PD-L1 Immunohistochemistry Assay Concordance in Urothelial Carcinoma of the Bladder and Hypopharyngeal Squamous Cell Carcinoma

Comparative evaluation of PD-L1 expression and tumor immune microenvironment in molecular subtypes of muscle-invasive bladder cancer and its correlation with survival outcomes

OBJECTIVES

Immune checkpoint inhibitors have revolutionized treatment of platinum-refractory advanced bladder cancer, offering hope where options are limited. Response varies, however, influenced by factors such as the tumor's immune microenvironment and prior therapy. Muscle-invasive bladder cancer (MIBC) is stratified into molecular subtypes, with distinct clinicopathologic features affecting prognosis and treatment. This study assessed the expression of programmed cell death 1 ligand 1 (PD-L1) and other immune markers in MIBC, categorized by molecular phenotype.

METHODS

Using GATA3 and CK5/6 immunohistochemistry, 90 neoadjuvant chemotherapy-naive MIBC cases were classified into luminal and non-luminal subtypes. The immune microenvironment was characterized through immunostaining for PD-L1, CD4, and CD8. We applied PD-L1 positivity thresholds of 1% or greater for tumor cells and 5% or greater for immune cells. Tumors were examined for PD-L1 expression, histologic subtypes, and immune cell infiltration.

RESULTS

Varied expression of PD-L1 and T-cell subtype densities were observed among MIBC subtypes. The double-negative subtype displayed the highest PD-L1 immune cell expression and stromal CD4 and CD8 T-cell densities, indicating an active immune profile. The basal subtype exhibited the highest PD-L1 positivity in tumor cells. In contrast, the luminal type showed the lowest PD-L1 tumor and immune cell expression, with high intratumoral CD4 T-cell density. Although PD-L1 expression in tumor or immune cells did not independently affect survival, patients with basal and double-negative tumors had poorer overall survival.

CONCLUSIONS

This study highlighted the immune diversity of MIBC in the context of molecular subtypes. Distinct molecular and immune profiles could guide the development of predictive signatures for enhanced immunotherapy response in advanced bladder cancer.

Comparison of PD-L1 assays in head and neck carcinoma

Programmed cell death-ligand 1 (PD-L1) expression is a predictive biomarker for response to immune checkpoint inhibitor in head and neck squamous cell carcinoma. Given the range of antibodies and platforms for PD-L1 testing, it is essential to understand the performance of different staining and scoring methods. PD-L1 expression in 156 head and neck mucosal squamous cell carcinoma (HNmSCC) cases at Asan Medical Center was assessed using 106 tissue microarray (TMA) cores and 50 whole slides. Three standardised PD-L1 assays (22C3 pharmDx, SP263, and 28-8 pharmDx) and one laboratory-developed test (22C3 LDT) were evaluated: the combined positive score (CPS) with ≥1, ≥20, and ≥50 cut-offs, and the tumour positive score (TPS) with ≥1%, ≥20%, ≥50% cut-offs. Concordance on a continuous scale among the assays was good to excellent for CPS [intraclass correlation coefficient (ICC) range 0.73-0.94] and TPS (ICC range 0.70-0.94) and in both TMA and whole slides cohorts. Stratification by variable cut-offs demonstrated moderate to good agreement among most assays, as analysed by Gwet's AC1. PD-L1 expression was significantly correlated with tumour location using the 22C3 pharmDx assay (CPS, p=0.014; TPS, p=0.033). Notable concordance was found among PD-L1 assays, suggesting their potential interchangeability in HNmSCC.

Concordance of PD-L1 Expression in Metastatic Triple-negative Breast Cancer Between the 22C3 and E1L3N Antibodies Using Combined Positive Scoring

For patients with metastatic triple-negative breast cancer (TNBC), treatment with pembrolizumab is dependent on the accurate determination of programmed death ligand 1 (PD-L1) expression using immunohistochemistry (IHC). This study evaluated the interobserver concordance in assessing PD-L1 expression on TNBC samples using the commercial 22C3 IHC assay and an in-house assay based on the E1L3N antibody. Concordance between the 22C3 and the E1L3N IHC assays was evaluated on TNBC samples read by a commercial laboratory and a Brigham and Women's Hospital breast pathologist (BWH reader). Each slide was given a PD-L1 combined positive score (CPS) and was considered PD-L1 positive or negative based on the CPS cutoff of 10. Interobserver concordance for the assays was also evaluated on a subset of samples between 2 and 3 independent readers. On 71 samples, 2 independent readers (1 BWH reader and commercial laboratory) using E1L3N and 22C3, respectively, reached agreement on PD-L1 status (positive/negative) on 64 samples (90.1%). Using 22C3, 2 independent readers reached agreement on PD-L1 status on 30 of 36 samples (83.3%), and 3 independent readers reached agreement on 16 of 27 samples (59.3%). Using E1L3N, 2 BWH readers reached agreement on PD-L1 status on 18 of 27 samples (66.7%). Three BWH readers reached an agreement on 2 of 12 of the most challenging samples (16.7%). In conclusion, concordance between E1L3N and 22C3 testing using CPS for PD-L1 in metastatic TNBC was >90%. However, certain cases were challenging to agree upon using current threshold criteria, highlighting the need for more standardized evidence-based methods to assess PD-L1 expression.

PD-L1 expression in squamous cervical carcinomas of Mozambican women living with or without HIV

Programmed death-ligand 1 (PD-L1) is overexpressed in squamous cervical cancer (SCC) and can be used for targeted immunotherapy. The highest mortality rates of SCC are reported in sub-Saharan Africa, where Human immunodeficiency virus (HIV) prevalence is high. In Mozambique most SCC patients present at advanced stages. Thus, there is a need to introduce new treatment options. However, immunocompromised patients were frequently excluded in previous clinical trials. Our aim was to determine if PD-L1 expression in SCC is as prevalent among women living with HIV (WLWH) as among other patients. 575 SCC from Maputo Central Hospital were included. HIV status was available in 266 (46%) cases PD-L1 expression was scored through tumour proportion score (TPS) and combined positive score (CPS). PD-L1 was positive in 20.1% of the cases (n = 110), TPS (score ≥ 25%) and in 26.3% (n = 144), CPS (score ≥ 1). Stratifying according to the HIV status, WLWH were TPS positive in 16.7%, compared to 20.9%, p = 0.43, and concerning CPS 21.1% versus 28.7%, p = 0.19, respectively. PD-L1 status was not influenced by stage, Ki-67 or p16, CD8 expression influenced only CPS status. Our data indicates that the documented effect of PD-L1 therapy on SCC should be confirmed in randomized clinical trials in an HIV endemic milieu.

Principles of Analytic Validation of Immunohistochemical Assays: Guideline Update

CONTEXT.—

In 2014, the College of American Pathologists developed an evidence-based guideline to address analytic validation of immunohistochemical assays. Fourteen recommendations were offered. Per the National Academy of Medicine standards for developing trustworthy guidelines, guidelines should be updated when new evidence suggests modifications.

OBJECTIVE.—

To assess evidence published since the release of the original guideline and develop updated evidence-based recommendations.

DESIGN.—

The College of American Pathologists convened an expert panel to perform a systematic review of the literature and update the original guideline recommendations using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS.—

Two strong recommendations, 1 conditional recommendation, and 12 good practice statements are offered in this updated guideline. They address analytic validation or verification of predictive and nonpredictive assays, and recommended revalidation procedures following changes in assay conditions.

CONCLUSIONS.—

While many of the original guideline statements remain similar, new recommendations address analytic validation of assays with distinct scoring systems, such as programmed death receptor-1 and analytic verification of US Food and Drug Administration approved/cleared assays; more specific guidance is offered for validating immunohistochemistry performed on cytology specimens.

Concordance between four PD-L1 immunohistochemical assays and 22C3 pharmDx assay in esophageal squamous cell carcinoma in a multicenter study

Background

The prediction of response to immunotherapy mostly depends on the programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) status, and the 22C3 pharmDx assay has been approved in esophageal squamous cell carcinoma (ESCC). However, the widespread use of the 22C3 pharmDx assay is limited due to its availability. Thus, alternative PD-L1 assays are needed. We aimed to investigate the analytical and clinical diagnostic performances of four PD-L1 assays and to compare their concordances with the 22C3 pharmDx assay.

Methods

The PD-L1 22C3 pharmDx assay was performed on the Dako Autostainer Link 48 platform, three testing assays (PD-L1 E1L3N XP antibody [Ab], PD-L1 BP6099 Ab and PD-L1 CST E1L3N Ab) on the Leica BOND-MAX/III platform, and one testing assay (PD-L1 MXR006 Ab) on the Roche VENTANA Benchmark Ultra platform. A total of 218 ESCC cases from four centers were included in this retrospective study. Professionals from each center stained and read the IHC slides independently and determined the combined positive score (CPS) and the tumor proportion score (TPS).

Results

Regarding analytical performance, the four testing assays demonstrated good correlations with the 22C3 pharmDx assay when evaluated by the TPS or CPS (ρ > 0.8 for all four assays). Regarding diagnostic performance (CPS ≥ 10 was used as the cutoff), the four testing assays showed moderate concordances with the 22C3 pharmDx assay (kappa > 0.7 for all four assays). The overall percent agreements between each testing assay and the 22C3 pharmDx assay was at least 87.2 %.

Conclusion

This study provides insight into the potential interchangeability of the four PD-L1 assays with the 22C3 pharmDx assay.

