PD-L1 and prognosis in patients with malignant pleural mesothelioma: a meta-analysis and bioinformatics study

Immunotherapy for advanced and recurrent malignant pleural mesothelioma

OBJECTIVES

This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To assess the effects of immune checkpoint inhibitors (single-agent or combination therapy) in people with advanced malignant pleural mesothelioma in a first-line or salvage setting.

PD-L1 expression complements CALGB prognostic scoring system in malignant pleural mesothelioma

Background

Programmed death ligand-1 (PD-L1) expression is a predictive biomarker in patients with lung cancer, but its role in malignant pleural mesothelioma (MPM) remains unclear. Evidence suggests that higher PD-L1 expression is correlated with worse survival. CALGB is the main scoring system used to predict the benefit of chemotherapy treatment. This study aimed to determine the prognostic value of PD-L1 expression and its addition to CALGB scoring system in patients with MPM.

Methods

In this retrospective analysis, we evaluated samples with confirmed locally advanced or metastatic MPM. PD-L1 Tumor Proportional Score (TPS) was determined by immunohistochemistry at diagnosis.

Results

73 patients were included in this study. A cutoff value of 15 was set for a high or low PD-L1 TPS. In total, 71.2% (n=52) and 28.8% (n=21) of individuals harbored low or high PD-L1 expression, respectively. PD-L1High was associated with worse median progression-free Survival (mPFS) [4.9 vs. 10.8 months; HR 2.724, 95% CI (1.44-5.14); p = 0.002] and Overall Survival (OS) [6.0 vs. 20.9 months; HR 6.87, 95% CI (3.4-8.7); p<0.001] compared to patients with PD-L1Low. Multivariate analysis confirmed that PD-L1 expression was an independent factor for PFS and OS in patients with MPM and CALGB score of 5-6.

Conclusion

PD-L1 addition to CALGB scale improves its prognostic estimation of MPM survival and should be considered in future research.

Sarcomatoid urothelial carcinoma of the renal pelvis treated with immunotherapy

BACKGROUND

Sarcomatoid carcinoma is a rare, high-grade malignancy with epithelial and mesenchymal components. It may be a good candidate for immunotherapy because it is associated with overexpression of programmed cell death ligand 1. Sarcomatoid urothelial carcinoma (UC) of the upper urinary tract is extremely rare. Here we report the first case of sarcomatoid UC of the renal pelvis that responded to immunotherapy.

CASE PRESENTATION

A 79-year-old man was referred to our hospital complaining of various symptoms, including anorexia and abdominal pain. A computed tomography scan revealed a right atrial tumor, a 9 cm left renal mass with a renal vein tumor thrombus, para-aortic lymphadenopathy, and multiple small lung nodules. The patient underwent resection of the right atrial tumor. Pathological analysis of the tumor did not lead to an accurate diagnosis even after several rounds of immunohistochemistry. He underwent a needle biopsy of the left kidney and was initially diagnosed with collecting duct carcinoma, a rare subtype of renal cell carcinoma (RCC). Following the initial diagnosis, immunotherapy with nivolumab and ipilimumab commenced. Thereafter, almost all lesions, including the left renal tumor, were reduced in size. However, he underwent a left nephrectomy approximately a year after beginning immunotherapy due to repeated left renal bleeding. Histological examination of the nephrectomy specimen revealed two forms of cancer-sarcomatoid UC and conventional high-grade UC. Two months after surgery, the patient was found to have new lung metastases. He underwent chemotherapy with gemcitabine and cisplatin, followed by immunotherapy with pembrolizumab. However, both treatments were ineffective. The patient died of cancer 19 months after his first admission.

CONCLUSIONS

The presented case of sarcomatoid UC of the renal pelvis that partially responded to immunotherapy suggests that immunotherapy can be a promising treatment for sarcomatoid UC.

