Toward a Molecular Pathologic Classification of Urothelial Carcinoma

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.

Therapeutic importance and diagnostic function of circRNAs in urological cancers: from metastasis to drug resistance

Circular RNAs (circRNAs) are a member of non-coding RNAs with no ability in encoding proteins and their aberrant dysregulation is observed in cancers. Their closed-loop structure has increased their stability, and they are reliable biomarkers for cancer diagnosis. Urological cancers have been responsible for high mortality and morbidity worldwide, and developing new strategies in their treatment, especially based on gene therapy, is of importance since these malignant diseases do not respond to conventional therapies. In the current review, three important aims are followed. At the first step, the role of circRNAs in increasing or decreasing the progression of urological cancers is discussed, and the double-edged sword function of them is also highlighted. At the second step, the interaction of circRNAs with molecular targets responsible for urological cancer progression is discussed, and their impact on molecular processes such as apoptosis, autophagy, EMT, and MMPs is highlighted. Finally, the use of circRNAs as biomarkers in the diagnosis and prognosis of urological cancer patients is discussed to translate current findings in the clinic for better treatment of patients. Furthermore, since circRNAs can be transferred to tumor via exosomes and the interactions in tumor microenvironment provided by exosomes such as between macrophages and cancer cells is of importance in cancer progression, a separate section has been devoted to the role of exosomal circRNAs in urological tumors.

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.

Molecular Pathology of Urothelial Carcinoma

Urothelial carcinoma is characterized by the presence of a wide spectrum of histopathologic features and molecular alterations that contribute to its morphologic and genomic heterogeneity. It typically harbors high rates of somatic mutations with considerable genomic and transcriptional complexity and heterogeneity that is reflective of its varied histomorphologic and clinical features. This review provides an update on the recent advances in the molecular characterization and novel molecular taxonomy of urothelial carcinoma and variant histologies.

Prognostic Value of P63 Expression in Muscle-Invasive Bladder Cancer and Association with Molecular Subtypes-Preliminary Report

There is an ongoing need for biomarkers that could reliably predict the outcome of BC and that could guide the management of this disease. In this setting, we aimed to explore the prognostic value of the transcription factor P63 in patients with muscle-invasive bladder cancer (MIBC) having undergone radical cystectomy. The correlation between P63 expression and clinicopathological features (tumor stage, nodes involvement, patterns of muscularis propria invasion, papillary architecture, anaplasia, concomitant carcinoma in situ, lymphovascular invasion, perineural invasion, necrosis) and molecular subtyping (basal and luminal type tumors) was tested in 65 radical cystectomy specimens and matched with cancer-specific survival (CSS) and overall survival (OS). P63-negative tumors displayed significantly higher rates of pattern 2 of muscularis propria invasion (50% vs. 14%, p = 0.002) and variant histology (45% vs. 19%, p = 0.022) compared to P63-positive ones. According to the combined expression of CK5/6 and CK20 (Algorithm #1), P63-positive and P63-negative tumors were mostly basal-like and double-negative, respectively (p = 0.004). Using Algorithm #2, based on the combined expression of CK5/6 and GATA3, the vast majority of tumors were luminal overall and in each group (p = 0.003). There was no significant difference in CSS and OS between P63-positive and P63-negative tumors, but the former featured a trend towards longer OS. Though associated with pathological features harboring negative prognostic potential, P63 status as such failed to predict CSS and OS. That said, it may contribute to better molecular subtyping of MIBC.

Reconstructing disease dynamics for mechanistic insights and clinical benefit

Diseases change over time, both phenotypically and in their underlying molecular processes. Though understanding disease progression dynamics is critical for diagnostics and treatment, capturing these dynamics is difficult due to their complexity and the high heterogeneity in disease development between individuals. We present TimeAx, an algorithm which builds a comparative framework for capturing disease dynamics using high-dimensional, short time-series data. We demonstrate the utility of TimeAx by studying disease progression dynamics for multiple diseases and data types. Notably, for urothelial bladder cancer tumorigenesis, we identify a stromal pro-invasion point on the disease progression axis, characterized by massive immune cell infiltration to the tumor microenvironment and increased mortality. Moreover, the continuous TimeAx model differentiates between early and late tumors within the same tumor subtype, uncovering molecular transitions and potential targetable pathways. Overall, we present a powerful approach for studying disease progression dynamics-providing improved molecular interpretability and clinical benefits for patient stratification and outcome prediction.

The Management of Bacillus Calmette-Guérin (BCG) Failure in High-Risk Non-muscle Invasive Bladder Cancer: A Review Article

Non-muscle invasive bladder cancer (NMIBC) is a common urological malignancy, and bacillus Calmette-Guérin (BCG) therapy is the gold standard treatment in intermediate and high-risk groups. However, BCG failure occurs in a significant proportion of patients, emphasizing the need for effective alternative treatment modalities to address this burden. These treatments include immunotherapy, enhanced drug delivery, targeted therapy, device-assisted chemotherapy, vaccine therapy, and gene therapy, which show varying degrees of safety and efficacy. The objective of this review is to summarize the current evidence and ongoing research on these emerging therapies, offering insight into their potential for improving patient outcomes and quality of life. Although radical cystectomy remains the standard of care for high-risk NMIBC patients unresponsive to BCG, novel treatment modalities hold promise for the future management of this challenging patient population.

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.

