Accelerated hemithoracic radiation followed by extrapleural pneumonectomy for malignant pleural mesothelioma

The Role of Surgery in Pleural Mesothelioma: A Journey through the Evidence, MARS 2 and Beyond

Pleural mesothelioma (PM) is a rare incurable disease, predominantly linked to asbestos exposure. Not only is diagnosis difficult, but treatment choices are often limited to systemic anti-cancer treatment with chemotherapy or immunotherapy. Surgery has been employed for decades, but its application has been fiercely debated despite some randomized controlled trials such as the recent Mesothelioma and Radical Surgery 2 (MARS 2) study. We provide a commentary on this controversial topic.

Radical hemithorax radiotherapy induces an increase in circulating PD-1+ T lymphocytes and in the soluble levels of PD-L1 in malignant pleural mesothelioma patients: a possible synergy with PD-1/PD-L1 targeting treatment?

Malignant Pleural Mesothelioma (MPM) is an aggressive tumor associated with asbestos exposure, characterized by a poor prognosis, managed with surgery, chemotherapy and radiotherapy. Recently, immunotherapy gives a survival advantage compared to chemotherapy, but limited to the non-epithelioid histotype, the rarest type. Radical hemithorax radiotherapy (RHRT) improves the Overall Survival (OS) of MPM patients, irrespective of histotype, and is able to induce immunomodulatory effects. In this study we aim to investigate changes in circulating T lymphocytes phenotype and activity, in MPM patients undergoing RHRT, to evaluate a possible therapeutic space for immunotherapy in this setting. To assess immunomodulatory effects of RHRT we evaluate peripheral blood samples of 35 MPM patients collected before treatment, at the end of RT, and 1 month later. We first notice that higher Lymphocyte-to-Monocyte Ratio (LMR) levels, before RT, are associated with an improved OS. The immune monitoring performed by ELISA assays reveals a significant increase in the serum levels of soluble PD-L1 (sPD-L1) and IFN-γ at the end of RHRT. Furthermore, the percentage of PD-1+ cells, evaluated by flow cytometry, significantly raise after RHRT in T cells, both CD4+ and CD8+. Also the proportion of proliferative cells is significantly expanded after RHRT in all T cell subtypes. After treatment we observe a significant increase in the number of patients showing WT-1 specific CD4+ T cells, measured by intracellular staining. The TCR repertoire analysis, investigated by Next Generation Sequencing, reveals an increased number of expanded T-cell clones after RHRT, and an association between TCR clonality and the percentage of proliferating cytotoxic T lymphocytes. The comparison of TCR sequences obtained in our cohort with those described in a literature cohort of MPM patients, reveals common entries, specific for MPM-associated antigens including WT-1. In this setting, pre-treatment levels of LMR seem to have a positive prognostic role, and RHRT would appear to induce immunomodulating effects, potential biomarkers for immunotherapy eligibility: i.e. increased PD-1+ T lymphocytes, proliferating T cells, expanded T cell clones and augmented levels of sPD-L1. These data suggest the design of a prospective study evaluating a maintenance immunotherapy after RHRT in MPM, even in the epithelioid histotype.

Impact of Neoadjuvant and Adjuvant Pleural Intensity-Modulated Radiotherapy in Multimodality Treatment for Malignant Pleural Mesothelioma

BACKGROUND

Few malignancies provoke as many controversies about treatment as pleural mesothelioma. There is limited experience with novel radiotherapy techniques worldwide in adjuvant and particularly in neoadjuvant settings within multimodality treatment. The objective of the current study was to investigate the long-term outcome of neoadjuvant and adjuvant pleural intensity-modulated radiotherapy (IMRT) combined with macroscopic complete resection with or without chemotherapy.

METHODS

We retrospectively analyzed a consecutive cohort of 59 patients who were diagnosed with pleural mesothelioma and underwent multimodality treatment including macroscopic complete resection and neoadjuvant or adjuvant IMRT between 2005 and 2019 at the Department of Thoracic Surgery, Medical University of Vienna, Austria.

RESULTS

In total, 59 patients (median age 59 years; IQR 54-66, male, n = 48; 81%) were included. Forty-seven patients underwent trimodality treatment consisting of induction chemotherapy, extrapleural pneumonectomy, and adjuvant IMRT. Novel neoadjuvant IMRT with (n = 9) or without (n = 3) chemotherapy followed by extrapleural pneumonectomy was performed in 12 patients. Median overall survival (OS) of all patients was 23.2 months (95% CI; 18.1-28.2) and 3- and 5-year survival rates were 33% and 28%, respectively. Survival was comparable between therapies including neoadjuvant versus adjuvant IMRT (median OS 17.5 vs. 24.0 months, p = 0.39).

CONCLUSIONS

Neoadjuvant pleural IMRT has been investigated as a novel treatment option for highly selected cases in pleural mesothelioma. Neoadjuvant IMRT was effective and safe in patients treated in a high-volume institution but showed no relevant survival benefit compared to adjuvant IMRT within multimodality treatment.

The International Association for the Study of Lung Cancer Mesothelioma Staging Project: Proposals for the "N" Descriptors in the Forthcoming Ninth Edition of the TNM Classification for Pleural Mesothelioma

INTRODUCTION

The International Association for the Study of Lung Cancer developed an international database to inform potential revisions in the ninth edition of the TNM classification of diffuse pleural mesothelioma (PM). This study analyzed the clinical and pathologic N categories to determine whether revisions were indicated relative to the eighth edition staging system.

METHODS

Of 7338 PM cases diagnosed from 2013 to 2022 and 3598 met all inclusion criteria for planned analyses. Data on 2836 patients without metastases were included in this study. Overall survival (OS) was measured from date of diagnosis. Patients were included regardless of whether they received neoadjuvant treatment. For the pathologic N analysis, patients who underwent resection (extrapleural pneumonectomy or pleurectomy/decortication) were included. N subgroups were analyzed and OS assessed by the Kaplan-Meier method.

RESULTS

The existing eighth edition N categories were performed adequately in the ninth edition data set. A median OS advantage was noted for clinical and pathologic N0 versus N1 patients: 23.2 versus 18.5 and 33.8 versus 25.0 months, respectively. Patients with resected pN0 had a 3-year OS of 48%. No difference in OS was noted for single- versus multiple-station nodal metastases. The number of nodal stations sampled at the time of resection was not associated with a difference in OS.

CONCLUSIONS

Data regarding clinical and pathologic N categories corroborate those used in the eighth edition. No changes in the N categories are recommended in the ninth edition of PM staging system.

Does mediastinal lymph node involvement influence the surgical outcome in malign pleural mesothelioma?

