Multicentric analytical comparability study of programmed death-ligand 1 expression on tumor-infiltrating immune cells and tumor cells in urothelial bladder cancer using four clinically developed immunohistochemistry assays

[German expert consensus on programmed cell death ligand 1 (PD-L1) testing in perioperative systemic therapy of muscle invasive bladder cancer]

The risk of recurrence in patients with muscle invasive bladder cancer (MIBC) after radical cystectomy depends on the pathological tumor stage. In particular, patients with lymph node metastasis (pN+), locally advanced (≥pT3), or residual muscle invasive tumor despite neoadjuvant chemotherapy are at high risk. Currently, the importance of adjuvant therapy with immune checkpoint inhibitors is increasing in the context of perioperative systemic therapeutic concepts. The indication for the PD‑1 inhibitor nivolumab currently approved in the European Union requires testing of PD-L1 (programmed cell death ligand 1) protein expression by immunochemistry in tumor tissue. Focusing on MIBC patients at high risk of recurrence, new questions arise regarding the implementation and interpretation of PD-L1 testing. An interdisciplinary group of experts from Germany has discussed relevant issues from a clinicopathological point of view and developed practical recommendations to facilitate the implementation of validated and quality-assured PD-L1 testing for the approved indications in daily clinical practice.

An artificial intelligence-powered PD-L1 combined positive score (CPS) analyser in urothelial carcinoma alleviating interobserver and intersite variability

AIMS

Immune checkpoint inhibitors targeting programmed death-ligand 1 (PD-L1) have shown promising clinical outcomes in urothelial carcinoma (UC). The combined positive score (CPS) quantifies PD-L1 22C3 expression in UC, but it can vary between pathologists due to the consideration of both immune and tumour cell positivity.

METHODS AND RESULTS

An artificial intelligence (AI)-powered PD-L1 CPS analyser was developed using 1,275,907 cells and 6175.42 mm2 of tissue annotated by pathologists, extracted from 400 PD-L1 22C3-stained whole slide images of UC. We validated the AI model on 543 UC PD-L1 22C3 cases collected from three institutions. There were 446 cases (82.1%) where the CPS results (CPS ≥10 or <10) were in complete agreement between three pathologists, and 486 cases (89.5%) where the AI-powered CPS results matched the consensus of two or more pathologists. In the pathologist's assessment of the CPS, statistically significant differences were noted depending on the source hospital (P = 0.003). Three pathologists reevaluated discrepancy cases with AI-powered CPS results. After using the AI as a guide and revising, the complete agreement increased to 93.9%. The AI model contributed to improving the concordance between pathologists across various factors including hospital, specimen type, pathologic T stage, histologic subtypes, and dominant PD-L1-positive cell type. In the revised results, the evaluation discordance among slides from different hospitals was mitigated.

CONCLUSION

This study suggests that AI models can help pathologists to reduce discrepancies between pathologists in quantifying immunohistochemistry including PD-L1 22C3 CPS, especially when evaluating data from different institutions, such as in a telepathology setting.

Scoring PD-L1 Expression in Urothelial Carcinoma: An International Multi-Institutional Study on Comparison of Manual and Artificial Intelligence Measurement Model (AIM-PD-L1) Pathology Assessments

Assessing programmed death ligand 1 (PD-L1) expression on tumor cells (TCs) using Food and Drug Administration-approved, validated immunoassays can guide the use of immune checkpoint inhibitor (ICI) therapy in cancer treatment. However, substantial interobserver variability has been reported using these immunoassays. Artificial intelligence (AI) has the potential to accurately measure biomarker expression in tissue samples, but its reliability and comparability to standard manual scoring remain to be evaluated. This multinational study sought to compare the %TC scoring of PD-L1 expression in advanced urothelial carcinoma, assessed by either an AI Measurement Model (AIM-PD-L1) or expert pathologists. The concordance among pathologists and between pathologists and AIM-PD-L1 was determined. The positivity rate of ≥ 1%TC PD-L1 was between 20-30% for 8/10 pathologists, and the degree of agreement and scoring distribution for among pathologists and between pathologists and AIM-PD-L1 was similar both scored as a continuous variable or using the pre-defined cutoff. Numerically higher score variation was observed with the 22C3 assay than with the 28-8 assay. A 2-h training module on the 28-8 assay did not significantly impact manual assessment. Cases exhibiting significantly higher variability in the assessment of PD-L1 expression (mean absolute deviation > 10) were found to have patterns of PD-L1 staining that were more challenging to interpret. An improved understanding of sources of manual scoring variability can be applied to PD-L1 expression analysis in the clinical setting. In the future, the application of AI algorithms could serve as a valuable reference guide for pathologists while scoring PD-L1.

[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.

Immune Biomarkers in Triple-Negative Breast Cancer: Improving the Predictivity of Current Testing Methods

Triple-negative breast cancer (TNBC) poses a significant challenge in terms of prognosis and disease recurrence. The limited treatment options and the development of resistance to chemotherapy make it particularly difficult to manage these patients. However, recent research has been shifting its focus towards biomarker-based approaches for TNBC, with a particular emphasis on the tumor immune landscape. Immune biomarkers in TNBC are now a subject of great interest due to the presence of tumor-infiltrating lymphocytes (TILs) in these tumors. This characteristic often coincides with the presence of PD-L1 expression on both neoplastic cells and immune cells within the tumor microenvironment. Furthermore, a subset of TNBC harbor mismatch repair deficient (dMMR) TNBC, which is frequently accompanied by microsatellite instability (MSI). All of these immune biomarkers hold actionable potential for guiding patient selection in immunotherapy. To fully capitalize on these opportunities, the identification of additional or complementary biomarkers and the implementation of highly customized testing strategies are of paramount importance in TNBC. In this regard, this article aims to provide an overview of the current state of the art in immune-related biomarkers for TNBC. Specifically, it focuses on the various testing methodologies available and sheds light on the immediate future perspectives for patient selection. By delving into the advancements made in understanding the immune landscape of TNBC, this study aims to contribute to the growing body of knowledge in the field. The ultimate goal is to pave the way for the development of more personalized testing strategies, ultimately improving outcomes for TNBC patients.

Characterization of immune checkpoints expression and lymphocyte densities of iranian breast cancer patients; the co-expression status and clinicopathological associates

BACKGROUND

Breast malignancies are now the most common and deadliest type of neoplasms among women worldwide. Novel therapeutic approaches are needed to combat advanced stages of breast cancer. In this study, we aimed to investigate the expression and co-expression status of three immune checkpoints (PD-1, PD-L1, and LAG-3), as well as tumor-infiltrating lymphocytes (TIL) scores, and to further establish their potential correlations with clinicopathologic features.

METHODS

We performed a retrospective study on 361 pathologic samples of breast cancer. Immunohistochemistry was performed to assess the status of the immune checkpoint markers, and H&E staining was used to score TILs. The correlations of the immune checkpoint markers of tumor cells and tumor-associated immune cells and TIL scores with clinicopathological characteristics were analyzed.

