Soluble Mesothelin-related Peptide Research Articles

Two Novel Polymorphisms in 5' Flanking Region of the Mesothelin Gene are Associated with Soluble Mesothelin-Related Peptide (SMRP) Levels

Increased concentrations of soluble mesothelin-related peptides (SMRP) have been found in sera of patients with malignant pleural mesothelioma (MPM) even if a relatively high rate of false positives has hampered their clinical use as a tumor marker. Individual SMRP levels could be affected by polymorphic elements. The aim of this study was to investigate the association between single nucleotide polymorphisms within the promoter-5'UTR regions and SMRP levels in healthy asbestos-exposed individuals and patients suffering from MPM.? The promoter-5'UTR regions of the mesothelin gene were genotyped in 59 healthy asbestos-exposed subjects and 27 MPM patients. SMRP levels were measured using a commercially available ELISA kit.? Two novel polymorphisms, an A>C variant (called New1) and a C>T variant (called New2), were identified. In healthy subjects, high SMRP levels were associated with the C-variant of New1, with an average 1.62-fold increase compared with AA homozygotes (p<0.0001). Most of the C-allele carriers had SMRP levels above the threshold of 1.00 nM. We set two different SMRP cutoffs on the basis of the combined New1+New2 genotypes.? New1-New2 genotypes could be employed as markers for setting individualized and appropriate thresholds of "normality" when SMRP is used in surveillance programs of asbestos-exposed people.

Association of MiR-126 with Soluble Mesothelin-Related Peptides, a Marker for Malignant Mesothelioma

BackgroundImproved detection methods for diagnosis of malignant pleural mesothelioma (MPM) are essential for early and reliable detection as well as treatment. Since recent data point to abnormal levels of microRNAs (miRNAs) in tumors, we hypothesized that a profile of deregulated miRNAs may be a marker of MPM and that the levels of specific miRNAs may be used for monitoring its progress.Methods and ResultsmiRNAs isolated from fresh-frozen biopsies of MPM patients were tested for the expression of 88 types of miRNA involved in cancerogenesis. Most of the tested miRNAs were downregulated in the malignant tissues compared with the normal tissues. Of eight significantly downregulated, three miRNAs were assayed in cancerous tissue and adjacent non-cancerous tissue sample pairs collected from 27 formalin-fixed, paraffin-embedded MPM tissues by quantitative RT-PCR. Among the miRNAs tested, only miR-126 significantly remained downregulated in the malignant tissues. Furthermore, the performance of the selected miR-126 as biomarker was evaluated in serum samples of asbestos-exposed subjects and MPM patients and compared with controls. MiR-126 was not affected by asbestos exposure, whereas it was found strongly associated with VEGF serum levels. Levels of miR-126 in serum, and its levels in patients' serum in association with a specific marker of MPM, SMRPs, correlate with subjects at high risk to develop MPM.Conclusions and SignificanceWe propose miR-126, in association with SMRPs, as a marker for early detection of MPM. The identification of tumor biomarkers used alone or, in particular, in combination could greatly facilitate the surveillance procedure for cohorts of subjects exposed to asbestos.

Exposure to asbestos: Correlation between blood levels of mesothelin and frequency of micronuclei in peripheral blood lymphocytes

Inhalation of asbestos, a mineral extensively used in a variety of applications, is strongly associated with malignant mesothelioma (MM), a fatal cancer of the pleura. Soluble mesothelin-related peptides (SMRP) are a promising biomarker suggested for the screening of MM in healthy asbestos-exposed subjects. In the present study a comparison of micronucleus (Mn) frequencies in peripheral blood lymphocytes (PBL) between 44 asbestos-exposed and 22 control individuals has been performed, and the correlation with serum SMRP has been examined. SMRP levels were found to be significantly higher in subjects exposed to asbestos and in their various subgroups than in controls. Concerning micronucleated lymphocytes, a statistically significant difference from controls was seen in the percentages of both micronucleated mononucleated lymphocytes (MnMNL) and micronucleated binucleated lymphocytes (MnBNL), but the difference was markedly higher for the percentage of micronucleated polynucleated lymphocytes (MnPNL). With respect to the correlation between the frequency of the three types of micronucleated lymphocytes and serum-SMRP values of asbestos-exposed subjects, it was statistically significant for MnMNL, but not for MnBNL and MnPNL.

