Molecular profiling in muscle-invasive bladder cancer: more than the sum of its parts

Prognostic impact of EGFR expression and immunohistochemistry-based "molecular classification" in bladder cancer

Recent genomic studies emphasize the necessity of molecular classification to reflect diverse clinical and pathological characteristics of bladder cancer. Immunohistochemically bladder cancer can be classified into molecular subtypes, including basal, luminal, and p53-like subtypes. Epidermal growth factor receptor (EGFR) is frequently expressed in basal-type bladder cancers and is associated with poor prognosis. In our study, 88 urothelial carcinoma cases were retrospectively analyzed, molecularly subtyped using CK5/6, GATA3, p16 immunohistochemistry and examined for EGFR expressions as well as clinical and histopathological features. Tumor cell scores ≥20 % considered positive, classifying cases as luminal (GATA3-positive), basal (CK5/6-positive), double-positive (both-positive), or double-negative (both-negative). Further division of luminal and basal cases was based on p16 status: luminal-p53 or basal-p53 (p16-positive) and luminal-non-p53 or basal-non-p53 (p16-negative). Among the cases, 4 (4 %) were double-negative, 48 (55 %) luminal-non-p53, 21 (24 %) luminal-p53, 5 (6 %) basal-non-p53, 3 (3 %) basal-p53, and 7 (8 %) double-positive. Our findings revealed that basal-non-p53 type bladder cancer is associated with poor prognosis, muscle invasion, and high-grade cytology. Basal-p53 and double-negative types exhibited less aggressive features compared to basal-non-p53 types, with associations observed with lamina propria invasion and high-grade cytology. Luminal-p53 type demonstrated higher recurrence rates. Luminal-non-p53 type displayed the least aggressive characteristics, often associated with papillary histopathology. EGFR expression was found to be high in basal-non-p53 type and was further correlated with adverse prognostic indicators, lamina propria invasion, and high-grade cytology. The identification of molecular subtypes and EGFR expression through immunohistochemistry, alongside traditional bladder cancer classifications, enhances tumor behavior prediction and supports effective clinical management.

Metastasis development in non-muscle-invasive bladder cancer

Non-muscle-invasive bladder cancer (NMIBC) is the most common type of bladder cancer presentation and is characterized by a varying probability of recurrence and progression. Sporadically, patients with NMIBC might also develop tumour metastases without any pathological evidence of muscle-invasive disease within the bladder, a condition known as metastatic NMIBC. In the published literature, this phenomenon is limited to several case reports and small reviews, with few data regarding the possible aetiologies. Several possible factors can be potentially associated with metastatic NMIBC, including tumour understaging, the number of transurethral resection procedures received by the patient, the presence of circulating tumour cells, the modality used for diagnostic cystoscopy and possible gender-associated differences. In this Perspective, our aim was to integrate and report currently available data on this relatively rare entity and provide some potential aetiological explanations.

The Role of Immunohistochemistry as a Surrogate Marker in Molecular Subtyping and Classification of Bladder Cancer

BACKGROUND/OBJECTIVES

Bladder cancer (BC) is a highly heterogeneous disease, presenting clinical challenges, particularly in predicting patient outcomes and selecting effective treatments. Molecular subtyping has emerged as an essential tool for understanding the biological diversity of BC; however, its implementation in clinical practice remains limited due to the high costs and complexity of genomic techniques. This review examines the role of immunohistochemistry (IHC) as a surrogate marker for molecular subtyping in BC, highlighting its potential to bridge the gap between advanced molecular classifications and routine clinical application; Methods: We explore the evolution of taxonomic classification in BC, with a particular focus on cytokeratin (KRT) expression patterns in normal urothelium, which are key to identifying basal and luminal subtypes. Furthermore, we emphasise the need for consensus on IHC markers to reliably define these subtypes, facilitating wider and standardised clinical use. The review also analyses the application of IHC in both muscle-invasive (MIBC) and non-muscle-invasive bladder cancer (NMIBC), with particular attention to the less extensively studied NMIBC cases. We discuss the practical advantages of IHC for subtyping, including its cost effectiveness and feasibility in standard pathology laboratories, alongside ongoing challenges such as the requirement for standardised protocols and external validation across diverse clinical settings; Conclusions: While IHC has limitations, it offers a viable alternative for laboratories lacking access to advanced molecular techniques. Further research is required to determine the optimal combination of markers, establish a consensus diagnostic algorithm, and validate IHC through large-scale trials. This will ultimately enhance diagnostic accuracy, guide treatment decisions, and improve patient outcomes.

Advances, recognition, and interpretation of molecular heterogeneity among conventional and subtype histology of urothelial carcinoma (UC): a survey among urologic pathologists and comprehensive review of the literature

AIMS

Urothelial carcinoma (UC) demonstrates significant molecular and histologic heterogeneity. The WHO 2022 classification has hinted at adding molecular signatures to the morphologic diagnosis. As morphology and associated molecular repertoire may potentially translate to choices of and response to therapy and relapse rate, broader acceptability of recognizing these key features among uropathologists is needed. This prompted an international survey to ascertain the practice patterns in classical/subtype UC among uropathologists across the globe.

METHODS AND RESULTS

A survey instrument was shared among 98 uropathologists using SurveyMonkey software. Anonymized respondent data were analysed. The response rate was 85%. A majority were in concordance with the profiles of luminal (93%) and basal (82%) types. Opinion on the FGFR3 testing platform was variable. While 95% concurred that TERT promoter mutation is the key driver in UC, 72% had the opinion that APOBEC mutagenesis is the main signature in muscle invasive bladder cancer (MIBC). Uropathologists have divergent opinions on MIBC and ERCC2 mutations. Among the participants, 94% would quantify aggressive micropapillary and sarcomatoid histology, while 88% would reevaluate another transurethral resection of the bladder tumour specimen in nonmuscle invasive tumour with micropapillary, small cell, or sarcomatoid histology. A leading number agreed to specific molecular signatures of micropapillary (93%), plasmacytoid (97%), and small cell (86%) subtypes. Ninety-six percent of participants agreed that a small-cell component portends a more aggressive course and should be treated with neoadjuvant chemotherapy and 63% would perform HER2/neu testing only on oncologist's request in advanced tumours. Ninety percent agreed that microsatellite instability testing, although not a standard protocol, should be considered in young patients with upper tract UC. Eighty-six percent agreed that UC with high tumour mutational burden would be a better candidate for immunotherapy.

CONCLUSION

In the era of precision medicine, enhanced understanding of molecular heterogeneity of UC will contribute to better therapeutic options, novel biomarker discovery, innovative management protocols, and outcomes. Our survey provides a broad perspective of pathologists' perceptions and experience regarding incorporation of histomolecular approaches to "personalize" therapy. Due to variable clinical adoption, there is a need for additional data using uniform study criteria. This will drive generation of best practice guidelines in this area for widespread and consistent clinical utility.

Development of a novel immunocompetent murine tumor model for urothelial carcinoma using in vivo electroporation

A lack of advanced preclinical mouse tumor models impedes the progress in urothelial carcinoma research. We present here a novel fast, robust, reliable, and highly reproducible model for the genetic induction of bladder cancer in immunocompetent mice. Different sets of oncogenic transposons (Cmyc, Kras) and Cre drivers were transfected into the murine bladder wall of two different genetic backgrounds (Trp53fl/fl and BrafV600E, Ptenfl/fl, Ctnnb1exon3-fl/fl). Transfection was carried out using in vivo electroporation of the bladder after surgical exploration and transmural or transurethral intravesical plasmid injection. Up to 100% of animals developed urothelial carcinomas of the bladder. Time to tumor onset ranged from 16 to 97 days with a median of approximately 23 days in the fastest groups. Histological examination identified orthotopic urothelial carcinomas in most cases, in some experimental groups up to 100%. The resulting tumors were highly invasive and often metastatic. Metastases were found in up to 100% of tumor bearing mice per group. Taken together, this study establishes the proof-of-principle that in vivo electroporation can be versatilely employed as a reliable, fast, and robust method for the highly reproducible induction of urothelial carcinomas in the murine bladder wall. This novel murine tumor model could pave the way towards more easily modelling subtype specific urothelial carcinomas in mice.

MTAP protein status is highly concordant with CDKN2A fluorescent in situ hybridization and allows stratification of the luminal subtype in muscle-invasive bladder cancer

AIMS

Loss of heterozygosity in chromosome 9p21, common in urothelial carcinoma (UC), typically involves deletion of CDKN2A and MTAP genes. MTAP loss is emerging as a promising therapeutic target and predictive biomarker in UC. This single-centrre retrospective study examined the incidence of CDKN2A deletions and MTAP loss in muscle-invasive bladder cancer (MIBC) and metastatic urothelial carcinoma (mUC), investigating their correlations with clinical, pathological, and genomic features, as well as patient outcomes.

METHODS

Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) were performed on 302 MIBC specimens and 63 biopsy-proven metachronous urothelial metastases to assess CDKN2A deletions and MTAP protein expression.

