Clinical and Genomic Considerations for Variant Histology in Bladder Cancer

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 characterization of plasmacytoid urothelial carcinoma and the impact on treatment implications

Bladder cancer researchers and clinicians have increasingly viewed tumor biology through the lens of genomic and molecular alterations, drastically improving our knowledge of the underlying disease biology. This understanding has led to significant advances in treatment options that allow implementation of a personalized approach to cancer treatment. Large-scale genomic studies initially focused on the most common forms of bladder cancer. However, as genomic and molecular technologies become more widespread and are applied to less common variant histologies, we are gaining additional insight into the unique molecular and genomic characteristics driving the biology of variant histologies of bladder cancer. In this review, we summarize the current state of knowledge of molecular alterations underlying the distinct tumor biology of plasmacytoid urothelial carcinoma and how these alterations may impact treatment options.

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.

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

Simple Summary

Although it is one disease, cancer of the urinary bladder occurs in several molecular subtypes that can be identified by laboratory tests. Tumors of advanced stages are treated with surgical removal of the urinary bladder with or without addition of chemotherapy. About 50% of patients are cured by surgery and this proportion is increased slightly by the addition of chemotherapy. Still, many patients do not benefit from chemotherapy, which also comes with significant toxicity. Recent advances in the field suggest that molecular subtypes can help identify patient categories that do or do not benefit from adding chemotherapy to surgery. In this article, we review the literature and conclude that molecular subtypes are likely to have such a role in the future but that there are differences between studies that make them challenging to compare. The current evidence is insufficient to guide clinical practice.

Abstract

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.

Expression of GATA3 and Cytokeratin 14 in Urinary Bladder Carcinoma (Histopathological and Immunohistochemical Study)

BACKGROUND: Urothelial carcinoma (UC) with squamous differentiation (SD) is the most common histologic variant of bladder carcinoma and its presence is associated with poor prognosis which may need early radical cystectomy to avoid progression and recurrence. It is difficult to detect few foci of SD, especially nonkeratinizing or early switch from urothelial to squamous epithelium on only morphological basis. Combination of GATA3 and Cytokeratin 14 (CK14) could be helpful in differentiating pure UC, UC with SD and pure squamous cell carcinoma (SCC). AIM: Assessment of GATA3 and CK14 expression in urinary bladder carcinoma and correlation with clinical and histopathological variables, for both diagnostic and prognostic purposes. MATERIALS AND METHODS: Sixty cases of archived paraffin blocks of urinary bladder carcinoma were tested for GATA3 and CK14 expression by immunohistochemistry using a rabbit monoclonal antibody against human CK 14 and mouse monoclonal antibody against GATA3, respectively. RESULTS: There is a significant correlation between GATA3 immunohistochemical expression and histological tumor subtypes of bladder carcinoma (p < 0.001), i.e. the GATA3 is a useful marker for urothelial origin especially in papillary UC. There is a significant correlation between GATA3 immunohistochemical expression and UC grade (p < 0.001). CK14 showed positive cytoplasmic staining in 9/14 (64.3%) cases of UC with SD and (13/13) (100%) cases of pure SCC and negative in 33/33(100%) cases of UC other than UC with SD. CK14 had sensitivity (64.3%) and specificity (100%) for areas of SD. CONCLUSION: GATA3 is a specific immunohistochemical marker for urothelial origin. CK14 is a highly specific and sensitive immunohistochemical marker of squamous cell carcinoma.

Effect of bladder cancer variant histology on survival outcome in patients treated with radical cystectomy: A single-centre experience

Context

Bladder cancer (BC) is the sixth most common malignant neoplasm in men. Recently, great effort has been devoted to the study of BC variant histology (VH). Yet, the results from these studies have shown conflicting data and remain unclear whether their presence alters recurrence and survival rates after radical cystectomy (RC).

Aims

We undertook this study aiming to test the effect on VH on recurrence-free survival (RFS) and overall survival (OS) in single-center RC patients.

Settings and Design

We have retrospectively analyzed medical records and pathology reports from 331 patients who underwent RC with or without pelvic lymphadenectomy at University Urology Clinic-Skopje, North Macedonia, in the period between 2010 and 2018.

Subjects and Methods

Microscopic analysis of the specimens involved the evaluation of histological tumor type, tumor grade, pathological tumor node metastasis stage, presence of lymphovascular invasion, and resection margin status.

Statistical Analysis Used

Univariable and multivariable Cox regression models were applied to test the effect of VH on RFS and OS.

Results

We found 185 patients who matched our inclusion criteria. At multivariable analyses, lymphovascular invasion and positive resection margins were associated with shorter RFS. Similarly, patients diagnosed with lymphovascular invasion, positive resection margins, and a pelvic lymph node metastasis had poorer OS. VH was not found to be an independent predictor of both RFS and OS (P > 0.05).

