Abstract A02: Detection of circulating cell-free DNA in renal cancer using renal cancer-specific DNA mutations and methylation changes

Abstract

Abstract Renal cell cancer (RCC) is the most deadly of urologic malignancies. It is a very invasive and chemoresistant disease that is often treated by surgical resection as it also responds poorly to radiotherapy. Importantly, more than 30% of RCCs recur or metastasize following treatment and in the cases believed to be curable by nephrectomy, distant metastasis can develop even 10 years post-surgery. There is therefore a significant focus on tissue-based biomarkers from the primary kidney tumors to help predict which patients are likely to recur, though there are no biomarkers used in routine clinical practice. Over recent years, much research has aimed at the utilization of blood-based biomarkers, mainly circulating cell-free DNA (cfDNA), as a method of noninvasive disease diagnosis and monitoring. cfDNA is detected through the identification of tumor-specific cfDNA mutations, although cfDNA methylation may be a more specific biomarker as many CpG sites can be tested in parallel. We have collected tumor tissue and pre- and post-surgery blood samples from renal cancer patients and generated exome sequencing and EPIC array data of 20 tumors with matched blood samples to detect tumor-specific DNA mutations and methylation patterns. We have identified well-known driver mutations in renal cancer in VHL in 11 tumors at 0.12-0.51 variant allele fraction (VAF); PBRM1 in 8 tumors at 0.12-0.45 VAF; BAP-1 in 2 tumors at 0.45 and 0.3 VAF; and SETD2 at 0.39 VAF; KDM5C at 0.27 VAF, and CTNNA2 at 0.2 VAF in one out of 20 patients. We aim to validate these changes using droplet digital PCR (ddPCR) in tumor and circulating tumor DNA (ctDNA) pre- and post-surgery. We next plan to combine the result of the exome sequencing with EPIC array data as well in house-developed cfDNA profiles based on publicly available tissue and individual cell type DNA methylation data. This approach will allow us to select the best mutation and methylation diagnostic and prognostic markers to aid the monitoring of early disease and relapse as well as the treatment of renal cell cancer. Citation Format: Martyna J. Adamowicz, John Thomson, Sophie J. Warlow, Utsa Patra, Helen Thain, Sophie Marion de Proce, Alexander Laird, Timothy J. Aitman. Detection of circulating cell-free DNA in renal cancer using renal cancer-specific DNA mutations and methylation changes [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr A02.