Systematic review of response rates of sarcomatoid malignant pleural mesotheliomas in clinical trials

FK228 suppress the growth of human malignant pleural mesothelioma tumor independent to epithelioid or non-epithelioid histology

Human malignant pleural mesothelioma (hMPM) is an aggressive, rare disease with a poor prognosis. Histologically, MPM is categorized into epithelioid, biphasic, and sarcomatoid subtypes, with the epithelioid subtype generally displaying a better response to treatment. Conversely, effective therapies for the non-epithelioid subtypes are limited. This study aimed to investigate the potential role of FK228, a histone deacetylase inhibitor, in the suppression of hMPM tumor growth. We conducted a comprehensive analysis of the histological and molecular characteristics of two MPM cell lines, CRL-5820 (epithelioid) and CRL-5946 (non-epithelioid). CRL-5946 cells and non-epithelioid patient-derived xenografted mice exhibited heightened growth rates compared to those with epithelioid MPM. Both CRL-5946 cells and non-epithelioid mice displayed a poor response to cisplatin. However, FK228 markedly inhibited the growth of both epithelioid and non-epithelioid tumor cells in vitro and in vivo. Cell cycle analysis revealed FK228-induced G1/S and mitotic arrest in MPM cells. Caspase inhibitor experiments demonstrated that FK228-triggered apoptosis occurred via a caspase-dependent pathway in CRL-5946 but not in CRL-5820 cells. Additionally, a cytokine array analysis showed that FK228 reduced the release of growth factors, including platelet-derived and vascular endothelial growth factors, specifically in CRL-5946 cells. These results indicate that FK228 exhibits therapeutic potential in MPM by inducing cytotoxicity and modulating the tumor microenvironment, potentially benefiting both epithelioid and non-epithelioid subtypes.

The highly selective and oral phosphoinositide 3-kinase delta (PI3K-δ) inhibitor roginolisib induces apoptosis in mesothelioma cells and increases immune effector cell composition

Targeting aberrantly expressed kinases in malignant pleural mesothelioma (MPM) is a promising therapeutic strategy. We here investigated the effect of the novel and highly selective Phosphoinositide 3-kinase delta (PI3K-δ) inhibitor roginolisib (IOA-244) on MPM cells and on the immune cells in MPM microenvironment. To this aim, we analyzed the expression of PI3K-δ by immunohistochemistry in specimens from primary MPM, cell viability and death in three different MPM cell lines treated with roginolisib alone and in combination with ipatasertib (AKT inhibitor) and sapanisertib (mTOR inhibitor). In a co-culture model of patient-derived MPM cells, autologous peripheral blood mononuclear cells and fibroblasts, the tumor cell viability and changes in immune cell composition were investigated after treatment of roginolisib with nivolumab and cisplatin. PI3K-δ was detected in 66/89 (74%) MPM tumors and was associated with reduced overall survival (12 vs. 25 months, P=0.0452). Roginolisib induced apoptosis in MPM cells and enhanced the anti-tumor efficacy of AKT and mTOR kinase inhibitors by suppressing PI3K-δ/AKT/mTOR and ERK1/2 signaling. Furthermore, the combination of roginolisib with chemotherapy and immunotherapy re-balanced the immune cell composition, increasing effector T-cells and reducing immune suppressive cells. Overall, roginolisib induces apoptosis in MPM cells and increases the antitumor immune cell effector function when combined with nivolumab and cisplatin. These results provide first insights on the potential of roginolisib as a therapeutic agent in patients with MPM and its potential in combination with established immunotherapy regimen.

Pegargiminase Plus First-Line Chemotherapy in Patients With Nonepithelioid Pleural Mesothelioma: The ATOMIC-Meso Randomized Clinical Trial

Importance

Arginine deprivation using ADI-PEG20 (pegargiminase) combined with chemotherapy is untested in a randomized study among patients with cancer. ATOMIC-Meso (ADI-PEG20 Targeting of Malignancies Induces Cytotoxicity-Mesothelioma) is a pivotal trial comparing standard first-line chemotherapy plus pegargiminase or placebo in patients with nonepithelioid pleural mesothelioma.

Objective

To determine the effect of pegargiminase-based chemotherapy on survival in nonepithelioid pleural mesothelioma, an arginine-auxotrophic tumor.

Design, Setting, and Participants

This was a phase 2-3, double-blind randomized clinical trial conducted at 43 centers in 5 countries that included patients with chemotherapy-naive nonepithelioid pleural mesothelioma from August 1, 2017, to August 15, 2021, with at least 12 months' follow-up. Final follow-up was on August 15, 2022. Data analysis was performed from March 2018 to June 2023.

Intervention

Patients were randomly assigned (1:1) to receive weekly intramuscular pegargiminase (36.8 mg/m2) or placebo. All patients received intravenous pemetrexed (500 mg/m2) and platinum (75-mg/m2 cisplatin or carboplatin area under the curve 5) chemotherapy every 3 weeks up to 6 cycles. Pegargiminase or placebo was continued until progression, toxicity, or 24 months.

Main Outcomes and Measures

The primary end point was overall survival, and secondary end points were progression-free survival and safety. Response rate by blinded independent central review was assessed in the phase 2 portion only.

