Epithelioid Malignant Pleural Mesothelioma Research Articles

Utility of homozygous p16/CDKN2A deletion by fluorescence in-situ hybridization analysis and P16 immunohistochemistry in malignant pleural mesothelioma in Egyptian patients

Background Malignant pleural mesothelioma (MPM) is an aggressive cancer caused basically by environmental exposure to asbestos and has limited overall treatment options and poor prognosis. The current standard diagnosis of MPM requires the testing of multiple immunohistochemical (IHC) markers on formalin-fixed paraffin-embedded tissue to differentiate MPM from other lung malignancies. Owing to the lack of a single, accurate IHC biomarker for MPM, recent studies have focused on identifying new diagnostic modalities. Objective Homozygous deletion of 9p21 is one of the most common genetic alterations in malignant mesotheliomas. In this work, we evaluated homozygous 9p21 (p16/CDKN2A) deletion by fluorescence in-situ hybridization (FISH) analysis in Egyptian patients with MPM using paraffin-embedded tissue specimens. We also studied the status of p16 expression by IHC, and results of both were analyzed separately and in relation to each other. Patients and methods Thoracoscopic pleural or true-cut needle biopsies from 42 cases of primary MPM were examined pathologically on routine hematoxylin and eosin histology. Age-matched and sex-matched 12 cases diagnosed as having nonmesothelioma diseases were included as controls. IHC markers to differentiate epithelioid MPM from metastatic lung adenocarcinoma were Carcino Embryonic Antigen (CEA) and calretinin. Representative tissue blocks were selected for p16 expression by IHC and 9p21 deletion by FISH. Results Deletion of 9p21 was demonstrated in 39 (92.8%) of 42 MPM cases, whereas it was not detected in any of the controls (P=0.002). Evaluating the diagnostic accuracy of P16 detected by FISH showed a positive sensitivity of 92.8%, specificity of 100%, and a power of performance of 0.93, with an overall accuracy to classify MPM correctly of 94.4%. However, p16 inexpression by IHC showed a sensitivity of 57.1%, specificity of 25%, with a very low power of performance of −0.1, and an overall accuracy of 50%. The discrepancy between the results of both techniques was analyzed. Conclusion Detection of homozygous p16 deletion by FISH is more sensitive and specific to distinguish MPM from others compared with IHC p16 inexpression and may represent an alternative diagnostic tool for MPM, especially in challenging cases. IHC p16 may be of prognostic value.

Combined modality treatment for malignant pleural mesothelioma: a single-centre long-term survival analysis using extrapleural pneumonectomy.

Combined modality treatment (CMT) for malignant pleural mesothelioma (MPM) remains a matter of debate regarding the choice of surgical procedure: extrapleural pneumonectomy (EPP) or pleurectomy/decortication. We performed a prospective interventional cohort study between 2003 and 2014. All consecutive patients with any histological MPM subtype, ≤70 years old, World Health Organization performance status ≤1, medically fit for pneumonectomy and stage cT1-2cN0-2cM0 (TNM7) or lower were included. Eligibility for CMT was discussed by the multidisciplinary tumour board. Our local CMT protocol consisted of induction chemotherapy, followed by EPP and hemithoracic radiotherapy. Induction chemotherapy consisted of 3 cycles of cisplatin (75 mg/m2 day 1) and pemetrexed (500 mg/m2 day 1), each administered once every 3 weeks. If non-progressive, EPP was performed followed by hemithoracic radiotherapy (most frequently, intensity-modulated radiotherapy; dose 54 Gy/1.8 Gy ± boost). Feasibility and long-term survival analyses were performed. Overall survival and disease-free survival (DFS) were calculated from histological confirmation of a diagnosis of MPM. Out of 197 patients, 97 started with CMT (79 epithelioid, 15 mixed and 3 sarcomatoid tumours, based on histological analysis). Clinical TNM was IA (n = 9)/IB (n = 8)/II (n = 57)/III (n = 23). A total of 76 patients underwent surgery (EPP: n = 56; exploratory thoracotomy: n = 20). The in-hospital mortality rate was 3.6%. Out of 56 patients who underwent surgery, 47 completed the entire CMT protocol. The intent-to-treat median and 5-year OS were 22.4 [95% confidence interval (CI) = 15.5-27.9] months and 11.2% (95% CI = 6.9-23.4). In patients who completed the CMT protocol (n = 47), these values were 33.2 (95% CI = 23.0-45.0) months and 24.2% (95% CI = 13.4-43.8). The intent-to-treat median and 5-year DFS were 15.6 (95% CI = 14.0-17.3) months and 9.9% (95% CI = 5.1-19.2), 19.8 (95% CI = 16.8-27.7) months and 17.2% (95% CI = 8.6-34.1) in those who had the full CMT. The Cox proportional hazards model showed a significantly lower DFS in positive lymph nodes (HR 2.79, 95% CI=1.35-5.78; P=0.006). In 30 (64%) patients with epithelioid type MPM without positive lymph nodes (pN0) after EPP, the 5-year DFS was 27.0% (95% CI=14.1-51.7). CMT with EPP for MPM is feasible, with an acceptable surgical mortality rate, and results in a 5-year survival rate of 24%. Careful patient selection (staging and physical performance) is extremely important.

