Efficacy and safety of an intensified schedule of tremelimumab for chemotherapy-resistant malignant mesothelioma: an open-label, single-arm, phase 2 study

A comprehensive review of immune checkpoint inhibitors for cancer treatment

Immunology-based therapies are emerging as an effective cancer treatment, using the body's immune system to target tumors. Immune checkpoints, which regulate immune responses to prevent tissue damage and autoimmunity, are often exploited by cancer cells to avoid destruction. The discovery of checkpoint proteins like PD-1/PD-L1 and CTLA-4 was pivotal in developing cancer immunotherapy. Immune checkpoint inhibitors (ICIs) have shown great success, with FDA-approved drugs like PD-1 inhibitors (Nivolumab, Pembrolizumab, Cemiplimab), PD-L1 inhibitors (Atezolizumab, Durvalumab, Avelumab), and CTLA-4 inhibitors (Ipilimumab, Tremelimumab), alongside LAG-3 inhibitor Relatlimab. Research continues on new checkpoints like TIM-3, VISTA, B7-H3, BTLA, and TIGIT. Biomarkers like PDL-1 expression, tumor mutation burden, interferon-γ presence, microbiome composition, and extracellular matrix characteristics play a crucial role in predicting responses to immunotherapy with checkpoint inhibitors. Despite their effectiveness, not all patients experience the same level of benefit, and organ-specific immune-related adverse events (irAEs) such as rash or itching, colitis, diarrhea, hyperthyroidism, and hypothyroidism may occur. Given the rapid advancements in this field and the variability in patient outcomes, there is an urgent need for a comprehensive review that consolidates the latest findings on immune checkpoint inhibitors, covering their clinical status, biomarkers, resistance mechanisms, strategies to overcome resistance, and associated adverse effects. This review aims to fill this gap by providing an analysis of the current clinical status of ICIs, emerging biomarkers, mechanisms of resistance, strategies to enhance therapeutic efficacy, and assessment of adverse effects. This review is crucial to furthering our understanding of ICIs and optimizing their application in cancer therapy.

Immunotherapy for Treatment of Pleural Mesothelioma: Current and Emerging Therapeutic Strategies

Pleural mesothelioma is a rare malignancy associated with asbestos exposure and very poor prognosis, with a 5-year overall survival of 12%. Outcomes may vary according to stage at time of diagnosis and histologic subtype. Most recently, clinical trials utilizing dual checkpoint inhibitor regimens and chemotherapy in combination with immune oncologic agents have demonstrated impactful changes in outcomes. In this article, we review studies that have led to the successful implementation of immunotherapy in clinical practice for the treatment of this disease and highlight ongoing clinical trials exploring the use of different immunotherapy strategies for the treatment of pleural mesothelioma. We also discuss the challenges of immunotherapy-based approaches in the context of mesothelioma and future strategies currently being investigated to overcome them.

Advances in Immunotherapy for Malignant Pleural Mesothelioma: From Emerging Strategies to Translational Insights

MPM stands as a rare malignancy necessitating improved therapeutic strategies due to its limited treatment choices and unfavorable prognosis. The advent of immune checkpoint inhibitors has heralded a paradigm shift in the therapeutic landscape of MPM, offering promising avenues across diverse clinical scenarios. In the context of advanced stages of the disease, Immune check-point inhibitors targeting programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-as-sociated protein 4 (CTLA-4), have exhibited encouraging potential in clinical trials, particularly manifesting efficacy among patients exhibiting disease progression following chemotherapy regimens. Innovative combination regimens, exemplified by the concurrent administration of nivolumab and ipilimumab, have demonstrated marked improvement in survival and patient's benefits. A deeper comprehension of the intricate genetic underpinnings of MPM, encompassing key mutations such as cyclin-dependent kinase inhibitor 2A (CDKN2A), neurofibromin 2 (NF2), and BRCA1-associated protein 1 (BAP1) mutations, has elucidated novel avenues for targeted therapeutic interventions. This review accentuates the transformative capacity of immunotherapy in revolutionizing the therapeutic outlook for MPM, thereby potentially translating into augmented survival rates and offering glimpses of new approaches on the horizon. Despite the persisting challenges, the synergistic crossroads of interdisciplinary research and collaborative clinical endeavors portend a hopeful landscape for MPM treatment.

