Outcome of patients with micropapillary urothelial carcinoma following radical cystectomy: ERBB2 (HER2) amplification identifies patients with poor outcome

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.

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.

Current Advances in the Management of Nonurothelial Subtypes of Bladder Cancer

Urothelial cancer (UC) is the most common histology seen in bladder tumors. The 2022 WHO classification of urinary tract tumors includes a list of less common subtypes (formerly known as variants) for invasive UC which are considered high-grade tumors. This review summarizes the most recent advances in the management of selected nonurothelial subtypes of bladder cancer: squamous cell carcinoma, small cell carcinoma, sarcomatoid urothelial carcinoma, micropapillary carcinoma, plasmacytoid carcinoma, adenocarcinoma, and urachal carcinoma. The role of neoadjuvant and adjuvant chemotherapy has not been well characterized for most of these histologies, and prospective data are extremely limited. Participation in clinical trials is recommended in advanced disease.

Frequency and Nature of Genomic Alterations in ERBB2-Altered Urothelial Bladder Cancer

BACKGROUND

Human epidermal growth factor-2 (HER2) overexpression is an oncogenic driver in many solid tumors, including urothelial bladder cancer (UBC). In addition, activating mutations in the ERBB2 gene have been shown to play an oncogenic role similar to ERBB2 amplification.

OBJECTIVE

To describe and compare the frequency and nature of genomic alterations (GA) of ERBB2-altered (mutations, amplification) and ERBB2 wild-type UBC.

PATIENTS AND METHODS

Using a hybrid capture-based comprehensive profiling assay, 9518 UBC cases were grouped by ERBB2 alteration and evaluated for all classes of genomic alterations (GA), tumor mutational burden (TMB), microsatellite instability (MSI), genome-wide loss of heterozygosity (gLOH), and genomic mutational signature. PD-L1 expression was measured by immunohistochemistry (Dako 22C3). Categorical statistical comparisons were performed using Fisher's exact tests.

RESULTS

A total of 602 (6.3%) UBC cases featured ERBB2 extracellular domain short variant (SV) GA (ECDmut+), 253 (2.7%) cases featured ERBB2 kinase domain SV GA (KDmut+), 866 (9.1%) cases had ERBB2 amplification (amp+), and 7797 (81.9%) cases were ERBB2 wild-type (wt). European genetic ancestry of ECDmut+ was higher than ERBB2wt. Numerous significant associations were observed when comparing GA by group. Notably among these, CDKN2A/MTAP loss were more frequent in ERBB2wt versus ECDmut+ and amp+. ERBB3 GA were more frequent in ECDmut+ and KDmut+ than ERBB2wt. TERT GA were more frequent in ECDmut+, KDmut+, and amp+ versus ERBB2wt. TOP2A amplification was significantly more common in ECDmut+ and amp+ versus ERBB2wt, and TP53 SV GA were significantly higher in ERBB2 amp+ versus ERBB2wt. Mean TMB levels were significantly higher in ECDmut+, KDmut+, and amp+ than in ERBB2wt. Apolipoprotein B mRNA-editing enzyme, catalytic polypeptides (APOBEC) signature was more frequent in ECDmut+, KDmut+, and amp+ versus ERBB2wt. No significant differences were observed in PD-L1 status between groups, while gLOH-high status was more common in amp+ versus ERBB2wt. MSI-high status was more frequent in KDmut+ versus ERBB2wt, and in ERBB2wt than in amp+.

CONCLUSIONS

We noted important differences in co-occurring GA in ERBB2-altered (ECDmut+, KDmut+, amp+) versus ERBB2wt UBC, as well as higher mean TMB and higher APOBEC mutational signature in the ERBB2-altered groups. Our results can help refine future clinical trial designs and elucidate possible response and resistance mechanisms for ERBB2-altered UBC.

Characterizing the Genomic Landscape of the Micropapillary Subtype of Urothelial Carcinoma of the Bladder Harboring Activating Extracellular Mutations of ERBB2

The micropapillary subtype of urothelial carcinoma (MPUC) of the bladder is a very aggressive histological variant of urothelial bladder cancer (UBC). A high frequency of MPUC contains activating mutations in the extracellular domain (ECD) of ERBB2. We sought to further characterize ERBB2 ECD-mutated MPUC to identify additional genomic alterations that have been associated with tumor progression and therapeutic response. In total, 5,485 cases of archived formalin-fixed, paraffin-embedded UBC underwent comprehensive genomic profiling to identify ERBB2 ECD-mutated MPUC and evaluate the frequencies of genomic co-alterations. We identified 219 cases of UBC with ERBB2 ECD mutations (74% S310F and 26% S310Y), of which 63 (28.8%) were MPUC. Genomic analysis revealed that TERT, TP53, and ARID1A were the most common co-altered genes in ERBB2-mutant MPUC (82.5%, 58.7%, and 39.7%, respectively) and did not differ from ERBB2-mutant non-MPUC (86.5%, 51.9%, and 35.3%). The main differences between ERBB2 ECD-mutated MPUC compared with non-MPUC were KMT2D, RB1, and MTAP alterations. KMT2D and RB1 are tumor-suppressor genes. KMT2D frequency was significantly decreased in ERBB2 ECD-mutated MPUC (6.3%) in contrast to non-MPUC (27.6%; P < .001). RB1 mutations were more frequent in ERBB2 ECD-mutated MPUC (33.3%) than in non-MPUC (17.3%; P = .012). Finally, MTAP loss, an emerging biomarker for new synthetic lethality-based anticancer drugs, was less frequent in ERBB2 ECD-mutated MPUC (11.1%) than in non-MPUC (26.9%; P = .018). Characterizing the genomic landscape of MPUC may not only improve our fundamental knowledge about this aggressive morphological variant of UBC but also has the potential to identify possible prognostic and predictive biomarkers that may drive tumor progression and dictate treatment response to therapeutic approaches.

