Clinical safety and activity of pembrolizumab in patients with malignant pleural mesothelioma (KEYNOTE-028): preliminary results from a non-randomised, open-label, phase 1b trial

A Role for PET/CT in response assessment of malignant pleural mesothelioma

Malignant pleural mesothelioma is a rare type of cancer, whose incidence, however, is increasing and will presumably continue to rise in the coming years. Key features of this disease comprise its mantle-shaped, pleura-associated, often multifocal growth, which cause diagnostic challenges. A growing number of mesotheliomas are being treated with novel immunotherapies for which no image derived general response criteria have been established. However, recent studies indicate that FDG-PET/CT could be superior for response assessment compared to CT-based criteria. This article aims at providing an overview of response assessment criteria dedicated to malignant pleural mesothelioma, such as mRECIST, iRECIST, and PERCIST. In addition, the potential future role of PET/CT in the management of malignant pleural mesothelioma will also be discussed.

Advances in Drug Treatments for Mesothelioma

INTRODUCTION

The paucity of the therapeutic armamentarium currently available for patients with malignant mesothelioma clearly represents a huge unmet need. Over the last years, based on new advances in understanding the biology of mesothelioma, new therapeutic approaches have been investigated.

AREAS COVERED

In this manuscript, the literature data regarding the advances in drug treatment for patients with mesothelioma are critically reviewed, focusing particularly on immunotherapy and targeted therapy.

EXPERT OPINION

The latest findings on immunotherapy and targeted therapy are changing the therapeutic armamentarium for mesothelioma. However, mesothelioma comprises of genomically different subtypes and the phenotypic diversity combined with the rarity of this disease represents a major criticality in developing new effective therapies. Although the first clinical data are encouraging, the treatment's stratification by molecular characteristics for mesothelioma is only at the beginning. Luckily, the rapid improvement of understanding the biology of mesothelioma is producing new opportunities in discovering new therapeutic targets to test in pre-clinical settings and to transfer in the clinical setting. In this evolving scenario, the future perspectives for mesothelioma patients seem really promising.

[Advances in Immunotherapy for Malignant Pleural Mesothelioma]

Patients with malignant pleural mesothelioma (MPM) usually present with poor prognosis and short survival period, and there has been a lack of effective treatment options for a long time. Chemotherapy has limited improvement in the clinical outcome of advanced patients (the median survival is less than one year), and it is difficult to find suitable targets for targeted therapy. Recent in-depth research on immunotherapy has changed the treatment pattern of MPM. Especially, the dual immunotherapy regimen significantly improved the survival outcome of patients across subgroups and prolonged the survival time of MPM patients. Therefore, it has been approved for unresectable MPM as first-line treatment for patients. The exploration of other mono or combo immunotherapy regimens in the first and second-line settings of MPM is also underway. How to identify the best beneficial population of each regimen through predictive biomarkers is also a hot spot for researchers. This article will focus on the most up-to-date progress of MPM epidemiology, histological characteristics, pathogenesis, treatment patterns and the advances of immunotherapy in the disease.
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Gemcitabine-facilitated modulation of the tumor microenvironment and PD-1/PD-L1 blockade generate a synergistic antitumor effect in a murine hepatocellular carcinoma model

BACKGROUND

Gemcitabine can alter the immunogenic microenvironments, and the effect of gemcitabine plus programmed death-1 (PD-1)/ programmed death-ligand 1 (PD-L1) blockade in hepatocellular carcinoma (HCC) is investigated.

METHODS

Subcutaneous H22-green fluorescent protein (GFP) cells inoculation model was constructed and treated with gemcitabine, anti-PD-1 antibody (αPD-1), or the combination every four days when the tumor volumes reached about 50 mm³. Four days after the final treatment, primary tumor tissues were resected and dissociated, which were further subcutaneously injected on the contralateral side to construct the HCC relapse model. The infiltrated proportion of immune cells and PD-1 expression were quantified by flow cytometry. The relative content of transforming growth factor (TGF)-β, interleukin (IL)-12p70, and interferon (IFN)-γ were detected by the enzyme-linked immunosorbent assay (ELISA). Tumor volume and the number of tumor-free mice were evaluated.

RESULTS

Gemcitabine treatment can effectively increase the total proportion of infiltrating immune cells, reduce the proportion of myeloid-derived suppressor cells (MDSCs) and macrophages, and increase T cells proportion without significant growth inhibition. While after gemcitabine treatment, PD-L1 expression on tumor cells and PD-1 on T cells were significantly up-regulated. Subcutaneous tumors volume were reduced considerably after gemcitabine plus αPD-1 treatment compared with gemcitabine (P<0.01) or αPD-1 monotherapy (P<0.001) with the increased proportion of IL-2⁺CD8⁺T, CD8⁺T central memory cells (TCM), CD4 TCM, up-regulated IL12p70 and IFN-γ secretion, and down-regulated TGF-β. Gemcitabine plus αPD-1 blockade could inhibit the relapse tumor model as indicated with down-regulated tumor volume and increased number of tumor-free mice.

CONCLUSION

Gemcitabine up-regulates the proportion of intratumor CD8⁺T and the relative expression of PD-1/PD-L1, and the combination of PD-1/PD-L1 blockade can further inhibit the growth and the relapse of HCC.

ERS International Congress 2021: highlights from Assembly 8 Thoracic Surgery and Lung Transplantation

The thoracic surgery and lung transplantation assembly of the European Respiratory Society (ERS) is delighted to present the highlights from the 2021 International ERS Congress. We have selected four sessions that discussed recent advances across a wide range of topics: including digital health surveillance in thoracic surgery, emerging concepts in pulmonary metastasectomy, advances in mesothelioma care, and novel developments in lung graft allocation and monitoring. The sessions are summarised by early career members in close collaboration with the assembly faculty. We aim to give the reader an update on the highlights of the conference in the fields of thoracic surgery and lung transplantation.

Recent Advances of Immune Checkpoint Inhibition and Potential for (Combined) TIGIT Blockade as a New Strategy for Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a fatal cancer type that affects the membranes lining the lungs, and is causally associated with asbestos exposure. Until recently, the first-line treatment consisted of a combination of chemotherapeutics that only had a limited impact on survival, and had not been improved in decades. With the recent approval of combined immune checkpoint inhibition for MPM, promising new immunotherapeutic strategies are now emerging for this disease. In this review, we describe the current preclinical and clinical evidence of various immune checkpoint inhibitors in MPM. We will consider the advantages of combined immune checkpoint blockade in comparison with single agent checkpoint inhibitor drugs. Furthermore, recent evidence suggests a role for T cell immunoglobulin and ITIM domain (TIGIT), an inhibitory immunoreceptor, as a novel target for immunotherapy. As this novel immune checkpoint remains largely unexplored in mesothelioma, we will discuss the potential of TIGIT blockade as an alternative therapeutic approach for MPM. This review will emphasize the necessity for new and improved treatments for MPM, while highlighting the recent advances and future perspectives of combined immune checkpoint blockade, particularly aimed at PD-L1 and TIGIT.