Exploratory Study on the Detection of Markers for Diagnosing Early-Stage Malignant Mesothelioma

Malignant mesothelioma (MM) is a highly aggressive, incurable neoplasm associated with asbestos exposure. Early detection of MM is not easy and radiological surveillance is imperfect. The use of blood-based biomarkers might solve this difficulty and allow detection of MM at an early stage when combined treatment involving surgery, chemotherapy and radiotherapy might be effective. In the research project entitled "Comprehensive approach on asbestos-related diseases" supported by the "Special Coordination Funds for Promoting Science and Technology (H18-1-3-3-1)", we conducted an exploratory study on the detection of markers for diagnosing early-stage MM. In this study, we have shown that serum soluble mesothelin-related peptide (SMRP) is a highly specific and moderately sensitive biomarker for diagnosing MM. SMRP levels in pleural effusion were elevated not only in advanced-stage malignant pleural mesothelioma (MPM), but also in early-stage disease. SMRP in pleural effusion can be an MPM-specific biomarker with greater sensitivity than in serum, especially for the early stage of the disease. Circulating tumor cells (CTCs) and circulating endothelial cells (CECs) were considered to be useful surrogate markers of disease progression in MPM, although the lack of sensitivity for early-stage disease remains to be improved. Cytological analysis with gene expression profiling has been more effective in detecting early-stage MPM with pleural effusion. In conclusion, blood or effusion-based biomarkers, possibly in combination with other new modalities, such as a thoracoscopy combined with the advanced imaging systems consisting of autofluorescence imaging (AFI) and narrow band imaging (NBI), will show some promise for curing MPM if the disease is detected at an early stage.

Performance of biomarkers SMRP, CA125, and CYFRA 21-1 as potential tumor markers for malignant mesothelioma and lung cancer in a cohort of workers formerly exposed to asbestos

The aim of the study is to examine the cancer-predictive values of SMRP (soluble mesothelin-related peptides), CA125, and CYFRA21-1 as potential tumor markers for lung cancer and malignant mesothelioma in a cohort of workers formerly exposed to asbestos. A voluntary surveillance program has been established for German workers with former asbestos exposure. A subgroup of 626 subjects with a mean age of 63 years (range 53-70 years) at baseline was enrolled in an extended health examination program with high-resolution computer tomography (HRCT) of the chest and blood drawing between 1993 and 1997. Serum concentrations of SMRP, CA125, and CYFRA21-1 were measured in archived serum samples in 2005 and 2006. A mortality follow-up was conducted through 2007. So far, 12 cases with lung cancer and 20 cases with malignant mesothelioma have been observed in this cohort. The average time between sample collection and diagnosis was 4.7 years. Analyzed biomarkers showed low sensitivities (5-25%) and positive predictive values (4-30%) for both cancer sites. Marker combinations resulted in sensitivities between 5 and 50% and positive predictive values ranging from 3 to 14%. Even in those cases, where biomarker concentrations were available within 36 months before diagnosis, no trend for increasing biomarker levels was observed. The analyzed tumor markers were characterized by high specificities, but low sensitivities. SMRP, CA125, and CYFRA21-1 alone or in combination were less suitable to serve as predictors for the diagnosis of lung cancer or malignant mesothelioma. However, a prospective study with annual sampling might reveal a better predictive value of these markers.

Soluble Mesothelin-Related Peptide and Osteopontin As Markers of Response in Malignant Mesothelioma

In malignant mesothelioma (MM), radiologic assessment of disease status is difficult. Both soluble mesothelin-related peptide (SMRP) and osteopontin (OP) have utility in distinguishing MM from benign pleural disease. We evaluated whether SMRP and OP also correlated with the disease course of MM. Serial plasma samples from patients with MM were prospectively collected, and SMRP and OP levels were measured. Radiologic tests across time periods showing disease progression, stability, or shrinkage were compared with corresponding changes in SMRP/OP levels. From 41 patients, 165 samples were collected (range, 2 to 10; median 4). At study entry, 37 of 41 patients had measurable disease, of whom 92% (34 of 37) had elevated baseline SMRP levels; four of 41 patients had no evidence of recurrence and each had normal baseline SMRP levels. In 21 patients receiving systemic therapy, percentage change in SMRP more than 10% correlated with the radiologic assessment by a trained thoracic radiologist (P < .001), by formal Response Evaluation Criteria in Solid Tumors (RECIST; P = .008), or by modified RECIST (P < .001). All seven patients who underwent surgical resection with negative margins had elevated preoperative SMRP levels that fell to normal postoperatively. Rising SMRP was observed in all patients with radiologic disease progression. No associations were found with OP. Percentage changes in SMRP levels, but not changes in OP levels, are a potentially useful marker of disease course. These findings should be validated prospectively for a role as an objective adjunctive measure of disease course in both clinical trials and clinical practice.