Integrative Molecular Characterization of Malignant Pleural Mesothelioma.

Malignant pleural mesothelioma (MPM) is a highly lethal cancer of the lining of the chest cavity. To expand our understanding of MPM, we conducted a comprehensive integrated genomic study, including the most detailed analysis of BAP1 alterations to date. We identified histology-independent molecular prognostic subsets, and defined a novel genomic subtype with TP53 and SETDB1 mutations and extensive loss of heterozygosity. We also report strong expression of the immune-checkpoint gene VISTA in epithelioid MPM, strikingly higher than in other solid cancers, with implications for the immune response to MPM and for its immunotherapy. Our findings highlight new avenues for further investigation of MPM biology and novel therapeutic options. SIGNIFICANCE: Through a comprehensive integrated genomic study of 74 MPMs, we provide a deeper understanding of histology-independent determinants of aggressive behavior, define a novel genomic subtype with TP53 and SETDB1 mutations and extensive loss of heterozygosity, and discovered strong expression of the immune-checkpoint gene VISTA in epithelioid MPM.See related commentary by Aggarwal and Albelda, p. 1508.This article is highlighted in the In This Issue feature, p. 1494.

Moderately Hypofractionated Helical IMRT, FDG–PET/CT-guided, for Progressive Malignant Pleural Mesothelioma in Patients With Intact Lungs

IntroductionThe objective of this study was to present the outcomes of moderately hypofractionated helical intensity-modulated radiation therapy (HT) with/without simultaneous integrated boost (SIB) on fluorodeoxyglucose-positron emission tomography (FDG-PET) positive areas (gross tumor volume [GTV]-PET) for patients with progressive malignant pleural mesothelioma (MPM) after previous treatments. Methods and MaterialsFrom May 2006 to April 2014, 51 patients with a median age of 68.8 years (range, 38.6-82 years) were treated. There were 41 men and 10 women; 43 epithelioid MPM and 8 sarcomatoid, involving the left pleura in 25 patients and the right pleura in 26 patients. The initial stage was: I, 11 patients; II, 14 patients; III, 17 patients; and IV, 9 patients. Chemotherapy was prescribed for 46 patients, for 6 cycles (range, 0-18 cycles). Eighteen patients had pleurectomy/decortication, and 33 had talc pleurodesis. FDG-PET was used for target identification. A median dose of 56 Gy/25 fractions was prescribed to the involved pleura, and SIB to 62.5 Gy to GTV-PET was added in 38 patients. ResultsThe median survival from diagnosis was 25.8 months (range, 8.4-99.0 months). One patient, treated with SIB, was alive at the October 2017 follow-up. Two cases of grade 5 radiation pneumonitis were registered. A GTV-PET ≤ 205 cc was predictive of late ≥ grade 2 lung toxicity, but also of better survival in stage III and IV disease: 5.9 versus 11.7 months (P = .04). A GTV-PET ≥ 473 cc was predictive of early death (P = .001). ConclusionsModerately hypofractionated, FDG-PET guided salvage HT in patients with progressive MPM after previous treatments showed acceptable toxicity and outcome results similar to adjuvant radiotherapy after pleurectomy/decortication, suggesting that the delay of radiotherapy is not detrimental to survival, and has the associated benefit of postponing inherent toxicity.