Results

Among 249 randomized patients (mean [SD] age, 69.5 [7.9] years; 43 female individuals [17.3%] and 206 male individuals [82.7%]), all were included in the analysis. The median overall survival was 9.3 months (95% CI, 7.9-11.8 months) with pegargiminase-chemotherapy as compared with 7.7 months (95% CI, 6.1-9.5 months) with placebo-chemotherapy (hazard ratio [HR] for death, 0.71; 95% CI, 0.55-0.93; P = .02). The median progression-free survival was 6.2 months (95% CI, 5.8-7.4 months) with pegargiminase-chemotherapy as compared with 5.6 months (95% CI, 4.1-5.9 months) with placebo-chemotherapy (HR, 0.65; 95% CI, 0.46-0.90; P = .02). Grade 3 to 4 adverse events with pegargiminase occurred in 36 patients (28.8%) and with placebo in 21 patients (16.9%); drug hypersensitivity and skin reactions occurred in the experimental arm in 3 patients (2.4%) and 2 patients (1.6%), respectively, and none in the placebo arm. Rates of poststudy treatments were comparable in both arms (57 patients [45.6%] with pegargiminase vs 58 patients [46.8%] with placebo).

Conclusions and Relevance

In this randomized clinical trial of arginine depletion with pegargiminase plus chemotherapy, survival was extended beyond standard chemotherapy with a favorable safety profile in patients with nonepithelioid pleural mesothelioma. Pegargiminase-based chemotherapy as a novel antimetabolite strategy for mesothelioma validates wider clinical testing in oncology.

Trial Registration

ClinicalTrials.gov Identifier: NCT02709512.

The lncRNAs Gas5, MALAT1 and SNHG8 as diagnostic biomarkers for epithelial malignant pleural mesothelioma in Egyptian patients

Long noncoding RNAs have been shown to be involved in a myriad of physiological and pathological pathways. To date, malignant pleural mesothelioma (MPM) is considered an extremely aggressive cancer. One reason for this is the late diagnosis of the disease, which can occur within 30-40 years of asbestos exposure. There is an immense need for the development of new, sensitive, inexpensive and easy methods for the early detection of this disease other than invasive methods such as biopsy. The aim of this study was to determine the expression of circulating lncRNAs in mesothelioma patient plasma to identify potential biomarkers. Ten previously identified lncRNAs that were shown to be aberrantly expressed in mesothelioma tissues were selected as candidates for subsequent validation. The expression of the ten selected candidate lncRNAs was verified via quantitative PCR (qPCR) in human plasma samples from mesothelioma patients versus healthy controls. The expression levels of circulating GAS5, SNHG8 and MALAT1 were significantly greater in plasma samples from patients than in those from controls. The ROC analysis of both MALAT1 and SNHG8 revealed 88.89% sensitivity and 66.67% specificity. The sensitivity of these markers was greater than that of GAS5 (sensitivity 72.22% and specificity 66.67%). The regression model for GAS5 was statistically significant, while that for SNHG8 and MALAT1 was not significant due to the small sample size. The area under the curve (AUC) of the three ROC curves was acceptable and significant: 0.7519 for GAS5, 0.7352 for SNHG8 and 0.7185 for MALAT1. This finding confirmed their ability to be used as markers. The three lncRNAs were not affected by age, sex or smoking status. The three lncRNAs showed great potential as independent predictive diagnostic biomarkers. Although the prediction model for MALAT1 did not significantly differ, MALAT1 was significantly expressed in patients more than in controls (p = 0.0266), and the recorded sensitivity and specificity were greater than those of GAS5.

MesoGraph: Automatic profiling of mesothelioma subtypes from histological images

Mesothelioma is classified into three histological subtypes, epithelioid, sarcomatoid, and biphasic, according to the relative proportions of epithelioid and sarcomatoid tumor cells present. Current guidelines recommend that the sarcomatoid component of each mesothelioma is quantified, as a higher percentage of sarcomatoid pattern in biphasic mesothelioma shows poorer prognosis. In this work, we develop a dual-task graph neural network (GNN) architecture with ranking loss to learn a model capable of scoring regions of tissue down to cellular resolution. This allows quantitative profiling of a tumor sample according to the aggregate sarcomatoid association score. Tissue is represented by a cell graph with both cell-level morphological and regional features. We use an external multicentric test set from Mesobank, on which we demonstrate the predictive performance of our model. We additionally validate our model predictions through an analysis of the typical morphological features of cells according to their predicted score.

Highlighting the immunohistochemical differences of malignant mesothelioma subtypes via case presentations

Malignant mesothelioma (MM) is a rare tumor of mesothelial cells, with an increasing incidence both in developed and developing countries. MM has three major histological subtypes, in order of frequency, according to the World Health Organization (WHO) Classification of 2021: epithelioid, biphasic, and sarcomatoid MM. Distinction may be a challenging task for the pathologist, due to the unspecific morphology. Here, we present two cases of diffuse MM subtypes to emphasize the immunohistochemical (IHC) differences, and to facilitate diagnostic difficulties. In our first case of epithelioid mesothelioma, the neoplastic cells showed cytokeratin 5/6 (CK5/6), calretinin, and Wilms-tumor-1 (WT1) expression, while remaining negative with thyroid transcription factor-1 (TTF-1). BRCA1 associated protein-1 (BAP1) negativity was seen in the neoplastic cells' nucleus, reflecting loss of the tumor suppressor gene. In the second case of biphasic mesothelioma, expression of epithelial membrane antigen (EMA), CKAE1/AE3, and mesothelin was observed, while WT1, BerEP4, CD141, TTF1, p63, CD31, calretinin, and BAP1 expressions were not detected. Due to the absence of specific histological features, the differentiation between MM subtypes could be a challenging task. In routine diagnostic work, IHC may be the proper method in distinction. According to our results and literature data, CK5/6, mesothelin, calretinin, and Ki-67 should be applied in subclassification.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of lung cancer and mesothelioma