BACKGROUND

This study examined the effect of metastatic mediastinal lymph node involvement on the prognosis of patients with malignant pleural mesothelioma (MPM) who underwent extrapleural pneumonectomy (EPP) or extended pleurectomy (E/P) and also to assess the effect of metastatic mediastinal lymph node involvement on the prognosis of patients with MPM in these group of patients.

METHODS

This retrospective study included 84 patients with MPM (66 men [78.6%] and 18 women [21.4%]) who underwent EPP (n = 44) or E/P (n = 40) at our institution between January 2001 and July 2019. Survival analyses were performed according to histopathology, nodal status, and surgical approach.

RESULTS

In the EPP group, patients with T2-N2 status had a significantly better mean survival (17 ± 2.1 months) than patients with T3-N2 (7.3 ± 1.6 months) or T4-N2 (3.2 ± 1.1 months) status (p = .001). In the E/P group, patients with T2-N2 status had a mean survival of 18 ± 1.1 months, while patients with T3-N2 and T4-N2 status had mean survival durations of 6.6 ± 1.6 and 4.8 ± 1.2 months, respectively (p = .159). In both treatment groups, the survival rates of patients with epithelial tumors were better than those of patients with non-epithelial tumors, independent of N status. None of the patients with N2 disease survived until 5 years postoperatively.

CONCLUSION

In summary, our results suggested that mediastinal lymph node metastasis negatively influenced the prognosis of patients with T3 MPM, regardless of treatment by EPP or E/P. Under these circumstances, preoperative cervical mediastinoscopy or endobronchial ultrasound-guided transbronchial needle aspiration may be considered for patients with high-stage MPM who are scheduled for surgery with curative intent. In our study, N2 status was spotted as a significant factor affecting survival, nevertheless its significance in survival of pleural mesothelioma patients should be analyzed in multi-centered studies.

Role of radiotherapy in the management of rare solid thoracic tumors of the adults

Thoracic tumors include more than one hundred histopathological subtypes. Rare thoracic malignancies can be defined as representing less than 1% of all thoracic tumors. The European Rare Cancer Surveillance Project (RARECARE) identified rarity as an incidence less than 6 for 100,000 people, with significant difference of prevalence between them. Modalities of treatment for these pathologies include surgery, radiotherapy, and systemic therapies. In this article, we aim to discuss role and techniques of radiotherapy in management of rare solid thoracic tumors in adults, focusing on different anatomical locations such as lung parenchyma, mediastinum, vessels, chest wall and pleural cavity.

Pleurectomy and decortication are associated with better survival for bicavitary cytoreductive surgery for mesothelioma compared with extrapleural pneumonectomy

OBJECTIVES

Mesothelioma is a nearly uniformly fatal tumor. Multimodality therapy including cytoreductive surgery and chemotherapy is associated with long-term survival in some patients. Cytoreductive surgery for thoracic disease includes a lung-sparing operation called an "extended pleurectomy/decortication" or a lung-sacrificing surgery called an "extrapleural pneumonectomy." The benefit of cytoreductive surgery for bicavitary disease (chest and abdomen) is poorly understood. Our objective was to evaluate the long-term survivals for patients undergoing cytoreductive surgery for bicavitary disease and to determine whether any prognostic factors were associated with outcome.

METHODS

We reviewed our Institutional Review Board-approved, institutional, International Association for the Study of Lung Cancer Mesothelioma Staging Project database. Inclusion criteria were all patients who underwent cytoreductive surgery for bicavitary disease. Overall survival was calculated by Kaplan-Meier methodology. All International Association for the Study of Lung Cancer database elements were evaluated by univariable analysis.

RESULTS

From February 2014 to August 2021, 440 patients with mesothelioma were evaluated. Fourteen patients (3%) underwent cytoreductive surgery of both chest and abdomen as a planned 2-stage operation. Most patients (13/14; 93%) underwent chest surgery before abdomen surgery. For the entire cohort, the median overall survival was 33.6 months with a 5-year survival of 20%. Extended pleurectomy/decortication was associated with a better outcome compared with extrapleural pneumonectomy, with median overall survivals of 58.2 versus 13.5 months, respectively.

CONCLUSIONS

For a highly selected group of patients with bicavitary mesothelioma, long-term survival can be achieved with an aggressive, staged surgical approach. The patients who undergo extended pleurectomy/decortication with preservation of the lung appear to have more favorable outcomes compared with patients undergoing extrapleural pneumonectomy.

The Impact of Adjuvant Hemithoracic Radiation on Outcomes in Patients With Stage I-III Malignant Pleural Mesothelioma: A Dual Registry Analysis

BACKGROUND

The outcomes associated with receipt of adjuvant radiation in patients after surgery for MPM are poorly understood.

OBJECTIVE

The objective of this study was to use 2 registries to compare the outcomes of patients receiving adjuvant radiation or no radiation after definitive surgery for pathologic stage I-III MPM.

METHODS

Patients with resected pathologic stage I-III MPM were identified from the Duke University registry (1996-2016) and National Cancer Database (NCDB) (2004-2015). The primary outcome was overall survival. Propensity score-matched and landmark subgroup analyses were performed.

RESULTS

A total of 212 institutional and 1615 NCDB patients met criteria. In both cohorts, patients who underwent radiation were more likely to have margin-negative resection and more advanced pathologic stage. At a landmark time of 4.4 and 4.7 months from surgery, Duke [hazard ratio (HR) 1.14; 95% confidence interval (CI) 0.62-2.11] and NCDB patients (HR 0.97; 95% CI 0.81-1.17) who received adjuvant radiation did not experience improved survival compared to those who did not receive radiation in multivariable analysis. Duke patients who received radiation had similar incidence of recurrence and time to both overall recurrence and ipsilateral recurrence (HR 0.87; 95% CI 0.43-1.77) compared to those who did not. Duke patients experienced 100 grade 1/2, 21 grade 3/4, and one grade 5 toxicity events during radiation.

CONCLUSIONS

In this dual registry analysis of patients with resected stage I-III MPM, the receipt of adjuvant hemithoracic radiation was not associated with improved survival compared to no radiation.