The Lund taxonomy for bladder cancer classification - from gene expression clustering to cancer cell molecular phenotypes, and back again

Treatment of bladder cancer patients depends on precise diagnosis. Molecular subtyping by gene expression profiling may contribute substantially to subclassification of bladder cancer. Several classification systems have been proposed. Most of these base their classification on whole biopsy features, and molecular subtypes are therefore often defined by a combination of features from the cancer cells as well as infiltrating noncancer cells. This makes the link to what is seen at the cancer cell level unclear. The aim of the Lund taxonomy (LundTax) has been to align gene expression-level classification with immunohistochemical classification to identify cancer cell phenotypes independent of infiltration and proliferation. A systematic approach was used in which gene expression clusters were validated and adjusted by immunohistochemistry using markers expressed only by the cancer cells. This review provides a rationale for defining molecular subtypes and a step-by-step description of the development of the LundTax with motivations for each modification and extension. As the cancer cell phenotype defined by gene expression profiling corresponds with the immunohistochemistry of cancer cells, the LundTax represents a harmonization of the gene expression and immunohistochemical levels. Furthermore, the classification system is independent of pathological stage and is, thus, applicable to all urothelial carcinomas. A unified classification system relevant for both the molecular biologist and pathologist will facilitate systematization of current treatment practices, as well as the development of new treatments. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

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.

HER2 Expression in Bladder Cancer: A Focused View on Its Diagnostic, Prognostic, and Predictive Role

Bladder cancer (BC) is a heterogeneous disease from a molecular, morphological, and clinical standpoint. HER2 is a known oncogene involved in bladder carcinogenesis. Assessing HER2 overexpression as a result of its molecular changes in a routine pathology practice using immunohistochemistry might be a useful adjunct in several scenarios, namely (1) to correctly identify flat urothelial lesions and inverted urothelial lesions in the diagnostic setting; (2) to provide prognostic hints in both non-muscle invasive (NMI) and muscle invasive (MI) tumors, thus supplementing risk stratification tools, especially when evaluating higher-risk tumors such as those with variant morphology; (3) to improve antibody panels as a surrogate marker of BC molecular subtyping. Furthermore, the potential of HER2 as a therapeutic target has been only partly explored so far, in light of the ongoing development of novel target therapies.

Molecular Taxonomy and Immune Checkpoint Therapy in Bladder Cancer

Bladder cancer is a heterogeneous disease, which exhibits a wide spectrum of clinical and pathologic features. Recent genomic studies have revealed that distinct molecular alterations may underlie the diverse clinical behaviors of bladder cancer, leading to a novel molecular classification. The intrinsic molecular subtypes exhibit distinct gene expression signatures and different clinicopathologic features. Genomic alterations also underlie the development of bladder cancer histologic subtypes. Genomic characterization provides new insights to understanding the biology of bladder cancer and improves the diagnosis and treatment of this complex disease. Biomarkers can aid the selection of patients for immune checkpoint therapy.

Current best practice for bladder cancer: a narrative review of diagnostics and treatments

This Seminar presents the current best practice for the diagnosis and management of bladder cancer. The scope of this Seminar ranges from current challenges in pathology, such as the evolving histological and molecular classification of disease, to advances in personalised medicine and novel imaging approaches. We discuss the current role of radiotherapy, surgical management of non-muscle-invasive and muscle-invasive disease, highlight the challenges of treatment of metastatic bladder cancer, and discuss the latest developments in systemic therapy. This Seminar is intended to provide physicians with knowledge of current issues in 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.

Near-Infrared Photoimmunotherapy (NIR-PIT) in Urologic Cancers

Near-infrared photoimmunotherapy (NIR-PIT) is a novel molecularly-targeted therapy that selectively kills cancer cells by systemically injecting an antibody-photoabsorber conjugate (APC) that binds to cancer cells, followed by the application of NIR light that drives photochemical transformations of the APC. APCs are synthesized by selecting a monoclonal antibody that binds to a receptor on a cancer cell and conjugating it to IRDye700DX silica-phthalocyanine dye. Approximately 24 h after APC administration, NIR light is delivered to the tumor, resulting in nearly-immediate necrotic cell death of cancer cells while causing no harm to normal tissues. In addition, NIR-PIT induces a strong immunologic effect, activating anti-cancer immunity that can be further boosted when combined with either immune checkpoint inhibitors or immune suppressive cell-targeted (e.g., regulatory T cells) NIR-PIT. Currently, a global phase III study of NIR-PIT in recurrent head and neck squamous cell carcinoma is ongoing. The first APC and NIR laser systems were approved for clinical use in September 2020 in Japan. In the near future, the clinical applications of NIR-PIT will expand to other cancers, including urologic cancers. In this review, we provide an overview of NIR-PIT and its possible applications in urologic cancers.

Uroplakin II as a single marker for luminal versus basal molecular subtypes in muscle invasive urothelial carcinoma

Bladder cancer is a heterogeneous disease classified into two broad molecular subtype categories, basal and luminal, with critical treatment and prognostic implications. Recent studies have shown the utility of immunohistochemistry in predicting bladder cancer molecular subtypes, with a two-marker approach using GATA3 and CK5/6 showing over 80% reliability. In the current study, we calculated the accuracy of uroplakin II (UPII), a marker of urothelial differentiation, with different scores (0: <1%, 1+: 1-10%, 2+: 10-50%, 3+: >50%) to predict RNA-based luminal versus basal subtypes in a cohort of muscle-invasive bladder cancer-received neoadjuvant chemotherapy followed by radical cystectomy. The 1% cutoff of the UPII stain predicts the luminal subtype with the sensitivity and specificity of 95% and 56%, respectively. With a UPII cutoff of 10%, the sensitivity and specificity were 93% and 81%, respectively, and with a UPII cutoff of 50%, the sensitivity and specificity were 91% and 96%, respectively. The prediction performance of UPII was better than either GATA3 or CK5/6. There was no significant difference in prognoses between UPII 0-2+ and UPII 3+ patients in this cohort. The current study shows that evaluating the staining proportion score of UPII can accurately predict basal and luminal subtypes of muscle-invasive bladder cancer.

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.

Combined miRNA and SERS urine liquid biopsy for the point-of-care diagnosis and molecular stratification of bladder cancer

BACKGROUND

Bladder cancer (BC) has the highest per-patient cost of all cancer types. Hence, we aim to develop a non-invasive, point-of-care tool for the diagnostic and molecular stratification of patients with BC based on combined microRNAs (miRNAs) and surface-enhanced Raman spectroscopy (SERS) profiling of urine.

