Jenette Creaney

Mesothelin-family proteins and diagnosis of mesothelioma

BACKGROUND Mesothelioma is a highly aggressive tumour for which there are no reliable serum tumour markers. Identification of such a marker would be useful in diagnosis of mesothelioma and for monitoring responses to treatment and screening at-risk individuals. METHODS We assayed serum concentrations of soluble mesothelin-related proteins (SMR) using a double determinant (sandwich) ELISA in a blinded study of serum samples from 44 patients with histologically proven mesothelioma; 68 matched healthy controls, 40 of whom had been exposed to asbestos; and 160 patients with other inflammatory or malignant lung and pleural diseases. FINDINGS 37 (84%) of 44 patients with mesothelioma had raised concentrations of SMR at a serum dilution of 1/80, compared with three (2%) of 160 patients with other cancers or other inflammatory lung or pleural diseases, and with none of 28 controls who had not been exposed to asbestos. SMR concentrations correlated with tumour size and increased during tumour progression. Seven of the 40 asbestos-exposed individuals had increased serum concentrations of SMR; three of those seven developed mesothelioma and one developed lung carcinoma within 1-5 years. None of the 33 asbestos-exposed participants whose serum samples had normal concentrations of SMR and who were followed up over 8 years developed mesothelioma. INTERPRETATION Determination of SMR in serum could be a useful marker for diagnosis of mesothelioma and to monitor disease progression. It might also prove helpful for screening asbestos-exposed individuals for early evidence of mesothelioma.

The nuclear deubiquitinase BAP1 is commonly inactivated by somatic mutations and 3p21.1 losses in malignant pleural mesothelioma.

Malignant pleural mesotheliomas (MPMs) often show CDKN2A and NF2 inactivation, but other highly recurrent mutations have not been described. To identify additional driver genes, we used an integrated genomic analysis of 53 MPM tumor samples to guide a focused sequencing effort that uncovered somatic inactivating mutations in BAP1 in 23% of MPMs. The BAP1 nuclear deubiquitinase is known to target histones (together with ASXL1 as a Polycomb repressor subunit) and the HCF1 transcriptional co-factor, and we show that BAP1 knockdown in MPM cell lines affects E2F and Polycomb target genes. These findings implicate transcriptional deregulation in the pathogenesis of MPM.

Serum Mesothelin for Diagnosing Malignant Pleural Mesothelioma: An Individual Patient Data Meta-Analysis

PURPOSE Mesothelin is currently considered the best available serum biomarker of malignant pleural mesothelioma. To examine the diagnostic accuracy and use of serum mesothelin in early diagnosis, we performed an individual patient data (IPD) meta-analysis. METHODS The literature search identified 16 diagnostic studies of serum mesothelin, measured with the Mesomark enzyme-linked immunosorbent assay. IPD of 4,491 individuals were collected, including several control groups and 1,026 patients with malignant pleural mesothelioma. Mesothelin levels were standardized for between-study differences and age, after which the diagnostic accuracy and the factors affecting it were examined with receiver operating characteristic (ROC) regression analysis. RESULTS At a common diagnostic threshold of 2.00 nmol/L, the sensitivities and specificities of mesothelin in the different studies ranged widely from 19% to 68% and 88% to 100%, respectively. This heterogeneity can be explained by differences in study population, because type of control group, mesothelioma stage, and histologic subtype significantly affected the diagnostic accuracy. The use of mesothelin in early diagnosis was evaluated by differentiating 217 patients with stage I or II epithelioid and biphasic mesothelioma from 1,612 symptomatic or high-risk controls. The resulting area under the ROC curve was 0.77 (95% CI, 0.73 to 0.81). At 95% specificity, mesothelin displayed a sensitivity of 32% (95% CI, 26% to 40%). CONCLUSION In patients suspected of having mesothelioma, a positive blood test for mesothelin at a high-specificity threshold is a strong incentive to urge further diagnostic steps. However, the poor sensitivity of mesothelin clearly limits its added value to early diagnosis and emphasizes the need for further biomarker research.

Soluble mesothelin in effusions - a useful tool for the diagnosis of malignant mesothelioma

Background: The diagnosis of malignant mesothelioma is frequently difficult, the most common differential diagnosis being reactive pleural conditions and metastatic adenocarcinoma. Soluble mesothelin levels in serum have recently been shown to be highly specific and moderately sensitive for mesothelioma. As most patients with mesothelioma present with exudative effusions of either the pleura or the peritoneum, a study was undertaken to determine if levels of mesothelin were raised in these fluids and if the increased levels could help to distinguish mesothelioma from other causes of exudative effusion. Methods: Pleural fluid was collected from 192 patients who presented to respiratory clinics (52 with malignant mesothelioma, 56 with non-mesotheliomatous malignancies and 84 with effusions of non-neoplastic origin). Peritoneal fluid was collected from 42 patients (7 with mesothelioma, 14 with non-mesotheliomatous malignancies and 21 with benign effusions). Mesothelin levels were determined in effusion and serum samples by ELISA. Results: Significantly higher levels of mesothelin were found in effusions of patients with mesothelioma; with a specificity of 98%, the assay had a sensitivity of 67% comparing patients with mesothelioma and those with effusions of non-neoplastic origin. In 7 out of 10 cases mesothelin levels were raised in the effusion collected 3 weeks to 10 months before the diagnosis of mesothelioma was made; in 4 out of 8 of these, mesothelin levels were increased in the effusion but not in the serum. Conclusions: Measurement of mesothelin concentrations in the pleural and/or peritoneal effusion of patients may aid in the differential diagnosis of mesothelioma in patients presenting with effusions.