RESULTS

CDKN2A homozygous deletion (HD), identified in 30.3% of MIBCs, and MTAP loss, found in 28.8% of MIBCs, were both significantly associated with the luminal-URO subtype, FGFR3 mutations, and normal/wildtype p53 IHC (P < 0.05). Loss of MTAP expression was significantly correlated with CDKN2A HD, with 84.0% sensitivity, 92.3% negative predictive value (NPV), 96.3% specificity, and 91.9% positive predictive value (PPV). MTAP expression was 100% concordant between primary tumours and nodal metastases. Patients with MTAP loss had a higher incidence of visceral metastases (50%) compared to bone/soft tissue (35.7%) and nodes (14.3%). Mean progression-free survival and overall survival were shorter for patients with MTAP loss, although not statistically significant.

CONCLUSION

Our findings highlight CDKN2A HD and MTAP loss as prevalent genetic alterations in MIBC and mUC, particularly within the luminal-URO subtype and FGFR3-mutated, p53-normal/wildtype tumours. MTAP IHC can serve as a surrogate marker for 9p21.3 HD, highlighting its clinical relevance and potential as a therapeutic target and predictive biomarker in MIBC.

PD-L1 expression and its correlation with tumor biomarkers in Chinese urothelial bladder cancer

Data on prevalence of programmed death ligand-1 (PD-L1) expression and its correlation with tumor biomarkers in Chinese patients with muscle-invasive urothelial bladder cancer (MIUBC) are scarce. We investigated the prevalence of PD-L1 expression, PD-L1 expression in tumor cells (TC) and immune cells (IC), and its correlation with tumor biomarkers (CD8+ T cells and tumor mutation burden [TMB]) in Chinese patients with newly diagnosed MIUBC (NCT03433924). Of 248 patients enrolled, 229 with PD-L1 data available were analysed. High PD-L1 expression (≥ 25% of TC or IC with PD-L1 expression) was observed in 120 (52.4%) patients. 59 cases showed positive staining in ≥ 25% of TC, and 82 cases had positive staining in ≥ 25% of IC. High expression of CD8+ T cell and TMB (> 10 mutations/megabase) was observed in 44.5% and 54.1% patients, respectively. A positive correlation was observed between percentage of TC with membrane PD-L1 positivity and CD8+ T cells (0.34; P < 0.001) and between IC with membrane PD-L1 positivity and CD8+ T cells (0.44; P < 0.001). There is high prevalence of PD-L1 expression in Chinese patients with MIUBC, suggesting that a sizable subset of patients could benefit from immunotherapy. The correlation of PD-L1 expression with tumor biomarkers provide clues for mechanisms underlying the effects of biomarkers for predicting efficacy.

Similar genetic profile in early and late stage urothelial tract cancer

INTRODUCTION

Urothelial tract cancer (UTC) ranks as the tenth most prevalent cancer and holds the seventh position in terms of mortality worldwide. Despite its prevalence and mortality ranking, there are still gaps in the knowledge of the mutational landscape in patients with advanced disease who have limited therapeutic options after multiple lines of prior treatment. This study compares the genomic and transcriptomic landscape, and targeted treatment options between metastatic UTC (mUTC) patients treated with multiple lines of therapy compared to newly diagnosed, untreated Muscle Invasive Bladder Cancer (MIBC).

METHODS

We compared genomic and clinical data from two cohorts: mUTC patients who received multiple lines of therapy and were referred to the Copenhagen Prospective Personalized Oncology (CoPPO) project at Rigshospitalet, University of Copenhagen. Data for MIBC UTC patients were acquired from the Cancer Genome Atlas Bladder Cancer (TCGA BLCA) cohort. Biopsies in CoPPO were performed at the time of enrollment. 523 highly important cancer-related genes (TrueSight Oncology-500 targeted sequencing panel) were used from both cohorts for comparative analysis. Analyses included RNA count data to compare predicted molecular subtypes in each cohort separately.

RESULTS

Patients from the CoPPO cohort had a lower median age at first-line treatment than the TCGA BLCA cohort, with no significant gender disparity. The predominant histology was urothelial cell carcinoma in both cohorts. Genomic analysis revealed no significant difference between the top mutated genes in the two cohorts, specifically looking into DNA damage repair genes. Molecular subtyping indicated a higher frequency of neuroendocrine differentiation in the CoPPO cohort. 13% of patients in the CoPPO cohort received targeted therapy based on genomic findings, and 16% received non-targeted treatment, totaling 29% receiving CoPPO treatment (9 patients). The remaining 71% received best supportive care. Kaplan-Meier analysis showed a non-significant survival benefit for the intervention group in the CoPPO cohort.

CONCLUSION

When focusing on 523 highly relevant cancer genes, the mutational profile of mUTC patients who have undergone numerous treatment lines resembles that of newly diagnosed MIBC. These alterations can be targeted, indicating the potential advantage of early genomic testing for personalized treatment within clinical trials.

Revealing the potential of solute carrier family 31 (copper transporters), member 1: Insights into its role in bladder cancer progression and therapeutic implications

Introduction: Bladder cancer represents a significant public health concern with diverse genetic alterations influencing disease onset, progression, and therapy response. In this study, we explore the multifaceted role of Solute Carrier Family 31 Member 1 (SLC31A1) in bladder cancer, a pivotal gene involved in copper homeostasis. Methods: Our research involved analyzing the SLC31A1 gene expression via RT-qPCR, promoter methylation via targeted bisulfite sequencing, and mutational status via Next Generation Sequencing (NGS) using the clinical samples sourced by the local bladder cancer patients. Later on, The Cancer Genome Atlas (TCGA) datasets were utilized for validation purposes. Moreover, prognostic significance, gene enrichment terms, and therapeutic drugs of SLC31A1 were also explored using KM Plotter, DAVID, and DrugBank databases. Results: We observed that SLC31A1 was significantly up-regulated at both the mRNA and protein levels in bladder cancer tissue samples, suggesting its potential involvement in bladder cancer development and progression. Furthermore, our investigation into the methylation status revealed that SLC31A1 was significantly hypomethylated in bladder cancer tissues, which may contribute to its overexpression. The ROC analysis of the SLC31A1 gene indicated promising diagnostic potential, emphasizing its relevance in distinguishing bladder cancer patients from normal individuals. However, it is crucial to consider other factors such as cancer stage, metastasis, and recurrence for a more accurate evaluation in the clinical context. Interestingly, mutational analysis of SLC31A1 demonstrated only benign mutations, indicating their unknown role in the SLC31A1 disruption. In addition to its diagnostic value, high SLC31A1 expression was associated with poorer overall survival (OS) in bladder cancer patients, shedding light on its prognostic relevance. Gene enrichment analysis indicated that SLC31A1 could influence metabolic and copper-related processes, further underscoring its role in bladder cancer. Lastly, we explored the DrugBank database to identify potential therapeutic agents capable of reducing SLC31A1 expression. Our findings unveiled six important drugs with the potential to target SLC31A1 as a treatment strategy. Conclusion: Our comprehensive investigation highlights SLC31A1 as a promising biomarker for bladder cancer development, progression, and therapy.

Feasibility and Impact of Immunohistochemistry-based Molecular Subtyping for Muscle-invasive Bladder Cancer in Patients Treated with Radiation-based Therapy

Background

Distinct molecular subtypes of muscle-invasive bladder cancer (MIBC) have been identified via gene expression profiling.

Objective

We investigated the feasibility of a simple immunohistochemistry (IHC)-based Lund subtyping method and the association of MIBC subtypes with oncological outcomes for patients after bladder-preserving radiation-based therapy.

Design setting and participants

Transurethral resected tumor tissues from 104 patients treated with radiation-based therapy were sampled on tissue microarray blocks.

Outcome measurements and statistical analysis

The expression of KRT5, GATA3, and p16 proteins was scored via digital image analysis. Hierarchical clustering was used to classify tumors as the basal subtype or one of two luminal subtypes: genomically unstable (GU) or urothelial-like (URO). Subtypes were evaluated for association with complete response (CR), recurrence-free survival (RFS), and overall survival (OS).

Results and limitations

The median OS was 43 mo (95% confidence interval 19-77) and median follow-up was 55 mo (interquartile range 39-75). Age and clinical stage had a significant impact on OS (p < 0.05). IHC-based subtype classification was feasible in most patients (89%). The subtype was basal in 23.6%, GU in 14.0%, URO in 31.2%, and unclassified in 31.2% of patients. No significant differences in CR, RFS, or OS were observed between the molecular subtypes. Limitations include the retrospective design and relatively small sample size.

Conclusions

IHC-based molecular MIBC subtyping using a three-antibody algorithm is feasible in most patients treated with radiation-based therapy. MIBC subtype was not associated with response or survival. Further prospective studies are warranted to confirm the lack of association between molecular subtype and survival in patients treated with trimodal therapy.

Patient summary

For patients with invasive bladder cancer treated with radiation-based therapy, we classified tumors into different subtypes using just three molecular stains. This method is cheaper and more widely available than the usual approach. However, we did not find an association between different cancer subtypes and survival.