Nuclear grading, BAP1, mesothelin and PD-L1 expression in malignant pleural mesothelioma: prognostic implications

For malignant pleural mesothelioma (MPM), histopathological subtype is one of the most important prognostic factors. Several immunohistochemical stains whose expressions have possible therapeutic implications have been identified in MPM such as BAP1, mesothelin and PD-L1. The aim of our work was to evaluate the clinical significance and prognostic implications of BAP1, mesothelin and PD-L1 expression in 117 patients with a diagnosis of MPM who were diagnosed in our institution between 2002 and 2017. We also correlated this immunohistochemical profile to a recently described nuclear grading and to histopathological subtype. Mesothelin expression, BAP1 loss and PD-L1 expression were associated with histopathological subtype (p<0.0001), BAP1 loss was more frequent in epithelioid subtype whereas PD-L1 expression was more frequent in non-epithelioid subtype. For epithelioid MPM, BAP1 expression was associated with overall survival (p=0.034), with a longer survival when BAP1 expression is lost. Necrosis and nuclear grading are associated with overall survival (p=0.0048 and <0.0001, respectively), with longer survival when necrosis was absent and for grade I. For non-epithelioid MPM, overall survival was not related to clinical, histopathological or immunohistochemical expression of BAP1, mesothelin or PD-L1. In multivariate analysis, grade I for nuclear grading was an independent prognostic factor associated with overall survival (p<0.0001). In epithelioid and non-epithelioid MPM, we analysed overall survival in subgroups with combined mesothelin, BAP1 and PD-L1 expression. In epithelioid MPM, BAP1 retained/mesothelin negativity/PD-L1>1%, and BAP1 retained/mesothelin positivity/PD-L1>1% profiles, are associated with shorter overall survival. In non-epithelioid MPM, BAP1 loss/mesothelin negativity/PD-L1>1% is associated with shorter overall survival. Our work confirms that nuclear grading in epithelioid MPM is a strong and independent prognosis factor. Moreover, this study on several promising immunohistochemical stains whose expressions have possible therapeutic implications identifies subgroups with a poor prognosis.

Pembrolizumab as Palliative Immunotherapy in Malignant Pleural Mesothelioma

IntroductionThere is no approved second-line treatment for malignant pleural mesothelioma (MPM). On the basis of promising early results, pembrolizumab was used off-label in Switzerland and Australia. We investigated outcomes in association with clinicopathological features and expression of programmed death ligand 1 (PD-L1). MethodsRegistry data in Australia and Switzerland were pooled. Patient characteristics, including age, sex, histological subtype, and previous treatments were captured. Outcomes were assessed locally. PD-L1 expression was categorized as negative (<5%), intermediate (5%-49%), and high (≥50%). ResultsA total of 93 patients (48 from Switzerland and 45 from Australia) were treated; 68 patients (73%) had epithelioid MPM, and 67 (72%) had an Eastern Cooperative Oncology Group performance status of 0 or 1. Pembrolizumab was the second-line treatment in 48 of 93 patients (52%). PD-L1 expression results were available for 66 patients (71%). Most (68%) were negative, 18% were intermediate, and 14% were high for PD-L1 expression. In the full cohort, the overall response rate (ORR) was 18%, the median progression-free survival (mPFS) was 3.1 months, and the median overall survival was 7.2 months. In patients with an Eastern Cooperative Oncology Group performance status of 0 or 1 and only one previous systemic treatment (n = 35), the ORR was 37%, the mPFS was 3.7 months, and the median overall survival was 10.2 months. The nonepitheloid histological subtype showed an improved ORR (24% versus 16% [p = 0.54) and mPFS (5.6 versus 2.8 months [p = 0.02]). Compared with intermediate and negative PD-L1 expression, high PD-L1 expression was associated with an improved ORR (44% versus 42% versus 11% [p = 0.01]) and mPFS (6.2 versus 3.9 versus 2.7 months [p = 0.04]). Toxicity was as expected. ConclusionThese real-world data demonstrate similar response rates but inferior survival compared with those in early-phase trials. High PD-L1 expression and nonepitheloid histological subtype were associated with greater activity. Anti–PD-L1 immunotherapy is a reasonable second-line therapy in patients with MPM.