[Morphological variants of the invasive urothelial cell carcinoma.]

Urothelial cell carcinoma is the most common malignant tumor of the urinary tract, which develops in the renal pelvis, ureter, and bladder, and rarely it develops in the ureter. Histologically, urothelial cell carcinoma is categorized into non-invasive and invasive forms. Non-invasive urothelial cell carcinoma has papillary growth, it is usually well differentiated, and has a favorable outcome, while invasive urothelial cell carcinoma infiltratively spreads the organs of origin, it is typically poorly differentiated, and often associated with a poor prognosis. In the case of invasive urothelial cell carcinoma, the clinical course is primarily determined by the depth of invasion, but according to recent data, morphological variants of urothelial cell carcinoma respond differently to oncological treatments, and their biological behavior is also distinct. These subtypes and variants are significantly underdiagnosed in Hungary and internationally because the criteria for histological diagnosis are not clear for many subsets. The latest 2022 WHO classification of urinary tract tumors significantly clarified the definitions of various subtypes and variants. In this paper, utilizing the current classification, we review and explain these subtypes' morphological, immunohistochemical, differential diagnostic, prognostic, and predictive characteristics intending to make them appear as much as possible in everyday diagnostic practice. Also, the work aims to present the individual urothelial cell carcinoma subtypes and variants to the Hungarian community of pathologists, oncologists, and urologists, so that the previously high level of urological oncology care can become even more personalized. Orv Hetil. 2023; 164(40): 1567-1582.

Phase II study of a trastuzumab biosimilar in combination with paclitaxel for HER2-positive recurrent or metastatic urothelial carcinoma: KCSG GU18-18

BACKGROUND

Human epidermal growth factor receptor 2 (HER2) is a widely explored therapeutic target in solid tumors. We evaluated the efficacy and safety of trastuzumab-pkrb, a biosimilar of trastuzumab, in combination with paclitaxel, in HER2-positive recurrent or metastatic urothelial carcinoma (UC).

PATIENTS AND METHODS

We enrolled 27 patients; they were administered a loading dose of 8 mg/kg trastuzumab-pkrb on day 1, followed by 6 mg/kg and 175 mg/m2 paclitaxel on day 1 every 3 weeks, intravenously. All patients received six cycles of the combination treatment and continued to receive trastuzumab-pkrb maintenance until disease progression, unacceptable toxicity, or for up to 2 years. HER2 positivity (based on immunohistochemistry analysis) was determined according to the 2013 American Society of Clinical Oncology /College of American Pathologists HER2 testing guidelines. The primary endpoint was objective response rate (ORR); the secondary endpoints were overall survival (OS), progression-free survival (PFS), and safety.

RESULTS

Twenty-six patients were evaluated via primary endpoint analysis. The ORR was 48.1% (1 complete and 12 partial responses) and the duration of response was 6.9 months [95% confidence interval (CI) 4.4-9.3 months]. With a median follow-up of 10.5 months, the median PFS and OS were 8.4 months (95% CI 6.2-8.8 months) and 13.5 months (95% CI 9.8 months-not reached), respectively. The most common treatment-related adverse event (TRAE) of any grade was peripheral neuropathy (88.9%). The most common grade 3/4 TRAEs were neutropenia (25.9%), thrombocytopenia (7.4%), and anemia (7.4%).

CONCLUSIONS

Trastuzumab-pkrb plus paclitaxel demonstrates promising efficacy with manageable toxicity profiles in patients with HER2-positive recurrent or metastatic UC.

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.

Nomograms for predicting survival in patients with micropapillary bladder cancer: a real-world analysis based on the surveillance, epidemiology, and end results database and external validation in a tertiary center

BACKGROUND

The present study aimed to construct and validate nomograms that can be used to predict cancer-specific survival (CSS) and overall survival (OS) in patients with micropapillary bladder cancer.