Malignant Pleural Mesothelioma: Preliminary Toxicity Results of Adjuvant Radiotherapy Hypofractionation in a Prospective Trial (MESO-RT)

Malignant Pleural Mesothelioma (MPM) is a rare malignancy with an overall poor prognosis. The standard therapeutic strategy in early-stage disease is trimodality therapy. In this publication, we report the preliminary toxicity results of the first 20 patients treated with accelerated hypofractionated radiotherapy. Between July 2017 to June 2019, 20 MPM patients were enrolled and treated with accelerated hypofractionated radiotherapy using helical tomotherapy and intensity-modulated arc therapy. The prescription dose was 30 Gy in five daily fractions, while an inhomogeneous dose escalation to 40 Gy was prescribed based solely upon the presence of gross residual tumor. Only one case of G3 toxicity was reported, which was a bilateral pneumonitis that occurred two years after treatment probably due to superinfection. Median Time to Progression reached 18.2 months while one- and three-year Overall Survival rates were 85% (95% CI:60.4-94.9) and 49.5% (95% CI:26.5-68.9), respectively. Treatment of the intact lung with pleural intensity-modulated arc irradiation is a novel treatment strategy that appears to be safe, feasible, and without a high grade of lung toxicity. Survival rates and Time to Progression are encouraging.

A Phase 1 Safety Study of Avelumab Plus Stereotactic Body Radiation Therapy in Malignant Pleural Mesothelioma

Introduction

Single-agent monoclonal antibody therapy against programmed death-ligand 1 (PD-L1) has modest effects in malignant pleural mesothelioma. Radiation therapy can enhance the antitumor effects of immunotherapy. Nevertheless, the safety of combining anti-PD-L1 therapy with stereotactic body radiation therapy (SBRT) is unknown. We present the results of a phase 1 trial to evaluate the safety of the anti-PD-L1 antibody avelumab plus SBRT in patients with malignant pleural mesothelioma.

Methods

This was a single-arm, investigator-initiated trial in patients who progressed on prior chemotherapy. Avelumab was delivered every other week, and SBRT was delivered to one lesion in three to five fractions (minimum of 30 Gy) followed by continuation of avelumab up to 24 months or until disease progression. The primary end point of the study was safety on the basis of grade 3+ nonhematologic adverse events (AEs) within 3 months of SBRT.

Results

Thirteen assessable patients received a median of seven cycles (range: 2-26 cycles) of avelumab. There were 27 grade 1, 17 grade 2, four grade 3, and no grade 4 or 5 avelumab-related AEs. The most common were infusion-related allergic reactions (n = 6), anorexia or weight loss (n = 6), fatigue (n = 6), thyroid disorders (n = 5), diarrhea (n = 3), and myalgia or arthralgias (n = 3). There were 10 grade 1, four grade 2, one grade 3, and no grade 4 or 5 SBRT-related AEs. The most common were diarrhea (n = 3), chest pain/myalgia (n = 2), fatigue (n = 2), cough (n = 2), dyspnea (n = 2), and nausea/vomiting (n = 2).

Conclusions

Combination avelumab plus SBRT seems tolerable on the basis of the prespecified toxicity end points of the first stage of this Simon two-stage design phase 1 study.

New Era for Malignant Pleural Mesothelioma: Updates on Therapeutic Options

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

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.

Malignant Pleural Mesothelioma Nodal Status: Where Are We at?

Due to the lack of both prospective trial and high-volume retrospective studies, the management of clinical N+ malignant pleural mesothelioma (MPM) patients remains highly debated. Node positive patients show poor survival compared with node-negative ones; thus, lymph node staging appears crucial in determining treatment strategy. Notwithstanding the improvement in pre-treatment staging and the update on lymph node classification in the 8th edition of TNM, several open controversies remain on N parameter. How should we stage suspected N+ patients? How should we treat node positive patients? Which is the definition of a “resectable patient”? Is the site or the number the main prognostic factor for node positive patients? The aim of our narrative review is to analyse the existing relevant literature on lymph node status in MPM.

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

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

Management of Advanced Pleural Mesothelioma-At the Crossroads

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

GOECP/SEOR clinical guidelines on radiotherapy for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare tumor with poor prognosis and rising incidence. Palliative care is common in MPM as radical treatment with curative intent is often not possible due to metastasis or extensive locoregional involvement. Numerous therapeutic advances have been made in recent years, including the use of less aggressive surgical techniques associated with lower morbidity and mortality (e.g., pleurectomy/decortication), technological advancements in the field of radiotherapy (intensity-modulated radiotherapy, image-guided radiotherapy, stereotactic body radiotherapy, proton therapy), and developments in systemic therapies (chemotherapy and immunotherapy). These improvements have had as yet only a modest effect on local control and survival. Advances in the management of MPM and standardization of care are hampered by the evidence to date, limited by high heterogeneity among studies and small sample sizes. In this clinical guideline prepared by the oncological group for the study of lung cancer of the Spanish Society of Radiation Oncology, we review clinical, histologic, and therapeutic aspects of MPM, with a particular focus on all aspects relating to radiotherapy, including the current evidence base, associations with chemotherapy and surgery, treatment volumes and planning, technological advances, and reradiation.

Malignant pleural mesothelioma: Comparison of surgery-based trimodality therapy to medical therapy at two tertiary academic institutions

OBJECTIVES

Medical management based on palliative chemotherapy is currently the standard of care in malignant pleural mesothelioma (MPM). Median survival of 12-16 months has been reported with modern chemotherapy regimens with or without anti-angiogenic agents. Multimodality therapy incorporating cytoreductive surgery, systemic chemotherapy and radiotherapy has been offered for years to fit patients with early-stage disease, but its role remains debated. Our objective was to compare overall survival in patients offered multimodality therapy in a specialized clinic setting in London, UK to that of patients offered exclusively medical treatment at another academic institution in Quebec, Canada.

MATERIALS AND METHODS

We retrospectively compared the survival rates of 2 separate cohorts of patients treated consecutively: Cohort 1 (n = 106) received multimodality therapy including systemic chemotherapy, extended pleurectomy/decortication (P/D) and prophylactic radiotherapy in London (United Kingdom) between 2009 and 2016, while Cohort 2 (n = 98) received medical treatment at the Quebec Heart and Lung Institute (Canada) during the same period.

RESULTS

In Cohort 1, all patients but two completed trimodality therapy. In cohort 2, 51 % received palliative care only and 40 % received systemic chemotherapy. Median survival was 32 months vs 10 months in Cohort 1 and Cohort 2, respectively (hazard ratio with age, gender, pathology and TNM staging as covariates: 3.81; 95 % CI: 2.67-5.45; p < 0.0001). Similar results were obtained in sensitivity analyses, after excluding those who received best supportive care only and in a propensity score-matched analysis.

CONCLUSION

Aggressive therapy of MPM using cancer-directed surgery, systemic chemotherapy and prophylactic radiotherapy may provide a significant survival benefit in selected patients.

