Mesothelin Levels Research Articles

Assessment of the clinicopathological relevance of mesothelin level in plasma, peritoneal fluid, and tumor tissue of epithelial ovarian cancer patients.

Ovarian cancer remains the most lethal gynecologic malignancy. This is due to lack of effective screening, diagnosis predominance in late stage of disease, a high recurrence rate after primary therapy, and poor treatment response in platinum-resistant tumor. Thus, unique biomarkers, predictive of individual disease course, and prognosis are urgently needed. The aim of our study was to assess the clinicopathological significance of plasma, peritoneal fluid, and tumor tissue levels of mesothelin in epithelial ovarian cancer patients. Plasma and peritoneal fluid levels of mesothelin were measured by enzyme-linked immunosorbent assay. Tissue expression of MSLN was evaluated using quantitative real-time polymerase chain reaction. Preoperative plasma mesothelin levels were significantly higher in epithelial ovarian cancer patients in comparison to the patients with benign tumor and controls. There have been noticed significant differences in the plasma mesothelin levels based on International Federation of Gynecology and Obstetrics stage, grade, and histology type. No significant changes were observed between Kurman and Shih type I versus type II epithelial ovarian cancer. Interestingly, peritoneal fluid mesothelin levels revealed significant differences based on both grade and Kurman and Shih-type epithelial ovarian cancer. There were no relevant changes in the mesothelin level in peritoneal fluid between different stages and histology types compared to benign tumor. MSLN expression level in tumor tissue was significantly higher based on stage, grade, and Kurman and Shih-type epithelial ovarian cancer than in the benign masses. In addition, data showed significant higher MSLN expression in endometrioid tumors compared to benign masses and serous tumors. Plasma, peritoneal fluid, and tumor tissue levels of mesothelin positively correlated with level of CA125. Low mesothelin concentrations in plasma were also associated with prolonged patient survival. More importantly, we revealed that plasma mesothelin level was correlated with both peritoneal fluid mesothelin level and tumor MSLN expression. This study highlights that plasma mesothelin level may be a useful noninvasive biomarker surrogate for local tumor mesothelin status in monitoring of epithelial ovarian cancer patients.

Mesothelin and osteopontin as circulating markers of diffuse malignant peritoneal mesothelioma: A preliminary study

BackgroundThe differential diagnosis between diffuse malignant peritoneal mesothelioma (DMPM) and other peritoneal surface malignancies (PSM) is still challenging. Serum mesothelin and osteopontin are increasingly used as markers of pleural mesothelioma, but their role in DMPM is unclear. We assessed the diagnostic and prognostic values of mesothelin, osteopontin, CEA, CA19.9, CA125, and CA15.3 in DMPM patients. MethodsMarkers were dosed before cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) by enzyme-linked immunosorbent assay (ELISA) in 30 DMPM patients and 14 controls with other PSMs. Receiver-operating characteristics (ROC) curve were plotted. The performance of each marker was assessed by the area under the ROC curve (AUC-ROC). ResultsMean mesothelin levels were 7.84 ng/dl (SD = 5.14) in DMPM group and 3.00 ng/dl (SD = 1.25) in controls (P = 0.001). Mean CEA levels were 5.3 ng/dl (SD = 4.7), and 61.96 ng/dl (SD = 112.5) in the two groups (P = 0.008). No statistical difference was seen for osteopontin (P = 0.738), CA19.9 (P = 0.081), CA125 (P = 0.600), and CA15.3 (P = 0.365). AUC-ROC was 0.836 for CA19.9, 0.812 for mesothelin, 0.793 for CEA, and lower for CA125 (0.652), osteopontin (0.531), and CA15.3 (0.481). Using diagnostic cut-offs selected by ROC methodology, sensitivity, specificity, positive and negative predictive values were 70.0%, 100.0%, 100.0%, and 60.9% for mesothelin >5.21 ng/dl, and 90.0%, 85.7%, 93.1%, and 80.0% for CA19.9 < 8.8 U/dl. At multivariate analysis, osteopontin correlated with survival (hazard rate 6.46; 95%CI 1.81–23.05; P = 0.004). ConclusionWhen assessing PSMs of unknown origin, elevated mesothelin with low CA19.9 may increase the suspicion index for DMPM. Ospeopontin warrants further investigations as a prognostic marker for DMPM.