METHODS

The data of 627 patients diagnosed with micropapillary bladder cancer between 2000 and 2018 were obtained from the surveillance, epidemiology, and end results database. Patients were randomly divided into the training and internal validation sets (7:3). The Cox proportional hazards regression model was applied to evaluate the association between variables and survival and then nomograms were constructed to predict the survival of an individual patient. The performance of nomograms was validated by using calibration curves, concordance index, receiver operating characteristic curves with the calculated area under the curve and decision curve analysis in the training and internal validation set. Data from 41 micropapillary bladder cancer patients at Qilu Hospital of Shandong University from 2000 to 2022 were collected for external validation.

RESULTS

Several independent risk factors were taken into the two nomograms (CSS and OS), including age, marital status, AJCC TMN stage, surgical approach, lymph node ratio, and tumor size while the OS nomogram additionally contained race. The concordance index of the training set, internal validation set, and external verification set were all over 0.7. The calibration curve indicated good consistence between the nomogram prediction and actual survival. Area under the curve and decision curve analysis results indicated great clinical usefulness of nomograms.

CONCLUSIONS

The nomograms predicting the survival outcome of patients with micropapillary bladder cancer would provide a valuable tool to help clinicians to evaluate the risk of patients and make individual treatment strategies.

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.

Case report: Metastatic urothelial cancer with an exceptional response to immunotherapy and comprehensive understanding of the tumor and the tumor microenvironment

Although immune checkpoint inhibitors (ICIs) are increasingly used as second-line treatments for urothelial cancer (UC), only a small proportion of patients respond. Therefore, understanding the mechanisms of response to ICIs is critical to improve clinical outcomes for UC patients. The tumor microenvironment (TME) is recognized as a key player in tumor progression and the response to certain anti-cancer treatments. This study aims to investigate the mechanism of response using integrated genomic and transcriptomic profiling of a UC patient who was part of the KEYNOTE-045 trial and showed an exceptional response to pembrolizumab. Diagnosed in 2014 and receiving first-line chemotherapy without success, the patient took part in the KEYNOTE-045 trial for 2 years. She showed dramatic improvement and has now been free of disease for over 6 years. Recently described by Bagaev et al., the Molecular Functional (MF) Portrait was utilized to dissect genomic and transcriptomic features of the patient's tumor and TME. The patient's tumor was characterized as Immune Desert, which is suggestive of a non-inflamed microenvironment. Integrated whole-exome sequencing (WES) and RNA sequencing (RNA-seq) analysis identified an ATM mutation and high TMB level (33.9 mut/mb), which are both positive biomarkers for ICI response. Analysis further revealed the presence of the APOBEC complex, indicating the potential for use of APOBEC signatures as predictive biomarkers for immunotherapy response. Overall, comprehensive characterization of the patient's tumor and TME with the MF Portrait revealed important insights that could potentially be hypothesis generating to identify clinically useful biomarkers and improve treatment for UC patients.

Overview of histologic variants of urothelial carcinoma: current trends and narrative review on treatment outcomes

Background and Objective

The histologic variants of urothelial carcinoma (UC) are tumors arising from within the urothelium in which some component of the tumor morphology is other than urothelial. They are underdiagnosed, aggressive and have varying pathologic response rates to systemic chemotherapy. There are no consensus guidelines on the use of systemic chemotherapy in variant histology (VH) of UC. We performed a contemporary review on pathologic response rates to neoadjuvant systemic therapy and survival outcomes following radical cystectomy in order to provide a rationale for clinical practice recommendations on the management of UC with VH.

Methods

A PubMed literature search was conducted for all English articles from inception reporting either pathological response rates to neoadjuvant treatment or survival outcomes after radical cystectomy in non-metastatic VH of UC.

Key Content and Findings

Neoadjuvant chemotherapy (NAC) prior to radical cystectomy was shown to be a beneficial treatment strategy in UC with VH. The micropapillary, plasmacytoid, nested and sarcomatoid histologic variants were associated with worse survival outcomes compared to conventional UC and UC with squamous or glandular differentiation despite initial downstaging with chemotherapy. There is evidence of improved survival in patients with sarcomatoid differentiation receiving NAC compared to RC alone. The major prognostic factors that affect survival outcomes in VH of UC include histologic variant subtype, patient age, presence of lymphovascular invasion, hydronephrosis, nodal metastasis and advanced T stage at diagnosis. Recent studies demonstrate that VH of UC are heterogenous tumors and responsiveness to NAC may be a function of the molecular subtypes present.

Conclusions

Based on these findings, NAC to achieve pathologic downstaging prior to radical cystectomy is recommended for MIBC with VH. Biomarkers identified by molecular profiling with immunohistochemistry will need to be validated as predictors of response to NAC in future trials.

Clinicopathological Review of Micropapillary Urothelial Carcinoma

PURPOSE OF REVIEW

This review will discuss micropapillary urothelial carcinoma with respect to biology, histopathologic characteristics, genetic and molecular features, diagnosis, clinical management, and future directions of research.