METHODS

Next-generation sequencing of the whole miRNome and SERS profiling were performed on urine samples collected from 15 patients with BC and 16 control subjects (CTRLs). A retrospective cohort (BC = 66 and CTRL = 50) and RT-qPCR were used to confirm the selected differently expressed miRNAs. Diagnostic accuracy was assessed using machine learning algorithms (logistic regression, naïve Bayes, and random forest), which were trained to discriminate between BC and CTRL, using as input either miRNAs, SERS, or both. The molecular stratification of BC based on miRNA and SERS profiling was performed to discriminate between high-grade and low-grade tumors and between luminal and basal types.

RESULTS

Combining SERS data with three differentially expressed miRNAs (miR-34a-5p, miR-205-3p, miR-210-3p) yielded an Area Under the Curve (AUC) of 0.92 ± 0.06 in discriminating between BC and CTRL, an accuracy which was superior either to miRNAs (AUC = 0.84 ± 0.03) or SERS data (AUC = 0.84 ± 0.05) individually. When evaluating the classification accuracy for luminal and basal BC, the combination of miRNAs and SERS profiling averaged an AUC of 0.95 ± 0.03 across the three machine learning algorithms, again better than miRNA (AUC = 0.89 ± 0.04) or SERS (AUC = 0.92 ± 0.05) individually, although SERS alone performed better in terms of classification accuracy.

CONCLUSION

miRNA profiling synergizes with SERS profiling for point-of-care diagnostic and molecular stratification of BC. By combining the two liquid biopsy methods, a clinically relevant tool that can aid BC patients is envisaged.

News in the classification of WHO 2022 bladder tumors

The fifth-edition of World Health Organization (WHO) Classification of Tumors series for urinary and male genital tract tumors has been published, six years later the fourth-edition. In these years, new treatment approaches have been implemented and new molecular data on urological cancers are known.

Morphology remains the groundwork for taxonomy of the urinary tract tumors. However, a molecular approach to classification of urothelial carcinomas and the management of selected neoplasms with new therapeutic modalities such as immunotherapy are emerging. More data are needed for the application of these advances in routine pathology practice and patient management.

The 2022 World Health Organization (WHO) Classification of Tumors of the Urinary System and Male Genital Organs represents an update in classification on urinary tract tumors. It also offers new insights with regards to the grading of heterogeneous non-invasive urothelial neoplasms, the definition of inverted neoplasms, the grading of invasive urothelial carcinomas, the diversity of morphological appearance of urothelial carcinomas, the definition of precursor lesions and the lineage of differentiation of the tumors.

Reappraisal of HER2 Amplification in High-Grade Urothelial Carcinoma Based on 2018 ASCO/CAP Clinical Practice Guidelines

OBJECTIVES

To examine and compare human epidermal growth factor receptor 2 (HER2) amplification status in high-grade urothelial carcinoma (HGUCa), using both 2013 and 2018 HER2 reporting guidelines for breast carcinoma from the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP).

METHODS

HER2 status by fluorescence in situ hybridization (FISH) assay in 78 cases of HGUCa was compared using 2013 and 2018 HER2 reporting guidelines.

RESULTS

HER2 amplification was observed in 22 (28.2%) of 78 tumors, of which 17 were in group 1, 1 in group 2, and 2 each in groups 3 and 4 (FISH assay, 2018). The remaining 14 HER2-amplified tumors (FISH assay, 2013) became negative, falling into group 2 (FISH assay, 2018) and were either negative or equivocal on immunohistochemistry (IHC, 2018). All FISH-negative tumors (n = 37) using 2013 criteria remained negative (group 5, 2018). FISH-equivocal tumors (2013) were further categorized into HER2 amplified (n = 1) and HER2 negative (n = 4) (2018). Overall, 20 (25.6%) tumors had discordant HER2 FISH results (2018 vs 2013).

CONCLUSIONS

Implementing 2018 guidelines, HER2 amplification decreased from 36 to 22 cases. The group with a HER2/CEP17 ratio of 2 or more and average HER2 copy number less than 4 (group 2) were predominantly negative by IHC, suggesting a biologically distinct group of HGUCa that is different from HER2-amplified tumors, which may not respond to HER2-targeted therapy.

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.

Cytokeratin 5 and cytokeratin 6 expressions are unconnected in normal and cancerous tissues and have separate diagnostic implications

Cytokeratins (CKs) 5 and 6 are functionally unrelated but often analyzed together using bispecific antibodies in diagnostic immunohistochemistry. To better understand the diagnostic utility of CK5 or CK6 alone, tissue microarrays with > 15,000 samples from 120 different tumor types as well as 608 samples of 76 different normal tissues were analyzed by immunohistochemistry. In normal tissues, both CKs occurred in the squamous epithelium; CK5 dominated in basal and CK6 in suprabasal layers. CK5 (not CK6) stained basal cells in various other organs. Within tumors, both CK5 and CK6 were seen in > 95% of squamous cell carcinomas, but other tumor entities showed different results: CK5 predominated in urothelial carcinoma and mesothelioma, but CK6 in adenocarcinomas. Joint analysis of both CK5 and CK6 obscured the discrimination of epithelioid mesothelioma (100% positive for CK5 alone and for CK5/6) from adenocarcinoma of the lung (12.8% positive for CK5 alone; 23.7% positive for CK5/6). CK5 and CK6 expressions were both linked to high grade, estrogen receptor, and progesterone receptor negativity in breast cancer (p < 0.0001 each), grade/stage progression in urothelial cancer (p < 0.0001), and RAS mutations in colorectal cancer (p < 0.01). Useful diagnostic properties which are commonly attributed to CK5/6 antibodies such as basal cell staining in the prostate, distinction of adenocarcinoma of the lung from squamous cell carcinoma and epithelioid mesothelioma, and identification of basal-type features in urothelial cancer are solely driven by CK5. At least for the purpose of distinguishing thoracic tumors, monospecific CK5 antibodies may be better suited than bispecific CK5/6 antibodies.