Immunotherapy has transformed lung cancer care in recent years. In addition to providing durable responses and prolonged survival outcomes for a subset of patients with heavily pretreated non-small cell lung cancer (NSCLC), immune checkpoint inhibitors (ICIs)— either as monotherapy or in combination with other ICIs or chemotherapy—have demonstrated benefits in first-line therapy for advanced disease, the neoadjuvant and adjuvant settings, as well as in additional thoracic malignancies such as small-cell lung cancer (SCLC) and mesothelioma. Challenging questions remain, however, on topics including therapy selection, appropriate biomarker-based identification of patients who may derive benefit, the use of immunotherapy in special populations such as people with autoimmune disorders, and toxicity management. Patient and caregiver education and support for quality of life (QOL) is also important to attain maximal benefit with immunotherapy. To provide guidance to the oncology community on these and other important concerns, the Society for Immunotherapy of Cancer (SITC) convened a multidisciplinary panel of experts to develop a clinical practice guideline (CPG). This CPG represents an update to SITC’s 2018 publication on immunotherapy for the treatment of NSCLC, and is expanded to include recommendations on SCLC and mesothelioma. The Expert Panel drew on the published literature as well as their clinical experience to develop recommendations for healthcare professionals on these important aspects of immunotherapeutic treatment for lung cancer and mesothelioma, including diagnostic testing, treatment planning, immune-related adverse events, and patient QOL considerations. The evidence- and consensus-based recommendations in this CPG are intended to give guidance to cancer care providers using immunotherapy to treat patients with lung cancer or mesothelioma.

Pleural mesothelioma classification-update and challenges

Mesothelial tumors are classified into benign or preinvasive tumors, and mesotheliomas. The benign or preinvasive group includes adenomatoid tumors, well-differentiated papillary mesothelial tumors, and mesothelioma in situ. Malignant tumors are mesotheliomas and can be localized or diffuse. Histological classification of invasive mesotheliomas into three major subtypes-epithelioid, sarcomatoid, and biphasic is prognostically important. It also plays a significant role in the treatment decisions of patients diagnosed with this deadly disease. Grading and subtyping of epithelioid mesotheliomas have been one of the major changes in the recent WHO classification of pleural tumors. Mesothelioma in situ has emerged as a precisely defined clinico-pathologic entity that for diagnosis requires demonstration of loss of BAP1 or MTAP by immunohistochemistry, or CDKN2A homozygous deletion by FISH. The use of these two biomarkers improves the diagnostic sensitivity of effusion specimens  and limited tissue samples and is valuable in establishing the diagnosis of epithelioid mesothelioma. In this review, recent changes in the histologic classification of pleural mesothelioma, importance of ancillary diagnostic studies, and molecular characteristics of mesotheliomas are discussed.

Malignant peritoneal mesothelioma: correlation between CT imaging features and histologic subtypes

PURPOSE

To identify correlation between CT imaging features and histologic subtypes of Malignant Peritoneal Mesothelioma (MPM).

METHODS

This was a retrospective single-center study of 51 consecutive patients with the diagnosis of Malignant Peritoneal Mesothelioma (MPM). The tumors were classified into pure epithelioid type and those with sarcomatoid component (pure sarcomatoid and biphasic type). Imaging features of these subtypes were compared for extent and type of peritoneal thickening, omental thickening, abdominal visceral infiltration, abdominal wall infiltration, and loco-regional and distant metastases. Fisher's Exact test was used to correlate the association of imaging features with histology types followed by multivariate analysis using logistic regression test.

RESULTS

32 males and 19 females with a median age of 63 years (range 35-86 years) were included in the study. 41/51 (80%) were epithelioid histology type and 10/51 (20%) had sarcomatoid component (3 pure sarcomatoid type, 7 biphasic type). Abdominal visceral infiltration was seen more commonly in cases of MPM with sarcomatoid component (p = 0.001). Sarcomatoid type also had a frequent association with metastases (p = 0.001) and discrete masses (p = 0.01). Epithelioid type was commonly associated with ascites (p = 0.04). On multivariate analysis, most significant correlation was identified between the sarcomatoid type and imaging features of metastases (p = 0.001) and visceral infiltration (p = 0.019).

CONCLUSION

Sarcomatoid type of MPM showed significant correlation with more aggressive imaging features of metastases and visceral infiltration as compared to epithelioid type.

Use of preclinical models for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive cancer most commonly caused by prior exposure to asbestos. Median survival is 12-18 months, since surgery is ineffective and chemotherapy offers minimal benefit. Preclinical models that faithfully recapitulate the genomic and histopathological features of cancer are critical for the development of new treatments. The most commonly used models of MPM are two-dimensional cell lines established from primary tumours or pleural fluid. While these have provided some important insights into MPM biology, these cell models have significant limitations. In order to address some of these limitations, spheroids and microfluidic chips have more recently been used to investigate the role of the three-dimensional environment in MPM. Efforts have also been made to develop animal models of MPM, including asbestos-induced murine tumour models, MPM-prone genetically modified mice and patient-derived xenografts. Here, we discuss the available in vitro and in vivo models of MPM and highlight their strengths and limitations. We discuss how newer technologies, such as the tumour-derived organoids, might allow us to address the limitations of existing models and aid in the identification of effective treatments for this challenging-to-treat disease.