RESULTS

Out of 361 assessed samples, LAG-3 was positive in 51%, while IC PD-L1 and TC PD-L1 were detectable in 36% and 8.9%, respectively. Moreover, both IC PD-L1 and LAG-3 stained positively in 24.4% of samples. IC PD-L1 expression was significantly higher in tumors with higher nuclear, mitotic, and overall grades and tubule formation. In addition, TC PD-L1 and LAG-3 exhibited a similar trend for higher overall grading. Tumors with positive estrogen- and progesterone-receptor (ER and PR) expression had significantly lower IC PD-L1 and TC PD-L1 staining, while LAG-3 positivity was more prevalent in HER2 positive samples. Tumors that were positive for these biomarkers had significantly higher Ki-67 scores. LAG-3 expression showed significant correlations with PD-1 and IC PD-L1 expression. Besides, the co-expression of LAG-3 and IC PD-L1 was significantly more encountered in luminal B and triple-negative subtypes, compared to the luminal A subtype. Regarding TILs, their scoring was significantly higher in ER and PR negative and HER2 positive samples. Intriguingly, samples with positive staining for LAG-3, IC PD-L1, and TC PD-L1 had significantly higher TIL scorings.

CONCLUSIONS

Immune checkpoints show differentially different levels of expression in certain molecular subtypes of breast cancer. Moreover, they reveal a meaningful correlation with each other, proliferation indices, and histologic grades. Finally, a sizable proportion of breast cancers co-express PD-L1 and LAG-3, which will make them appropriate targets for future combined ICIs.

Reproducibility in PD-L1 Immunohistochemistry Quantification through the Tumor Proportion Score and the Combined Positive Score: Could Dual Immunostaining Help Pathologists?

We studied the pathologists' agreements in quantifying PD-L1 expression through the tumor proportion score (TPS) and the combined positive score (CPS) using single PD-L1 immunohistochemistry (S-IHC) and double immunohistochemistry (D-IHC) combining PD-L1 staining and tumor cell markers. S-IHC and D-IHC were applied to 15 cancer samples to generate 60 digital IHC slides (30 whole slides images and 30 regions of interest of 1 mm²) for PD-L1 expression quantification using both TPS and CPS, twice by four pathologists. Agreements were estimated calculating intraclass correlation coefficients (ICC). Both S-IHC and D-IHC slides analyses resulted in excellent (for TPS, ICC > 0.9) to good (for CPS, ICC > 0.75) inter- and intra-pathologist agreements with slightly higher ICC with D-IHC than with S-IHC. S-IHC resulted in higher TPS and CPS than D-IHC (+5.6 and +6.1 mean differences, respectively). High reproducibility in the quantification of PD-L1 expression is attainable using S-IHC and D-IHC.

Role of Surgical Pathologist for Detection of Predictive Immuno-oncological Factors in Breast Cancer

Immune checkpoint inhibitors (ICIs) have changed therapy strategies in breast cancer (BC) patients suffering from triple-negative breast cancer (TNBC). For example, in Europe the anti-programmed cell death 1 ligand 1 (PD-L1) ICI Azetolizumab is approved for adult patients with locally advanced or metastasized TNBC (mTNBC), depending on the immunohistochemical (IHC) PD-L1 expression of immune cells in the tumor area [immune cell (IC) score ≥1%); the anti-programmed cell death 1 (PD-1) ICI pembrolizumab is approved for mTNBC if PD-L1 Combined Positive Score (CPS), that is PD-L1 expression on tumor and/or immune cells, is ≥10. For early TNBC, in contrast, neoadjuvant use of pembrolizumab is approved in the United States and Europe independent from PD-L1 IHC expression. The determination of PD-L1 expression in tumor tissue to predict response to ICI therapy requires sensitive immunostaining with appropriate primary antibodies and staining protocols and a standardized and meticulous assessment of PD-L1 IHC stained breast cancer tissue slides. For the selection of the test material and continuous quality control of the dyeing, high standards must be applied. The evaluation is carried out according to various evaluation algorithms (scores). Here, the role of PD-L1 in BC and the currently most relevant PD-L1 assays and scores for TNBC will be explained. Furthermore, other tissue-based biomarkers potentially predictive for ICI therapy response in BC, for example, tumor mutational burden (TMB), will be presented in this review.

Immunotherapy in Genitourinary Cancers: Role of Surgical Pathologist for Detection of Immunooncologic Predictive Factors

Genitourinary malignancies include a broad spectrum of distinct tumor entities occurring in the kidney, the urinary tract, the prostate, the adrenal glands, the penis, and testicles. Each tumor entity presents with unique biological characteristics, especially in terms of immunobiology. The immune landscape of genitourinary malignancies differs between immunoreactive tumors like urothelial carcinoma or carcinomas of the kidney, for which several immunotherapeutic treatment options have been approved in the past years. In contrast, prostate cancer presents with low immunogenicity and previous trials exploring immune checkpoint inhibitors and other immunotherapeutic agents did not proof substantial survival benefits. In this review, we are presenting a streamlined overview on the role of surgical pathologists within the contemporary practice of immune oncology. It includes current indications for pathologic programmed death-ligand 1 (PD-L1) assessment and important pathologic considerations on PD-L1 testing harmonization including interassay and algorithm variabilities. In addition, we will discuss emerging biomarkers beyond PD-L1 and their potential to predict immunotherapy responses including tumor mutational burden, microsatellite instability, gene expression signatures, and histologic factors.

Immune Checkpoint Glycoproteins Have Polymorphism: Are Monoclonal Antibodies Too Specific?

Since the 2018 Nobel prize in medicine was granted to the discovery of immune escape by cancer cells, billions of dollars have been spent on a new form of cancer immunotherapy called immune checkpoint inhibition (ICI). In this treatment modality, monoclonal antibodies (mAbs) are used to block cell-surface glycoproteins responsible for cancer immune escape. However, only a subset of patients benefit from this treatment. In this commentary, we focus on the polymorphism in the target molecules of these mAbs, namely PD-1, PD-L1 and CTLA4; we explain that using a single mAb from one clone is unlikely to succeed in treating all humans because humans have a genotype and phenotype polymorphism in these molecules. Monoclonal antibodies are highly specific and are capable of recognizing only one epitope ("monospecific"), which makes them ideal for use in laboratory animals because these animals are generationally inbred and genetically identical (isogenic). In humans, however, the encoding genes for PD-1, PD-L1 and CTLA4 have variations (alleles), and the final protein products have phenotype polymorphism. This means that small differences exist in these proteins among individual humans, rendering one mAb too specific to cover all patients. Our suggestion for the next step in advancing this oncotherapy is to focus on methods to tailor the mAb treatment individually for each patient or replace a single clone of mAb with less specific alternatives, e.g., a "cocktail of mAbs", oligoclonal antibodies or recombinant polyclonal antibodies. Fortunately, there are ongoing clinical trials on oligoclonal antibodies at the moment.

