Pembrolizumab as Palliative Immunotherapy in Malignant Pleural Mesothelioma

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.

UV1 telomerase vaccine with ipilimumab and nivolumab as second line treatment for pleural mesothelioma - A phase II randomised trial

PURPOSE

The NIPU-trial investigates the effect of adding the telomerase vaccine UV1 to treatment with ipilimumab and nivolumab for patients with pleural mesothelioma (PM).

METHODS

In this phase 2 open-label trial, patients with PM progressing after first-line chemotherapy were randomised to receive ipilimumab and nivolumab alone (arm B) or combined with UV1 (arm A). The primary endpoint was progression-free survival (PFS) as determined by BICR. It was estimated that 69 PFS events were needed to detect a hazard ratio (HR) of 0.60 with 80% power and a one-sided alpha level of 0.10.

RESULTS

118 patients were randomised. The median PFS determined by blinded independent central review (BICR) was 4.2 months (95%CI 2.9-9.8) in arm A and 4.7 months (95%CI 3.9-7.0) in arm B (HR 1.01, 80%CI 0.75-1.36 P = 0.979), after a median follow-up of 12.5 months (95%CI 9.7-15.6). The investigator-determined median PFS was 4.3 months (95%CI 3.0-6.8) in arm A and 2.9 months (95%CI 2.4-5.5) in arm B (HR 0.60, 80%CI 0.45-0.81 P = 0.025). Confirmed objective response rate (ORR) by BICR was 31% in arm A and 16% in arm B (odds ratio 2.44 80%CI 1.35-4.49 P = 0.056). After a median follow-up time of 17.3 months (95%CI 15.8-22.9), the OS was 15.4 months (95%CI 11.1-22.6) in arm A and 11.1 months (95%CI 8.8-18.1) in arm B, (HR 0.73, 80%CI 0.53-1.0, P = 0.197).

CONCLUSION

The primary endpoint was not met. Predefined analyses of response rates are in favour of adding the vaccine.

Cost Effectiveness and Budget Impact of Nivolumab Plus Ipilimumab Versus Platinum Plus Pemetrexed (with and Without Bevacizumab) in Patients with Unresectable Malignant Pleural Mesothelioma in Switzerland

BACKGROUND

Malignant pleural mesotheliomas (MPMs) are aggressive and often unresectable. In the past, chemotherapy was the standard for palliative treatment. However, immunotherapy with nivolumab+ipilimumab has recently received marketing approval.

OBJECTIVES

This study evaluated the cost effectiveness of nivolumab+ipilimumab versus pemetrexed+platinum (with/without bevacizumab) for Swiss patients with unresectable MPM, overall and by histological subtype.

METHODS

We developed a three-state Markov cohort model with a cycle length of 1 month, a 30-year time horizon, and a discount rate of 3% per year for costs and benefits. The model included the updated survival and treatment-dependent utility results from the Checkmate-743 and MAPS registration trials. A Swiss statutory health insurance perspective was considered with unit costs for 2022 from publicly available and real-world sources. We assumed a willingness-to-pay (WTP) threshold of CHF100,000/QALY. Model robustness was explored in sensitivity and scenario analyses.

RESULTS

Compared with chemotherapy, nivolumab+ipilimumab incurred additional costs of CHF109,115 and 0.57 additional quality-adjusted life-years (QALYs), yielding an incremental cost-effectiveness ratio (ICER) of CHF192,585/QALY (i.e. USD201,829/QALY) gained. Relative to their 2022 list price, nivolumab+ipilimumab may be cost effective if priced at 48% across all histologies. Assuming cisplatin-based instead of carboplatin-based chemotherapy reduced the ICER to CHF158,911/QALY (i.e. USD166,539/QALY). For the non-epithelioid subtype, nivolumab+ipilimumab was cost effective compared with chemotherapy (ICER of CHF97,894/QALY, i.e. USD102,593/QALY). Chemotherapy+bevacizumab was often a dominated strategy or would require a bevacizumab cost reduction to 28%.

CONCLUSIONS

Our model projected nivolumab+ipilimumab to be cost effective for the non-epithelioid subtype but not for all histologies. Substantial discounts for nivolumab+ipilimumab would be necessary to achieve cost effectiveness for all histologies.

Zimberelimab plus chemotherapy as the first-line treatment of malignant peritoneal mesothelioma: A case report and review of literature

BACKGROUND

Malignant peritoneal mesothelioma (MPeM) is a rare cancer with a poor prognosis at advanced stage, and the standard first-line treatment for inoperable patients is chemotherapy. Although combining programmed cell death 1 (PD-1) inhibitors with chemotherapy is generally considered safe and effective in several malignant solid tumors, there are few reports regarding initial immunochemotherapy in advanced MPeM.

CASE SUMMARY

Here, to our knowledge, we present the first case of a patient with epithelioid subtype MPeM, who was treatment-naïve and benefited from initial PD-1 inhibitor plus standard chemotherapy with a prolonged progression-free survival (PFS) and good tolerance. A 49-year-old man was admitted to our hospital for a persistent burning sensation in the abdomen. Computed tomography revealed a solid mass in the lower abdomen, which was subsequently diagnosed histologically as epithelioid subtype MPeM by core needle biopsy. The patient received eight cycles of pemetrexed 800 mg (day 1), cisplatin 60/50 mg (day 1–2), and zimberelimab (PD-1 inhibitor) 240 mg (day 1) every 3 wk. He achieved significant reduction of peritoneal tumors with remarkable improvement in symptoms. The best tumor response was partial remission with a final PFS of 7 mo. No immune-related adverse event occurred during the combination treatment.

CONCLUSION

The outcome of the present case demonstrates the promising anti-tumor activity of immunochemotherapy to treat inoperable MPeM in the future.

Zimberelimab plus chemotherapy as the first-line treatment of malignant peritoneal mesothelioma: A case report and review of literature

BACKGROUND

Malignant peritoneal mesothelioma (MPeM) is a rare cancer with a poor prognosis at advanced stage, and the standard first-line treatment for inoperable patients is chemotherapy. Although combining programmed cell death 1 (PD-1) inhibitors with chemotherapy is generally considered safe and effective in several malignant solid tumors, there are few reports regarding initial immunochemotherapy in advanced MPeM.

CASE SUMMARY

Here, to our knowledge, we present the first case of a patient with epithelioid subtype MPeM, who was treatment-naïve and benefited from initial PD-1 inhibitor plus standard chemotherapy with a prolonged progression-free survival (PFS) and good tolerance. A 49-year-old man was admitted to our hospital for a persistent burning sensation in the abdomen. Computed tomography revealed a solid mass in the lower abdomen, which was subsequently diagnosed histologically as epithelioid subtype MPeM by core needle biopsy. The patient received eight cycles of pemetrexed 800 mg (day 1), cisplatin 60/50 mg (day 1-2), and zimberelimab (PD-1 inhibitor) 240 mg (day 1) every 3 wk. He achieved significant reduction of peritoneal tumors with remarkable improvement in symptoms. The best tumor response was partial remission with a final PFS of 7 mo. No immune-related adverse event occurred during the combination treatment.

CONCLUSION

The outcome of the present case demonstrates the promising anti-tumor activity of immunochemotherapy to treat inoperable MPeM in the future.

Activation of Adaptive and Innate Immune Cells via Localized IL2 Cytokine Factories Eradicates Mesothelioma Tumors

PURPOSE

IL2 immunotherapy has the potential to elicit immune-mediated tumor lysis via activation of effector immune cells, but clinical utility is limited due to pharmacokinetic challenges as well as vascular leak syndrome and other life-threatening toxicities experienced by patients. We developed a safe and clinically translatable localized IL2 delivery system to boost the potency of therapy while minimizing systemic cytokine exposure.

EXPERIMENTAL DESIGN

We evaluated the therapeutic efficacy of IL2 cytokine factories in a mouse model of malignant mesothelioma. Changes in immune populations were analyzed using time-of-flight mass cytometry (CyTOF), and the safety and translatability of the platform were evaluated using complete blood counts and serum chemistry analysis.

RESULTS

IL2 cytokine factories enabled 150× higher IL2 concentrations in the local compartment with limited leakage into the systemic circulation. AB1 tumor burden was reduced by 80% after 1 week of monotherapy treatment, and 7 of 7 of animals exhibited tumor eradication without recurrence when IL2 cytokine factories were combined with anti-programmed cell death protein 1 (aPD1). Furthermore, CyTOF analysis showed an increase in CD69+CD44+ and CD69-CD44+CD62L- T cells, reduction of CD86-PD-L1- M2-like macrophages, and a corresponding increase in CD86+PD-L1+ M1-like macrophages and MHC-II+ dendritic cells after treatment. Finally, blood chemistry ranges in rodents demonstrated the safety of cytokine factory treatment and reinforced its potential for clinical use.