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.

Clinical prognostic factors in pleural mesothelioma: best supportive care and anti-tumor treatments in a real-life setting

BACKGROUND

This study aims to investigate patient- and disease characteristics associated with survival in malignant pleural mesothelioma (MPM) patients with anti-tumor treatment or with best supportive care (BSC).

MATERIALS AND METHODS

Consecutive MPM cases diagnosed in North Denmark Region from 1972 to 2015 were reevaluated and verified by two pathologists using modern immunohistochemical techniques. Danish registries and hospital records were used to gather patient-, asbestos exposure-, and disease information.

RESULTS

Of the 279 patients, anti-tumor treatment was administered to 184 patients (66.0%). All of those received chemotherapy alone or as part of a multimodal treatment, where pemetrexed was given to 126 (68.5%) patients. Asbestos exposure was documented in 92.5% of all patients. In the treated group, mean age was lower (66 years versus 74 years, p < 0.01), rate of occupational asbestos exposure was higher (74.5 versus 54.7%, p < 0.01), more patients had better performance score (98.4 versus 60%, p < 0.01) and stage was lower (81 versus 63.2%, p < 0.01) compared to the BSC group. Multivariate analysis showed that epithelioid subtype was the only common prognostic factor for OS in both groups. In BSC patients, good PS and female gender was associated with improved OS. Median overall survival (OS) was 17 versus 4 months (p < 0.01), and independently of the histopathological subtype, the median and 2-year survival was higher in the treated versus the BSC group (p < 0.02).

CONCLUSIONS

This retrospective study showed that epithelioid subtype is the only independent positive prognostic factor of survival in treated patients with MPM. For BSC patients, the epithelioid subtype, good PS, and female gender were positive prognostic factors, while age and comorbidities were not significant. This study with long-term follow-up of treated and BSC MPM patients can contribute to the clinical stratification of patients. Further validation is appropriate to verify these findings.

Pleural mesothelioma classification update

The 2015 WHO classification of pleural mesotheliomas includes three major histologic subtypes-epithelioid, sarcomatoid, and biphasic. Recent genomic data has supported the need for a more granular and clinically valid classification beyond the three current subtypes. Because of tumor rarity and overlapping histologic features with other tumor types, diagnostic immunohistochemical work up is essential component in establishing the final diagnosis of mesothelioma. The use of BAP1 and CDKN2A/MTAP improves the diagnostic sensitivity of effusion specimens and are valuable in establishing the diagnosis of epithelioid mesothelioma. The major change in the forthcoming WHO classification is the inclusion of mesothelioma in situ as a diagnostic category. In this review, we discuss recently proposed changes in the histologic classification of pleural mesothelioma, differential diagnosis, and importance of ancillary diagnostic studies.

Update on biology and management of mesothelioma

Malignant pleural mesothelioma is an aggressive, incurable cancer that is usually caused by asbestos exposure several decades before symptoms arise. Despite widespread prohibition of asbestos production and supply, its incidence continues to increase. It is heterogeneous in its presentation and behaviour, and diagnosis can be notoriously difficult. Identification of actionable gene mutations has proven challenging and current treatment options are largely ineffective, with a median survival of 10-12 months.However, the past few years have witnessed major advances in our understanding of the biology and pathogenesis of mesothelioma. This has also revealed the limitations of existing diagnostic algorithms and identified new treatment targets.Recent clinical trials have re-examined the role of surgery, provided new options for the management of associated pleural effusions and heralded the addition of targeted therapies. The increasing complexity of mesothelioma management, along with a desperate need for further research, means that a multidisciplinary team framework is essential for the delivery of contemporary mesothelioma care.This review provides a synthesised overview of the current state of knowledge and an update on the latest research in the field.

Trabectedin in Malignant Pleural Mesothelioma: Results From the Multicentre, Single Arm, Phase II ATREUS Study

INTRODUCTION

New therapeutic approaches in unresectable malignant pleural mesothelioma (MPM) are eagerly awaited. Trabectedin is an antitumor agent with an effect on cancer cell proliferation and a modulating action on tumor microenvironment. The ATREUS study explored the activity and safety of trabectedin in patients with unresectable MPM.

METHODS

Epithelioid patients with MPM received trabectedin as second-line while biphasic/sarcomatoid patients with MPM as first- or second-line therapy. Treatment was given intravenously at an initially planned dose of 1.3 mg/m² every 3 weeks, until progression or unacceptable toxicity. The primary endpoint was progression-free survival rate at 12 weeks (PFS_12wks).

RESULTS

Overall, 78 patients (54%) had epithelioid and 67 (46%) nonepithelioid MPM. PFS_12wks in 62 evaluable patients with epithelioid MPM was 43.5% (80% confidence interval 34.9%-52.5%); median progression-free and overall survival were 2.4 and 9.0 months, respectively. PFS_12wks in 52 evaluable patients with nonepithelioid MPM was 30.8% (90% confidence interval 20.3%-42.9%); median progression-free and overall survival were 1.7 and 5.4 months. Trabectedin starting dose was amended due to excess of liver toxicity. Eighty-four (64%) and 48 (36%) patients received 1.3 mg/m² and 1.1. mg/m², respectively. The most common grade 3-4 toxicities were hepatotoxicity, leukopenia/neutropenia, and fatigue. Grade 3-4 hepatotoxicity was reported in 59 (70%) patients treated at 1.3 mg/m², and in 19 (40%) treated at 1.1 mg/m².