PD-L1 Expression in Triple-negative Breast Cancer-a Comparative Study of 3 Different Antibodies

BACKGROUND

Assessment of programmed death protein-ligand 1 (PD-L1) in triple-negative breast cancer (TNBC) has entered daily practice to identify patients eligible for treatment with immune checkpoint inhibitors. However, different antibodies and different cut-offs for PD-L1 positivity are used, and the interchangeability of these methods is not clear. The aim of our study was to analyze whether different PD-L1 antibodies can be used interchangeably to identify TNBC patients as PD-L1 positive.

METHODS

A tissue microarray encompassing 147 TNBC cases was immunohistochemically analyzed using 3 different antibodies against PD-L1: SP142, SP263, and E1L3N. PD-L1 positivity was determined as ≥1% of positive tumor-associated immune cells. The staining patterns of the 3 antibodies were compared and correlated with clinicopathological data.

RESULTS

A total of 84 cases were evaluable for PD-L1 analysis with all 3 antibodies. PD-L1 was positive in 50/84 patients (59.5%) with SP263, in 44/84 (52.4%) with E1L3N, and in 29/84 (34.5%) with SP142. There was no statistical difference between the performance of SP263 and E1L3N, but both antibodies stained significantly more cases than the SP142 antibody.

CONCLUSIONS

Our results show that the 3 PD-L1 antibodies identify different TNBC patient subgroups as PD-L1 positive and, therefore cannot be used interchangeably. Additional studies are needed to further investigate the use and impact of different PD-L1 antibody clones for predictive selection of TNBC patients for treatment with immune checkpoint inhibitors.

Concordance of PD-L1 expression in triple-negative breast cancers in Chinese patients: A retrospective and pathologist-based study

OBJECTIVE

To compare the expression of programmed cell death ligand 1 (PD-L1) in different paraffin blocks from the same triple-negative breast cancers (TNBC) specimen and between matched primary tumors and lymph node metastases (LNMets). We also aim to determine the interobserver agreement between pathologists trained on PD-L1 (SP142) assay in assessing TNBC.

METHODS

426 histologically confirmed TNBC cases, in which 85 have LNMets, were included in this study. A PD-L1 (SP142) assay was used to identify PD-L1 expression on tumor infiltrating immune cells (IC) and also on tumor cells (TC) in primary tumors and LNMets of TNBC by two trained pathologists. PD-L1 scoring and assessment were based on criteria in IMpassion 130 trial criteria. Concordance of PD-L1 expression in TNBC were analyzed using Kappa-test and assessed by the Kappa value.

RESULTS

Prevalence of positive PD-L1 expression (PD-L1 +) on tumor-infiltrating immune cells (PD-L1 IC+) (IC≥1%) in LNMets (49.4%) was higher than in the matched primary tumors (38.9%). Concordance of PD-L1 expression on IC between the two paraffin blocks from the same primary tumor specimen was substantial (P < 0.000, Kappa = 0.627) and was identified in 83.1% (108/130) of the selected cases. For TNBC cases with matched primary and LNMets blocks, the concordance of PD-L1IC scoring between the two blocks was moderate (P < 0.000, Kappa = 0.434). Interobserver agreement of PD-L1 assessment was 78.2% (P < 0.000, Kappa = 0.567) in primary tumors and 61.4% (P < 0.000, Kappa = 0.253) in the matched LNets.

CONCLUSION

Substantial intratumor concordance of PD-L1 scoring of the primary tumors in TNBC patients was determined, implying that immunohistochemically detection using one representative block of the primary tumor should be enough to assign the expression status of PD-L1 in clinical practice. The prevalence of PD-L1 + in lymph node metastases (LNMets) was higher than in the matched primary tumors, implying that PD-L1 detection in LNMets may provide additional PD-L1 expression information, especially in TNBC cases with PD-L1- in the matched primary breast tumors. Interobserver agreement of PD-L1 scoring in primary tumors was moderate while only fair in LNMets, implying that the additional training for PD-L1 assessment of TNBC LNMets specimens is recommended to enhance interobserver agreement.

DATA AVAILABILITY

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

MHC I Expression Predicts Response to Checkpoint Inhibitors in Metastatic Urothelial Carcinoma but Lacks Prognostic Value in Localized Disease

BACKGROUND

Loss of MHC I expression is a tumoral escape mechanism, part of the process of immunoediting. MHC expression patterns and their prognostic and predictive value have not been studied in urothelial carcinoma of the bladder (UC) so far.

OBJECTIVE

To correlate the expression of MHC I and MHC II with prognosis after curative treatment, response to chemotherapy and checkpoint inhibition.

PATIENTS AND METHODS

We analyzed different patient cohorts for their expression of MHC I(HLA-A/B/C) and II (HLA-DR/DP/DQ) and examined potential correlations with prognosis and response to cisplatin-based chemotherapy or PD-1/PD-L1 directed immunotherapy.

RESULTS AND LIMITATIONS

Overall, MHC expression was analyzed in 246 patients, and complete MHC I loss was seen in 29.7% of patients. In 35% of patients aberrant tumoral expression of MHC II was observed. In a homogeneous cohort of 149 patients with cystectomy with curative intent there were no significant differences in survival between the MHC expression groups. MHC I+ and MHC II+ patients had higher infiltration densities with CD8+ T effector cells.An analysis of 77 additional patients (cohort II) with neoadjuvant chemotherapy revealed no associations of MHC status with response defined as < pT2 pN0 in the cystectomy specimen. Lastly, we analyzed 26 patients with metastatic disease treated with PD-1/PD-L1 directed immunotherapy (cohort III, best response: 11 PD, 5 SD, 10 OR) and observed responses exclusively in MHC I+ patients (10/19 patients, 52.6). All four MHC I+ /MHC II+ /PD-L1+ patients had a progression-free interval of at least 12 months.

CONCLUSIONS

Tumoral MHC I expression is frequently lost in UC. We found no association with prognosis or response to cisplatin-based chemotherapy but response to checkpoint inhibitors was limited to MHC I+ patients.

[Immunological biomarker research in uro-oncology-using the example of urothelial cancer]

The most common malignant tumor of the urinary tract system is urothelial carcinoma (UC). With the introduction of novel immunologic therapy options in both metastatic and localized settings, the exploration of immunologic biomarkers to predict potential treatment success has become a focus of clinical translational research. For example, expression levels of programmed cell death ligand 1 (PD-L1) in UC tumors can help clinicians decide which patients are more likely to respond to immuno-oncology therapies; in light of new approvals with mandated PD-L1 testing (e.g., adjuvant nivolumab therapy after radical cystectomy), harmonization of PD-L1 testing is becoming increasingly important. However, in addition to PD-L1 determination, broader potentially predictive biomarkers such as tumor mutational burden and immune signatures/phenotypes have been and continue to be investigated in clinical trials. This review will provide a streamlined overview of existing evidence and new developments in the field of urothelial carcinoma.