An Update on Emerging Therapeutic Options for Malignant Pleural Mesothelioma

The treatment paradigm for malignant pleural mesothelioma (MPM) has changed little in the last 18 years. Radical intent treatment, consisting of surgical resection, radiotherapy and chemotherapy, has been offered to a highly select few; however, there is little randomised evidence to validate this approach. Prior to 2020 chemotherapy with platinum and an anti-folate was the only intervention with randomised evidence to demonstrate improved overall survival (OS) in MPM. No systemic therapy had been demonstrated to improve OS in the second line setting until 2020. The publication of the Checkmate 743 trial in 2021 demonstrated a survival benefit of combination immunotherapy over standard chemotherapy in newly diagnosed patients with MPM. This finding was shortly followed by the CONFIRM trial which demonstrates a modest but significant survival benefit of second line nivolumab versus placebo in patients having previously received standard chemotherapy. The results of these trials, recent biomarker directed therapy and chemotherapy adjuncts are discussed within this review. The integration of immunotherapy for the few patients in whom radical surgical therapy is intended is currently the subject of clinical trials and offers the prospect of improving outcomes in this rare but devastating disease.

Immunotherapy for mesothelioma: Moving beyond single immune check point inhibition

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm with low survival rates. Platinum-based chemotherapy has represented the cornerstone of treatment for over a decade, prompting the investigation of new therapeutic strategies both in the early stage of the disease and in the advanced setting. The advent of immune check-point inhibitors (ICIs) has recently revamped the enthusiasm for using immunotherapy also in MPM. However, results from first clinical trials using single immune check-point inhibition have been conflicting, and this may be mainly attributed to the lack of specific biomarkers as well as to intra- and inter- patient heterogeneity. The phase III Checkmate743 firstly demonstrated the superiority of an ICI combination (nivolumab plus ipilimumab) over chemotherapy in the first-line treatment of unresectable MPM, leading to FDA approval of this regimen and showing that moving beyond single immune check point inhibition might be a successful strategy to overcome resistance in the majority of MPM patients. In this review, we describe the emerging immunotherapy strategies for the treatment of MPM. We also discuss how refining the approach in pre-clinical studies towards a more holistic perspective (which takes into account not only genetic but also pathophysiological vulnerabilities) and strengthening multi-institutional collaboration in clinical trials is finally helping the clinical development of immunotherapy in MPM.

New Era for Malignant Pleural Mesothelioma: Updates on Therapeutic Options

Malignant pleural mesothelioma (MPM) is a rare malignancy with few treatment options. Recent advances have led to US Food and Drug Administration approvals and changes in the standard of care with a novel biomedical device approved for use with platinum-pemetrexed, and also for immunotherapy agents to be included as a frontline treatment option in unresectable disease. Although predictive biomarkers for systemic therapy are not currently in use in clinical practice, it is essential to correctly identify the MPM histology to determine an optimal treatment plan. Patients with nonepithelioid MPM may have a greater magnitude of benefit to dual immunotherapy checkpoint inhibitors and this regimen should be preferred in the frontline setting for these patients. However, all patients with MPM can derive benefit from immunotherapy treatments, and these agents should ultimately be used at some point during their treatment journey. There are ongoing studies in the frontline unresectable setting that may further define the frontline therapy space, but a critical area of research will need to focus on the immunotherapy refractory population. This review article will describe the new developments in the areas of biology with genomics and chromothripsis, and also focus on updates in treatment strategies in radiology, surgery, radiation, and medical oncology with cellular therapies. These recent innovations are generating momentum to find better therapies for this disease.

Current Management and Future Perspective in Pleural Mesothelioma

Pleural mesothelioma is an aggressive malignancy arising from pleural mesothelial cell lining, predominantly associated with prior exposure to asbestos. The ban on asbestos use has led to its lower incidence in many countries, but globally the disease burden is expected to rise. Therefore, well-planned research is needed to develop more effective, tolerable and affordable drugs. The development of novel treatment has been too slow, with only two regimens of systemic therapy with robust phase 3 data approved formally to date. The treatment scenario for resectable disease remains controversial. However, recent developments in the understanding of disease and clinical trials have been encouraging, and may add better treatment options in the coming years. In this review, we discuss the current treatment options for pleural mesothelioma and shed light on some recent studies and ongoing trials.

Novel and Future Treatment Options in Mesothelioma: A Systematic Review

Mesothelioma is a rare tumor, frequently associated with asbestos exposure, arising from pleura and peritoneum. Traditionally, diagnosis and treatment have been difficult in a clinical setting. The treatment is based on a trimodal approach involving surgery, chemotherapy, and radiotherapy. The introduction of chemotherapy improved the overall survival. However, the regimen of pemetrexed/cisplatin doublet has not been changed as a standard treatment since 2004. Novel combinations of ipilimumab and nivolumab have only been approved for clinical use in late 2020. The aim of this review was to systematically summarize findings on novel treatment options in mesothelioma. We searched available medical databases online, such as PubMed and Clinicaltrials.gov, to systematically review the literature on novel approaches in immunotherapy, vaccines, and Chimeric Antigen Receptor (CAR)-T cell therapy in mesothelioma. We manually screened 1127 articles on PubMed and 450 trials on ClinicalTrials.gov, and 24 papers and 12 clinical trials published in the last ten years were included in this review. Immunotherapy that was swiftly introduced to treat other thoracic malignancies was slow to reach desirable survival endpoints in mesothelioma, possibly due to limited patient numbers. Novel treatment approaches, such as CAR-T cell therapy, are being investigated. As the incidence of mesothelioma is still rising globally, novel treatment options based on a better understanding of the tumor microenvironment and the genetic drivers that modulate it are needed to support future precision-based therapies.

Protocol of DREAM3R: DuRvalumab with chEmotherapy as first-line treAtment in advanced pleural Mesothelioma-a phase 3 randomised trial

INTRODUCTION

There is a strong theoretical rationale for combining checkpoint blockade with cytotoxic chemotherapy in pleural mesothelioma and other cancers. Two recent single-arm, phase 2 trials [DuRvalumab with chEmotherapy as first-line treAtment in advanced pleural Mesothelioma (DREAM) and Phase II multicenter study of anti-PD-L1, durvalumab, in combination with cisplatin and pemetrexed for the first-line treatment of unresectable malignant pleural mesothelioma (PrE0505)] combining the programmed death ligand-1 (PD-L1) inhibitor durvalumab with standard first-line chemotherapy exceeded prespecified safety and activity criteria to proceed to a phase 3 confirmatory trial to assess this combination. We present the protocol of the DREAM3R trial.

