Adenocarcinoma (ACB), urothelial carcinoma (UCB) and squamous cell carcinoma (SCCB) of the bladder: A Comprehensive Genomic Profiling (CGP) Study.

Abstract

4533 Background: We performed a CGP to compare the genomic alterations (GA) in ABC, UBC and SCCB. Methods: 143 cases of ACB, 2,142 cases of UCB and 83 cases of SCCB were subjected to CGP using a hybrid-capture based assay. Tumor mutational burden (TMB) was determined on 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on 114 loci. PD-L1 expression was determined by IHC. Results: ABC patients were younger and more often female than UBC and SCCB (P < 0.0001). UBC and SCCB had a higher GA/tumor than ABC (P = 0.01). Un-targetable GA were similar in all 3 groups involving TP53 and KRAS. APC GA were more frequent in ABC whereas TERT, CDKN2A/B and DNA-repair genes ( ARID1A and KDM6A) more frequently altered in UBC and SCCB. Targetable MTOR pathway GA ( PIK3CA, TSC1, PTEN) were more frequent in UBC and SCCB as were targetable kinase alterations ( FGFR3 and ERBB2). The UBC and SCCB had a significantly higher TMB than ABC (P < 0.0001) including mean TMB and TMB > 20 mut/Mb (P < 0.0001). CD274 (PD-L1) was amplified more frequently in SCCB than ACB or UBC (P < 0.0001). MSI high status was very uncommon in all tumor types. Conclusions: Deep sequencing reveals that ABC features a widely different genomic profile from UBC and SCCB. UBC has the highest frequencies of targetable kinase GA and high TMB. SCCB has the highest frequencies of IO efficacy predicting biomarkers including mean TMB and PD-L1 amp. Nonetheless, ABC does feature potential kinase targets such as FGFR3 and ERBB2. [Table: see text]