Abstract 3229: Biomarker validation for a rare malignancy in a mouse model

Abstract Purpose: Malignant pleural mesothelioma (MPM) is a rare malignancy often diagnosed at an advanced stage. Clinical validation of a biomarker that would allow for earlier diagnosis as well as detection of recurrence following therapy is limited by the rarity of the tumor. Soluble mesothelin-related peptide (SMRP), which can be detected in patients’ serum, is a cleavage product of mesothelin, a tumor-associated cell surface protein over-expressed in &amp;gt;80% of MPMs. The purpose of this study is to validate the pharmacodynamics of SMRP as a tumor biomarker of prognosis and therapy response using a clinically and pathologically relevant orthotopic xenograft model of MPM. Experimental Design: Orthotopic MPM xenograft mice (athymic nude and SCID-beige) were established by direct pleural injection of human mesothelioma cells (MSTO-211H) retrovirally transduced to stably express mesothelin and the GFP-Firefly Luciferase fusion gene. Quantitative bioluminescence imaging (BLI) and MRI were used to serially monitor tumor burden and progression and were correlated with serum SMRP levels (Mesomark® ELISA assay). Kaplan-Meier survival analyses were performed following xenografting of mesothelin and non-mesothelin expressing tumors. The utility of SMRP as a biomarker of therapeutic response was validated by treating MPM mice with either: (a) Cisplatin (4mg/kg IP weekly), (b) thoracic radiation (20Gy total in 5 fractions), (c) combination chemoradiation, or (d) no treatment and correlating serial SMRP levels to survival and BLI signal. Results: MPM cells secreting SMRP demonstrated increased invasion and migration in vitro as assessed by the modified Boyden Chamber assay compared to cells without SMRP secretion, 124 vs 48 cells per high-powered field (p&amp;lt;0.0001) and 49 vs 32 cells (p=0.017), respectively. In MPM xenograft mice, increasing SMRP levels correlated with tumor progression by quantitative BLI (spearman r=0.89, p=0.04) and decreased survival (p=0.001). SMRP demonstrated improved sensitivity for detecting early MPM tumors compared to MRI. SMRP levels significantly decreased following treatment versus control mice (p=0.03) and were predictive of survival (hazard ratio = 4.5, 95%CI 1.53-13.1). In addition, SMRP detected tumor recurrence following treatment earlier than MRI. Conclusions: We have shown that a serum biomarker of tumor progression and therapy response can be successfully studied in a clinically relevant animal model. To our knowledge, this is the first report utilizing BLI as a reproducible tool, in conjunction with an orthotopic animal model, to quantitatively assess pleural tumor burden and biomarker pharmacodynamics. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3229.

Soluble mesothelin related peptides (SMRP) and osteopontin as protein biomarkers for malignant mesothelioma: analytical validation of ELISA based assays and characterization at mRNA and protein levels