Integrating the PD-L1 Prognostic Biomarker in Non-Muscle Invasive Bladder Cancer in Clinical Practice-A Comprehensive Review on State-of-the-Art Advances and Critical Issues

Bladder cancer (BC) is one of the most prevalent cancers worldwide. Non-muscle invasive bladder cancer (NMIBC), comprising the majority of initial BC presentations, requires accurate risk stratification for optimal management. This review explores the evolving role of programmed cell death ligand 1 (PD-L1) as a prognostic biomarker in NMIBC, with a particular focus on its implications in the context of Bacillus Calmette-Guérin (BCG) immunotherapy. The literature suggests a potential association between elevated PD-L1 status and adverse outcomes, resistance to BCG treatment, and disease progression. However, conflicting findings and methodological issues highlight the heterogeneity of PD-L1 assessment in NMIBC, probably due to the complex biological mechanisms that regulate the interaction between PD-L1 and the tumor microenvironment. The identification of PD-L1 as a prognostic biomarker provides ground for tailored therapeutic interventions, including immune checkpoint inhibitors (ICIs). Nevertheless, challenges such as intratumoral heterogeneity and technical issues underscore the need for standardized protocols and larger, homogeneous trials. This review contributes to the ongoing debate on the personalized management of NMIBC patients, focusing on the advances and perspectives of incorporating PD-L1 as a biomarker in this setting.

PD-L1 testing in metastatic triple-negative breast cancer: Interobserver and interplatform reproducibility of CE-IVD assays for CPS and IC scores

PD-L1 test is recommended in different types of tumors to select patients eligible for immune checkpoint inhibitors (ICI) therapy. Several factors make this test challenging in metastatic triple-negative breast cancer (mTNBC). Different assays and platforms are available, each associated with distinct scoring systems and threshold values specific to the ICI compound used, i.e. CPS≥10 for pembrolizumab and IC ≥ 1 % for atezolizumab. Our objective was to assess the consistency of PD-L1 testing in mTNBC by examining interobserver and interassay reproducibility. We assessed n = 60 mTNBC samples for PD-L1 testing using 22C3 pharmDx assay on a Dako Autostainer Link 48 and VENTANA PD-L1 (SP263) on a Ventana BenchMark Ultra. Additionally, a subset of n = 19 samples was tested using the SP142 assay, also on the Ventana BenchMark Ultra. CPS with both 22C3 and SP263 was independently evaluated by five pathologists, all certified PD-L1 trainers. The IC with SP142 was assessed by three of these pathologists, who have particular expertise in breast pathology. Following the computation of the intraclass correlation coefficient (ICC) for each assay and their respective thresholds, we assessed the agreement between different raters and assays using Fleiss's κ, with a 95 % confidence interval (CI). Overall, we observed a significant (p < 0.001) ICC with both CPS assays [22C3 = 0.939 (CI:0.913-0.96); SP263 = 0.972 (CI:0.96-0.982); combined 22C3-SP263 = 0.909 (CI:0.874-0.938)]. Fleiss's κ confirmed an almost perfect agreement among pathologists and assays: 22C3 = 0.938 (CI:0.857-1.018); SP263 = 0.972 (CI:0.890-1.052); combined 22C3-SP263 = 0.907 (CI:0.869-0.945). Perfect inter-rater agreement was reached considering IC. This study establishes the reliability of assessing CPS in mTNBC using either the 22C3 pharmDx, as employed in the KEYNOTE studies, or the VENTANA SP263 assay. Each assay must be used on its designated platform, namely the Dako for 22C3 pharmDx and the Ventana for VENTANA SP263. It is important to remark that CPS and IC identify different patient cohorts and, therefore, are not interchangeable.

Concordance of assessments of four PD-L1 immunohistochemical assays in esophageal squamous cell carcinoma (ESCC)

OBJECTIVE

Given real-world limitations in programmed death-ligand 1 (PD-L1) testing, concordance studies between PD-L1 assays are needed. We undertook comparisons of PD-L1 assays (DAKO22C3, Ventana SP263, Ventana SP142, E1L3N) among observers in esophageal squamous cell carcinoma (ESCC) to provide information on the analytical and clinical comparability of four PD-L1 IHC assays.

METHODS

Paraffin embedded samples of 50 cases of esophageal squamous cell carcinoma were obtained, satined with all four PD-L1 assays. PD-L1 was evaluated by 68 pathologists from 19 different hospitals. PD-L1 expression was assessed for combined positive score (CPS).

RESULTS

The expression sensitivity of SP263 was the highest in ESCC, followed by 22C3, E1L3N and SP142. Taking CPS 10 as the critical value, inter-observer concordance for CPS scores among 68 physicians was assessed for the 22C3, SP263, SP142, and E1L3N assays, yielding values of 0.777, 0.790, 0.758, and 0.782, respectively. In the comparison between assays, the overall CPS scores concordance rates between 22C3 and SP263, SP142, and E1L3N were 0.896, 0.833, and 0.853, respectively. 22C3 and SP263 have high concordance, with OPA of 0.896, while E1L3N and SP142 have the highest concordance, with OPA of 0.908.

CONCLUSION

In ESCC, the concordance of PD-L1 evaluation among observers is good, and the immune cell score is still an important factor affecting the concordance of interpretation among observers. Cases near the specific threshold are still the difficult problem of interpretation. SP263 had the highest CPS score of the four assays. SP263 cannot identify all 22C3 positive cases, but had good concordance with 22C3.E1L3N and SP142 showed high concordance.

Assessing PD-L1 Expression in Head and Neck Squamous Cell Carcinoma: Trials and Tribulations

Immune checkpoint inhibitors have improved the outcome of patients diagnosed with inoperable recurrent or metastatic head and neck squamous cell carcinoma. However, as only a subset of head and neck cancer patients benefit from this treatment, biomarkers predicting treatment response help guide physicians in their clinical decision-making. PD-L1 expression assessed by immunohistochemistry is the single most clinically relevant biomarker predicting response to PD-1-blocking antibodies. Here, we discuss in which clinical context assessment of PD-L1 expression is instrumental for the choice of therapy, how pathologists score it, and how it affects the approval of anti-PD-1 antibodies. Furthermore, we discuss the heterogeneity of PD-L1 expression and review technical aspects of determining this prominent biomarker-knowledge that might influence clinical decision-making.

Clinical-genomic determinants of immune checkpoint blockade response in head and neck squamous cell carcinoma

BACKGROUNDRecurrent and/or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) is generally an incurable disease, with patients experiencing median survival of under 10 months and significant morbidity. While immune checkpoint blockade (ICB) drugs are effective in approximately 20% of patients, the remaining experience limited clinical benefit and are exposed to potential adverse effects and financial costs. Clinically approved biomarkers, such as tumor mutational burden (TMB), have a modest predictive value in HNSCC.METHODSWe analyzed clinical and genomic features, generated using whole-exome sequencing, in 133 ICB-treated patients with R/M HNSCC, of whom 69 had virus-associated and 64 had non-virus-associated tumors.RESULTSHierarchical clustering of genomic data revealed 6 molecular subtypes characterized by a wide range of objective response rates and survival after ICB therapy. The prognostic importance of these 6 subtypes was validated in an external cohort. A random forest-based predictive model, using several clinical and genomic features, predicted progression-free survival (PFS), overall survival (OS), and response with greater accuracy than did a model based on TMB alone. Recursive partitioning analysis identified 3 features (systemic inflammatory response index, TMB, and smoking signature) that classified patients into risk groups with accurate discrimination of PFS and OS.CONCLUSIONThese findings shed light on the immunogenomic characteristics of HNSCC tumors that drive differential responses to ICB and identify a clinical-genomic classifier that outperformed the current clinically approved biomarker of TMB. This validated predictive tool may help with clinical risk stratification in patients with R/M HNSCC for whom ICB is being considered.FUNDINGFundación Alfonso Martín Escudero, NIH R01 DE027738, US Department of Defense CA210784, The Geoffrey Beene Cancer Research Center, The MSKCC Population Science Research Program, the Jayme Flowers Fund, the Sebastian Nativo Fund, and the NIH/NCI Cancer Center Support Grant P30 CA008748.

[Practical aspects of PD-L1 assessment in the treatment of urothelial carcinoma: Consensus of the uropathology group of the SEAP]

The recent addition of novel immunotherapy drugs for the treatment of urothelial carcinoma makes it necessary the establishment of criteria to harmonize the immunohistochemical assessment of PD-L1, both as a prognostic factor and for the selection of patients to be treated. In this scenario, a group of uropathologists from the Spanish Society of Pathological Anatomy, together with a medical oncologist as an external collaborator subspecialized in uro-oncology, have prepared this document of recommendations based on the available evidence. During PD-L1 assessment it is especially relevant the selection of the sample, its processing, the immunohistochemical platform and antibody used, and the algorithm applied in the interpretation of results. All these aspects must be indicated in the results report, which should be easily interpretable in a context of rapid evolution of immunological therapies.