METHODS AND ANALYSIS

This multicentre open-label randomised trial will recruit 480 treatment-naïve adults with advanced pleural mesothelioma, randomised (2:1) to either 3-weekly durvalumab 1500 mg plus 3-weekly doublet chemotherapy (cisplatin 75 mg/m2 or carboplatin, Area Under the Curve,AUC 5 and pemetrexed 500 mg/m2) 4-6 cycles, followed by 4-weekly durvalumab 1500 mg until disease progression, unacceptable toxicity or patient withdrawal; OR doublet chemotherapy alone for 4-6 cycles, followed by observation. The target accrual time is 27 months, with follow-up for an additional 24 months. This provides over 85% power if the true HR for overall survival (OS) is 0.70, with two-sided alpha of 0.05, assuming a median OS of 15 months in the control group. Randomisation is stratified by age (18-70 years vs >70), sex, histology (epithelioid vs non-epithelioid), platinum agent (cisplatin vs carboplatin) and region (USA vs Australia/New Zealand vs Other). The primary endpoint is OS. Secondary endpoints include progression-free survival, objective tumour response (by mRECIST V.1.1 and iRECIST), adverse events, health-related quality of life and healthcare resource use. Tertiary correlative objectives are to explore and validate potential prognostic and/or predictive biomarkers (including features identified in the DuRvalumab with chEmotherapy as first-line treAtment in advanced pleural Mesothelioma (DREAM) and PrE0505 studies, PD-L1 expression, tumour mutational burden, genomic characteristics and human leukocyte antigen subtypes) in tissue and serial blood samples. An imaging databank will be assembled for validation of radiological measures of response, and studies of possible radiomic biomarkers in mesothelioma.

ETHICS AND DISSEMINATION

The protocol was approved by human research ethics review committees for all participating sites. Results will be disseminated in peer-reviewed journals and at scientific conferences.

DRUG SUPPLY

AstraZeneca.

PROTOCOL VERSION

CTC 0231 / TOGA 18/001 / PrE0506 3.0, 29 July 2021.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT04334759 ACTRN 12620001199909.

G6PD functions as a metabolic checkpoint to regulate granzyme B expression in tumor-specific cytotoxic T lymphocytes

Background

Granzyme B is a key effector of cytotoxic T lymphocytes (CTLs), and its expression level positively correlates with the response of patients with mesothelioma to immune checkpoint inhibitor immunotherapy. Whether metabolic pathways regulate Gzmb expression in CTLs is incompletely understood.

Methods

A tumor-specific CTL and tumor coculture model and a tumor-bearing mouse model were used to determine the role of glucose-6-phosphate dehydrogenase (G6PD) in CTL function and tumor immune evasion. A link between granzyme B expression and patient survival was analyzed in human patients with epithelioid mesothelioma.

Results

Mesothelioma cells alone are sufficient to activate tumor-specific CTLs and to enhance aerobic glycolysis to induce a PD-1^hi Gzmb^lo CTL phenotype. However, inhibition of lactate dehydrogenase A, the key enzyme of the aerobic glycolysis pathway, has no significant effect on tumor-induced CTL activation. Tumor cells induce H3K9me3 deposition at the promoter of G6pd, the gene that encodes the rate-limiting enzyme G6PD in the pentose phosphate pathway, to downregulate G6pd expression in tumor-specific CTLs. G6PD activation increases acetyl-coenzyme A (CoA) production to increase H3K9ac deposition at the Gzmb promoter and to increase Gzmb expression in tumor-specific CTLs converting them from a Gzmb^lo to a Gzmb^hi phenotype, thus increasing CTL tumor lytic activity. Activation of G6PD increases Gzmb⁺ tumor-specific CTLs and suppresses tumor growth in tumor-bearing mice. Consistent with these findings, GZMB expression level was found to correlate with increased survival in patients with epithelioid mesothelioma.

Conclusion

G6PD is a metabolic checkpoint in tumor-activated CTLs. The H3K9me3/G6PD/acetyl-CoA/H3K9ac/Gzmb pathway is particularly important in CTL activation and immune evasion in epithelioid mesothelioma.

The efficacy of immune checkpoint inhibitors in thoracic malignancies

The advent of immune checkpoint inhibitors (ICIs) has rapidly transformed the treatment paradigm for multiple cancer types, including thoracic malignancies. In advanced non-small cell lung cancer (NSCLC), ICIs have shifted treatment paradigm and improved overall survival reaching almost one-third of patients alive at 5 years. ICIs therapies have also modified the therapeutic strategy in first-line setting in metastatic small-cell lung cancer (SCLC) patients as well as in malignant pleural mesothelioma (MPM) improving the overall survival compared with standard treatment. This phenomenon is of huge relevance as both SCLC and MPM were considered orphan diseases without any significant improvement in the therapeutic strategy in the first-line setting during the last 15 years. In this review, we aim to review the efficacy of ICI in thoracic malignancies either in monotherapy or in combination, according to predictive biomarkers, and to the US Food and Drug Administration and the European Medicines Agency approvals of treatment strategies. We address the efficacy of these agents, especially in NSCLC according to PD-L1 expression and histologic subtype.

Malignant pleural mesothelioma: an update

Malignant mesotheliomas are rare types of cancers that affect the mesothelial surfaces, usually the pleura and peritoneum. They are associated with asbestos exposure, but due to a latency period of more than 30 years and difficult diagnosis, most cases are not detected until they reach advanced stages. Treatment options for this tumor type are very limited and survival ranges from 12 to 36 months. This review discusses the molecular physiopathology, current diagnosis, and latest therapeutic options for this disease.

Immunotherapy, the promise for present and future of malignant pleural mesothelioma (MPM) treatment

Due to occupational asbestosis exposure, the incidence of malignant pleural mesothelioma (MPM) has continuously increased over the last 30 years, with a plateau anticipated around the year 2030 in Western countries. Molecular MPM carcinogenesis involves alterations of NF2, RASSF1, LATS2WT1, p16, as well as BAP-1tumor-suppressor genes, which usually regulate apoptosis, cell invasion, motility, cell division, chromatin remodeling, as well as control of DNA repair. In few selected patients, debulking surgery consisting of pleurectomy-decortication is carried out, resulting in unsatisfactory long-term results. For about 15 years, first-line chemotherapy has been primarily based on a doublet of pemetrexed and cisplatin. Adding the monoclonal antibody bevacizumab (Avastin®), which targets vascular endothelial growth factor (VEGF), has been shown to improve overall survival (OS) by nearly 19 months. The emergence of immune check-point inhibitors (ICIs) in MPM treatment has recently been associated with substantial survival improvements in both second- and first-line settings. Similarly to non-small-cell lung cancer (NSCLC) patients, on-going trials are presently exploring the chemotherapy-ICI combination in MPM management, and depending on their results, this combination could represent a further major advance in this previously orphan disease. The current article reviews recent clinical trial results, as well as future clinical developments in this moving field.