INDUCE-2: A Phase I/II, open-label, two-part study of feladilimab in combination with tremelimumab in patients with advanced solid tumors

Combining immunotherapies with distinct mechanisms of action has the potential to overcome treatment resistance and improve outcomes. The inducible T-cell co-stimulator (ICOS) agonist feladilimab is directed at enhancing T-cell activation and function, thereby promoting an antitumor response. INDUCE-2 (NCT03693612) was a Phase I/II, open-label, two-part study evaluating the anti-ICOS agonist feladilimab in combination with the anti-CTLA-4 antibody tremelimumab in patients with select advanced solid tumors. Objectives of Part 1 were to determine the safety, tolerability, and recommended phase 2 dose (RP2D) of feladilimab in combination with tremelimumab. In Part 2, the antitumor activity of the combination (administered at the RP2D determined in Part 1) was to be assessed in patients with relapsed/refractory head and neck squamous cell carcinoma. Primary endpoints included the rates of dose-limiting toxicities (DLTs), adverse events (AEs), AEs of special interest, and serious AEs. Secondary endpoints included overall response rate, while biomarker assessment was exploratory. A total of 26 patients were enrolled, 18 (69%) of whom had completed the study at end date. One patient, in the highest dose group (24/225 mg feladilimab/tremelimumab), experienced a DLT 18 days after the first dose of study treatment. All patients experienced at least one AE; AEs led to treatment discontinuation in four (15%) patients. Partial response was observed in one patient. Feladilimab in combination with tremelimumab was well-tolerated but showed limited efficacy. Based on the totality of data from Part 1, it was decided not to continue with Part 2.

Unveiling the mechanisms and challenges of cancer drug resistance

Cancer treatment faces many hurdles and resistance is one among them. Anti-cancer treatment strategies are evolving due to innate and acquired resistance capacity, governed by genetic, epigenetic, proteomic, metabolic, or microenvironmental cues that ultimately enable selected cancer cells to survive and progress under unfavorable conditions. Although the mechanism of drug resistance is being widely studied to generate new target-based drugs with better potency than existing ones. However, due to the broader flexibility in acquired drug resistance, advanced therapeutic options with better efficacy need to be explored. Combination therapy is an alternative with a better success rate though the risk of amplified side effects is commonplace. Moreover, recent groundbreaking precision immune therapy is one of the ways to overcome drug resistance and has revolutionized anticancer therapy to a greater extent with the only limitation of being individual-specific and needs further attention. This review will focus on the challenges and strategies opted by cancer cells to withstand the current therapies at the molecular level and also highlights the emerging therapeutic options -like immunological, and stem cell-based options that may prove to have better potential to challenge the existing problem of therapy resistance. Video Abstract.

The future of targeting cytotoxic T-lymphocyte-associated protein-4: Is there a role?

The 2022 yearly Think Tank Meeting in Siena, Tuscany (Italy), organized by the Italian Network for Tumor Biotherapy (NIBIT) Foundation, the Parker Institute for Cancer Immunotherapy and the World Immunotherapy Council, included a focus on the future of integrating and expanding the use of targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). The conference members exchanged their views on the lessons from targeting CTLA-4 and compared the effect to the impact of blocking Programmed cell death protein 1 (PD1) or its ligand (PDL1). The increasing experience with both therapeutic approaches and their combination suggests that targeting CTLA-4 may lead to more durable responses for a sizeable proportion of patients, though the specific mechanism is not entirely understood. Overcoming toxicity of blocking CTLA-4 is currently being addressed with different doses and dose regimens, especially when combined with PD1/PDL1 blocking antibodies. Novel therapeutics targeting CTLA-4 hold the promise to reduce toxicities and thus allow different combination strategies in the future. On the whole, the consent was that targeting CTLA-4 remains an important strategy to improve the efficacy of cancer immunotherapies.

Immunotherapy of mesothelioma: the evolving change of a long-standing therapeutic dream

Pleural mesothelioma (PM) is an aggressive and rare disease, characterized by a very poor prognosis. For almost two decades, the world standard treatment regimen for unresectable PM has consisted of a platinum-based drug plus pemetrexed, leading to an overall survival of approximately 12 months. The dramatic therapeutic scenario of PM has recently changed with the entry into the clinic of immune checkpoint inhibition, which has proven to be an effective approach to improve the survival of PM patients. The aim of the present review is to provide a comprehensive overview of the most promising immunotherapeutic-based strategies currently under investigation for advanced PM.