Molecular Pathology of Urothelial Carcinoma

Urothelial carcinoma is characterized by the presence of a wide spectrum of histopathologic features and molecular alterations that contribute to its morphologic and genomic heterogeneity. It typically harbors high rates of somatic mutations with considerable genomic and transcriptional complexity and heterogeneity that is reflective of its varied histomorphologic and clinical features. This review provides an update on the recent advances in the molecular characterization and novel molecular taxonomy of urothelial carcinoma and variant histologies.

Immune Checkpoint Inhibitors in Urothelial Bladder Cancer: State of the Art and Future Perspectives

Simple Summary

Urothelial bladder cancer (BC) is one of the most fatal cancers, with a dismal five-year survival rate of 5% in patients with metastatic disease. Clinically relevant benefits of immunotherapy in advanced or metastatic bladder cancer have led to Food and Drug Administration (FDA) approval of immune checkpoint inhibitors (ICIs) as second- or first-line therapy in patients unresponsive to or ineligible for standard treatment. The advantage of ICIs is being investigated in various stages of BC, either as monotherapy or in combination with other drugs. In this review we discuss the role of ICIs in BC, highlighting their current clinical application and outlining future therapeutic perspectives.

Abstract

Bladder cancer (BC) is the most common malignancy of the genitourinary tract, with high morbidity and mortality rates. Until recently, the treatment of locally advanced or metastatic urothelial BC was based on the use of chemotherapy alone. Since 2016, five immune checkpoint inhibitors (ICIs) have been approved by the Food and Drug Administration (FDA) in different settings, i.e., first-line, maintenance and second-line treatment, while several trials are still ongoing in the perioperative context. Lately, pembrolizumab, a programmed death-1 (PD-1) inhibitor, has been approved for Bacillus Calmette–Guérin (BCG)-unresponsive high-risk non-muscle invasive bladder cancer (NMIBC), using immunotherapy at an early stage of the disease. This review investigates the current state and future perspectives of immunotherapy in BC, focusing on the rationale and results of combining immunotherapy with other therapeutic strategies.

The Genitourinary Pathology Society Update on Classification of Variant Histologies, T1 Substaging, Molecular Taxonomy, and Immunotherapy and PD-L1 Testing Implications of Urothelial Cancers

The Genitourinary Pathology Society (GUPS) undertook a critical review of the recent advances in bladder cancer focusing on important topics of high interest for the practicing surgical pathologist and urologist. This review represents the second of 2 manuscripts ensuing from this effort. Herein, we address the effective reporting of bladder cancer, focusing particularly on newly published data since the last 2016 World Health Organization (WHO) classification. In addition, this review focuses on the importance of reporting bladder cancer with divergent differentiation and variant (subtypes of urothelial carcinoma) histologies and the potential impact on patient care. We provide new recommendations for reporting pT1 staging in diagnostic pathology. Furthermore, we explore molecular evolution and classification, emphasizing aspects that impact the understanding of important concepts relevant to reporting and management of patients.

Cytokeratin 5 and cytokeratin 20 inversely correlate with tumour grading in Ta non-muscle-invasive bladder cancer

Cytokeratin 5 is a marker of basal molecular subtypes of muscle‐invasive bladder cancer (MIBC), which correlates with worse overall survival compared to luminal subtypes. Our observations have not confirmed CK5 as a marker of high‐grade (HG) disease in Ta non‐muscle‐invasive bladder cancer (NMIBC). Therefore, to understand the basal‐luminal immunohistochemistry profile in Ta NMIBC, we performed immunohistochemistry for CK5, P40, P63 (basal), GATA3 and CK20 (luminal) and studied the correlation with HG and clinical outcome in 109 patients with Ta NMIBC. HG and low‐grade (LG) diseases were scored in each patient. Four different CK5 patterns were evaluated: absent (median 41.3%), normal (72.5%), rising (84.4%) and full thickness (23.9%). The median percentage of GATA3 was 100%. HG disease and CK5 expression and rising CK5 pattern had a significant inverse correlation, whereas HG disease and CK20 expression had a significant positive correlation. We also found a significant inverse correlation between CK5 expression and CK20 expression. Quantitative PCR confirmed that the presence of CK5 correlated with up‐regulation of CK5 RNA. None of the markers could differentiate patients with regard to clinical outcome. Our results suggest a role for CK5 and CK20 in differentiating between LG and HG disease in Ta NMIBC.

Nested Variant of Urothelial Carcinoma Is a Luminal Bladder Tumor With Distinct Coexpression of the Basal Marker Cytokeratin 5/6

OBJECTIVES

The nested variant of urothelial carcinoma (NVUC) is a rare bladder tumor that may possess a luminal molecular phenotype. We sought to determine whether a small immunohistochemical (IHC) panel using common surrogates for molecular phenotypes would reliably classify a cohort of pure NVUC cases.

METHODS

IHC staining with a panel composed of markers for basal subtypes (CK5/6, CK14) and luminal subtypes (FOXA1, GATA3) was performed on pure small NVUC cases (n = 23) and 5 large NVUC cases (n = 5). Scoring of IHC stains was performed semiquantitatively. Individual cases were analyzed using previously reported IHC-based surrogates for molecular subtype.

RESULTS

The phenotype of NVUC was classified as luminal from 60.1% (FOXA1+/CK5/6-) to 100% (GATA3+/CK14-) of cases using composite phenotypes. No cases possessed a basal or squamous cell carcinoma-like phenotype. The majority of small NVUC cases (69.5%) showed subset CK5/6 expression distinctly localized to the basal layers of tumor cell nests. Intratumoral heterogeneity was also noted in CK5/6 (21.7% of small NVUC cases) but no other markers.