Thiolate DNAzymes on Gold Nanoparticles for Isothermal Amplification and Detection of Mesothelioma-derived Exosomal PD-L1 mRNA

Catalytic DNAzymes have been used for isothermal amplification and rapid detection of nucleic acids, holding the potential for point-of-care testing applications. However, when Subzymes (universal substrate and DNAzyme) are tethered to the polystyrene magnetic microparticles via biotin-streptavidin bonds, the residual free Subzymes are often detached from the microparticle surface, which causes a significant degree of false positives. Here, we attached dithiol-modified Subzyme to gold nanoparticle and improved the limit of detection (LoD) by 200 times compared to that using magnetic microparticles. As a proof of concept, we applied our new method for the detection of exosomal programed cell-death ligand 1 (PD-L1) RNA. As the classical immune checkpoint, molecule PD-L1, found in small extracellular vesicles (sEVs, traditionally called exosomes), can reflect the antitumor immune response for predicting immunotherapy response. We achieved the LoD as low as 50 fM in detecting both the RNA homologous to the PD-L1 gene and exosomal PD-L1 RNAs extracted from epithelioid and nonepithelioid subtypes of mesothelioma cell lines, which only takes 8 min of reaction time. As the first application of isothermal DNAzymes for detecting exosomal PD-L1 RNA, this work suggests new point-of-care testing potentials toward clinical translations.

The Genes-Stemness-Secretome Interplay in Malignant Pleural Mesothelioma: Molecular Dynamics and Clinical Hints

MPM has a uniquely poor somatic mutational landscape, mainly driven by environmental selective pressure. This feature has dramatically limited the development of effective treatment. However, genomic events are known to be associated with MPM progression, and specific genetic signatures emerge from the exceptional crosstalk between neoplastic cells and matrix components, among which one main area of focus is hypoxia. Here we discuss the novel therapeutic strategies focused on the exploitation of MPM genetic asset and its interconnection with the surrounding hypoxic microenvironment as well as transcript products and microvesicles representing both an insight into the pathogenesis and promising actionable targets.

A novel prognostic nomogram for predicting survival in diffuse pleural mesothelioma

Recent advances in the management of diffuse pleural mesothelioma (DPM) have increased interest in prognostication and risk stratification on the basis that maximum benefit of combination immunotherapy appears to be seen in patients who otherwise would have the worst prognosis. Various grading schemes have been proposed, including the recently published Mesothelioma Weighted Grading Scheme (MWGS). However, predictive modelling using deep learning algorithms is increasingly regarded as the gold standard in prognostication. We therefore sought to develop and validate a prognostic nomogram for DPM. Data from 369 consecutive patients with DPM were used as independent training and validation cohorts to develop a prognostic tool that included the following variables: age, sex, histological type, nuclear atypia, mitotic count, necrosis, and BAP1 immunohistochemistry. Patients were stratified into four risk groups to assess model discrimination and calibration. To assess discrimination, the area-under-the-curve (AUC) of a receiver-operator-curve (ROC), concordance-index (C-index), and dissimilarity index (D-index) were calculated. Based on the 5-year ROC analysis, the AUC for our model was 0.75. Our model had a C-index of 0.67 (95% CI 0.53-0.79) and a D-index of 2.40 (95% CI 1.69-3.43). Our prognostic nomogram for DPM is the first of its kind, incorporates well established prognostic markers, and demonstrates excellent predictive capability. As these factors are routinely assessed in most pathology laboratories, it is hoped that this model will help inform prognostication and difficult management decisions, such as patient selection for novel therapies. This nomogram is now freely available online at: https://nomograms.shinyapps.io/Meso_Cox_ML/.