RECENT FINDINGS

Recent consensus opinion study showed only moderate interobserver reproducibility in the diagnostic criteria. The most reproducible criteria with the highest consensus were multiple nests in the same lacunar spaces. There are recent reports of high rates of intratumoral heterogeneity of ERBB2 amplification within tumor containing both micropapillary and classic urothelial components. Micropapillary urothelial carcinoma is a well-documented highly aggressive variant of urothelial carcinoma with proven worse outcomes. Accurate recognition and reporting of this pattern is critical for optimal management. Newer therapeutic strategies related to the molecular and genetic findings seen in MPUC remain to be explored further.

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.

[Pathological and Molecular Features of Lung Micropapillary Adenocarcinoma]

肺微乳头腺癌作为高级别肺腺癌，具频发转移、淋巴结浸润、复发率高和总体生存率低的临床特征。该亚型肿瘤中存在特征致癌因子通路的激活和肿瘤免疫微环境的建立。本文拟对近年来微乳头腺癌的病理学表现及分子学特征研究进展作一综述，旨在加深对微乳头型病变的认识，进而为制定特异性治疗策略奠定基础。

Molecular pathology of urothelial carcinoma

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

Human epidermal growth factor receptor 2 (HER2) gene amplification in non-muscle invasive urothelial bladder cancers: Identification of patients for targeted therapy

Objectives

To evaluate human epidermal growth factor receptor 2 (HER2) protein overexpression by immunohistochemistry (IHC) and gene amplification by fluorescent in situ hybridisation (FISH) in urothelial non-muscle-invasive bladder carcinoma (NMIBC), as HER2 is a potential therapeutic target in muscle-invasive bladder carcinoma (MIBC) and HER2 expression and gene amplification in low/high-grade and pTa/pT1 NMIBC is not clear.

Patients and methods

The study included 93 bladder cancers; 25 MIBC and 68 NMIBC (37 low- and 31 high-grade). All HER2 positive (3+) and equivocal (2+) cases were subjected to FISH using a HER2/CEN 17 dual-colour probe kit. IHC and FISH were scored as per the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) 2013 Guidelines for breast cancers. Based on the number of signals/nuclei, amplification was categorised as low (≥6–10) and high-level (≥10).

Results

HER2 2–3+ expression was seen in 29% of NMIBCs (10.8% low- and 51.6% high-grade). HER2 3+ expression was seen in high-grade NMIBC (nine of 31; 29%) and MIBC (nine of 25; 36%). In all, 87% of high-grade NMIBCs were lamina invasive (pT1). Gene amplification was found in 45% (eight of 18) of 3+ tumours. None of the HER2 2+ tumours showed gene amplification. IHC and FISH results were in closest agreement when ≥50% of tumour cells showed 3+ expressions. High-level amplification correlated with increased gene expression on reverse transcriptase-polymerase chain reaction. On multivariate analysis, lower  stage, grade, and HER2 expression significantly correlated with progression-free survival. HER2 3+ expression in NMIBC correlated significantly with time to recurrence and progression.

Conclusion

Our present results show that HER2 FISH should not be performed for HER2 2 + and low-grade NMIBC. This contrasts with breast cancers where it is recommended for equivocal 2+ tumours. About 50% of HER2 3+ MIBC and high-grade NMIBC show HER2 gene amplification and can be potential candidates for HER2-targeted therapy.

Abbreviations

ASCO/CAP: American Society of Clinical Oncology/College of American Pathologists; DAB: 3,3ʹ-diaminobenzidine; FISH: fluorescent in situ hybridisation; HER2: human epidermal growth factor receptor 2; IHC: immunohistochemistry;(N)MIBC: (non-) muscle-invasive bladder carcinoma; MPUC: micropapillary variant of urothelial bladder cancer; PFS: progression-free survival; TURBT: transurethral resection of bladder tumour

Variant morphology and random chromosomal integration of BK polyomavirus in posttransplant urothelial carcinomas

BK polyomavirus (BKPyV) causes major complications in solid organ transplant recipients but little is known about its role in the development of urothelial carcinoma (UC) during immunosuppression. Immunohistochemistry (IHC) screening for polyomavirus large T antigen (LTag) was performed in 94 micropapillary UC (MPUC), 480 unselected UC, 199 muscle invasive UC (including 83 UC with variant differentiation), 76 cases of plasmocytoid, nested and large nested UC and 15 posttransplant UC. LTag expressing UC were reevaluated regarding their histomorphological features and characterized by IHC for p53 and HER2, chromogenic in situ hybridization for HER2 and SNaPshot analysis of the TERT promoter and HRAS. Real-time PCR and next generation sequencing (NGS) were performed to search for BKPyV-DNA and for variants in the tumor and viral genomes. We detected five LTag expressing UC which were diagnosed between 2 and 18 years after kidney (n = 4) or heart (n = 1) transplantation. 89 MPUC without history of organ transplantation and overall 755 UC (including cases with variant histology) were LTag negative. Of the five LTag expressing UC, three were MPUC, one showed extensive divergent differentiation with Mullerian type clear cell carcinoma, and one displayed focal villoglandular differentiation. All five tumors had aberrant nuclear p53 expression, 2/5 were HER2-amplified, and 3/5 had TERT promoter mutations. Within the 50 most common cancer related genes altered in UC we detected very few alterations and no TP53 mutations. BKPyV-DNA was present in 5/5 UC, chromosomal integration of the BKPyV genome was detectable in 4/5 UC. Two UC with BKPyV integration showed small deletions in the BKPyV noncoding control region (NCCR). The only UC without detectable BKPyV integration had a high viral load of human herpesvirus 6 (HHV-6). Our results suggest that LTag expression of integrated BKPyV genomes and resulting p53 inactivation lead to aggressive high-grade UC with unusual, often micropapillary morphology.

