distinguishing between indolent and aggressive PCa can be inaccurate due to PCa heterogeneity and multi-focality. To compensate, many centres now take upwards of 20 biopsies of the prostate in one sitting, and monitor men with further biopsies to ensure that the disease is not progressing. There is therefore a need for a non-invasive biomarker than can monitor tumour heterogeneity and aggression. Circulating-tumour DNA (ctDNA) represents an exciting opportunity to monitor cancer status non-invasively. We developed a method for analysis of multiple genomic regions whilst retaining sensitivity for detection of individual mutant molecules, using multiplex replicate dilution sequencing, or MRD-Seq. METHODS MRD-Seq distributes a DNA sample into multiple replicate PCR reactions, where each reaction contains a small number of initial template molecules. As a result, the detection of a single mutant molecule generates a signal that is clearly discernible above the background noise. Dilutions series determined the limit of detection (0.09% AF) and background noise (0.02%AF). To assess ctDNA detection in the context of intra-tumoural heterogeneity, prostatectomy specimens and pre-operative plasma was obtained from 2 men with localised but multifocal PCa, with appropriate ethical approval (MREC:01/4/061). Whole genome sequencing of spatially 5-7 distinct regions of prostate cancer for each man was used to design probes to interrogate private mutations. RESULTS Plasma MRD-Seq demonstrated a mutant AF of 0.9% and 0.4% in the 2 men from ~1,000 genomic equivalent copies input. MRD-Seq detected the presence of private mutations from multiple private clones in the plasma, with evidence that more aggressive tumour regions (according to Gleason Grade) were over-represented in the plasma. CONCLUSIONS This proof of principle study suggests that ctDNA is detectable in the plasma of localised PCa patients and could be used to monitor men on active surveillance and identify aggressive changes at an early stage. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e1062-e1063 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Keval Patel More articles by this author Charlie Massie More articles by this author Francesco Marass More articles by this author James Morris More articles by this author Andy Lynch More articles by this author Florent Mouliere More articles by this author David Neal More articles by this author Vincent Gnanapragasam More articles by this author Tim Forshew More articles by this author Nitzan Rosenfeld More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...