There is a need to identify reliable markers for malignant mesothelioma. Soluble mesothelin related peptides (SMRP) and osteopontin (OPN) have gained interest in recent years for this purpose. SMRP (Fujirebio Diagnostics Inc.) and OPN (R&D Inc.) ELISA methods were evaluated for multiple parameters. Concentrations were measured in blood from patients with mesothelioma, normal healthy volunteers, and patients with other (non-mesothelioma) cancers. In silico analysis was performed using the GeoProfiles database. At the protein level, SMRP and OPN were measured in cell culture supernatants, and values were compared in patients pre- and post-extrapleural pneumonectomy. The SMRP assay demonstrates intra-assay CVs of 2.3% and 3% (at 4.6 nM and 13.7 nM, respectively), and inter-assay CVs of 3.5% and 3.7% at the same concentrations. The limit of detection (LOD) is 0.182 nM. The OPN assay demonstrates intra-assay CVs of 5.8%, 4.1%, and 5.2% (at 1.9, 5.1, and 11.1 ng/mL, respectively), and inter-assay CVs of 8.5%, 8.4%, and 12.1% at the same concentrations. The LOD is 0.032 ng/mL. Both SMRP and OPN in mesothelioma patients were significantly higher than in patients with other (non-mesothelioma) cancer and in healthy volunteers. The two markers do not appear to correlate with each other and exhibit different tissue expression patterns. Protein concentrations of these markers are highest in different sets of cell lines. Finally, SMRP but not OPN concentrations were decreased in five of seven consecutive patients after extrapleural pneumonectomy, compared to their respective pre-operative values. These assays provide reliable and reproducible quantitation of SMRP and OPN proteins. Both are increased in mesothelioma patients compared to non-mesothelioma controls. However, the two analytes do not correlate with each other and show distinct expression profiles and protein expression. Concentrations of SMRP but not OPN are decreased in post-surgical samples. Our results further characterize these markers, establish assay performance characteristics, and lay the groundwork for further studies to measure these markers in blood.

Abstract B27: A preclinical mouse model of orthotopic pleural cancer that facilitates noninvasive quantitative monitoring of tumor progression and therapy response

Abstract Purpose: The purpose of our study is to (a) establish a reproducible mouse model of orthotopic pleural cancer that recapitulates the pathobiology of human pleural malignancy (including primary malignant pleural mesothelioma, lung and metastatic breast cancers), and (b) validate the use of bioluminescence imaging (BLI) and serum biomarker assessment to noninvasively monitor tumor progression and therapy response in preclinical therapeutic trials. Experimental Design and Results: Human mesothelioma and lung cancer cell lines with variable expression levels of the tumor-associated antigen, mesothelin, were retrovirally transduced to stably express GFP-Firefly Luciferase, to facilitate BLI. Orthotopic xenograft mice were established by direct tumor cell inoculation into the pleural space with &amp;gt; 95% engraftment in both athymic nude and SCID-beige mice. The pathobiologic resemblance of the xenograft tumors to human disease was confirmed by demonstrating: (a) visceral and parietal pleural tumor growth 58 pattern, mediastinal lymph node involvement, and diaphragmatic invasion by magnetic resonance imaging (MRI) and histology, (b) strong, sustained expression of tumor markers at advanced stage of disease by WT-1, Calretinin, Mesothelin, and TTF-1 immunohistochemistry, and (c) extensive tumor lymphangiogenesis by CD-34 and LYVE-1 immunofluorescence. Tumor burden correlated with BLI signal (total flux photons/s) and soluble mesothelin-related peptide, SMRP (Mesomark® ELISA assay) both in vitro and in vivo (Pearson's correlation r=0.998, p&amp;lt;0.0001 and r=0.89, p=0.04, respectively). We determined the accuracy of BLI and SMRP (range 0.4–23nM) in monitoring tumor progression by serial assessment of xenograft mice (n=36, with initial tumor burden of 1×103–1×106 cells). In the orthotopic pleural xenografts, BLI signal correlated with SMRP (r=0.56, p=0.0001); no such correlation was observed in subcutaneous flank or intraperitoneal xenografts. To further demonstrate the reliability of BLI and SMRP to noninvasively monitor therapeutic response, groups of pleural mesothelioma xenografts (n=28) were treated with either: (a) Cisplatin (4mg/kg IP weekly), (b) thoracic radiation (20Gy total in 5 fractions), (c) combination chemoradiation, or (d) no treatment. BLI, SMRP, and survival were followed serially. Therapy response was demonstrated by decreased BLI intensity in mice treated with chemoradiation compared to controls (3.7×107 vs 2.0×108 photons/s, respectively, p=0.04) as well as decreased SMRP (p=0.03) which correlated with improved survival by Kaplan-Meier analysis (64 vs 34.5 days, p=0.0001). Conclusions: Pleural involvement by solid tumors remains a significant problem in clinical oncology affecting nearly 250,000 patients annually in the U.S. with no validated preclinical model for therapeutic investigations. We have validated a clinically relevant, reproducible orthotopic model of pleural malignancy that recapitulates human disease and allows for noninvasive quantitative monitoring of pleural tumor burden, progression and therapeutic response. Our xenograft model provides a novel platform to investigate targeted therapies for pleural malignancies. Citation Information: Cancer Res 2009;69(23 Suppl):B27.