Updates in Management of Malignant Pleural Mesothelioma

OPINION STATEMENT

Malignant pleural mesothelioma (MPM) is an aggressive asbestos-associated thoracic malignancy that is usually incurable. As demonstrated in the landmark MARS2 trial, surgical resection does not improve survival outcomes and its role in managing MPM is limited. Whilst platinum-pemetrexed chemotherapy in combination with bevacizumab was the standard first-line approach for unresectable disease, landmark phase 3 trials have now established the role of immune checkpoint inhibitors (CPIs) in the upfront management of unresectable disease: either nivolumab-ipilimumab or carboplatin-pemetrexed-pembrolizumab. Patient selection for optimal strategy remains an ongoing question. For relapsed disease novel genomic-based therapies targeting a range of aberrations including losses of the tumour suppressor genes BAP1, CDKN2A and NF2, are being evaluated. Nonetheless, the future of MPM therapeutics holds promise. Here we overview current treatment strategies in the management of MPM.

Akkermansia muciniphila: a potential booster to improve the effectiveness of cancer immunotherapy

Cancer immunotherapy has emerged as a groundbreaking method of treating malignancies. However, cancer immunotherapy can only benefit a small percentage of patients, and the numerous side effects that might develop during treatment reduce its effectiveness or even put patients' lives in jeopardy. Surprisingly, the gut microbiome Akkermansia muciniphila (A. muciniphila) can significantly inhibit carcinogenesis and improve anti-tumor effects, thus increasing the effectiveness of cancer immunotherapy and decreasing the likelihood of side effects. In this review, we focus on the effects of A. muciniphila on the human immune system and the positive impacts of A. muciniphila on cancer immunotherapy, which can build on strengths and improve weaknesses of cancer immunotherapy. The potential clinical applications of A. muciniphila on cancer immunotherapy are also proposed, which have great prospects for anti-tumor therapy.

Malignant Peritoneal Mesothelioma: An In-Depth and Up-to-Date Review of Pathogenesis, Diagnosis, Management and Future Directions

Malignant peritoneal mesothelioma (MPM) is an extremely rare malignancy usually confined to the abdominal cavity. With an aggressive natural history, morbidity and mortality are consequences of progressive locoregional effects within the peritoneal cavity. The first reported case was in the early 20th century, however, due to the rare nature of the disease and a large gap in understanding of the clinicopathological effects, the next reported MPM cases were only published half a decade later. Since then, there has been exponential growth in our understanding of the disease, however, there are no prospective data and a paucity of literature regarding management. Traditionally, patients were treated with systemic therapy and the outcomes were very poor, with a median survival of less than one year. However, with the advent of cytoreductive surgery and locoregional chemotherapy, there have been significant improvements in survival. Even more recently, with an improved understanding of the molecular pathogenesis of MPM, there have been reports of improved outcomes with novel therapies. Given the disastrous natural history of MPM, the limited data, and the lack of universal treatment guidelines, an in-depth review of the past, present, and future of MPM is critical to improve treatment regimens and, subsequently, patient outcomes.

Improvements in Systemic Therapies for Advanced Malignant Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and aggressive malignancy associated with poor prognosis and a 5-year survival rate of 12%. Many drugs have been tested over the years with conflicting results. The aim of this review is to provide an overview of current therapies in MPM and how to best interpret the data available on these drugs. Furthermore, we focused on promising treatments under investigation, such as immunotherapy with targets different from anti-PD-1/PD-L1 inhibitors, vaccines, target therapies, and metabolism-based strategies.

Immunotherapy vs. Chemotherapy in Subsequent Treatment of Malignant Pleural Mesothelioma: Which Is Better?

(1) Background: Malignant pleural mesothelioma (MPM) is a rare but aggressive tumor arising from the pleural surface. For relapsed MPM, there is no accepted standard of- are for subsequent treatment. Thus, we aimed to compare the efficacy of chemotherapy, targeting drugs, and immune-checkpoint inhibitors (ICIs) as subsequent therapy for relapsed MPM. (2) Methods: The study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We searched several acknowledged databases. Primary outcomes were defined as overall median progressive survival (mPFS) and median overall survival (mOS) in different treatment groups. Secondary outcomes were defined as objective response rate (ORR), the proportion of stable disease (SD), and progressive disease (PD). (3) Results: Ultimately, 43 articles were selected for the meta-analysis. According to the results of a pooled analysis of single-arm studies, ICIs showed a slight advantage in mOS, while chemotherapy showed a slight advantage in mPFS (mOS: 11.2 m vs. 10.39 m and mPFS: 4.42 m vs. 5.08 m for ICIs group and chemotherapy group, respectively). We identified only a few studies that directly compared the efficacy of ICIs with that of chemotherapy, and ICIs did not show significant benefits over chemotherapy based on mOS. (4) Conclusions: Based on current evidence, we considered that immunotherapy might not be superior to chemotherapy as a subsequent therapy for relapsed MPM. Although several studies investigated the efficacy of ICIs, targeting drugs, and chemotherapy in relapsed MPM, there was still no standard of care. Further randomized control trials with consistent criteria and outcomes are recommended to guide subsequent therapy in relapsed MPM and identify patients with certain characteristics that might benefit from such subsequent therapy.