Wedding of Molecular Alterations and Immune Checkpoint Blockade: Genomics as a Matchmaker

The development of checkpoint blockade immunotherapy has transformed the medical oncology armamentarium. But despite its favorable impact on clinical outcomes, immunotherapy benefits only a subset of patients, and a substantial proportion of these individuals eventually manifest resistance. Serious immune-related adverse events and hyperprogression have also been reported. It is therefore essential to understand the molecular mechanisms and identify the drivers of therapeutic response and resistance. In this review, we provide an overview of the current and emerging clinically relevant genomic biomarkers implicated in checkpoint blockade outcome. US Food and Drug Administration-approved molecular biomarkers of immunotherapy response include mismatch repair deficiency and/or microsatelliteinstability and tumor mutational burden of at least 10 mutations/megabase. Investigational genomic-associated biomarkers for immunotherapy response include alterations of the following genes/associated pathways: chromatin remodeling (ARID1A, PBRM1, SMARCA4, SMARCB1, BAP1), major histocompatibility complex, specific (eg, ultraviolet, APOBEC) mutational signatures, T-cell receptor repertoire, PDL1, POLE/POLD1, and neo-antigens produced by the mutanome, those potentially associated with resistance include β2-microglobulin, EGFR, Keap1, JAK1/JAK2/interferon-gamma signaling, MDM2, PTEN, STK11, and Wnt/Beta-catenin pathway alterations. Prospective clinical trials are needed to assess the role of a composite of these biomarkers to optimize the implementation of precision immunotherapy in patient care.

Immune checkpoint inhibitor therapy for malignant pleural mesothelioma

Mesothelioma is a rare and universally fatal cancer linked to exposure to asbestos. Until recently, standard of care treatment was chemotherapy; a treatment resulting in a minimal survival extension, and not improved upon for almost twenty years. However, the advent of cancer immunotherapy - and in particular the immune checkpoint inhibitor class of drugs - has resulted in recently approved new treatment options, with more currently under investigation. Here, we review clinical trials of both single agent and combination checkpoint inhibitors in mesothelioma, plus studies investigating their combination with chemotherapy. We also describe current advances in biomarker identification regarding prediction of patient response to checkpoint inhibitors. Finally, we assess the probable future direction of the field; including where current and developing technologies are likely to lead - in terms of both biomarker discovery and treatment options.

Durvalumab with platinum-pemetrexed for unresectable pleural mesothelioma: survival, genomic and immunologic analyses from the phase 2 PrE0505 trial

Mesothelioma is a rare and fatal cancer with limited therapeutic options until the recent approval of combination immune checkpoint blockade. Here we report the results of the phase 2 PrE0505 trial (NCT02899195) of the anti-PD-L1 antibody durvalumab plus platinum-pemetrexed chemotherapy for 55 patients with previously untreated, unresectable pleural mesothelioma. The primary endpoint was overall survival compared to historical control with cisplatin and pemetrexed chemotherapy; secondary and exploratory endpoints included safety, progression-free survival and biomarkers of response. The combination of durvalumab with chemotherapy met the pre-specified primary endpoint, reaching a median survival of 20.4 months versus 12.1 months with historical control. Treatment-emergent adverse events were consistent with known side effects of chemotherapy, and all adverse events due to immunotherapy were grade 2 or lower. Integrated genomic and immune cell repertoire analyses revealed that a higher immunogenic mutation burden coupled with a more diverse T cell repertoire was linked to favorable clinical outcome. Structural genome-wide analyses showed a higher degree of genomic instability in responding tumors of epithelioid histology. Patients with germline alterations in cancer predisposing genes, especially those involved in DNA repair, were more likely to achieve long-term survival. Our findings indicate that concurrent durvalumab with platinum-based chemotherapy has promising clinical activity and that responses are driven by the complex genomic background of malignant pleural mesothelioma.

In a phase 2 trial, the combination of chemotherapy with durvalumab, an anti-PD-L1 antibody, exhibited promising clinical activity in patients with previously untreated, unresectable mesothelioma, with additional analyses providing insights into genomic and immunologic features potentially associated with response.

The Role of Immunotherapy in the Treatment of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma is a rare and aggressive malignancy arising from mesothelial cells that line the serous membranes of the body. Cytotoxic chemotherapy has been a mainstay of therapy, resulting in a modest improvement in overall survival, but toxicity limits the eligible patient population. Few targeted agents beyond bevacizumab have demonstrated superior efficacy compared to placebos. With an improved understanding of the relationship between the immune system and cancer progression, immunotherapies are playing a greater role in the treatment of many cancers. Several early- and late-phase trials in malignant pleural mesothelioma, including assessments of the first-line efficacy of combination ipilimumab/nivolumab treatment, have now demonstrated promising results for both immune checkpoint inhibition and cell-based therapies. These immune therapies are likely to play a central role in the treatment of this disease going forward.

Efficacy of chemotherapy for malignant pleural mesothelioma according to histology in a real-world cohort

CheckMate 743 trial demonstrated survival benefit of immunotherapy in first line in MPM with some differences in the efficacy of chemotherapy according to histology. The objective of this study is to characterize the impact of chemotherapy according to histology in patients diagnosed with MPM at our institution. Clinical records of all MPM patients diagnosed at Vall d'Hebron University Hospital between November 2002 and April 2020 were reviewed. Associations between clinical variables and outcomes were assessed with Cox regression models. Survival data were calculated by the Kaplan-Meier method. 189 patients were included with 76% of tumors classified as epithelioid subtype. First line chemotherapy was offered to 85% of patients. Median survival in overall population was 21.3 months (95% CI 17.2-24.3). We found that patients with epithelioid tumors had better overall survival (OS) and progression free survival (PFS). Median OS of epithelioid patients treated with first line chemotherapy was 26.7 months versus 15.0 months in non-epithelioid patients (HR 2.25 CI 95% 1.4-3.4; p < 0.001). Median PFS for patients with epithelioid tumors treated with chemotherapy was 4.8 months versus 3.6 months in non-epithelioid (HR 1.5 CI 95% 1.0-2.3; p = 0.03). The improvement of outcomes in patients with epithelioid histology was detected in patients treated with cisplatin or carboplatin. Histology was not a predictive factor for the platinum agent sensitivity (p of interaction PFS = 0.09, p of interaction OS = 0.65). In our series, patients with non-epithelioid tumors presented worse prognosis. Although epithelioid tumors exposed to cisplatin had higher PFS, histology was not a clear predictor of chemotherapy efficacy.

