Cancer predisposing germline mutations in patients (pts) with urothelial cancer (UC) of the renal pelvis (R-P), ureter (U) and bladder (B).

Abstract

4510 Background: Urothelial cancers (UC) are suspected to have a substantial hereditary component, but other than highly penetrant genes such as those in mismatch-repair pathway (e.g. MSH2) typically associated with R-P/U primaries, heritable gene mutations have not been systematically studied. We sought to investigate the prevalence of known cancer pre-disposing germline mutations in pts with UC originating from all sites within the urinary tract. Methods: Pts with R-P, U and B primaries, unselected for suspicion of inherited cancer syndrome, were prospectively enrolled from medical oncology and urology clinics to a germline sequencing protocol from June 2016 to January 2017. Germline gene analysis was performed in a CLIA-certified lab using a next generation sequencing (NGS) platform (MSK-IMPACT) that analyzes tumor-normal DNA pairs. The germline gene panel consisted of 76 genes associated with hereditary cancer predisposition. Results: As of January 24, 2017, 101 pts have NGS results available, with median age 63 (31-87), 76% male, 24% female. Primary sites were B (67%), R-P/U (31%), or both (3%). 73% had organ-confined disease and 27% had metastases. 8% had early onset (≤45 yrs at diagnosis), 10% had a family history of UC, 25% had documented non-UC cancers. 25 pathogenic or likely pathogenic (P-LP) mutations were identified in 22 patients. P-LP mutations were present in 29% of pts with R-P/U primaries and 18% of pts with B primaries. 12 DNA damage response gene alterations were found (4 CHEK2, 3 BRCA1, 2 BRCA2, 1 ATM, 1 BRIP1, 1 NBN) and 8 in Lynch syndrome associated genes (5 MSH2, 2 MSH6, 1 MLH1). Other mutations include 2 APC, 1 TP53, and 1 FH. Notably 3 pts had 2 alterations each ( MSH6/ APC, BRCA2/ APC, BRCA1/ CHEK2). 9/22 pts with P-LP mutations did not meet American College of Medical Genetics criteria for genetic screening. Conclusions: 22% of UC pts had a germline mutation in a cancer-associated gene. There was an unexpectedly high frequency of pts with DNA-repair pathway mutations. Active accrual is ongoing to define the full spectrum of alterations. These results have profound implications for genetic counseling and screening and further studies are warranted.