Identification of New Prognostic Markers and Therapeutic Targets for Non-Muscle Invasive Bladder Cancer: HER2 as a Potential Target Antigen

Bacillus Calmette–Guérin (BCG) is the gold standard adjuvant treatment for non-muscle-invasive bladder cancer (NMIBC). However, given the current global shortage of BCG, new treatments are needed. We evaluated tumor microenvironment markers as potential BCG alternatives for NMIBC treatment. Programmed death-ligand 1, human epidermal growth factor receptor-2 (HER2), programmed cell death-1 (PD1), CD8, and Ki67 levels were measured in treatment-naïve NMIBC and MIBC patients (pTa, pT1, and pT2 stages). Univariate and multivariate Cox proportional hazard models were used to determine the impact of these markers and other clinicopathological factors on survival, recurrence, and progression. EP263, IM142, PD1, and Ki67 levels were the highest in the T2 stage, followed by the T1 and Ta stages. HER2 and IM263 expressions were higher in the T1 and T2 stages than in the Ta stage. In NMIBC, the significant prognostic factors for recurrence-free survival were adjuvant therapy, tumor grade, and HER2 positivity, whereas those for progression-free survival included age, T-stage, and IM263. Age, T-stage, EP263, PD1, CD8, and Ki67 levels were significant factors associated with overall survival. IM263 and HER2 are potential biomarkers for progression and recurrence, respectively. Therefore, we propose HER2 as a potential target antigen for intravesical therapeutics as a BCG alternative.

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.

Programmed Death-Ligand 1 (PD-L1) as Immunotherapy Biomarker in Breast Cancer

Breast cancer constitutes the most common malignant neoplasm in women around the world. Approximately 12% of patients are diagnosed with metastatic stage, and between 5 and 30% of early or locally advanced BC patients will relapse, making it an incurable disease. PD-L1 ligation is an immune inhibitory molecule of the activation of T cells, playing a relevant role in numerous types of malignant tumors, including BC. The objective of the present review is to analyze the role of PD-L1 as a biomarker in the different BC subtypes, adding clinical trials with immune checkpoint inhibitors and their applicable results. Diverse trials using immunotherapy with anti-PD-1/PD-L1 in BC, as well as prospective or retrospective cohort studies about PD-L1 in BC, were included. Despite divergent results in the reviewed studies, PD-L1 seems to be correlated with worse prognosis in the hormone receptor positive subtype. Immune checkpoints inhibitors targeting the PD-1/PD-L1 axis have achieved great response rates in TNBC patients, especially in combination with chemotherapy, making immunotherapy a new treatment option in this scenario. However, the utility of PD-L1 as a predictive biomarker in the rest of BC subtypes remains unclear. In addition, predictive differences have been found in response to immunotherapy depending on the stage of the tumor disease. Therefore, a better understanding of tumor microenvironment, as well as identifying new potential biomarkers or combined index scores, is necessary in order to make a better selection of the subgroups of BC patients who will derive benefit from immune checkpoint inhibitors.

Interassay and interobserver comparability study of four programmed death-ligand 1 (PD-L1) immunohistochemistry assays in triple-negative breast cancer

Different immunohistochemical programmed death-ligand 1 (PD-L1) assays and scorings have been reported to yield variable results in triple-negative breast cancer (TNBC). We compared the analytical concordance and reproducibility of four clinically relevant PD-L1 assays assessing immune cell (IC) score, tumor proportion score (TPS), and combined positive score (CPS) in TNBC. Primary TNBC resection specimens (n = 104) were stained for PD-L1 using VENTANA SP142, VENTANA SP263, DAKO 22C3, and DAKO 28–8. PD-L1 expression was scored according to guidelines on virtual whole slide images by four trained readers.

The mean PD-L1 positivity at IC-score ≥1% and CPS ≥1 ranged between 53% and 75% with the highest positivity for SP263 and comparable levels for 22C3, 28–8, and SP142. Inter-assay agreement was good between 28–8 and 22C3 across all scores and cut-offs (kappa 0.68–0.74) and for both assays with SP142 at IC-score ≥1% and CPS ≥1 (kappa 0.61–0.67). The agreement between SP263 and all other assays was substantially lower for all scores. Inter-reader agreement for each assay was good to excellent for IC-score ≥1% (kappa 0.73–0.78) and CPS ≥1 (kappa 0.68–0.74), fair to good for CPS ≥10 (kappa 0.52–0.67) and TPS ≥1% (kappa 0.53–0.72). The percentage of overlapping cases in the positive/negative category was >90% between IC-score ≥1% and CPS ≥1 but below when comparing IC-score ≥1% with CPS ≥10. We demonstrate an overall good inter-reader agreement for all PD-L1 assays in TNBC along with assay specific differences in positivity and concordances, which may aid to select the right test strategy in routine diagnostics.

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Different PD-L1 IHC assays and scorings may show variable results in TNBC.

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Overall good assay concordance between SP142, 22C3, and 28–8 at IC-score 1%.

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Overall good assay concordance between SP142, 22C3, and 28–8 at CPS 1.

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SP142 is less optimal for CPS assessment at higher cut-offs.

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SP263 assay is not interchangeable with the other three PD-L1 assays.

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.

Currently Used Laboratory Methodologies for Assays Detecting PD-1, PD-L1, PD-L2 and Soluble PD-L1 in Patients with Metastatic Breast Cancer

Simple Summary

Several methods targeting the programmed death protein-1 (PD-1) axis have been developed and evaluated for the detection of immune checkpoint levels that are strongly involved in immunotherapy for patients with metastatic breast cancer. Variations in different assays used in diverse studies have affected their result interpretation and clinical utility. When applying these assays to the laboratory, a comprehensive understanding of the characteristics of them should be recognized. We reviewed applied laboratory techniques for detecting PD-1, PD-ligand (L)1, PD-L2, and soluble PD-L1, which are important for selecting metastatic cancer patients for immunotherapy. Advances in methodologies according to the epoch are also investigated to gain insight into immunologic techniques and to facilitate appropriate laboratory settings for evaluating the PD-1 axis status, which are useful for estimating outcomes and planning patient-tailored immunotherapy strategies.