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

ObjectiveTo understand the relationship between response and survival in malignant pleural mesothelioma (MPM). Patients and MethodsThe 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. ResultsPatients 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. ConclusionOur 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.

Reproducibility of Malignant Pleural Mesothelioma Histopathologic Subtyping.

- Malignant pleural mesothelioma (MPM) is a rare tumor with poor prognosis. Several studies have analyzed potential prognostic markers, but histologic type remains the single most important prognostic factor. Histologic subtypes of epithelioid MPM seem to have prognostic and therapeutic implications. Interobserver agreement in histologic pattern classification should be high. - To assess interobserver and intraobserver reproducibility in histologic differentiation between the main types of MPMs, and in further subtyping of epithelioid-type mesothelioma. - One representative hematoxylin-eosin-stained slide was selected from the archive for each of 200 patients with MPM. They were reviewed independently by 3 pathologists and classified according to the current World Health Organization classification of pleural tumors. After the first round of evaluations, a consensus meeting was organized where problems were addressed and representative images for each histologic category were selected. Two months later, cases were reevaluated by all 3 pathologists. - After the first round, overall interobserver agreement for histologic subtyping of mesothelioma was fair (κ, 0.36). The agreement was increased to substantial (κ, 0.63) in the second round. Improvement was found in interobserver agreement for all types of MPM and for most epithelioid subtypes. - Moderate to substantial agreement in histologic typing and subtyping of MPM can be achieved. However, training with additional clarification of diagnostic criteria, their strict application, and help from consensus-based illustrative images is needed.

FGF2 and EGF induce epithelial-mesenchymal transition in malignant pleural mesothelioma cells via a MAPKinase/MMP1 signal.

Malignant pleural mesothelioma (MPM), an aggressive malignancy affecting pleural surfaces, occurs in three main histological subtypes. The epithelioid and sarcomatoid subtypes are characterized by cuboid and fibroblastoid cells, respectively. The biphasic subtype contains a mixture of both. The sarcomatoid subtype expresses markers of epithelial-mesenchymal transition (EMT) and confers the worst prognosis, but the signals and pathways controlling EMT in MPM are not well understood. We demonstrate that treatment with FGF2 or EGF induced a fibroblastoid morphology in several cell lines from biphasic MPM, accompanied by scattering, decreased cell adhesion and increased invasiveness. This depended on the MAP-kinase pathway but was independent of TGFβ or PI3-kinase signaling. In addition to changes in known EMT markers, microarray analysis demonstrated differential expression of MMP1, ESM1, ETV4, PDL1 and BDKR2B in response to both growth factors and in epithelioid versus sarcomatoid MPM. Inhibition of MMP1 prevented FGF2-induced scattering and invasiveness. Moreover, in MPM cells with sarcomatoid morphology, inhibition of FGF/MAP-kinase signaling induced a more epithelioid morphology and gene expression pattern. Our findings suggest a critical role of the MAP-kinase axis in the morphological and behavioral plasticity of mesothelioma.

Effects of combined therapies on the survival of pleural mesothelioma patients treated in Brescia, 1982-2006.

During the 1990's, the traditional unimodal treatments (surgery, radiotherapy, chemotherapy, immunotherapy) for malignant pleural mesothelioma started to be combined in bimodal or multimodal strategies. However, recent population-based analyses of the survival of patients with malignant pleural mesothelioma indicate that even these treatments have not led to significant improvements in prognosis, which remains very poor. The present study assessed the survival of patients given combined treatments and multimodal therapies in a specialized hospital department. The study population comprised 530 patients diagnosed with malignant pleural mesothelioma from 1982 to 2006: 343 of them were residents in the province of Brescia (Lombardy, Northern Italy) and 187 were residents outside the province, with a follow-up to 31 December 2009. Kaplan-Meier survival analyses and Cox proportional risks model were used to test sex, age at diagnosis, histological type and treatments, as prognostic factors. The estimated median survival for the whole group of patients was 317 days (257 for residents and 398 for non-residents), and respectively 310 and 340 days in the groups diagnosed in the periods 1982-2000 and 2001-2006. Multivariate analysis confirmed that the prognosis was better for younger patients and cases of epithelioid type malignant pleural mesothelioma, whereas for patients receiving any single treatment the prognosis was not significantly better than for those given palliative care alone. However, patients receiving combined treatments or the multimodality approach had significantly longer median survival and the relative risk of death was respectively 0.57 and 0.61 compared to untreated patients (or those only given symptomatic therapy). This is the first study in Italy to assess the effectiveness of different treatment approaches in a significant number of patients treated in one hospital. Further studies are needed to confirm the improvement in prognosis - even if modest--on larger numbers of patients and taking into account the different stages of the disease.