Cytological, histological, and molecular characteristics of pure invasive micropapillary carcinoma of pancreas: A case report

INTRODUCTION

Pure invasive micropapillary carcinoma (IMPC) is a rare histologic subtype of pancreatic cancer which has a high propensity for lymph node metastasis and poor prognosis.

PATIENT CONCERNS

An 81-year-old woman was admitted to our institution with a 3-month history of back pain. Computed tomography of the abdomen and pelvis confirmed the presence of a low-density mass in the tail of the pancreas.

DIAGNOSIS

Endoscopic ultrasound-guided fine needle aspiration cytology (FNAC) from the pancreatic mass showed small tumor cell clusters with three-dimensional aggregates and morula-like structures. The tumor was diagnosed as adenocarcinoma with micropapillary features.

INTERVENTIONS

The patient underwent radical antegrade modular pancreatosplenectomy and regional lymph node dissection. Histological examination showed small clusters of tumor cells that were closely adhered to one another. The cells were located in empty stromal spaces mimicking lymphovascular channels. All tumor cells showed reverse polarity, resulting in an "inside-out" pattern. An extensive search was performed, and no typical ductal adenocarcinoma component was found. The tumor measured 1.5 × 1.3 cm and invaded into the peripancreatic fat tissue without adjacent organ invasion. One of the 12 regional lymph nodes showed metastasis. Ion Torrent next-generation sequencing identified missense mutations in KRAS, TP53, and SMAD4 using the Oncomine Comprehensive Panel version 1.

OUTCOMES

Twelve months following surgical resection the patient remained healthy with no evidence of recurrence at clinical follow-up.

LESSONS

This report highlights the diagnostic features and molecular characteristics of pure pancreatic IMPC and the challenges with diagnosis by FNAC. A centralized and collaborative accumulation of additional cases of pure IMPC could further elucidate its pathogenesis.

Histologic Variants of Urothelial Carcinoma: Morphology, Molecular Features and Clinical Implications

Bladder cancer is a heterogeneous disease including conventional urothelial carcinoma (UC) and its histologic variants, and non-urothelial carcinoma, including squamous and glandular neoplasms. Urothelial carcinoma accounts for the majority of bladder cancer cases, but morphologic variants are common and include nested, microcystic, micropapillary, lymphoepithelioma-like, plasmacytoid, sarcomatoid, giant cell, undifferentiated, clear cell and lipoid. Certain variants of UC tend to be associated with a poor prognosis and have diagnostic and potential treatment implications that make the identification of variant histology crucial to clinical decision making. While there is still uncertainty regarding the prognostic implications of many of these variants, identifying and reporting variant histology is important to develop our understanding of their biology. Unique molecular features accompany many of these morphologic variants and to better understand these tumors, we review the molecular and clinical implications of histologic variants of bladder cancer. Major efforts are underway to include variant histology and divergent differentiation of UC in clinical trials to develop evidence based approaches to treatment. The purpose of this article is to review the current literature on variant histology of urothelial cancer and to highlight molecular findings and the clinical relevance of these tumors.

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.

Ado-trastuzumab emtansine (T-DM1) in patients with HER2-amplified tumors excluding breast and gastric/gastroesophageal junction (GEJ) adenocarcinomas: results from the NCI-MATCH trial (EAY131) subprotocol Q

BACKGROUND

The National Cancer Institute-Molecular Analysis for Therapy Choice (NCI-MATCH) is a national precision medicine study incorporating centralized genomic testing to direct refractory cancer patients to molecularly targeted treatment subprotocols. This treatment subprotocol was designed to screen for potential signals of efficacy of ado-trastuzumab emtansine (T-DM1) in HER2-amplified histologies other than breast and gastroesophageal tumors.

METHODS

Eligible patients had HER2 amplification at a copy number (CN) >7 based on targeted next-generation sequencing (NGS) with a custom Oncomine AmpliSeq™ (ThermoFisher Scientific) panel. Patients with prior trastuzumab, pertuzumab or T-DM1 treatment were excluded. Patients received T-DM1 at 3.6 mg/kg i.v. every 3 weeks until toxicity or disease progression. Tumor assessments occurred every three cycles. The primary end point was centrally assessed objective response rate (ORR). Exploratory end points included correlating response with HER2 CN by NGS. The impact of co-occurring genomic alterations and PTEN loss by immunohistochemistry were also assessed.