Role of Surgical Pathologist for Detection of Immunooncologic Predictive Factors in Head and Neck Cancer

Immunotherapy has shown promising results in the treatment of recurrent and metastatic head and neck cancers. Antiprogrammed cell death (PD)-1 therapies have been recently approved in this setting and they are currently tested also in the treatment of locally advanced diseases and in the neoadjuvant setting. However, the clinical benefits of these treatments have been quite variable, hence the need to select those patients who may obtain the maximal efficacy through the identification of predictive biomarkers. Currently, PD-L1 immunohistochemical expression by tumor and immune cells is the most widely used predictive biomarker for immunotherapy in head and neck squamous cell carcinoma. Nevertheless, patients with PD-L1 - tumors may still respond to treatments, thereby emphasizing the need for the identification of other predictive biomarkers. In this review, we summarize the current data on histologic and molecular parameters that can be used to select patients with head and neck cancers for immunotherapy, with a focus on squamous cell carcinoma and salivary gland carcinomas.

The Ring Study: an international comparison of PD-L1 diagnostic assays and their interpretation in non-small cell lung cancer, head and neck squamous cell cancer and urothelial cancer

PD-L1 immunohistochemistry has been approved as a diagnostic assay for immunotherapy. However, an international comparison across multiple cancers is lacking. This study aimed to assess the performance of PD-L1 diagnostic assays in non-small cell lung cancer (NSCLC), head and neck squamous cell cancer (HNSCC) and urothelial cancer (UC). The excisional specimens of NSCLC, HNSCC and UC were assayed by Ventana SP263 and scored at three sites in each country, including Australia, Brazil, Korea, Mexico, Russia and Taiwan. All slides were rotated to two other sites for interobserver scoring. The same cohort of NSCLC was assessed with Dako 22C3 pharmDx PD-L1 for comparison. The PD-L1 immunopositivity was scored according to the approved PD-L1 scoring algorithms which were the percentage of PD-L1-expressing tumour cell (TC) and tumour proportion score (TPS) by Ventana SP263 and Dako 22C3 staining, respectively. In NSCLC, the comparison demonstrated the comparability of the SP263 and 22C3 assays (cut-off of 1%, κ=0.71; 25%, κ=0.75; 50%, κ=0.81). The interobserver comparisons showed moderate to almost perfect agreement for SP263 in TC staining at 25% cut-off (NSCLC, κ=0.72 to 0.86; HNSCC, κ=0.60 to 0.82; UC, κ=0.68 to 0.91) and at 50% cut-off for NSCLC (κ=0.64 to 0.90). Regarding the immune cell (IC) scoring in UC, there was a lower correlation (concordance correlation coefficient=0.10 to 0.68) and poor to substantial agreements at the 1%, 5%, 10% and 25% cut-offs (κ= -0.04 to 0.76). The interchangeability of SP263 and 22C3 in NSCLC might be acceptable, especially at the 50% cut-off. In HNSCC, the performance of SP263 is comparable across five countries. In UC, there was low concordance of IC staining, which may affect treatment decisions. Overall, the study showed the reliability and reproducibility of SP263 in NSCLC, HNSCC and UC.

Urine PD-L1 is a tumor tissue candidate substitute and is associated with poor survival in muscle-invasive bladder cancer patients

Programmed death molecule ligand 1 (PD-L1) expression in urothelial carcinoma is a predictive marker used to guide immunotherapy. As expression of PD-L1 may be heterogeneous in the tumor tissue space, it cannot be accurately determined by immunohistochemical analysis. In this study, we examined PD-L1 protein levels in preoperative urine samples from bladder cancer patients, evaluated the prevalence of PD-L1 in urine, examined the usefulness of urine as a surrogate for PD-L1 expression in tumors, and compared PD-L1 expression in postoperative pathological sections. We found that PD-L1 in urine and tumor tissue correlated well and that it may be able to some extent serve as a surrogate for tissues in bladder cancer and thus predict risk of recurrence in muscle-invasive bladder cancer (MIBC) patients. Our findings reveal the clinical relevance of urine PD-L1 as a noninvasive prognostic indicator for immunotherapy and offer clinical translational suggestions for eventual development of a prognostic model for immunotherapy for bladder cancer.

The 2022 World Health Organization Classification of Tumors of the Urinary System and Male Genital Organs-Part B: Prostate and Urinary Tract Tumors

The 2022 World Health Organization (WHO) classification of the urinary and male genital tumors was recently published by the International Agency for Research on Cancer. This fifth edition of the WHO "Blue Book" offers a comprehensive update on the terminology, epidemiology, pathogenesis, histopathology, diagnostic molecular pathology, and prognostic and predictive progress in genitourinary tumors. In this review, the editors of the fifth series volume on urologic and male genital neoplasms present a summary of the salient changes introduced to the classification of tumors of the prostate and the urinary tract.

Programmed Cell Death-Ligand-1 expression in Bladder Schistosomal Squamous Cell Carcinoma – There’s room for Immune Checkpoint Blockage?

Schistosoma haematobium, the causative agent of urogenital schistosomiasis, is a carcinogen type 1 since 1994. It is strongly associated with bladder squamous-cell carcinoma in endemic regions, where it accounts for 53-69% of bladder-carcinoma cases. This histological subtype is associated with chronic inflammation being more aggressive and resistant to conventional chemo and radiotherapy. Immune-Checkpoint-Blockage (ICB) therapies targeting the Programmed-Cell-Death-Protein-1(PD-1)/Programmed-Cell-Death-Ligand-1(PD-L1) axis showed considerable success in treating advanced bladder urothelial carcinoma. PD-L1 is induced by inflammatory stimuli and expressed in immune and tumor cells. The binding of PD-L1 with PD-1 modulates immune response leading to T-cell exhaustion. PD-L1 presents in several isoforms and its expression is dynamic and can serve as a companion marker for patients’ eligibility, allowing the identification of positive tumors that are more likely to respond to ICB therapy. The high PD-L1 expression in bladder-urothelial-carcinoma and squamous-cell carcinoma may affect further ICB-therapy application and outcomes. In general, divergent histologies are ineligible for therapy. These treatments are expensive and prone to auto-immune side effects and resistance. Thus, biomarkers capable of predicting therapy response are needed. Also, the PD-L1 expression assessment still needs refinement. Studies focused on squamous cell differentiation associated with S. haematobium remain scarce. Furthermore, in low and middle-income-regions, where schistosomiasis is endemic, SCC biomarkers are needed. This mini-review provides an overview of the current literature regarding PD-L1 expression in bladder-squamous-cell-carcinoma and schistosomiasis. It aims to pinpoint future directions, controversies, challenges, and the importance of PD-L1 as a biomarker for diagnosis, disease aggressiveness, and ICB-therapy prognosis in bladder-schistosomal-squamous-cell carcinoma.

HOXA11-AS1 Promotes PD-L1-Mediated Immune Escape and Metastasis of Hypopharyngeal Carcinoma by Facilitating PTBP1 and FOSL1 Association

Simple Summary

The metastasis of hypopharyngeal squamous cell carcinoma (HSCC) is the main reason for the poor prognosis of patients. Increasing studies have shown that abnormally expressed lncRNAs play crucial roles in HSCC, providing new perspectives for exploring cancer pathogenesis and matastasis. The expressions of HOXA11-AS1 and PD-L1 were found to be closely related to the overall survival of HSCC patients. Subsequently, the potential target genes, namely PBTP1 and FOSL1, were identified by expression correlation analysis. Finally, HOXA11-AS1/FOSL1/PTBP1/PD-L1 axis was identified to be a novel pathway provided a feasible preliminary basis for the future application of immunotherapy or targeted therapies in HSCC.

Abstract

Background: The metastatic characteristics of hypopharyngeal squamous cell carcinoma (HSCC) lead to many diagnostic and therapeutic challenges, while functional long non-coding RNAs (lncRNAs) can provide effective strategies for its diagnosis and treatment. Methods: RT-qPCR, Western blot, immunohistochemistry, and an immunofluorescence assay were used to detect the related gene expression. Flow cytometry was used to measure the percentage of CD8⁺ and CD4⁺ T cells. CCK-8 and transwell assays were performed to analyze the role of HOXA11-AS1. The targeted relationship of the FOSL1/PD-L1 promoter was measured by ChIP and dual-luciferase reporter assays. RNA pulldown and RIP assays were used to measure the interaction between HOXA11-AS1, FOSL1, and PTBP1. A tumor xenograft study was used to analyze HOXA11-AS1 function in vivo. Results: HOXA11-AS1, PD-L1, and FOSL1 were upregulated in HSCC, and HOXA11-AS1 positively correlated with PD-L1. HOXA11-AS1 knockdown upregulated CD8⁺ T cells through an increase in IFN-γ concentration while decreasing the proliferation, migration, and invasion of HSCC cells. FOSL1 bound the PD-L1 promoter, increasing gene expression. HOXA11-AS1 enhanced the stability of FOSL1 mRNA by binding to PTBP1. HOXA11-AS1 or PTBP1 overexpression increased FOSL1 and PD-L1 expression. PD-L1 knockdown arrested the inhibiting function of HOXA11-AS1 overexpression on CD8⁺ T cell content. HOXA11-AS1 knockdown inhibited immune escape and metastasis through PD-L1 regulation by downregulating FOSL1 in vivo. Conclusion: HOXA11-AS1 promoted PD-L1 expression by upregulating FOSL1 levels through PTBP1, thereby facilitating immune escape, proliferation, and metastasis of HSCC cells.