CONCLUSIONS

NVUC appears to express markers of both basal and luminal bladder tumors. Definitive gene expression profiling may be valuable to further characterize this unique histologic variant.

Identification of a prognostic signature based on immune-related genes in bladder cancer

Bladder cancer (BLCA) has a high incidence and recurrence rate, and the effect of immunotherapy varies from person to person. Immune-related genes (IRGs) have been shown to be associated with immunotherapy and prognosis in many other cancers, but their role in immunogenic BLCA is less well defined. In this study, we constructed an eight-IRG risk model, which demonstrated strong prognostic and immunotherapeutic predictive power. The signature was significantly related to tumor clinicopathological characteristics, tumor class, immune cell infiltration and mutation status. Additionally, a nomogram containing the risk score and other potential risk factors could effectively predict the long-term overall survival probability of BLCA patients. The enriched mechanisms identified by gene set enrichment analysis suggested that the reason why this signature can accurately distinguish high- and low-risk populations may be closely related to the different degrees of innate immune response and T cell activation in different patients.

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.

Comprehensive Gene Expression Analyses of Immunohistochemically Defined Subgroups of Muscle-Invasive Urinary Bladder Urothelial Carcinoma

A number of urinary bladder urothelial carcinoma (UB UC) mRNA-based classification systems have been reported. It also has been observed that treatment response and prognosis are different for each molecular subtype. In this study, cytokeratin (CK)5/6 and CK20 immunohistochemistry (IHC) were performed, and IHC-based subgroup classification was applied. UB UC was classified into CK5/6 single-positive (SP), CK20 SP, double-positive (DP) and double-negative (DN) subgroups, and transcriptional analysis was performed. The results of gene ontology (GO) terms and functional analysis using differentially expressed genes indicate that, CK5/6 SP and DP subgroups were enriched in cell migration, immune activation, interleukin 6-Janus kinase-signal transducer and activator of transcription 3 (IL6-JAK-STAT3) signaling pathway and tumor necrosis factor-α signaling via the nuclear factor-κB (NF-κB) signaling pathway signature gene. In addition, compared with the other subgroups, the DN subgroup showed inhibited cell movement, cell migration, and cell activation. Furthermore, in survival analysis, the CK5/6 SP subgroup was significantly associated with poor progression-free survival (p = 0.008). The results of our study indicate that the CK5/6 positive subgroup exhibited high gene expression signature related to aggressive behavior and exhibited worse clinical outcome.

The Differential Diagnosis of Medullary-Based Renal Masses

CONTEXT.—

Renal malignancies can be divided into cortical- and medullary-based tumors, the latter of which classically infiltrate the renal parenchyma by extending between nonneoplastic structures. Although high-grade cortical tumors can rarely exhibit the same growth pattern, the infiltrative morphology should elicit a differential diagnosis to be considered in each case. However, these diagnoses can be challenging to distinguish, especially on small renal biopsy samples.

OBJECTIVE.—

To provide an overview of the clinical, gross, and microscopic findings; genetic and molecular alterations; and immunohistochemical evaluation of medullary-based renal tumors and other tumor types with overlapping morphologies and growth patterns.

DATA SOURCES.—

Literature review and personal observations were used to compile the information in this review.

CONCLUSIONS.—

Collecting duct carcinoma is a prototypical medullary-based tumor, and although diagnostic criteria exist, it remains a diagnosis of exclusion, especially with ancillary techniques aiding the recognition of established as well as more recently described neoplasms. Other medullary-based malignancies included in the differential diagnosis include renal medullary carcinoma/renal cell carcinoma unclassified with medullary phenotype, fumarate hydratase-deficient renal cell carcinoma, and upper tract urothelial carcinoma. Moreover, other rare entities should be excluded, including metastatic carcinoma, lymphoma, and melanoma. In addition to potential prognostic differences, accurate diagnoses can have important surgical and clinical management implications.

Combined use of immunohistochemical markers of basal and luminal subtypes in urothelial carcinoma of the bladder: Association with clinicopathological features and outcomes

OBJECTIVES

Whole genome expression profiles allow the stratification of bladder urothelial carcinoma into basal and luminal subtypes which differ in histological patterns and clinical behavior. Morpho-molecular studies have resulted in the discovery of immunohistochemical markers that might enable discrimination between these two major phenotypes of urothelial carcinoma.

METHODS

We used two combinations of immunohistochemical markers, i.e., cytokeratin (CK) 5 with CK20 and CK5 with GATA3, to distinguish subtypes, and investigated their association with clinicopathological features, presence of histological variants, and outcomes. Upon searching for tumor heterogeneity, we compared the findings of primary tumors with their matched lymph node metastases. We collected data from 183 patients who underwent cystectomy for high-grade muscle-invasive urothelial carcinoma, and representative areas from the tumors and from 76 lymph node metastasis were organized in tissue microarrays.

RESULTS

Basal immunohistochemical subtype (CK5 positive and CK20 negative, or CK5 positive and GATA3 negative) was associated with the squamous variant. The luminal immunohistochemical subtype (CK5 negative and CK20 positive, or CK5 negative and GATA3 positive) was associated with micropapillary and plasmacytoid variants. Remarkably, only moderate agreement was found between the immunohistochemical subtypes identified in bladder tumors and their lymph node metastasis. No significant difference in survival was observed when using either combination of the markers.

CONCLUSION

This study demonstrates that these three routinely used immunohistochemical markers could be used to stratify urothelial carcinomas of the bladder into basal and luminal subtypes, which are associated with several differences in clinicopathological features.