[The Current Therapy of Asbestos-Associated Malignant Pleural Mesothelioma - An Expert Consensus Paper]

Asbestos-related mesotheliomas belong to the group of the most frequent occupational diseases in Germany, reaching about 1,000 new cases per year. The disease has a dismal prognosis because most tumors remain asymptomatic for a long time and therefore are diagnosed as incidental findings at later stages.During the last decade the German Social Accident Insurance (DGUV) has made considerable efforts to prepone the diagnosis in order to detect the disease at earliest possible stages. These efforts resulted in new findings showing that, in a high-risk group, a combination of the biomarkers calretinin and mesothelin was able to advance the diagnosis up to 12 months.Ideally, the diagnosis of a mesothelioma at an early stage has to be accompanied by the best possible individualized therapy. Standard therapeutic strategies are surgery and chemotherapy, added by radiotherapy and psycho-oncology. In recent years, several new therapeutic avenues are being explored. This review comprehensively presents both old and new therapeutic options in mesothelioma, based on international Leitlinien and new studies.

Biological basis for novel mesothelioma therapies

Mesothelioma is an aggressive cancer that is associated with exposure to asbestos. Although asbestos is banned in several countries, including the UK, an epidemic of mesothelioma is predicted to affect middle-income countries during this century owing to their heavy consumption of asbestos. The prognosis for patients with mesothelioma is poor, reflecting a failure of conventional chemotherapy that has ultimately resulted from an inadequate understanding of its biology. However, recent work has revolutionised the study of mesothelioma, identifying genetic and pathophysiological vulnerabilities, including the loss of tumour suppressors, epigenetic dysregulation and susceptibility to nutrient stress. We discuss how this knowledge, combined with advances in immunotherapy, is enabling the development of novel targeted therapies.

Phase 2 Study of YS110, a Recombinant Humanized Anti-CD26 Monoclonal Antibody, in Japanese Patients With Advanced Malignant Pleural Mesothelioma

Introduction

YS110, a humanized monoclonal antibody with a high affinity to CD26, exhibited promising antitumor activity and was generally well-tolerated in the phase 1 part of a phase 1 and 2 Japanese trial in patients with malignant pleural mesothelioma (MPM). Here we report the results of the phase 2 part of the study.

Methods

The patients included were aged 20 years and older, had histologically confirmed MPM, were refractory to or intolerant of existing antineoplastic agents, and were not candidates for standard therapy. YS110 6 mg/kg, determined in the phase 1 dose-determination part, was given in 6-weekly cycles (5 × once-weekly infusions, followed by a 1-wk rest).

Results

The study included 31 patients (median age = 68 y, 90.3% men); 64.5% had stage IV MPM, 90.3% had greater than or equal to 20% CD26 expression in tumor tissue, and 38.7% (12 patients) had previously received nivolumab. The 6-month disease control rate was 3.2%. The best overall response was partial response in one patient and stable disease in 14 patients. The median progression-free survival was 2.8 months (both in patients who had and had not previously received nivolumab—groups A and B, respectively). Respective progression-free survival rates at 6 months were 9.1% and 31.6% in groups A and B. The median overall survival was 9.7 months. A total of 30 patients (96.8%) had at least one adverse event. Common treatment-related adverse events were infusion-related reaction (16.1%), hiccups (9.7%), and interstitial lung disease (9.7%). There were no treatment-related deaths.

Conclusions

The 6-month disease control rate did not exceed the predefined threshold, but YS110 revealed modest efficacy in response rate as salvage therapy in difficult-to-treat patients with MPM. YS110 was generally well tolerated.

Management of Advanced Pleural Mesothelioma-At the Crossroads

The management of pleural mesothelioma has changed with the demonstration that first-line checkpoint blockade therapy improves survival. This review covers issues of relevance to the practicing medical oncologist, with an emphasis on the palliative setting and on new information. Until recently, standard systemic therapy for mesothelioma was combination chemotherapy with platinum and pemetrexed. In 2020, combination immunotherapy with ipilimumab and nivolumab was approved as first-line systemic therapy for mesothelioma following release of the results from the CheckMate 743 trial. This trial showed improved overall survival for patients receiving ipilimumab and nivolumab over those treated with platinum and pemetrexed chemotherapy. When the survival results were examined by histologic subtype, the survival benefit was most significant in those with nonepithelioid mesothelioma, a group for which combination immunotherapy is now standard of care. The most important outstanding issue from CheckMate-743 is a better understanding, through translational studies, of which patients with epithelioid mesothelioma may benefit from combination immunotherapy. The next generation of first-line clinical trials in mesothelioma will report the results of first-line combination chemoimmunotherapy. For those patients who receive first-line dual checkpoint blockade, there is no evidence as to the efficacy of subsequent chemotherapy. However, given the known first-line efficacy of cisplatin or carboplatin and pemetrexed, combination chemotherapy is an appropriate subsequent choice for those who progress on or after dual immunotherapy. For those who previously received chemotherapy without immunotherapy, single-agent nivolumab provides benefit over best supportive care. In summary, both chemotherapy and immunotherapy should be considered for all patients during their disease course. Another topical issue is the growing appreciation that some individuals have an inherited predisposition to mesothelioma; referral to a clinical geneticist should be considered under some circumstances. The role of surgery and multimodality therapy is controversial, with results awaited from the fully recruited MARS-2 clinical trial. Patient selection, staging, and multidisciplinary review are critical to identify those who might benefit from a multimodality approach. Finally, a proactive, multidisciplinary approach to symptom management and the principles of management of pleural effusions are critical to manage the symptom burden of mesothelioma and optimize patient well-being.

T cell receptor repertoire characteristics both before and following immunotherapy correlate with clinical response in mesothelioma

Background

Malignant pleural mesothelioma (MPM) is a highly lethal malignancy in need for new treatment options. Although immunotherapies have been shown to boost a tumor-specific immune response, not all patients respond and prognostic biomarkers are scarce. In this study, we determined the peripheral blood T cell receptor β (TCRβ) chain repertoire of nine MPM patients before and 5 weeks after the start of dendritic cell (DC)-based immunotherapy.

Materials and methods

We separately profiled PD1⁺ and PD1⁻CD4⁺ and CD8⁺ T cells, as well as Tregs and analyzed 70 000 TCRβ sequences per patient.

Results

Strikingly, limited TCRβ repertoire diversity and high average clone sizes in total CD3⁺ T cells before the start of immunotherapy were associated with a better clinical response. To explore the differences in TCRβ repertoire prior-DC-therapy and post-DC-therapy, for each patient the TCRβ clones present in the total CD3⁺ T cell fractions were classified into five categories, based on therapy-associated frequency changes: expanding, decreasing, stable, newly appearing and disappearing clones. Subsequently, the presence of these five groups of clones was analyzed in the individual sorted T cell fractions. DC-therapy primarily induced TCRβ repertoire changes in the PD1⁺CD4⁺ and PD1⁺CD8⁺ T cell fractions. In particular, in the PD1⁺CD8⁺ T cell subpopulation we found high frequencies of expanding, decreasing and newly appearing clones. Conversion from a PD1⁻ to a PD1⁺ phenotype was significantly more frequent in CD8⁺ T cells than in CD4⁺ T cells. Hereby, the number of expanding PD1⁺CD8⁺ T cell clones—and not expanding PD1⁺CD4⁺ T cell clones following immunotherapy positively correlated with overall survival, progression-free survival and reduction of tumor volume.