Diagnostic value of soluble mesothelin-related peptides for malignant mesothelioma: A meta-analysis

Serum concentrations of soluble mesothelin-related peptides (SMRP) have been reported to be higher in patients with malignant mesothelioma than in healthy subjects and in patients with non-malignant mesothelioma diseases. The aim of the present meta-analysis was to establish the overall diagnostic accuracy of the measurement of SMRPs for diagnosing malignant mesothelioma. After a systematic review of English language studies, sensitivity, specificity, and other measures of accuracy of serum SMRPs in the diagnosis of malignant mesothelioma were pooled using random-effects models. Summary receiver operating characteristic curves were used to summarize overall test performance. Eleven publications from 12 studies met our inclusion criteria. The summary estimates for SMRPs in the diagnosis of malignant mesothelioma in the studies included were sensitivity 0.64 (95% confidence interval 0.61-0.68), specificity 0.89 (0.88-0.90), positive likelihood ratio 7.10 (4.44-11.35), negative likelihood ratio 0.39 (0.31-0.48), and diagnostic odds ratio 19.35 (10.95-34.17). Serum SMRP determination plays a role in the diagnosis of malignant mesothelioma. The results of SMRP assays should be interpreted in parallel with clinical findings and the results of conventional tests.

Pleural fluid mesothelin for the differential diagnosis of exudative pleural effusions

Malignant mesothelioma (MM) is a highly aggressive tumor that can be difficult to diagnose, resulting in a delayed diagnosis in some cases. Recent studies have reported that determination of soluble mesothelin-related peptides (SMRP) in pleural fluid may be a promising marker for use in the diagnosis of MM. Pleural fluid SMRP concentration was measured in 68 patients: 47 had malignant pleural effusions (18 MM and 29 metastatic effusion) and 21 had benign pleural effusion (8 infectious disease and 13 idiopathic effusion). Mann-Whitney analysis was used to compare SMRP values according to the etiology of the effusion. Pleural fluid SMRP concentration was significantly higher in patients with malignant pleural effusion than in those with benign effusion (P=0.02). When malignant pleural effusions were analyzed separately, MM patients had the highest median pleural fluid SMRP concentration, with significant differences as compared to patients with idiopathic pleural effusion. Soluble mesothelin-related peptide measurement in pleural fluid may aid in the diagnosis of patients presenting with pleural effusion.

Malignant Pleural Mesothelioma: An Update on Biomarkers and Treatment

Although the insulating properties of asbestos have been known for millennia, the link between asbestos exposure and mesothelioma was not recognized until 1960, when it was first described in South African asbestos miners. The incidence of mesothelioma parallels asbestos usage with a latency of 20 to 40+ years; thus, patient numbers are declining in the United States but rising in the developing world. Radiation, genetics, and possibly simian virus 40 are less common causes. Diagnosis can be challenging, since the results of pleural fluid cytology testing are often negative despite repeated sampling. No staging system adequately predicts prognosis in the unresected patient. Newly described biomarkers, including soluble mesothelin-related peptide, megakaryocyte potentiation factor, and osteopontin, may predict which asbestos-exposed individuals will develop mesothelioma, and may prove useful in assessing response to treatment. Since surgery cannot eradicate all residual microscopic disease, a multimodality approach is encouraged. Metaanalysis suggests that pleurectomy/decortication may achieve outcomes similar to those of extrapleural penumonectomy. The standard first-line chemotherapy for unresectable disease is pemetrexed plus cisplatin. This combination improves response, survival, time to progression, pulmonary function, and disease-related symptoms. Carboplatin is often substituted, with similar results. Other active agents include raltitrexed, gemcitabine, and vinorelbine. Novel agents in clinical trials include inhibitors of the epidermal growth factor receptor, vascular endothelial growth factor, mesothelin, and histone deacetylases. Although disappointing results of early trials did not confirm promising preclinical data, recent studies have suggested that some novel agents may be effective. As we learn more about mesothelioma biology, molecularly targeted agents may become treatment options.