CONCLUSIONS

IL2 cytokine factories led to the eradication of aggressive mouse malignant mesothelioma tumors and protection from tumor recurrence, and increased the therapeutic efficacy of aPD1 checkpoint therapy. This study provides support for the clinical evaluation of this IL2-based delivery system. See related commentary by Palanki et al., p. 5010.

Genomic and transcriptomic analysis of a diffuse pleural mesothelioma patient-derived xenograft library

BACKGROUND

Diffuse pleural mesothelioma (DPM) is an aggressive malignancy that, despite recent treatment advances, has unacceptably poor outcomes. Therapeutic research in DPM is inhibited by a paucity of preclinical models that faithfully recapitulate the human disease.

METHODS

We established 22 patient-derived xenografts (PDX) from 22 patients with DPM and performed multi-omic analyses to deconvolute the mutational landscapes, global expression profiles, and molecular subtypes of these PDX models and compared features to those of the matched primary patient tumors. Targeted next-generation sequencing (NGS; MSK-IMPACT), immunohistochemistry, and histologic subtyping were performed on all available samples. RNA sequencing was performed on all available PDX samples. Clinical outcomes and treatment history were annotated for all patients. Platinum-doublet progression-free survival (PFS) was determined from the start of chemotherapy until radiographic/clinical progression and grouped into < or ≥ 6 months.

RESULTS

PDX models were established from both treatment naïve and previously treated samples and were noted to closely resemble the histology, genomic landscape, and proteomic profiles of the parent tumor. After establishing the validity of the models, transcriptomic analyses demonstrated overexpression in WNT/β-catenin, hedgehog, and TGF-β signaling and a consistent suppression of immune-related signaling in PDXs derived from patients with worse clinical outcomes.

CONCLUSIONS

These data demonstrate that DPM PDX models closely resemble the genotype and phenotype of parental tumors, and identify pathways altered in DPM for future exploration in preclinical studies.

Inhibition of Cyclin Dependent Kinase 4/6 Overcomes Primary Resistance to Programmed Cell Death 1 Blockade in Malignant Mesothelioma

BACKGROUND

Despite the profound number of malignant pleural mesothelioma (MPM) patients now treated with programmed cell death 1 (PD-1) blockade, insight into the underpinnings of rational therapeutic strategies to treat resistance to checkpoint immunotherapy remains unrealized. Our objective was to develop a novel therapeutic approach to overcome primary resistance to PD-1 blockade in MPM.

METHODS

We generated a transcriptome signature of resistance to PD-1 blockade in MPM patients treated with nivolumab (4 responders and 4 nonresponders). We used The Cancer Genome Atlas MPM cohort (n = 73) to determine what genomic alterations were associated with the resistance signature. We tested whether regulation of identified molecules could overcome resistance to PD-1 blockade in an immunocompetent mouse malignant mesothelioma model.

RESULTS

Immunogenomic analysis by applying our anti-PD-1 resistance signature to The Cancer Genome Atlas cohort revealed that deletion of cyclin dependent kinase inhibitor 2A (CDKN2A) was highly associated with primary resistance to PD-1 blockade. Under the hypothesis that resistance to PD-1 blockade can be overcome by cyclin dependent kinase 4/6 (CDK4/6) inhibition, we tested whether CDK4/6 inhibitors could overcome resistance to PD-1 blockade in subcutaneous tumors derived from Cdkn2a-/- AB1 malignant mesothelioma cells, which were resistant to PD-1 blockade. The combination of daily oral administration of CDK4/6 inhibitors (abemaciclib or palbociclib) and intraperitoneal anti-PD-1 treatment markedly suppressed tumor growth compared with anti-PD-1 or CDK4/6 inhibitor alone.

CONCLUSIONS

We identified a therapeutic target, CDK4/6, to overcome primary resistance to PD-1 blockade through comprehensive immunogenomic approaches. These data provide a rationale for undertaking clinical trials of CDK4/6 inhibitors in more than 40% of patients with MPM who demonstrate loss of CDKN2A.

Nivolumab plus ipilimumab in malignant pleural mesothelioma

INTRODUCTION

Unresectable pleural mesothelioma is a poor prognosis disease. Improvement in overall survival (OS) has been shown with PEMETREXED combined to CISPLATIN. BEVACIZUMAB combined with chemotherapy is associated with an improvement in OS, compared to chemotherapy alone, but is not supported by health insurance everywhere.

AREAS COVERED

Immune Checkpoint Inhibition (ICI) monotherapy seemed to be promising, but is controversial. ICI combination showed significant results. NIVOLUMAB, an anti-Programmed-Death-receptor 1, associated to IPILIMUMAB, an anti-Cytotoxic-T-Lymphocyte-Associated-protein 4, was evaluated in two phase II trials and a phase III trial, recently published. This combination led to a significant benefit in survival in first line compared to chemotherapy (OS 18.1 months (95%CI(16.8-21.4)) vs 14.1 (95%CI(12.4-16.2) HR 0.74 (95%CI 0.6-0.91) p=0.002).

EXPERT OPINION

These results represent a big step in unresectable pleural mesothelioma. The benefit in non-epithelioid subtype is impressive (OS 18.1 months (95%CI 12.2-22.8) vs 8.8 months 95%CI (7.4-10.2) HR 0.46 (95%CI(0.31-0.68)). Benefit in epithelioid subtype (OS 18.7 months 95%CI(16.9-22) vs 16.5 95%CI(14.9-20.5) HR 0.86 95%CI(0.69-1.08)) is similar to the benefit of the combination of BEVACIZUMAB and chemotherapy. Identification of predictive biomarkers is needed to identify patients who are most likely to benefit from each therapeutic strategy.

Systemic treatment in patients with malignant pleural mesothelioma - real life experience

Background

Malignant pleural mesothelioma (MPM) is a rare, aggressive malignancy of the pleural cavity linked to asbestos exposure. The combination of pemetrexed and platinum is a standard first-line therapy for malignant pleural mesothelioma. Despite some progress, almost all MPM patients experience progression after first-line therapy. The second-line treatment is still being under discussion and there are very limited data available on the second-line and subsequent treatments.

Methods

The retrospective analysis included 57 patients (16 females and 41 males) from two Polish oncological institutions treated for advanced mesothelioma between 2013 and 2019. We analysed the efficacy of first-line and second-line therapy: progression-free survival (PFS), overall survival (OS), overall response rate (ORR).

Results

In the first-line treatment, 55 patients received pemetrexed-based chemotherapy (PBC) and two cisplatin in monotherapy. Patients’ characteristics at baseline: median age was 64.2 years, ECOG PS ≤ 1 (86.2%), epithelial histology (85.7%). Median PFS and OS were 7.6 months and 14 months, respectively. Patients with ECOG PS ≤ 1 vs > 1 had a longer median OS (14.8 months vs 9.7 months, p = 0.057). One-year OS and PFS were 60.9% and 32.0%, respectively. Disease control rate (DCR) was 82.5%. Response to first-line therapy: PFS ≥ 6 months and PFS ≥ 12 months had a significant impact on median OS. Twelve patients received second-line therapy (seven PBC and five other cytotoxic single agents: navelbine, gemcitabine, or adriamycin/vincristine/methotrexate triplet). Median PFS and OS were 3.7 months and 7.2 months, respectively. DCR was 83%. One-year OS and PFS were 37% and 16.7%, respectively.

In the group receiving PBC, OS was prolonged by 4.5 months compared to the non-PBC group (6.0 months vs 10.5 months, p = 0.47).

Conclusion

Patients who benefited from first-line therapy and had prolonged PFS at first-line and achieve PFS longer than 6 months at first-line should be offered second-line treatment. Consideration of retreatment with the same cytotoxic agent could to be a viable option when no other treatment are available.