A prospective study to investigate the role of serial serum mesothelin in monitoring mesothelioma

BackgroundRadiological monitoring of malignant pleural mesothelioma (MPM) using modified RECIST criteria is limited by low sensitivity and inter-observer variability. Serial serum mesothelin measurement has shown utility in the assessment of treatment response during chemotherapy but has never been assessed in the longer term follow up of patients.MethodsThis is a single centre study of consecutive patients diagnosed with MPM who received chemotherapy or best supportive care (BSC). Serum mesothelin measurements with paired 6 monthly CT scans were performed following the completion of chemotherapy, or from baseline in the BSC group. Changes in mesothelin were correlated with radiological progression and overall survival.ResultsForty-one patients with MPM were recruited and followed up for a minimum of 12 months (range 12–21 months). The majority of patients (n = 23) received chemotherapy with pemetrexed and cisplatin. Across the cohort a 10% rise in serum mesothelin could predict radiological progression with a sensitivity of 96% (IQR; 79–100) and specificity of 74% (IQR; 50–91). Sensitivity fell to 80% in sarcomatoid only disease. Patients with a rising mesothelin at 6 months had significantly worse overall survival (175 days) compared to stable/falling levels (448 days) (p = 0.003).ConclusionsThis is the first study to assess serum mesothelin’s ability to detect progression of MPM following chemotherapy or during BSC. A 10% rise in serum mesothelin level showed excellent sensitivity at predicting progressive disease. Mesothelin measurement has several advantages over serial CT imaging including reducing hospital visits and cost.

An open-label, phase II study of intravenous anetumab ravtansine, an anti-mesothelin antibody drug conjugate, in pretreated mesothelin-expressing advanced pancreatic cancer.

TPS540 Background: Advanced pancreatic cancer remains one of the deadliest malignancies with median OS of 11 months with the most aggressive therapy regimen. Hence, a need exists for more effective, durable, and targeted therapies. Mesothelin is a membrane associated antigen overexpressed in most pancreatic adenocarcinomas. The biological function of mesothelin remains unknown but it is an internalizing antigen. Given its limited expression in normal tissue and high expression in malignant cells, mesothelin is an excellent target for antibody directed cytotoxic drug delivery. Anetumab ravtansine (AR) is an ADC consisting of a fully human IgG1 antibody directed at mesothelin and conjugated to tubulin-binding toxophore, DM4 (maytansine derivative). Preclinical efforts have shown antiproliferative activity in mesothelin positive cancer cell lines and 75% tumor regression in pancreatic xenograft models (Golfier S, et al. Mol Cancer Ther 13(6):1537-48, 2014). Methods: This is a multicenter, non-randomized, Phase II study evaluating the efficacy of AR in pretreated mesothelin-expressing advanced pancreatic cancer. The study utilizes minimax, Simon 2-stage design testing 5% null hypothesis versus 21% alternative. If no response among the first 20, trial will terminate early. If at least one response among the first 20, trial will accrue additional 10 patients for maximum of 30. Four or more responses out of 30 will reject the null hypothesis. Significance level (alpha) is 0.1 and power is 90%. Probability of stopping early is 36% if the response rate is 5% or lower. Patients will receive AR infusion at 6.5 mg/kg on Day 1 of 21-day cycle. Primary objective: response rate per RECIST 1.1. Secondary objectives: time to progression; toxicity. Eligibility: measurable disease per RECIST 1.1; no more than two prior chemotherapy regimens; 30% of cells with 2+/3+ mesothelin staining per IHC; no history of keratitis or corneal disease. Correlative studies: serum soluble mesothelin levels and apoptotic factors (CK18, caspase-cleaved fragments) at baseline and throughout the study to predict treatment response/outcome. Enrollment is on-going. Clinical trial information: NCT03023722.

A pilot study of zoledronic acid in the treatment of patients with advanced malignant pleural mesothelioma.