Homologous recombination mRNAs (RAD21, RAD50 and BARD1) have a potentially poor prognostic role in ERBB2-low bladder cancer patients

Human epidermal growth factor receptor 2 (HER2/ERBB2) factor is known to be implicated in many malignancies and the potential of it as a prognostic biomarker was reported years ago. Molecular subtypes of HER2/ERBB2 negative and positive with distinct clinical outcomes have been identified in recent years; however, it is still under investigation for bladder cancer. This study evaluates the biological and prognostic significance of RAD21, RAD50 and BARD1 (homologous recombination biomarkers) mRNA levels with ERBB2 low and high expression to explore their impact on bladder cancer patient survival and cancer aggressiveness. The expression of ERBB2, RAD21, RAD50 and BARD1 mRNA levels was assessed in The Cancer Genome Atlas (TCGA) bladder cancer dataset along with four validation cohorts. Outcome analysis was evaluated using disease-free survival (DFS) and overall survival (OS). Univariate and multivariate analysis were used to evaluate the relationship between RAD21, RAD50, BARD1 and ERBB2 expression and clinicopathological variables. A significant increase in mRNA expression levels of RAD21, RAD50 and BARD1 was noticed in ERBB2-low patients compared to ERBB2-high patients. This overexpression of the homologous recombination repair transcripts was associated with poor outcome in ERBB2-low tumors, not in ERBB2-high tumors. Furthermore, the combined expression of high RAD21/RAD50, high RAD21/BARD1 or high RAD50/BARD1 were significantly associated with worse DFS and a better outcome for those with low co-expression in the ERBB2-low cohort. High expression of either RAD21/RAD50 or RAD21/BARD1 in ERBB2-low cohort associated with higher chance of metastasis. In addition, gene expression of BARD1 alone or in combination with RAD50 acted as an independent prognostic factor for worst survival. The data presented in this study reveal a connection between RAD21, RAD50, BARD1 and ERBB2 and patient survival. Importantly, it provided novel findings and potential prognostic markers, particularly in ERBB2-low bladder cancer.

Optimizing identification of consensus molecular subtypes in muscle-invasive bladder cancer: a comparison of two sequencing methods and gene sets using FFPE specimens

BACKGROUND

Molecular subtypes predict prognosis in muscle-invasive bladder cancer (MIBC) and are explored as predictive markers. To provide a common base for molecular subtyping and facilitate clinical applications, a consensus classification has been developed. However, methods to determine consensus molecular subtypes require validation, particularly when FFPE specimens are used. Here, we aimed to evaluate two gene expression analysis methods on FFPE samples and to compare reduced gene sets to classify tumors into molecular subtypes.

METHODS

RNA was isolated from FFPE blocks of 15 MIBC patients. Massive analysis of 3' cDNA ends (MACE) and the HTG transcriptome panel (HTP) were used to retrieve gene expression. We used normalized, log2-transformed data to call consensus and TCGA subtypes with the consensusMIBC package for R using all available genes, a 68-gene panel (ESSEN1), and a 48-gene panel (ESSEN2).

RESULTS

Fifteen MACE-samples and 14 HTP-samples were available for molecular subtyping. The 14 samples were classified as Ba/Sq in 7 (50%), LumP in 2 (14.3%), LumU in 1 (7.1%), LumNS in 1 (7.1%), stroma-rich in 2 (14.3%) and NE-like in 1 (7.1%) case based on MACE- or HTP-derived transcriptome data. Consensus subtypes were concordant in 71% (10/14) of cases when comparing MACE with HTP data. Four cases with aberrant subtypes had a stroma-rich molecular subtype with either method. The overlap of the molecular consensus subtypes with the reduced ESSEN1 and ESSEN2 panels were 86% and 100%, respectively, with HTP data and 86% with MACE data.

CONCLUSION

Determination of consensus molecular subtypes of MIBC from FFPE samples is feasible using various RNA sequencing methods. Inconsistent classification mainly involves the stroma-rich molecular subtype, which may be the consequence of sample heterogeneity with (stroma)-cell sampling bias and highlights the limitations of bulk RNA-based subclassification. Classification is still reliable when analysis is reduced to selected genes.

Precision Medicine in Bladder Cancer: Present Challenges and Future Directions

Bladder cancer (BC) is characterized by significant histopathologic and molecular heterogeneity. The discovery of molecular pathways and knowledge of cellular mechanisms have grown exponentially and may allow for better disease classification, prognostication, and development of novel and more efficacious noninvasive detection and surveillance strategies, as well as selection of therapeutic targets, which can be used in BC, particularly in a neoadjuvant or adjuvant setting. This article outlines recent advances in the molecular pathology of BC with a better understanding and deeper focus on the development and deployment of promising biomarkers and therapeutic avenues that may soon make a transition into the domain of precision medicine and clinical management for patients with BC.

Clinicopathological Features and Survival Analysis in Molecular Subtypes of Muscle-Invasive Bladder Cancer

Molecular subtyping of bladder cancer (BC) aims to capture the biological heterogeneity of this complex disease in order to provide better patient risk stratification. Immunohistochemical (IHC) markers are regarded as promising surrogates to classify BCs into luminal and basal subtypes in routine practice. We investigated the correlation between the molecular subclassification, assessed through IHC, and the conventional prognostic variables of a cohort of 93 muscle-invasive BCs (MIBCs), with a focus on the pattern of muscularis propria (MP) invasion, and evaluated their association with outcome. Basal, luminal, double-positive (DP), and double-negative (DN) phenotypes were identified according to the coordinate expression of 1 basal (CK5/6) and 2 luminal (CK20, GATA3) markers, and accounted for 33.3%, 32.3%, 3.2%, and 31.2% (Scheme #1) and 9.7%, 60.2%, 26.9%, and 3.2% (Scheme #2). There was a significant association between the pattern of MP invasion and the molecular subtypes according to Scheme #2, in that all 8 basal and DN cases, as well as 83% of DP cases, had a non-infiltrative invasion pattern. No consistent differences were observed in terms of OS and CSS between the molecular subtypes obtained through surrogate IHC markers. In keeping with previous studies, we report the correlation between the identification of BC subtypes and the presence of morphological prognostic factors, supporting the need for a comprehensive pathological evaluation, including clinicopathological and molecular parameters, in order to improve the diagnosis and management of MIBC.

Characterization of the tumor-infiltrating immune repertoire in muscle invasive bladder cancer

Introduction

Muscle-invasive bladder cancer (MIBC) is a heterogeneous disease with several taxonomic molecular subtypes showing different genetic, clinical, and epidemiological profiles. It has been suggested that MIBC-subtypes follow different tumorigenesis pathways playing decisive roles at different stages of tumor development, resulting in distinct tumor microenvironment containing both innate and adaptive immune cells (T and B lymphocytes). We aim to characterize the MIBC tumor microenvironment by analyzing the tumor-infiltrating B and T cell repertoire according to the taxonomic molecular subtypes.

Methods

RNAseq data from 396 MIBC samples included in TCGA were considered. The subtype information was collected from the international consensus taxonomic classification describing six subtypes: Basal/Squamous-like (Ba/Sq), Luminal papillary (LumP), Luminal non-Specify (LumNS), Luminal unstable (LumU), Stroma-rich, and Neuroendocrine-like (NE-like). Using MiXCR, we mapped the RNA read sequences to their respective B-cell receptor (BCR) and T-cell receptor (TCR) clonotypes. To evaluate the BCR and TCR differences among subtypes, we compared diversity measures (richness and diversity) using a Wilcoxon test and we performed a network analysis to characterize the clonal expansion. For the survival analysis stratified by subtypes, Cox regression models adjusted for age, region, and pathological stage were performed.

Results

Overall, we found different patterns of tumor-infiltrating immune repertoire among the different MIBC subtypes. Stroma-rich and Ba/Sq tumors showed the highest BCR and TCR infiltration while LumP showed the lowest. In addition, we observed that the Ba/Sq and Stroma-rich tumors were more clonally expanded than the Luminal subtypes. Moreover, higher TCR richness and diversity were significantly associated with better survival in the Stroma-rich and Ba/Sq subtypes.

Discussion

This study provides evidence that MIBC subtypes present differences in the tumor microenvironment, in particular, the Ba/Sq and the Stroma-rich are related with a higher tumoral-infiltrating immune repertoire, which seems to be translated into better survival. Determining the causes of the different tumoral-infiltrating immune repertoire according to the MIBC molecular subtypes will help to improve our understanding of the disease and the distinct responses to immunotherapy of MIBC.

Scoring Systems for Immunohistochemistry in Urothelial Carcinoma

Immunohistochemistry is widely used in diagnostic and scientific analysis of urothelial carcinoma. Objective interpretation of staining results is mandatory for accuracy and comparability in diagnostic and therapeutic patient care as well as research.Herein we summarize and explain standardized microscopic evaluation and scoring approaches for immunohistochemical stainings. We focus on commonly used and generally feasible approaches for different cellular compartments and comment on their utility in diagnostics and research practice.