Genomic and transcriptomic analyses identify a prognostic gene signature and predict response to therapy in pleural and peritoneal mesothelioma

Malignant mesothelioma is an aggressive cancer with limited treatment options and poor prognosis. A better understanding of mesothelioma genomics and transcriptomics could advance therapies. Here, we present a mesothelioma cohort of 122 patients along with their germline and tumor whole-exome and tumor RNA sequencing data as well as phenotypic and drug response information. We identify a 48-gene prognostic signature that is highly predictive of mesothelioma patient survival, including CCNB1, the expression of which is highly predictive of patient survival on its own. In addition, we analyze the transcriptomics data to study the tumor immune microenvironment and identify synthetic-lethality-based signatures predictive of response to therapy. This germline and somatic whole-exome sequencing as well as transcriptomics data from the same patient are a valuable resource to address important biological questions, including prognostic biomarkers and determinants of treatment response in mesothelioma.

Immunotherapies in rare cancers

Cancer remains a leading cause of death worldwide, placing a significant burden on healthcare systems as well as the global economy. Rare cancers comprise a group of about 200 cancers that individually occur at extremely low frequencies. In the United States (US), their frequency is approximately 15 cases per 100,000 people, and it is even lower in Europe with approximately 6 cases per 100,000 people. However, combined their frequency of occurrence is much higher than any singular cancer. Cancer treatment and management has tremendously improved in the last decade, particularly with the administration of immune-based therapies. The four most prevalent immune-based therapies are (1) the use of immune-checkpoint inhibitors, (2) macrophage therapy, (3) Chimeric Antigen Receptor (CAR) T cell therapy, and (4) neoantigen-based therapies. In our review, we discuss these various aproaches and their implementation in the treatment of a variety of rare cancers. Furthermore, we discuss their limitations and potential strategies to overcome them to enhance the therapeutic efficacy of these approaches. Finally, our article presents the future directions and other additional immune therapies that may be incorporated into the treatment of rare cancers.

Characterization of the high-affinity anti-CTLA-4 monoclonal antibody JS007 for immune checkpoint therapy of cancer

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is a critical inhibitory checkpoint molecule, and monoclonal antibodies (mAbs) targeting CTLA-4 that restore anti-tumor T cell immunity have achieved clinical success. Here, we report a humanized IgG1 mAb, namely JS007, with high binding affinity to CTLA-4. JS007 shows superior binding affinity and T-cell activating efficiency over ipilimumab. Moreover, it demonstrates substantial in vivo tumor suppression efficacy at low doses. The crystal structure of JS007/CTLA-4 complex (PDB: 8HIT) shows JS007 adopts a heavy-chain-dominant binding mode, and mainly contacts the BC loop, DE loop and FG loop of CTLA-4. Notably, two Tyr residues (VH-Y100 and VL-Y32) from the complementarity-determining region loops insert into the two cavities formed by the residues from the loops of CTLA-4, which may contribute to the stabilization of the binding. Comparative analysis with other anti-CTLA-4 mAbs indicates that the double "wedge-into-hole" binding mode is unique for JS007 and may be responsible for the high-affinity binding to CTLA-4. These findings have provided an important molecular understanding of the high-affinity CTLA-4 blockade mAbs and shed light on future development of agents targeting CTLA-4.

Immune Checkpoint Inhibitors in Malignant Pleural Mesothelioma: A Systematic Review and Meta-Analysis

Many clinical trials have investigated the role of ICIs in PM, with contrasting results. We performed a systematic review and meta-analysis of clinical trials testing single-agent anti-Programmed Death -1 (PD-1)/Programmed Death-Ligand 1 (PD-L1), anti-Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4) or combined treatment in PM patients, analyzing response and survival rate as well as safety data. We selected 17 studies including 2328 patients. Both OS and PFS rates were significantly higher with combined ICI treatments than with single agent anti-PD-1/PD-L1 (p < 0.001 and p = 0.006, respectively) or anti CTLA-4 (p < 0.001) treatments. ORR and DCR for all ICI treatments were 20% (95% CI 13−27%) and 56% (95% CI 45−67%), respectively, and they did not significantly differ between combined and single agent treatments (p = 0.088 and p = 0.058, respectively). The 12-month OS and 6-month PFS rates did not differ significantly (p = 0.0545 and p = 0.1464, respectively) among pre-treated or untreated patients. Combined ICI treatments had a significantly higher rate of Adverse Events (AEs) (p = 0.01). PD-L1-positive patients had a higher probability of response and survival. In conclusion, combined ICI treatments have higher efficacy than single agents but are limited by higher toxicity. Efficacy was independent of treatment line, so a customized sequential strategy should still be speculated. PD-L1 expression could influence response to ICIs; however, reliable biomarkers are warranted.

