Molecular profiling of non-urothelial bladder cancer: Adenocarcinoma and squamous cell carcinoma.

Abstract

423 Background: Adenocarcinoma (ADA) and squamous cell carcinoma (SCC) are rare and often aggressive histologic subtypes of bladder cancer. For advanced disease, no clear standard therapies exist and NCCN guidelines suggest only fluorouracil, cisplatin, paclitaxel and ifosfamide as possible options. Thus, novel therapies based on underlying tumor biology are needed. The purpose of this study was to identify potential therapeutic options for these histologic subtypes, utilizing multiplatform tumor profiling. Methods: 49 ADA and 24 SCC specimenswere tested via a multiplatform profiling service (Caris Life Sciences, Phoenix, AZ) consisting of gene sequencing (Sanger or next generation sequencing [NGS]), gene amplification (CISH or FISH), and protein expression (immunohistochemistry [IHC]). 52% of cases were from metastatic sites. Results: Both ADA and SCC exhibited high rates of TP53 aberrations (82.4% and 72.7%, respectively). Sequencing revealed mutations in BRCA2 (14.3%), SMAD4 (12.5%), PTEN (11.8%), KRAS (8.7%), NRAS (5.6%), and KIT (5.3%) in ADA. In addition, PIK3CA (21.4%), HRAS (18.2%), BRCA1 (16.7%), BRCA2 (16.7%), and FBXW7 (9.1%) mutations were detected in SCC. Amplification in EGFR (27.3%) and ERBB2/HER2 (16.7%) were found in ACA. Meanwhile, only one ERBB2 (6.3%) amplification was found in SCC using ISH. MET was not amplified in either ACA or SCC. For both ACA and SCC, EGFR had the highest level of protein expression (100% and 85.7%, respectively). Of note, PD-1 (44.4% in both) and PD-L1 (11.1% and 22.2% in ACA and SCC, respectively) were expressed in both subtypes. Although differential rates of somatic alterations, amplification, and protein expression were found between ADA and SCC, only TLE3 was significant (19.2% versus 60.0%, respectively, p = 0.0154). Conclusions: Differential results in gene alteration, amplification, and protein expression imply the potential utility of tumor profiling in guiding therapeutic decision-making in ADA and SCC of the bladder. PIK3CA/AKT/mTOR pathway aberrations are similar to what has been reported in urothelial bladder cancer. Targeting the PD-1/PD-L1 axis may be a therapeutic option. Further studies are warranted in both diseases.