Single-cell sequencing technologies in bladder cancer research: Applications and challenges

Bladder cancer is among the most common malignant tumors with highly heterogeneous molecular characteristics. Despite advancements of the available therapeutic options, several bladder cancer patients exhibit unsatisfactory clinical outcomes. The lack of specific biomarkers for effective targeted therapy or immunotherapy remains a major obstacle in treating bladder cancer. The rapid development of single-cell techniques is transforming our understanding of the intra-tumoral heterogeneity, thereby providing us with a powerful high-throughput sequencing tool that can reveal tumorigenesis, progression, and invasion in bladder tumors. In this review, we summarise and discuss how single-cell sequencing technologies have been applied in bladder cancer research, to advance our collective knowledge on the heterogeneity of bladder tumor cells, as well as to provide new insights into the complex ecosystem of the tumor microenvironment. The application of single-cell approaches also uncovers the therapeutic resistance mechanism in bladder cancer and facilitates the detection of urinary-exfoliated tumor cells. Moreover, benefiting from the powerful technical advantages of single-cell techniques, several key therapeutic targets and prognostic models of bladder cancer have been identified. It is hoped that this paper can provide novel insights into the precision medicine of bladder cancer.

Are We Ready to Implement Molecular Subtyping of Bladder Cancer in Clinical Practice? Part 2: Subtypes and Divergent Differentiation

Following several attempts to achieve a molecular stratification of bladder cancer (BC) over the last decade, a "consensus" classification has been recently developed to provide a common base for the molecular classification of bladder cancer (BC), encompassing a six-cluster scheme with distinct prognostic and predictive characteristics. In order to implement molecular subtyping (MS) as a risk stratification tool in routine practice, immunohistochemistry (IHC) has been explored as a readily accessible, relatively inexpensive, standardized surrogate method, achieving promising results in different clinical settings. The second part of this review deals with the pathological and clinical features of the molecular clusters, both in conventional and divergent urothelial carcinoma, with a focus on the role of IHC-based subtyping.

Are We Ready to Implement Molecular Subtyping of Bladder Cancer in Clinical Practice? Part 1: General Issues and Marker Expression

Bladder cancer (BC) is a heterogeneous disease with highly variable clinical and pathological features, and resulting in different outcomes. Such heterogeneity ensues from distinct pathogenetic mechanisms and may consistently affect treatment responses in single patients. Thus, over the last few years, several groups have developed molecular classification schemes for BC, mainly based on their mRNA expression profiles. A “consensus” classification has recently been proposed to combine the published systems, agreeing on a six-cluster scheme with distinct prognostic and predictive features. In order to implement molecular subtyping as a risk-stratification tool in routine practice, immunohistochemistry (IHC) has been explored as a readily accessible, relatively inexpensive, standardized surrogate method, achieving promising results in different clinical settings. The first part of this review deals with the steps resulting in the development of a molecular subtyping of BC, its prognostic and predictive implications, and the main features of immunohistochemical markers used as surrogates to stratify BC into pre-defined molecular clusters.

Immunohistochemistry subtyping of urothelial carcinoma is feasible in the daily practice

The preferred treatment of choice in muscle-invasive bladder cancer (MIBC) is usually transurethral resection followed by cystectomy, with neoadjuvant chemotherapy being a second option. As the treatment is associated with relevant side effects, a great effort is being made to improve the selection of patients, with molecular subtyping being one of the main strategies. Our aim was to develop an immunohistochemical algorithm for subtyping MIBCs. After a literature review, we have developed a simple algorithm to subtype MIBCs based on their morphology and three common antibodies: GATA3, CK5/6, and p16. We applied it to 113 muscle-invasive carcinomas. The positivity threshold for GATA3 and CK5/6 was 20% with at least moderate intensity, while p16 was 70% with moderate to intense nuclear and cytoplasmic staining. Cases GATA3 + CK5/6 - were considered luminal, while cases GATA3 - CK5/6 + were classified as nonluminal/basal squamous. Luminal p16 + cases were labeled as genomically unstable and luminal p16 - as Uro-like. Cases GATA3 + CK5/6 + with a predominantly basal pattern were labeled luminal, while diffuse cases were labeled nonluminal/basal squamous. All GATA3-CK5/6 - cases were considered nonluminal and were divided into mesenchymal-like or neuroendocrine, depending on the morphology. We were able to classify the 113 cases as: 82 (72.57%) were luminal, being 47 Uro-like (41.59%) and 35 (30.97%) genomically unstable; 31 (27.43%) were nonluminal, being 24 basal/squamous (21.24%), two (1.76%) mesenchymal-like, and five (4.42%) neuroendocrine like. We have achieved a feasible and cost-effective algorithm to subtype MIBCs from morphological features and the use of three common antibodies. Further studies in external cohorts are necessary to validate these results.

Molecular Oncology of Bladder Cancer from Inception to Modern Perspective

Within the last forty years, seminal contributions have been made in the areas of bladder cancer (BC) biology, driver genes, molecular profiling, biomarkers, and therapeutic targets for improving personalized patient care. This overview includes seminal discoveries and advances in the molecular oncology of BC. Starting with the concept of divergent molecular pathways for the development of low- and high-grade bladder tumors, field cancerization versus clonality of bladder tumors, cancer driver genes/mutations, genetic polymorphisms, and bacillus Calmette-Guérin (BCG) as an early form of immunotherapy are some of the conceptual contributions towards improving patient care. Although beginning with a promise of predicting prognosis and individualizing treatments, "-omic" approaches and molecular subtypes have revealed the importance of BC stem cells, lineage plasticity, and intra-tumor heterogeneity as the next frontiers for realizing individualized patient care. Along with urine as the optimal non-invasive liquid biopsy, BC is at the forefront of the biomarker field. If the goal is to reduce the number of cystoscopies but not to replace them for monitoring recurrence and asymptomatic microscopic hematuria, a BC marker may reach clinical acceptance. As advances in the molecular oncology of BC continue, the next twenty-five years should significantly advance personalized care for BC patients.

Immunohistochemical Assays for Bladder Cancer Molecular Subtyping: Optimizing Parsimony and Performance of Lund Taxonomy Classifiers

Transcriptomic and proteomic profiling classify bladder cancers into luminal and basal molecular subtypes, with controversial prognostic and predictive associations. The complexity of published subtyping algorithms is a major impediment to understanding their biology and validating or refuting their clinical use. Here, we optimize and validate compact algorithms based on the Lund taxonomy, which separates luminal subtypes into urothelial-like (Uro) and genomically unstable (GU). We characterized immunohistochemical expression data from two muscle-invasive bladder cancer cohorts (n=193, n=76) and developed efficient decision tree subtyping models using 4-fold cross-validation. We demonstrated that a published algorithm using routine assays (GATA3, KRT5, p16) classified basal/luminal subtypes and basal/Uro/GU subtypes with 86%-95% and 67%-86% accuracies, respectively. KRT14 and RB1 are less frequently used in pathology practice but achieved the simplest, most accurate models for basal/luminal and basal/Uro/GU discrimination, with 93%-96% and 85%-86% accuracies, respectively. More complex models with up to eight antibodies performed no better than simpler two- or three-antibody models. We conclude that simple immunohistochemistry classifiers can accurately identify luminal (Uro, GU) and basal subtypes and are appealing options for clinical implementation.

Molecular Subtypes as a Basis for Stratified Use of Neoadjuvant Chemotherapy for Muscle-Invasive Bladder Cancer-A Narrative Review

There are no established biomarkers to guide patient selection for neoadjuvant chemotherapy prior to radical cystectomy for muscle-invasive bladder cancer. Recent studies suggest that molecular subtype classification holds promise for predicting chemotherapy response and/or survival benefit in this setting. Here, we summarize and discuss the scientific literature examining transcriptomic or panel-based molecular subtyping applied to neoadjuvant chemotherapy-treated patient cohorts. We find that there is not sufficient evidence to conclude that the basal subtype of muscle-invasive bladder cancer responds well to chemotherapy, since only a minority of studies support this conclusion. More evidence indicates that luminal-like subtypes may have the most improved outcomes after neoadjuvant chemotherapy. There are also conflicting data concerning the association between biopsy stromal content and response. Subtypes indicative of high stromal infiltration responded well in some studies and poorly in others. Uncertainties when interpreting the current literature include a lack of reporting both response and survival outcomes and the inherent risk of bias in retrospective study designs. Taken together, available studies suggest a role for molecular subtyping in stratifying patients for receiving neoadjuvant chemotherapy. The precise classification system that best captures such a predictive effect, and the exact subtypes for which other treatment options are more beneficial remains to be established, preferably in prospective studies.

Spatial and Temporal Heterogeneity of Tumor-Infiltrating Lymphocytes in Advanced Urothelial Cancer

Checkpoint inhibitors targeting PD-(L)1 induce objective responses in 20% of patients with metastatic urothelial cancer (UC). CD8+ T cell infiltration has been proposed as a putative biomarker for response to checkpoint inhibitors. Nevertheless, data on spatial and temporal heterogeneity of tumor-infiltrating lymphocytes in advanced UC are lacking. The major aims of this study were to explore spatial heterogeneity for lymphocyte infiltration and to investigate how the immune landscape changes during the disease course. We performed multiplex immunohistochemistry to assess the density of intratumoral and stromal CD3+, CD8+, FoxP3+ and CD20+ immune cells in longitudinally collected samples of 49 UC patients. Within these samples, spatial heterogeneity for lymphocyte infiltration was observed. Regions the size of a 0.6 tissue microarray core (0.28 mm2) provided a representative sample in 60.6 to 71.6% of cases, depending on the cell type of interest. Regions of 3.30 mm2, the median tumor surface area in our biopsies, were representative in 58.8 to 73.8% of cases. Immune cell densities did not significantly differ between untreated primary tumors and metachronous distant metastases. Interestingly, CD3+, CD8+ and FoxP3+ T cell densities decreased during chemotherapy in two small cohorts of patients treated with neoadjuvant or palliative platinum-based chemotherapy. In conclusion, spatial heterogeneity in advanced UC challenges the use of immune cell infiltration in biopsies as biomarker for response prediction. Our data also suggests a decrease in tumor-infiltrating T cells during platinum-based chemotherapy.