Immunotherapy approaches for malignant pleural mesothelioma

Over the past decade, immune-checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer. In mesothelioma, a rare cancer with a dismal prognosis generally caused by exposure to asbestos, treatment with single or dual ICIs results in robust improvements in overall survival over previous standard-of-care therapies, both in the first-line and relapsed disease settings. Predictive biological features that underpin response to ICIs remain poorly understood; however, insights into the immune microenvironment and genomic landscape of mesothelioma as well as into their association with response or acquired resistance to ICIs are emerging. Several studies of rational combinations involving ICIs with either another ICI or a different agent are ongoing, with emerging evidence of synergistic antitumour activity. Non-ICI-based immunotherapies, such as peptide-based vaccines and mesothelin-targeted chimeric antigen receptor T cells, have demonstrated promising efficacy. Moreover, results from pivotal trials of dendritic cell vaccines and viral cytokine delivery, among others, are eagerly awaited. In this Review, we comprehensively summarize the key steps in the development of immunotherapies for mesothelioma, focusing on strategies that have led to randomized clinical evaluation and emerging predictors of response. We then forecast the future treatment opportunities that could arise from ongoing research.

The Predictive and Prognostic Nature of Programmed Death-Ligand 1 in Malignant Pleural Mesothelioma: A Systematic Literature Review

Introduction

Given the emergence of combination of programmed cell death protein-1 and CTLA4 pathway blockade as effective treatment options in malignant pleural mesothelioma (MPM), there is interest in the extent to which programmed death-ligand 1 (PD-L1) expression may be prognostic of clinical outcomes and predictive of response to anti-programmed death (ligand) 1 (PD-[L]1) therapies.

Methods

MEDLINE and EMBASE electronic databases were searched until November 4, 2020. English-language randomized trials and observational studies that reported clinical outcomes and PD-L1 expression in adult patients (>18 or >20 y) with MPM were included. Forest plots were used to descriptively summarize clinical outcome data across studies.

Results

A total of 29 publications were identified providing data on the research question. Among the studies in which anti-PD-(L)1 therapies were not specified to have been used, 63% (10 of 16) found patients with tumors expressing PD-L1 (typically >1%) to have poorer survival than those with tumors expressing lower levels of PD-L1. Among the studies in which anti-PD-(L)1 therapies were used, 83% (five of six) did not reveal an association between survival and PD-L1 tumor expression. The single study directly comparing outcomes between those treated and untreated with anti-PD-(L)1 therapies across different PD-L1 cutoffs did not identify any differences between the groups.

Conclusions

The quality and consistency of the existing evidence base are currently insufficient to draw conclusions regarding a prognostic or predictive role of PD-L1 in MPM. Furthermore, high-quality studies on this topic are required to support the use of PD-L1 as a biomarker in MPM.

Prognostic Function of Programmed Cell Death-Ligand 1 in Esophageal Squamous Cell Carcinoma Patients Without Preoperative Therapy: A Systematic Review and Meta-Analysis

Background

Studies investigating the correlation between the expression of programmed cell death-ligand 1 (PD-L1) and prognosis in patients with esophageal squamous cell carcinoma (ESCC) not receiving preoperative therapy have increased significantly, but conclusions remain inconclusive. Therefore, this study aimed to determine the association between clinical outcomes and expression of PD-L1 in ESCC patients without preoperative therapy.

Methods

We conducted a comprehensive literature search using four databases up to May 2020. Quality assessment was carried out according to the Newcastle-Ottawa Quality Assessment Scale (NOS). Hazard ratios (HRs) were used to analyze the association between PD-L1 expression with prognosis. Furthermore, we evaluated the correlation between PD-L1 and clinicopathological characteristics using odds ratios (ORs) and 95% confidence intervals (CIs).

Results

Twenty studies (19 publications) comprising 3,677 patients were included in this meta-analysis. We found that the expression of PD-L1 was not related to overall survival (OS, HR: 1.16, 95% CI: 0.94-1.42, p = 0.16) or disease-free survival (DFS, HR: 0.85, 95% CI: 0.66-1.10, p = 0.21) in ESCC. Furthermore, although PD-L1 expression was not significantly associated with sex, degree of differentiation, TNM stage, T stage, lymph node status, smoking, or alcohol use, the merged OR demonstrated that the expression of PD-L1 was higher in older patients compared to younger patients (OR: 1.40, 95% CI: 1.07-1.83, p = 0.01). No obvious publication bias was observed.