Immune-Checkpoint Inhibitors for Malignant Pleural Mesothelioma: A French, Multicenter, Retrospective Real-World Study

Backgrounds: Malignant pleural mesothelioma (MPM) is a cancer with poor prognosis. Second-line and onward therapy has many options, including immune-checkpoint inhibitors with demonstrated efficacy: 10−25% objective response rate (ORR) and 40−70% disease-control rate (DCR) in clinical trials on selected patients. This study evaluated real-life 2L+ nivolumab efficacy in MPM patients and looked for factors predictive of response. Methods: This retrospective study included (September 2017−July 2021) all MPM patients managed in 11 French centers. Results: The 109 enrolled patients’ characteristics were: median age: 69 years; 67.9% men; 82.6% epithelioid subtype. Strictly, second-line nivolumab was given to 51.4%. Median PFS and OS were 3.8 (3.2−5.9) and 12.8 (9.2−16.4) months. ORR was 17/109 (15.6%); 34/109 patients had a stabilized disease (DCR 46.8%). Univariable analysis identified several parameters as significantly (p < 0.05) prognostic of OS [HR (95% CI)]: biphasic subtype: 3.3 (1.52−7.0), intermediate Lung Immune Prognostic Index score: 0.46 (0.22−0.99), progression on the line preceding nivolumab: 2.1 (1.11−3.9) and age > 70 years: 2.5 (1.5−4.0). Multivariable analyses retained only biphasic subtype: 3.57 (1.08−11.8) and albumin < 25 g/L: 10.28 (1.5−70.7) as significant and independent predictors. Conclusions: Second-line and onward nivolumab is effective against MPM in real life but with less effectiveness in >70 years. Ancillary studies are needed to identify the predictive factors.

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.

A Real-World Analysis of the use of Systemic Therapy in Malignant Pleural Mesothelioma and the Differential Impacts on Overall Survival by Practice Pattern

Introduction

Malignant pleural mesothelioma (MPM) is an aggressive malignancy that affects older adults with frequent comorbidities, making real-world treatment decisions challenging. This study compares the overall survival (OS) of patients with MPM by physician’s choice of first-line (1L) platinum chemotherapy (PC), second-line (2L) immunotherapy versus chemotherapy, and by receipt of maintenance therapy (MT).

Methods

The study included patients diagnosed with advanced MPM in the Flatiron Health electronic health record–derived database who initiated PC with pemetrexed in the 1L setting between 2011 and 2019. Patients in the 2L therapy analysis received single-agent chemotherapy versus immunotherapy after the progression of disease from our 1L cohort. Patients in the MT cohort were identified on the basis of continued receipt of pemetrexed with or without bevacizumab after dropping PC at prespecified intervals. The OS of patients by choice of 1L PC, 2L immunotherapy versus chemotherapy, and receipt of MT was summarized by means of Kaplan-Meier survival estimates and compared in the context of propensity score matching weighted analyses.

Results

In propensity score matching weighting analysis from 2065 patients with MPM, there was no evidence of an OS difference by choice of 1L PC (hazard ratio [HR] = 1.08, 95% confidence interval [CI]: 0.89–1.31, p = 0.43), suggestive evidence of an OS difference by choice of 2L immunotherapy versus chemotherapy (HR = 0.68, 95% CI: 0.42–1.08; p = 0.10), and no evidence of an OS difference by receipt of MT (HR = 0.92, 95% CI: 0.72–1.16, p = 0.46).

Conclusions

Using real-world, propensity score–matched weighted analysis of MPM, we found there was no difference in OS by choice of 1L PC, 2L immunotherapy or chemotherapy, or by receipt of MT.

Comparative effectiveness of second-line immune checkpoint inhibitor therapy versus chemotherapy for malignant pleural mesothelioma

OBJECTIVES

Second-line immune checkpoint inhibition (ICI) was recently shown to have a survival advantage over placebo in malignant pleural mesothelioma (MPM), but the survival comparison to chemotherapy in patients with MPM receiving routine clinical care is unknown. Our objective was to examine the effectiveness of second-line ICI versus chemotherapy on overall survival (OS) outcomes in real-world patients with advanced MPM.

MATERIALS AND METHODS

We performed a multicenter retrospective cohort study of real-world adult patients with advanced MPM who received first-line platinum-based chemotherapy and at least two total lines of systemic therapy. Patients received either second-line chemotherapy (gemcitabine and/or vinorelbine) or ICI therapy (pembrolizumab or nivolumab ± ipilimumab). The primary outcome was OS, defined as the time from second-line therapy initiation to death or end of the observation period. We used Kaplan-Meier methods and Cox proportional hazards modeling with adjustment for relevant patient demographic and clinical variables to compare OS between the two second-line treatment groups.

RESULTS

Of the 176 patients with MPM, the median age was 75 years (IQR: 69-79.5 years), and most were white (77%), male (74%), and had epithelioid histology (67%). Thirty-five percent (61) received second-line chemotherapy and 65% (115) ICI therapy (80 pembrolizumab, 31 nivolumab, and 4 nivolumab + ipilimumab). Treatment with ICI was associated with significantly longer median OS compared to chemotherapy (8.7 vs 5.0 months, p=0.001; adjusted hazard ratio: 0.52, 95% CI: 0.34-0.81). The estimated 12-month OS probability was 36.7% (95% CI: 27.6%-45.8%) and 15.6% (95% CI: 7.7%-26.1%) in the ICI and chemotherapy groups, respectively.

CONCLUSION

In this "real-world" population of patients with MPM, treatment with ICI was associated with improved OS outcomes compared to chemotherapy in the second-line setting, in contrast with a recent clinical trial. Our findings suggest that ICI may benefit patients with advanced MPM and progression after initial platinum-based chemotherapy.

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.

The minimum standard of care for managing malignant pleural mesothelioma in developing nations within the Asia-Pacific Region

Malignant pleural mesothelioma (MPM) is an incurable malignancy associated with high symptom burden and poor prognosis. The relationship between asbestos exposure and MPM incidence is well-established. The incidence rate of MPM in Australia and New Zealand is among the highest globally. Matching the experience of other nations with legal restrictions on asbestos, incidence is expected to fall. In contrast, the incidence of MPM is rising in the developing nations of the Asia-Pacific as consumption and mining (albeit to a lesser extent) of asbestos continues. The incidence of MPM in these nations is currently low or unknown, reflecting insufficient latency periods since industrial use of asbestos, deficient resources for accurate diagnosis, and lack of occupational disease or cancer registries. The landscape of treatment for MPM is rapidly changing with combination immunotherapy now demonstrating improved survival in the first-line setting. Considering vast global inequity in access to anticancer treatments, establishing minimum standard of care for MPM in developing nations is of greater significance. Here, we review the evidence that form the basis of our minimum-standard recommendations for diagnosis, systemic treatment, management of recurrent pleural effusions, and symptom management. We also briefly review evidence-based treatment that may be considered for those with access.

Immune Microenvironment and Genetics in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and aggressive malignancy with limited therapeutic options beyond surgery and cytotoxic chemotherapy. The success of immune checkpoint inhibition has been found to correlate with expression of immune-related genes such as CD274 (PD-L1) in lung and other solid cancers. However, only a small subset of MPM patients respond to checkpoint inhibition, and this response has been varied and unpredictable across several clinical trials. Recent advances in next-generation sequencing (NGS) technology have improved our understanding of the molecular features of MPM, also with respect to its genetic signature and how this impacts the immune microenvironment. This article will review current evidence surrounding the interplay between MPM genetics, including epigenetics and transcriptomics, and the immune response.

Immune Checkpoint Inhibitor Uptake in Real-World Patients With Malignant Pleural Mesothelioma

INTRODUCTION

Since the July 2017 National Comprehensive Cancer Network (NCCN) malignant pleural mesothelioma (MPM) guideline revision recommended second-line immune checkpoint inhibitors (ICIs), studies have suggested a greater response to ICI among patients with nonepithelioid MPM. Nevertheless, little is known regarding adoption of ICI in routine practice and if uptake differs by histologic subtype. Our objectives were to evaluate the real-world uptake of second-line ICI among patients with MPM and to reveal its association with histologic subtype.

METHODS

This was a multicenter, retrospective cohort study of real-world patients with MPM receiving at least two lines of systemic therapy between 2011 and 2019. We found the uptake of second-line ICI over time and evaluated the association between histologic subtype and ICI use, adjusting for relevant patient demographic and clinical factors.

RESULTS

Among the 426 patients with MPM in our cohort, 310 had epithelioid and 116 nonepithelioid histologic subtype. The median age was 73 years (interquartile range: 67-78). Overall, 144 patients (33.8%) received second-line ICI and 282 (66.2%) traditional chemotherapy. ICI uptake began in early 2015 before the NCCN guideline revision and increased rapidly to 2019. After the 2017 NCCN guideline revision, patients with nonepithelioid MPM histologic subtypes had more than 3 times the odds of receiving second-line ICI (OR = 3.26; 95% confidence interval: 1.41-7.54).