SEOM clinical guidelines for the treatment of malignant pleural mesothelioma (2020)

Mesothelioma is a rare and aggressive tumour with dismal prognosis arising in the pleura and associated with asbestos exposure. Its incidence is on the rise worldwide. In selected patients with early-stage MPM, a maximal surgical cytoreduction in combination with additional antitumour treatment may be considered in selected patients assessed by a multidisciplinary tumor board. In patients with unresectable or advanced MPM, chemotherapy with platinum plus pemetrexed is the standard of care. Currently, no standard salvage therapy has been approved yet, but second-line chemotherapy with vinorelbine or gemcitabine is commonly used. Novel therapeutic approaches based on dual immunotherapy or chemotherapy plus immunotherapy demonstrated promising survival benefit and will probably be incorporated in the future.

Prognostic impact of PD-1 and PD-L1 expression in malignant pleural mesothelioma: an international multicenter study

BACKGROUND

Programmed cell death 1/programmed death ligand 1 (PD-1/PD-L1) immune-checkpoint blockade is a promising new therapeutic strategy in cancer. However, expression patterns and prognostic significance of PD-L1 and PD-1 are still controversial in human malignant pleural mesothelioma (MPM).

METHODS

Formalin-fixed paraffin-embedded (FFPE) tumor samples from 203 MPM patients receiving standard treatment without immunotherapy were collected from 5 European centers. PD-L1 and PD-1 expression of tumor cells (TCs) and tumor-infiltrating lymphocytes (TILs) were measured by immunohistochemistry and correlated with clinical parameters and long-term outcome.

RESULTS

High (>10%) PD-L1 TC and PD-1 TILs expressions were found in 18 (8%) and 39 (24%) patients, respectively. PD-L1 was rarely expressed by TILs [≥1%, n=13 (8%); >10%, n=1]. No significant associations were found between the PD-L1 or PD-1 expression of TCs or TILs and clinicopathological parameters such as stage or histological subtype. Notably, patients with high (>10%) TC-specific PD-L1 expression exhibited significantly worse median overall survival (OS) (6.3 vs. 15.1 months of those with low TC PD-L1 expression; HR: 2.51, P<0.001). In multivariate cox regression analysis adjusted for clinical parameters, high TC PD-L1 expression (>10%) proved to be an independent negative prognostic factor for OS (HR: 2.486, P=0.005). There was no significant correlation between PD-L1 or PD-1 expression of TILs and OS.

CONCLUSIONS

In this multicenter cohort study, we demonstrate that high (>10%) PD-L1 expression of TCs independently predicts worse OS in MPM. Further studies are warranted to investigate the value of PD-L1/PD-1 expression as a marker for treatment response in MPM patients receiving immunotherapy.

Controversies in the role of radiotherapy in pleural mesothelioma

Malignant pleural mesothelioma is an uncommon thoracic cancer with a relatively poor outcome, which has only seen modest improvements when compared to non-small cell lung cancer. The mainstays of treatment have been surgery and systemic therapy, with radiation reserved for palliation or as an adjunct. However, there is re-emergent interest in the use of radiotherapy in the treatment of mesothelioma, given recent technical advances in radiotherapy delivery which permit increased treatment accuracy. This overview article reviews the radiobiology of the mesothelioma and whether or not mesothelioma is an inherently radioresistant cancer and the potential impact that hypofractionation may have on different histological subtypes in mesothelioma. This overview also considers the role of radiation in palliation, as adjunct to surgical resection and as adjunct to pleural tract procedures. In particular we review the growing evidence that pleural tract or port site adjuvant radiotherapy provides no clinical benefit. This overview will also consider potential emerging therapeutic strategies such as pre-operative short course hypofractionated radiotherapy. The role of novel radiotherapy techniques such as stereotactic ablative radiotherapy, image guided radiotherapy, proton therapy and the potential role of radiotherapy as an immune stimulating agent in combination of immunotherapy, will also be discussed. Finally, given the many unanswered questions, this review discusses some of the emerging and ongoing clinical trials of radiotherapy in the treatment of mesothelioma.

Follow-up of Soluble Mesothelin-Related Protein Levels in Participants With Asbestos-Related Disorders

Background

Asbestos exposure is associated with the development of the cancer malignant mesothelioma (MM). Measurement of soluble mesothelin-related protein (SMRP) has been suggested as a method for detection of MM in its early stages. We prospectively examined SMRP levels in participants with asbestos exposure who are a group at a high risk of development of MM.

Methods

This study was a follow-up of our cohort of 322 asbestos-exposed participants. No further participants developed MM or malignancy over the study period. Mean follow-up time was 22.9 months.

Results

Mean (standard deviation) SMRP levels at baseline and follow-up were 0.94 (0.79) and 0.91 (0.86) nmol/L (p = 0.1033), respectively. Mean SMRP levels of the healthy individuals exposed to asbestos at baseline was significantly lower than those of participants with asbestosis and pleural plaques alone; similar patterns were found on follow-up measurements. There was a statistically significant effect of age on serial SMRP measurements. Our study confirms higher levels in participants with nonmalignant asbestos-related disorders. Levels decreased in asbestos-related disorders other than asbestosis, where a small increase was observed. We did not detect any further cases of malignancy.

Conclusion

Monitoring programs for early detection of MM need to take into account increased SMRP levels found in benign asbestos-related diseases.

Diagnostic Laparoscopy Improves Staging of Malignant Pleural Mesothelioma With Routine Positron Emission Tomography Imaging

BACKGROUND

With a multimodal treatment strategy, cytoreductive surgery extends survival in malignant pleural mesothelioma. Improving the accuracy of staging can refine patient selection. Our objective was to determine whether diagnostic laparoscopy (DL) improves staging for patients with malignant pleural mesothelioma with the routine use of positron emission tomography (PET).

METHODS

We performed a retrospective review of our prospectively maintained database from February 2014 to May 2019. Inclusion criteria were patients who had disease in the chest that was deemed potentially resectable by radiographic criteria and who underwent DL as part of the staging evaluation before surgery.

RESULTS

Of 187 patients (71% men, 80% epithelial) who underwent DL during staging, 76% proceeded to surgery; 22% were unresectable at exploratory thoracotomy and 78% underwent resection (pleurectomy and decortication, 68%; extrapleural pneumonectomy, 32%). Also, 89% had a PET computed tomography (CT), and 11% had a preoperative CT without PET. DL revealed peritoneal disease in 17%. Among patients with pathologically proven disease at DL, 77% had negative PET-CT imaging. Based on the pathologic findings at DL the sensitivity, specificity, positive predictive value, and negative predictive value of PET-CT were 23%, 78%, 17%, and 83%, respectively. The accuracy of PET-CT was 68%.