RAF1 amplification drives a subset of bladder tumors and confers sensitivity to MAPK-directed therapeutics

Bladder cancer is a genetically heterogeneous disease, and novel therapeutic strategies are needed to expand treatment options and improve clinical outcomes. Here, we identified a unique subset of urothelial tumors with focal amplification of the RAF1 (CRAF) kinase gene. RAF1-amplified tumors had activation of the RAF/MEK/ERK signaling pathway and exhibited a luminal gene expression pattern. Genetic studies demonstrated that RAF1-amplified tumors were dependent upon RAF1 activity for survival, and RAF1-activated cell lines and patient-derived models were sensitive to available and emerging RAF inhibitors as well as combined RAF plus MEK inhibition. Furthermore, we found that bladder tumors with HRAS- or NRAS-activating mutations were dependent on RAF1-mediated signaling and were sensitive to RAF1-targeted therapy. Together, these data identified RAF1 activation as a dependency in a subset making up nearly 20% of urothelial tumors and suggested that targeting RAF1-mediated signaling represents a rational therapeutic strategy.

Molecular Classification of Bladder Urothelial Carcinoma Using NanoString-Based Gene Expression Analysis

Simple Summary

Our study aimed to apply a quantitative method based on mRNA counting as nCounter (NanoString Technologies, Inc). This method can obtain precise and accurate measures of RNA expression compared to RT-PCR, and which might represent an alternative to the NGS-genomic/transcriptomic profiling frequently used to generate molecular data in bladder cancer and provide clinically meaningful datasets for the molecular classification of bladder cancer. The current study generated a four-gene classifier, incorporating GATA3 and KRT20 (typically related to luminal molecular subtype) and KRT5 and KRT14 (typically related to basal molecular subtype). This methodology allowed us to explore differences in clinicopathologic parameters and potential sensitivities to ICI immunotherapy in a cohort series of 91 urothelial carcinomas of the bladder.

Abstract

Molecular classification of bladder carcinoma is a relevant topic in modern bladder cancer oncology due to its potential to improve oncological outcomes. The available molecular classifications are generally based on transcriptomic profiles, generating highly diverse categories with limited correlation. Implementation of molecular classification in practice is typically limited due to the high complexity of the required technology, the elevated costs, and the limited availability of this technology worldwide. We have conducted a gene expression analysis using a four-gene panel related to luminal and basal subtypes in a series of 91 bladder cancer cases. NanoString-based gene expression analysis using typically luminal (GATA3+/KRT20+) and basal markers (KRT14+/KRT5+/GATA3low/-/KRT20low/-) classified urothelial bladder carcinoma samples as luminal, basal, and a third category (KRT14-/KRT5-/GATA3-/KRT20-), null/double negative (non-luminal/non-basal). These three categories were meaningful in terms of overall cancer-specific survival (p < 0.0001) or when classified as conventional urothelial carcinoma and variant histology urothelial carcinoma (p < 0.0001), NMIBC vs. MIBC (p < 0.001), or by AJCC stage category Ta (p = 0.0012) and T1 (p < 0.0001) but did not reach significance in T2-T4 (p = 0.563). PD-L1 expression (low vs. high) was also different according to molecular subtype, with high PD-L1 expression mostly seen in basal and null subtypes and carcinomas with variant histology (p = 0.002). Additionally, the luminal subtype was enriched in NMIBC with favorable cancer-specific survival (p < 0.0001). In contrast, basal and null subtypes resulted in aggressive MIBC tumors with shorter cancer-specific survival (p < 0.0001), some of which presented variant histology. In conclusion, a comprehensive evaluation of a gene classifier related to molecular taxonomy using NanoString technology is feasible. Therefore, it might represent an accessible and affordable tool in this rapidly expanding area of precision genomics.

Fin56-induced ferroptosis is supported by autophagy-mediated GPX4 degradation and functions synergistically with mTOR inhibition to kill bladder cancer cells

Ferroptosis is a form of regulated cell death that emerges to be relevant for therapy-resistant and dedifferentiating cancers. Although several lines of evidence suggest that ferroptosis is a type of autophagy-dependent cell death, the underlying molecular mechanisms remain unclear. Fin56, a type 3 ferroptosis inducer, triggers ferroptosis by promoting glutathione peroxidase 4 (GPX4) protein degradation via a not fully understood pathway. Here, we determined that Fin56 induces ferroptosis and autophagy in bladder cancer cells and that Fin56-triggered ferroptosis mechanistically depends on the autophagic machinery. Furthermore, we found that autophagy inhibition at different stages attenuates Fin56-induced oxidative stress and GPX4 degradation. Moreover, we investigated the effects of Fin56 in combination with Torin 2, a potent mTOR inhibitor used to activate autophagy, on cell viability. We found that Fin56 synergizes with Torin 2 in cytotoxicity against bladder cancer cells. Collectively, our findings not only support the concept that ferroptosis is a type of autophagy-dependent cell death but imply that the combined application of ferroptosis inducers and mTOR inhibitors is a promising approach to improve therapeutic options in the treatment of bladder cancer.

Diagnostic and prognostic implications of a three-antibody molecular subtyping algorithm for non-muscle invasive bladder cancer

Intrinsic molecular subtypes may explain marked variation between bladder cancer patients in prognosis and response to therapy. Complex testing algorithms and little attention to more prevalent, early‐stage (non‐muscle invasive) bladder cancers (NMIBCs) have hindered implementation of subtyping in clinical practice. Here, using a three‐antibody immunohistochemistry (IHC) algorithm, we identify the diagnostic and prognostic associations of well‐validated proteomic features of basal and luminal subtypes in NMIBC. By IHC, we divided 481 NMIBCs into basal (GATA3⁻/KRT5⁺) and luminal (GATA3⁺/KRT5 variable) subtypes. We further divided the luminal subtype into URO (p16 low), URO‐KRT5⁺ (KRT5⁺), and genomically unstable (GU) (p16 high) subtypes. Expression thresholds were confirmed using unsupervised hierarchical clustering. Subtypes were correlated with pathology and outcomes. All NMIBC cases clustered into the basal/squamous (basal) or one of the three luminal (URO, URO‐KRT5⁺, and GU) subtypes. Although uncommon in this NMIBC cohort, basal tumors (3%, n = 16) had dramatically higher grade (100%, n = 16, odds ratio [OR] = 13, relative risk = 3.25) and stage, and rapid progression to muscle invasion (median progression‐free survival = 35.4 months, p = 0.0001). URO, the most common subtype (46%, n = 220), showed rapid recurrence (median recurrence‐free survival [RFS] = 11.5 months, p = 0.039) compared to its GU counterpart (29%, n = 137, median RFS = 16.9 months), even in patients who received intravesical immunotherapy (p = 0.049). URO‐KRT5⁺ tumors (22%, n = 108) were typically low grade (66%, n = 71, OR = 3.7) and recurred slowly (median RFS = 38.7 months). Therefore, a simple immunohistochemical algorithm can identify clinically relevant molecular subtypes of NMIBC. In routine clinical practice, this three‐antibody algorithm may help clarify diagnostic dilemmas and optimize surveillance and treatment strategies for patients.

Bladder Cancer-related microRNAs With In Vivo Efficacy in Preclinical Models

Progressive and metastatic bladder cancer remain difficult to treat. In this review, we critique seven up-regulated and 25 down-regulated microRNAs in order to identify new therapeutic entities and corresponding targets. These microRNAs were selected with respect to their efficacy in bladder cancer-related preclinical in vivo models. MicroRNAs and related targets interfering with chemoresistance, cell-cycle, signaling, apoptosis, autophagy, transcription factor modulation, epigenetic modification and metabolism are described. In addition, we highlight microRNAs targeting transmembrane receptors and secreted factors. We discuss druggability issues for the identified targets.

Basal and Luminal Molecular Subtypes in Naturally-Occurring Canine Urothelial Carcinoma are Associated with Tumor Immune Signatures and Dog Breed

BACKGROUND

Improved therapies are needed for patients with invasive urothelial carcinoma (InvUC). Tailoring treatment to molecular subtypes holds promise, but requires further study, including studies in pre-clinical animal models. Naturally-occurring canine InvUC harbors luminal and basal subtypes, mimicking those observed in humans, and could offer a relevant model for the disease in people.

OBJECTIVE

To further validate the canine InvUC model, clinical and tumor characteristics associated with luminal and basal subtypes in dogs were determined, with comparison to findings from humans.