Nuclear grade and necrosis predict prognosis in malignant epithelioid pleural mesothelioma: a multi-institutional study.

A recently described nuclear grading system predicted survival in patients with epithelioid malignant pleural mesothelioma. The current study was undertaken to validate the grading system and to identify additional prognostic factors. We analyzed cases of epithelioid malignant pleural mesothelioma from 17 institutions across the globe from 1998 to 2014. Nuclear grade was computed combining nuclear atypia and mitotic count into a grade of I-III using the published system. Nuclear grade was assessed by one pathologist for three institutions, the remaining were scored independently. The presence or absence of necrosis and predominant growth pattern were also evaluated. Two additional scoring systems were evaluated, one combining nuclear grade and necrosis and the other mitotic count and necrosis. Median overall survival was the primary endpoint. A total of 776 cases were identified including 301 (39%) nuclear grade I tumors, 354 (45%) grade II tumors and 121 (16%) grade III tumors. The overall survival was 16 months, and correlated independently with age (P=0.006), sex (0.015), necrosis (0.030), mitotic count (0.001), nuclear atypia (0.009), nuclear grade (<0.0001), and mitosis and necrosis score (<0.0001). The addition of necrosis to nuclear grade further stratified overall survival, allowing classification of epithelioid malignant pleural mesothelioma into four distinct prognostic groups: nuclear grade I tumors without necrosis (29 months), nuclear grade I tumors with necrosis and grade II tumors without necrosis (16 months), nuclear grade II tumors with necrosis (10 months) and nuclear grade III tumors (8 months). The mitosis-necrosis score stratified patients by survival, but not as well as the combination of necrosis and nuclear grade. This study confirms that nuclear grade predicts survival in epithelioid malignant pleural mesothelioma, identifies necrosis as factor that further stratifies overall survival, and validates the grading system across multiple institutions and among both biopsy and resection specimens. An alternative scoring system, the mitosis-necrosis score is also proposed.

AB016. Pleurectomy/decortication for malignant pleural mesothelioma

AB016. Pleurectomy/decortication for malignant pleural mesothelioma

Resveratrol induces cell cycle arrest and apoptosis in epithelioid malignant pleural mesothelioma cells

Abstract Background Resveratrol is a natural anti-carcinogenic polyphenol. Malignant pleural mesothelioma (MPM) is an aggressive tumor with poor prognosis. In this study, we investigated the effects of resveratrol on epithelioid MPM. Material and methods Human epithelioid MPM cell line (NCI-H2452) was exposed to resveratrol (5–200 μM) for 24 or 48 h. Cell viability was assessed by WST-1 assay. Flow cytometry analyses were performed to evaluate the effects of resveratrol on cell cycle distribution and apoptosis. Western blot analysis was used to determine protein expression levels of antioxidant enzymes, cyclin D1 and p53. Reactive oxygen species (ROS) were measured using H2DCFDA. Results Resveratrol reduced cell viability of the cells in a concentration and time dependent manner. After treatment, the cells accumulated in G0/G1 phase and the percentage of cells in G2/M phase was reduced. Resveratrol decreased cyclin D1 and increased p53 expression in cell lysates. Treated cells exhibited increased apoptotic activity. ROS were elevated with resveratrol treatment, but there was no change in the expression of superoxide dismutase (SOD)-1, SOD-2 and glutathione peroxidase. Conclusion Our results revealed that resveratrol exhibits anti-cell viability effect on epithelioid MPM cells by inducing cell cycle arrest and apoptosis. Resveratrol may become a potential therapeutic agent for epithelioid MPM.