Abstract

Approximately 20% of breast cancer (BC) patients suffer from distant metastasis. The incidence and prevalence rates of metastatic BC have increased annually. Immune checkpoint inhibitors are an emerging area of treatment, especially for metastatic patients with poor outcomes. Several antibody drugs have been developed and approved for companion testing of the programmed death protine-1 (PD-1) axis. We reviewed currently used laboratory methodologies for assays determining PD-1 axis to provide a comprehensive understanding of principles, advantages, and drawbacks involved in their implementation. The most commonly used method is immunohistochemistry (92.9%) for PD-L1 expression using tissue samples (96.4%). The commonly used anti-PD-L1 antibody clone were commercially available 22C3 (30.8%), SP142 (19.2%), SP263 (15.4%), and E1L3N (11.5%). Enzyme-linked immunosorbent assay and electrochemiluminescent immunoassay that target soluble PD-ligand (L)1 were developed and popularized in 2019–2021, in contrast to 2016–2018. Easy accessibility and non-invasiveness due to the use of blood samples, quantitative outputs, and relatively rapid turnaround times make them more preferable. Regarding scoring methods, a combination of tumor and immune cells (45.5% in 2016–2018 to 57.1% in 2019–2021) rather than each cell alone became more popular. Information about antibody clones, platforms, scoring methods, and related companion drugs is recommended for reporting PD-L1 expression.

Interobserver Agreement of PD-L1/SP142 Immunohistochemistry and Tumor-Infiltrating Lymphocytes (TILs) in Distant Metastases of Triple-Negative Breast Cancer: A Proof-of-Concept Study. A Report on Behalf of the International Immuno-Oncology Biomarker Working Group

Patients with advanced triple-negative breast cancer (TNBC) benefit from treatment with atezolizumab, provided that the tumor contains ≥1% of PD-L1/SP142-positive immune cells. Numbers of tumor-infiltrating lymphocytes (TILs) vary strongly according to the anatomic localization of TNBC metastases. We investigated inter-pathologist agreement in the assessment of PD-L1/SP142 immunohistochemistry and TILs. Ten pathologists evaluated PD-L1/SP142 expression in a proficiency test comprising 28 primary TNBCs, as well as PD-L1/SP142 expression and levels of TILs in 49 distant TNBC metastases with various localizations. Interobserver agreement for PD-L1 status (positive vs. negative) was high in the proficiency test: the corresponding scores as percentages showed good agreement with the consensus diagnosis. In TNBC metastases, there was substantial variability in PD-L1 status at the individual patient level. For one in five patients, the chance of treatment was essentially random, with half of the pathologists designating them as positive and half negative. Assessment of PD-L1/SP142 and TILs as percentages in TNBC metastases showed poor and moderate agreement, respectively. Additional training for metastatic TNBC is required to enhance interobserver agreement. Such training, focusing on metastatic specimens, seems worthwhile, since the same pathologists obtained high percentages of concordance (ranging from 93% to 100%) on the PD-L1 status of primary TNBCs.

PD-L1 (SP142) testing is concordant between Benchmark Ultra and Bond-III stainers

Background

Atezolizumab is an inhibitor of programmed death-ligand 1 (PD-L1), used to treat advanced or metastatic bladder cancer, and in trials for non-invasive disease. In order to be eligible for treatment, patients require a PD-L1 immune cell score ≥ 5%, using the Ventana SP142 PD-L1 assay. Many laboratories do not have access to the required Ventana Benchmark Ultra stainer, and it is unclear if the assay performs similarly on other stainers. In this study, we compare SP142 assay results between Ventana Benchmark Ultra and Leica Bond-III stainers.

Methods

Serial sections of 90 samples of transurethral bladder resections (comprising 51 pTaHG, 8 pTis, 18 pT1, 10 pT2 tumors) were stained using the SP142 PD-L1 antibody on Ventana Benchmark Ultra and Leica Bond-III stainers, manually scored, and compared using accuracy and Cohen’s kappa measures.

Results

Both devices yielded highly concordant PD-L1 immune cell scores (accuracy 0.84, Cohen’s κ 0.732). Moreover, we found similar tumor cell (TC) PD-L1 scores using both stainers, and a trend towards greater TC scores in pT2 stage samples (p = 0.05).

Conclusion

This study is the first to compare the SP142 antibody in bladder cancer on two different stainers. Our results indicate that both Benchmark Ultra and Bond-III stainers yield highly concordant results using the SP142 PD-L1 antibody.

PD-L1 expression in bladder cancer: Which scoring algorithm in what tissue?

INTRODUCTION

For cisplatin-ineligible patients, approval of first-line immune-checkpoint inhibitor therapy relies on the programmed death ligand 1 (PD-L1) expression assay employed, namely, the combined positive score (CPS) or immune cell (IC) score. This study compares PD-L1 diagnostic scores and positivity in primary and matched metastatic bladder cancer tissue.

METHODS

A total of 108 patients undergoing radical cystectomy for urothelial bladder cancer and lymphatic spread (pN+) were included. PD-L1 expression was compared by immunohistochemistry (IHC) between the primary bladder tumor and associated lymph node metastases using Ventana SP263 anti-PD-L1 antibody. In a subset of cases further IHC was performed with Ventana SP142 and Dako 22C3 antibodies. Second, the PD-L1 scoring algorithms for the CPS and IC score were compared. Correlation of PD-L1 positivity with clinical parameters and tumor stage was assessed. Intra- and intertissue analyses were performed with Pearson's chi square test, McNemar test and Spearman correlation employing IBM SPSS 25.

RESULTS

PD-L1 expression did not correlate with clinicopathological parameters. The CPS (43.5% vs. 35.6%; P=0.006) and the IC score (28.7% vs. 21.2%; P=0.002) yielded PD-L1 positivity significantly more often in primary BC than in matched lymph node metastasis. Both the CPS (r=0.775; P<0.001) and the IC score (r=0.711; P<0.001) correlated between primary and metastatic bladder cancer tissue. Employing CPS vs. IC led to significantly more PD-L1-positive classified cases in primary BC (CPS vs. IC; 43.5% vs. 28.7%; P<0.001) and lymph node metastasis (CPS vs. IC; 35.6% vs. 21.2%, P<0.001).

CONCLUSION

Compared to lymph node analysis, bladder tissue yields more PD-L1 positivity assessed with the CPS and IC scores. This is particularly evident when employing the CPS. The findings highlight that employing both PD-L1 assays may maximize eligibility for first-line checkpoint-inhibitors to treat bladder cancer patients unfit for cisplatin-based chemotherapy.

Identification of the Functions and Prognostic Values of RNA Binding Proteins in Bladder Cancer

Post-transcriptional regulation plays a leading role in gene regulation and RNA binding proteins (RBPs) are the most important posttranscriptional regulatory protein. RBPs had been found to be abnormally expressed in a variety of tumors and is closely related to its occurrence and progression. However, the exact mechanism of RBPs in bladder cancer (BC) is unknown. We downloaded transcriptomic data of BC from the Cancer Genome Atlas (TCGA) database and used bioinformatics techniques for subsequent analysis. A total of 116 differentially expressed RBPs were selected, among which 61 were up-regulated and 55 were down-regulated. We then identified 12 prognostic RBPs including CTIF, CTU1, DARS2, ENOX1, IGF2BP2, LIN28A, MTG1, NOVA1, PPARGC1B, RBMS3, TDRD1, and ZNF106, and constructed a prognostic risk score model. Based on this model we found that patients in the high-risk group had poorer overall survival (P < 0.001), and the area under the receiver operator characteristic curve for this model was 0.677 for 1 year, 0.697 for 3 years, and 0.709 for 5 years. Next, we drew a nomogram based on the risk score and other clinical variables, which showed better predictive performance. Our findings contribute to a better understanding of the pathogenesis, progression and metastasis of BC. The model of these 12 genes has good predictive value and may have good prospects for improving clinical treatment regimens and patient prognosis.