CONCLUSIONS

Among real-world patients with MPM, second-line ICI uptake began over two years before the 2017 NCCN guideline recommendations and was associated with nonepithelioid histologic subtype after contemporary studies suggested increased clinical benefit in this population, reflecting prompt integration of scientific discovery into clinical practice.

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.

CSF1/CSF1R Axis Blockade Limits Mesothelioma and Enhances Efficiency of Anti-PDL1 Immunotherapy

Simple Summary

CSF1/CSF1R signaling mediates tumor-associated macrophages recruitment and M2 polarization. M2 TAMs are dominant immune populations infiltrating mesothelioma tumors. We evaluated the role of CSF1/CSF1R axis blockade in tumor-infiltrating immune subsets. We also examined the effect of combined anti-CSF1R and anti-PDL1 treatment in mesothelioma progression. We show that CSF1R inhibition impedes mesothelioma progression, abrogates infiltration of TAMs, facilitates an M1 anti-tumor phenotype and activates tumor dendritic and CD8+ T cells. We also show that this inhibitor was able to significantly improve the effectiveness of anti-PDL1 immunotherapy.

Abstract

Colony-Stimulating Factor 1 (CSF1)/Colony-Stimulating Factor Receptor 1 (CSF1R) signaling orchestrates tumor-associated macrophage (TAM) recruitment and polarization towards a pro-tumor M2 phenotype, the dominant phenotype of TAMs infiltrating mesothelioma tumors. We hypothesized that CSF1/CSF1R inhibition would halt mesothelioma growth by targeting immunosuppressive M2 macrophages and unleashing efficient T cell responses. We also hypothesized that CSF1/CSF1R blockade would enhance the efficacy of a PDL1 inhibitor which directly activates CD8+ cells. We tested a clinically relevant CSF1R inhibitor (BLZ945) in mesothelioma treatment using syngeneic murine models. We evaluated the role of CSF1/CSF1R axis blockade in tumor-infiltrating immune subsets. We examined the effect of combined anti-CSF1R and anti-PDL1 treatment in mesothelioma progression. CSF1R inhibition impedes mesothelioma progression, abrogates infiltration of TAMs, facilitates an M1 anti-tumor phenotype and activates tumor dendritic and CD8+ T cells. CSF1R inhibition triggers a compensatory PD-1/PDL1 upregulation in tumor and immune cells. Combined CSF1R inhibitor with an anti-PDL1 agent was more effective in retarding mesothelioma growth compared to each monotherapy. In experimental mesotheliomas, CSF1R inhibition abrogates tumor progression by limiting suppressive myeloid populations and enhancing CD8+ cell activation and acts synergistically with anti-PDL1.

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.

Drug Regimen for Patients after a Pneumonectomy

Pneumonectomy is an entire lung removal and is indicated for both malignant and benign diseases. Due to its invasiveness and postoperative complications, pneumonectomy is still associated with high mortality and morbidity. Appropriate postoperative management is crucial in pneumonectomy patients to improve quality of life and overall survival rates. Diverse drug regimens are under development to be used in adjuvant chemotherapy or to improve respiratory health after a pneumonectomy. The most common causes for a pneumonectomy are non-small cell lung cancer, malignant pleural mesothelioma, and tuberculosis; thus, an appropriate drug regimen is necessary. The uncommon incidence of pneumonectomy cases remains the major obstacle in studies of postoperative drug regimens. As the majority of current studies include post-lobectomy and post-segmentectomy patients, it is highly recommended that further research of postoperative drug regimens be focused on post-pneumonectomy patients.

Treatment patterns and outcomes of patients with advanced malignant pleural mesothelioma in a community practice setting

Aim: To assess real-world treatment patterns and outcomes among patients with advanced malignant pleural mesothelioma. Patients & methods: Retrospective database analysis. Results: In all, 469 patients received first-line systemic anticancer therapy (SACT) at community centers. Median follow-up from diagnosis was 11.6 months. Pemetrexed + platinum was the most common first-line SACT; similar proportions of patients received cisplatin or carboplatin with pemetrexed. Only a small proportion of patients received second- and third-line therapies. Median overall survival for first-line SACT was 12.0 months (95% CI: 10.7-14.2). Results were similar with pemetrexed + cisplatin and pemetrexed + carboplatin. Median overall survival with second-line SACT was 6.4 months (95% CI: 5.1-7.6). Conclusion: There is a need for more effective SACTs for advanced malignant pleural mesothelioma.

Malignant mesothelioma without asbestos exposure diagnosed during EGFR-TKI treatment of lung adenocarcinoma: A case report

Synchronous malignant mesothelioma (MM) and lung carcinoma are extremely rare in patients without a history of asbestos exposure and poses tremendous difficulties in clinical management. We report a patient without asbestos exposure diagnosed with MM during EGFR-TKI treatment of lung adenocarcinoma (LUAD), who responded to first-line chemotherapy with pemetrexed plus carboplatin and failed to subsequent systemic therapy. Clinicians should be careful about the possibility of MM comorbidity in LUAD patients whose lesions respond differently to EGFR-TKI, even in those without a history of asbestos exposure.

Pembrolizumab-induced myocarditis in a patient with malignant mesothelioma: plasma exchange as a successful emerging therapy-case report

Malignant mesothelioma is an aggressive cancer associated with prior exposure to asbestos and dismal prognosis. Immune checkpoint inhibitor therapy is currently approved by the Food and Drug Administration for pre-treated malignant pleural mesothelioma. We describe a 75-year-old patient with disseminated, progressive malignant mesothelioma receiving 2 cycles of pembrolizumab who presented with generalized muscle weakness, shortness of breath, double vision and ptosis. There was no previous history of cardiovascular disease. The clinical picture, supported by the detection of anti-titin autoantibodies suggested myasthenia gravis (MG). Also, cardiac biomarkers were elevated. Echocardiography showed new severely reduced ejection fraction. A 12-lead resting electrocardiogram (ECG) revealed ST segment elevation in the posterior leads with polymorphic ventricular extrasystoles. Because cardiac catheterization revealed no relevant coronary lesions, immune checkpoint inhibitor-associated myocarditis and MG were suspected. Management and Outcome: The patient was started on steroids. Within a few days of presentation respiratory failure set in and the patient was intubated. Recurrent arrhythmias followed, which were treated by repeated emergency electrical cardioversion. In order to relieve myasthenic symptoms, plasma exchange was initiated and 10 cycles were carried out. This consequently also led to an improvement of myocarditis. Upon discharge, the ejection fraction recovered. The patient recovered and was alive at 1-year follow-up, without relevant limitations to his quality of life. Discussion and Conclusion: The article further discusses the use of plasma exchange for immune checkpoint inhibitor-associated myocarditis based on a review of literature. We conclude that patients showing no improvement after steroid therapy for immune checkpoint inhibitor-related myocarditis should be evaluated for plasma exchange, which appears to be an effective treatment option.

Exceptional Regression of Malignant Pleural Mesothelioma with Pembrolizumab Monotherapy

The lead author with clinical stage I malignant pleural mesothelioma, epithelioid type, highly programmed cell death ligand 1 (PD-L1) positive, and BAP1 negative, experienced a prompt and exceptionally favorable response to pembrolizumab monotherapy. After cessation of treatment due to immune-related endocrinopathies, complete metabolic response on interim PET/CT scan was achieved. Two years after initial diagnosis, unifocal tumor reactivation was addressed with successful pembrolizumab monotherapy rechallenge. Immunotherapy, typically not used as frontline treatment for malignant pleural mesothelioma, may provide an effective and durable response for some patients. Based on this single case study, epithelioid type tumors with strongly positive PD-L1 and BAP1-negative immunohistochemical markers may be well suited for treatment with immune checkpoint inhibitors such as pembrolizumab.

A Review of Pharmacologic Management in the Treatment of Mesothelioma

OPINION STATEMENT

Mesothelioma is a rare and severe form of cancer that is associated with asbestos exposure. Approximately 2500 Americans die annually from this condition with a median survival of 1 year. The latency period of this disease ranges anywhere from 20 to 70 years, with shorter latency periods associated with a higher exposure intensity to asbestos. Therefore, cases of mesothelioma are expected in the coming decades. This highlights the need for clinicians to understand the pharmacologic regimens available for treating this rare, yet serious malignancy. With multiple treatment regimens available in the treatment of this condition, clinicians should take an evidence-based approach and consider the totality of evidence and safety information while considering the best patient-centered approach for treatment. This article provides a review of current pharmacologic treatment options available for mesothelioma and goes into detail about the recommended medication regimens and dosages and the available evidence of efficacy, effectiveness, and/or safety and estimates the annual cost of treatment for these medications on the U.S. healthcare system per patient. A brief introduction is provided for several promising agents currently under investigation for mesothelioma as well.