Protocol for a prospective observational cohort study collecting data on demographics, symptoms and biomarkers in people with mesothelioma (ASSESS-meso)

INTRODUCTION

Mesothelioma is a heterogeneous disease that can be challenging to monitor and prognosticate. ASSESS-meso is a multicentre, prospective, longitudinal observational cohort study of patients with mesothelioma. The primary aim is to describe different clinical phenotypes and investigate predictive and prognostic factors, including biomarkers from blood and pleural fluid. The secondary aim is to provide a resource for future trials and substudies.

METHODS AND ANALYSIS

We aim to recruit 700 patients with a histological, cytological or clinicopathological diagnosis of mesothelioma, at any anatomical site (pleural, peritoneal, pericardial, etc). Longitudinal data will be collected, including clinical information, radiological investigations, blood tests and patient-reported outcome measures for breathlessness, chest pain and sweats. Preplanned analyses will use Cox proportional hazards method to evaluate factors associated with survival, linear and logistic regression models to investigate associations with symptoms, and analysis of variance modelling to explore changes in symptoms over time.

ETHICS AND DISSEMINATION

Ethical approval has been granted by the Research Ethics Committee South West-Central Bristol (17-SW-0019) and Health Research Authority (IRAS ID 220360). A study steering committee has been established and results will be published OpenAccess in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ISRCTN: 61861764.

Malignant peritoneal mesothelioma with massive ascites as the first symptom: A case report

BACKGROUND

Malignant peritoneal mesothelioma (MPM) is an extremely rare tumor with nonspecific clinical manifestations, which is extremely difficult to diagnose. Herein, we reported a case of MPM in the abdominal cavity with massive short-term ascites as the first symptom.

CASE SUMMARY

A 65-year-old woman presented to the hospital with abdominal pain, distention, and shortness of breath that persisted for 15 d. The serum CA-125 level was 1075 U/mL. The abdominal computed tomography showed massive ascites and no obvious tumor lesions. The pathological examination of the ascitic fluid showed numerous heterotypic cells with some papillary structures. The immunohistochemistry and fluorescence in situ hybridization showed the deletion of CDX2 (-), WT-1 (-), Ki-67 (about 10% +), CEA (-), Glut-1 (+++), desmin (-), PD-L1 (-), and CDKN2A (P16). The final diagnosis was MPM. The patient refused tumor cytoreductive surgery and received two cycles of cisplatin plus pemetrexed bidirectional chemotherapy. In the second cycle, she received an additional cycle of hyperthermic intraperitoneal chemotherapy and immune checkpoint inhibitor therapy due to massive recalcitrant ascites. She died of disease progression 2 mo after diagnosis.

CONCLUSION

In case of massive unexplained ascites, the possibility of MPM should not be excluded to avoid misdiagnosis and delay in treatment.

Deciphering Prognostic Value of TTN and Its Correlation With Immune Infiltration in Lung Adenocarcinoma

Background

Lung adenocarcinoma (LUAD) is the most common type of lung cancer, accounting for around 40%. Despite achievements in the treatment approach, the prognosis is still dismal, with overall survival of fewer than five years. Thus, novel prognostic biomarkers are needed to predict the clinical outcomes of individual patients better. TTN has a high mutation rate in the LUAD, which encodes a large abundant protein of striated muscle. However, the value of TTN in prognosis and the immune environment are poorly understood.

Methods

We investigated the clinicopathological characteristics, transcriptional and protein level, prognostic value, biological function, and its relationship with immune infiltration of TTN gene in LUAD patients through bioinformatics analysis.

Results

TTN expression was significantly lower in LUAD than that in normal lung tissue. Lower TTN expression was associated with worse survival. Besides, TTN is highly expressed in alveolar type 2 cells which were surmised as the origin of LUAD.

Conclusion

Our findings indicated the potential prognostic value of TTN and its role as a biomarker for determining the immune infiltration levels in patients with LUAD.