Mesothelin as a marker of response in malignant pleural mesothelioma

7581 Background: Malignant pleural mesothelioma (MPM) is a rare malignancy related to asbestos exposure. Radiological assessment of disease status and treatment response using RECIST criteria is often difficult, therefore blood markers of disease burden may be useful adjunctively. Soluble mesothelin related peptide (sMRP) can distinguish between MPM and benign pleural disease. We performed an exploratory analysis to determine whether sMRP correlates with MPM disease course. Methods: From December 2006 to August 2008 blood samples were collected from MPM patients during clinic visits. Plasma sMRP levels were measured using the MESOMARK assay (Fujirebio diagnostics). Changes in sMRP levels were compared with corresponding radiological tests, scored as progression, stable or disease shrinkage. Results: From 41 patients, 165 samples were collected (median 4/patient; range 2–10). At study entry 34/37 (92%) patients with measurable disease had elevated sMRP (&gt;9ng/ml, range 14–60). In 22 patients receiving chemotherapy or biologic therapy, relative (Fisher's exact test, p=3.2x10–6) and absolute (p=2.6x10–5) changes in sMRP correlated with radiological assessment (Table). All 4 post-surgery surveillance patients, with no evidence of recurrence, had normal sMRP levels (1.8–4.9). Of 8 patients who underwent surgical resection, 7 had elevated pre-operative sMRP that fell to normal post-operatively (Wilcoxon rank (WR) p=0.02). Absolute sMRP rose in all patients with radiological progression (systemic therapy, n=9, WR p=0.004; supportive care, n=10, WR p=0.02). Conclusions: sMRP levels not only correlate with surgical debulking but we report, for the first time, that they also correlate with treatment response and radiological progression in MPM patients undergoing systemic therapy or supportive care. sMRP may be a clinically useful biomarker in MPM clinical trials and in patient management. These findings should be validated prospectively. [Table: see text] [Table: see text]

Serum Levels of Soluble Mesothelin-Related Peptides in Malignant and Nonmalignant Asbestos-Related Pleural Disease: Relation with Past Asbestos Exposure

Malignant pleural mesothelioma (MPM) results from malignant transformation of mesothelial cells. Past asbestos exposure represents a major risk factor for MPM and other benign pleural disease. Soluble mesothelin-related peptides (SMRP) have been regarded as a promising serum biomarker for MPM. The aim of this study was to investigate serum levels of SMRP in malignant and nonmalignant asbestos-related pleural disease. Four groups of patients were investigated: group 1 composed of 48 healthy subjects, group 2 composed of 177 patients with previous asbestos exposure and no pleural disease, group 3 composed of 36 patients with MPM, and group 4 composed of 101 patients with previous asbestos exposure and benign pleural disease. Serum SMRP levels were determined by ELISA. Serum SMRP levels were significantly higher among group 3 than the other three groups. There were no differences in SMRP concentrations between groups 2 and 4. Subjects exposed to asbestos had higher SMRP concentrations than normal control subjects regardless of the presence of pleural disease. The area under the receiver operating characteristic curve for SMRP values was 0.75 (95% confidence interval, 0.68-0.83). The SMRP level at 0.55 nmol/L/L was determined as the most optimal cutoff value with resulting sensitivity and specificity of 72% and 72% for the diagnosis of MPM. These data attest to good diagnostic sensitivity and specificity of SMRP for the diagnosis of malignant mesothelioma. We have also shown that serum SMRP levels might serve as a marker of asbestos exposure.

可溶型メソテリン関連蛋白（SMRP: Soluble Mesothelin-related Peptides）の悪性胸膜中皮腫におけるバイオマーカーとしての意義

悪性胸膜中皮腫はアスベスト曝露に起因する難治性悪性腫瘍であり,我が国においては2030年まで増加し続けることが予測されている.これまで,悪性胸膜中皮腫のバイオマーカーについての検討は少なく,補助診断あるいは治療効果や予後予測に際して有用かつ信頼できるバイオマーカーはなかった.今回,我々は,悪性胸膜中皮腫診断における可溶型メソテリン関連蛋白(SMRP: soluble mesothelin-related peptides)のバイオマーカーとしての意義を前向きの多施設共同研究で検討した.本稿では,悪性胸膜中皮腫に関する知見,治療法,および診断のためのバイオマーカーについて特に重要な論文を中心にレビューし,さらに,我々が行った前向きの多施設共同研究の結果の一部を報告する.