METHODS

RNA sequencing (RNA-seq) analyses were performed on 56 canine InvUC tissues and bladder mucosa from four normal dogs. Data were aligned to CanFam 3.1, and differentially expressed genes identified. Data were interrogated with panels of genes defining luminal and basal subtypes, immune signatures, and other tumor features. Subject and tumor characteristics, and outcome data were obtained from medical records.

RESULTS

Twenty-nine tumors were classified as luminal and 27 tumors as basal subtype. Basal tumors were strongly associated with immune infiltration (OR 52.22, 95%CI 4.68-582.38, P = 0.001) and cancer progression signatures in RNA-seq analyses, more advanced clinical stage, and earlier onset of distant metastases in exploratory analyses (P = 0.0113). Luminal tumors were strongly associated with breeds at high risk for InvUC (OR 0.06, 95%CI 0.01 -0.37, P = 0.002), non-immune infiltrative signatures, and less advanced clinical stage.

CONCLUSIONS

Dogs with InvUC could provide a valuable model for testing new treatment strategies in the context of molecular subtype and immune status, and the search for germline variants impacting InvUC onset and subtype.

HYAL4-V1/Chondroitinase (Chase) Drives Gemcitabine Resistance and Predicts Chemotherapy Failure in Patients with Bladder Cancer

PURPOSE

Gemcitabine-based chemotherapy regimens are first-line for several advanced cancers. Because of better tolerability, gemcitabine + cisplatin is a preferred neoadjuvant, adjuvant, and/or palliative chemotherapy regimen for advanced bladder cancer. Nevertheless, predicting treatment failure and overcoming resistance remain unmet clinical needs. We discovered that splice variant (V1) of HYAL-4 is a first-in-class eukaryotic chondroitinase (Chase), and CD44 is its major substrate. V1 is upregulated in bladder cancer and drives a malignant phenotype. In this study, we investigated whether V1 drives chemotherapy resistance.

EXPERIMENTAL DESIGN

V1 expression was measured in muscle-invasive bladder cancer (MIBC) specimens by qRT-PCR and IHC. HYAL-4 wild-type (Wt) and V1 were stably expressed or silenced in normal urothelial and three bladder cancer cell lines. Transfectants were analyzed for chemoresistance and associated mechanism in preclinical models.

RESULTS

V1 levels in MIBC specimens of patients who developed metastasis, predicted response to gemcitabine + cisplatin adjuvant/salvage treatment and disease-specific mortality. V1-expressing bladder cells were resistant to gemcitabine but not to cisplatin. V1 expression neither affected gemcitabine influx nor the drug-efflux transporters. Instead, V1 increased gemcitabine metabolism and subsequent efflux of difluorodeoxyuridine, by upregulating cytidine deaminase (CDA) expression through increased CD44-JAK2/STAT3 signaling. CDA inhibitor tetrahydrouridine resensitized V1-expressing cells to gemcitabine. While gemcitabine (25-50 mg/kg) inhibited bladder cancer xenograft growth, V1-expressing tumors were resistant. Low-dose combination of gemcitabine and tetrahydrouridine abrogated the growth of V1 tumors with minimal toxicity.

CONCLUSIONS

V1/Chase drives gemcitabine resistance and potentially predicts gemcitabine + cisplatin failure. CDA inhibition resensitizes V1-expressing tumors to gemcitabine. Because several chemotherapy regimens include gemcitabine, our study could have broad significance.

The Role of Molecular Imaging in a Muscle-Invasive Bladder Cancer Patient: A Narrative Review in the Era of Multimodality Treatment

Diagnostic imaging in bladder cancer plays an important role since it is needed from pretreatment staging to follow-up, but a morphological evaluation performed with both CT and MRI showed low sensitivities and specificities in detecting pathologic lymph nodes, due to the occurrence of false positive results. Implementation of functional information provided by PET/CT could be a determinant in the management of patients with muscle-invasive bladder cancer. A focus on the role of ¹⁸F-FDG PET/CT and alternative tracers in patients with muscle-invasive bladder cancer is provided in this analysis in order to outline its potential applications in staging settings and response evaluation after neoadjuvant chemotherapy.

Gene Targeting in Disease Networks

Profiling of whole transcriptomes has become a cornerstone of molecular biology and an invaluable tool for the characterization of clinical phenotypes and the identification of disease subtypes. Analyses of these data are becoming ever more sophisticated as we move beyond simple comparisons to consider networks of higher-order interactions and associations. Gene regulatory networks (GRNs) model the regulatory relationships of transcription factors and genes and have allowed the identification of differentially regulated processes in disease systems. In this perspective, we discuss gene targeting scores, which measure changes in inferred regulatory network interactions, and their use in identifying disease-relevant processes. In addition, we present an example analysis for pancreatic ductal adenocarcinoma (PDAC), demonstrating the power of gene targeting scores to identify differential processes between complex phenotypes, processes that would have been missed by only performing differential expression analysis. This example demonstrates that gene targeting scores are an invaluable addition to gene expression analysis in the characterization of diseases and other complex phenotypes.

Molecular pathology of urothelial carcinoma

The current personalized oncology era has witnessed significant efforts to integrate clinical, pathological, and molecular classifications. The growing need for molecular biomarkers to feed personalized oncology, together with the unprecedented wealth of knowledge on the molecular basis of bladder cancer, has led to a novel approach to this disease, incorporating molecularly generated data in clinical practice for locally advanced or metastatic disease. Translational research allows a better understanding of the early events in the development of urothelial carcinoma in the urinary bladder. Thus, mutations in the KMT2D and KDM6A chromatin-modifying genes confer competitive advantages that drive cells to colonize larger regions of the urothelium. Additional mutations in TP53, PIK3CA, FGFR3, or RB1 genes then trigger the process of malignant transformation in the urothelium. In the current review, we provide an overview of what could be the expected transition from the morphology-based classification to a combined, molecularly enriched reporting of clinically meaningful parameters aiming to promote personalized oncology of urothelial carcinoma.

TNM staging towards a personalized approach in metastatic urothelial carcinoma: what will the future be like?-a narrative review

The American Joint Committee of Cancer (AJCC) tumor-node-metastasis (TNM) classification, with its periodical updates and modifications, has represented and still represents the basis of cancer staging. The historical, long-standing limitations of anatomic-based TNM staging have been recently “threatened” by the impressive amount of data derived from molecular analyses, which have led to an unprecedented level of understanding of cancer genomics. In fact, current era of personalized oncology has witnessed important efforts towards the integration between clinical, anatomical and molecular features; however, despite the promises, personalized oncology faces many obstacles, due to the complex relationship between tumor biomarkers, previously unknown cancer subtypes and clinical and anatomical characteristics. With regard to urothelial carcinoma (UC), the characterization of tumors in large cohorts of patients has provided important information concerning genetic alterations, revealing the presence of biologically relevant subtypes of UC. In the current review, we will provide an overview regarding this recent “translation” from the anatomic-based TNM to a novel horizon, aiming at further “tailoring” personalized oncology, especially focusing on recently published data about the molecular landscape of UC with its therapeutic and prognostic implications.

Comprehensive pathological assessment of histological subtypes, molecular subtypes based on immunohistochemistry, and tumor-associated immune cell status in muscle-invasive bladder cancer

Molecular assessments of muscle-invasive bladder cancer (MIBC) have yielded several molecular categorizations associated with basal and luminal subtypes or tumor-associated immune cell status (TAICs). However, the histological relationships among histological subtypes, molecular subtypes, and TAICs and their clinical implications remain unclear. Thus, we aimed to evaluate the histological associations among these factors and their clinicopathological outcomes. We retrospectively analyzed 106 patients with MIBC who underwent radical cystectomy. The histological subtypes and TAICs were evaluated with hematoxylin and eosin staining, while the basal and luminal molecular subtypes were determined by immunohistochemical expression of cytokeratin (CK) 5/6, CK14, CK20, GATA3 and uroplakin II. Urothelial carcinoma with squamous differentiation and the sarcomatoid variant were highly associated with the basal subtype (P < 0.001 and P = 0.04, respectively). Additionally, high TAICs were significantly correlated with the basal subtype (P < 0.001). Although there was no significant difference in the cancer-specific survival (CSS) rate between molecular subtypes (P = 0.295), TAICs significantly discriminated CSS rates (P < 0.001). Furthermore, the combination of molecular subtypes and TAICs significantly stratified cancer-specific mortality rates. In conclusion, a comprehensive pathological evaluation of histological subtypes, molecular subtypes, and TAICs is feasible and can influence the oncological outcome.

An overview of patients with urothelial bladder cancer over the past two decades: a Surveillance, Epidemiology, and End Results (SEER) study

Background

To explore the overall trends of incidence rate (IR), mortality and survival outcomes of patients with urothelial bladder cancer (UBC) over the past two decades.

Methods

Patients diagnosed with UBC from 1993 to 2012 were extracted from the Surveillance, Epidemiology and End Result (SEER) 18 database. Baseline characteristics and treatment types of included patients were collected retrospectively. Moreover, the age-adjusted IRs and annual percent changes (APCs) were obtained. Afterwards, we calculated the standardized mortality ratios (SMRs) for bladder cancer (BC), cardiovascular disease (CVD) and all-cause mortality by comparing UBC cases with the general population. Finally, survival outcomes of UBC patients were analyzed and compared.