CONCLUSIONS

PET-CT has low sensitivity and diagnostic accuracy to identify peritoneal disease in malignant pleural mesothelioma. DL as part of the preoperative staging defines an important subset of patients with bicavitary disease. We recommend DL as a component of staging before surgery.

Trimodality treatment in malignant pleural mesothelioma - Ordeal or real deal?

BACKGROUND

Management of MPM is complex and controversial as there is a paucity of good quality evidence. We report the toxicity and outcomes in patients who received trimodality treatment for non-metastatic MPM at our institution.

METHODS & MATERIALS

We reviewed the electronic medical records of surgically managed MPM patients at our institution in the last decade. Dosimetric parameters of target volume and organs at risk were documented by the treatment planning workstation. SPSS was used for statistical analysis.

RESULTS

Between January 2008 and October 2018, 21 patients underwent surgery for MPM - all but 2 patients underwent extra-pleural pneumonectomy (EPP); epithelioid MPM was the most common histology. All patients, except 2, received neoadjuvant Pemetrexed/platinum doublet chemotherapy. Fourteen patients received adjuvant hemithoracic RT; ten patients were treated with a conformal technique at our institute and dosimetric data was available for analysis. Average time to start RT after surgery was 51 days (range 32-82 days). All patients were treated with a conformal technique using IMRT/VMAT to a dose of 45Gy in 25 fractions. Mean overall RT duration was 35 days (range 30-42 days). Grade I/II Pneumonitis was seen in 4 patients. One patient developed grade III acute lung toxicity unrelated to RT. At a median follow up of 25 months, 8 patients had died, of whom six died due to the disease and two died in the immediate post op period. Two-year DFS and OS were 58% and 73%, respectively.

CONCLUSION

In spite of the extensive surgery and complex hemithoracic RT, we demonstrated excellent dosimetry, toxicity profile and favorable outcomes in non-metastatic MPM.

Radiation Therapy for Malignant Pleural Mesothelioma

The treatment of malignant pleural mesothelioma with radiation therapy has always been a technical challenge. For many years, radiation therapy was delivered after extrapleural pneumonectomy with acceptable results. As the utilization of pleurectomy/decortication increased, techniques, such as pleural intensity-modulated radiation therapy (IMRT) have been introduced. The experience with these techniques have grown and multiple trials using IMRT, both in the setting of extrapleural pneumonectomy or pleurectomy, are being conducted to assess its effectiveness.

Foxp3+ Regulatory T Cell Depletion after Nonablative Oligofractionated Irradiation Boosts the Abscopal Effects in Murine Malignant Mesothelioma

Increasing evidence indicates that local hypofractionated radiotherapy (LRT) can elicit both immunogenic and immunosuppressive local and systemic immune responses. We thus hypothesized that blockade of LRT-induced immunosuppressive responses could augment the antitumor effects and induce an abscopal response. In this study, we found that the upregulation of Foxp3⁺ regulatory T cells (Tregs) in the mesothelioma tumor microenvironment after nonablative oligofractionated irradiation significantly limited the success of irradiation. Using DEREG mice, which allow conditional and efficient depletion of Foxp3⁺ Tregs by diphtheria toxin injection, we observed that transient Foxp3⁺ Treg depletion immediately after nonablative oligofractionated irradiation provided synergistic local control and biased the T cell repertoire toward central and effector memory T cells, resulting in long-term cure. Furthermore, this combination therapy showed significant abscopal effect on the nonirradiated tumors in a concomitant model of mesothelioma through systemic activation of cytotoxic T cells and enhanced production of IFN-γ and granzyme B. Although local control was preserved with one fraction of nonablative irradiation, three fractions were required to generate the abscopal effect. PD-1 and CTLA-4 were upregulated on tumor-infiltrating CD4⁺ and CD8⁺ T cells in irradiated and nonirradiated tumors, suggesting that immune checkpoint inhibitors could be beneficial after LRT and Foxp3⁺ Treg depletion. Our findings are applicable to the strategy of immuno-radiotherapy for generating optimal antitumor immune responses in the clinical setting. Targeting Tregs immediately after a short course of irradiation could have a major impact on the local response to irradiation and its abscopal effect.

Updates in Staging and Management of Malignant Pleural Mesothelioma

While without treatment, malignant pleural mesothelioma (MPM) confers poor survival, cancer-directed surgery as part of multimodality treatment is associated with a 15% 5-year survival. Extrapleural pneumonectomy (EPP) and radical or extended pleurectomy/decortication (P/D) are the 2 types of resection performed in this context. Preoperative staging is critical to patient selection for surgery; P/D is recommended over EPP in most cases. Adjuvant therapy with intraoperative platforms, traditional chemotherapy, hemithoracic radiotherapy resection, and new immunotherapy agents are instrumental in achieving durable long-term results. We outline the latest understanding of disease staging and describe the current state of literature and practice.

Consensus Statement on Proton Therapy in Mesothelioma

PURPOSE

Radiation therapy for mesothelioma remains challenging, as normal tissue toxicity limits the amount of radiation that can be safely delivered to the pleural surfaces, especially radiation dose to the contralateral lung. The physical properties of proton therapy result in better sparing of normal tissues when treating the pleura, both in the postpneumonectomy setting and the lung-intact setting. Compared with photon radiation, there are dramatic reductions in dose to the contralateral lung, heart, liver, kidneys, and stomach. However, the tissue heterogeneity in the thorax, organ motion, and potential for changing anatomy during the treatment course all present challenges to optimal irradiation with protons.

METHODS

The clinical data underlying proton therapy in mesothelioma are reviewed here, including indications, advantages, and limitations.

RESULTS

The Particle Therapy Cooperative Group Thoracic Subcommittee task group provides specific guidelines for the use of proton therapy for mesothelioma.

CONCLUSIONS

This consensus report can be used to guide clinical practice, insurance approval, and future research.