Appropriate Supervised Machine Learning Techniques for Mesothelioma Detection and Cure

Mesothelioma is a dangerous, violent cancer, which forms a protecting layer around inner tissues such as the lungs, stomach, and heart. We investigate numerous AI methodologies and consider the exact DM conclusion outcomes in this study, which focuses on DM determination. K-nearest neighborhood, linear-discriminant analysis, Naive Bayes, decision-tree, random forest, support vector machine, and logistic regression analyses have been used in clinical decision support systems in the detection of mesothelioma. To test the accuracy of the evaluated categorizers, the researchers used a dataset of 350 instances with 35 highlights and six execution measures. LDA, NB, KNN, SVM, DT, LogR, and RF have precisions of 65%, 70%, 92%, 100%, 100%, 100%, and 100%, correspondingly. In count, the calculated complication of individual approaches has been evaluated. Every process is chosen on the basis of its characterization, exactness, and calculated complications. SVM, DT, LogR, and RF outclass the others and, unexpectedly, earlier research.

Current status and progress in immunotherapy for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and aggressive malignant disease. Currently, the platinum doublet of pemetrexed and cisplatin is the standard first-line treatment for unresectable MPM. However, recent promising results of immunotherapy have markedly changed the landscape of MPM treatment. Further, the ongoing innovative therapeutic strategies are expected to expand the range of treatment options; however, several questions remain unanswered. First, establishing predictive biomarkers with high potency is urgently needed to optimize the patient selection process. Second, further exploration of the combination algorithm is expected to unveil more effective and safe regimens. Moreover, other dilemmas, such as the resistance mechanism of immunotherapy and the role of immunotherapy in perioperative settings, still warrant further exploration.

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.

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.

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.

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.

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.

Efficacy of Immune Checkpoint Inhibitors in Rare Tumours: A Systematic Review

Background

Rare cancers, as defined by the European Union, occur in fewer than 15 out of 100,000 people each year. The International Rare Cancer Consortium defines rare cancer incidence as less than six per 100,000 per year. There is a growing number of reports of the efficacy of immune checkpoint inhibitor (ICI) therapy in patients with rare tumours, and hence, we conducted a comprehensive review to summarise and analyse the available literature.

Methods

A literature search of PubMed was performed on January 31, 2021, using the following ICI names as keywords: ipilimumab, tremelimumab, cemiplimab, nivolumab, pembrolizumab, avelumab, atezolizumab, and durvalumab. Studies on patients with rare tumours who were being treated with ICIs were included. We plotted the overall response rate against the corresponding median survival across a variety of cancer types using linear regression.

Results

From 1,255 publications retrieved during the primary search, 62 publications were selected (with a total of 4,620 patients). Only four were randomised trials. A minority were first-line studies, while the remaining were studies in which ICIs were delivered as salvage therapy in pretreated patients. There was a good correlation between response rate and overall survival (Spearman R2 >0.9) in skin cancers, mesothelioma, and sarcomas.

Conclusions

Treatment of advanced-stage rare tumours with ICI therapy was found to be associated with significant activity in some orphan diseases (e.g., Merkel cell carcinoma) and hepatocellular carcinoma. Several ongoing prospective clinical trials will expand the knowledge on the safety and efficacy of ICI therapy in patients with these rare cancers.

Tremelimumab plus durvalumab retreatment and 4-year outcomes in patients with mesothelioma: a follow-up of the open label, non-randomised, phase 2 NIBIT-MESO-1 study

BACKGROUND

The NIBIT-MESO-1 study demonstrated the efficacy and safety of tremelimumab combined with durvalumab in patient with unresectable mesothelioma followed up for a median of 52 months [IQR 49-53]. Here, we report 4-year survival and outcomes after retreatment, and the role of tumour mutational burden (TMB) in identifying patients who might have a better outcome in response to combined therapy.

METHODS

NIBIT-MESO-1 was an open-label, non-randomised, phase 2 trial of patients with unresectable pleural or peritoneal mesothelioma who received intravenous tremelimumab (1 mg/kg bodyweight) and durvalumab (20 mg/kg bodyweight) every 4 weeks for four doses, followed by maintenance intravenous durvalumab at the same dose and schedule for nine doses. In this follow-up study, patients with disease progression following initial clinical benefit-ie, a partial repsonse or stable disease-were eligible for retreatment and with the same doses and schedules for tremelimumab and durvalumab as used in the NIBIT-MESO-1 trial. The primary endpoint, immune-related objective response rate, was evaluated per immune-related modified Response Evaluation Criteria in Solid Tumors (RECIST) or immune-related RECIST 1.1 criteria for patients with pleural or peritoneal malignant mesothelioma, respectively. Key secondary endpoints were overall survival and safety, and TMB was also evaluated post hoc in patients who had tumour tissue available before treatment. The intention-to-treat population was used for analysis of all efficacy endpoints. This study is registered with ClinicalTrials.gov, number NCT02588131.