Conclusions

The present study did not reveal prognostic effect of VH on RFS and OS. In our series, histomorphologic parameters including lymphovascular invasion, resection margins, and pelvic lymph node metastasis were the most relevant predictors on survival outcome after RC.

Prognostic impact of molecular muscle-invasive bladder cancer subtyping approaches and correlations with variant histology in a population-based mono-institutional cystectomy cohort

Purpose

Recently discovered molecular classifications for urothelial bladder cancer appeared to be promising prognostic and predictive biomarkers. The present study was conducted to evaluate the prognostic impact of molecular subtypes assessed by two different methodologies (gene and protein expression), to compare these two approaches and to correlate molecular with histological subtypes in a consecutively collected, mono-institutional muscle-invasive bladder cancer (MIBC) cohort.

Methods

193 MIBC were pathologically re-evaluated and molecular subtypes were assessed on mRNA (NanoString technology, modified 21-gene-containing MDACC approach) and protein levels (immuno-histochemical [IHC] analysis of CK5, CK14, CD44, CK20, GATA3 and FOXA1). Descriptive statistical methods and uni-/multi-variable survival models were employed to analyze derived data.

Results

Neither gene expression nor protein-based subtyping showed significant associations with disease-specific (DSS) or recurrence-free survival (RFS). Agreement between mRNA (reference) and protein-based subtyping amounted 68.6% for basal, 76.1% for luminal and 50.0% for double-negative tumors. Histological subtypes associated with RFS in uni-variable (P = 0.03), but not in multivariable survival analyses. Tumors with variant histology predominantly showed luminal subtypes (gene expression subtyping: 36/55 cases, 65.5%; protein subtyping: 44/55 cases, 80.0%). Squamous differentiation significantly associated with basal subtypes (gene expression subtyping: 44/45 squamous cases, 97.8%; protein subtyping: 36/45 cases, 80.0%).

Conclusion

In our consecutive cystectomy cohort, neither gene, protein expression-based subtyping, nor histological subtypes associated with DSS or RFS in multi-variably adjusted survival analyses. Application of a limited IHC subtyping marker panel showed high concordance of 83.9% with gene expression-based subtyping, thus underlining the utility for subtyping in pathological routine diagnostics. In addition, histological MIBC subtypes are strong indicators for intrinsic subtypes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00345-021-03788-1.

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.

Non-Muscle Invasive Bladder Cancer with Variant Histology: Biological Features and Clinical Implications

BACKGROUND

The most common bladder cancer (BC) histotype is pure urothelial carcinoma (UC), which may undergo divergent differentiation in some cases. Variant histology (VH) presents along variable morphologies, either single or combined between them or with pure UC. From a clinical standpoint, the vast majority of BC is diagnosed at non-invasive or minimally invasive stages, namely as non-muscle invasive BC (NMIBC). There is a wide range of therapeutic options for patients with NMIBC, according to their clinical and pathological features. However, current risk stratification models do not show optimal effectiveness. Evidence from the literature suggests that VH has peculiar biological features, and may be associated with poorer survival outcomes compared to pure UC.

SUMMARY

In order to describe the biological features and prognostic/predictive role of VH in NMIBC, and to discuss current treatment options, we performed a systematic literature search through multiple databases (PubMed/Medline, Google Scholar) for relevant articles according to the following terms, single and/or in combination: "non-muscle invasive bladder cancer," "variant histology," "micropapillary variant," "glandular differentiation," "squamous differentiation," "nested variant," "plasmacytoid variant," and "sarcomatoid variant." We extracted 99 studies including original articles, reviews, and systematic reviews, and subsequently analyzed data from 16 studies reporting on the outcome of NMIBC with VH. We found that the relative rarity of these forms as well as the heterogeneity in study populations and therapeutic protocols results in conflicting findings overall. Key Messages: The presence of VH should be taken into account when counseling a patient with NMIBC, since it may upgrade the disease to high-risk tumor and thus warrant a more aggressive treatment.

Pathological and Survival Outcomes Associated with Variant Histology Bladder Cancers Managed by Cystectomy with or without Neoadjuvant Chemotherapy

PURPOSE

Although neoadjuvant chemotherapy is associated with a survival advantage in pure urothelial, muscle invasive bladder cancer, the role of neoadjuvant chemotherapy is less clear in variant histology or urothelial carcinoma with divergent differentiation. We compared chemotherapy response and survival outcomes of patients with nonpure urothelial carcinoma histology who were managed with neoadjuvant chemotherapy followed by cystectomy vs cystectomy alone.

MATERIALS AND METHODS

We analyzed 768 patients with clinical muscle invasive bladder cancer (cT2-4N0M0) who were treated with cystectomy at a tertiary care center from 2007 to 2017. Patients were stratified by histology and treatment strategy. Adjusted logistic and Cox regression models were used to evaluate pathological downstaging, cancer specific survival and overall survival.