Programmed Death Ligand 1 Immunohistochemistry in Triple-Negative Breast Cancer: Evaluation of Inter-Pathologist Concordance and Inter-Assay Variability

Purpose

The programmed death ligand 1 (PD-L1) SP142 assay with a 1% immune cell (IC) cutoff is approved for the selection of advanced triple-negative breast cancer (TNBC) patients for atezolizumab treatment. We aimed to evaluate the interobserver concordance of PD-L1 scoring and inter-assay variability of various PD-L1 assays in TNBC.

Methods

Thirty patients with primary TNBC were selected, and SP142, SP263, 22C3, and E1L3N assays were performed. PD-L1 staining in ICs and tumor cells (TCs) was scored by 10 pathologists who were blinded to the assay. The interobserver concordance among pathologists and the inter-assay variability of the four PD-L1 assays were analyzed. For SP142, the intraobserver concordance among the six pathologists was analyzed after training.

Results

The adjusted means of PD-L1 IC scoring ranged from 6.2% to 12.9% for the four assays; the intraclass correlations showed moderate (0.584–0.649) reader concordance. The PD-L1 IC scoring with a 1% cutoff resulted in identical scoring in 40.0%–66.7% of cases and a poor to moderate agreement (Fleiss κ statistic [FKS] = 0.345–0.534) for the four assays. The SP142 assay had the widest range of positive rate (56.5%–100.0%), lowest number of cases with identical scoring, and lowest FKS at 1% cutoff. Pairwise comparison of adjusted means showed significantly decreased PD-L1 staining in SP142 compared with the other assays in both ICs and TCs. As for the intraobserver concordance in the SP142 assay, the overall percent agreement was 87.8% with a 1% IC cutoff. After training, the proportion of cases with identical scoring at a 1% IC cutoff increased to 70.0%; the FKS also increased to 0.610.

Conclusion

The concordance of PD-L1 IC scoring among pathologists was low, at the 1% cutoff for the SP142 assay without training. SP142 showed the lowest PD-L1 expression in both IC and TC.

Integration of Spatial PD-L1 Expression with the Tumor Immune Microenvironment Outperforms Standard PD-L1 Scoring in Outcome Prediction of Urothelial Cancer Patients

Simple Summary

Diagnostic PD-L1 assessment of urothelial cancer to predict a patient’s immune therapy response remains a matter of controversy. Several contributing factors have been discussed; however, systematic studies are lacking. The present study demonstrates that clinically applied PD-L1 scoring algorithms are influenced by inter-algorithm variability and result in the selection of different “PD-L1” positive populations within the tumor immune microenvironment (TIME). The results further demonstrate that specific immune phenotypes of muscle-invasive urothelial cancer are associated with very different clinical outcomes, which cannot be resolved by PD-L1 testing. Thus, PD-L1 alone not only fails to reflect the TIME, but also has implications for patients. We conclude that a comprehensive integration of PD-L1 expression and immune phenotypes is superior to PD-L1 testing. This might be a novel strategy to predict a patient’s response to immune therapy.

Abstract

Background: Immune therapy has gained significant importance in managing urothelial cancer. The value of PD-L1 remains a matter of controversy, thus requiring an in-depth analysis of its biological and clinical relevance. Methods: A total of 193 tumors of muscle-invasive bladder cancer patients (MIBC) were assessed with four PD-L1 assays. PD-L1 scoring results were correlated with data from a comprehensive digital-spatial immune-profiling panel using descriptive statistics, hierarchical clustering and uni-/multivariable survival analyses. Results: PD-L1 scoring algorithms are heterogeneous (agreements from 63.1% to 87.7%), and stems from different constellations of immune and tumor cells (IC/TC). While Ventana IC5% algorithm identifies tumors with high inflammation and favorable baseline prognosis, CPS10 and the TCarea25%/ICarea25% algorithm identify tumors with TC and IC expression. Spatially organized immune phenotypes, which correlate either with high PD-L1 IC expression and favorable prognosis or constitutive PD-L1 TC expression and poor baseline prognosis, cannot be resolved properly by PD-L1 algorithms. PD-L1 negative tumors with relevant immune infiltration can be detected by sTILs scoring on HE slides and digital CD8⁺ scoring. Conclusions: Contemporary PD-L1 scoring algorithms are not sufficient to resolve spatially distributed MIBC immune phenotypes and their clinical implications. A more comprehensive view of immune phenotypes along with the integration of spatial PD-L1 expression on IC and TC is necessary in order to stratify patients for ICI.

[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.

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.

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.

Addressing resistance to immune checkpoint inhibitor therapy: an urgent unmet need

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of various cancers by reversing the immunosuppressive mechanisms employed by tumors to restore anticancer immunity. Although ICIs have demonstrated substantial clinical efficacy, patient response can vary in depth and duration, and many do not respond at all or eventually develop resistance. ICI resistance mechanisms can be tumor-intrinsic, related to the tumor microenvironment or patient-specific factors. Multiple resistance mechanisms may be present within one tumor subtype, or heterogeneity exists among patients with the same tumor type. Consequently, designing effective combination treatment strategies is challenging. This review will discuss ICI resistance mechanisms, and summarize findings from key preclinical and clinical trials of ICIs, to identify potential treatment strategies or pathways to overcome ICI resistance.

PD1/PD-L1 Axis in Uro-oncology

The immune system is important to control tumor development and progression in humans. However, tumor cells and cells of the tumor microenvironment can induce immune escape mechanisms including activation of immune checkpoints such as PD-1/PD-L1. Based on this knowledge, new immune therapies, including PD-1 and PD-L1 inhibition, have been developed and are already recommended as a standard treatment in metastatic bladder and kidney cancer patients. In addition to its role as a therapeutic target, PD-L1 seems to be a prognostic parameter although data are controversial. Only little is known about signaling pathways inducing PD-L1 expression in tumor cells on one hand and about its functional role for tumor cells itself. However, the understanding of the complex biological function of PD-L1 will improve therapeutic options in urological malignancies. This review is giving an overview of the current knowledge concerning the PD-1/PD-L1 axis in urological tumors including bladder, kidney, prostate, testicular and penile cancer.

Understanding PD-L1 Testing in Breast Cancer: A Practical Approach

Background

Immune checkpoint inhibitors (ICI) have changed therapy strategies for cancer patients tremendously. Some approved ICI acquire testing of PD-L1 expression on tumor and/or immune cells. However, since PD-L1 testing is a comprehensive issue with various assays, antibody clones, scoring methods, and cut-offs, we aimed to summarize the recommendations and technical and histopathological issues of diagnostic PD-L1 assessment with an emphasis on invasive breast cancer (IBC).