CONCLUSIONS

Trabectedin showed modest clinical activity, at the expense of relevant liver toxicity. Further development of this drug in MPM at full doses is not warranted.

Gender-based Disparities in Receipt of Care and Survival in Malignant Pleural Mesothelioma

BACKGROUND

Despite accounting for a minority of malignant pleural mesothelioma (MPM) diagnoses, females may experience differential survival relative to males. It is unclear if there are gender-based differences in receipt of treatment or disease-related outcomes for patients with MPM. We therefore utilized the National Cancer Database (NCDB) to assess patterns-of-care and overall survival (OS) among patients with MPM by gender.

MATERIALS AND METHODS

Patients with histologically confirmed MPM treated from 2004 to 2013 were identified from the NCDB. The association between female gender and OS was assessed using multivariable Cox proportional hazards models with propensity score matching. Patterns-of-care were assessed using multivariable logistic regression. The overall treatment effect was tested in subsets of patients by treatment strategy, histology, and clinical stage.

RESULTS

A total of 18,799 patients were identified, of whom 14,728 (78%) were male and 4071 (22%) were female. Females were statistically more likely to present at a younger age, with fewer comorbidities, and with epithelioid histology. Despite these favorable prognostic features, women were less likely to receive surgery (P ≤ .001) or chemotherapy (P ≤ .001) compared with males. On multivariable analysis, female gender was associated with improved OS (hazard ratio, 0.83; 95% confidence interval, 0.80-0.86; P ≤ .001). Gender-based survival differences were seen across all stages, but only among patients with epithelioid (P ≤ .001) and not biphasic (P = .17) or sarcomatoid (P = 1.00) histology.

CONCLUSIONS

Surgery and chemotherapy are disproportionately underutilized in female patients with MPM. Despite this concerning disparity, female gender is independently associated with improved survival relative to males. Further research to understand factors that lead to gender disparities in MPM is warranted.

Remarkable response to nivolumab in sarcomatoid malignant pleural mesothelioma with high PD-L1

We report herein a case of sarcomatoid malignant pleural mesothelioma (MPM) with high PD-L1 expression who was refractory to standard chemotherapy but had a remarkable and sustained response to nivolumab. A 78-year-old man presented with right chest pain. Computed tomography (CT) showed a solid mass extending to the right pleura. Histopathological examination revealed the proliferation of spindle to pleomorphic ovoid shaped tumour cells, which are positive for calretinin and podoplanin. The patient was diagnosed with sarcomatoid MPM. Despite treatment with carboplatin and pemetrexed, the primary lesion rapidly progressed and new multiple pleural metastases were observed. Although his performance status decreased with advancing of symptoms and adverse events, nivolumab was administered. After the nivolumab treatment, CT showed a significant reduction in pleural tumours with a marked improvement in symptoms. In the primary specimens, TPS of PD-L1 was 80%. The patient has continued this treatment with sustained and remarkable effectiveness with good quality of life (QOL).

Interobserver variation in the assessment of the sarcomatoid and transitional components in biphasic mesotheliomas

The percentage of sarcomatoid component has an impact on prognosis in patients with biphasic malignant pleural mesothelioma. Recent study showed that the transitional pattern similar to sarcomatoid component of malignant mesothelioma has negative prognostic significance. Practice guidelines recommend quantification of sarcomatoid component despite poor diagnostic reproducibility of biphasic mesothelioma among thoracic pathologists. The aim of this study was to determine the interobserver agreement in the quantification of sarcomatoid component, and in the diagnosis of a transitional component in the biphasic malignant mesothelioma. Thirteen experts in thoracic pathology reviewed the representative H&E and cytokeratin whole-slide images of the 54 biphasic mesotheliomas, without knowledge of BAP1 or p16 deletion status, and completed the survey of 25 questions. The overall interobserver agreement in the assessment of the percentage of the sarcomatoid component in 25% increments was good (wK = 0.62). Excellent agreement was present in 14 of 54 cases (26%), and 3 cases were unanimously scored. Excellent agreement was reached for the cases with 0-24% and > 75% of the sarcomatoid component.The most commonly used criteria for the diagnosis of sarcomatoid component were malignant spindle cells, frank sarcomatoid features and high N/C ratio. The overall interobserver agreement for transitional pattern was fair (wK = 0.40). Unanimous opinion about the absence of transitional pattern was observed in only one case. At least 70% agreement regarding the presence of transitional pattern was observed in 12 cases, with the rest of the cases showing a wide range of disagreement. Morphologic characteristics that favor transitional pattern over non-transitional include sheet-like growth of cohesive, plump, elongated epithelioid cells with well-defined cell borders and a tendency to transition into spindle cells. Our study defined precise morphologic criteria that may be used in the differential diagnosis between transitional pattern and other mesothelioma subtypes including sarcomatoid and epithelioid.