Assessment of Biomarkers in asbestos-exposed workers as indicators of cancer risk

Epidemiological studies have shown that mortality from malignant mesothelioma (MM) and lung cancer have increased with increasing cumulative exposure to asbestos. To investigate whether tumour-related biomarkers can contribute towards the evaluation of the carcinogenic risk in populations exposed to asbestos, the DNA adduct 8-hydroxy-2′-deoxyguanosine (8OHdG), interleukine-6 (IL-6), platelet-derived growth factor (PDGF-BB), hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGFβ) and soluble mesothelin-related peptides (SMRPs) were analysed in a cohort of workers differently exposed to asbestos fibres at the workplace. To document biomarker levels in an unexposed population, 54 age-matched subjects were enrolled. A total of 119 subjects with a history of occupational exposure to asbestos underwent clinical examination and were interviewed by trained personnel, responding to a detailed questionnaire related to duration of asbestos exposure, smoking, and occupational task. According to the occupational tasks, asbestos-exposed subjects were analysed for their asbestos cumulative dose and the association with the biomarkers was evaluated. Among the occupational groups, maintenance workers, pipe fitters and electricians were exposed to a higher cumulative dose of asbestos fibres. Exposure to asbestos significantly increased the steady-state content of 8OHdG in DNA. Elevated levels of 8OHdG and IL-6 best reflected a high level of SMRPs, which is related to cell transformation. Subjects heavily exposed to asbestos [>60 (ff/cm 3) × years] showed also a higher level of angiogenic factors. A combination of angiogenic biomarkers with a specific mesothelioma-biomarker such as SMRPs could be used for close surveillance of workers with a history of asbestos exposure.

Serum and intracavitary soluble mesothelin-related peptide (SMRP) levels in pleural and peritoneal malignant mesothelioma

22103 Background: Mesothelin is a 40kDa cell surface protein known to be overexpressed in mesothelioma. Soluble mesothelin related protein (SMRP) is theorized to be a useful blood test marker of mesothelioma tumor load. We examined whether serum SMRP is related to site (pleural or peritoneal), histological subtype (epithelioid, sarcomatous, biphasic), or CRP levels, and whether SMRP is detectable in cavitary effusions. Methods: Serum SMRP and CRP were measured on 1 or more occasions from May to December 2007 in 69 patients with malignant mesothelioma of the pleura (n = 20), peritoneum (n = 43), or both (n = 6); of epithelioid (n = 58), sarcomatoid (n = 5), or biphasic (n = 6) histology. Pleural effusion or peritoneal fluid SMRP was measured in 12 of these patients. These were grouped by site and histology and compared by 2-tailed Welch t-test, with levels below limit of detection (0.3 nM) recorded as 0. Results: Serum SMRP were higher in pleural (6.2 ± 1.1 nM) than peritoneal (4.3 ± 1.1 nM) patients (p = 0.015). 42% of pleural patients had an average serum SMRP within normal limits (<1.5 nM), vs 57% of peritoneal patients. Differences between epithelioid (4.5 ± 0.8 nM) and the small subset of sarcomatoid/biphasic (5.7 ± 3.8 nM) patients were not statistically significant (p = 0.574). Cavitary SMRP was higher than serum in all 3 pleural patients and in 5 of 9 peritoneal patients. Serial samples from individual treated patients, often but not always paralleled increased or decreased tumor burden after surgery or chemotherapy. No correlation was found between SMRP and CRP in any group. Conclusions: Changes in SMRP levels in individual patients, especially with pleural disease, can reflect tumor burden after operation or chemotherapy, and might be explored as a means of detecting residual or progressive disease in pleural effusions. The relationship between cavitary and serum SMRP is less predictable in abdominal ascites than in pleural effusions. SMRP elevations are distinct from elevated CRP, and may reflect different processes. No significant financial relationships to disclose.