RESULTS

Thirty-eight patients were enrolled and 36 included in efficacy analysis. Median prior therapies in the metastatic setting was 3 (range 0-9; unknown in one patient). Median HER2 CN was 17 (range 7-139). Partial responses were observed in two (5.6%) patients: one mucoepidermoid carcinoma of parotid gland and one parotid gland squamous cell cancer. Seventeen patients (47%) had stable disease including 8/10 (80%) with ovarian and uterine carcinomas, with median duration of 4.6 months. The 6-month progression-free survival rate was 23.6% [90% confidence interval 14.2% to 39.2%]. Common toxicities included fatigue, anemia, fever and thrombocytopenia with no new safety signals. There was a trend for tumor shrinkage with higher levels of gene CN as determined by the NGS assay.

CONCLUSION

T-DM1 was well tolerated. While this subprotocol did not meet the primary end point for ORR in this heavily pre-treated diverse patient population, clinical activity was seen in salivary gland tumors warranting further study in this tumor type in dedicated trials.

ErbB2 Copy Number Aberration in Canine Urothelial Carcinoma Detected by a Digital Polymerase Chain Reaction Assay

Urothelial carcinoma (UC) is the most common tumor affecting the urinary bladder of dogs. Protein overexpression of ErbB2 (the canine homolog of HER2) has been observed in dogs with UC. However, no study regarding ErbB2 copy number aberration (CNA) is reported in dogs with UC. In this study, a digital PCR assay for detecting CNA of canine ErbB2 was developed. DNA samples were isolated from 83 formalin-fixed, paraffin-embedded urinary bladder tissues (36 UC, 8 polypoid cystitis, and 39 normal) and 94 urinary sediments (54 UC, 30 nonneoplastic, and 10 normal). The copy number of canine chromosome 8 (CFA8) was used as a control. In the urinary bladder tissues, ErbB2 CNA was detected in 12 of 36 (33%) UC, 2 of 8 (25%) polypoid cystitis, and 0 of 39 (0%) normal controls. In the urinary sediments, ErbB2 CNA was also detected in 19 of 54 (35%) UC; however, no ErbB2 CNA was detected in nonneoplastic diseases or normal controls. The sensitivity and specificity of ErbB2 CNA in urinary sediment for the detection of UC were 35% and 100%, respectively. There was a positive correlation between the copy number ratios of ErbB2 to CFA8 in the urinary bladder tissues and urinary sediments. Our findings indicate that the digital PCR assay of urinary sediments may be a useful, noninvasive method for detecting ErbB2 CNA in dogs with UC.

Glandular Tumors of the Urachus and Urinary Bladder: A Practical Overview of a Broad Differential Diagnosis

Primary glandular tumors of the urachus and urinary bladder are an intriguing group of clinically and morphologically diverse neoplasms for which there have been recent refinements in diagnostic subclassification and advances in molecular pathology. In addition, the urachus and urinary bladder may be secondarily involved by tumors with glandular differentiation that demonstrate remarkable morphologic, immunophenotypic, and molecular overlap. Thus, surgical pathologists need to be aware of the broad differential diagnosis of glandular tumors that involve the urachus and urinary bladder and have a practical diagnostic framework to evaluate these lesions in routine clinical practice. In this review, we summarize the salient clinical, morphologic, immunohistochemical, and molecular features of glandular tumors of the urachus and urinary bladder, including mucinous cystic tumors of the urachus, noncystic urachal adenocarcinomas, urothelial carcinomas with glandular or pseudoglandular features, primary urinary bladder adenocarcinomas, and Müllerian-type carcinomas, highlighting the strengths and limitations of various diagnostic features and ancillary tests, as well as the need for close clinical and radiographic correlation.

Formidable Scenarios in Urothelial and Variant Cancers of the Urinary Tract

Diagnostic and therapeutic challenges in the field of bladder and upper tract cancers provide opportunities for multidisciplinary care. Urothelial cancers make up the majority of the histologic subtype of bladder and upper tract cancers. Although the existence of variant histology, nonurothelial cancers, and urethral cancers is rare, these cancers pose a challenging clinical dilemma given the lack of well-defined consensus treatment guidelines. This review focuses on key issues of treatment: cisplatin ineligibility with emphasis on the definition, nuances of chemotherapy and frontline immune checkpoint inhibitor therapy, use of radiation in bladder-preservation strategies, upper tract urothelial cancer management, and highlights of urothelial variants and nonurothelial tumors and management.

Prognostic and therapeutic role of HER2 expression in micropapillary carcinoma of the bladder

Micropapillary carcinoma of the bladder (MPBC) is a variant type of infiltrating urothelial carcinoma, which portends a poor biological behavior in terms of disease stage at first diagnosis and clinical outcome; its peculiar morphology raises issues concerning the ability of tumor detection by imaging techniques and proper biopsy procedure, and the appropriate treatment for non-muscle infiltrating and muscle-infiltrating MPBC remains a matter of debate. On the basis of its established prognostic and therapeutic role in breast and gastro-esophageal cancer in the first instance, the human epidermal growth factor receptor-2 (HER2) has been investigated in selected case series of MPBC over the last 10 years. The aim of the present review was to summarize the existing evidence on HER2 status in MPBC, and to discuss its present and future utility in risk assessment and treatment choice of this uncommon, yet aggressive, disease.