Conclusions

Our present study illustrated that PD-L1 expression was not related to poor prognosis of ESCC patients not receiving preoperative therapy, albeit the association only showed a tendency for statistical significance. Notably, PD-L1 expression showed a significant association with age. This meta-analysis had several limitations; therefore, our results need to be verified through further large-scale and prospective studies.

IL-27 Mediates PD-L1 Expression and Release by Human Mesothelioma Cells

Malignant mesothelioma (MM) is a rare tumor with an unfavorable prognosis. MM genesis involves asbestos-mediated local inflammation, supported by several cytokines, including IL-6. Recent data showed that targeting PD-1/PD-L1 is an effective therapy in MM. Here, we investigated the effects of IL-6 trans-signaling and the IL-6-related cytokine IL-27 on human MM cells in vitro by Western blot analysis of STAT1/3 phosphorylation. The effects on PD-L1 expression were tested by qRT-PCR and flow-cytometry and the release of soluble (s)PD-L1 by ELISA. We also measured the concentrations of sPD-L1 and, by multiplexed immunoassay, IL-6 and IL-27 in pleural fluids obtained from 77 patients in relation to survival. IL-27 predominantly mediates STAT1 phosphorylation and increases PD-L1 gene and surface protein expression and sPD-L1 release by human MM cells in vitro. IL-6 has limited activity, whereas a sIL-6R/IL-6 chimeric protein mediates trans-signaling predominantly via STAT3 phosphorylation but has no effect on PD-L1 expression and release. IL-6, IL-27, and sPD-L1 are present in pleural fluids and show a negative correlation with overall survival, but only IL-27 shows a moderate albeit significant correlation with sPD-L1 levels. Altogether these data suggest a potential role of IL-27 in PD-L1-driven immune resistance in MM.

Tumor Immune Microenvironment and Genetic Alterations in Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and fatal disease of the pleural lining. Up to 80% of the MPM cases are linked to asbestos exposure. Even though its use has been banned in the industrialized countries, the cases continue to increase. MPM is a lethal cancer, with very little survival improvements in the last years, mirroring very limited therapeutic advances. Platinum-based chemotherapy in combination with pemetrexed and surgery are the standard of care, but prognosis is still unacceptably poor with median overall survival of approximately 12 months. The genomic landscape of MPM has been widely characterized showing a low mutational burden and the impairment of tumor suppressor genes. Among them, BAP1 and BLM are present as a germline inactivation in a small subset of patients and increases predisposition to tumorigenesis. Other studies have demonstrated a high frequency of mutations in DNA repair genes. Many therapy approaches targeting these alterations have emerged and are under evaluation in the clinic. High-throughput technologies have allowed the detection of more complex molecular events, like chromotripsis and revealed different transcriptional programs for each histological subtype. Transcriptional analysis has also paved the way to the study of tumor-infiltrating cells, thus shedding lights on the crosstalk between tumor cells and the microenvironment. The tumor microenvironment of MPM is indeed crucial for the pathogenesis and outcome of this disease; it is characterized by an inflammatory response to asbestos exposure, involving a variety of chemokines and suppressive immune cells such as M2-like macrophages and regulatory T cells. Another important feature of MPM is the dysregulation of microRNA expression, being frequently linked to cancer development and drug resistance. This review will give a detailed overview of all the above mentioned features of MPM in order to improve the understanding of this disease and the development of new therapeutic strategies.

[Research Progress of Immune Checkpoint Inhibitors in Malignant Pleural Mesothelioma]

