Genomic Profiling Of Nephrectomy And Metastatic Sites In Patients With Advanced Clear Cell Renal Cell Carcinoma (Rcc).

513Background: Novel biomarkers are required to accurately assess response in renal cancer. Genomic alterations (GAs) in samples from primary (nephrectomy) (N) as compared distant metastases (M) in clear cell RCC (ccRCC) may have clinical implications as well as mutations in circulating tumour DNA (ctDNA). Methods: 237 primary ccRCC nephrectomy specimens and 156 samples from distant metastases were assayed by hybrid capture based comprehensive genomic profiling (CGP) in the course of clinical care to identify GAs suggesting benefit from targeted therapy. Tumor mutation burden (TMB) was assessed as the number of somatic coding point mutations per megabase of targeted territory. Aditionally, 17 patient-specific assays were developed to quantify ctDNA allele fraction (AF) in plasma of mRCC patients. Results: 1263 GAs and 34 clinically relevant GA (CRGAs) were identified. Most common GA identified were VHL (74%/72%), PBRM1 (40%/51%), SETD2 (28%/26%) in N and m respectively (Table). Additionally, most common C...