Surgery for Mesothelioma After Radiation Therapy (SMART); A Single Institution Experience

Background: The optimal treatment sequence for localized malignant pleural mesothelioma (MPM) is controversial. We aimed to assess outcomes and toxicities of treating localized MPM with neoadjuvant radiation therapy (RT) followed by extrapleural pneumonectomy (EPP). Methods: Patients were enrolled on an institutional protocol of surgery for mesothelioma after radiation therapy (SMART) between June 2016 and May 2017. Eligible patients were adults with MPM localized to the ipsilateral pleura. Patients underwent staging with PET/CT, pleuroscopy, bronchoscopy/EBUS, mediastinoscopy, and laparoscopy. Five fractions of RT were delivered using intensity modulated radiation therapy (IMRT), with 30 Gy delivered to gross disease and 25 Gy to the entire pleura. EPP was performed 4-10 days following completion of RT. Results: Five patients were treated on protocol. Median age was 62 years (range 36-66). Histology was epithelioid on initial biopsy in all patients, but one was found to have biphasic histology after surgery. Three patients had surgeon-assessed gross total resection, and two had gross residual disease. While all patients were clinically node negative by pretreatment staging, three had positive nodal disease at surgery. Patients were hospitalized for a median 24 days (range 5-69) following surgery. Two patients developed empyema, one of whom developed respiratory failure and subsequently renal failure requiring dialysis, while the other required multiple surgical debridements. Two patients developed atrial fibrillation with rapid ventricular response after surgery, one of whom developed acute respiratory distress requiring intubation and tracheostomy. At last follow-up, one patient died at 1.4 years after local and distant progression, two were alive with local and distant progression, and the remaining two were alive without evidence of disease at 0.1 and 2.7 years. Median time to progression was 9 months. Three patients received salvage chemotherapy. Conclusions: SMART provided promising oncologic outcomes at the cost of significant treatment related morbidity. Due to the significant treatment associated morbidity and favorable treatment alternatives, we have not broadly adopted SMART at our institution.

Surgery for pleural mesothelioma, when it is indicated and why: arguments against surgery for malignant pleural mesothelioma

Extrapleural pneumonectomy (EPP) and pleurectomy decortication (PD) are radical operations for malignant pleural mesothelioma (MPM) that remain controversial among thoracic surgeons. There is a lack of randomized evidence to support a survival benefit when major surgical resection is included in multi-modality treatment regimens. Current data from retrospective single institution reviews and prospective trials such as the Surgery for Mesothelioma After Radiation Therapy (SMART) trial are limited by biased patient selection to include only the healthiest patients with most limited disease burden. This patient population predictably has relatively longer survival times than patients with inoperable advanced disease. The only randomized trial to date that has objectively evaluated the true benefit of surgical resection was the Mesothelioma and Radical Surgery (MARS) trial which actually showed shorter survival times among patients who underwent EPP compared with those treated medically. Critics of the MARS trial cite a high perioperative mortality rate for driving these results, however a similar trial has never been repeated to refute the MARS trial results. Finally, it is relevant to consider the high mortality and morbidity rates associated with major operations when recommending these interventions to MPM patients. There is a growing body of literature that identifies patients who clearly obtain no benefit from surgery including those with sarcomatoid or biphasic histology, nodal disease, elevated CRP, elevated platelets and advanced age. Surgery in MPM has risks and is of questionable benefit with outcomes data biased by patient selection of those who will have longer overall survival times regardless of treatment.

Malignant Pleural Mesothelioma: State-of-the-Art on Current Therapies and Promises for the Future

Malignant pleural mesothelioma (MPM) is a rare, aggressive cancer of the pleural surface associated with asbestos exposure. The median survival of MPM patients is a mere 8-14 months, and there are few biomarkers and no cure available. It is hoped that, eventually, the incidence of MPM will drop and remain low and constant, given that most nations have banned the use of asbestos, but in the meantime, the incidence in Europe is still growing. The exact molecular mechanisms that explain the carcinogenicity of asbestos are not known. Standard therapeutic strategies for MPM include surgery, often coupled with chemotherapy and/or radiotherapy, in a small percentage of eligible patients and chemotherapy in tumors considered unresectable with or without adjuvant radiotherapy. In recent years, several new therapeutic avenues are being explored. These include angiogenesis inhibitors, synthetic lethal treatment, miRNA replacement, oncoviral therapies, and the fast-growing field of immunotherapy alone or in combination with chemotherapy. Of particular promise are the multiple options offered by immunotherapy: immune checkpoint inhibitors, tumor vaccines, and therapies taking advantage of tumor-specific antigens, such as specific therapeutic antibodies or advanced cell-based therapies exemplified by the CAR-T cells. This review comprehensively presents both old and new therapeutic options in MPM, focusing on the results of the numerous recent and on-going clinical trials in the field, including the latest data presented at international meetings (AACR, ASCO, and ESMO) this year, and concludes that more work has to be done in the framework of tailored therapies to identify reliable targets and novel biomarkers to impact MPM management.

The phytohormone forchlorfenuron decreases viability and proliferation of malignant mesothelioma cells in vitro and in vivo

Malignant mesothelioma (MM) is one of the most aggressive cancer types with a patient’s life expectancy of typically less than one year upon diagnosis. The urgency of finding novel therapeutic approaches to treat mesothelioma is evident. Here we tested the effect of the plant-growth regulator forchlorfenuron (FCF), an inhibitor of septin function(s) in mammalian cells, on the viability and proliferation of MM cell lines, as well as other tumor cell lines derived from lung, prostate, colon, ovary, cervix and breast. Exposure to FCF strongly inhibited proliferation of human and mouse (most efficiently epithelioid) MM cells and all other tumor cells in a concentration-dependent manner and led to cell cycle arrest and cell death. The role of septin 7 (SEPT7), a presumably essential target of FCF in MM cells was confirmed by an shRNA strategy. FCF was robustly inhibiting tumor cell growth in vitro at low micromolar (IC₅₀: ≈20-60µM) concentrations and more promisingly also in vivo. Initial experiments with FCF analogous revealed the importance of FCF’s chloride group for efficient cell growth inhibition. FCF’s rather low systemic toxicity might warrant for an extended search for other related and possibly more potent FCF analogues to target MM and putatively other septin-dependent tumors.

Preoperative prediction of unresectability in malignant pleural mesothelioma

OBJECTIVE

Diffuse chest wall invasion (DCWI) is a common finding in patients undergoing intended resection for malignant pleural mesothelioma. We sought to determine the incidence and preoperative predictors of this finding, and to test our anecdotal impression that contraction of the ipsilateral hemithorax is associated with DCWI.

METHODS

This was a single-institution retrospective study of 170 patients undergoing intended macroscopic complete resection for malignant pleural mesothelioma from 2014-2018. A novel metric of thoracic cage volume was calculated by preoperative chest computed tomography. Univariable analyses were performed to determine associations of preoperative variables with DCWI.