PurposeMalignant pleural mesothelioma (MPM) is a rare malignancy with a dismal median survival of <12 months with current therapy. Single and combination chemotherapy regimens have shown only modest clinical benefit. In preclinical studies, nitrogen-containing bisphosphonates (zoledronic acid) inhibit growth of mesothelioma cells by different mechanisms: inhibition of mevalonate pathway, inhibition of angiogenesis, activation of apoptosis through caspase activation, and alteration in activity of matrix metalloproteinases, thereby affecting invasiveness of cancer cells.Patients and methodsWe investigated the role of zoledronic acid in a pilot, single-arm trial of MPM patients with Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0–2 who had progressed on prior treatments or had not received systemic therapy due to poor PS. Primary end point was composite response rate by modified response evaluation criteria in solid tumors and/or metabolic response by 2-deoxy-2-[fluorine-18]fluoro-d-glucose (18F-FDG) positron emission tomography criteria. Secondary end points were progression-free survival (PFS) and overall survival (OS). Exploratory end points include the effect of zoledronic acid therapy on vascular endothelial growth factor (VEGF), basic fibroblast growth factor, interleukin 8, transforming growth factor beta, mesothelin, and osteopontin levels.ResultsEight male patients (median age of 62 years) with the following clinical characteristics were treated; ECOG PS was 0–2, 75% with epithelioid type, and 62% had prior chemotherapy Overall composite response rate was 12.5% and the clinical benefit rate (response + stable disease) was 37.5%. Median PFS was 2 months (0.5–21 months) and median OS was 7 months (0.8–28 months). No treatment-related toxicities were observed. Lower VEGF levels were predictive of favorable response and mesothelin levels correlated with disease course.ConclusionZoledronic acid shows modest clinical activity without significant toxicity in patients with advanced MPM.

Prognostic significance of soluble mesothelin in malignant pleural mesothelioma: a meta-analysis.

BackgroundSoluble mesothelin is beneficial to detect the progression and the treatment response of malignant pleural mesothelioma. However, the prognostic value of soluble mesothelin in malignant pleural mesothelioma remains unclear.MethodsHazard ratio with 95% CI was used to evaluate the prognostic value of soluble mesothelin and the effect of clinicopathological characteristics on the survival of malignant pleural mesothelioma.ResultsEight eligible studies involving 579 patients were selected for this meta-analysis. The results showed that soluble mesothelin level was significantly correlated with the survival of malignant pleural mesothelioma (pooled HR: 1.958, 95%CI: 1.531-2.504, p = 0.000; heterogeneity test: I2 = 1.1%, p = 0.421). In addition, the survival of malignant pleural mesothelioma was significantly correlated with some clinicopathological characteristics such as tumor histology (HR = 3.214, 95% CI = 2.071-4.988, p = 0.000; heterogeneity test: I2 = 0.0%, p = 0.623) and tumor stage (HR = 2.007; 95% CI = 1.477-2.727; p = 0.000; heterogeneity test: I2 = 0.0%, p = 0.966).ConclusionsThe survival of malignant pleural mesothelioma is significantly correlated with tumor histology and tumor stage. Furthermore, high soluble mesothelin level may lead to a poor prognosis for malignant pleural mesothelioma patients.

Midkine is a potential novel marker for malignant mesothelioma with different prognostic and diagnostic values from mesothelin

BackgroundWe evaluated possible diagnostic and prognostic values of serum midkine in malignant pleural mesothelioma in comparison with those of serum mesothelin, a well-established diagnostic biomarker.MethodsSerum mesothelin and midkine levels were determined with an enzyme-linked immunosorbent assay. We examined specimens from 95 Turkish cases with malignant pleural mesothelioma, 56 metastatic cancers to pleura, 27 other types of benign pleural diseases and 20 benign asbestos pleurisy. The cut-off values were 1.5 nmol/L for mesothelin and 421 pg/mL for midkine.ResultsSensitivity and specificity of mesothelin were 51.6 and 71.4%, 51.6 and 85.2%, and 51.6 and 85% for differentiating mesothelioma from metastatic cancers to pleura, other benign pleural diseases and benign asbestos pleurisy, respectively. Sensitivity and specificity of midkine were 61.1 and 41.1%, 61.1 and 48.1%, and 61.1 and 75% to distinguish mesothelioma from metastatic cancers to pleura, other benign pleural diseases and benign asbestos pleurisy, respectively. Combination of both biomarkers did not improve the differential diagnostic efficacy. Mesothelin levels were elevated in the epitheloid type and in the advanced cases, but were not related to the prognosis. In contrast, elevated baseline levels of midkine were independently associated with a poor prognosis of mesothelioma patients after adjusting for the stage, the histological subtypes and treatment schedules (HR = 1.84; 95% CI: 1.09-3.09) (p = 0.022).ConclusionsSerum mesothelin showed moderate sensitivity and high specificity to differentiate malignant pleural mesothelioma from metastatic malignancy to pleura and from benign pleural diseases. In contrast, midkine was a useful marker for predicting prognosis of mesothelioma patients.

Efficacy of Anti-mesothelin Immunotoxin RG7787 plus Nab-Paclitaxel against Mesothelioma Patient-Derived Xenografts and Mesothelin as a Biomarker of Tumor Response.