PD-L1 Expression in Muscle-Invasive Urinary Bladder Urothelial Carcinoma According to Basal/Squamous-Like Phenotype

Urothelial carcinoma (UC) is the most common histologic type of urinary bladder cancer, and muscle-invasive UC shows aggressive behaviors. Programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) blockades have been approved as standard treatments for patients with advanced stage UC. A total of 166 muscle-invasive urinary bladder cancer (MIBC) patients, who underwent transurethral resection of the bladder or cystectomy from 2004 to 2010 were included. We evaluated PD-L1 expression by the SP142 and SP263 assays and classified the cases “positive” or “negative” according to the manufacturer’s recommendations. We performed immunohistochemistry (IHC) for cytokeratin (CK) 5/6, CK14, GATA3, FOXA1, and CK20 and classified samples as Basal-Squamous-like (BASQ) or non-BASQ subtype. The overall concordance rate for PD-L1 expression is 91.6% (152/166) (kappa = 0.732). The SP142 assay showed 15.1% positivity; the SP263 assay showed 23.5%. The high positivity in the SP142 and SP263 assay was significantly correlated with positive CK5/6, CK14 expression, negative GATA3, FOXA1, and CK20 expression. Classification according to IHC expression resulted in 12.0% (20/166) of samples being classified as BASQ subtype and 88.0% (146/166) of samples being classified as non-BASQ subtype. High positivity in the SP142 and SP263 assay was significantly correlated with the BASQ subtype (p < 0.001, both). Our study is the first to analyze the association of immunohistochemically defined BASQ and non-BASQ subtypes with two PD-L1 assays in MIBC. In conclusion, we revealed that a high PD-L1 positive rate in all PD-L1 assays was significantly associated with the BASQ-subtype, and these results suggest that the BASQ classification may be important to apply the PD-1/PD-L1 blockades in MIBC.

Update on bladder cancer molecular subtypes

In 2014, there was a burst of studies on the molecular subtypes of bladder cancer in the published literature that was made possible by the advances in high-throughput technologies. Based on gene expression profiling, the major molecular classification subdivisions were basal and luminal subtypes, which resembled to those observed in breast cancers. These basal and luminal subtypes were further subdivided by TCGA into squamous, infiltrated, luminal-papillary, luminal/genomically unstable (GU), and neuronal/small cell carcinoma (SCC) subtypes. Recently, an international subtypes consensus project further expanded on the TCGA subtypes by defining a consensus molecular classification (CMC). A multidisciplinary team of experts generated CMC to overcome the difficulties of clinical applications due to several published bladder cancer molecular classifications with various nomenclatures and molecular features. It included six molecular subtypes with the addition of one more luminal subtype (luminal nonspecified) compared to the TCGA subtype classification. The initial research efforts have focused on the characterization of each subtype at the molecular and histopathologic levels, but more recent studies have examined their significance in terms of clinical utility, i.e., biomarkers that inform prognostication and/or to predict therapeutic responses to be tested in future clinical trials. This review provides an overview of recent investigations into the relationship between molecular subtypes and the clinical management of patients with bladder cancer.

[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.

A four-antibody immunohistochemical panel can distinguish clinico-pathological clusters of urothelial carcinoma and reveals high concordance between primary tumor and lymph node metastases

Urothelial carcinoma of the bladder (UC) has a poor prognosis, partly because of chemotherapy resistance. Molecular classifications have shown their interest and can help to offer personalized treatment. In this study, we evaluated the feasibility of an immunohistochemical study to divide advanced UC into clinico-pathological-molecular subgroups and evaluate phenotypic correspondence between primary UC and matched lymph node metastases (LMN). An eight-antibody immunohistochemical panel was performed on UC and matched LMN from patients treated with radical cystectomy. One hundred eighty-seven UCs (100 pN0 tumor and 87 pN+ tumor) were tested. Multiple correspondence analysis showed that UC expressing GATA3 also expressed FOXA1 (p = 0.010) and did not stain for CK5/6 (p = 0.031) nor CK14 (p = 0.003). UC expressing CK14 coexpressed CK5/6 (p < 0.0001), had high Ki67 (p = 0.010) and no GATA3 (p = 0.003) nor FOXA1 (p = 0.011) expression. Loss of expression of STAG2 was associated with high Ki67 (p = 0.001). Sixty-seven percent of [CK5/6 CK14]+ [GATA3 FOAXA1]- patients had high Ki67 expression vs 37% of [GATA3 FOXA1]+ [CK5/6 CK14]- patients (p = 0.024). The majority of [CK5/6 CK14]+ [GATA3 FOAXA1]- patients (92%) had advanced disease (pT3-pT4) whilst 86% of pT1-T2 cases were [GATA3 FOXA1]+ [CK5/6 CK14]- (p = 0.041). Differential antigen expression between 63 pN+ primary tumors and their corresponding LNM showed the following concordance percentages: p53 (76%), p63 (75%), CK5/6 (65%), CK14 (89%), GATA3 (75%), FOXA1 (68%), STAG2 (65%), and Ki-67 (71%). These results support the interest of immunohistochemistry for subtype profiling in metastatic UC, using CK5/6, CK14, GATA3, and FOXA1, highlighting also few phenotypical modifications when tumor spreads to lymph nodes.

Focus on Biochemical and Clinical Predictors of Response to Immune Checkpoint Inhibitors in Metastatic Urothelial Carcinoma: Where Do We Stand?

Urothelial bladder cancer is one of the most lethal cancers worldwide with barely 5% five-year survival in patients with metastatic disease. Intravesical immunotherapy with Bacillus Calmette-Guérin and platinum-based chemotherapy are currently the standard of care for non-muscle invasive and advanced or metastatic urothelial cancer (mUC), respectively. Recently, a subset of patients with locally advanced or mUC has shown to be responsive to immune checkpoint inhibitors (ICIs), e.g., the anti-cytotoxic T-lymphocyte-associated protein 4 and programmed cell death -1/programmed death-ligand1 (PD-1/PD-L1) antibodies. Due to the relevant clinical benefit of immunotherapy for mUC, in 2016, the United States Food and Drug Administration (FDA) approved five immunotherapeutic agents as second-line or first-line treatments for patients with advanced bladder cancer who did not profit from or were ineligible for standard therapy. In this review, we discuss the role of immunotherapy in bladder cancer and recent clinical applications of PD-1/PD-L1 blockade in mUC. Furthermore, we evaluate a variable response rate to ICIs treatment and outline potential biomarkers predictive of immunotherapy response.