PD-L1 Testing in Urothelial Carcinoma: Analysis of a Series of 1401 Cases Using Both the 22C3 and SP142 Assays

Immune checkpoint blockade (ICB) drugs are a novel, effective treatment for advanced urothelial carcinoma. Worldwide, several different ICB drugs are approved, each developed and clinically validated with a specific PD-L1 compound diagnostic assay. As a result, PD-L1 testing workflows in routine practice are complex: requiring multiple assays across two platforms, with each assay having a different method of interpretation. Our service tested 1,401 urothelial carcinoma cases for PD-L1 expression, using both the 22C3 PharmDx assay (required prior to Pembrolizumab therapy) and SP142 assay (required prior to Atezolizumab therapy). Of the 1,401 cases tested, 621 cases (44%) were tested with both the 22C3 PharmDx and SP142 assays, 492 cases (35%) with 22C3 PharmDx only, and 288 cases (21%) with SP142 only. Each assay was used and interpreted according to the manufacturer’s guidelines. The rate of positivity we observed was 26% with the 22C3 assay and 31% with the SP142 assay, similar to the pre-licensing studies for both drugs. The discrepancy observed between the assays was 11%, which reinforces the requirement for utilisation of the correct assay for each agent, and limits potential cross-utility of assays. This aspect must be considered when setting up a PD-L1 testing strategy in laboratories where both Pembrolizumab and Atezolizumab are available for the treatment of urothelial carcinoma but also has broader implications for testing of other cancers where multiple ICB drugs and their respective assays are approved.

Management of Patients with Metastatic Bladder Cancer in the Real-World Setting from the Multidisciplinary Team: Current Opinion of the SOGUG Multidisciplinary Working Group

Simple Summary

This report presents clinically relevant advances in the management of metastatic bladder cancer, which have been the focus of discussion of expert members of the Spanish Oncology Genitourinary (SOGUG) Multidisciplinary Working Group in the framework of the Genitourinary Alliance project (12GU) designed as a space for the integration of novel information in the care of bladder cancer patients. The present study is focused on different aspects regarding integration of immunotherapy especially in the patient unfit for platinum-based chemotherapy, PD-L1 assays and samples to be evaluated, role of imaging techniques in preoperative staging or re-staging, definition and treatment approach of oligometastatic disease, and rescue strategies in responders. Involvement of a dedicated multidisciplinary team in the care of patients with mBC is crucial to improve outcome.

Abstract

Based on the discussion of current state of research of relevant topics of metastatic bladder cancer (mBC) among a group of experts of a Spanish Oncology Genitourinary (SOGUG) Working Group, a set of recommendations were proposed to overcome the challenges posed by the management of mBC in clinical practice. First-line options in unfit patients for cisplatin are chemotherapy with carboplatin and immunotherapy in PD-L1 positive patients. FDG-PET/CT may be a useful imaging technique in the initial staging or re-staging. In patients with oligometastatic disease, it is important to consider not only the number of metastatic lesions, but also the tumor biology and the clinical course. The combination of stereotactic body radiotherapy and immunotherapy with anti-PD-L1 monoclonal antibodies is under investigation and could improve the results of systemic treatment in patient with oligometastatic disease. Rescue treatment with curative intent could be considered in patients with oligometastatic disease after complete response on FDG-PET/CT. Metastatic disease should be evaluated using the same imaging modality over the course of the disease from diagnosis until rescue treatment. For improving the outcome of patients with mBC, the involvement of a dedicated multidisciplinary team, including urologists, pathologists, oncologists, radiologists and other specialists is of outmost importance in the daily care of these patients.

Concordance between Three PD-L1 Immunohistochemical Assays in Head and Neck Squamous Cell Carcinoma (HNSCC) in a Multicenter Study

The introduction of immunotherapy targeting the programmed death-1 (PD-1)/programmed death-ligand-1 (PD-L1) axis has represented a turning point in the treatment of HNSCC. Harmonization studies comparing the different antibodies and immunohistochemistry platforms available for the evaluation of PD-L1 expression with Combined Positive Score (CPS) in HNSCC are strongly required. Tissue microarrays (TMA) constructed from formalin-fixed, paraffin-embedded (FFPE) tissue blocks of HNSCC tumor were stained with two commercial in-vitro diagnostic (IVD) PD-L1 immunohistochemical assays (22C3 pharmDx on Autostainer Link48 and Omnis platforms, and SP263) and were reviewed by seven trained pathologists to assess CPS. We found a very similar distribution for PD-L1 expression between 22C3 pharmDx assay with both platforms and SP263 assay and a strong significant correlation between the two assays in different platforms (p < 0.0001). The interobserver reliability among pathologists for the continuous scores of CPS with intraclass correlation coefficient (ICC) and the correlation between the two assays were both good. Moreover, the agreement rate between assays was high at all cut-offs, while the kappa values were from substantial to almost perfect. These data suggest the interchangeability of the two antibodies and of the different immunohistochemical platforms in the selection of patients with HNSCC for immunotherapy.

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.

Evaluation of programmed death ligand 1 expression in cytology to determine eligibility for immune checkpoint inhibitor therapy in patients with head and neck squamous cell carcinoma

BACKGROUND

Immune checkpoint inhibitors targeting the programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway have recently emerged as a frontline treatment for head and neck squamous cell carcinoma (HNSCC). The evaluation of PD-L1 expression by immunohistochemistry in histologic samples is used to determine the eligibility of patients with HNSCC for immunotherapy. Patients with newly diagnosed HNSCC are frequently diagnosed by fine-needle aspiration (FNA) of lymph nodes with metastatic disease. However, the evaluation of PD-L1 expression with the proposed combined positive score (CPS) has not been well established in cytology specimens.

METHODS

This study retrospectively identified 21 HNSCC patients with a known PD-L1 status from histologic specimens and matched FNA specimens with tumor cells on cell blocks (CBs). The CB sections were stained with a PD-L1 antibody (22C3 clone). All cases were scored with CPS and the tumor proportion score (TPS).

RESULTS

The data showed substantial concordance between cytologic and histologic specimens for CPS (agreement, 76.2%; κ = 0.607) and TPS (agreement, 76.2%; κ = 0.607). With histology used as a reference standard, the positive predictive value was 100% for both CPS and TPS, whereas the negative predictive value was 57.1% for CPS assessments and 50% for TPS assessments.

CONCLUSIONS

PD-L1 expression in HNSCC cytology samples has high concordance with paired histologic samples. PD-L1 CPS evaluation is feasible in HNSCC cytology CBs and can act as a surrogate for determining eligibility for immunotherapy in cases in which a histologic specimen is not readily available.

Programmed death ligand-1 (PD-L1) immunohistochemical assessment using the QR1 clone in muscle-invasive urothelial carcinomas: a comparison with reference clones 22C3 and SP263

Programmed death ligand-1 (PD-L1) immunohistochemical (IHC) status is used to predict which patients with metastatic urothelial carcinoma (UC) will respond to immunotherapy. We aimed to compare QR1(Quartett), 22C3 (Dako), and SP263 (Ventana) detection of PD-L1 expression in muscle-invasive UCs and determine the best scoring algorithm for assessment of PD-L1 expression when using the QR1 clone. Our study included 69 UCs. For SP263 and 22C3, PD-L1-positive tumor cell (TC) and/or immune cell (IC) percentages (TC%/IC%) and the Combined Positive Score (CPS) were assessed, respectively (positivity cut-offs of ≥ 25% and ≥ 10). For QR1, both interpretation systems were evaluated. The concordances between assays were calculated. PD-L1 IHC staining characteristics were comparable between QR1, 22C3, and SP263 in both conventional and variant histology UCs. We demonstrated strong or very strong correlations between clones; the strongest correlation for TCs was between QR1 and SP263 (r = 0.92; p = 0.001) and for ICs was between QR1 and 22C3 (r = 0.85; p = 0.001). Our comparative analysis of the scoring algorithms revealed very good concordances among the three assays (range 0.791-0.878); the highest concordance was between QR1 and SP263 when CPS was used as the scoring algorithm for QR1 (0.878; p < 0.001). Our study is the first to demonstrate that the QR1 clone can be used to evaluate PD-L1 status in UCs, with a very good agreement rate with the reference clones. QR1 appeared to be more similar to the SP263 clone. With regard to the scoring algorithm, when evaluating PD-L1 expression using QR1 clone, CPS performed better compared with the TC%/IC% score.

Differences in genomic profile of high-grade urothelial carcinoma according to tumor location

OBJECTIVES

To establish targeted therapies based on the molecular landscape in upper urinary tract urothelial carcinoma (UTUC), we tried to investigate the molecular characteristics of UTUC compared with those of bladder urothelial carcinoma (BLUC) by next-generation sequencing (NGS).

MATERIALS AND METHODS

We selected 71 high-grade infiltrating urothelial carcinoma tissue specimens from 33 UTUC and 38 BLUC patients. NGS analysis was performed with the Illumina TruShigt Oncology-500 panel.

RESULTS

Both UTUC and BLUC showed similar clinicopathologic characteristics, as well as morphologic similarities. The median tumor mutation burden (TMB) of all cases was 7.8 mutations/Mb. The majority of alterations were missense mutations. TP53 (40/71, 56.3%), KDM6A (30/71, 42.3%), and TERT promoter mutations (23/71, 32.4%) were observed regardless of tumor location. Compared with UTUC, BLUC showed frequent mutations in several genes: ARID1A (P = 0.001), ASXL1 (P = 0.017), ERBB3 (P = 0.005), PRKDC (P = 0.004) and RB1 (P = 0.041). On the contrary, copy number loss of FGFR3 was observed more in UTUC than BLUC (P = 0.018). Also, 6 cases showed oncogenic fusions: 3 cases with FGFR2 fusion in UTUC and 3 cases with FGFR3-TACC3 fusion in BLUC.