Profiling Tumor-Associated Markers for Early Detection of Malignant Mesothelioma: An Epidemiologic Study

Improved detection methods for diagnosis of asymptomatic malignant mesothelioma (MM) are essential for an early and reliable detection and treatment of this type of neoplastic disease. Thus, focus has been on finding tumor markers in the blood that can be used for noninvasive detection of MM. Ninety-four asbestos-exposed subjects defined at high risk, 22 patients with MM, and 54 healthy subjects were recruited for evaluation of the clinical significance of 8-hydroxy-2'-deoxyguanosine (8OHdG) in WBCs and plasma concentrations of soluble mesothelin-related peptides (SMRPs), angiogenic factors [platelet-derived growth factor beta, hepatocyte growth factor, basic fibroblast growth factor, and vascular endothelial growth factor beta (VEGFbeta)], and matrix proteases [matrix metalloproteinase (MMP) 2, MMP9, tissue inhibitor of metalloproteinase (TIMP) 1, and TIMP2] for potential early detection of MM. The area under receiver operating characteristic (ROC) curves indicate that 8OHdG levels can discriminate asbestos-exposed subjects from healthy controls but not from MM patients. Significant area under ROC curve values were found for SMRPs, discriminating asbestos-exposed subjects from MM patients but not from healthy controls. Except for platelet-derived growth factor beta, the hepatocyte growth factor, basic fibroblast growth factor, and VEGFbeta can significantly differentiate high-risk individuals from healthy control and cancer groups. No diagnostic value was observed for MMP2, MMP9, TIMP1, and TIMP2. In addition to the diagnostic performance defined by the ROC analysis, the sensitivity and specificity results of markers with clinical significance were calculated at defined cutoffs. The combination of 8OHdG, VEGFbeta, and SMRPs best distinguished the individual groups, suggesting a potential indicator of early and advanced MM cancers. The combination of blood biomarkers and radiographic findings could be used to stratify the risk of mesothelioma in asbestos-exposed populations.

Soluble Mesothelin-Related Peptide Level Elevation in Mesothelioma Serum and Pleural Effusions

Soluble mesothelin-related peptide (SMRP) is a potential marker for malignant pleural mesothelioma (MPM), which may be useful for screening high-risk asbestos-exposed individuals. We evaluated SMRP in serum from MPM patients (n = 90), lung cancer patients (n = 170), age and tobacco-matched asbestos-exposed individuals (n = 66), and in MPM pleural effusions (n = 45), benign effusions (n = 30), and non-MPM effusions (n = 20) using the MesoMark enzyme-linked immunosorbent assay kit (Fujirebio Diagnostics, Malvern, PA). Receiver operating characteristic (ROC) curves were used to define true and false positive rates at various cutoffs. Mean serum SMRP levels were higher in MPM compared with lung cancer (5.67 +/- 0.82 nM [mean +/- standard error of the mean vs 1.99 +/- 0.43 nM, p < 0.001), and stage I MPM SMRP levels (n = 12; 2.09 +/- 0.41 nM) were significantly higher than those in asbestos-exposed individuals (0.99 +/- 0.09 nM, p = 0.02, respectively). Stage 2 to 4 SMRP serum levels were significantly higher than those for stage 1 MPM. The area under the ROC curve for serum SMRP was 0.81 for differentiating MPM and asbestos-exposed individuals; cutoff = 1.9 nM (sensitivity = 60%, specificity = 89%). The MPM pleural effusion SMRP was significantly higher than benign or other non-MPM pleural effusions (65.57 +/- 11.33 nM vs 27.46 +/- 11.25 nM [p = 0.003] and 18.99 +/- 7.48 nM [p = 0.044], respectively). These data support SMRP as a promising marker for MPM in both serum and pleural effusion fluid, and justify prospective screening studies of SMRP in combination with other markers for screening of asbestos-exposed cohorts.

Soluble mesothelin-related peptides (SMRP) – High stability of a potential tumor marker for mesothelioma

SMRP (soluble mesothelin-related peptides) is a promising marker for detection of malignant mesotheliomas (MM) in serum that has not yet been validated in appropriate epidemiological studies. Field studies might not always provide optimal conditions for storage and transport of samples, and follow-up studies have to rely on sample integrity. Proper validation of the marker would require sufficient stability of the antigen and robustness of the assay. SMRP concentrations were evaluated in serum samples of 98 healthy donors, using the MESOMARK ELISA kit. The SMRP distribution in the healthy study population was determined and biological and pre-analytical variations were examined regarding their influence on SMRP concentrations. For diagnostic decisions a best statistical and unbiased cut-off between 1.5 and 1.6 nmol/L was determined (95th percentile). No age- or gender-specific differences could be observed. SMRP exhibits excellent stability regarding short-term storage, long-term storage, and repeated freeze/thaw cycles. Scientific studies as well as real life applications that employ SMRP would not be limited by sample stability issues.