Building a Bridge between Chemotherapy and Immunotherapy in Malignant Pleural Mesothelioma: Investigating the Effect of Chemotherapy on Immune Checkpoint Expression

In light of the promising results of immune checkpoint blockade (ICPB) in malignant pleural mesothelioma (MPM), we investigated the effect of different chemotherapeutic agents on the expression of immune checkpoints (ICPs) in order to rationally design a good treatment schedule for their combination with ICP blocking antibodies. Cisplatin, oxaliplatin and pemetrexed are interesting chemotherapeutic agents to combine with immunotherapy given their immunomodulatory capacities. We looked into cisplatin and pemetrexed because their combination is used as first-line treatment of MPM. Additionally, the effect of the immunogenic chemotherapeutic agent, oxaliplatin, was also studied. Three different MPM cell lines were used for representation of both epithelioid and sarcomatoid subtypes. The desired inhibitory concentrations of the chemotherapeutic agents were determined with the SRB-assay. Allogeneic co-cultures of MPM cells with healthy donor peripheral blood mononuclear cells (PBMC) were set up to assess the effect of these chemotherapeutic agents on the expression of ICPs (PD-1, LAG-3, TIM-3) and their ligands (PD-L1, PD-L2, galectin-9). Cisplatin might be a promising treatment to combine with ICP blocking antibodies since our MPM cell lines were most susceptible to this stand-alone treatment. We found that the expression of ICPs and their ligands on both MPM cells and PBMC was mostly downregulated or unaltered when treated with chemotherapeutic agents, though no clear trend could be determined.

Pathologic Considerations and Standardization in Mesothelioma Clinical Trials

The accurate diagnosis of mesothelioma is critical for the appropriate clinical management of this cancer. Many issues complicate making the diagnosis of mesothelioma including the presence of reactive mesothelial cells in benign pleural effusions, the heterogeneity of mesothelioma histopathology, the relatively high incidence of other epithelial malignancies that metastasize to the pleura, and primary sarcomas that arise within the pleura. Given the rapidly evolving field of molecular profiling and the need for translational correlates in mesothelioma clinical trials, the National Cancer Institute (NCI)-International Association for the Study of Lung Cancer-Mesothelioma Applied Research Foundation Clinical Trials Planning Meeting was convened in March 2017 to develop a consensus on standard pathology guidelines for future NCI-sponsored clinical trials in mesothelioma. This consensus statement covers recommendations for specimen handling, pathologic classification and diagnosis, biobanking, and tissue correlative studies.

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.

Systemic Therapy Use and Outcomes After Relapse from Preoperative Radiation and Extrapleural Pneumonectomy for Malignant Pleural Mesothelioma

BACKGROUND

Multimodality therapy with preoperative radiation (RT) followed by extrapleural pneumonectomy (EP) for patients with operable malignant pleural mesothelioma (MPM) has demonstrated encouraging results. At relapse, there are few data on the tolerance and efficacy of systemic therapies after prior multimodality therapy.

MATERIALS AND METHODS

We conducted a retrospective analysis of patients with relapsed MPM after RT and EPP ± adjuvant chemotherapy to determine overall survival (OS; date of relapse to death) and the proportion of patients that received systemic therapy and associated response rate (RR). OS was estimated using Kaplan-Meier method and potential prognostic variables were examined.

RESULTS

Fifty-three patients were included (2008-2016). Median OS was 4.8 months (median follow-up 4.4 months, range 0.03-34.8). Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≥2, disease-free interval (DFI) <1 year, and hemoglobin ≤110 g/L at recurrence were associated with worse prognosis. Thirty-six percent of patients received any systemic therapy, whereas it was omitted in 62% because of poor PS. RR was 15% (0 complete responses, 15% partial responses) in 13 individuals with response-evaluable disease. Therapy was discontinued because of toxicity (6/15) or disease progression (5/15), and median number of cycles was four.

CONCLUSION

Patients with relapsed MPM following RT and EPP, especially those with ECOG PS ≥2, DFI <1 year, and hemoglobin ≤110 g/L at recurrence, have poor prognosis and low RR to first-line systemic therapy. Earlier detection and novel diagnostic markers of relapse as well as potential neoadjuvant or adjuvant systemic therapy should be investigated in future studies.

IMPLICATIONS FOR PRACTICE

The results of this study have reinforced the importance of careful selection of appropriate candidates for this combined-modality approach and favor prompt detection of recurrence with early and regular postoperative imaging and biopsy of suspected relapsed disease along with rapid initiation of systemic therapy even in patients with very low burden of disease. Furthermore, with the emergence of new systemic agents targeting different histological subtypes of malignant pleural mesothelioma, histological sampling of recurrence could inform therapeutic decisions in the future.

Effects of Reduction in Tumor Burden on Survival in Epithelioid Malignant Pleural Mesothelioma

OBJECTIVE

To understand the relationship between response and survival in malignant pleural mesothelioma (MPM).

PATIENTS AND METHODS

The original clinical trial was conducted from April 1999 through March 2001. Patients with epithelioid MPM (n=305) were categorized using modified pleural Response Evaluation Criteria in Solid Tumors by whether they responded to treatment. Median progression-free survival (PFS) and overall survival (OS) were estimated and hazard ratios for responders and nonresponders were estimated and compared using the log-rank test. Multivariable Cox proportional hazards models were used to adjust for baseline prognostic factors.

RESULTS

Patients who responded to frontline therapy had a significantly longer OS (hazard ratio, 0.34; 95% CI, 0.24-0.49; median, 20.6 months; 95% CI, 15.3 months to not reached) than did those who did not respond (median, 9.4 months; 95% CI, 8.1-11.0 months) (P<.001). Similarly, responders had a significantly longer PFS (hazard ratio, 0.50; 95% CI, 0.39-0.64; median, 7.8 months; 95% CI, 6.5-8.5 months) than did nonresponders (median, 3.7 months; 95% CI, 2.9-4.3 months) (P<.001). These results were confirmed when adjusting for baseline prognostic factors. We also observed a survival benefit associated with disease stabilization in MPM.