FINDINGS

40 patients were enrolled in the NIBIT-MESO-1 study between Oct 30, 2015, and Oct 12, 2016. At data cut-off, April 30, 2020, five (13%) of 40 patients were alive, and 35 (88%) patients had died of progressive disease. At a median follow-up of 52 months (IQR 49-53), median overall survival was 16·5 months (95% CI 13·7-19·2). Survival was 20% (eight of 40 patients) at 36 months and 15% (six of 40 patients) and 48 months. 17 (43%) of 40 patients met the criteria for enrolment in the retreatment study and were retreated with at least one dose of tremelimumab and durvalumab. No immune-related objective responses were observed in the 17 retreated patients. Seven (41%) of 17 patients achieved immune-related stable disease. From the start of retreatment to a median follow-up of 24 months (22·0-25·0), median overall survival was 12·5 months (95% CI 0·0-25·8), and survival at 12 months was 52·9%, at 18 months was 35·3%, and at 24 months was 23·5%. There were no grade 3-4 immune-related adverse events in the retreatment cohort. In a post-hoc analysis of 28 patients for whom tumour tissue before treatment was available, patients with a TMB higher than the median value of 8·3 mutations per Mb had a higher median overall survival compared with patients with TMB below the median value, but this difference was non-significant. Moreover, when patients were additionally stratified for ICI retreatment (n=13), there was a significant difference in survival between those with a TMB higher than the median of 8·3 mutations per Mb and those with TMB lower than the median in the retreated cohort (41·3 months vs 17·4 months; p=0·02).

INTERPRETATION

Tremelimumab combined with durvalumab was associated with long-term survival in patients with mesothelioma. Retreatment was safe and resulted in clinically meaningful outcomes, thus suggesting its potential application in the clinical practice of mesothalioma patients.

FUNDING

NIBIT Foundation, Fondazione AIRC, AstraZeneca.

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.

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.

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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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.

Immunotherapy in malignant pleural mesothelioma: a review of literature data

Malignant pleural mesothelioma (MPM) is a rare, aggressive cancer of the pleural surface, associated with asbestos exposure, whose incidence is still growing in some areas of the world. MPM is still considered a rare and an orphan disease with an unchanged median overall survival (OS) ranging from 8 to 14 months and no treatment advances in the last 15 years both in local and advanced disease. In the recent years, chronic inflammation of the mesothelium together with local tumor suppression plays a major role in the malignant transformation. Also, significant heterogeneity in both tumor and the microenvironment is at the basis of MPM biology. Preclinical data have demonstrated the immunogenicity and the lack of an effective antitumor response by the immune system in MPM thus paving the way to the development of immune therapeutics in this disease. Still there is no clear evidence of any predictive biomarker so that, given the close interaction between the immune infiltrate and mesothelial cells, a number of trials are ongoing to investigate the role and prognostic value of the immune microenvironment. In this review we summarize the rationale for immune therapeutics development in MPM, as well as, the relevant literature and ongoing trials of immune checkpoint inhibitors (ICIs) and vaccines used as both first-line treatment and beyond.

Oncological Frontiers in the Treatment of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare malignancy characterized by very poor prognosis and lack of treatment options. Immunotherapy has rapidly emerged as an effective tool for MPM, particularly for tumors of non-epithelioid histology. At the same time, comprehensive genomic sequencing may open the way to new-generation targeted-drugs able to hit specific MPM molecular vulnerabilities. These innovations will possibly enrich, but also dramatically complicate, the elucidation of treatment algorithms. Multidisciplinary integration is urgently needed.

Immune checkpoint inhibitors for unresectable malignant pleural mesothelioma

Unresectable malignant pleural mesothelioma (MPM) is an aggressive disease with a 5-year survival rate of approximately 10%. Recent data suggest that MPM is an immunologically active tumor, in which checkpoint inhibition through the blockade of the anti-cytotoxic T lymphocyte antigen-4 (-CTLA-4) or anti-programmed cell death 1 (PD-1) could play a major therapeutic role. Initially, clinical trials evaluated immune checkpoint inhibitors (ICIs) in the salvage setting after platinum-based chemotherapy with mixed results in terms of efficacy. More recently, the combination of the anti-CTLA-4 agent ipilimumab plus the anti-PD-1 agent nivolumab was tested in the front-line setting, and reported a superior survival as compared to platinum/pemetrexed. While other clinical trials ore ongoing in order to investigate ICIs for MPM, it seems now evident that we have entered a new "era" for the treatment of MPM. In the future, a few issues need to be solved with regard to the use of ICIs for MPM. Among them, there is the identification of biomarkers of sensitivity to immunotherapy that may help enrich the patient population who could benefit the most from treatment, while avoiding for some other patients the potential occurrence of immune-related side effects from therapies that are anticipated to be ineffective.