Conclusion

We conclude that the clinical response to DC-mediated immunotherapy is dependent on both the pre-existing TCRβ repertoire of total CD3⁺ T cells and on therapy-induced changes, in particular expanding PD1⁺CD8⁺ T cell clones. Therefore, TCRβ repertoire profiling in sorted T cell subsets could serve as predictive biomarker for the selection of MPM patients that benefit from immunotherapy.

Trial registration number

NCT02395679.

Current evidence and future perspectives of immune-checkpoint inhibitors in unresectable malignant pleural mesothelioma

Platinum-based chemotherapy is commonly used as the standard first-line treatment for unresectable malignant pleural mesothelioma (MPM). However, in recent times, immune-checkpoint inhibitors (ICIs) have led to a paradigm shift. Herein, we review relevant literature and ongoing trials of ICIs used as both first-line and salvage therapies. Specifically, in the Japanese single-arm, phase II trial, the MERIT trial, nivolumab, an antiprogrammed cell death 1 (PD-1) antibody showed favorable efficacy when used as a salvage therapy. Currently, multiple ICI monotherapy or combination therapy trials have been conducted, which could provide further evidence. Among available ICIs, the anti-PD-1 antibody is promising for unresectable MPM, despite the limited efficacy of anti-CTLA4 monotherapy. Ongoing studies will further confirm the potential efficacy of ICIs for MPM, as observed across other malignancies. It is also crucial to identify any clinically useful predictive biomarkers that could reveal ICIs with maximal effects in MPM.

Novel and Promising Systemic Treatment Approaches in Mesothelioma

OPINION STATEMENT

There was limited progress in the development of novel systemic approaches in the treatment of advanced malignant mesothelioma for years following the publication of the pivotal phase III trial of Vogelzang et al. that established the cisplatin/pemetrexed regimen as a standard 1st-line systemic therapy. Since then, over the last several years, a significant step forward has been made, with incorporation of immune checkpoint inhibitors and anti-angiogenic agents. In addition, better appreciation of mesothelioma biology has allowed detection of novelmolecular therapeutic targets. All the above-mentioned strategies, along with the additional promising approaches represented by adoptive T cell therapy, dendritic cell therapy, cancer vaccines, oncoviral therapy, and agents targeting mesothelin are discussed in this review. The clinical research to identify effective biologic targets and treatment combinations in malignant mesothelioma is ongoing.

Treatment Patterns and Outcomes of Patients With Advanced Pleural Mesothelioma at an Academic Referral Centre

BACKGROUND

Overall survival (OS) for malignant pleural mesothelioma (MPM) in vulnerable subgroups remains poorly understood with scarce data available to guide treatment decisions. The study describes real-world detailed treatment patterns and outcomes of patients with advanced MPM overall and specifically in elderly and poor performance status (PS) patients.

METHODS

Retrospective chart review was performed for all patients with histologically confirmed MPM seen at University Health Network/Princess Margaret Cancer Centre (UHN-PM).

RESULTS

A total of 667 patients with MPM were identified and 304 advanced-disease MPM (aMPM) patients had continuing care at UHN-PM (UP-cohort). In the UP-cohort, 77% of patients received ≥ one line of systemic treatment. Systemic therapy trial participation was 39%. Patients not treated with systemic therapy (29%) were more likely to be ≥ 75 years and PS ≥ 2. Median OS was 15.3 months (95%CI 13.6-18.3), with longer survival in treated vs. untreated patients (17.4 vs. 10.6 months; P = .01). Longer survival with systemic treatment was seen in patients ≥75 years (12.7 vs. 6.6 months) and patients with poor PS (9.1 vs. 5.9 months). Median progression-free-survival (PFS) and OS for patients treated with second-line therapy was poor (3.0 and 8.9 months, respectively).

DISCUSSION

In our real-world analysis of patients with aMPM treated at an academic referral centre, systemic treatment was given to the majority of patients and benefit was seen even in the elderly and poor PS patients frequently underrepresented in clinical trials. Trial participation was potentially facilitated by the formation of a dedicated multidisciplinary MPM clinic.

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.

Pleural mesothelioma (PM) - The status of systemic therapy

Pleural mesothelioma (PM) remains a malignancy with poor prognosis. Despite initial disappointing response rates to single-agent chemotherapy, upfront platinum and anti-folate-based combination chemotherapy has remained the backbone of treatment for PM for the last three decades. The role of maintenance chemotherapy remains unclear; switch-maintenance gemcitabine has shown improvements in progression-free but not overall survival. The addition of antiangiogenic agents to chemotherapy yielded modest improvements in survival, both upfront in combination with platinum-pemetrexed, and in the relapsed setting. Immunotherapy, particularly PD-(L)1 inhibitors, has shown important but variable effectiveness in relapsed PM when used as monotherapy, and is an important salvage treatment after first-line chemotherapy. Furthermore, the randomized phase 3 trial of ipilimumab-nivolumab versus platinum-pemetrexed chemotherapy demonstrated improved overall survival favouring ipilimumab-nivolumab (HR 0.74, 96.6% CI 0.60-0.91; p = 0.0020), establishing this regimen as the new standard first-line treatment for PM, particularly in those with non-epithelioid histology. Increased interest in PM genomics has led to development of novel personalized therapeutics, such as those targeting DNA repair and EZH2 pathways, however with variable outcomes in trials. Targeting the membrane glycoprotein mesothelin and arginine deprivation are other important strategies under ongoing investigation. The field of PM is changing and new treatments bring hope to a largely lethal and poor prognostic malignancy. Despite these developments, current challenges include understanding the role of combination and multimodality treatments, drivers of resistance to treatment, and establishing predictive biomarkers to improve patient selection and treatment sequencing.

A vision of immuno-oncology: the Siena think tank of the Italian network for tumor biotherapy (NIBIT) foundation

BACKGROUND

The yearly Think Tank Meeting of the Italian Network for Tumor Biotherapy (NIBIT) Foundation, brings together in Siena, Tuscany (Italy), experts in immuno-oncology to review the learnings from current immunotherapy treatments, and to propose new pre-clinical and clinical investigations in selected research areas. MAIN: While immunotherapies in non-small cell lung cancer and melanoma led to practice changing therapies, the same therapies had only modest benefit for patients with other malignancies, such as mesothelioma and glioblastoma. One way to improve on current immunotherapies is to alter the sequence of each combination agent. Matching the immunotherapy to the host's immune response may thus improve the activity of the current treatments. A second approach is to combine current immunotherapies with novel agents targeting complementary mechanisms. Identifying the appropriate novel agents may require different approaches than the traditional laboratory-based discovery work. For example, artificial intelligence-based research may help focusing the search for innovative and most promising combination partners.