Malignant pleural mesothelioma (MPM) is a malignant tumor with strong invasiveness, low survival rate and lack of effective treatment options. As the only first-line treatment plan for the advanced MPM, combination of pemetrexed and cisplatin chemotherapy have been existing since the last 20 years. Immunotherapy has long been considered as a potential treatment plan for MPM, mainly including immune checkpoint inhibitors (ICIs), immunotoxin therapy, anti-cancer vaccine and adoptive T-cell therapy. This review focuses on summarizing the current research status of immune checkpoint inhibitors in MPM, discusses the effect of tumor heterogeneity on ICIs treatment, and describes that the biomarker-oriented immunotherapy is a new vision for the realization of individualized treatment of MPM.
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Pathological Characterization of Tumor Immune Microenvironment (TIME) in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and highly aggressive disease that arises from pleural mesothelial cells, characterized by a median survival of approximately 13-15 months after diagnosis. The primary cause of this disease is asbestos exposure and the main issues associated with it are late diagnosis and lack of effective therapies. Asbestos-induced cellular damage is associated with the generation of an inflammatory microenvironment that influences and supports tumor growth, possibly in association with patients' genetic predisposition and tumor genomic profile. The chronic inflammatory response to asbestos fibers leads to a unique tumor immune microenvironment (TIME) composed of a heterogeneous mixture of stromal, endothelial, and immune cells, and relative composition and interaction among them is suggested to bear prognostic and therapeutic implications. TIME in MPM is known to be constituted by immunosuppressive cells, such as type 2 tumor-associated macrophages and T regulatory lymphocytes, plus the expression of several immunosuppressive factors, such as tumor-associated PD-L1. Several studies in recent years have contributed to achieve a greater understanding of the pathogenetic mechanisms in tumor development and pathobiology of TIME, that opens the way to new therapeutic strategies. The study of TIME is fundamental in identifying appropriate prognostic and predictive tissue biomarkers. In the present review, we summarize the current knowledge about the pathological characterization of TIME in MPM.

Malignant pleural mesothelioma: clinical experience and prognostic value of derived neutrophil-to-lymphocyte ratio and PD-L1 expression

BACKGROUND

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor, with a poor prognosis. MPM needs to find prognostic factors of survival. We provided the management of patients with MPM and sought to determine whether pre-treatment levels of derived neutrophil-to-lymphocyte ratio (dNLR) as well as PD-L1 expression were reliable prognostic factors of survival.

METHODS

We conducted a single-institution retrospective study, including all patients with MPM treated at La Paz University Hospital between December 2009 and March 2018. Baseline disease, demographics, clinical data, treatment characteristics and complete blood cell counts were collected. We examined dNLR at baseline and data for PD-L1 expression were analyzed in tumor cells by immunohistochemistry.

RESULTS

We included 25 patients. The median overall survival (OS) was 15.7 months (95% CI 11.3-20.0). 5 patients had a dNLR greater than 3 (20%). Patients with a dNLR greater than 3 had shorter median OS (8.5 months), than patients with a dNLR less than 3 (17.0 months), with statistically significant differences (p = 0.038). Ten patients (40%) had positive PD-L1 expression (≥ 1%). Patients with positive PD-L1 expression had shorter median OS (8.5 months) than patients with negative PDL1 expression (15.7 months), but without statistically significant association (p = 0.319).

CONCLUSION

The survival data obtained in our sample are consistent with those previously reported. Pretreatment levels of dNLR greater than 3 and positive PD-L1 expression could be significant prognostic factors for poor survival in patients with MPM. Further and prospective studies are needed to explore this relationship and to derive definitive conclusions.

Biomarkers for Malignant Pleural Mesothelioma-A Novel View on Inflammation

Malignant pleural mesothelioma (MPM) is an aggressive disease with limited treatment response and devastating prognosis. Exposure to asbestos and chronic inflammation are acknowledged as main risk factors. Since immune therapy evolved as a promising novel treatment modality, we want to reevaluate and summarize the role of the inflammatory system in MPM. This review focuses on local tumor associated inflammation on the one hand and systemic inflammatory markers, and their impact on MPM outcome, on the other hand. Identification of new biomarkers helps to select optimal patient tailored therapy, avoid ineffective treatment with its related side effects and consequently improves patient's outcome in this rare disease. Additionally, a better understanding of the tumor promoting and tumor suppressing inflammatory processes, influencing MPM pathogenesis and progression, might also reveal possible new targets for MPM treatment. After reviewing the currently available literature and according to our own research, it is concluded that the suppression of the specific immune system and the activation of its innate counterpart are crucial drivers of MPM aggressiveness translating to poor patient outcome.