Non-Muscle-Invasive Bladder Carcinoma with Respect to Basal Versus Luminal Keratin Expression

Non-muscle-invasive bladder cancer (NMIBC) consists of transcriptional subtypes that are distinguishable from those of muscle-invasive cancer. We aimed to identify genetic signatures of NMIBC related to basal (K5/6) and luminal (K20) keratin expression. Based on immunohistochemical staining, papillary high-grade NMIBC was classified into K5/6-only (K5/6High-K20Low), K20-only (K5/6Low-K20High), double-high (K5/6High-K20High), and double-low (K5/6Low-K20Low) groups (n = 4 per group). Differentially expressed genes identified between each group using RNA sequencing were subjected to functional enrichment analyses. A public dataset was used for validation. Machine learning algorithms were implemented to predict our samples against UROMOL subtypes. Transcriptional investigation demonstrated that the K20-only group was enriched in the cell cycle, proliferation, and progression gene sets, and this result was also observed in the public dataset. The K5/6-only group was closely regulated by basal-type gene sets and showed activated invasive or adhesive functions. The double-high group was enriched in cell cycle arrest, macromolecule biosynthesis, and FGFR3 signaling. The double-low group moderately expressed genes related to cell cycle and macromolecule biosynthesis. All K20-only group tumors were classified as UROMOL "class 2" by the machine learning algorithms. K5/6 and K20 expression levels indicate the transcriptional subtypes of NMIBC. The K5/6Low-K20High expression is a marker of high-risk NMIBC.

The value and limitations of urothelial bladder carcinoma molecular classifications to predict oncological outcomes and cancer treatment response: A systematic review and meta-analysis

AIM

To evaluate the predictive value of molecular subtypes on oncological outcomes and response to cancer treatment in patients with urothelial bladder carcinoma (UBC).

MATERIALS AND METHODS

A literature search using PubMed, Scopus, and Cochrane Library was conducted on April 2020 to identify relevant studies according to the preferred reporting items for systematic review and meta-analysis guidelines. The pooled overall survival (OS), cancer-specific survival (CSS), and progression-free survival were calculated using a fixed or random effects model.

RESULTS

We identified 66 studies (including 21,447 molecular subtype records) evaluating the impact of molecular classification on oncologic outcomes in patients with UBC. We found significant association of different molecular subtypes with OS, CSS, progression-free survival, recurrence-free survival, and response to treatment. Totally, 11 studies were included in the meta-analysis. Basal group and NE-like subtypes were associated with worse OS (pooled HR: 1.78, 95%CI: 1.49-2.12, and pooled HR: 2.67, 95%CI: 1.08-6.60, respectively) in patients with muscle invasive bladder cancer. Luminal group was also associated with worse CSS (pooled HR of 3.67, 95%CI: 2.19-6.14).

CONCLUSIONS

Based on these data, UBC molecular classifications are significant predictors of oncological outcomes and identify patients who are most likely to benefit from intensified or different therapies. The optimal consensus on molecular classification remains to be verified in well-designed prospective studies to allow precise prognostic and predictive value assessment.

lncRNA SNHG1 Promotes Basal Bladder Cancer Invasion via Interaction with PP2A Catalytic Subunit and Induction of Autophagy

Although basal muscle-invasive bladder cancers (MIBCs) are predominant, are more aggressive, and have bad prognoses, molecular mechanisms underlying how basal MIBC formation/progression have been barely explored. In the present study, SNHG1, a long non-coding RNA, was shown to be expressed at higher levels in basal MIBC cells than in other types of bladder BC cells, and its presence could promote basal MIBC cell invasion. The results revealed that SNHG1 specifically induced MMP2 expression via increasing its transcription and mRNA stability. In one mechanism, SNHG1 directly bound with PP2A catalytic subunit (PP2A-c) to inhibit interactions of PP2A-c with c-Jun and then promoted c-Jun phosphorylation that, in turn, mediated MMP2 transcription. In another mechanism, SNHG1 markedly induced autophagy in the cells via induction of increases in the abundance of autophagy-related proteins. The latter initiated autophagy and further abolished miR-34a stability, which reduced overall miR-34a binding directly to the 3' UTR of MMP2 mRNA, thereby promoting MMP2 mRNA stabilization. These results provided novel insight into understanding the specific functions of SNHG1 in basal MIBC. Such findings may ultimately prove highly significant for the design/synthesis of new SNHG1-based compounds for the treatment of basal MIBC patients.

Rapidly Progressive Invasive Urothelial Carcinoma With Flat and Infiltrative Growth Pattern in the Graft Kidney After Living-Related Kidney Transplantation: A Case Report

BACKGROUND

Because immunosuppression is necessary for kidney transplant recipients, malignant tumorigenesis of recipient organs is a concern; however, few studies have discussed the malignant alteration of transplanted grafts that have been functional for a long time. In addition, a urothelial carcinoma (UC) in transplanted kidney graft is a rare disease.

CASE REPORT

A 62-year-old man had end-stage renal failure 31 years ago and received a kidney transplant from his father. Acute renal failure due to obstruction of the transplanted ureter was diagnosed. Ultrasound, ureterogram, and non-enhanced computed tomography scans revealed no obvious evidence of any neoplastic lesion. We treated the obstruction and hydronephrosis with transplant ureter stenting. However, the regional lymph nodes enlarged, and it became necessary to change the ureteral stent frequently because of stent stenosis; therefore, he underwent lower transplant ureteral resection and reconstruction. Histopathology confirmed a UC with a flat and infiltrative growth pattern. The patient then underwent graftectomy including right external iliac vein resection and reconstruction; however, because of numerous metastatic nodules, radical surgery could not be performed. The patient subsequently died because of septic shock after the second surgery.

