Non-urothelial bladder cancer: Genomic alterations and patient outcomes.

Abstract

399 Background: Adenocarcinoma (ADA) and squamous cell carcinoma (SCC) are rare, aggressive subtypes of bladder cancer, for which no clear standard of care exists. We report on survival of pts with ADA and SCC and identify potential therapeutic targets using molecular profiling via next generation sequencing (NGS). Methods: Survival trends, demographics, pt characteristics were obtained from the Surveillance, Epidemiology, and End Results (SEER) Database. In a separate cohort, NGS results from 72 specimens (50% metastatic) were also analyzed, using either a hotspot 47 gene panel or a 592 gene assay (Caris Life Sciences, Phoenix, AZ). Results: In SEER, 235,537 cases of bladder cancer were extracted from 1988-2008, of which 3096 were SCC and 671 were ADA. 90% of pts were white, although more African-American patients (15%) were seen in those with ADA. Among all stages, median overall survival (mOS) and 5-yr survival rates were 17.9 mos and 58% for ADA and 15 mos and 37% for SCC. Via NGS testing, 43 patients (28 ADA, 15 SCC) were tested with a 47 gene panel and 29 (21 ADA, 8 SCC) with a 592 gene panel. In the 47 gene panel, among ADA pts, the highest mutation rates were TP53 (57.1%), KRAS (21.4%), SMAD4 (14.8%), PIK3CA (10.7%) and BRCA2 (7.7%). Among SCC pts, the highest mutation rates were TP53 (66.7%), PIK3CA (33.3%), HRAS (14.3%), FBXW7 (6.7%) and AKT1 (6.7%). In the 592 gene assay, the genes with the highest mutation rates in pts with ADA were TP53 (81%), SMAD4 (33.3%), KRAS (23.8%), KMT2C (11.8%), ARID1A (11.1%), BRAF (9.5%), CTNNB1 (9.5%), KMT2D (9.5%), TSC1 (9.5%), KDM6A (5.9%), CDKN2A (5%). Among SCC pts, the highest mutation rates were TP53 (75%), CDKN2A (42.9%), FGFR3 (25%), PIK3CA (25%), CIC (14.3%), KDM6A (14.3%), BRAF (12.5%), BRCA1 (12.5%), FH (12.5%), HRAS (12.5%) and KMT2D (12.5%). Only 1 pt had high TMB. Conclusions: Genomic profiling identifies differences in underlying tumor biology of bladder ADA and SCC, which on a population level are rare with poor survival. Overall, the alterations in the PIK3CA/ AKT/ mTOR and TP53 pathways are similar to what has been reported in UC. Future analyses of these malignancies should investigate the emerging actionable targets, such as TSC1, FGFR3, BRCA1/2 and BRAF.