Germline variants in urothelial carcinoma: Analysis of pathogenic and likely pathogenic variants in 645 subjects

• Published in: Journal of clinical oncology Vol. 37; no. 15_suppl; p. 1528
• Main Authors: Abou Alaiwi, Sarah, Nassar, Amin, Mouw, Kent William, Kwiatkowski, David J., Choueiri, Toni K., Curran, Catherine, Van Allen, Eliezer Mendel, Esplin, Edward D., Yang, Shan, Garber, Judy Ellen, Rana, Huma Q., Sonpavde, Guru
• Format: Journal Article
• Language: English
• Published: 20.05.2019
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/JCO.2019.37.15_suppl.1528

Abstract only 1528 Background: While small studies have supported a genetic cancer predisposition among subjects with urothelial carcinoma (UC), systematic germline evaluation of this population is lacking. Here, we report the prevalence of germline variants among subjects with UC from multiple centers completing panel-based testing at a large, commercial laboratory. Methods: 1149 UC subjects underwent germline testing of 1 to 126 genes using massively parallel sequencing with customized capture bait-sets to analyze exonic regions, flanking intronic sequences, and copy number alterations. Pathogenic (P) and likely pathogenic (LP) were confirmed using orthogonal technology in accordance with Invitae standard operating practices. Analysis was limited to 645 subjects who completed testing of a shared set of 42 genes. P/LP variants including single nucleotide variants/indels/ copy number variants are reported. De-identified personal and family cancer histories were evaluated. Fisher’s Exact test and the Mann-Whitney test were used to analyze categorical and continuous variables respectively. Results: Among the 645 UC subjects with 42-gene testing for any indication, median age at testing was 60 years (6-88) and 326 (51%) were female. P/LP variants were identified in 21 (50%) of the 42 genes in 98 (15%) of subjects, including Lynch syndrome genes (n = 26 [4%]), BRCA1/2 (n = 16 [2.5%]), CHEK2 (n = 15 [2.3%]), and heterozygous MUTYH (n = 12 [1.9%]). Among 18 DNA damage repair (DDR) genes assessed, 90 P/LP variants were detected in 88 subjects (12.2%). There was no significant association between presence of a DDR gene variant and age at diagnosis, gender or reported family history of UC in a first degree relative (n = 48). Among subjects with documented history of UC only without other cancers (n = 195), 24 (12.3%) had P/ LP variants, of which 23 (11.8%) were in a DDR gene. Conclusions: Germline P/LP variants were identified in 15% of UC subjects most of which (92%) were in DDR genes, including 27% in Lynch syndrome genes. PARP and T-cell checkpoint inhibitors may warrant evaluation in subjects with germline DDR mutations. Further validation in unselected UC pts is warranted to propose examining germline P/LP variants in all UC patients.