Diaphragm and lung–preserving surgery with hyperthermic chemotherapy for malignant pleural mesothelioma: A 10-year experience

BackgroundThe best surgical treatment for malignant pleural mesothelioma is still under a debate, but recent evidence points toward a less-invasive approach to reduce morbidity and mortality. We reported our 10-year experience of a limited surgical approach associated with hyperthermic intrathoracic chemotherapy (HITHOC). Material and MethodsBetween 2005 and 2014, patients with epithelioid or biphasic malignant pleural mesothelioma were treated with lung–diaphragm–pericardium-sparing pleurectomy associated with double-drug HITHOC; at least 3 cycles of adjuvant chemotherapy were then administered. The primary outcome examined was the feasibility of the procedure, whereas secondary outcomes were overall survival and disease-free interval. ResultsAmong 49 patients, 41 were male. Median age was 68 years (35-76 years). Histology was epithelioid in 43 cases. Pathologic stage I, II, III, and IV occurred in 12, 14, 20, and 3 cases, respectively. No intraoperative complications or postoperative mortality occurred, whereas morbidity rate was 46.9%. Median hospital stay was 8 days (5-45 days). Actuarial median overall survival was 22 months and a 1-, 2-, and 5-year survival accounted for 79.6%, 45.7%, and 9.9%, respectively. Disease-free survival after surgery was 62%, 37.5%, and 18.5% at 1, 2, and 5 years, respectively. Risk factors analysis for overall survival confirmed a significant role for early stages, epithelioid histology, and fibrinogen serum levels. ConclusionsCytoreductive surgery associated with HITHOC and adjuvant chemotherapy appears feasible and safe, with no mortality and low morbidity. Preserving lung and diaphragmatic function might warrant an acceptable long-term outcome.

SPS-7 - Nintedanib plus pemetrexed/cisplatin in patients with MPM: Phase II findings from the placebo-controlled LUME-Meso trial

Standard 1st-line treatment for patients (pts) with unresectable malignant pleural mesothelioma (MPM) is pemetrexed/cisplatin (PEM/CIS); median overall survival (OS) is approximately 1 year. Nintedanib (N) is an oral inhibitor of VEGFR, PDGFR and FGFR, and Src and Abl kinases. VEGF and PDGF overexpression are associated with poor prognosis in MPM, and N has shown efficacy in preclinical models. This study evaluated the efficacy and safety of N+PEM/CIS vs placebo (P)+PEM/CIS in pts with MPM. Pts with unresectable MPM (chemo-naive, ECOG PS 0-1) were stratified by histology (epithelioid/biphasic) and randomised 1:1 to receive up to 6 cycles of PEM (500 mg/m2)/CIS (75 mg/m2) on Day 1 plus N or P (200 mg bid) on Days 2-21. Pts without disease progression received maintenance N or P. The primary endpoint was progression-free survival (PFS). 87 pts were randomised to N+PEM/CIS (n = 44) or P+PEM/CIS (n = 43). Pt characteristics were comparable between the groups; 89% had epithelioid MPM. PFS was significantly improved with N vs P (HR = 0.56 [95% CI 0.34-0.91]; p = 0.0174; median PFS 9.4 vs 5.7 months). PFS benefit was also seen in the epithelioid subgroup (HR = 0.51 [95% CI 0.30-0.86]; p = 0.0101). Preliminary OS data favoured N; objective tumour response was observed in 59% of the N arm vs 44% of the P arm (all partial responses). All pts experienced at least one adverse event (AE; any grade), with 7% of the N arm discontinuing due to AEs vs 15% with P. Serious AEs occurred in 36% vs 42% of pts in the N and P arms, respectively. The most common Grade ≥3 AEs (N vs P) were neutropenia (34% vs 10%), alanine aminotransferase increase (14% vs 2%) and gamma glutamyltransferase increase (14% vs 0%). N+PEM/CIS demonstrated clinical efficacy with improved PFS and a tolerable safety profile in pts with unresectable MPM. Based on these promising findings, the study was extended and the Phase III part is recruiting (NCT01907100).

Cancer antigen profiling for malignant pleural mesothelioma immunotherapy: expression and coexpression of mesothelin, cancer antigen 125, and Wilms tumor 1.