Comparison of Osteopontin, Megakaryocyte Potentiating Factor, and Mesothelin Proteins as Markers in the Serum of Patients with Malignant Mesothelioma

Introduction: There is increasing interest in identifying a blood-based marker for the asbestos-related tumor, malignant mesothelioma. Three potential markers for mesothelioma are mesothelin, megakaryocyte potentiating factor (MPF) and osteopontin. The purpose of the current study was to directly compare these biomarkers in the same sample population, determining their sensitivity and specificity in establishing a diagnosis, and to determine if diagnostic accuracy for mesothelioma is improved by combining the data from all three markers. Methods: Serum levels of mesothelin, MPF and osteopontin were determined by commercially available assays in 66 samples from patients with pleural malignant mesothelioma, 20 healthy individuals, 21 patients with asbestos-related lung or pleural disease, 30 patients presenting with benign pleural effusions and 30 patients with other malignancies. Results: Serum levels of the three markers were elevated in mesothelioma patients. At a level of specificity of 95% relative to healthy controls and patients with benign asbestos related disease, the sensitivity for mesothelioma was 34% for MPF, 47% for osteopontin and 73% for mesothelin. Osteopontin and MPF were unable to differentiate patients with mesothelioma from patients with other malignancies or those presenting with transudative pleural effusions. Combining the data from the three biomarkers using a logistic regression model did not improve sensitivity for detecting mesothelioma above that of the mesothelin marker alone. Conclusion: Serum mesothelin remains the most specific marker for the diagnosis of mesothelioma.

Soluble mesothelin-related protein in an asbestos-exposed population: the dust diseases board cohort study.

RATIONALE Soluble mesothelin-related protein (SMRP) is raised in epithelial-type malignant mesothelioma (MM), but the utility of SMRP in screening for MM is unknown. OBJECTIVES We aimed to evaluate SMRP in an asbestos-exposed cohort. METHODS A total of 538 subjects were studied. Those with elevated SMRP (> or =2.5 nM) underwent further investigation including positron emission tomography/computed tomography. MEASUREMENTS AND MAIN RESULTS Mean (+/-SD) SMRP in healthy subjects exposed to asbestos (n = 223) was 0.79 (+/-0.45) nM. Fifteen subjects had elevated SMRP, of whom one had lung cancer, which was successfully resected. Another with lung cancer was undetected by SMRP. No subjects were diagnosed with MM. Mean SMRP in healthy subjects was significantly lower than in subjects with pleural plaques alone (P < 0.01). CONCLUSIONS This is the first large-scale prospective study of SMRP for screening for malignancy in asbestos-exposed individuals. A high false-positive rate was observed. SMRP seems unlikely to prove useful in screening for MM.

Serum Soluble Mesothelin Concentrations in Malignant Pleural Mesothelioma: Relationship to Tumor Volume, Clinical Stage and Changes in Tumor Burden

Purpose: To examine the clinical utility of soluble mesothelin in patients with malignant pleural mesothelioma. Experimental Design: A total of 97 patients (female: 11; male: 86) were prospectively enrolled, longitudinal serum samples collected, and mesothelin concentrations determined. Baseline mesothelin levels were analyzed relative to tumor stage, presence of metastatic disease, the positron emission tomography (PET) parameters maximum standardized uptake value, tumor volume, total glycolytic volume, and survival. Changes in mesothelin level were correlated to objective response to chemotherapy, as assessed radiologically and by PET imaging, and with patient survival. Results: Baseline mesothelin levels greater than 5 nmol/L were a significant negative prognostic indicator (HR = 2.25; 95% CI, 1.20–4.21) and correlated with tumor stage and volume. In 55 patients who received chemotherapy, change in mesothelin correlated with radiological response (χ2 = 11.32; P = 0.023) and change in metabolically active tumor volume (r = 0.58; P < 0.01). Median survival for patients with a reduction in mesothelin following chemotherapy (19 months) was significantly longer than for patients with increased mesothelin (5 months; P < 0.001). Conclusion: These findings show the potential value of changes in mesothelin levels for prognostication and monitoring of treatment response in mesothelioma. Clin Cancer Res; 17(5); 1181–9. ©2010 AACR.