Updates on the Genetics and Molecular Subtypes of Urothelial Carcinoma and Select Variants

Urothelial carcinoma is a morphologically and genomically heterogeneous disease that exhibits a wide spectrum of morphologic features and molecular alterations and subtypes. Classic urothelial carcinoma (not otherwise specified) is the most common tumor type that develops in the urinary bladder but many, well-documented, variant histologies are commonly encountered in approximately one-third of invasive urothelial carcinoma, including squamous, glandular, micropapillary, sarcomatoid, small cell/neuroendocrine, clear cell, lymphoepithelioma-like, and plasmacytoid types, among others. In this review, we provide an update on the molecular advances in urothelial carcinoma and some of its variant histologies.

Reappraisal of HER2 status in the spectrum of advanced urothelial carcinoma: a need of guidelines for treatment eligibility

Although human epidermal growth factor receptor 2 (HER2) may represent a therapeutic target, its evaluation in urothelial carcinoma of the bladder does not rely on a standardized scoring system by immunohistochemistry or fluorescent in situ hybridization (FISH), as reflected by various methodology in the literature and clinical trials. Our aim was to improve and standardize HER2 amplification detection in bladder cancer. We assessed immunohistochemical criteria derived from 2013 American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAPs) guidelines for breast cancer and investigated intratumoral heterogeneity in a retrospective multicentric cohort of 188 patients with locally advanced urothelial carcinoma of the bladder. Immunohistochemistry was performed on 178 primary tumors and 126 lymph node metastases, eligible cases (moderate/strong, complete/incomplete membrane staining) were assessed by FISH. HER2 overexpression was more frequent with 2013 ASCO/CAP than 2007 ASCO/CAP guidelines (p < 0.0001). The rate of positive HER2 FISH was similar between primary tumor and lymph node metastases (8%). Among positive FISH cases, 48% were associated with moderate/strong incomplete membrane staining that were not scored eligible for FISH by 2007 ASCO/CAP criteria. Among 3+ immunohistochemistry score cases, 67% were associated with HER2-positive FISH. Concordance between primary tumors and matched lymph node metastases was moderate for immunohistochemistry (κ = 0.54 (CI 95%, 0.41-0.67)) and FISH (κ = 0.50 (CI 95%, 0.20-0.79)). HER2-positive FISH was more frequent in micropapillary carcinomas (12%) and carcinoma with squamous differentiation (11%) than in pure conventional carcinoma (6%). Intratumoral heterogeneity for HER2 immunohistochemistry was observed in 7% primary tumor and 6% lymph node metastases; 24% positive HER2 FISH presented intratumoral heterogeneity. Our study suggests that HER2 evaluation should include an immunohistochemistry screening step with eligibility for FISH including incomplete/complete and moderate/strong membrane staining. Spatial or temporal intratumoral heterogeneity prompts to perform evaluation on both tumor and lymph node, and for each histological variant observed.

Urinary Bladder Pathology: World Health Organization Classification and American Joint Committee on Cancer Staging Update

Context.—

Since the publication of the previous World Health Organization (WHO) Classification of Tumours on the Pathology and Genetics of Tumours of the Urinary System and Male Genital Organs in 2004, significant new knowledge has been generated regarding the pathology and genetics of bladder neoplasia. Publication of the 2016 WHO “Blue Book” has codified that new data into updated recommendations for classification and prognostication. Similarly, the recent release of the 8th edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual, which was implemented in January 2018, has also addressed staging criteria for bladder cancer in several unique settings to clarify their application.

Objective.—

To highlight subtle changes within the recent WHO and AJCC publications that may affect daily surgical pathology practice.

Data Sources.—

Peer-reviewed published literature, the 2016 WHO Classification of Tumours of the Urinary System and Male Genital Organs, and the 8th edition of the AJCC Cancer Staging Manual were reviewed.

Conclusions.—

Selected changes and/or clarifications are discussed and include classification of flat and papillary urothelial neoplasia, select variant patterns of invasive urothelial carcinoma, staging of invasive carcinoma in bladder diverticula, and staging of carcinomas involving the prostate gland.