Summary

Besides other (pre)analytical considerations, selecting the most adequate PD-L1 immunohistochemical assay/antibody clone is important. In-house assay validation, prediagnostic training, and internal and external quality assurance should be implemented. The current most relevant PD-L1 assays and scores will be explained in this review. Moreover, recommendations for PD-L1 testing in IBC are outlined.

Key Messages

Atezolizumab plus nab-paclitaxel therapy is approved for adult patients with locally advanced or metastatic triple negative breast cancer (mTNBC), if the tumor-associated immune cells express PD-L1. - This PD-L1 immune cell positivity is defined as an immune cell (IC) score, which refers to the area occupied by PD-L1 positive immune cells (lymphocytes, dendritic cells, macrophages, and granulocytes) as a percentage of the whole tumor area. The cut-off is an IC score ≥1%. In the approval study for atezolizumab in mTNBC, IC score was assessed using the Ventana PD-L1 SP142 assay. Other assays or laboratory developed tests may be used depending on country-specific drug approvals. However, harmonization studies have to show whether other PD-L1 tests are reliable and of clinical value to predict the response of breast cancer patients to ICI.

Avelumab Maintenance Therapy for Advanced or Metastatic Urothelial Carcinoma

BACKGROUND

Platinum-based chemotherapy is standard-of-care first-line treatment for advanced urothelial carcinoma. However, progression-free survival and overall survival are limited by chemotherapy resistance.

METHODS

In a phase 3 trial, we randomly assigned patients with unresectable locally advanced or metastatic urothelial cancer who did not have disease progression with first-line chemotherapy (four to six cycles of gemcitabine plus cisplatin or carboplatin) to receive best supportive care with or without maintenance avelumab. The primary end point was overall survival, assessed among all patients who underwent randomization (overall population) and among those with tumors positive for programmed cell death ligand 1 (PD-L1). Secondary end points included progression-free survival and safety.

RESULTS

Among all 700 patients who underwent randomization, the addition of maintenance avelumab to best supportive care significantly prolonged overall survival as compared with best supportive care alone (control). Overall survival at 1 year was 71.3% in the avelumab group and 58.4% in the control group (median overall survival, 21.4 months vs. 14.3 months; hazard ratio for death, 0.69; 95% confidence interval [CI], 0.56 to 0.86; P = 0.001). Avelumab also significantly prolonged overall survival in the PD-L1-positive population; overall survival at 1 year was 79.1% in the avelumab group and 60.4% in the control group (hazard ratio, 0.56; 95% CI, 0.40 to 0.79; P<0.001). The median progression-free survival was 3.7 months in the avelumab group and 2.0 months in the control group in the overall population (hazard ratio for disease progression or death, 0.62; 95% CI, 0.52 to 0.75) and 5.7 months and 2.1 months, respectively, in the PD-L1-positive population (hazard ratio, 0.56; 95% CI, 0.43 to 0.73). The incidence of adverse events from any cause was 98.0% in the avelumab group and 77.7% in the control group; the incidence of adverse events of grade 3 or higher was 47.4% and 25.2%, respectively.

CONCLUSIONS

Maintenance avelumab plus best supportive care significantly prolonged overall survival, as compared with best supportive care alone, among patients with urothelial cancer who had disease that had not progressed with first-line chemotherapy. (Funded by Pfizer and Merck [Darmstadt, Germany]; JAVELIN Bladder 100 ClinicalTrials.gov number, NCT02603432.).

Pathological roles of c-Met in bladder cancer: Association with cyclooxygenase-2, heme oxygenase-1, vascular endothelial growth factor-A and programmed death ligand 1

c-Met is a receptor tyrosine kinase that binds a specific ligand, namely hepatocyte growth factor (HGF). The HGF/c-Met system is important for malignant aggressiveness in various types of cancer, including bladder cancer (BC). However, although phosphorylation is the essential step required for biological activation of c-Met, pathological roles of phosphorylated c-Met at the clinical and molecular levels in patients with BC are not fully understood. In the present study, the expression levels of c-Met and the phosphorylation of two of its tyrosine residues (pY1234/pY1235 and pY1349) were immunohistochemically examined in 185 BC tissues. The associations between these expression levels and cancer cell invasion, metastasis, and cyclooxygenase-2 (COX-2), heme oxygenase-1 (HO-1), VEGF-A and programmed death ligand 1 (PD-L1) levels were investigated. c-Met was associated with muscle invasion (P=0.021), as well as the expression levels of HO-1 (P=0.028) and PD-L1 (P<0.001), whereas pY1349 c-Met was associated with muscle invasion (P=0.003), metastasis (P=0.025), and COX-2 (P=0.017), HO-1 (P=0.031) and PD-L1 (P=0.001) expression. By contrast, pY1234/1235 c-Met was associated with muscle invasion and metastasis (P=0.006 and P=0.012, respectively), but not with the panel of cancer-associated molecules. Furthermore, COX-2 and PD-L1 expression were associated with muscle invasion and metastasis, respectively (P=0.045 and P=0.036, respectively). Hence, c-Met serves important roles in muscle invasion by regulating HO-1 and PD-L1, whereas its phosphorylation at Y1349 is associated with muscle invasion and metastasis via the regulation of COX-2, HO-1 and PD-L1 in patients with BC. Furthermore, phosphorylation at Y1234/1235 may lead to muscle invasion and metastasis via alternate mechanisms associated with c-Met and pY1349 c-Met.

Development and applications of computer image analysis algorithms for scoring of PD-L1 immunohistochemistry

Immune checkpoint inhibitors targeting programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) have rapidly become integral to standard-of-care therapy for non-small cell lung cancer and other cancers. Immunohistochemical (IHC) staining of PD-L1 is currently the accepted and approved diagnostic assay for selecting patients for PD-L1/PD-1 axis therapies in certain indications. However, the inherent biological complexity of PD-L1 and the availability of several PD-L1 assays – each with different detection systems, platforms, scoring algorithms and cut-offs – have created challenges to ensure reliable and reproducible results based on subjective visual assessment by pathologists. The increasing adoption of computer technologies into the daily workflow of pathology provides an opportunity to leverage these tools towards improving the clinical value of PD-L1 IHC assays. This review describes several image analysis software programs of computer-aided PD-L1 scoring in the hope of driving further discussion and technological advancement in digital pathology and artificial intelligence approaches, particularly as precision medicine evolves to encompass accurate simultaneous assessment of multiple features of cancer cells and their interactions with the tumor microenvironment.