CONCLUSION

Despite the small cohort size, we identified genetic differences between UTUC and BLUC in Korean patients by NGS. An understanding of the comprehensive molecular characteristics of UTUC and BLUC may be helpful in detecting candidates for targeted therapy.

Targeting PD-L1 (Programmed death-ligand 1) and inhibiting the expression of IGF2BP2 (Insulin-like growth factor 2 mRNA-binding protein 2) affect the proliferation and apoptosis of hypopharyngeal carcinoma cells

Programmed cell death-ligand 1 (PD-L1) have been attracting increasing attention in cancer diagnosis and treatment. The insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) is involved in the progression of multiple types of cancer. So, the role of IGF2BP2 and PD-L1 in hypopharyngeal carcinoma was assessed. Western blotting and immunochemistry were used to evaluate the expression of IGF2BP2 and PD-1/PD-L1. IGF2BP2 expression was knocked down in FaDu cells, and the effects on cell viability, apoptosis and proliferation were measured. A tumor-bearing nude model of hypopharyngeal carcinoma was constructed to evaluate the effect of a PD-L1 inhibitor and IGF2BP2 knockdown on hypopharyngeal carcinoma in vivo. RNA pull-down assays were used to assess the interaction between IGF2BP2 and PD-L1. The results showed that knockdown of IGF2BP2 inhibited FaDu cell proliferation and promoted apoptosis, as evidenced by the lower cell viability, a higher ratio of TUNEL-positive cells, decreased expression of Bcl-2 and cyclins, and increased expression of cleaved-caspase 3. In vivo, the tumor volume and weight were reduced by both the PD-L1 inhibitor and IGF2BP2 knockdown. Additionally, the interaction between PD-L1 and IGF2BP2 was confirmed. In conclusion, the results in the present study revealed that inhibition of IGF2BP2 might be a potentially relevant method for treating hypopharyngeal carcinoma, and the effects might be mediated via inhibition of the PD-1/PD-L1 axis.

PD-L1 evaluation in head and neck squamous cell carcinoma: Insights regarding specimens, heterogeneity and therapy

Immunohistochemical assessment with combined positive score (CPS) of programmed death-ligand 1 (PD-L1) is the prerequisite for administration of checkpoint inhibitor therapy in head and neck squamous cell carcinoma (HNSCC). Practicing pathologists are required to assess PD-L1 in routinary work and can be faced up with practical issues not always addressed in clinical trials or guidelines, such as choice of specimen to test, the intrinsic heterogeneity in PD-L1 expression in tumors and the potential impact of already administered therapy, given that patients' material can be procured at several times of cancer natural history. In the present work, we review and discuss the recent literature regarding the assessment of PD-L1 in HNSCC from the perspective of the practicing pathologist, providing some evidence on the single issues. It emerges a general trend to an underestimation of PD-L1 expression in biopsies compared to resection specimens and to a higher degree of positivity in metastatic lymph nodes in respect to primary tumors. Moreover, therapy shows to have contrasting effect on PD-L1 expression. Although further studies are needed, taking into account the intrinsic heterogeneity in PD-L1 expression and the conflicting evidences, it may be speculated that the most recent material of patients in respect to the natural history of tumor can be the most reliable to evaluate PD-L1 expression.

Evaluating programmed death-ligand 1 (PD-L1) in head and neck squamous cell carcinoma: concordance between the 22C3 PharmDx assay and the SP263 assay on whole sections from a multicentre study

AIMS

The introduction of immunotherapy for patients with head and neck squamous cell carcinoma (HNSCC) raises the need for harmonisation between different types of antibody and immunohistochemistry platform for evaluating the expression of PD-L1 by use of the combined positive score (CPS) in this tumour. The aim of this study was to compare the expression of PD-L1 as determined with the CPS and two widely used assays (the 22C3 PharmDx assay and the SP263 assay) in a cohort of HNSCCs.

METHODS AND RESULTS

We analysed 43 whole sections of HNSCC with two different anti-PD-L1 antibodies, 22C3 and SP263. The results, expressed as the CPS, were evaluated by 10 trained pathologists and statistical analyses were performed. We found a very similar results for PD-L1 expression between the 22C3 PharmDx assay and the SP263 assay in our cohort, and a strong and significant correlation between the two assays for all specimens (P < 0.0001). The interobserver reliability among pathologists for the continuous scores of CPS with the intraclass correlation coefficient and the correlation between the two assays were both good. Moreover, the rate of agreement between assays was high at all cut-offs and was best for the most relevant cut-off of CPS ≥ 1, and the kappa values were always in the range of almost perfect.

CONCLUSIONS

Two different assays (the 22C3 PharmDx assay and SP263 assay) for PD-L1 in HNSCC showed high agreement. These data suggest that these two assays are interchangeable in the selection of patients with HNSCC for immunotherapy.

Automated PD-L1 Scoring Using Artificial Intelligence in Head and Neck Squamous Cell Carcinoma

Immune checkpoint inhibitors (ICI) represent a new therapeutic approach in recurrent and metastatic head and neck squamous cell carcinoma (HNSCC). The patient selection for the PD-1/PD-L1 inhibitor therapy is based on the degree of PD-L1 expression in immunohistochemistry reflected by manually determined PD-L1 scores. However, manual scoring shows variability between different investigators and is influenced by cognitive and visual traps and could therefore negatively influence treatment decisions. Automated PD-L1 scoring could facilitate reliable and reproducible results. Our novel approach uses three neural networks sequentially applied for fully automated PD-L1 scoring of all three established PD-L1 scores: tumor proportion score (TPS), combined positive score (CPS) and tumor-infiltrating immune cell score (ICS). Our approach was validated using WSIs of HNSCC cases and compared with manual PD-L1 scoring by human investigators. The inter-rater correlation (ICC) between human and machine was very similar to the human-human correlation. The ICC was slightly higher between human-machine compared to human-human for the CPS and ICS, but a slightly lower for the TPS. Our study provides deeper insights into automated PD-L1 scoring by neural networks and its limitations. This may serve as a basis to improve ICI patient selection in the future.

SP142 PD-L1 Scoring Shows High Interobserver and Intraobserver Agreement in Triple-negative Breast Carcinoma But Overall Low Percentage Agreement With Other PD-L1 Clones SP263 and 22C3

SP142 programmed cell death ligand 1 (PD-L1) status predicts response to atezolizumab in triple-negative breast carcinoma (TNBC). Prevalence of VENTANA PD-L1 (SP142) Assay positivity, concordance with the VENTANA PD-L1 (SP263) Assay and Dako PD-L1 IHC 22C3 pharmDx assay, and association with clinicopathologic features were assessed in 447 TNBCs. SP142 PD-L1 intraobserver and interobserver agreement was investigated in a subset of 60 TNBCs, with scores enriched around the 1% cutoff. The effect of a 1-hour training video on pretraining and posttraining scores was ascertained. At a 1% cutoff, 34.2% of tumors were SP142 PD-L1 positive. SP142 PD-L1 positivity was significantly associated with tumor-infiltrating lymphocytes (P <0.01), and node negativity (P=0.02), but not with tumor grade (P=0.35), tumor size (P=0.58), or BRCA mutation (P=0.53). Overall percentage agreement (OPA) for intraobserver and interobserver agreement was 95.0% and 93.7%, respectively, among 5 pathologists trained in TNBC SP142 PD-L1 scoring. In 5 TNBC SP142 PD-L1-naive pathologists, significantly higher OPA to the reference score was achieved after video training (posttraining OPA 85.7%, pretraining OPA 81.5%, P<0.05). PD-L1 status at a 1% cutoff was assessed by SP142 and SP263 in 420 cases, and by SP142 and 22C3 in 423 cases, with OPA of 88.1% and 85.8%, respectively. The VENTANA PD-L1 (SP142) Assay is reproducible for classifying TNBC PD-L1 status by trained observers; however, it is not analytically equivalent to the VENTANA PD-L1 (SP263) Assay and Dako PD-L1 IHC 22C3 pharmDx assay.

PD-L1 Expression Harmonization in Gastric Cancer Using 22C3 PharmDx and SP263 Assays

The immune checkpoint inhibitor Pembrolizumab has been FDA-approved for the treatment of gastric cancer (GC) and gastroesophageal junction (GEJ) cancer in patients who fail second-line therapy and test positive by a companion programed death ligand 1 (PD-L1) assay, the 22C3 PharmDx. It would be useful to investigate the potential interchangeability of other PD-L1 assays in order to develop a more sustainable diagnostic strategy. We investigated the possibility of harmonizing different PD-L1 assays, utilizing samples from 94 GC and GEJ patients to compare their expression using 2 laboratory developed tests (LDTs): The Dako 22C3 antibody and the Ventana SP263 run on the Ventana platform with the FDA-approved companion diagnostic test, the 22C3 PharmDx. This would be the first report assessing the 22C3 on Ventana's platform in GC. Pearson correlation coefficients between the Dako 22C3 PharmDx and the 22C3-LDT and the Ventana SP263 assays were 0.965 (P<0.001) and 0.932 (P<0.001), respectively, which indicates an almost perfect correlation. The sensitivity and specificity were also high at different cutoffs [both 100% at combined positive score (CPS)≥1 and 92.59% and 95.52% at CPS≥10, respectively] for the comparison between Dako 22C3/22C3-LDT assays. As for the sensitivity and specificity between the Dako 22C3/Ventana SP263 assays the results were 100% and 95.67% at CPS≥1; and 96.30% and 95.52% at CPS≥10, respectively. In conclusion, the analytical performance of 22C3 and SP263 clones on the Ventana platform was close to that of the reference assay (Dako 22C3 assay), suggesting that the 2 LDTs can be utilized interchangeably with the FDA-approved standard assay as an aid to select GC and GEJ patients for Pembrolizumab treatment.