Results

A total of 220,405 UBC patients were identified, including 167,036 (75.79%) male patients and 53,369 (24.21%) female patients, with an average age of 70.84 years old. Most patients were White (89.85%), with older age (71.67%, >65 years old), lower T stage diseases (78.11%, < T2) and lower median household income (55.37%). When compared with patients diagnosed between 1993 and 2002, those diagnosed between 2003 and 2012 had older age (mean: 71.15 vs. 70.16 years old, P<0.001), higher proportion of men (76.22% vs. 74.83%, P<0.001) and lower median household income (56.69% vs. 52.50%, P<0.01). Overall, the IR of UBC increased slightly before 2003 and maintained a stable trend of about 20 per 100,000 person-years after 2003. Additionally, CVD was recognized as an important cause of death (COD) of UBC patients. UBC patients were 44.5 times more likely to die of CVD when compared with the general population. Furthermore, the 3-, 5- and 10-year overall survival (OS) and cancer-specific survival (CSS) rates were 0.709, 0.609 and 0.421, and 0.861, 0.831 and 0.789, respectively. Finally, survival outcomes between patients diagnosed in the two periods (1993–2002 vs. 2003–2012) were not significantly different.

Conclusions

The IR of UBC increased slightly before 2003 and remained stable after 2003. UBC patients had higher CVD burden than the general population. Hence, cardiovascular health should be emphasized to reduce mortality after UBC diagnosis. Lastly, survival outcomes of UBC patients in the last two decades showed no significant difference.

[Molecular subtypes of urothelial carcinoma of the bladder-background and clinical relevance]

Advanced and metastatic stages of bladder cancer are associated with a poor prognosis. Therapy options are currently limited to systemic therapy with chemo- and immunotherapeutics. In order to improve individual therapy and especially to achieve a more favorable prognosis for these patients, intrinsic molecular subtypes have recently been identified in urothelial carcinoma of the bladder. This review article presents the latest developments, background, and clinical relevance of molecular subtypes in urothelial carcinoma of the bladder. The existing literature and current study data were analyzed to present and evaluate the different molecular classification systems. A focus was placed on the possible therapeutic implications of these molecular subtypes. Although promising progress has been made in the molecular subtyping of urothelial carcinoma, this classification has not yet found its way into clinical application. Multicenter prospective studies with standardized study protocols are still lacking. Previous studies differ in molecular markers, sample collection and preparation procedures, and analytical protocols. Standardization is urgently needed before guidelines can be established and targeted treatment regimens implemented. In principle, the aim should be to develop a stable and as simple as possible methodology, enabling personalized treatment based on molecular subtypes to be broadly applied, and not just in specialized expert centers.

Metabolomic and lipidomic approaches to identify biomarkers for bladder cancer and interstitial cystitis (Review)

The discovery, introduction and clinical use of prognostic and diagnostic biomarkers has significantly improved outcomes for patients with various illnesses, including bladder cancer (BC) and other bladder-related diseases, such as benign bladder dysfunction and interstitial cystitis (IC). Several sensitive and noninvasive clinically relevant biomarkers for BC and IC have been identified. Metabolomic- and lipidomic-based biomarkers have notable clinical potential in improving treatment outcomes for patients with cancer; however, there are also some noted limitations. This review article provides a short and concise summary of the literature on metabolomic and lipidomic biomarkers for BC and IC, focusing on the possible clinical utility of profiling metabolic alterations in BC and IC.

Development of a prognostic signature for bladder cancer based on immune-related genes

Background

Although the prognosis of patients with bladder cancer (BC) has improved significantly with the use of multimodal therapy, reliable prognostic biomarkers are still urgently needed due to the heterogeneity of tumors. Our aim was to develop an individualized immune-related gene pair (IRGP) signature that could precisely predict prognosis in BC patients.

Methods

Gene expression profiles and corresponding clinical information were collected from eight microarray data sets and one RNA-Seq data set.

Results

Among 1,811 immune genes, a 30-IRGP signature consisting of 52 unique genes was generated in the training cohort, which significantly stratified patients into low- and high-risk groups in terms of overall survival. In the testing and validation cohorts, the IRGP signature was also associated with patient prognosis in the univariate and multivariate Cox regression analyses. Several biological processes, including the immune response, chemotaxis, and the inflammatory response, were enriched among genes in the IRGP signature. When the signature was integrated with the TNM stage, an IRGP nomogram was developed and showed improved prognostic accuracy relative to the IRGP signature alone.

Conclusions

In short, we identified a robust IRGP signature for estimating overall survival in BC patients that could also be used as a promising biomarker for identifying high-risk patients for individualized therapy.

Pure high-grade papillary urothelial bladder cancer: a luminal-like subgroup with potential for targeted therapy

PURPOSE

Non-invasive high-grade (HG) bladder cancer is a heterogeneous disease that is characterized insufficiently. First-line Bacillus Calmette-Guérin instillation fails in a substantial amount of cases and alternative bladder-preserving treatments are limited, underlining the need to promote a further molecular understanding of non-invasive HG lesions. Here, we characterized pure HG papillary urothelial bladder cancer (pure pTa HG), a potential subgroup of non-invasive HG bladder carcinomas, with regard to molecular subtype affiliation and potential for targeted therapy.

METHODS

An immunohistochemistry panel comprising luminal (KRT20, ERBB2, ESR2, GATA3) and basal (KRT5/6, KRT14) markers as well as p53 and FGFR3 was used to analyze molecular subtype affiliations of 78 pure pTa HG/papillary pT1(a) HG samples. In 66 of these, ERBB2 fluorescence in situ hybridization was performed. Additionally, targeted sequencing (31 genes) of 19 pTa HG cases was conducted, focusing on known therapeutic targets or those described to predict response to targeted therapies noted in registered clinical trials or that are already approved.

RESULTS

We found that pure pTa HG/papillary pT1(a) HG lesions were characterized by a luminal-like phenotype associated with frequent (58% of samples) moderate to high ERBB2 protein expression, rare FGFR3 alterations on genomic and protein levels, and a high frequency (89% of samples) of chromatin-modifying gene alterations. Of note, 95% of pTa HG/papillary pT1 HG cases harbored at least one potential druggable genomic alteration.

CONCLUSIONS

Our data should help guiding the selection of targeted therapies for investigation in future clinical trials and, additionally, may provide a basis for prospective mechanistic studies of pTa HG pathogenesis.

The therapeutic and prognostic implications of molecular biomarkers in urothelial carcinoma

Urothelial cell carcinoma (UCC) of the bladder and upper urinary tract is a heterogeneous disease with distinct biologic features resulting in different clinical behaviors. Bladder cancer (BC) is classified into non-muscle invasive BC (NMIBC) and muscle invasive BC (MIBC). NMIBC is associated with high recurrence rates and risk of progression to invasive disease, whereas MIBC is complicated by systemic recurrence after radical cystectomy because of the limited efficacy of available therapies. UCC of the upper urinary tract (UUT-UCC) is a rare but aggressive urologic cancer characterized by multifocality, local recurrence, and metastasis. Conventional histopathologic evaluation of UCC, including tumor stage and grade, cannot accurately predict the behavior of BC and UUT-UCC. Recent clinical and preclinical studies aimed at understanding the molecular landscape of UCC have provided insight into molecular subtyping, inter- or intratumoral heterogeneity, and potential therapeutic targets. Combined analysis of molecular markers and standard pathological features may improve risk stratification and help monitor tumor progression and treatment response, ultimately improving patient outcomes. This review discusses prognostic and therapeutic biomarkers for BC and UUT-UCC, and describes recent advances in molecular stratification that may guide prognosis, patient stratification, and treatment selection.

Building a Canadian Translational Bladder Cancer Research Network

Bladder cancer research has historically lagged behind efforts in other disease sites with substantial underfunding relative to the heavy morbidity and mortality suffered by patients. Alongside increasing advocacy however, more recent advances in our understanding of the molecular biology of bladder cancer has ushered in a period of renaissance with exciting prospects for novel, precise diagnostics and therapeutics. Given significant and diverse assets within the research community across Canada, an inaugural translational research forum was convened to identify research gaps and strengths, and to formalize investigational themes that would be apposite for multi-institutional collaboration. The virtual meeting brought together a multi-disciplinary network of genitourinary cancer researchers, including clinicians and basic scientists, and entailed detailed environmental scans of the Canadian clinical and translational research landscape as well as selected “elevator pitches” of potential research themes. The results of these discussions are detailed herein and have provided the impetus to formalize the Canadian Bladder Cancer Research Network (CBCRN). Working groups have been created to focus future multi-institutional collaborations in four inter-related initiatives: biomarker development, epigenetic targeting, immuno-oncology and the microbiome.

