Lung cancer and mesothelioma risks in a prospective cohort of workers with asbestos-related lung or pleural diseases.

BACKGROUND: Asbestos causes mesothelioma and lung cancer. In the European Union, asbestos was banned in 2005, but it is still in use in many other countries. The aim of this study was to estimate the lung cancer and mesothelioma incidence risk of men with benign asbestos-related lung or pleural diseases. METHODS: Between 2008 and 2018, 2439 male participants of a German surveillance program for asbestos workers were included in the cohort. All participants had a recognized occupational asbestos-related disease of the pleura or lung. We estimated the mesothelioma and lung cancer risks by calculating standardized incidence ratios (SIR) with corresponding 95% confidence intervals (95% CI). RESULTS: We observed 64 incident lung cancer and 40 mesothelioma cases in the cohort. An SIR of 17.60 (95% CI: 12.57-23.96) was estimated for mesothelioma and 1.27 (95% CI: 0.98-1.62) for lung cancer. The presence of pleural plaques was associated with a strongly increased risk (SIR: 13.14; 95% CI: 8.51-19.40) for mesothelioma, but not for lung cancer (SIR: 1.05; 95% CI: 0.76-1.41). The highest lung-cancer risk (SIR: 2.56; 95% CI 1.10-5.04) was revealed for cohort members with less than 40 years since first asbestos exposure. Lung cancer risks by duration of asbestos exposure did not show a consistent time trend, but for time since last exposure a trend for mesothelioma was seen. CONCLUSIONS: Compared to the general population, we demonstrated an association between benign asbestos-related lung or pleural disease and mesothelioma risk in workers with a history of occupational asbestos exposure. Because lung-cancer risk is dominated by smoking habits, a possible effect of asbestos exposure may have been masked. Efforts should be made to ban production and use of asbestos worldwide and to establish safe handling rules of legacy asbestos.

Calretinin as a blood-based biomarker for mesothelioma.

BACKGROUND: Malignant mesothelioma (MM) is a deadly cancer mainly caused by previous exposure to asbestos. With a latency period up to 50 years the incidence of MM is still increasing, even in countries that banned asbestos. Secondary prevention has been established to provide persons at risk regular health examinations. An earlier detection with tumor markers might improve therapeutic options. Previously, we have developed a new blood-based assay for the protein marker calretinin. Aim of this study was the verification of the assay in an independent study population and comparison with the established marker mesothelin. METHODS: For a case-control study in men, a total of 163 cases of pleural MM and 163 controls were available from Australia, another 36 cases and 72 controls were recruited in Germany. All controls had asbestosis and/or plaques. Calretinin and mesothelin were determined by ELISA (enzyme-linked immunosorbent assay) in serum or plasma collected prior to therapy. We estimated the performance of both markers and tested factors potentially influencing marker concentrations like age, sample storage time, and MM subtype. RESULTS: Calretinin was able to detect all major subtypes except for sarcomatoid MM. Calretinin showed a similar performance in Australian and German men. At a pre-defined specificity of 95% the sensitivity of calretinin reached 71% and that of mesothelin 69%, when excluding sarcomatoid MM. At 97% specificity, the combination with calretinin increased the sensitivity of mesothelin from 66% to 75%. Sample storage time did not influence the results. In controls the concentrations of calretinin increased 1.87-fold (95% CI 1.10-3.20) per 10 years of age and slightly more for mesothelin (2.28, 95% CI 1.30-4.00). CONCLUSIONS: Calretinin could be verified as a blood-based marker for MM. The assay is robust and shows a performance that is comparable to that of mesothelin. Retrospective analyses would not be limited by storage time. The high specificity supports a combination of calretinin with other markers. Calretinin is specific for epithelioid and biphasic MM but not the rarer sarcomatoid form. Molecular markers like calretinin and mesothelin are promising tools to improve and supplement the diagnosis of MM and warrant further validation in a prospective study.