Challenges facing pathologists evaluating PD-L1 in head & neck squamous cell carcinoma

BACKGROUND

Programmed death-ligand 1 (PD-L1) expression with combined positive score (CPS) ≥1 is required for administration of checkpoint inhibitor therapy in recurrent/metastatic head and neck squamous cell carcinoma (HNSCC). The 22C3 pharmDx Dako immunohistochemical assay is the one approved as companion diagnostic for pembrolizumab, but many laboratories work on other platforms and/or with other clones, and studies exploring the potential interchangeability of assays have appeared.

EVIDENCE FROM THE LITERATURE

After review of the literature, it emerges that the concordance among assays ranges from fair to moderate, with a tendence of assay SP263 to yield a higher quota of positivity and of assay SP142 to stain better immune cells. Moreover, pathologists achieve very good concordance in assessing PD-L1 CPS, particularly with SP263.

CONCLUSIONS

Differences in terms of platforms, procedures, and study design still preclude a quantitative synthesis of evidence and clearly further work is needed to draw stronger conclusions on the interchangeability of PD-L1 assays in HNSCC.

Automated tumor proportion scoring for PD-L1 expression based on multistage ensemble strategy in non-small cell lung cancer

Introduction

Programmed cell death ligand-1 (PD-L1) expression is a promising biomarker for identifying treatment related to non-small cell lung cancer (NSCLC). Automated image analysis served as an aided PD-L1 scoring tool for pathologists to reduce inter- and intrareader variability. We developed a novel automated tumor proportion scoring (TPS) algorithm, and evaluated the concordance of this image analysis algorithm with pathologist scores.

Methods

We included 230 NSCLC samples prepared and stained using the PD-L1(SP263) and PD-L1(22C3) antibodies separately. The scoring algorithm was based on regional segmentation and cellular detection. We used 30 PD-L1(SP263) slides for algorithm training and validation.

Results

Overall, 192 SP263 samples and 117 22C3 samples were amenable to image analysis scoring. Automated image analysis and pathologist scores were highly concordant [intraclass correlation coefficient (ICC) = 0.873 and 0.737]. Concordances at moderate and high cutoff values were better than at low cutoff values significantly. For SP263 and 22C3, the concordances in squamous cell carcinomas were better than adenocarcinomas (SP263 ICC = 0.884 vs 0.783; 22C3 ICC = 0.782 vs 0.500). In addition, our automated immune cell proportion scoring (IPS) scores achieved high positive correlation with the pathologists TPS scores.

Conclusions

The novel automated image analysis scoring algorithm permitted quantitative comparison with existing PD-L1 diagnostic assays and demonstrated effectiveness by combining cellular and regional information for image algorithm training. Meanwhile, the fact that concordances vary in different subtypes of NSCLC samples, which should be considered in algorithm development.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02898-z.

Comparison of three PD-L1 immunohistochemical assays in head and neck squamous cell carcinoma (HNSCC)

Expression of programmed cell death-ligand 1 (PD-L1) is being used as predictive biomarker for immunotherapy in head and neck squamous cell carcinoma (HNSCC). Several antibodies are available for PD-L1 testing and multiple staining and scoring methods are used. This study aimed to compare the performance of two PD-L1 standardized assays (SP263 and 22C3 pharmDx) and one laboratory-developed test (LDT) (22C3) in HNSCC using the tumor proportion score (TPS) and the combined positive score (CPS). Pretreatment biopsies from 147 HNSCC patients were collected in a tissue-microarray (TMA). Serial sections of the TMA were immunohistochemically stained for PD-L1 expression using 22C3 pharmDx on the Dako Link 48 platform, SP263 on the Ventana Benchmark Ultra platform, and 22C3 as an LDT on the Ventana Benchmark Ultra. Stained slides were assessed for TPS and CPS. Cutoffs of ≥1% and ≥50% for TPS and ≥1 and ≥20 for CPS were used. Concordance between the different staining assays was moderate to poor for TPS (intraclass correlation coefficient (ICC) 0.46) as well as for CPS (ICC 0.34). When stratifying patients by clinically relevant cutoffs, considerable differences between the assays were observed: concordance was poor for both TPS and CPS. Generally, SP263 stained a higher percentage of cells than the other assays, especially when using the CPS. Moderate concordance was shown between three different PD-L1 immunohistochemical assays and considerable differences in PD-L1 positivity were observed when using clinically relevant cutoffs. This should be taken into account when using PD-L1 expression to guide clinical practice.

[Predictive diagnostics for checkpoint inhibitors]

Checkpoint inhibitors have revolutionized oncological treatment in many cancers and added a new immuno-oncological treatment pillar to the medicinal arsenal of conventional and molecularly targeted therapies. In monotherapy and in combination therapies, however, not all patients respond equally well, even in generally responsive tumor entities. Therefore, since the introduction of these therapies, a major focus has been the research on and implementation of predictive markers for patient selection. The first established biomarker, the expression of the target molecule PD-L1, has found its way into routine diagnostics in a large number of unfortunately very divergent diagnostic constellations in multiple entities. In addition, some molecular predictors, including the measurement of microsatellite instability and tumor mutational burden, have also been suggested and in some cases are already implemented into routine diagnostics. Additional molecular parameters have been proposed but most of them have not yet found their way into routine patient care. This review article discusses the current status and recent developments in the field of diagnostic response predictors in the context of an immune checkpoint blockade.

PD-L1 expression in urothelial bladder cancer varies more among specimen types than between companion assays

Urothelial bladder cancer (UBC) patients ineligible to platinum-based chemotherapy can be treated with immune-checkpoint inhibitors (ICI) in Programmed Death Ligand 1 (PD-L1) positive cases. Although concordance exists between different PD-L1 assays, little is known on PD-L1 expression variability in matched UBC samples. We compared PD-L1 expression in whole slides of matched transurethral resections (TURBT), radical cystectomies (RC), and lymph node metastasis (LN). Immunohistochemistry using the VENTANA PD-L1 (SP263) assay was performed on 115 patients and scored positive if expression occurred in ≥25% immune cells (IC), ≥25% tumour cells (TC), or both. PD-L1 was positive in 42.7% TURBT, 39.8% RC, and 27.3% LN specimens. Concordance was moderate (κ=0.52; P<0.001) between TURBT and RC, and fair between LN and TURBT (κ=0.31; P=0.048) or RC (κ=0.25; P=0.075). Comparison with the VENTANA PD-L1 (SP142) assay which had been performed previously on the same cohort showed moderate to substantial inter-assay agreement (κ=0.42-0.66). Although TC staining is not part of the SP142 scoring algorithm, discordant PD-L1 assay outcome could be attributed to SP263 TC≥25% staining in only 41% of cases. These results show that PD-L1 expression variability between matched specimens is higher than that between individual assays. Optimal specimen determination for PD-L1 testing needs to be addressed in future studies.

Programmed cell death-ligand 1 assessment in urothelial carcinoma: prospect and limitation

Programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) inhibition has revolutionized the treatment paradigm of urothelial carcinoma (UC). Several PD-L1 assays are conducted to formulate appropriate treatment decisions for PD-1/PD-L1 target therapy in UC. However, each assay has its own specific requirement of antibody clones, staining platforms, scoring algorithms, and cutoffs for the determination of PD-L1 status. These prove to be challenging constraints to pathology laboratories and pathologists. Thus, the present article comprehensively demonstrates the scoring algorithm used and differences observed in each assay (22C3, SP142, and SP263). Interestingly, the SP142 score algorithm considers only immune cells and not tumor cells (TCs). It remains controversial whether SP142 expressed only in TCs truly accounts for a negative PD-L1 case. Moreover, the scoring algorithm of each assay is complex and divergent, which can result in inter-observer heterogeneity. In this regard, the development of artificial intelligence for providing assistance to pathologists in obtaining more accurate and objective results has been actively researched. To facilitate efficiency of PD-L1 testing, several previous studies attempted to integrate and harmonize each assay in UC. The performance comparison of the various PD-L1 assays demonstrated in previous studies was encouraging, the exceptional concordance rate reported between 22C3 and SP263. Although these two assays may be used interchangeably, a clinically validated algorithm for each agent must be applied.

Prognostic value of PD-L1 combined positive score in patients with upper tract urothelial carcinoma

PURPOSE

Upper tract urothelial carcinoma (UTUC) is relatively rare in Western countries. The impact of programmed death-ligand 1 (PD-L1) expression on UTUC remains unclear because previous studies have focused on bladder UC. We investigated the association of PD-L1 expression with clinicopathological features and prognosis in patients with UTUC.

METHODS

We retrospectively reviewed the patients with UTUC that we treated at our institute from 2013 to 2018. In total, 105 patients with UTUC undergoing radical nephroureterectomy were analyzed to evaluate the PD-L1 expression on representative whole-tissue sections using the Combined Positive Score (CPS; Dako 22C3 pharmDx assay). A PD-L1 CPS ≥ 10 was considered positive.

