Abstract: PD33-04
Sources of Funding: The Urology Foundation

Introduction

Personalised medicine strategies are increasingly reliant on DNA sequencing to stratify patients. Here we demonstrate the feasibility of using a cancer hot spot panel using targeted next-generation sequencing (NGS). In particular we concentrated on recurrent somatic mutations in cell signalling pathways or processes that can be clinically actionable or targeted by emerging therapies.

Methods

Formalin-fixed paraffin embedded (FFPE) primary prostate cancer samples were obtained from the Welsh Cancer Bank. Targeted-NGS was performed using the Life Technologies Ion Torrent: Ion AmpliSeq Cancer Hotspot Panel v2 and the Ion Personal Genome Machine sequencer. The hotspot panel covers ~2800 COSMIC mutations of 50 oncogenes and tumour suppressor genes. Standard IHC techniques were also used concentrating on markers of the Wnt, PI3-Kinase (PI3K) and MAP-Kinase (MAPK) oncogenic signalling pathways.

Results

61 primary prostate cancer samples were sequenced, 58 from radical retropubic prostatectomy (RRP) specimens and 3 from transurethral resection of prostate (TURP) sections, with a range of Gleason Scores (GS). _x000D_ _x000D_ 21/61 (34.4%) samples harboured a mutation in a cell cycle pathway gene such as TP53 or RB1 and 3/61 (4.9%) in a DNA repair gene such as ATM. 10/61 (16.5%) of samples harboured a mutation in a gene associated with the Wnt pathway such as APC or CTNNB1. 14/61 (23.0%) of samples analysed had a mutation in a gene commonly associated with the PI3K pathway such as PTEN or AKT1. 5/61 (8.2%) had a mutation in a gene associated with the MAPK pathway such as KRAS. _x000D_ _x000D_ IHC profiles were analysed on 317 prostate samples: 73 normal and 244 cancers. There was greater expression of markers associated with Wnt, PI3K and MAPK signalling pathways in prostate cancer samples when compared to normal samples. There was greater expression in high-risk GSs with some markers associated with biochemical recurrence following RRP. Furthermore, we were able to separate low- and high-risk GS samples based on molecular profiles using markers of the Wnt, PI3K and MAPK and principle components analysis._x000D_

Conclusions

Targeted NGS and IHC can identify recurrent mutations and signalling pathway aberrations within primary prostate cancer samples, which have potential to be targeted and used in routine clinical practice. In addition, the molecular signatures of low- and high-risk are different and can be separated using a combination of markers and IHC. This finding could explain the marked difference in the behaviours of these tumours types.

Funding

The Urology Foundation