RESULTS

Macroscopic complete resection was achieved by pleurectomy/decortication in 104 patients (61%) and by extrapleural pneumonectomy in 39 patients (23%). Unresectable disease was discovered at thoracotomy in 27 (16%) of patients; 24 (14%) by DCWI and 3 (2%) by intrathoracic organ invasion. In univariable analysis, decreased ipsilateral thoracic cage volume demonstrated the strongest association with unresectability by DCWI (P = .009) with >5% decrease in thoracic cage volume representing the optimal cutoff (P = .014; area under the curve, 0.67). Other preoperative variables associated with DCWI included preoperative chest pain requiring opioids (P = .028), prior pleurodesis (P = .036), decreased forced vital capacity (P = .023), decreased ipsilateral lung perfusion by ventilation/perfusion lung scan (P = .007), and magnetic resonance imaging findings of chest wall invasion (P = .035).

CONCLUSIONS

Preoperative identification of DCWI will avoid unnecessary thoracotomy and accelerate initiation of nonsurgical therapy in malignant pleural mesothelioma. Our data suggest that contraction of thoracic cage volume has merit in predicting malignant pleural mesothelioma unresectability and should be validated in prospective studies.

Extrapleural pneumonectomies for pleural mesothelioma

Introduction: Malignant pleural mesothelioma (MPM) is a fatal malignancy for which there is no definitive cure. The most effective multimodality treatment in prolonging survival is still matter of debate. Surgery remains one of the cornerstones in the multimodality therapy for MPM. Extra-pleural pneumonectomy and pleurectomy/decortication are the two main curative-intent procedures; however, the superiority of one technique over the other is still debated. This review aims to assess short- and long-term results of extrapleural pneumonectomy for MPM.Areas covered: This article focuses on the role of extrapleural pneumonectomy in MPM. A systematic review was performed by using electronic databases to identify studies that included patients treated by this procedure for MPM. Endpoints included overall survival, disease-free survival, recurrence rate, perioperative mortality, and morbidity.Expert commentary: This paper offers an overview of the results that are currently obtained in patients undergoing extrapleural pneumonectomy for MPM. The benefit of surgical treatments in MPM is still debated and its primary goal should be the achievement of a macroscopic complete resection. Several alternative multimodality protocols exist, with specific advantages and drawbacks; therefore, individualization of care for each patient is fundamental. The complexity of the surgical treatment mandates that patients be referred to specialized centers.

Prognostic influence of tumor microenvironment after hypofractionated radiation and surgery for mesothelioma

OBJECTIVE

Cytotoxic CD8+ tumor infiltrating lymphocytes (TILs) can contribute to the benefit of hypofractionated radiation, but programmed cell death pathways (programmed cell death 1 and programmed cell death ligand 1 [PD-1/PD-L1]) may provide a mechanism of tumor immune escape. We therefore reviewed the influence of PD-1/PD-L1 and CD8+ TILs on survival after accelerated hypofractionated hemithoracic radiation followed by extrapleural pneumonectomy for malignant pleural mesothelioma (MPM).

METHODS

Sixty-nine consecutive patients undergoing the protocol of Surgery for Mesothelioma after Radiation Therapy (SMART) between November 2008 and February 2016 were analyzed for the presence of PD-L1 on tumor cells, PD-1 on inflammatory cells, and CD8+ TILs. Comparison was made with a cohort of patients undergoing extrapleural pneumonectomy after induction chemotherapy (n = 14) and no induction (n = 2) between March 2005 and October 2008. PD-L1 expression on tumor cells ≥1% was considered positive. CD8+ TILs and PD-1 expression were scored as a percentage of positive cells.

RESULTS

PD-L1 was negative in 75% of MPM after completion of SMART. CD8+ TILs ranged between 0.24% and 8.47% (median 2%). CD8+ TILs ≥2% was associated with significantly better survival in epithelioid MPM (median survival 3.7 years vs 2.3 years in CD8+ TILs <2%; P = .02). PD-L1 positivity was associated with worse survival in biphasic MPM (median survival, 0.4 years vs 1.5 years in biphasic PD-L1 negative tumors; P = .07) after SMART. Multivariate analysis demonstrated that epithelioid MPM, nodal disease, and CD8+ TILs were independent predictors of survival after SMART.

CONCLUSIONS

The influence of tumor microenvironment on survival differs between epithelioid and nonepithelioid MPM. CD8+ TILs is an independent factor associated with better survival in epithelioid MPM treated with SMART.

Approved and emerging treatments of malignant pleural mesothelioma in elderly patients

Introduction: Malignant pleural mesothelioma (MPM) is a rare neoplasm with asbestos exposure as the dominant etiologic agent. Owing to the long latent period following exposure, MPM is often diagnosed late in life. Despite this, elderly patients are under-represented in clinical trials. To date, data regarding the tolerability and efficacy of anticancer treatments for elderly patients affected by MPM are still lacking.Areas covered: The current state-of-the-art of approved treatments employed in the treatment of MPM elderly patients is reviewed and discussed, with a look to emerging therapies. A structured search of bibliographic databases for peer-reviewed research literature and of main meeting abstracts using a focused review question was undertaken.Expert opinion: Even though the median age of MPM patients enrolled in the most recent experimental trials is increasing, no specific analysis has been reported so far in the elderly. Moreover, no data are available for the 'oldest of the elderly' (>75 years). Treatment of elderly patients with MPM is one of the major challenges to the clinician. There is a clear need of large, well-conducted retrospective studies and above all of prospective investigations in this patient population, both in the first-and in the second-line setting.

Scientific Advances and New Frontiers in Mesothelioma Therapeutics

Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer that arises from the mesothelial surface of the pleural and peritoneal cavities, the pericardium, and rarely, the tunica vaginalis. The incidence of MPM is expected to increase worldwide in the next two decades. However, even with the use of multimodality treatment, MPM remains challenging to treat, with a 5-year survival rate of less than 5%. The International Association for the Study of Lung Cancer has gathered experts in different areas of mesothelioma research and management to summarize the most significant scientific advances and new frontiers related to mesothelioma therapeutics.

The Use of Radiation Therapy for the Treatment of Malignant Pleural Mesothelioma: Expert Opinion from the National Cancer Institute Thoracic Malignancy Steering Committee, International Association for the Study of Lung Cancer, and Mesothelioma Applied Research Foundation

INTRODUCTION

Detailed guidelines regarding the use of radiation therapy for malignant pleural mesothelioma (MPM) are currently lacking because of the rarity of the disease, the wide spectrum of clinical presentations, and the paucity of high-level data on individual treatment approaches.

METHODS

In March 2017, a multidisciplinary meeting of mesothelioma experts was cosponsored by the U.S. National Cancer Institute, International Association for the Study of Lung Cancer Research, and Mesothelioma Applied Research Foundation. Among the outcomes of this conference was the foundation of detailed, multidisciplinary consensus guidelines.