BackgroundTo develop cancer antigen-targeted immunotherapeutic strategies for malignant pleural mesothelioma (MPM), we investigated the individual and coexpressions of the cancer-associated antigens mesothelin (MSLN), cancer antigen 125 (CA125), and Wilms tumor 1 (WT1) in both epithelioid and non-epithelioid MPM.MethodsAll available hematoxylin and eosin-stained slides from patients who were diagnosed with MPM (1989-2010) were reviewed. We constructed tissue microarrays from 283 patients (epithelioid = 234; non-epithelioid = 49). Intensity and distribution for each antigen were assessed by immunohistochemistry.ResultsPositive expression of MSLN, CA125, and WT1 were demonstrated in 93%, 75%, and 97% of epithelioid MPM cases, and 57%, 33%, and 98% of non-epithelioid MPM cases, respectively. Triple- and double-positive antigen coexpressions were demonstrated in 72% and 23% of epithelioid MPM cases and 29% and 33% of non-epithelioid MPM cases, respectively. Complete absence of expression for all three antigens was demonstrated in <2% of MPM cases. More than two-thirds of MPM cases had ≥50% distribution of MSLN-positive cells and, among the remaining third, half had ≥50% distribution of WT1-positive cells. CA125/MSLN coexpression was observed in more than two-thirds of epithelioid MPM cases and one-third of non-epithelioid MPM cases.ConclusionA limited number of cancer-associated antigens can target almost all MPM tumors for immunotherapy.

Association Between Clinicopathological Factors and Genomic Abnormalities Detected by FISH Analysis in Epithelioid Diffuse Malignant Pleural Mesothelioma.

Abnormality of genes including 9p21 is known in malignant mesothelioma and we have examined the frequency of gene deletion and amplification using the fluorescence in situ hybridization (FISH) method. We formerly reported that abnormality of the genes was more common in the sarcomatoid type than epithelioid type. In this study, we compared the clinicopathological factors including nuclear grade (NG) and genomic abnormality in epithelioid malignant pleural mesothelioma (MPM). Using paraffin-embedded tissues of 31 epithelioid MPMs, we investigated the presence of gene abnormalities in the genes 9p21, 1p36, 14q32, 22q12, 5p15, 6p, 8q24, and 7p12 by the FISH method, and compared the results with NG, clinical stage, and prognosis. In the higher NG group of epithelioid MPM, more gene amplifications [in particular 5p15 and 8q24(MYC)] were observed, and clinical stage was more advanced. Cases with the amplification of 7p12(EGFR) tended to exhibit a worse prognosis. The significant correlation between histological differentiation and clinical features such as prognosis was not confirmed. NG status in epithelioid MPM may be related to gene alteration and clinical features.

Novel prognostic markers for epithelioid malignant pleural mesothelioma.

e20028 Background: Malignant pleural mesothelioma (MPM) is a deadly asbestos related tumour. The median survival is about 12 months and MPM patients are usually offered with a multimodality approach. With regard to chemotherapy the treatment of choice is the antifolate pemetrexed in combination with cisplatin or carboplatin. The high variability in the survival of patients with similar characteristics make it challenging to identify reliable prognostic markers. In this study we sought novel prognostic markers for epithelioid MPM, by investigating the expression levels of 117 genes involved in cancer. Methods: Gene expression analysis was evaluated on RNA from 15 epithelioid MPM patients undergoing pleurectomy (fomalin-fixed paraffin-embedded tissue) using a custom panel on nanoString platform. All patients were treated with cisplatin plus pemetrexed chemotherapy. Patients were divided in two groups for each gene (high and low expression level) on the basis of median. The correlation between gene expression, overall survival (OS) and progression free survival (PFS) was carried out by Log-rank test (Kaplan Meier). Results: A poorer OS was associated with a higher expression of 3 genes: MCM2 (p-value 0.005), PLK1 (p-value 0.005) and CCNB2 (p-value 0.01). These findings were in agreement with TCGA data ( PROGgeneV2: enhancements on the existing database. BMC Cancer 2014). Moreover, PLK1 showed a significant correlation also with PFS (p-value 0.01). Conclusions: Several biomarkers have been suggested as MPM prognostic factors, but sensitive and specific ones for the clinical practice are still missing. Despite the relatively small number of tissue samples, related to the rarity of this tumour, we identified 3 genes as potential prognostic markers. MCM2 is involved in the initiation of genome replication, PLK1 and CCNB2 regulate cell cycle by promoting mitosis. All these genes proved to be not only useful prognostic indicators but also promising therapeutic targets as reported in functional studies on different cancer models. The validation of these new markers, particularly of PLK1 which is correlated also with PFS, may improve the prognostic stratification at diagnosis, providing information valuable in the management of MPM patients.