RESULTS

Among the 105 UTUC cases, 17.1% exhibited positive PD-L1 expression. A CPS ≥ 10 was significantly associated with higher tumor stage (≥ T2, p = 0.034) and lymph node invasion at diagnosis (p = 0.021). A multivariable analysis indicated that a CPS ≥ 10 was an independent prognostic predictor of shorter cancer-specific survival (hazard ratio [HR] = 4.59, 95% confidence interval [CI] = 1.66 - 12.7, p = 0.003) and overall survival (HR = 2.51, 95% CI = 1.19 - 5.27, p = 0.015).

CONCLUSIONS

A PD-L1 CPS ≥ 10 in UTUC was associated with adverse pathological features and independently predicted worse cancer-specific and overall survival.

Interpretation According to Clone-Specific PD-L1 Cutoffs Reveals Better Concordance in Muscle-Invasive Urothelial Carcinoma

Because immune checkpoint inhibitors have been approved for treating advanced urothelial carcinoma (UC), programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) assays have been widely used as companion or complementary diagnostic tests for predicting treatment outcomes. Because different clones, scoring algorithms, and cutoffs have been used for interpretation, this study investigated the variation, correlation, and concordance of four validated PD-L1 clones (SP142, SP263, 22C3, and 28-8) and proposed a practical solution for the harmonization of PD-L1 IHC. A tissue microarray, including 46 muscle-invasive UCs, was constructed for PD-L1 testing with the four clones. Tumor cell (TC) and immune cell (IC) expression was analyzed. SP142 had significantly low TC expression, whereas SP263, 22C3, and 28-8 exhibited a moderate correlation (rho ≥ 0.6), with almost perfect concordance (intraclass correlation coefficient > 0.8) in TC expression. Fair to moderate correlation and concordance were observed in IC expression in most pairwise comparisons of clones. Substantial concordance (kappa > 0.6) was noted when high PD-L1 expression was defined by applying clone-specific cutoffs to each clone. Our findings imply that a universal cutoff value is not feasible for UC; we propose that PD-L1 IHC assays for UC should be interpreted according to a clone-specific scoring algorithm and cutoff value.

A multicentre analytical comparison study of inter-reader and inter-assay agreement of four programmed death-ligand 1 immunohistochemistry assays for scoring in triple-negative breast cancer

AIMS

Studies in various cancer types have demonstrated discordance between results from different programmed death-ligand 1 (PD-L1) assays. Here, we compare the reproducibility and analytical concordance of four clinically developed assays for assessing PD-L1-positivity in tumour-infiltrating immune cells in the tumour area (PD-L1-IC-positivity) in triple-negative breast cancer (TNBC).

METHODS AND RESULTS

Primary TNBC resection specimens (n = 30) were selected based on their PD-L1-IC-positivity per VENTANA SP142 (<1%: 15 cases; 1-5%: seven cases; >5%: eight cases). Serial histological sections were stained for PD-L1 using VENTANA SP142, VENTANA SP263, DAKO 22C3 and DAKO 28-8. PD-L1-IC-positivity and tumour cell expression (≥1 versus <1%) were scored by trained readers from seven sites using online virtual microscopy. The adjusted mean of PD-L1-IC-positivity for SP263 (7.8%) was significantly higher than those for the other three assays (3.7-4.9%). Differences in adjusted means were statistically significant between SP263 and the other three assays (P < 0.0001) but not between the three remaining assays when excluding SP263 (P = 0.0961-0.6522). Intra-class correlation coefficients revealed moderate-to-strong inter-reader agreement for each assay (0.460-0.805) and poor-to-strong inter-assay agreement for each reader (0.298-0.678) on PD-L1-IC-positivity.

CONCLUSIONS

In this first multicentre study of different PD-L1 assays in TNBC, we show that PD-L1-IC-positivity for SP142, 22C3 and 28-8 was reproducible and analytically concordant, indicating that these three assays may be analytically interchangeable. The relevance of the higher PD-L1-IC-positivity for SP263 should be further investigated.

PD-L1 Testing for Urothelial Carcinoma: Interchangeability, Reliability and Future Perspectives

Five programmed death-1/programmed death-ligand 1 (PD-L1) inhibitors are currently approved for the treatment of locally advanced or metastatic urothelial carcinoma of the bladder and the upper urinary tract. Following the FDA and EMA restrictions of first-line treatment with Atezolizumab and Pembrolizumab in platinum-ineligible patients, immunohistochemical PD-L1 testing is now required. Several emerging issues on antibodies, test platforms and scoring algorithms have raised concerns about the comparability and interchangeability between these assays. In this review, we have focused on the interchangeability of the used algorithms and assays for PD-L1 testing in urothelial carcinoma, on the predictive reliability of PD-L1 testing in urothelial carcinoma and the potential of other new and upcoming biomarkers.

Expression of Programmed Cell Death Ligand 1 as a Predictive Biomarker in Metastatic Urothelial Carcinoma Patients Treated with First-line Immune Checkpoint Inhibitors Versus Chemotherapy: A Systematic Review and Meta-analysis

CONTEXT

Immune checkpoint inhibitors (ICIs) have reported durable responses in selected groups of patients with metastatic urothelial carcinoma (mUC). However, identification of biomarkers predictive of response to ICIs remains an unmet need in mUC management, and the role of programmed cell death ligand 1 (PD-L1) expression remains controversial.

OBJECTIVE

In this systematic review and meta-analysis, we aimed at assessing the predictive value of PD-L1 in mUC patients receiving first-line ICIs as monotherapy or in combination with other anticancer agents across randomized controlled clinical trials (RCTs).

EVIDENCE ACQUISITION

We retrieved all the relevant RCTs through PubMed/Medline, Cochrane library, and EMBASE; proceedings of the main international oncological meetings were also searched for relevant abstracts. Eligible studies included RCTs evaluating ICIs versus chemotherapy in PD-L1-positive mUCs; the primary endpoint was overall survival (OS).

EVIDENCE SYNTHESIS

Three phase III trials matched our eligibility criteria; a total of 2237 PD-L1-positive mUC patients (ICIs: 1125; chemotherapy: 1112) were included in the analysis. Compared with chemotherapy, ICIs were associated with higher OS in PD-L1-positive patients (hazard ratio [HR] 0.86, 95% confidence interval [CI] 0.78-0.96; p = 0.007); conversely, no differences were observed in the PD-L1-negative patient population (HR 1.03, 95% CI 0.89-1.19; p < 0.001).

CONCLUSIONS

Compared with standard chemotherapy, our results suggested a survival benefit in PD-L1-positive mUC patients receiving ICIs; conversely, no benefit was observed in patients with PD-L1-negative disease. Although this systematic review and meta-analysis should be interpreted with caution due to several issues, our results highlight the need for reliable predictive biomarkers of response to ICIs, providing a benchmark for future studies in this setting.

PATIENT SUMMARY

Despite immune checkpoint inhibitors (ICIs) having revolutionized the treatment landscape of metastatic urothelial carcinoma (mUC), an important percentage of patients do not experience clinical benefit or durable responses. Identification of reliable biomarkers of response to ICIs remains a mandatory need in mUC management, and further efforts are needed to standardize the assessment of programmed cell death ligand 1 in urothelial carcinoma.

Multiplex immunofluorescence to measure dynamic changes in tumor-infiltrating lymphocytes and PD-L1 in early-stage breast cancer

BACKGROUND

The H&E stromal tumor-infiltrating lymphocyte (sTIL) score and programmed death ligand 1 (PD-L1) SP142 immunohistochemistry assay are prognostic and predictive in early-stage breast cancer, but are operator-dependent and may have insufficient precision to characterize dynamic changes in sTILs/PD-L1 in the context of clinical research. We illustrate how multiplex immunofluorescence (mIF) combined with statistical modeling can be used to precisely estimate dynamic changes in sTIL score, PD-L1 expression, and other immune variables from a single paraffin-embedded slide, thus enabling comprehensive characterization of activity of novel immunotherapy agents.

METHODS

Serial tissue was obtained from a recent clinical trial evaluating loco-regional cytokine delivery as a strategy to promote immune cell infiltration and activation in breast tumors. Pre-treatment biopsies and post-treatment tumor resections were analyzed by mIF (PerkinElmer Vectra) using an antibody panel that characterized tumor cells (cytokeratin-positive), immune cells (CD3, CD8, CD163, FoxP3), and PD-L1 expression. mIF estimates of sTIL score and PD-L1 expression were compared to the H&E/SP142 clinical assays. Hierarchical linear modeling was utilized to compare pre- and post-treatment immune cell expression, account for correlation of time-dependent measurement, variation across high-powered magnification views within each subject, and variation between subjects. Simulation methods (Monte Carlo, bootstrapping) were used to evaluate the impact of model and tissue sample size on statistical power.

RESULTS

mIF estimates of sTIL and PD-L1 expression were strongly correlated with their respective clinical assays (p < .001). Hierarchical linear modeling resulted in more precise estimates of treatment-related increases in sTIL, PD-L1, and other metrics such as CD8+ tumor nest infiltration. Statistical precision was dependent on adequate tissue sampling, with at least 15 high-powered fields recommended per specimen. Compared to conventional t-testing of means, hierarchical linear modeling was associated with substantial reductions in enrollment size required (n = 25➔n = 13) to detect the observed increases in sTIL/PD-L1.