Comparison of fibulin-3 and mesothelin as markers in malignant mesothelioma

Background Pleural malignant mesothelioma (MM) is a deadly tumour predominantly associated with asbestos exposure. A reliable diagnostic and prognostic marker for MM will significantly enhance clinical care and is an area of intense research. Soluble mesothelin is the most studied and an FDA-approved biomarker for MM. A recent report showed promising results using fibulin-3 as a new diagnostic marker. The aim of this study was to compare the utility of fibulin-3 versus mesothelin, singly or in combination. Methods Fibulin-3 and soluble mesothelin were determined by ELISA in the plasma and pleural fluid of 153 patients presenting with a pleural effusion including 82 with MM, 36 with non-MM malignant effusions and 35 with benign effusions. Biomarker concentrations were determined in the plasma of an additional 49 cases with benign asbestos-related disease. Results Mesothelin provides better diagnostic accuracy than fibulin-3 for MM whether measured in plasma or pleural effusion: area under the curve (AUC) for plasma was 0.822 (95% CI 0.76 to 0.87) compared with 0.671 (0.61 to 0.73), respectively, and for pleural fluid AUC was 0.815 (0.74 to 0.87) compared with 0.588 (0.51 to 0.67), respectively. Effusion fibulin-3 was an independent significant prognostic factor for survival in MM patients; HR 2.08 (1.14 to 3.82), p=0.017. MM patients with effusion fibulin-3 levels below the median survived significantly longer than those with levels above the median (14.1 vs 7.9 months, p=0.012). Mesothelin and neutrophil to lymphocyte ratio were not significant prognostic markers. Conclusions Soluble mesothelin is a superior diagnostic biomarker for MM compared with fibulin-3, whereas fibulin-3 provides superior prognostic information compared with mesothelin.

A diagnosis of malignant pleural mesothelioma can be made by effusion cytology: results of a 20 year audit

Aims: Cytological diagnosis of malignant pleural mesothelioma (MPM) is controversial, but has been used in our institution for over 30 years. To assess the role of effusion cytology in mesothelioma diagnosis we conducted an audit of pleural fluid cytology results over a 20 year period (1988–2007). Methods: Pleural samples were received from 6285 patients; data linkage with Western Australian Cancer and Mesothelioma Registries demonstrated that 815 of these patients had a diagnosis of MPM. Cytological examination of a pleural effusion specimen had been performed in 517 (63%) of these 815 patients. Results: Definitive cytological diagnosis of MPM was made in 377/517 cases, resulting in an ‘absolute’ sensitivity of 73%. An additional 66 patients were diagnosed as atypical/suspicious, resulting in a ‘complete’ sensitivity of 86%. If only biopsy/necropsy proven cases are considered, the absolute sensitivity is 68% and the complete sensitivity is 82%. There were no false positive diagnoses of malignancy; two patients with metastatic adenocarcinoma were initially diagnosed as MPM, prior to the availability of specific mesothelial markers, resulting in a positive predictive value of 99%. Conclusions: Effusion cytology is an inexpensive, minimally invasive procedure which should be included in the diagnostic work-up of cases of suspected MPM.

A Phase II Study of Intermittent Sunitinib Malate as Second-Line Therapy in Progressive Malignant Pleural Mesothelioma

Introduction: There is no accepted second-line therapy for patients with advanced malignant pleural mesothelioma (MPM), whose disease has progressed after first-line chemotherapy. The multitargeted tyrosine kinase inhibitor sunitinib malate targets several pathways overexpressed in mesothelioma. This phase II study assessed objective response to sunitinib and correlative biomarkers in patients with progressive pretreated MPM. Methods: Eligible patients had confirmed MPM, radiological progression after chemotherapy, Eastern Cooperative Oncology Group performance status 0 to 1, and measurable disease. Patients received oral sunitinib 50 mg daily for 28 of every 42 days. The primary endpoint was objective radiological response. Patients without prior pleurodesis had fluorodeoxyglucose positron emission tomographic response assessed by total glycolytic volume criteria. Correlative biomarkers included serum mesothelin, vascular endothelial growth factor (VEGF)-A, VEGF-C, interleukin-8, sVEGFR-2, sVEGFR-3, and s-kit. Results: Fifty-three patients received sunitinib between July 2006 and December 2009; 51 were assessable for response. Patients received a median of two cycles (range, 1–12); 40% required dose reduction. Fatigue was the most prominent toxicity. Six patients (12%) had a confirmed radiological partial response, 34 (65%) had stable disease, and 11 (22%) had progressive disease as best response. Six of 20 patients had a decrease in fluorodeoxyglucose positron emission tomographic total glycolytic volume of 15% or more. Median overall survival was 6.1 months, and median time to progression was 3.5 months. Correlative biomarkers did not predict treatment response. Conclusions: Sunitinib has activity in a subset of patients with pretreated MPM. Consideration should be given to different treatment schedules and examination of other biomarkers for further study of sunitinib in MPM.