Trabectedin (T) as second line treatment option for patients with epithelioid malignant pleural mesothelioma (MPM) in progression following pemetrexed/platin-derivates chemotherapy: ATREUS trial.

8513 Background: Systemic chemotherapy in MPM is inevitably followed by relapse, and response rates to second line treatment are limited. T is an antineoplastic agent targeting both the malignant cells and the tumor microenvironment with demonstrated activity against a range of tumors. We aimed to study the activity and safety of T in advanced MPM. Methods: ATREUS, an Italian multicenter single arm phase II trial, assessed the activity T in MPM evaluating the proportion of patients responding to treatment and achieving progression free survival for 12 weeks (PFS12w). Pre-treated epithelioid and naive or pre-treated biphasic/sarcomatoid pts were treated until progression or unacceptable toxicity. Initial dose was 1.3 mg/m2, over 3 hours every 21 days, later reduced to 1.1 mg/m2to improve tolerability. In the epithelioid cohort, sample size was based on a Simon's Optimal Two-Stage Design. The study was set to reject, at an alpha error of 10% the hypothesis that PFS12w was ≤25% and to demonstrate, with a power of 85% the hypothesis that PFS12w was ≥40%. At least 20 out of 62 pts with assessed disease, no major protocol violations, either receiving ≥12 weeks of treatment or interrupting before for progression or death (per protocol – PP analysis) were to reach PFS12w in order to consider T effective. Results: 71 pts were enrolled and evaluable. Average age was 65.8 ± 8.75 years. 71.8% were male and 82.5% presented stage III or IV disease. 42.4% (25/59) of pts included in the PP analysis obtained PFS12w (95% CI: 29.6% - 55.9%). In a second, more conservative analysis, including pts withdrawn prematurely for toxicity or intercurrent illness as failures, PFS12w rate reached 38.5% (25/65 pts). The most frequent grade ≥3 treatment-related toxicities werehepatic toxicity (60.5%), non-febrile neutropenia (21.1%), and fatigue (6.6%). Five pts (7%) interrupted treatment for toxicities (2 liver, 1 multi-organ failure, 1 thrombocytopenia, 1 T intolerance). Conclusions: In pts with advanced epithelioid MPM, second line treatment with T showed an elevated rate of disease stabilization. Safety data is promising but require further evaluation. Clinical trial information: NCT02194231.

Patterns of metastases in malignant pleural mesothelioma in the modern era: Redefining the spread of an old disease.

8556 Background: Malignant pleural mesothelioma (MPM) has been historically documented as a locally infiltrative disease in large series from the early 1980s. With the changing landscape of cancer diagnosis and treatment, increased areas of unusual metastases have been published as case reports. With no standard second-line therapies for MPM, referral to early phase trial units is common. We report the metastatic patterns of a large cohort of MPM patients treated at the Royal Marsden Drug Development Unit (DDU). Methods: Clinical data was gathered for MPM patients referred to the DDU from 1992 to 2016. Radiographic details were collected from CT, bone scan and FDG PET imaging. Prior treatment, response, somatic mutations, clinical trial and survival data was obtained from medical records. Results: From the database, 165 evaluable patients with MPM were identified. Median age at diagnosis was 64 years (range 37–90) and 76% were male. Epithelioid MPM comprised 81% and 65% were right sided. Bone metastases were reported in 20%, with the majority lytic in nature ( Table). Peritoneal and omental disease was evident in 24% with ascites in 16%. In 11% of cases lung metastases presented as diffuse miliary-type pattern. Visceral metastases (15%) were predominantly liver (78%), but also occurred in adrenals, spleen and kidneys. Symptomatic brain metastases were recorded in 3%. Median overall survival was 24.2 months (95% CI: 20.8 - 29.2). Conclusions: This large study documents the metastatic patterns of advanced MPM in the 21st century and highlights an increased frequency of traditionally unexpected sites of metastases. Higher than expected incidence of lytic bone metastases (20%) suggests consideration of bone imaging in advanced MPM clinical workflow and trial protocols. [Table: see text]