CONCLUSION

Our findings indicate that reduction in tumor burden or disease stabilization determined using modified pleural Response Evaluation Criteria in Solid Tumors is strongly associated with OS and PFS in epithelioid MPM.

Synergistic targeting of malignant pleural mesothelioma cells by MDM2 inhibitors and TRAIL agonists

Malignant Pleural Mesothelioma (MPM) is a chemoresistant tumor characterized by low rate of p53 mutation and upregulation of Murine Double Minute 2 (MDM2), suggesting that it may be effectively targeted using MDM2 inhibitors. In the present study, we investigated the anticancer activity of the MDM2 inhibitors Nutlin 3a (in vitro) and RG7112 (in vivo), as single agents or in combination with rhTRAIL.

In vitro studies were performed using MPM cell lines derived from epithelioid (ZL55, M14K), biphasic (MSTO211H) and sarcomatoid (ZL34) MPMs. In vivo studies were conducted on a sarcomatoid MPM mouse model.

In all the cell lines tested (with the exception of ZL55, which carries a biallelic loss-of-function mutation of p53), Nutlin 3a enhanced p21, MDM2 and DR5 expression, and decreased survivin expression. These changes were associated to cell cycle arrest but not to a significant induction of apoptosis. A synergistic pro-apoptotic effect was obtained through the association of rhTRAIL in all the cell lines harboring functional p53. This synergistic interaction of MDM2 inhibitor and TRAIL agonist was confirmed using a mouse preclinical model. Our results suggest that the combined targeting of MDM2 and TRAIL might provide a novel therapeutic option for treatment of MPM patients, particularly in the case of sarcomatoid MPM with MDM2 overexpression and functional inactivation of wild-type p53.

Treatment of Malignant Pleural Mesothelioma: American Society of Clinical Oncology Clinical Practice Guideline

Purpose To provide evidence-based recommendations to practicing physicians and others on the management of malignant pleural mesothelioma. Methods ASCO convened an Expert Panel of medical oncology, thoracic surgery, radiation oncology, pulmonary, pathology, imaging, and advocacy experts to conduct a literature search, which included systematic reviews, meta-analyses, randomized controlled trials, and prospective and retrospective comparative observational studies published from 1990 through 2017. Outcomes of interest included survival, disease-free or recurrence-free survival, and quality of life. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations. Results The literature search identified 222 relevant studies to inform the evidence base for this guideline. Recommendations Evidence-based recommendations were developed for diagnosis, staging, chemotherapy, surgical cytoreduction, radiation therapy, and multimodality therapy in patients with malignant pleural mesothelioma. Additional information is available at www.asco.org/thoracic-cancer-guidelines and www.asco.org/guidelineswiki .

Isolated thoracic perfusion with chemofiltration for progressive malignant pleural mesothelioma

Introduction

Therapy of malignant pleural mesothelioma and especially the adequate role of surgery in this context remain the subject of controversial discussions. Radical surgery in particular, which is associated with substantial morbidity, failed to translate into a definite survival advantage. We report on interim results of an ongoing Phase II study of regional chemotherapy in terms of isolated thoracic perfusion with chemofiltration (ITP-F).

Patients and methods

Twenty-eight patients (25 male, 3 female, mean age 63.4 years) with advanced pleural mesothelioma were included in this study. Isolation of the chest was achieved by insertion of a venous and arterial stop-flow balloon catheter via a femoral access. The aorta and inferior vena cava were blocked at the level of the diaphragm and the upper arms were blocked by pneumatic cuffs. Chemotherapy, consisting of 60 mg/m² cisplatin and 15 mg/m² mitoxantrone, was administered directly into the aorta. The isolated circuit was maintained for 15 minutes followed bŷ45 minutes of chemofiltration with a hemoprocessor until 5 L of filtrate were reached. The endpoints of the study were overall survival and quality of life (QoL).

Results

Out of 28 patients enrolled in the study, 5 had prior surgeries, 10 patients had systemic chemotherapy, and 5 patients additional irradiation. In all patients in restaging, clinical progress was noted. In all, 162 cycles were administered. Due to chemofiltration, toxicity was within tolerable limits, revealing World Health Organization grade I leucopenia and thrombocytopenia in 9 patients and mucositis grade I in 6 patients. The major surgical complication was inguinal lymphatic fistula in 40% of the cases. Gastrointestinal toxicity and/or neurotoxicity were never observed. One-year survival was 49%, 2-year and 3-year survival was 31%, and 5-year survival was 18%. Median overall survival was 12 months and progression-free survival 9 months.

Conclusion

ITP-F for patients with advanced pleural mesothelioma, progressive after standard therapies, is an effective and well-tolerated treatment modality, offering comparably long survival data at a good QoL.