Establishment and Characterization of Patient-Derived Xenografts (PDXs) of Different Histology from Malignant Pleural Mesothelioma Patients

Simple Summary

Malignant pleural mesothelioma (MPM) is a rare tumor with unfavorable prognosis for which new therapeutic interventions are urgently needed. The aim of our study was to develop a preclinical model representative of the different histotypes found in human tumors that can be used as models for the discovery of new treatments and combinations. We successfully generated patient-derived xenografts (PDXs) from MPM, which strongly resembled the tumors of origin in terms of morphology and immunohistochemistry. These tumors, when growing in mice, poorly respond to cisplatin, a finding that aligned with the clinical results. From one of the PDXs, we generated 2D and 3D cultures maintaining the phenotypical characteristics of human tumors and PDXs. Altogether, these preclinical models represent a useful tool for the discovery of new targets and drug combinations.

Abstract

Background: Malignant pleural mesothelioma (MPM) is a very aggressive tumor originating from mesothelial cells. Although several etiological factors were reported to contribute to MPM onset, environmental exposure to asbestos is certainly a major risk factor. The latency between asbestos (or asbestos-like fibers) exposure and MPM onset is very long. MPM continues to be a tumor with poor prognosis despite the introduction of new therapies including immunotherapy. One of the major problems is the low number of preclinical models able to recapitulate the features of human tumors. This impacts the possible discovery of new treatments and combinations. Methods: In this work, we aimed to generate patient-derived xenografts (PDXs) from MPM patients covering the three major histotypes (epithelioid, sarcomatoid, and mixed) occurring in the clinic. To do this, we obtained fresh tumors from biopsies or pleurectomies, and samples were subcutaneously implanted in immunodeficient mice within 24 h. Results: We successfully isolated different PDXs and particularly concentrated our efforts on three covering the three histotypes. The tumors that grew in mice compared well histologically with the tumors of origin, and showed stable growth in mice and a low response to cisplatin, as was observed in the clinic. Conclusions: These models are helpful in testing new drugs and combinations that, if successful, could rapidly translate to the clinical setting.

Simultaneous tongue metastasis from malignant pleural mesothelioma: Case report and literature review

Malignant pleural mesothelioma (MPM) is a rare neoplasm of the serosal membranes. MPM usually manifests as local invasion, rarely with distant haematogenous metastases in different organs. Few cases of tongue metastasis have been documented. Here, we report the case of a 68-year-old man diagnosed with malignant pleural epithelioid mesothelioma together with a simultaneous tongue lesion, which was found to be metastatic malignant mesothelioma. Tongue metastasis from MPM is rare and the oral symptoms it causes could be an early sign of clinical manifestation. For patients with oral symptoms and a newly discovered tongue lesion, clinicians should be aware of the possibility of tongue metastasis and search for a primary malignancy.

Prognostic Role of Programmed Cell Death 1 Ligand 1 in Resectable Pleural Mesothelioma

BACKGROUND

The prognostic role of programmed cell death 1 ligand 1 (PD-L1) in malignant pleural mesothelioma (MPM) is incompletely understood. Our objectives were to evaluate the evidence for tumor PD-L1 as a prognostic biomarker in MPM through meta-analysis and to determine whether tumor PD-L1 expression is associated with survival in MPM patients undergoing macroscopic complete resection.

METHODS

Meta-analysis was performed to determine the association of PD-L1 with overall survival in MPM (n = 1655) from 14 studies containing overall survival and tumor PD-L1 expression. Univariable and multivariable analyses tested the relationship of tumor PD-L1 with overall survival and recurrence-free survival in an institutional cohort of MPM patients treated by macroscopic complete resection (n = 75). To validate the association of PD-L1 with overall survival, we utilized two independent MPM cohorts (n = 284).

RESULTS

Meta-analysis demonstrated that high tumor PD-L1 expression was associated with poor overall survival. Among 75 patients undergoing macroscopic complete resection, 49 tumors (65%) expressed PD-L1 (1% or more), and high PD-L1 (50% or greater) was more commonly expressed on nonepithelial (29%) compared with epithelial tumors (14%). High tumor PD-L1 expression was independently associated with poor overall survival (P < .001, hazard ratio 5.67) and recurrence-free survival (P = .003, hazard ratio 3.28). The association of PD-L1 overexpression with unfavorable survival was more significant in epithelial MPMs than nonepithelial MPMs. These findings were validated in RNA sequencing analyses in two independent cohorts. Exploratory transcriptome analysis revealed that MPM tumors with PD-L1 overexpression displayed coexpression of other immune regulatory molecules, programmed cell death 1 ligand 2 and T-cell immunoglobulin mucin receptor 3.

CONCLUSIONS

Tumor PD-L1 expression is a prognostic biomarker in patients undergoing surgical resection for MPM and may be useful in perioperative decision making.

Retrospective Evaluation of the Use of Pembrolizumab in Malignant Mesothelioma in a Real-World Australian Population

INTRODUCTION

We investigated the efficacy and toxicity of pembrolizumab in patients with mesothelioma from a real-world Australian population. We aimed to determine clinical factors and predictive biomarkers that could help select patients who are likely to benefit from pembrolizumab.

METHOD

Patients with mesothelioma who were treated with pembrolizumab as part of the Insurance and Care New South Wales compensation scheme were included. Clinical information was collected retrospectively. Tumor biomarkers such as programmed death-ligand 1 (PD-L1), BAP1, and CD3-positive (CD3+) tumor-infiltrating lymphocytes (TILs) were examined using archival formalin-fixed paraffin-embedded tumor samples.

RESULTS

A total of 98 patients were included with a median age of 70 years (range, 46-91 y); 92% were men; 76% had epithelioid subtype; 21% had an Eastern Cooperative Oncology Group (ECOG) performance status of 0. Pembrolizumab was used as second-line or subsequent-line treatment in 94 patients and as first-line treatment in four patients. The overall response rate was 18%, and the disease control rate was 56%. The median progression-free survival (PFS) was 4.8 months (95% confidence interval: 3.6-6.2), and the median overall survival (OS) was 9.5 months (95% confidence interval: 6.6-13.7). Immune-related adverse events occurred in 27% of patients, of which nine (9%) were of grade 3 or higher. In the multivariable analysis, factors independently associated with longer PFS included baseline ECOG status of 0 (median PFS: 12 mo versus 4 mo, p < 0.01) and PD-L1 tumor proportion score of greater than or equal to 1% (median PFS: 6 mo versus 4 mo, p < 0.01). Baseline platelet count of less than or equal to 400 × 109/liter was independently associated with longer PFS and OS (median PFS: 6 mo versus 2 mo, p = 0.05; median OS: 10 mo versus 4 mo, p = 0.01), whereas lack of pretreatment dexamethasone was independently associated with OS but not PFS (median OS: 10 mo versus 3 mo, p = 0.01). The odds of response were higher for patients with baseline ECOG status of 0 (p = 0.02) and with greater than or equal to 5% CD3+ TILs in the tumor (p < 0.01). PD-L1 expression, BAP1 loss, and CD3+ TILs in the stroma were not significantly associated with the overall response rate.

CONCLUSIONS

Immunotherapy is a reasonable treatment option for patients with mesothelioma. Our results are comparable to other clinical trials investigating pembrolizumab in mesothelioma in terms of response. Good performance status assessment remains the most robust predictor for patient outcomes. CD3+ TILs in the tumor may help select patients that are likely to respond to pembrolizumab, whereas factors such as PD-L1 expression, baseline platelet count, and lack of pretreatment dexamethasone may help predict survival outcomes from pembrolizumab treatment.

Expression status of PD-L1 and B7-H3 in mesothelioma

Mesothelioma is a rare, aggressive malignancy with poor outcome, and has limited treatment options. The aim of this study was to perform a comprehensive analysis of programmed death ligand 1 (PD-L1) and B7 homolog 3 (B7-H3) expression in mesothelioma. We investigated the protein expression of PD-L1 and B7-H3 and their potential correlation with histological subtype, which might help to develop new therapies targeting these immune checkpoint molecules. Expression analysis of PD-L1 and B7-H3 was performed by immunohistochemistry using serial tissue sections of specimens obtained from 31 patients with mesothelioma. Tumors were classified into 22 epithelioid, 6 sarcomatoid, and 3 biphasic types. Of the 31 patients, 13 (41.9%) were positive for PD-L1 and 28 (90.3%) were B7-H3 positive. Twelve of the 13 PD-L1 positive patients were positive for B7-H3. PD-L1 and B7-H3 were widely co-expressed in biphasic and sarcomatoid type tumor cells. These findings might provide a rationale for the use of combination therapy for mesothelioma by targeting PD-L1 and B7-H3, as well as the development of anti-B7-H3 or anti-PD-L1 single agents.