Combination of calretinin, MALAT1, and GAS5 as a potential prognostic biomarker to predict disease progression in surgically treated mesothelioma patients.

BACKGROUND: The role of cytoreductive surgery for epithelioid pleural mesothelioma within a multimodal treatment approach remains controversial. Carefully selected patients benefit from cytoreductive surgery and adjuvant chemotherapy, but there is no established biomarker to predict tumor recurrence or progression during the course of the disease. The aim of this study was to identify potential biomarkers to predict therapeutic response in terms of progression-free survival. METHODS: Between 03/2014 and 08/2022, preoperative blood samples were collected from 76 patients with epithelioid pleural mesothelioma who underwent cytoreductive surgery as part of a multimodal treatment approach. Identification of potential biomarkers was performed by determination of mesothelin and calretinin, as well as specific long non-coding RNAs and microRNAs. Receiver operating characteristic analysis, Kaplan-Meier survival analysis, and Cox regression were used to assess the association between biomarker concentrations and patient recurrence status and survival. RESULTS: MALAT1, GAS5, and calretinin showed statistically significant increased biomarker levels in patients with recurrence in contrast to recurrence-free patients after surgical treatment (p < 0.0001, p = 0.0190, and p = 0.0068, respectively). The combination of the three biomarkers resulted in a sensitivity of 68 % and a specificity of 89 %. CONCLUSION: MALAT1, GAS5, and calretinin could be potential biomarkers for the prediction of tumor recurrence, improving the benefit from multimodal treatment including cytoreductive surgery.

Assessment of MYC and TERT copy number variations in lung cancer using digital PCR.

OBJECTIVE: Lung cancer is the second most frequent cancer type and the most common cause of cancer-related deaths worldwide. Alteration of gene copy numbers are associated with lung cancer and the determination of copy number variations (CNV) is appropriate for the discrimination between tumor and non-tumor tissue in lung cancer. As telomerase reverse transcriptase (TERT) and v-myc avian myelocytomatosis viral oncogene homolog (MYC) play a role in lung cancer the aims of this study were the verification of our recent results analyzing MYC CNV in tumor and non-tumor tissue of lung cancer patients using an independent study group and the assessment of TERT CNV as an additional marker. RESULTS: TERT and MYC status was analyzed using digital PCR (dPCR) in tumor and adjacent non-tumor tissue samples of 114 lung cancer patients. The difference between tumor and non-tumor samples were statistically significant (p < 0.0001) for TERT and MYC. Using a predefined specificity of 99% a sensitivity of 41% and 51% was observed for TERT and MYC, respectively. For the combination of TERT and MYC the overall sensitivity increased to 60% at 99% specificity. We demonstrated that a combination of markers increases the performance in comparison to individual markers. Additionally, the determination of CNV using dPCR might be an appropriate tool in precision medicine.

Development of an enzyme-linked immunosorbent assay for the detection of human calretinin in plasma and serum of mesothelioma patients.