The path to a better biomarker: application of a risk management framework for the implementation of PD-L1 and TILs as immuno-oncology biomarkers in breast cancer clinical trials and daily practice

Immune checkpoint inhibitor therapies targeting PD-1/PD-L1 are now the standard of care in oncology across several hematologic and solid tumor types, including triple negative breast cancer (TNBC). Patients with metastatic or locally advanced TNBC with PD-L1 expression on immune cells occupying ≥1% of tumor area demonstrated survival benefit with the addition of atezolizumab to nab-paclitaxel. However, concerns regarding variability between immunohistochemical PD-L1 assay performance and inter-reader reproducibility have been raised. High tumor-infiltrating lymphocytes (TILs) have also been associated with response to PD-1/PD-L1 inhibitors in patients with breast cancer (BC). TILs can be easily assessed on hematoxylin and eosin-stained slides and have shown reliable inter-reader reproducibility. As an established prognostic factor in early stage TNBC, TILs are soon anticipated to be reported in daily practice in many pathology laboratories worldwide. Because TILs and PD-L1 are parts of an immunological spectrum in BC, we propose the systematic implementation of combined PD-L1 and TIL analyses as a more comprehensive immuno-oncological biomarker for patient selection for PD-1/PD-L1 inhibition-based therapy in patients with BC. Although practical and regulatory considerations differ by jurisdiction, the pathology community has the responsibility to patients to implement assays that lead to optimal patient selection. We propose herewith a risk-management framework that may help mitigate the risks of suboptimal patient selection for immuno-therapeutic approaches in clinical trials and daily practice based on combined TILs/PD-L1 assessment in BC. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Therapeutic implications of PD-L1 expression in bladder cancer with squamous differentiation

Background

Immune checkpoint inhibitors (ICI) are an integral part of bladder cancer therapy, however, the relevance of ICI treatment for mixed and pure squamous cell carcinoma of the bladder remains poorly studied. Therefore, we analysed the expression of programmed death-ligand 1 (PD-L1) in urothelial carcinomas with squamous differentiation (UC/SCC) and pure squamous cell carcinoma (SCC) of the bladder and studied a UC/SCC patient with ICI therapy.

Methods

Tissue microarrays of 45 UC/SCC and 63 SCC samples were immunohistochemically stained with four anti-PD-L1 antibodies (28–8, 22C3, SP142 and SP263). PD-L1 expression was determined for tumour cells (TP-Score), immune cells (IC-Score) and combined (CPS, combined positive score). In addition, we present clinical and histological data of an UC/SCC patient with nivolumab therapy.

Results

Overall, positive PD-L1 staining ranged between 4.8 and 61.9% for IC and 0 and 51.2% for TC depending on the used antibody. There were no significant differences between UC/SCC and SCC. According to current FDA guidelines for example for first line therapy of urothelial cancer with pembrolizumab (CPS ≥ 10), a subset of SCC patients up to 20% would be eligible. Finally, our UC/SCC index patient revealed excellent therapy response regarding his lung metastasis.

Conclusions

Our data reveal a PD-L1 expression in squamous differentiated carcinomas comparable with current data shown for urothelial tumours. In accordance with the encouraging clinical data of the index patient we suggest ICI treatment also for mixed and pure SCC of the urinary bladder.

Profiles of Immune Infiltration in Bladder Cancer and its Clinical Significance: an Integrative Genomic Analysis

Tumor-infiltrating immune cells are closely related to the prognosis of bladder cancer. Analysis of tumor infiltrating immune cells is usually based on immunohistochemical analysis. Since many immune cell marker proteins are not specific for different immune cells, which may induce misleading or incomplete. CIBERSORT is an algorithm to estimate specific cell types in a mixed cell population using gene expression data. In this study, the CIBERSORT algorithm was used to identify the immune cell infiltration signatures. The gene expression profiles, mutation data, and clinical data were collected from The Cancer Genome Atlas (TCGA) database. Unsupervised consensus clustering was used to acquire the immune cell infiltration subtypes of bladder cancer based on the fractions of 22 immune cell types. Four immune cell clusters with different immune infiltrate and mutation characteristics were identified. In addition, this stratification has a prognostic relevance, with cluster 2 having the best outcome, cluster 1 the worst. These clusters showed distinct mRNA expression patterns. The characteristic genes in subtype cluster 1 were mainly involved in cell division, those in subtype cluster 2 were mainly related in antigen processing and presentation, those in subtype cluster 3 were mainly involved in epidermal cell differentiation, and those in subtype cluster 4 were mainly related in the humoral immune response. These differences may affect the development of the bladder cancer, the sensitivity to treatment as well as the prognosis. Through further validation, this study may contribute to the development of personalized therapy and precision medical treatments.

Identification of gene expression profiles and immune cell infiltration signatures between low and high tumor mutation burden groups in bladder cancer

Bladder cancer is one of the most commonly diagnosed tumors and is results from the accumulation of somatic mutations in the DNA. Tumor mutation burden (TMB) has been associated with cancer immunotherapeutic response. In this study, we attempted to explore the correlation between TMB and cancer prognosis. Identify the different expressed genes and immune cell infiltration signatures between low and high TMB group. Mutation data, gene expression profiles and clinical data were downloaded from The Cancer Genome Atlas (TCGA) database. Patients were divided into high and low TMB groups, allowing differentially expressed genes (DEGs) to be identified. Functional enrichment and protein-protein interaction (PPI) network analysis were used to identify the functions of the DEGs. And immune cell infiltration signatures were evaluated by CIBERSORT algorithm. These results shown that high TMB was significantly associated with prognosis. We obtained a list of TMB related genes which may influence the infiltrations of immune cells. We also found a higher proportion of CD8 T cells, CD4 T cells and NK cells in the high TMB group. Our data suggest that higher TMB tends to promote the infiltrations of T cells and NK cells and patients with higher TMB may achieve a more favorable prognosis in bladder cancer.

The Evolving Landscape of Biomarkers for Anti-PD-1 or Anti-PD-L1 Therapy

The administration of antibodies blocking the immune checkpoint molecules programmed cell death protein 1 (PD-1) or programmed cell death 1 ligand 1 (PD-L1) has evolved as a very promising treatment option for cancer patients. PD-1/PD-L1 inhibition has significantly enhanced expansion, cytokine secretion, and cytotoxic activity of CD4⁺ and CD8⁺ T lymphocytes, resulting in enhanced antitumor responses. Anti-PD-1 or anti-PD-L1 therapy has induced tumor regression and improved clinical outcome in patients with different tumor entities, including melanoma, non-small-cell lung cancer, and renal cell carcinoma. These findings led to the approval of various anti-PD-1 or anti-PD-L1 antibodies for the treatment of tumor patients. However, the majority of patients have failed to respond to this treatment modality. Comprehensive immune monitoring of clinical trials led to the identification of potential biomarkers distinguishing between responders and non-responders, the discovery of modes of treatment resistance, and the design of improved immunotherapeutic strategies. In this review article, we summarize the evolving landscape of biomarkers for anti-PD-1 or anti-PD-L1 therapy.