Intratumoral heterogeneity of ERBB2 amplification and HER2 expression in micropapillary urothelial carcinoma

Micropapillary urothelial carcinoma (MPUC) is a rare but an aggressive variant of urothelial carcinoma. MPUC has been shown to commonly exhibit ERBB2 amplification and HER2 protein overexpression, but the frequency and distribution of these findings within micropapillary (MP) and not otherwise specified (NOS) components of tumors with mixed histology have not been addressed. Therefore, we evaluated ERBB2 amplification and HER2 expression in 43 MPUC cases by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC). Of the 35 tumors containing both MP and NOS components, ERBB2 amplification was present in both the MP and NOS components of 12 tumors (34.3%), in only the MP component of 11 tumors (31.4%), and exclusively in the NOS component of 4 tumors (11.4%). HER2 protein overexpression was significantly more commonly present in the MP component compared to the NOS component within the same tumor (68.6% versus 34.3%, P = .012). Overall, there was a moderately positive correlation between HER2 protein expression and ERBB2 amplification in both MP (ρ = 0.59, P < .001) and NOS (ρ = 0.70, P < .001) components. All MP/NOS areas with IHC score 3+ and none of MP/NOS areas with IHC score 0 were associated with ERBB2 amplification. We conclude that ERBB2 amplification and HER2 overexpression are preferentially but not exclusively identified in the MP component compared to the NOS component within the same tumor. Our findings identify the presence of intratumoral heterogeneity of ERBB2 amplification and HER2 expression in MPUC and provide grounds for further investigation into the mechanisms underlying the development of MPUC.

High-Grade Urothelial Carcinoma of Bladder Transforming to Micropapillary Variant on Follow-Up

Micropapillary variant of urothelial carcinoma (UC) of the bladder is an aggressive tumour, comprising 0.6-6% of all UC. It generally presents with high-grade and stage, and has been reported as having a worse prognosis when compared to traditional UC. We report the case of a 58-year-old man who presented with macroscopic haematuria. The patient was diagnosed with high-grade urothelial carcinoma and returned with recurrence after 16 months. Histopathology after transurethral biopsy revealed a non-muscle invasive high-grade bladder tumour at first presentation, whereas tumour recurrence was reported after 1.5years. The histopathology at recurrence revealed a high-grade, muscle invasive, micropapillary variant of urothelial carcinoma with focal adenomatous morphology. Immunohistochemical expression of CK7⁺/CK20⁺ in tumour cells and negativity for PSA, AMACR, and CDX2 in paraffin section helped in identifying the tumour as primary in the urinary bladder. Radical cystectomy was performed and the patient has no distant metastases on follow-up. The specific morphology even within the high-grade urothelial cancer cases is important to discern for proper treatment.

Micropapillary morphology is an indicator of poor prognosis in patients with urothelial carcinoma treated with transurethral resection and radiochemotherapy

Purpose of this study was to evaluate prognostic impact of rare variants of urothelial bladder cancer (BC) after treatment with combined radiochemotherapy (RCT). To this end tumour tissue of 238 patients with urothelial carcinoma (UC) treated with transurethral resection of the bladder (TUR-B) and RCT with curative intent was collected. Histomorphological analysis included re-evaluation and semi-quantitative assessment of rare UC subtypes. Additionally, human epidermal growth factor receptor 2 (HER2) chromogenic in situ hybridisation (CISH) was performed in tumours with a micropapillary component exceeding 30 %. Long-term follow-up was available for 200 patients (range 3-282 months). Variant UC histology was found in 45 of 238 tumours, most frequently micropapillary UC (N = 17) including cases with a small fraction of tumour with micropapillary morphology. The mere presence of micropapillary morphology did not affect prognosis. In tumours with extensive (≥30 %) micropapillary morphology (N = 8) Kaplan-Meier analysis revealed significantly worse cancer specific survival (CSS) (P = 0.002) compared to conventional UC (mean survival times 97 months and 229 months, respectively). Univariate Cox regression analysis of cases with ≥30 % micropapillary morphology revealed a hazard ratio of 4.726 (95 % CI 1.629-13.714) for CSS (P = 0.004). CISH revealed HER2 gene amplification in 3/10 tumours with ≥30 % micropapillary component. In conclusion, for BC treated with TUR-B and RCT, the presence of micropapillary morphology in more than 30 % of the tumour is an adverse prognostic factor. Further studies are needed to evaluate a potential benefit of different, especially multimodal treatment strategies for micropapillary UC and also other subtypes of UC. Her2 represents a promising therapeutic target in a subset of micropapillary UC.

Consensus and conflict in invasive micropapillary carcinoma: a case report and review of the literature

Invasive micropapillary carcinoma (IMPC) is an aggressive histologic subtype of adenocarcinoma that has been gaining increased attention over the past twenty years. It is important to recognize IMPC due to its strong association with early lymphovascular invasion (LVI), high risk of lymph node metastasis, perineural invasion and poor prognosis. Controversies regarding IMPC include differentiating from retraction artifact and mimics, clinical significance of proportion of micropapillary component (MC), pathogenesis, biologic nature of the entity and consequently terminology, etc. We herein present a case of rectal IMPC arising from a tubulovillous adenoma. Since HER2 over-expression has been reported in IMPC of the breast and the bladder but never in the colorectum, given the availability of HER2 targeted therapy, HER2 protein expression in our case is examined by immunohistochemical study which shows weak incomplete membrane staining in less than 5% of cells. Literature is reviewed with emphasis on colorectal IMPC as well as aforementioned controversial topics. In summary, more study is needed to resolve the conflicts and build consensus on IMPC.