BACKGROUND: Calretinin is one of the well-established immunohistochemical markers in the diagnostics of malignant mesothelioma (MM). Its utility as a diagnostic tool in human blood, however, is scarcely investigated. The aim of this study was to develop an enzyme-linked immunosorbent assay (ELISA) for human calretinin in blood and to assess its usefulness as a potential minimally invasive diagnostic marker for MM. METHODS: Initially, attempts were made to establish an assay using commercially available antibodies and to optimize it by including a biotin-streptavidin complex into the assay protocol. Subsequently, a novel ELISA based on polyclonal antibodies raised in rabbit immunized with human recombinant calretinin was developed. The assay performance in human serum and plasma (EDTA/heparin) and the influence of calcium concentrations on antibody recognition were studied. Stability of spiked-in calretinin in EDTA plasma under different storage conditions was also examined. In preliminary studies serum and plasma samples from 97 healthy volunteers, 35 asbestos-exposed workers, and 42 MM patients were analyzed. RESULTS: The mean detection range of the new ELISA was 0.12 to 8.97 ng/ml calretinin. The assay demonstrated markedly lower background and significantly higher sensitivity compared to the initially contrived assay that used commercial antibodies. Recovery rate experiments confirmed dependence of calretinin antibody recognition on calcium concentration. Calcium adjustment is necessary for calretinin measurement in EDTA plasma. Spiked-in calretinin revealed high stability in EDTA plasma when stored at room temperature, 4 degrees C, or after repeated freeze/thaw cycles. Median calretinin values in healthy volunteers, asbestos workers, and MM patients were 0.20, 0.33, and 0.84 ng/ml, respectively (p < 0.0001 for healthy vs. MM, p = 0.0036 for healthy vs. asbestos-exposed, p < 0.0001 for asbestos-exposed vs. MM). Median values in patients with epithelioid and biphasic MM were similar. No influence of age, gender, smoking status, or type of medium (plasma/serum) on calretinin values was found. CONCLUSIONS: The novel assay is highly sensitive and applicable to human serum and plasma. Calretinin appears to be a promising marker for the blood-based detection of MM and might complement other markers. However, further studies are required to prove its usefulness in the diagnosis of MM patients.

Determinants of plasma calretinin in patients with malignant pleural mesothelioma.

OBJECTIVE: Calretinin is a well-known immunohistochemical tissue marker in the diagnosis of malignant mesothelioma. Promising results also indicate the use in early detection. In the present cross-sectional survey, correlations of calretinin plasma levels with clinical features were investigated. Plasma samples of 60 patients with malignant pleural mesothelioma (MPM) and 111 cancer-free controls formerly exposed to asbestos were compared. Calretinin concentrations were determined in plasma using an enzyme-linked immunosorbent assay (ELISA). RESULTS: The median concentration was higher in MPM patients than in controls (0.79 vs. 0.23 ng/ml; p < 0.0001). Patients with epithelioid MPM or biphasic MPM had higher calretinin plasma levels than patients with sarcomatoid MPM. Strong expression of calretinin in the tumor tissue was associated with higher plasma levels. Preoperative patients showed higher levels of calretinin than patients after thoracic surgery (1.20 vs. 0.67 ng/ml; p = 0.096). The suitability of plasma calretinin has been confirmed as a tumor marker in the differential diagnosis of epithelioid MPM. The value of plasma calretinin for therapy monitoring or as a prognostic marker should be further investigated.

Digital PCR for the Analysis of MYC Copy Number Variation in Lung Cancer.

BACKGROUND: MYC (v-myc avian myelocytomatosis viral oncogene homolog) is one of the most frequently amplified genes in lung tumors. For the analysis of gene copy number variations, dPCR (digital PCR) is an appropriate tool. The aim of our study was the assessment of dPCR for the detection of MYC copy number variations (CNV) in lung tissue considering clinicopathological parameters. Material and Methods. MYC status was analyzed with dPCR as well as qPCR (quantitative PCR) using gDNA (genomic DNA) from tumor and adjacent nontumor tissue samples of lung cancer patients. The performance of MYC was estimated based on the AUC (area under curve). RESULTS: The results of the MYC amplification correlated significantly between dPCR and qPCR (r S = 0.81, P < 0.0001). The MYC copy number revealed by dPCR showed statistically significant differences between tumor and adjacent nontumor tissues. For discrimination, a sensitivity of 43% and a specificity of 99% were calculated, representing 55 true-positive and one false-positive tests. No statistically significant differences could be observed for age, sex, and smoking status or the clinicopathological parameters (histological subtype, grade, and stage). CONCLUSION: The results of the study show that dPCR is an accurate and reliable method for the determination of MYC copy numbers. The application is characterized by high specificity and moderate sensitivity. MYC amplification is a common event in lung cancer patients, and it is indicated that the determination of the MYC status might be useful in clinical diagnostics.