RESULTS

Here we present consensus recommendations on the use of radiation therapy for MPM in three discrete scenarios: (1) hemithoracic radiation therapy to be used before or after extrapleural pneumonectomy; (2) hemithoracic radiation to be used as an adjuvant to lung-sparing procedures (i.e., without pneumonectomy); and (3) palliative radiation therapy for focal symptoms caused by the disease. We discuss appropriate simulation techniques, treatment volumes, dose fractionation regimens, and normal tissue constraints. We also assess the role of particle beam therapy, specifically, proton beam therapy, for MPM.

CONCLUSION

The recommendations provided in this consensus statement should serve as important guidelines for developing future clinical trials of treatment approaches for MPM.

Preliminary results of entire pleural intensity-modulated radiotherapy in a neoadjuvant setting for resectable malignant mesothelioma

Purpose

The purpose of this study is to evaluate the safety and efficacy of the multimodality treatment with neoadjuvant intensity-modulated radiotherapy (IMRT) for resectable clinical T1-3N0-1M0 malignant pleural mesothelioma (MPM).

Materials and Methods

A total of eleven patients who received neoadjuvant chemotherapy and radiotherapy between March 2016 and June 2018 were reviewed. Patients received 25 Gy in 5 fractions to entire ipsilateral hemithorax with helical tomotherapy.

Results

All of patients were men with a median age of 56 years. Epithelioid subtype was found in 10 patients. All patients received neoadjuvant chemotherapy with pemetrexed-cisplatin regimen. Ten patients (90.9%) completed 25 Gy/5 fractions and one (9.0%) completed 20 Gy/4 fractions of radiotherapy. IMRT was well tolerated with only one acute grade 3 radiation pneumonitis. Surgery was performed 1 week (median, 8 days; range, 1 to 15 days) after completing IMRT. Extrapleural pneumonectomy was performed in 4 patients (36.3%), extended pleurectomy/decortication in 2 (18.2%) and pleurectomy/decortications in 5 (63.6%). There was no grade 3+ surgical complication except two deaths after EPP in 1 month. Based on operative findings and pathologic staging, adjuvant chemotherapy was delivered in 7 patients (63.6%), and 2 (18.2%) were decided to add adjuvant radiotherapy. After a median follow-up of 14.6 months (range, 2.8 to 30 months), there were 3 local recurrence (33.3%) and 1 distant metastasis (11.1%).

Conclusion

Neoadjuvant entire pleural IMRT can be delivered with a favorable radiation complication. An optimal strategy has to be made in resectable MPM patients who would benefit from neoadjuvant radiation and surgery. Further studies are needed to look at long-term outcomes.

Updates in the diagnosis and treatment of malignant pleural mesothelioma

PURPOSE OF REVIEW

This review article describes current diagnostic and treatment modalities for malignant pleural mesothelioma (MPM).

RECENT FINDINGS

Few randomized trials in MPM have demonstrated improved survival with current therapies. A randomized trial of first-line chemotherapy with and without bevacizumab in unresectable MPM is the only randomized trial of a new treatment regimen to demonstrate a survival benefit since cisplatin with pemetrexed became the standard of care for unresectable MPM in 2003. Unfortunately, in unresectable MPM, first-line chemotherapy alone or in combination with bevacizumab has demonstrated only limited improvements in overall survival. Recently, in nonrandomized observational studies, multimodality treatments with chemotherapy, surgery, radiation, and novel therapies have been associated with prolonged survival in select patients. Currently, there are no FDA approved second-line therapies, and clinical trial enrollment is recommended for second-line treatment.

SUMMARY

MPM remains difficult to treat and has an overall poor prognosis despite current multimodality treatment. Thoracoscopy with multiple pleural biopsies can provide adequate tissue specimens for diagnostic testing to distinguish histologic MPM subtypes and perform molecular profiling, which influence prognosis and treatment options. In early clinical trials, immunotherapies and therapies directed against cancer-associated antigens and oncogenic alterations are emerging as promising future treatments.

The role of radiation treatment in pleural mesothelioma: Highlights of the 14th International Conference of the International mesothelioma interest group

Radiation remains an important component of mesothelioma treatment in 2018. Its use as a treatment modality continues to evolve as the technology for planning and delivery continues to improve. Use of radiation to improve local control in the involved hemithorax has been a common adjuvant treatment post extrapleural pneumonectomy for many years. Modern treatment options with advanced planning techniques including protons and intensity modulated radiation therapy lead to new potential options for treatment post lung-sparing surgery or in the unresectable setting. Presentations and discussions on the implementation of these strategies for palliation, treatment of oligometastatic recurrence or unresectable disease were the focus of a session dedicated to the role of radiation therapy at the 14^th International Conference of the International Mesothelioma Interest Group and are reviewed in this article. Preclinical data to better understand how to integrate radiation and the delivery of novel systemic therapy approached like check point inhibitors are also presented.

Endobronchial ultrasound-guided transbronchial needle aspiration mediastinal lymph node staging in malignant pleural mesothelioma

Background

Given poor survival of patients with malignant pleural mesothelioma (MPM) and extrapleural nodal metastasis, pre-operative mediastinal lymph node (LN) staging has been advocated. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) may be a useful pre-operative adjunct in patients with MPM. This study aims to assess performance of EBUS-TBNA for mediastinal LN staging in MPM.

Methods

A retrospective chart review of patients with diagnosis of MPM referred to the mesothelioma program at a tertiary Canadian cancer center between January 1, 2012 and December 31, 2014 who received mediastinal LN staging with EBUS-TBNA.

Results

Forty-eight patients were included. Average age was 70 years (range, 48-84 years). Mesothelioma subtypes were as follows: epithelioid 34/48 (70.8%), sarcomatoid 4/48 (8.3%), biphasic 7/48 (14.6%) and other 3/48 (6.3%). Stage distribution was as follows: I 18.8%, II 10.4%, III 47.9%, and IV 22.9%. On average 3.4 LNs were sampled per patient (range, 1-5). The mean short axis of a sampled LN was 6.8±3.8 mm. Rapid on Site Evaluation (ROSE) was available in 75.0% (36/48) of the assessments. Prevalence of N2/N3 disease was 35.4% (17/48). EBUS-TBNA sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy were: 16.7%, 100%, 100%, 68.8%, and 70.6%, respectively. EBUS-TBNA mediastinal LN staging prevented unnecessary surgery in 18.8% (9/48 patients) by detection of N2/N3 disease (8 patients) and metastatic secondary malignancy (1 patient). There were no EBUS-TBNA related complications.

Conclusions

EBUS-TBNA mediastinal LN staging may impact significantly management of patients with MPM by detecting mediastinal metastatic disease, therefore, preventing morbidity and mortality of surgical management.