CONCLUSION

Novel immunotherapies are needed in cancer patients with resistance to or relapse after current immunotherapeutic drugs. Such new treatments may include targeted agents or monoclonal antibodies to overcome the immune-suppressive tumor microenvironment. The mode of combining the novel treatments, including vaccines, needs to be matched to the patient's immune status for achieving the maximum benefit. In this scenario, specific attention should be also paid nowadays to the immune intersection between COVID-19 and cancer.

The Updating of Biological Functions of Methyltransferase SETDB1 and Its Relevance in Lung Cancer and Mesothelioma

SET domain bifurcated 1 (SETDB1) is a histone H3 lysine 9 (H3K9) methyltransferase that exerts important effects on epigenetic gene regulation. SETDB1 complexes (SETDB1-KRAB-KAP1, SETDB1-DNMT3A, SETDB1-PML, SETDB1-ATF7IP-MBD1) play crucial roles in the processes of histone methylation, transcriptional suppression and chromatin remodelling. Therefore, aberrant trimethylation at H3K9 due to amplification, mutation or deletion of SETDB1 may lead to transcriptional repression of various tumour-suppressing genes and other related genes in cancer cells. Lung cancer is the most common type of cancer worldwide in which SETDB1 amplification and H3K9 hypermethylation have been indicated as potential tumourigenesis markers. In contrast, frequent inactivation mutations of SETDB1 have been revealed in mesothelioma, an asbestos-associated, locally aggressive, highly lethal, and notoriously chemotherapy-resistant cancer. Above all, the different statuses of SETDB1 indicate that it may have different biological functions and be a potential diagnostic biomarker and therapeutic target in lung cancer and mesothelioma.

Multi-Omics Analysis Showed the Clinical Value of Gene Signatures of C1QC+ and SPP1+ TAMs in Cervical Cancer

Purpose

To evaluate the value of C1QC⁺ and SPP1⁺ TAMs gene signatures in patients with cervical cancer.

Methods

We compare the C1QC⁺ and SPP1⁺ TAMs gene signatures with the M1/M2 gene signatures at single cell level and bulk RNA-seq level and evaluate which gene signature can clearly divide TAMs and patients with cervical cancer into distinct clinical subclusters better.

Results

At single-cell level, C1QC⁺ and SPP1⁺ TAMs gene signatures, but not M1 and M2 gene signatures, could clearly divided TAMs into two subclusters in a colon cancer data set and an advanced basal cell data set. For cervical cancer data from TCGA, patients with C1QC^high and SPP1^low TAMs gene signatures have the best prognosis, lowest proportion (34.21%) of locally advanced cervical cancer (LACC), and highest immune cell infiltration, whereas patients with C1QC^low and SPP1^high TAMs gene signatures have the worst prognosis, highest proportion (71.79%) of LACC and lowest immune cell infiltration. Patients with C1QC^high and SPP1^low TAMs gene signature have higher expression of most of the Immune checkpoint molecules (ICMs) than patients with C1QC^low and SPP1^high TAMs gene signatures. The GSEA results suggested that subgroups of patients divided by C1QC⁺ and SPP1⁺ TAMs gene signatures showed different anti- or pro-tumor state.

Conclusion

C1QC⁺ and SPP1⁺ TAMs gene signatures, but not M1/M2 gene signatures, can divide cervical patients into subgroups with different prognosis, tumor stage, different immune cell infiltration, and ICMs expression. Our findings may help to find suitable treatment strategy for cervical cancer patients with different TAMs gene signatures.

The emerging landscape of immune checkpoint inhibitor based clinical trials in adults with advanced rare tumors

"Rare cancers" are a diverse collection of cancers that collectively account for approximately 20% of all adult cancers in the United States. Their rarity has caused an underrepresentation of these cancers in preclinical research and clinical trials, leading to fewer (and often no) treatment options for patients backed by robust clinical evidence. The recent advent of immune checkpoint inhibitors (ICIs) into the oncologist's armamentarium, while revolutionizing the treatment of many common cancers, has also started to make gradual inroads into the treatment of certain rare cancers. One reason is that the efficacy of ICIs depends more on factors intrinsic to the tumor cells and the tumor microenvironment and less on tumor histology. Recent years have seen ICI approvals in many rare cancers, and many trials are being designed using ICIs as single agents or in combination. In this commentary, we present an overview of the emerging role of ICIs in some rare cancers.

Enhanced efficacy of mesothelin-targeted immunotoxin LMB-100 and anti-PD-1 antibody in patients with mesothelioma and mouse tumor models

LMB-100 is an immunotoxin targeting the cell surface protein mesothelin, which is highly expressed in many cancers including mesothelioma. Having observed that patients receiving pembrolizumab off protocol after LMB-100 treatment had increased tumor responses; we characterized these responses and developed animal models to study whether LMB-100 made tumors more responsive to antibodies blocking programmed cell death protein 1 (PD-1). The overall objective tumor response in the 10 patients who received PD-1 inhibitor (pembrolizumab, 9; nivolumab, 1) after progression on LMB-100 was 40%, and the median overall survival was 11.9 months. Of the seven evaluable patients, four had objective tumor responses, including one complete response and three partial responses, and the overall survival for these patients was 39.0+, 27.7, 32.6+, and 13.8 months. When stratified with regard to programmed death ligand 1 (PD-L1) expression, four of five patients with tumor PD-L1 expression had objective tumor response. Patients with positive tumor PD-L1 expression also had increased progression-free survival (11.3 versus 2.1 months, P = 0.0018) compared with those lacking PD-L1 expression. There was no statistically significant difference in overall survival (27.7 versus 6.8 months, P = 0.1). LMB-100 caused a systemic inflammatory response and recruitment of CD8⁺ T cells in patients' tumors. The enhanced antitumor effects with LMB-100 plus anti-PD-1 antibody were also observed in a human peripheral blood mononuclear cell-engrafted mesothelioma mouse model and a human mesothelin-expressing syngeneic lung adenocarcinoma mouse model. LMB-100 plus pembrolizumab is now being evaluated in a prospective clinical trial for patients with mesothelioma.