Circulating long non-coding RNA GAS5 (growth arrest-specific transcript 5) as a complement marker for the detection of malignant mesothelioma using liquid biopsies.

BACKGROUND: For the detection of malignant mesothelioma additional markers are needed besides the established panel consisting of calretinin and mesothelin. The aim of this study was the identification and verification of long non-coding RNAs (lncRNAs) as complementing circulating markers. METHODS: Candidate lncRNAs were identified in silico using previously published RNA expression profiles and verified using quantitative PCR (qPCR) in mesothelioma cell lines as well as human plasma samples from mesothelioma patients and asbestos-exposed controls. RESULTS: GAS5 (growth arrest-specific transcript 5) as a single marker is marked by a low sensitivity of 14%, but the combination of GAS5 with calretinin and mesothelin increased the panel's sensitivity from 64 to 73% at a predefined specificity of 97%. Circulating GAS5 is not affected by pleurectomy before blood collection, age, or smoking status. CONCLUSIONS: GAS5 is verified as an appropriate circulating marker for the supplement of calretinin and mesothelin to detect malignant mesothelioma. Although the sensitivity of GAS5 is too low for the use as a single marker, the addition of GAS5 as a third marker improves the performance of the established marker panel. The benefit of GAS5 for the detection of malignant mesothelioma at early stages needs to be validated in a prospective study.

Prediagnostic detection of mesothelioma by circulating calretinin and mesothelin - a case-control comparison nested into a prospective cohort of asbestos-exposed workers.

Malignant mesothelioma (MM) is strongly associated with a previous asbestos exposure. To improve timely detection of MM in asbestos workers, better screening tools - like minimally-invasive biomarkers - are desirable. Between 2008 and 2018 2,769 patients with benign asbestos-related diseases were recruited to participate in annual screens. Using a nested case-control design the protein markers calretinin and mesothelin were determined by enzyme-linked immunosorbent assays in prediagnostic plasma samples of 34 MM cases as well as 136 matched controls from the cohort. Conditional on a pre-defined specificity of 98% for calretinin and 99% for mesothelin the markers reached individual sensitivities of 31% and 23%, respectively, when including the incident cases with samples taken between one and 15 months before diagnosis. The combination of both markers increased the sensitivity to 46% at 98% specificity. Marker complementation increased with earlier sampling. The marker combination improves the sensitivity of the individual markers, indicating a useful complementation and suggesting that additional markers may further improve the performance. This is the first prospective cohort study to evaluate a detection of MM by calretinin and its combination with mesothelin up to about a year before clinical diagnosis. Whether an earlier diagnosis will result in reduced mortality has yet to be demonstrated.

Circulating miR-132-3p as a Candidate Diagnostic Biomarker for Malignant Mesothelioma.

The use of circulating microRNAs as biomarkers has opened new opportunities for diagnosis of cancer because microRNAs exhibit tumor-specific expression profiles. The aim of this study was the identification of circulating microRNAs in human plasma as potential biomarkers for the diagnosis of malignant mesothelioma. For discovery, TaqMan Low Density Array Human MicroRNA Cards were used to analyze 377 microRNAs in plasma samples from 21 mesothelioma patients and 21 asbestos-exposed controls. For verification, individual TaqMan microRNA assays were used for quantitative real-time PCR in plasma samples from 22 mesothelioma patients and 44 asbestos-exposed controls. The circulating miR-132-3p showed different expression levels between mesothelioma patients and asbestos-exposed controls. For discrimination, sensitivity of 86% and specificity of 61% were calculated. Circulating miR-132-3p in plasma was not affected by hemolysis and no impact of age or smoking status on miR-132-3p levels could be observed. For the combination of miR-132-3p with the previously described miR-126, sensitivity of 77% and specificity of 86% were calculated. The results of this study indicate that miR-132-3p might be a new promising diagnostic biomarker for malignant mesothelioma. It is indicated that the combination of miR-132-3p with other individual biomarkers improves the biomarker performance.