Evolution of Urothelial Bladder Cancer in the Context of Molecular Classifications

Bladder cancer is a heterogeneous disease that is not depicted by current classification systems. It was originally classified into non-muscle invasive and muscle invasive. However, clinically and genetically variable tumors are summarized within both classes. A definition of three groups may better account for the divergence in prognosis and probably also choice of treatment. The first group represents mostly non-invasive tumors that reoccur but do not progress. Contrarily, the second group represent non-muscle invasive tumors that likely progress to the third group, the muscle invasive tumors. High throughput tumor profiling improved our understanding of the biology of bladder cancer. It allows the identification of molecular subtypes, at least three for non-muscle invasive bladder cancer (Class I, Class II and Class III) and six for muscle-invasive bladder cancer (luminal papillary, luminal non-specified, luminal unstable, stroma-rich, basal/squamous and neuroendocrine-like) with distinct clinical and molecular phenotypes. Molecular subtypes can be potentially used to predict the response to treatment (e.g., neoadjuvant chemotherapy and immune checkpoint inhibitors). Moreover, they may allow to characterize the evolution of bladder cancer through different pathways. However, to move towards precision medicine, the understanding of the biological meaning of these molecular subtypes and differences in the composition of cell subpopulations will be mandatory.

Immunohistochemistry-Based Taxonomical Classification of Bladder Cancer Predicts Response to Neoadjuvant Chemotherapy

BACKGROUND

Platinum-based neoadjuvant chemotherapy (NAC) increases the survival of patients with organ-confined urothelial bladder cancer (UBC). In retrospective studies, patients with basal/squamous (BASQ)-like tumors present with more advanced disease and have worse prognosis. Transcriptomics-defined tumor subtypes are associated with response to NAC.

AIM

To investigate whether immunohistochemical (IHC) subtyping predicts NAC response.

METHODS

Patients with muscle-invasive UBC having received platinum-based NAC were identified. Tissue microarrays were used to type tumors for KRT5/6, KRT14, GATA3, and FOXA1.

OUTCOMES

progression-free survival and disease-specific survival; univariable and multivariate Cox regression models were applied.

RESULTS

We found a very high concordance between mRNA and protein expression. Using IHC-based hierarchical clustering, we classified 126 tumors in three subgroups: BASQ-like (FOXA1/GATA3 low; KRT5/6/14 high), Luminal-like (FOXA1/GATA3 high; KRT5/6/14 low), and mixed-cluster (FOXA1/GATA3 high; KRT5/6 high; KRT14 low). Applying multivariable analyses, patients with BASQ-like tumors were more likely to achieve a pathological response to NAC (OR 3.96; p = 0.017). The clinical benefit appeared reflected in the lack of significant survival differences between patients with BASQ-like and luminal tumors.

CONCLUSIONS

Patients with BASQ-like tumors-identified through simple and robust IHC-have a higher likelihood of undergoing a pathological complete response to NAC. Prospective validation is required.

Estrogen receptors in urogenital schistosomiasis and bladder cancer: Estrogen receptor alpha-mediated cell proliferation

Estrogen-like metabolites have been identified in S. haematobium, the helminth parasite that causes urogenital schistosomiasis (UGS) and in patients´ blood and urine during UGS. Estrogen receptor (ER) activation is enriched in the luminal molecular subtype bladder cancer (BlaCa). To date, the significance of ER to these diseases remains elusive. We evaluated ERα and ERβ expression in UGS-related BlaCa (n = 27), UGS-related non-malignant lesions (n = 35), and noninfected BlaCa (n = 80). We investigated the potential of ERα to recognize S. haematobium-derived metabolites by docking and molecular dynamics simulations and studied ERα modulation in vitro using 3 BlaCa cell lines, T24, 5637 and HT1376. ERα was expressed in tumor and stromal cells in approximately 20% noninfected cases and in 30% of UGS-related BlaCa, predominantly in the epithelial cells. Overall, ERα expression was associated with features of tumor aggressiveness such as high proliferation and p53 positive expression. ERα expression correlated with presence of schistosome eggs. ERβ was widely expressed in both cohorts but weaker in UGS-related cases. molecular dynamics simulations of the 4 most abundant S. haematobium-derived metabolites revealed that smaller metabolites have comparable affinity for the ERα active state than 17β-estradiol, while the larger metabolites present higher affinity. Our in vitro findings suggested that ERα activation promotes proliferation in ERα expressing BlaCa cells and that this can be reverted with anti-estrogenic therapy. In summary, we report differential ER expression between UGS-related BlaCa and noninfected BlaCa and provide evidence supporting a role of active ERα during UGS and UGS-induced carcinogenesis.

CCL2 Expression in Tumor Cells and Tumor-Infiltrating Immune Cells Shows Divergent Prognostic Potential for Bladder Cancer Patients Depending on Lymph Node Stage

Bladder cancer (BCa) is the ninth most commonly diagnosed cancer worldwide. Although there are several well-established molecular and immunological classifications, markers for tumor cells and immune cells that are associated with prognosis are still needed. The chemokine CC motif ligand 2 (CCL2) could be such a marker. We analyzed the expression of CCL2 by immunohistochemistry (IHC) in 168 muscle invasive BCa samples using a tissue microarray. Application of a single cut-off for the staining status of tumor cells (TCs; positive vs. negative) and immune cells (ICs; ≤6% of ICs vs. >6% of ICs) revealed 57 cases (33.9%) and 70 cases (41.7%) with CCL2-positive TCs or ICs, respectively. IHC results were correlated with clinicopathological and survival data. Positive CCL2 staining in TCs was associated with shorter overall survival (OS), disease-specific survival (DSS), and relapse-free survival (RFS) (p = 0.004, p = 0.036, and p = 0.047; log rank test) and appeared to be an independent prognostic factor for OS (RR = 1.70; p = 0.007; multivariate Cox’s regression analysis). In contrast, positive CCL2 staining in the ICs was associated with longer OS, DSS, and RFS (p = 0.032, p = 0.001, and p = 0.001; log rank test) and appeared to be an independent prognostic factor for DSS (RR = 1.77; p = 0.031; multivariate Cox’s regression analysis). Most interestingly, after separating the patients according to their lymph node status (N0 vs. N1+2), CCL2 staining in the ICs was differentially associated with prognosis. In the N0 group, CCL2 positivity in the ICs was a positive independent prognostic factor for OS (RR = 1.99; p = 0.014), DSS (RR = 3.17; p = 0.002), and RFS (RR = 3.10; p = 0.002), whereas in the N1+2 group, CCL2 positivity was a negative independent factor for OS (RR = 3.44; p = 0.019)) and RFS (RR = 4.47; p = 0.010; all multivariate Cox’s regression analyses). In summary, CCL2 positivity in TCs is a negative prognostic factor for OS, and CCL2 can mark ICs that are differentially associated with prognosis depending on the nodal stage of BCa patients. Therefore, CCL2 staining of TCs and ICs is suggested as a prognostic biomarker for BCa patients.

RNAseq expression patterns of canine invasive urothelial carcinoma reveal two distinct tumor clusters and shared regions of dysregulation with human bladder tumors

BACKGROUND

Invasive urothelial carcinoma (iUC) is highly similar between dogs and humans in terms of pathologic presentation, molecular subtypes, response to treatment and age at onset. Thus, the dog is an established and relevant model for testing and development of targeted drugs benefiting both canine and human patients. We sought to identify gene expression patterns associated with two primary types of canine iUC tumors: those that express a common somatic mutation in the BRAF gene, and those that do not.

METHODS

We performed RNAseq on tumor and normal tissues from pet dogs. Analysis of differential expression and clustering, and positional and individual expression was used to develop gene set enrichment profiles distinguishing iUC tumors with and without BRAFV595E mutations, as well as genomic regions harboring excessive numbers of dysregulated genes.

RESULTS

We identified two expression clusters that are defined by the presence/absence of a BRAFV595E (BRAFV600E in humans) somatic mutation. BRAFV595E tumors shared significantly more dysregulated genes than BRAF wild-type tumors, and vice versa, with 398 genes differentiating the two clusters. Key genes fall into clades of limited function: tissue development, cell cycle regulation, immune response, and membrane transport. The genomic site with highest number of dysregulated genes overall lies in a locus corresponding to human chromosome 8q24, a region frequently amplified in human urothelial cancers.

CONCLUSIONS

These data identify critical sets of genes that are differently regulated in association with an activating mutation in the MAPK/ERK pathway in canine iUC tumors. The experiments also highlight the value of the canine system in identifying expression patterns associated with a common, shared cancer.

Biomarkers for Early Cancer Diagnosis: Prospects for Success through the Lens of Tumor Genetics

Thousands of candidate cancer biomarkers have been proposed, but so far, few are used in cancer screening. Failure to implement these biomarkers is attributed to technical and design flaws in the discovery and validation phases, but a major obstacle stems from cancer biology itself. Oncogenomics has revealed broad genetic heterogeneity among tumors of the same histology and same tissue (or organ) from different patients, while tumors of different tissue origins also share common genetic mutations. Moreover, there is wide intratumor genetic heterogeneity among cells within any single neoplasm. These findings seriously limit the prospects of finding a single biomarker with high specificity for early cancer detection. Current research focuses on developing biomarker panels, with data assessment by machine-learning algorithms. Whether such approaches will overcome the inherent limitations posed by tumor biology and lead to tests with true clinical value remains to be seen.