Abstract 5685: An evaluation of DNA and RNA based blood biomarkers in prostate cancer
Authors: Antonello Jenny , Chudziak Jakub , Redfern Alan , Foy Victoria , Srivastava Shambhavi , Syed Adnan , Burt Deborah , Ayub Mahmood , Kilerci Bedirhan , Parry Marina , Marais Richard , Baena Esther , Miller Crispin , Rothwell Dominic , Clarke Noel , Dive Caroline , Brady Ged 
Published: July 2017

Background: Prostate cancer (CaP) is the second-leading cause of male cancer-related mortality in Western societies. Localised prostate cancer (Loc-CaP) can be classified into low-, intermediate-, or high-risk groups. Active surveillance is recommended for low-risk patients, whereas radiotherapy or surgery is often indicated in intermediate- and high-risk patients, with possible intensification using hormone therapy treatment. Despite advances in radiation delivery and surgery, ~20% of patients will not be cured with local treatment and require androgen deprivation therapy (ADT). The majority will develop resistance to ADT resulting in castration resistant prostate cancer (CRPC) with poor prognosis and increased risk of metastatic disease (mCRPC). Biomarkers are being developed based on tumour biopsies which may help stratify patients and allow more effective treatment. However tumour biopsies are invasive, demanding for patients and surgeons as well as challenging for longitudinal sampling. Here we evaluate a range of blood biomarkers suitable for longitudinal sampling including circulating tumour cells (CTCs), circulating tumour DNA (ctDNA) and Tumour educated platelet mRNA (TEP-RNA).

Methods: A blood sampling, processing and banking pipeline has been established for CaP patients providing ctDNA, enriched and single CTCs as well as TEP-RNA. Following ctDNA isolation, next generation sequencing (NGS) libraries are prepared to generate copy number alteration (CNA) data and mutation profiles. CTCs are enriched using both the epitope independent Parsortix (P-CTC) (Chudziak J. et al, 2016) and the epitope dependent (EPCAM and KRT19) CellSearch (CS-CTC) platforms. Genomic analysis of CTCs is carried out by NGS of whole genome amplified (WGA) single and pooled CTCs. CTC and TEP-RNA mRNA profiles are established using both the Fluidigm RT qPCR (Fluidigm Biomark™ HD system) and RNA-Seq.

Results: Over 160 Loc-CaP and 100 mCRPC blood samples have been collected, processed and banked. In keeping with published data 53% of the 100 mCRPC patients have &gt5 CS-CTCs (a poor prognostic indicator) compared to 100% of Loc-CaP having &lt;2 CTCs. Control cell “spike in” RNA data showed =&gt;1000 fold enrichment of epithelial mRNAs post Parsortix CTC enrichment indicate an equivalent enrichment of the “spiked in” cells. Similar epithelial mRNA enrichment was seen in 3/5 mCRPC clinical samples tested. Tumour associated CNA changes were clearly detected in at least 15 of the 1st 22 mCRPC ctDNA samples. Sample processing and statistical analysis is ongoing to evaluate if these blood biomarkers, either alone or in combination, can be linked to clinical status or outcome.

Note: This abstract was not presented at the meeting.

Citation Format: Jenny Antonello, Jakub Chudziak, Alan Redfern, Victoria Foy, Shambhavi Srivastava, Adnan Syed, Deborah Burt, Mahmood Ayub, Bedirhan Kilerci, Marina Parry, Richard Marais, Esther Baena, Crispin Miller, Dominic Rothwell, Noel Clarke, Caroline Dive, Ged Brady. An evaluation of DNA and RNA based blood biomarkers in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5685. doi:10.1158/1538-7445.AM2017-5685