Assessment of potential predictors of calretinin and mesothelin to improve the diagnostic performance to detect malignant mesothelioma: results from a population-based cohort study.

OBJECTIVES: Mesothelin and calretinin are blood-based markers for malignant mesothelioma. The objective of this study was to analyse the markers in plasma samples from cancer-free men and to identify factors influencing their concentrations to minimise false-positive test results when using these markers for the early detection of malignant mesothelioma. SETTING: The present analyses used data and archived blood samples of the population-based Heinz Nixdorf Recall Study among elderly people collected from 2011 to 2014. PARTICIPANTS: A total of 569 men (median age 70 years) without a malignant disease at the time of blood sampling were selected for these analyses. PRIMARY AND SECONDARY OUTCOME: Mesothelin and calretinin concentration in plasma samples. RESULTS: We observed 24 mesothelin concentrations ≥1.5 nM (specificity 95.8%, 95% CI 93.8% to 97.2%) and 34 calretinin concentrations ≥1.0 ng/mL (specificity 94.0%, 95% CI 91.7% to 95.7%). Only five men had both markers above these cut-offs. Renal dysfunction and hypertension were major predictors of elevated mesothelin in addition to age. Regarding calretinin, the effect of renal dysfunction was slightly weaker and hypertension was not associated with increased concentrations. However, a diagnosis of cancer after blood collection and bronchial asthma were associated with positive calretinin results. CONCLUSIONS: The combined determination of mesothelin and calretinin results in only few false-positive marker tests. Both markers are mainly influenced by renal dysfunction. The determination of cystatin C concentrations may be informative when interpreting the test results.

Combination of MiR-103a-3p and mesothelin improves the biomarker performance of malignant mesothelioma diagnosis.

BACKGROUND: For the detection of malignant mesothelioma no single biomarker with reasonable sensitivity and specificity has been described so far. Mesothelin, the most prominent blood-based biomarker, is characterized by high specificity but low sensitivity. It might be reasonable to combine biomarkers of different molecular classes in order to improve the overall performance. The aim of this study was to assess the performance of the combination of mesothelin and miR-103a-3p as blood-based biomarker for mesothelioma. METHODS/PRINCIPAL FINDINGS: Mesothelin concentration in plasma and miR-103a-3p levels in the cellular blood fraction were analyzed in 43 male mesothelioma patients and 52 male controls formerly exposed to asbestos. For the discrimination of epithelioid and biphasic mesothelioma from asbestos-exposed controls mesothelin and miR-103a-3p showed 74% and 89% sensitivity and 85% and 63% specificity, respectively. For the combination of mesothelin and miR-103a-3p a sensitivity of 95% and a specificity of 81% were calculated. CONCLUSIONS/SIGNIFICANCE: The results of this study show that the combination of mesothelin and miR-103a-3p improves the diagnostic performance of individual blood-based biomarker to detect malignant mesothelioma. The obtained results indicate that the use of biomarkers of different molecular classes might be a reasonable approach to assemble a biomarker panel.

Cross-contamination of a UROtsa stock with T24 cells--molecular comparison of different cell lines and stocks.

