Molecular Taxonomy and Immune Checkpoint Therapy in Bladder Cancer

Molecular profile of micropapillary urothelial carcinoma of the urinary bladder: An analysis of 99 cases by next-generation sequencing

Micropapillary urothelial carcinoma (MPUC) is an aggressive neoplasm with distinct histology. We examined the molecular profile of MPUC and its relationship to patients' clinicopathologic features in 99 patients who underwent next-generation sequencing from 2010 to 2020 at a single institution. The patients included 77 men and 22 women with a mean age of 68 years (range, 24-91 years). Next-generation sequencing was performed on primary (n = 74) and metastatic (n = 25) tumor specimens. Somatic gene mutations were detected in 98 tumors, and the most common mutations were TP53 (n = 71), TERT (n = 49), ARID1A (n = 28), ERBB2 (n = 24), and RB1 (n = 22). Copy number variations were detected in 22 tumors, including ERBB2 (n = 8), CDK12 (n = 3), CCND1 (n = 3), and other genes (n = 8). No gene fusions or microsatellite instability was detected. Human epidermal growth factor receptor 2 (HER2) overexpression was detected more frequently in MPUCs with ERBB2 amplifications than those with ERBB2 mutations. Individual gene mutations did not significantly affect the overall survival, but patients with ERBB2 amplifications had a significantly shorter overall survival than those with ERBB2 mutations (p = 0.043). MPUC demonstrated distinct gene alterations in oncogenes and tumor suppressor genes that may be involved in MPUC's oncogenesis. ERBB2 gene amplifications were associated with HER2 overexpression in MPUC, which may contribute to MPUC's aggressive behavior.

Molecular Classification of Urothelial Carcinoma

Urothelial carcinoma exhibits a wide spectrum of morphologic and molecular heterogeneity. Advances in molecular testing have improved our understanding of the molecular biology of urothelial carcinoma, including recurrent genomic alterations and transcriptomic features, leading to the development of molecular classification schemes with potential therapeutic implications. This review summarizes the molecular characteristics of urothelial carcinoma, focusing on genomic and transcriptomic features, updates on variant histology, and novel biomarkers that may guide contemporary and future clinical management.

Molecular profile of bladder cancer progression to clinically aggressive subtypes

Bladder cancer is a histologically and clinically heterogenous disease. Most bladder cancers are urothelial carcinomas, which frequently develop distinct histological subtypes. Several urothelial carcinoma histological subtypes, such as micropapillary, plasmacytoid, small-cell carcinoma and sarcomatoid, show highly aggressive behaviour and pose unique challenges in diagnosis and treatment. Comprehensive genomic characterizations of the urothelial carcinoma subtypes have revealed that they probably arise from a precursor subset of conventional urothelial carcinomas that belong to different molecular subtypes - micropapillary and plasmacytoid subtypes develop along the luminal pathway, whereas small-cell and sarcomatoid subtypes evolve along the basal pathway. The subtypes exhibit distinct genomic alterations, but in most cases their biological properties seem to be primarily determined by specific gene expression profiles, including epithelial-mesenchymal transition, urothelial-to-neural lineage plasticity, and immune infiltration with distinct upregulation of immune regulatory genes. These breakthrough studies have transformed our view of bladder cancer histological subtype biology, generated new hypotheses for therapy and chemoresistance, and facilitated the discovery of new therapeutic targets.

Plasmacytoid urothelial carcinoma of the urinary bladder-A clinicopathological and molecular analysis of 52 cases

Plasmacytoid urothelial carcinoma (UC) is a rare histologic subtype of bladder cancer that is associated with an aggressive clinical behavior. We analyzed the clinicopathologic and molecular features of plasmacytoid UC in 52 patients from a single institute. The patients included 44 men and 8 women, with a mean age of 64 years (range, 41-91 years). All bladder cancers were high-grade UC, and plasmacytoid component accounted for a mean of 47% of bladder tumors (range, 5-100%). Distinct gene mutations were found in most plasmacytoid UCs (n = 49); the most common mutations were TP53 (n = 30), followed by TERT (n = 20), and CDH1 (n = 18). Copy number analysis was performed in 34 patients, and 13 of them showed copy number variations. Expression of HER2 was analyzed in 18 patients by immunohistochemistry, and 3 of them showed HER2 overexpression, which was confirmed by fluorescence in situ hybridization analysis. Thirty-two patients died of disease in a median of 15 months (range, 1-45 months). No individual gene mutations were significantly associated with clinical outcome, but mutations in the mammalian target of rapamycin (mTOR) pathway, including PICK3CA and PIK3R1 mutations, were associated with a significantly shorter survival duration (p < 0.05). Plasmacytoid UC is an aggressive histologic subtype that demonstrates frequent somatic gene mutations and CNVs, which may underlie its oncogenesis and progression. Gene mutations of the mTOR pathway are associated with poor outcome in a subset of patients with plasmacytoid UC.