Temporal and spatial heterogeneity of programmed cell death 1-Ligand 1 expression in malignant mesothelioma

Background: Programmed Cell Death 1-Ligand 1 (PD-L1) and Programmed Death Protein 1 (PD-1) blocking antibodies are promising immunotherapies for malignancies. We have previously shown PD-L1 expression in 40% of malignant mesothelioma (MM); however, the temporal and spatial heterogeneity of its expression has not been thoroughly studied. We compared PD-L1 expression between paired primary and metastatic MM. Design: Pathology files (1995-2016) were searched for MM with tissue from multiple sites and/or time points. PD-L1 (clone SP263) expression was reviewed by 2 authors. Mesothelioma cell lines (H2461, One 58, EM-MESO) were cultured with or without vinorelbine or pemetrexed. Following incubation, PD-L1 expression (clone MIH1) was analyzed by flow cytometry. Results: 64 patients (53 men, median age, 64 years) with epithelioid (N = 50), biphasic (N = 11) or sarcomatoid (N = 2) MM or well differentiated papillary mesothelioma (N = 1) (pleural, n = 56; peritoneal, n = 8) were included. Patients had a subsequent specimen from the primary site (n = 48), from a metastasis (n = 6), or both (n = 10). Reviewers agreed on PD-L1 expression in 133 of 151 (88%) specimens. There was agreement of PD-L1 expression between paired primary lesions obtained at separate time points in 47 of 58 (81%) and between paired primary and metastatic lesions in 11 of 16 (69%) cases. A significant increase in PD-L1 expression was observed in all 3 MM cell lines (p < 0.003 each) following exposure to vinorelbine but not to pemetrexed. Conclusion: Overall there is good agreement in PD-L1 expression between paired MM lesions; however, the 19-31% of cases with discordant PD-L1 expression, and the dynamics of PD-L1 expression may limit its use as a predictive biomarker for therapy.

c-Met expression and MET amplification in malignant pleural mesothelioma

c-Met is a receptor tyrosine kinase shown to be overexpressed in malignant pleural mesothelioma (MPM). Whereas MET mutations have been identified in 3%-16% of MPMs, MET amplification has recently been reported in a single epithelioid MPM. We studied c-Met expression and MET amplification in a large MPM cohort and correlated results with morphologic and clinical features. We report the first case of MET amplification in sarcomatoid MPM. MPMs from surgical pathology files (1989-2014) were reviewed. c-Met immunohistochemistry was performed. Staining intensity and distribution were multiplied (H-score). Staining localization (cytoplasmic and/or membranous) was noted. Fluorescence in situ hybridization was performed using probes for MET and centromere 7. One hundred forty-nine patients (median age, 68.0years; interquartile range, 61-75) had epithelioid (n=97), biphasic (n=18), or sarcomatoid (n=34) MPM. Median follow-up was 10.1months (range, 0.1-222.5). One hundred thirty patients died of disease; 2 were alive with disease. c-Met was expressed in 147 MPMs. c-Met staining intensity, distribution, and H-score differed among the histologic subtypes (P=.015; P=.0001, and P=.0005, respectively), but none were predictive of survival. Epithelioid subtype had greater c-Met expression. MET amplification was identified in 1 sarcomatoid MPM and MET duplication in 1 epithelioid MPM; both had poor outcomes. Chromosome 7 aneusomy was observed in 54 of 144 (37.5%) MPMs and associated with decreased overall survival in sarcomatoid MPMs (hazard ratio=2.81; 95% confidence interval, 1.21-6.51; P=.01). In conclusion, c-Met is expressed in MPM, with significant differences in expression among histologic subtypes. MET amplification is a rare event in MPM, making it an unlikely common pathogenesis for c-Met expression.

Brain metastases in malignant pleural mesothelioma

The brain is a rare site of metastasis in malignant pleural mesothelioma (MPM), and its clinical features and prognosis remain unclear. The aim of this study was to investigate the incidence, prognosis, and risk factors for brain metastases (BM) in MPM patients. Between July 1993 and October 2014, 150 patients with histologically proven MPM were included in this retrospective study. The cumulative incidence of BM was estimated with the Kaplan-Meier method, and differences between groups were analyzed by the log-rank test. Multivariate logistic regression analysis was applied to assess risk factors for BM. The median follow-up time was 11 months (range 0-154.0 months). A total of eight patients (5.3 %) developed BM during the course of their illness. Multivariate analysis identified age <65 years (odds ratio [OR] = 5.83, p = 0.038) and International Mesothelioma Interest Group stage IV (OR = 1.69, p = 0.040) as independent factors related to increased risk of developing BM. The 1-and 2-year cumulative rates of BM were 4.0 % (95 % confidence intervals [CI] 1.4-8.5 %) and 5.3 % (95 % CI 2.3-10.2 %), respectively. Our study showed that the overall survival (OS) of patients with BM was worse than that of patients without BM (median OS 6.5 vs. 11.0 months, p = 0.037). The prognosis for BM in MPM patients is poor. Clinicians should perform careful screening for BM, especially in patients with risk factors.

Sarcomatoid mesothelioma: future advances in diagnosis, biomolecular assessment, and therapeutic options in a poor-outcome disease

Malignant pleural mesothelioma (MPM) is the most frequent pleural neoplasm, with asbestos exposure as one of the recognized carcinogen agents, causative in 80% of cases. The prognosis is poor; median survival of untreated cases is 6-9 months, with fewer than 5% of patients surviving 5 years. Sarcomatoid mesothelioma (SM) represents the subtype with the worst outcome and median survival ranging from 3.5 to 8 months. In the last few years, an accurate differentiation between the subtypes of MPM has become a crucial issue, due to differences in chemosensitivity and clinical outcome, and several studies have evaluated different immunohistochemical markers to better define the diagnosis. The different and worse outcome of patients with SM and, in general, nonepithelioid subtypes makes it intriguing to select these cases to better study the biomolecular profile in order to find factors linked to prognosis and/or predictive of therapeutic response. Considering recent studies on miRNA and genetic mapping, further investigation of this rare subtype might represent a field for basic and clinical-translational research providing for more tailored therapies.