Characterization of the immune microenvironment in malignant pleural mesothelioma reveals prognostic subgroups of patients

Malignant pleural mesothelioma (MPM) is a rare tumor with an extremely poor prognosis. Its pathogenesis is related to an immune response against asbestos fibers. The T-lymphocytes, including CD8^POS and CD4^POS cells, are an important part of the MPM immune microenvironment, and likely contribute to the therapy resistance observed in these tumors. Here, we sought to characterize the MPM-specific lymphocytes subpopulations within the tumor immune microenvironment to identify novel clinically relevant immunologic subtypes of tumors. Representative formalin-fixed, paraffin-embedded (FFPE) tissue blocks of 88 MPMs were included in tissue microarrays and subjected to tumor-infiltrating lymphocytes (TILs) quantification and subtyping by immunohistochemistry (IHC) with antibodies specific for CD4, CD8, and CD19. Further, PD-L1 (clone 22C3) expression was assessed by IHC as a combined positive score (CPS). Our data show that PD-L1 expression by tumor cells or the presence of a sarcomatoid component is related to increased stromal TILs presence in MPM. Survival analyses showed that low CD4^POS and high CD8^POS stromal TILs are associated with poor patients' survival. In MPMs with PD-L1 CPS > 1, stromal CD8^HIGH was a poor prognostic factor, akin stromal CD4^POS peritumoral TILs correlated with a worse prognosis. Furthermore, we demonstrated that a high CD4^POS/CD8^POS ratio in the tumor immune microenvironment is an independent prognostic factor for survival. Finally, we provided evidence that the characterization of the stromal immune landscape of MPM predicts responses to chemotherapy in subgroups of MPM. The results of this study provide novel insights into the clinical scenario of immune-related biomarkers in MPM.

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

BACKGROUND

The prognostic value of programmed death-ligand 1 (PD-L1) expression in patients with malignant pleural mesothelioma (MPM) has been controversial according to previous investigations. Therefore, we conducted a meta-analysis to assess the potential prognostic significance of PD-L1 expression in MPM.

METHODS

PubMed, Embase, Web of Science, Scopus, and the Cochrane Library were thoroughly searched for relevant original articles published before 9 April 2020. The pooled hazard ratios (HRs) and 95% confidence intervals (CIs) of overall survival (OS) and progression-free survival (PFS) were calculated. The results of the meta-analysis were verified using The Cancer Genome Atlas (TCGA) dataset.

RESULTS

In total 16 studies were included in our meta-analysis. A high PD-L1 expression was associated with a poor OS (HR = 1.53, 95% CI = 1.28-1.83, p < 0.001), but not a grave PFS (HR = 1.07, 95% CI = 0.82-1.39, p = 0.643) in MPM. Furthermore, the PD-L1 expression correlated with the sarcomatoid + biphasic type of MPM (odds ratio = 4.32, 95% CI = 2.16-8.64, p < 0.001). TCGA data indicated that PD-L1 was a significant prognostic factor for OS (HR = 2.069, 95% CI = 1.136-3.769, p = 0.0175), but not for PFS (HR = 1.205, 95% CI = 0.572-2.539, p = 0.624), which was in accordance with the results of the meta-analysis.

CONCLUSION

A high PD-L1 expression is a significant prognostic factor for poor OS of patients with MPM. We therefore suggest that PD-L1 expression levels can be used to predict the clinical outcomes of patients with MPM in the future.

AXL Inactivation Inhibits Mesothelioma Growth and Migration via Regulation of p53 Expression

Malignant mesothelioma is a locally aggressive and highly lethal neoplasm. Dysregulation and activation of Gas6/AXL tyrosine kinase signaling are associated with mesothelioma progression, but the mechanisms of these AXL tumorigenic roles are poorly understood. p53 mutants in lung carcinoma upregulate AXL expression by binding and acetylating the AXL promoter. Although TP53 mutations are uncommon in mesothelioma, we hypothesized that these tumors might have alternative feedback mechanisms between AXL and p53. In the current report, we investigated AXL regulation of TP53 transcription, expression, and biological function in mesothelioma. AXL expression was stronger in mesothelioma than most of the other tumor types from the TCGA gene expression profile dataset. AXL knockdown by shRNA induced wild-type and mutant p53 expression in mesothelioma cell lines, suggesting that AXL pro-tumorigenic roles result in part from the suppression of p53 function. Likewise, induced AXL inhibited expression of wild type p53 in COS-7 cells and 293T cells. Immunofluorescence staining showed nuclear colocalization of AXL and p53; however, association of AXL and p53 was not demonstrated in immunoprecipitation complexes. The AXL effects on p53 expression resulted from the inhibition of TP53 transcription, as demonstrated by qRT-PCR after AXL silencing and TP53 promotor dual luciferase activity assays. Chromatin immunoprecipitation-qPCR and sequencing showed that AXL bound to the initial 600 bp sequence at the 5' end of the TP53 promoter. AXL inhibition (shRNA or R428) reduced mesothelioma cell viability, migration, and invasion, whereas TP53 shRNA knockdown attenuated antiproliferative, migration, and invasive effects of AXL silencing or AXL inactivation in these cells. These studies demonstrate a novel feedback regulation loop between AXL and p53, and provide a rationale for mesothelioma therapies targeting AXL/p53 signaling.

Durvalumab with first-line chemotherapy in previously untreated malignant pleural mesothelioma (DREAM): a multicentre, single-arm, phase 2 trial with a safety run-in

BACKGROUND

There is a strong unmet need to improve systemic therapy in mesothelioma. Chemotherapy with cisplatin and pemetrexed improves survival in malignant pleural mesothelioma, and immune checkpoint inhibitors are an emerging treatment in this disease. We aimed to evaluate the activity of durvalumab, an anti-PD-L1 antibody, given during and after first-line chemotherapy with cisplatin and pemetrexed in patients with advanced malignant pleural mesothelioma.

METHODS

DREAM was a multicentre, single-arm, open-label, phase 2 trial done in nine hospitals in Australia. Eligible patients were aged 18 years or older and had histologically confirmed malignant pleural mesothelioma considered unsuitable for cancer-directed surgery, an Eastern Cooperative Oncology Group performance status of 0 or 1, and measurable disease as per the modified Response Evaluation Criteria in Solid Tumors version 1.0 (mRECIST) for mesothelioma that was previously untreated with systemic therapy. All histological subtypes were eligible. The first six participants were treated for two cycles in a safety run-in. All participants received cisplatin 75 mg/m², pemetrexed 500 mg/m², and durvalumab 1125 mg intravenously on day 1 of a 3-weekly schedule for a maximum of six cycles. Change from cisplatin to carboplatin with an area under the curve of 5 was permitted. Durvalumab was continued for a maximum of 12 months. The primary endpoint was progression-free survival at 6 months, measured according to mRECIST for malignant pleural mesothelioma and analysed in the intention-to-treat population. Safety analyses included all participants who receive at least one dose of any study drug. This study is registered with the Australia New Zealand Clinical Trials Registry, ACTRN12616001170415.

FINDINGS

Between Dec 28, 2016, and Sept 27, 2017, 55 participants were enrolled. 54 patients were eligible and were followed up for a median of 28·2 months (IQR 26·5-30·2). 31 (57%; 95% CI 44-70) of 54 patients were alive and progression-free at 6 months. The most common grade 3-4 adverse events were neutropenia (seven [13%] patients), nausea (six [11%]), and anaemia (four [7%]). A total of 60 serious adverse events occurred in 29 participants, five of which were considered possibly related to durvalumab. Five patients died during the study treatment; none of these five deaths were attributed to study treatment.

INTERPRETATION

The combination of durvalumab, cisplatin, and pemetrexed has promising activity and an acceptable safety profile that warrants further investigation in a randomised phase 3 trial.

FUNDING

AstraZeneca.