ERS/ESTS/EACTS/ESTRO guidelines for the management of malignant pleural mesothelioma

The European Respiratory Society (ERS)/European Society of Thoracic Surgeons (ESTS)/European Association for Cardio-Thoracic Surgery (EACTS)/European Society for Radiotherapy and Oncology (ESTRO) task force brought together experts to update previous 2009 ERS/ESTS guidelines on management of malignant pleural mesothelioma (MPM), a rare cancer with globally poor outcome, after a systematic review of the 2009-2018 literature. The evidence was appraised using the Grading of Recommendations, Assessment, Development and Evaluation approach. The evidence syntheses were discussed and recommendations formulated by this multidisciplinary group of experts. Diagnosis: pleural biopsies remain the gold standard to confirm the diagnosis, usually obtained by thoracoscopy but occasionally via image-guided percutaneous needle biopsy in cases of pleural symphysis or poor performance status. Pathology: standard staining procedures are insufficient in ∼10% of cases, justifying the use of specific markers, including BAP-1 and CDKN2A (p16) for the separation of atypical mesothelial proliferation from MPM. Staging: in the absence of a uniform, robust and validated staging system, we advise using the most recent 2016 8th TNM (tumour, node, metastasis) classification, with an algorithm for pretherapeutic assessment. Monitoring: patient's performance status, histological subtype and tumour volume are the main prognostic factors of clinical importance in routine MPM management. Other potential parameters should be recorded at baseline and reported in clinical trials. Treatment: (chemo)therapy has limited efficacy in MPM patients and only selected patients are candidates for radical surgery. New promising targeted therapies, immunotherapies and strategies have been reviewed. Because of limited data on the best combination treatment, we emphasize that patients who are considered candidates for a multimodal approach, including radical surgery, should be treated as part of clinical trials in MPM-dedicated centres.

[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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Levels of Circulating PD-L1 Are Decreased in Patients with Resectable Cholangiocarcinoma

Tumor resection represents the only curative treatment option for patients with biliary tract cancers (BTCs), including intrahepatic cholangiocarcinoma (CCA), perihilar and extrahepatic CCA and gallbladder cancer. However, many patients develop early tumor recurrence and are unlikely to benefit from surgery. Therefore, markers to identify ideal surgical candidates are urgently needed. Circulating programmed cell death 1 ligand 1 (PD-L1) has recently been associated with different malignancies, including pancreatic cancer which closely resembles BTC in terms of patients’ prognosis and tumor biology. Here, we aim at evaluating a potential role of circulating PD-L1 as a novel biomarker for resectable BTC. Methods: Serum levels of PD-L1 were analyzed by ELISA in 73 BTC patients and 42 healthy controls. Results: Circulating levels of preoperative PD-L1 were significantly lower in patients with BTC compared to controls. Patients with low PD-L1 levels displayed a strong trend towards an impaired prognosis, and circulating PD-L1 was negatively correlated with experimental markers of promalignant tumor characteristics such as CCL1, CCL21, CCL25 and CCL26. For 37 out of 73 patients, postoperative PD-L1 levels were available. Interestingly, after tumor resection, circulating PD-L1 raised to almost normal levels. Notably, patients with further decreasing PD-L1 concentrations after surgery showed a trend towards an impaired postoperative outcome. Conclusion: Circulating PD-L1 levels were decreased in patients with resectable BTC. Lack of normalization of PD-L1 levels after surgery might identify patients at high risk for tumor recurrence or adverse outcome.

Immune checkpoint inhibitors a new player in the therapeutic game of mesothelioma: New reality with new challenges

Malignant pleural mesothelioma (MPM) is a rare and orphan thoracic malignancy, with a poor prognosis as the majority of patients are diagnosed with unresectable MPM, with no significant improvements in the therapeutic strategy for over a decade. However, the recent approval of immune checkpoint inhibitors (ICI) in treatment-naïve patients with unresectable MPM marks a significant step forward and hope for the treatment of this disease. In this narrative review, we discuss the biological rationale to use ICI in the treatment of MPM. We summarize the current evidence for the efficacy of ICI in MPM and discuss several unresolved challenges regarding the use of ICI in this disease, such as the best upfront immune approach in MPM (ICI versus ICI plus chemotherapy), the optimal sequential treatment strategy according to the first-line treatment, and the potential role of predictive biomarkers.

Immune Checkpoint Inhibition for Unresectable Malignant Pleural Mesothelioma

Immune checkpoint inhibitors (ICI) have shown important but variable efficacy in mesothelioma despite a lack of strong biological rationale. Initial trials assessed ICI monotherapy in patients with relapsed mesothelioma, with objective response rates (ORR) between 4.5 and 29%, median progression-free survival (PFS) between 2.5-6.2 months, and median overall survival (OS) between 7.7 and 18.0 months. In randomised trials of chemotherapy pre-treated patients, nivolumab was recently shown to improve PFS compared to placebo, but tremelimumab was not superior to placebo, and there was no difference in OS between pembrolizumab and chemotherapy. However, response to combination ICI appear more promising in both pre-treated and treatment-naïve mesothelioma. The randomised Phase 3 trial of upfront ipilimumab-nivolumab versus platinum-pemetrexed chemotherapy demonstrated improved OS favouring ipilimumab-nivolumab (HR 0.74, 96.6% CI 0.60-0.91; p = 0.0020), establishing this regimen as a new standard of care, especially in non-epithelioid histological subtypes. However, initially PFS was poorer in the ipilimumab-nivolumab than chemotherapy treatment arms. A single-arm Phase 2 trial of upfront platinum chemotherapy and durvalumab met its primary endpoint, with a 6-month PFS of 57% (95% CI 44-70) with chemo-immunotherapy under evaluation as an alternative upfront regimen. Several questions remain unanswered. Comparative studies of chemo-immunotherapy versus chemotherapy are underway, but these do not compare chemo-immunotherapy to combination ICI. There is a critical need to establish predictive biomarkers to improve patient selection. As ICI use moves into the front-line setting, patient selection, role for operable patients, and understanding ICI resistance mechanisms alongside role of ICI rechallenge in previous responders need further evaluation.

Immunotherapeutic Approaches in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and aggressive malignant disease affecting the mesothelium, commonly associated to asbestos exposure. The current therapeutic actions, based on cisplatin/pemetrexed treatment, are limited due to the late stage at which most patients are diagnosed and to the intrinsic chemo-resistance of the tumor. Another relevant point is the absence of approved therapies in the second line setting following progression of MPM after chemotherapy. Considering the poor prognosis of the disease and the fact that the incidence of this tumor is expected to increase in the next decade, novel therapeutic approaches are urgently needed. In the last few years, several studies have investigated the efficacy and safety of immune-checkpoint inhibitors (ICIs) in the treatment of unresectable advanced MPM, and a number of trials with immunotherapeutic agents are ongoing in both first line and second line settings. In this review, we describe the most promising emerging immunotherapy treatments for MPM (ICIs, engineered T cells to express chimeric antigen receptors (CARs), dendritic cells (DCs) vaccines), focusing on the biological and immunological features of this tumor as well as on the issues surrounding clinical trial design.