CONCLUSION

We report a case of an invasive UC with a flat and infiltrative growth pattern derived from a transplant kidney graft that occurred 31 years after a living-donor transplant that could not be treated immediately and was difficult to diagnose.

Assessment of Luminal and Basal Phenotypes in Bladder Cancer

Genomic profiling studies have demonstrated that bladder cancer can be divided into two molecular subtypes referred to as luminal and basal with distinct clinical behaviors and sensitivities to frontline chemotherapy. We analyzed the mRNA expressions of signature luminal and basal genes in bladder cancer tumor samples from publicly available and MD Anderson Cancer Center cohorts. We developed a quantitative classifier referred to as basal to luminal transition (BLT) score which identified the molecular subtypes of bladder cancer with 80–94% sensitivity and 83–93% specificity. In order to facilitate molecular subtyping of bladder cancer in primary care centers, we analyzed the protein expressions of signature luminal (GATA3) and basal (KRT5/6) markers by immunohistochemistry, which identified molecular subtypes in over 80% of the cases. In conclusion, we provide a tool for assessment of molecular subtypes of bladder cancer in routine clinical practice.

CK14 Expression Identifies a Basal/Squamous-Like Type of Papillary Non-Muscle-Invasive Upper Tract Urothelial Carcinoma

Object: CK14 expression is an important marker of basal/squamous-like (BASQ)-type muscle-invasive bladder carcinoma, and this molecularly defined subtype has a poor prognosis and a distinct response to chemotherapy. However, CK14 expression and its clinicopathological and molecular significance in papillary non-muscle-invasive upper tract urothelial carcinoma (NMIUTUC) remain unknown. Herein, we investigated the prognostic implications of immunohistochemical (IHC) staining for CK14 and the transcriptional characteristics associated with CK14 expression in papillary NMIUTUC. Materials and Methods: IHC staining for CK14 was conducted in 204 papillary NMIUTUC specimens. Positive CK14 IHC staining was defined as a positive signal in >0% of tumor cells. RNA sequencing data were analyzed from 8 papillary high-grade NMIUTUC specimens consisting of 4 CK14-positive and 4 CK14-negative tumors. Results: CK14 positivity was associated with a high TNM stage (p < 0.001) and a high World Health Organization grade (p = 0.003). Survival analysis showed that CK14 positivity was significantly associated with poor progression-free survival (p = 0.015; hazard ratio [HR] = 2.990; 95% confidence interval [CI] = 1.180-7.580) and was marginally associated with poor cancer-specific survival (p = 0.052; HR = 3.77; 95% CI = 0.900-15.780). Gene set enrichment analysis demonstrated that the CK14-positive tumors were associated with a basal subtype of breast cancer, squamous cell carcinoma development, p40, tumor necrosis factor α-nuclear factor-κB, and p53 pathways, and embryonic stem cells; these characteristics are reminiscent of the BASQ subtype. In addition, with a p < 0.05 and |fold change| ≥2 as the cutoffs, we identified 178 differentially expressed genes when comparing CK14-positive and CK14-negative tumors. Functional analysis of these genes revealed several networks and gene ontology terms related to the positive regulation of cellular proliferation in CK14-positive tumors. Consistent with these results, we demonstrated that the mean Ki-67 proliferative index was higher in CK14-positive tumors than it was in CK14-negative tumors (2.3 vs. 0.8%, respectively, p = 0.002). Conclusion: CK14-positive papillary NMIUTUC is an aggressive subtype with BASQ-like molecular characteristics and dynamic proliferative activity. We propose that CK14 IHC staining can be a useful biomarker of BASQ-type papillary NMIUTUC that can be applied in daily practice with the aim of precision oncology.

Management of Muscle-invasive Bladder Cancer in the 2020s: Challenges and Perspectives

Despite an increased use of neoadjuvant and adjuvant chemotherapy, the long-term survival rates after radical cystectomy or trimodal therapy (TMT) for muscle-invasive bladder cancer (MIBC) remain basically unchanged for decades. Detection and effective treatment of micrometastatic disease are still a clinical dilemma. Assessment of circulating tumor DNA in combination with improved imaging modalities may improve the prediction of micrometastatic disease. Different genetic subtypes of MIBC show varying degrees of chemosensitivity. Further progress needs to be made in order to develop a common molecular classifier that can be used easily for daily clinical decision making. With the advent on immuno-oncology, bladder-sparing protocols are on the rise as an alternative to surgery. The extent of transurethral bladder tumor resection has a marked impact on the response rates to TMT and neoadjuvant chemotherapy. This review focuses on strategies regarding how to integrate surgery, radiotherapy, and molecular-based systemic treatment for improved oncological outcomes of patients with MIBC. PATIENT SUMMARY: Effective treatment of micrometastatic disease is the key to improved oncological outcomes in muscle-invasive bladder cancer and requires a multidisciplinary approach.

Updates on the Genomics of Bladder Cancer and Novel Molecular Taxonomy

Urothelial carcinoma (UC) is the most common malignant neoplasm of the bladder that encompasses a wide spectrum of histopathologic features and various molecular alterations and subtypes, responsible for its significant morphologic and genomic heterogeneity. Morphologically, in addition to classic UC (not otherwise specified), many well documented variant histologies are a common finding in invasive UC, and include squamous, glandular, micropapillary, sarcomatoid, small cell/neuroendocrine, clear cell, lymphoepithelioma-like, and plasmacytoid types, among others. This review provides an update on the recent advances in the molecular characterization and novel molecular taxonomy of UC and variant histologies.