A multicentre randomised phase III trial comparing pembrolizumab versus single-agent chemotherapy for advanced pre-treated malignant pleural mesothelioma: the European Thoracic Oncology Platform (ETOP 9-15) PROMISE-meso trial

BACKGROUND

Malignant pleural mesothelioma (MPM) is an aggressive malignancy characterised by limited treatment options and a poor prognosis. At relapse after platinum-based chemotherapy, single-agent chemotherapy is commonly used and single-arm trials of immune-checkpoint inhibitors have demonstrated encouraging activity.

PATIENTS AND METHODS

PROMISE-meso is an open-label 1:1 randomised phase III trial investigating the efficacy of pembrolizumab (200 mg/Q3W) versus institutional choice single-agent chemotherapy (gemcitabine or vinorelbine) in relapsed MPM patients with progression after/on previous platinum-based chemotherapy. Patients were performance status 0-1 and unselected for programmed cell death ligand 1 (PD-L1) status. At progression, patients randomly assigned to receive chemotherapy were allowed to crossover to pembrolizumab. The primary end point was progression-free survival (PFS), assessed by blinded independent central review (BICR). Secondary end points were overall survival (OS), investigator-assessed PFS, objective response rate (ORR), and safety. Efficacy by PD-L1 status was investigated in exploratory analyses.

RESULTS

Between September 2017 and August 2018, 144 patients were randomly allocated (pembrolizumab: 73; chemotherapy: 71). At data cut-off [20 February 2019, median follow-up of 11.8 months (interquartile range: 9.9-14.5)], 118 BICR-PFS events were observed. No difference in BICR-PFS was detected [hazard ratio = 1.06, 95% confidence interval (CI): 0.73-1.53; P = 0.76], and median BICR-PFS (95% CI) for pembrolizumab was 2.5 (2.1-4.2), compared with 3.4 (2.2-4.3) months for chemotherapy. A difference in ORR for pembrolizumab was identified (22%, 95% CI: 13% to 33%), over chemotherapy (6%, 95% CI: 2% to 14%; P = 0.004). Forty-five patients (63%) assigned to chemotherapy received pembrolizumab at progression. With follow-up to 21 August 2019 [17.5 months: (14.8-19.7)], no difference in OS was detected between groups (HR = 1.12, 95% CI: 0.74-1.69; P = 0.59), even after adjusting for crossover. Pembrolizumab safety was consistent with previous observations. Exploratory efficacy analyses by PD-L1 status demonstrated no improvements in ORR/PFS/OS.

CONCLUSION

This is the first randomised trial evaluating the efficacy of pembrolizumab in MPM patients progressing after/on previous platinum-based chemotherapy. In biologically unselected patients, although associated with an improved ORR, pembrolizumab improves neither PFS nor OS over single-agent chemotherapy.

Recommendations for detection, prioritization, and treatment of thoracic oncology patients during the COVID-19 pandemic: the THOCOoP cooperative group

The world currently faces a pandemic due to SARS-CoV-2. Relevant information has emerged regarding the higher risk of poor outcomes in lung cancer patients. As such, lung cancer patients must be prioritized in terms of prevention, detection and treatment. On May 7th, 45 experts in thoracic cancers from 11 different countries were invited to participate. A core panel of experts regarding thoracic oncology care amidst the pandemic gathered virtually, and a total of 60 initial recommendations were drafted based on available evidence, 2 questions were deleted due to conflicting evidence. By May 16th, 44 experts had agreed to participate, and voted on each of the 58 recommendation using a Delphi panel on a live voting event. Consensus was reached regarding the recommendations (>66 % strongly agree/agree) for 56 questions. Strong consensus (>80 % strongly agree/agree) was reached for 44 questions. Patients with lung cancer represent a particularly vulnerable population during this time. Special care must be taken to maintain treatment while avoiding exposure.

Symptom Burden and Unmet Needs in Malignant Pleural Mesothelioma: Exploratory Analyses From the RESPECT-Meso Study

OBJECTIVE

Malignant Pleural Mesothelioma (MPM) has a poor prognosis and high symptom burden. RESPECT-Meso was a multicenter randomized study examining the role of early specialist palliative care (SPC) on quality of life (QoL) with MPM. This is a post-hoc exploratory analysis of the symptom burden and unmet needs identified from RESPECT-Meso participants.

METHODS

Exploratory analysis from 174 participants using the General Health Status (GHS) measure (from the EORTC QLQ-C30 QoL questionnaire) and 87 participants using validated assessment questionnaires in those randomized to SPC. Eligibility for the study included confirmed MPM with diagnosis <6 weeks prior, performance score (PS) 0 or 1, no significant physical or psychological comorbidity. Cox proportional hazards models were derived to examine for relationships with survival. Free text was assessed using content analysis, looking for common themes and words.

RESULTS

Participants were predominantly male (79.9%), mean age 72.8 years, PS was 0 in 38%, 78% of MPM was epithelioid. At least 3 symptoms were reported in 69.8% of participants, including fatigue (81%), dyspnea (73.3%), pain (61.2%), weight loss (59.3%). Anxiety was reported by 54.7% of participants, 52.3% low mood and 48.8% anhedonia symptoms. After multivariable adjustment, only pain remained statistically significant with a hazard ratio (HR) 2.9 (95% CI 1.3-6.7; p = 0.01). For each 1 unit increase in GHS score, the HR for death was 0.987 (0.978-0.996; p = 0.006), indicating a worse reported QoL is related to shorter survival. Unmet needs were common: 25.9% wanted more information about their condition, 24.7% about their care and 21.2% about their treatment. 79.1% were concerned about the effect of their illness on family.

CONCLUSION

There is a high symptom burden in mesothelioma despite good baseline performance status. A worse QoL is associated with a worse survival. Unmet needs are common, perhaps highlighting a need for improved communication and information sharing.

Utility of Nuclear Grading System in Epithelioid Malignant Pleural Mesothelioma in Biopsy-heavy Setting: An External Validation Study of 563 Cases

Nuclear grading systems for epithelioid malignant pleural mesothelioma (MPM) have been proposed but it remains uncertain if they could be applied in a biopsy-heavy setting. Using the proposed system, we conducted an independent, external validation study using 563 consecutive cases of epithelioid MPM diagnosed at our institution between 2003 and 2017, of which 87% of patients underwent biopsies only. The median number of sites sampled was 1, with a median maximum tissue dimension of 17 mm (biopsy) and 150 mm (resection). The median overall survival (OS) was 14.7 months. The frequencies of grade I, II, and III tumors were 31% (132/563), 52% (292/563), and 17% (94/563). Grade I tumors were associated with the most favorable median OS (24.7 mo) followed by grades II (12.7 mo) and III (7.2 mo). The 2-tier nuclear grade separated tumors into low grade (19.3 mo) and high grade (8.9 mo). In multivariate analysis, 3-tier nuclear grade, 2-tier nuclear grade, and mitosis-necrosis score predicted OS independent of age, procedural type, solid-predominant growth pattern, necrosis, and atypical mitosis (all P<0.001 except 2-tier nuclear grade, P=0.001). In the scenario of a single- site biopsy with tissue dimension ≤10 mm, none but age (P=0.002) were independently predictive. Our data also suggested sampling 3 sites or a maximum tissue dimension of at least 20 mm from a single site is optimal for nuclear grade assessment. In conclusion our study confirmed the utility of nuclear grade in epithelioid MPM using a biopsy-heavy cohort provided the tissue sample met minimum dimensional criteria.

Nivolumab in pre-treated malignant pleural mesothelioma: real-world data from the Dutch expanded access program

Background

Randomized phase III trials are ongoing to investigate the efficacy of nivolumab in malignant pleural mesothelioma (MPM), but real-world data are still scarce. In this real-world study, we investigated the clinical outcomes of nivolumab treatment in pre-treated MPM patients.

Methods

Data from 107 nivolumab treated MPM patients within the Dutch expanded access program were retrospectively analyzed. Treatment was independent of programmed death ligand 1 (PD-L1) expression on tumor samples. Univariable and multivariable analyses were performed to evaluate the relationship between clinically important factors, baseline peripheral blood parameters and survival. The landmark method was used to compare the outcome of patients according to their radiological response.

Results

In the full cohort, the median progression-free survival (mPFS) was 2.3 months (95% CI: 1.6–2.9) and the median overall survival (mOS) was 6.7 months (95% CI: 6.2–10.0). After 12 weeks, the disease control rate (DCR) was 37% and the objective response rate (ORR) was 10%. PD-L1 status was determined in 33 patients (30%) and PD-L1 positivity (≥1%) was associated with an improved ORR (36% vs. 9%, P value 0.05), but not with PFS or OS. Low albumin was associated with worse OS (P value 0.002). Median OS was significantly longer for patients who had partial response to treatment (P value 0.0002).