Malignant mesothelioma: Advances in immune checkpoint inhibitor and mesothelin-targeted therapies

Malignant mesothelioma is an aggressive cancer with a poor prognosis and limited treatment options. For many years, the only US Food and Drug Administration-approved first-line treatment for unresectable mesothelioma was pemetrexed plus cisplatin. However, the recent approval of nivolumab plus ipilimumab as frontline treatment for patients with pleural mesothelioma marks a significant milestone for the treatment of this disease. In this review, the authors describe recent advances in therapeutic strategies for the treatment of patients with advanced, unresectable mesothelioma, highlighting the emerging use of immunotherapy and mesothelin-targeted therapies for the management of malignant mesothelioma.

Old but gold: the role of drug combinations in improving response to immune check-point inhibitors in thoracic malignancies beyond NSCLC

The introduction of immune checkpoint inhibitors (ICIs) in non-oncogene addicted non-small cell lung cancer (NSCLC) has revolutionized the treatment scenario and led to a meaningful improvement in patient prognosis. Disappointingly, the success of ICI therapy in NSCLC has not been fully replicated in other thoracic malignancies as small cell lung cancer (SCLC), malignant pleural mesothelioma (MPM), and thymic epithelial tumors (TETs), due to the peculiar biological features of these disease and to the difficulties in the conduction of well-designed, biomarker-driven clinical trials. Therefore, combination strategies of ICIs plus conventional therapies (either chemotherapy, alternative ICIs or targeted agents) have been implemented. Although first approvals of ICI therapy have been recently granted in SCLC and MPM (in combination with chemotherapy and different ICIs), results remain somewhat modest and limited to a small proportion of patients. This work reviews the trial results of ICI therapy in mesothelioma, SCLC, and TETs and discusses the potential of combining ICIs with old drugs.

Targeting CTLA-4 in cancer: Is it the ideal companion for PD-1 blockade immunotherapy combinations?

Immunotherapy approaches boosting spontaneous and durable antitumor immune responses through immune checkpoint blockade are revolutionizing treatment and patient outcomes in solid tumors and hematological malignancies. Among the various inhibitory molecules employed by the immune system to regulate the adaptive immune responses, cytotoxic T lymphocyte antigen-4 (CTLA-4) is the first successfully targeted immune checkpoint molecule in the clinic, giving rise to significant but selective benefit either when targeted alone or in combination with anti-programmed cell death protein-1 (PD-1) antibodies (Abs). However, the use of anti-CTLA-4 Abs was associated with the incidence of autoimmune-like adverse events (AEs), which were particularly frequent and severe with the use of combinational strategies. Nevertheless, the higher incidence of AEs is associated with an improved clinical benefit indicating treatment response. A prompt recognition of AEs followed by early and adequate treatment with immunosuppressive agents allows the management of these potentially serious AEs. This narrative review aims to summarize CTLA-4 biology, the rationale for the use as a companion for anti-PD-1 Abs in humans with results from the most relevant Phase III clinical trials including anti-CTLA-4 Abs in combination with anti-PD-1 Abs in solid tumors.

Programmed cell death 1 ligand 1 (PD-L1) expression is associated with poor prognosis of malignant pleural mesothelioma patients with good performance status

Malignant pleural mesothelioma (MPM) is often associated with a poor prognosis and options for the treatment of this disease are few. To date, the important role of the immune microenvironment in modifying the disease natural history is well established. The programmed cell death pathway (PD-1/PD-L1) limits the T lymphocyte activation in peripheral tissues when an inflammatory response occurs, and controls the tumour immune escape. PD-L1 is broadly expressed in several malignant tumours and associated with poor clinical outcomes. Thus, the aim of our study is to investigate the potential role of PD-L1 expression in MPM prognosis. Biopsy samples from 198 patients diagnosed with MPM were examined by immunohistochemistry (IHC) and reverse transcription-polymerase chain reaction (RT-PCR) to evaluate PD-L1 protein and gene expression. For PD-L1 protein expression we consider at least 5% membranous staining as positive. Gene expression levels were calculated with ΔΔCt method. Positive expression of PD-L1 by IHC was correlated with worse overall survival (OS; p=0.0225) in MPM patients. PD-L1 positive status was correlated with worse OS in the subgroup of patients with ECOG score <2 (p=0.0004, n=129) and these data were confirmed by multivariate analysis. No significant correlation was found between PD-L1 gene expression and OS. Our results show that PD-L1 evaluated by IHC assay may be a prognostic biomarker for MPM patients with good performance status.