BACKGROUND: UROtsa is an authentic, immortalized human urothelial cell line that is used to study the effects of metals and other toxic substances, mostly in the context of bladder cancer carcinogenesis. Unusual properties on the molecular level of a provided UROtsa cell line stock prompted us to verify its identity. METHODS: UROtsa cell line stocks from different sources were tested on several molecular levels and compared with other cell lines. MicroRNA and mRNA expression was determined by Real-Time PCR. Chromosome numbers were checked and PCR of different regions of the large T-antigen was performed. DNA methylation of RARB, PGR, RASSF1, CDH1, FHIT, ESR1, C1QTNF6, PTGS2, SOCS3, MGMT, and LINE1 was analyzed by pyrosequencing and compared with results from the cell lines RT4, T24, HeLa, BEAS-2B, and HepG2. Finally, short tandem repeat (STR) profiling was applied. RESULTS: All tested UROtsa cell line stocks lacked large T-antigen. STR analysis unequivocally identified our main UROtsa stock as the bladder cancer cell line T24, which was different from two authentic UROtsa stocks that served as controls. Analysis of DNA methylation patterns and RNA expression confirmed their differences. Methylation pattern and mRNA expression of the contaminating T24 cell line showed moderate changes even after long-term culture of up to 56 weeks, whereas miRNAs and chromosome numbers varied markedly. CONCLUSIONS: It is important to check the identity of cell lines, especially those that are not distributed by major cell banks. However, for some cell lines STR profiles are not available. Therefore, new cell lines should either be submitted to cell banks or at least their STR profile determined and published as part of their initial characterization. Our results should help to improve the identification of UROtsa and other cells on different molecular levels and provide information on the use of urothelial cells for long-term experiments.

Identification of miRNA-103 in the cellular fraction of human peripheral blood as a potential biomarker for malignant mesothelioma--a pilot study.

BACKGROUND: To date, no biomarkers with reasonable sensitivity and specificity for the early detection of malignant mesothelioma have been described. The use of microRNAs (miRNAs) as minimally-invasive biomarkers has opened new opportunities for the diagnosis of cancer, primarily because they exhibit tumor-specific expression profiles and have been commonly observed in blood of both cancer patients and healthy controls. The aim of this pilot study was to identify miRNAs in the cellular fraction of human peripheral blood as potential novel biomarkers for the detection of malignant mesothelioma. METHODOLOGY/PRINCIPAL FINDINGS: Using oligonucleotide microarrays for biomarker identification the miRNA levels in the cellular fraction of human peripheral blood of mesothelioma patients and asbestos-exposed controls were analyzed. Using a threefold expression change in combination with a significance level of p<0.05, miR-103 was identified as a potential biomarker for malignant mesothelioma. Quantitative real-time PCR (qRT-PCR) was used for validation of miR-103 in 23 malignant mesothelioma patients, 17 asbestos-exposed controls, and 25 controls from the general population. For discrimination of mesothelioma patients from asbestos-exposed controls a sensitivity of 83% and a specificity of 71% were calculated, and for discrimination of mesothelioma patients from the general population a sensitivity of 78% and a specificity of 76%. CONCLUSIONS/SIGNIFICANCE: The results of this pilot study show that miR-103 is characterized by a promising sensitivity and specificity and might be a potential minimally-invasive biomarker for the diagnosis of mesothelioma. In addition, our results support the concept of using the cellular fraction of human blood for biomarker discovery. However, for early detection of malignant mesothelioma the feasibility of miR-103 alone or in combination with other biomarkers needs to be analyzed in a prospective study.

Cancer mortality in a surveillance cohort of German males formerly exposed to asbestos.

The objective of this analysis was the estimation of the cancer risks of asbestos and asbestosis in a surveillance cohort of high-exposed German workers. A group of 576 asbestos workers was selected for high-resolution computer tomography of the chest in 1993-1997. A mortality follow-up was conducted through 2007. Standardised mortality ratios (SMRs) were calculated and Poisson regression was performed to assess mesothelioma risks. A high risk was observed for pleural mesothelioma (SMR 28.10, 95% CI 15.73-46.36) that decreased after cessation of exposure (RR 0.1; 95% CI 0.0-0.6 for > or =30 vs. <30 years after last exposure). Asbestosis was a significant risk factor for mesothelioma (RR 6.0, 95% CI 2.4-14.7). Mesothelioma mortality was still in excess in former asbestos workers although decreasing after cessation of exposure. Fibrosis was associated with subsequent malignancy.

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.