CONCLUSION

mIF is useful for quantifying treatment-related dynamic changes in sTILs/PD-L1 and is concordant with clinical assays, but with greater precision. Hierarchical linear modeling can mitigate the effects of intratumoral heterogeneity on immune cell count estimations, allowing for more efficient detection of treatment-related pharmocodynamic effects in the context of clinical trials.

TRIAL REGISTRATION

NCT02950259 .

Immune Checkpoint Inhibitors for the Treatment of Bladder Cancer

A number of immune checkpoint inhibitors (ICIs) have been approved as first-line therapy in case of cisplatin-ineligible patients or as second-line therapy for patients with metastatic urothelial carcinoma (mUC) of the bladder. About 30% of patients with mUC will respond to ICIs immunotherapy. Programmed death-ligand 1 (PD-L1) expression detected by immunohistochemistry seems to predict response to immune checkpoint inhibitors in patients with mUC as supported by the objective response rate (ORR) and overall survival (OS) associated with the response observed in most clinical trials. Pembrolizumab, an anti-PD-1 antibody, demonstrated better OS respective to chemotherapy in a randomized phase 3 study for second-line treatment of mUC. Nivolumab, a PD-1 antibody, also demonstrated an OS benefit when compared to controls. Atezolizumab, Durvalumab, and Avelumab antibodies targeting PD-L1 have also received approval as second-line treatments for mUC with durable response for more than 1 year in selected patients. Atezolizumab and Pembrolizumab also received approval for first-line treatment of patients that are ineligible for cisplatin. A focus on the utility of ICIs in the adjuvant or neoadjuvant setting, or as combination with chemotherapy, is the basis of some ongoing trials. The identification of a clinically useful biomarker, single or in association, to determine the optimal ICIs treatment for patients with mUC is very much needed as emphasized by the current literature. In this review, we examined relevant clinical trial results with ICIs in patients with mUC alone or as part of drug combinations; emphasis is also placed on the adjuvant and neoadjuvant setting. The current landscape of selected biomarkers of response to ICIs including anti-PD-L1 immunohistochemistry is also briefly reviewed.

Programmed death ligand-1 (PD-L1) as a predictive marker for immunotherapy in solid tumours: a guide to immunohistochemistry implementation and interpretation

Immunotherapy with checkpoint inhibitors is well established as an effective treatment for non-small cell lung cancer and melanoma. The list of approved indications for treatment with PD-1/PD-L1 checkpoint inhibitors is growing rapidly as clinical trials continue to show their efficacy in patients with a wide range of solid tumours. Clinical trials have used a variety of PD-L1 immunohistochemical assays to evaluate PD-L1 expression on tumour cells, immune cells or both as a potential biomarker to predict response to immunotherapy. Requests to pathologists for PD-L1 testing to guide choice of therapy are rapidly becoming commonplace. Thus, pathologists need to be aware of the different PD-L1 assays, methods of evaluation in different tumour types and the impact of the results on therapeutic decisions. This review discusses the key practical issues relating to the implementation of PD-L1 testing for solid tumours in a pathology laboratory, including evidence for PD-L1 testing, different assay types, the potential interchangeability of PD-L1 antibody clones and staining platforms, scoring criteria for PD-L1, validation, quality assurance, and pitfalls in PD-L1 assessment. This review also explores PD-L1 IHC in solid tumours including non-small cell lung carcinoma, head and neck carcinoma, triple negative breast carcinoma, melanoma, renal cell carcinoma, urothelial carcinoma, gastric and gastroesophageal carcinoma, colorectal carcinoma, hepatocellular carcinoma, and endometrial carcinoma. The review aims to provide pathologists with a practical guide to the implementation and interpretation of PD-L1 testing by immunohistochemistry.

The impact of pre-analytical parameters on class II biomarkers by immunohistochemistry: concordance across four tissue processing protocols

In the modern era of precision medicine, a number of class II immunohistochemistry (IHC) biomarkers are routinely tested in pathologic laboratories to select cancer patients who may be candidates for hormonal, targeted, and immune therapies. Pre-analytical factors, including tissue processing, are critical components of biomarker testing and require validation to ensure reliable results. In this study, we aimed to study the impact of tissue processing on biomarkers (including ER, PR, HER2, mismatch repair (MMR) proteins, BRAF V600E, and PD-L1) in a large prospective cohort of 109 tumors. We found that ER and MMR were not impacted; PR, HER2, and BRAF V600E were minimally affected; and PD-L1 regardless of the antibody clone was strongly influenced by a combination of tissue processing procedures and intratumoral heterogeneity. Our findings suggest that validation of pre-analytical parameters, such as tissue processing, is important for certain class II biomarkers, in particular PD-L1 IHC.

PD-L1 testing in urothelial bladder cancer: essentials of clinical practice

PURPOSE

While immunotherapy has become an increasingly attractive strategy in patients with urothelial bladder cancer, the need for a biomarker to identify patients whose cancer is the most likely to respond has never been more crucial. This review systematically evaluates evidence regarding PD-L1 as a predictive biomarker of response to anti-PD(L)1 monoclonal antibodies in patients with urothelial bladder carcinoma, and discusses its current limits in routine clinical practice.

METHODS

We performed a critical review of PubMed/Medline according to the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) statement. Prospective clinical trials evaluating anti-PD(L)1 monoclonal antibodies in urothelial bladder carcinoma together with retrospective studies evaluating PD-L1 expression in patients with bladder cancer were included.

RESULTS

Evidence data related to PD-L1 as a predictive biomarker of response to immune checkpoint blockade monotherapy across clinical trials are detailed in this review. The different companion diagnostic assays, and the methods for PD-L1 scoring in urothelial bladder carcinoma are reported. Additionally, the issues related to the implementation of PD-L1 testing in clinical practice are discussed.

CONCLUSIONS

PD-(L)1 monoclonal antibodies atezolizumab and pembrolizumab are restricted to patients with PD-L1 positive status in the first-line setting in patients with advanced or metastatic urothelial bladder carcinoma who are ineligible to cisplatin-based chemotherapy. Importantly, the use of anti-PD(L)1 mAb in the other clinical settings is not based on PD-L1 status, but rather on patients' clinical characteristics. Further identification of biomarkers with high negative predictive value will also be of utmost importance to identify patients who may not respond to such immunotherapies.

Immune checkpoints and their inhibitors: Reappraisal of a novel diagnostic and therapeutic dimension in the urologic malignancies

Advances in molecular immunology have unveiled some of the complexity of the mechanisms regulating cellular immune responses and led to the successful targeting of immune checkpoints in attempts to enhance antitumor T cell responses. Surgery, chemotherapy, and radiation therapy have been the mainstay of treatment in urologic malignancies. Immune checkpoint molecules such as cytotoxic T-lymphocyte associated protein-4, programmed cell death protein-1, and programmed death-ligand 1 have been shown to play central roles in evading cancer immunity. Thus these molecules have been targeted by inhibitors for the management of cancers forming the basis of immunotherapy. Immunotherapy is now among the first line therapeutic options for metastatic renal cell carcinomas. In advanced bladder cancer, immunotherapy is the standard of care in the second line and the first line for cisplatin ineligible patients. There continues to be ongoing research to identify the role if any of immunotherapy in testicular, prostatic, and penile cancers. The ideal biomarker for response to immunotherapy is still elusive. Although programmed death-ligand 1 immunohistochemical testing has been widely used across the globe as a biomarker for immunotherapy, companion diagnostic tests have inherent issues with testing and reporting and cannot have universal applicability. Additional biomarkers including, tumor mutational burden, deficient mismatch repair, high microsatellite instability, and immune gene expression profiling are being evaluated in various clinical trials. This review appraises the data of immunotherapy in the management of urologic malignancies.

Report From the International Society of Urological Pathology (ISUP) Consultation Conference On Molecular Pathology Of Urogenital Cancers. II. Molecular Pathology of Bladder Cancer: Progress and Challenges

During the 2019 International Society of Urological Pathology Consultation Conference on Molecular Pathology of Urogenital Cancer, the Working Group on Bladder Cancer presented the current status and made recommendations on the diagnostic use of molecular pathology, incorporating a premeeting survey. Bladder cancers are biologically diverse and can be separated into "molecular subtypes," based on expression profiling. These subtypes associate with clinical behavior, histology, and molecular alterations, though their clinical utility has not been demonstrated at present and use in bladder cancer is not recommended. Mutations in the TERT promoter are present in the majority of bladder cancers, including the noninvasive stage of tumor evolution, but not in reactive conditions. Mutational analysis of the TERT promoter thus distinguishes histologically deceptive cancers from their benign mimics in some cases. A minority of pathologists employ this test. FGFR3 mutations are common in bladder cancer, and metastatic urothelial carcinoma (UC) with such mutations frequently responds to erdafitinib, an FGFR inhibitor. Testing for FGFR3 alterations is required before using this drug. Metastatic UC responds to immune-oncology (IO) agents in 20% of cases. These are approved as first and second-line treatments in metastatic UC. Several biological parameters associate with response to IO agents, including tumor mutational burden, molecular subtype, and infiltration by programmed death-ligand 1-positive lymphocytes, detected by immunohistochemistry. Programmed death-ligand 1 immunohistochemistry is mandatory before administering IO agents in the first-line setting. In conclusion, much has been learned about the biology of bladder cancer, and this understanding has improved the care of patients with the disease.