RESULTS

The cohort consisted of 410 patients (53%) with pure urothelial carcinoma, 185 (24%) with urothelial carcinoma with divergent differentiation and 173 (23%) with variant histology. Overall, 314 patients (41%) received neoadjuvant chemotherapy prior to cystectomy. There were similar rates of complete (18% to 30%) and partial (37% to 46%) pathological downstaging with neoadjuvant chemotherapy across all histological subgroups (p=0.30 and p=0.40, respectively). However, while patients with pure urothelial carcinoma experienced an overall survival benefit (HR 0.71, 95% CI 0.51-0.98, p=0.0013) and those with variant histology experienced a cancer specific survival benefit (HR 0.55, 95% CI 0.30-0.99, p=0.0495) with neoadjuvant chemotherapy, patients with urothelial carcinoma with divergent differentiation did not experience overall or cancer specific survival benefits with the use of neoadjuvant chemotherapy prior to cystectomy.

CONCLUSIONS

Among patients with muscle invasive bladder cancer those with nonpure urothelial carcinoma histology with variant histology achieved nearly equivalent response rates and survival benefits with the use of neoadjuvant chemotherapy as those with pure urothelial carcinoma, while patients with urothelial carcinoma with divergent differentiation experienced significantly worse survival outcomes regardless of the use of neoadjuvant chemotherapy prior to cystectomy.

Role of Neoadjuvant Chemotherapy in Squamous Variant Histology in Urothelial Bladder Cancer: Does Presence and Percentage Matter?

BACKGROUND

The purpose of this study was to evaluate the effect of neoadjuvant chemotherapy (NACT) on squamous variant (SV) bladder cancer by investigating patients presenting with SV histology at the time of transurethral resection (TUR), stratified by their receipt of NACT.

MATERIALS AND METHODS

The records of 71 patients with muscle-invasive bladder cancer and SV in the TUR specimen who underwent cystectomy between 2008 and 2018 were reviewed. Our primary outcome was pathologic response at time of cystectomy. Secondary outcomes included recurrence-free survival and overall survival stratified by receipt of NACT. A subgroup analysis was then conducted on the patients with defined SV% on TUR stratified by % involvement (< 50% SV vs. ≥ 50% SV).

RESULTS

The median age of the NACT and no-NACT groups was 60.2 and 70 years, respectively (P = .003). The complete response rate at cystectomy was 60% versus 13.7% for the NACT and no-NACT groups, respectively (P < .001). The non-organ-confined disease rate at time of radical cystectomy was 35% for the NACT group and 68.6% for the no-NACT group (P = .01). The NACT group had fewer recurrences than the no-NACT group (10% vs 47.1%; P = .003). In the subgroup analysis, the lower rate of non-organ-confined disease persisted for the patients who underwent NACT at the lower SV percentage but failed to remain significant at greater percentage involvement. This was also true for overall survival.

CONCLUSIONS

The effect of NACT in variant histology bladder cancer is variable. In patients with SV, these results favor the recommendation in favor of NACT administration, particularly when the primary tumor has < 50% involvement by the variant histology.

Harmine suppresses bladder tumor growth by suppressing vascular endothelial growth factor receptor 2-mediated angiogenesis

Angiogenesis is a vital step during the process of oncogenesis of a lot of tumors, with no exception in bladder cancer. One of the useful strategies for the development of new drugs against cancer is targeting angiogenesis. In the present study, we found that a small-molecule natural product, which belonged to the β-carboline alkaloid, named harmine, could strongly inhibit tumor angiogenesis thus exhibiting its ideal treatment efficacy in bladder cancer. In vivo study verified that harmine had the effect of inhibition on human bladder tumor xenograft growth. The inhibitory effect of harmine to bladder cancer growth was coordinated by the effects shown on angiogenesis. To further explore the pharmacological activities of harmine, we tested harmine’s influence on blood vessel formation and found that harmine effectively blocked the microvessel sprouting in rat aortic ring assay when stimulated by vascular endothelial growth factor (VEGF). Furthermore, harmine inhibited human umbilical vein endothelial cell (HUVEC) proliferation as well as chemotactic motility, and when we treated HUVEC cell with harmine, the formation of capillary-like structures was also restrained. Moreover, harmine induced bladder cancer cell apoptosis through triggering the caspase-dependent apoptotic pathway and the downstream vascular endothelial growth factor receptor 2 (VEGFR2) kinase pathway was down-regulated, thus suppressing tumor development signals. Herein, our study demonstrated that natural product harmine might have potential in curing human bladder tumor because of its pharmacological function on tumor angiogenesis, trigged by VEGFR2 signaling pathways.