Conclusions

In this real-world analysis, ORR and mOS were lower compared to those obtained in phase II trials. However, exceptional survival rates were observed in patients who had a radiological response. Although we cannot determine whether prognostic or predictive, PD-L1 expression and albumin were associated with greater response rate and may represent useful biomarkers for nivolumab treatment in MPM.

Volumetric PET Response Assessment Outperforms Conventional Criteria in Patients Receiving High-Dose Pembrolizumab for Malignant Mesothelioma

Fixed-dose pembrolizumab (200 mg absolute, day 1, every 3 wk) for the treatment of malignant pleural mesothelioma did not result in survival benefit in the phase 3 PROMISE-meso trial compared with second-line chemotherapy. Because of lack of validated imaging response criteria, responder subgroups with potential survival benefit have not yet been identified. Here, we administered high-dose pembrolizumab (10 mg/kg, day 1, every 2 wk) considering the KEYNOTE-028 trial and assessed the prognostic value of PET metabolic response in patients with chemotherapy-resistant malignant mesothelioma of the pleura or peritoneum. Methods: Data from 27 patients with baseline and follow-up ¹⁸F-FDG PET/CT imaging were retrospectively analyzed. RECIST, version 1.1; modified RECIST; and PERCIST using both tumor lesion metabolic activity in a 1 cm³ spheric region of interest of up to 5 target lesions (PERCIST_SULpeak) and metabolic tumor volume PERCIST (PERCIST_MTV) were applied separately to categorize responders in CT and PET imaging studies. Progression-free survival (PFS) and overall survival (OS) were compared between responders and nonresponders using Kaplan-Meier and log-rank analyses. Programmed cell death protein 1 ligand expression status was assessed, and its association with outcome was investigated. Results: Twenty-seven patients had ¹⁸F-FDG PET/CT imaging at baseline and after at least 4 cycles pembrolizumab. Median PFS and OS were 3.4 and 15.1 mo, respectively. Response rates were 7%, 7%, 30%, and 30% based on RECIST, modified RECIST, PERCIST_SULpeak, and PERCIST_MTV response criteria, respectively. Response according to PERCIST_MTV predicted prolonged OS or PFS (P < 0.01), whereas all other imaging criteria and programmed cell death protein 1 ligand expression did not. Conclusion: ¹⁸F-FDG PET metabolic volume response predicts survival in patients with malignant mesothelioma receiving high-dose pembrolizumab. These results should prompt inclusion of PET response assessment in future phase 3 clinical trials.

Cellular Immunotherapy and Locoregional Administration of CAR T-Cells in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a treatment recalcitrant tumor with a poor overall survival (OS). Current approved treatment consists of first line chemotherapy that only modestly increases OS, illustrating the desperate need for other treatment options in MPM. Unfortunately, clinical studies that investigate the effectivity of checkpoint inhibitor (CI) treatment failed to improve clinical outcome over current applied therapies. In general, MPM is characterized as an immunological cold tumor with low T-cell infiltration, which could explain the disappointing results of clinical trials investigating CI treatment in MPM. Currently, many other therapeutic approaches, such as cellular therapies and cancer vaccines are investigated that could induce a tumor-specific immune response and increase of the number of tumor-infiltrating lymphocytes. In this review we will discuss these novel treatment approaches for MPM.

Amrubicin in previously treated patients with malignant pleural mesothelioma: A phase II study

Background

The aim of this study was to assess the efficacy and safety of amrubicin for previously treated malignant pleural mesothelioma.

Methods

The eligibility criteria were: previously treated unresectable malignant pleural mesothelioma; performance status 0–1; age ≤ 75; adequate hematological, hepatic, and renal function. The patients were injected with 35 mg/m² amrubicin on days one, two, and three every 3–4 weeks. The planned number of patients was 32.

Results

The study was terminated due to delay in enrollment and 10 patients were subsequently enrolled (nine males and one female; median age 67 [range 49–73]), of which four had epithelioid tumors, three had sarcomatoid tumors and three had biphasic tumors, respectively. According to the International Mesothelioma Interest Group (IMIG), one, four, and four patients had stage II, III, and IV, respectively, and one had postoperative recurrence. There was one (10%) partial response, four (40%) had stable disease, and five (50%) patients exhibited disease progression. The overall response and disease control rates were 10% (95% CI: 0.3–44.5%) and 60% (95% CI: 26.2–87.8%), respectively. The median progression‐free survival time was 1.6 months. The median overall survival time was 6.6 months, and the one‐, two‐, and three‐year survival rates were 23%, 23%, and 0%, respectively. The observed grade 3 or 4 toxicities included neutropenia in six (60%) patients; leukopenia in five (50%) patients; and febrile neutropenia, thrombocytopenia, anemia, and pneumonia in one (10%) patient each.

Conclusions

There was not enough data to evaluate the efficacy because the study was terminated early. However, amrubicin showed limited activity and

acceptable toxicities when used in previously treated malignant pleural mesothelioma patients.

Tumour cell PD-L1 expression is prognostic in patients with malignant pleural effusion: the impact of C-reactive protein and immune-checkpoint inhibition

Malignant pleural effusion (MPE) confers dismal prognosis and has limited treatment options. While immune-checkpoint inhibition (ICI) proved clinical efficacy in a variety of malignancies, data on the prognostic role of PD-L1 in MPE is scarce. We retrospectively studied PD-L1 tumour proportion score and Ki-67 index in pleural biopsies or cytologies from 123 patients (69 lung cancer, 25 mesothelioma, and 29 extrathoracic primary malignancies). Additionally, the impact of C-reactive protein (CRP) and platelet count was also analysed. Median overall survival (OS) after MPE diagnosis was 9 months. Patients with PD-L1 positive tumours (≥1%) had significantly shorter OS than patients with negative PD-L1 status (p = 0.031). CRP and Ki-67 index were also prognostic and remained independent prognosticators after multivariate analysis. Interestingly, Ki-67 index and CRP influenced the prognostic power of PD-L1. Finally, patients receiving ICI tended to have a longer median OS and CRP - but not PD-L1 - was a significant prognosticator in this subgroup. In summary, histological and circulating biomarkers should also be taken into account as potential biomarkers in ICI therapy and they may have an impact on the prognostic power of PD-L1. Our findings might help personalizing immune-checkpoint inhibition for patients with MPE and warrant further prospective validation.

Emerging Treatments for Malignant Pleural Mesothelioma: Where Are We Heading?

Malignant pleural mesothelioma (MPM) is an uncommon but aggressive and treatment resistant neoplasm with low survival rates. In the last years we assisted to an exponential growth in the appreciation of mesothelioma pathobiology, leading several new treatments to be investigated both in the early stage of the disease and in the advanced setting. In particular, expectations are now high that immunotherapy will have a leading role in the next years. However, caution is required as results from phase II studies in MPM were often not replicated in larger, randomized, phase III trials. In this review, we describe the most promising emerging therapies for the treatment of MPM, discussing the biological rationale underlying their development as well as the issues surrounding clinical trial design and proper selection of patients for every treatment.

Immunotherapy in Malignant Pleural Mesothelioma

The only registered systemic treatment for malignant pleural mesothelioma (MPM) is platinum based chemotherapy combined with pemetrexed, with or without bevacizumab. Immunotherapy did seem active in small phase II trials. In this review, we will highlight the most important immunotherapy-based research performed and put a focus on the future of MPM. PD-(L)1 inhibitors show response rates between 10 and 29% in phase II trials, with a wide range in progression free (PFS) and overall survival (OS). However, single agent pembrolizumab was not superior to chemotherapy (gemcitabine or vinorelbine) in the recent published PROMISE-Meso trial in pre-treated patients. In small studies with CTLA-4 inhibitors there is evidence for response in some patients, but it fails to show a better PFS and OS compared to best supportive care in a randomized study. A combination of PD-(L)1 inhibitor with CTLA-4 inhibitor seem to have a similar response as PD-(L)1 monotherapy. The first results of combining durvalumab (PD-L1 blocking) with cisplatin-pemetrexed in the first line are promising. Another immune treatment is Dendritic Cell (DC) immunotherapy, which is recently tested in mesothelioma, shows remarkable anti-tumor activity in three clinical studies. The value of single agent checkpoint inhibitors is limited in MPM. There is an urgent need for biomarkers to select the optimal candidates for immunotherapy among MPM patients in terms of efficacy and tolerance. Results of combination checkpoint inhibitors with chemotherapy are awaiting.