Purpose: The purpose of this study was to evaluate the antitumor efficacy of the reduced immunogenicity anti-mesothelin immunotoxin RG7787 plus nab-paclitaxel against primary mesothelioma cell lines and tumor xenografts and the utility of mesothelin as a biomarker of tumor response.Experimental Design: Early-passage human malignant mesothelioma cell lines NCI-Meso16, NCI-Meso19, NCI-Meso21, and NCI-Meso29 were evaluated for sensitivity to RG7787 or nab-paclitaxel alone or in combination. In addition, the antitumor activity of RG7787 plus nab-paclitaxel was evaluated using NCI-Meso16, NCI-Meso21, and NCI-Meso29 tumor xenografts in immunodeficient mice. Serum mesothelin was measured at different time points to determine whether its levels correlated with tumor response.Results: All four primary mesothelioma cell lines highly expressed mesothelin with 41 × 103 to 346 × 103 mesothelin sites per cell and were sensitive to RG7787, with IC50 ranging from 0.3 to 10 ng/mL. Except for NCI-Meso19, these cells were also sensitive to nab-paclitaxel, with IC50 of 10 to 25 ng/mL. In vitro, RG7787 plus nab-paclitaxel led to decreased cell viability compared with either agent alone. In NCI-Meso16 tumor xenografts, treatment with RG7787 plus nab-paclitaxel led to sustained complete tumor regressions. Similar antitumor efficacy was observed against NCI-Meso21 and NCI-Meso29 tumor xenografts. In all three tumor xenograft models, changes in human serum mesothelin correlated with response to therapy and were undetectable in mice with complete tumor regression with RG7787 and nab-paclitaxel.Conclusions: RG7787 plus nab-paclitaxel is very active against primary human mesothelioma cells in vitro as well as in vivo, with serum mesothelin levels correlating with tumor response. These results indicate that this combination could be useful for treating patients with mesothelioma. Clin Cancer Res; 23(6); 1564-74. ©2016 AACR.

Correlation Between Tumor Mesothelin Expression and Serum Mesothelin in Patients with Epithelial Ovarian Carcinoma: A Potential Noninvasive Biomarker for Mesothelin-targeted Therapy.

The cell surface glycoprotein mesothelin is highly expressed in several malignant diseases. Normal mesothelin expression is limited to mesothelial cells lining the pleura, peritoneum, and pericardium, making it a biomarker and an attractive target for cancer therapy. We investigated tumor mesothelin expression and serum mesothelin levels in patients with epithelial ovarian cancer or borderline tumors. In total, 161 patients selected from a previous prospective study were analyzed fortumor mesothelin expressionusing immunohistochemistry and serum mesothelin expressionusing enzyme-linked immunosorbent assay. Eighty-eight (68.8%) epithelial ovarian cancers and eight (24.2%) borderline tumors showed high mesothelin expression, which was associated with shorter progression-free and overall survival. The tumor mesothelin expression status was moderately correlated with serum mesothelin levels in epithelial ovarian cancer patients. Based on receiver operating characteristic analysis, a serum mesothelin level above 2.20nM predicted high tumor mesothelin expression in epithelial ovarian cancer patients (area under the curve=0.81). In 45 patients with recurrent epithelial ovarian cancer, we observed relatively lower levels of serum mesothelin, compared to the level at the primary diagnosis. We also tracked the change in the serum mesothelin level during the course of second-line chemotherapy and found a discrepancy between the clinical response and the serum mesothelin change in some patients, which suggested tumor heterogeneity among the tumor cells with or without mesothelin expression. Serum mesothelin may be a useful noninvasive biomarker surrogate for tumor mesothelin expression in future clinical trials for mesothelin-targeted therapy.

Plasma Mesothelin as a Novel Diagnostic and Prognostic Biomarker in Colorectal Cancer.

Objective Mesothelin is a cell surface protein and overexpressed in many cancers. However, the potential value of mesothelin as plasma biomarker in colorectal cancer has not been explored. The purpose of this study was to identify whether plasma mesothelin is a suitable diagnostic and prognostic biomarker for colorectal cancer.Methods We performed a two-stage case-control study to evaluate plasma mesothelin levels in colorectal cancer using enzyme-linked immunosorbent assay (ELISA). Preoperative and postoperative plasma were collected to examine the level changes influenced by surgery. Receiver operating characteristic (ROC) curves were applied to identify the diagnostic value of plasma mesothelin. We also conducted univariate Kaplan-Meier survival analysis and Cox regression analysis of patients with survival information.Results We found that the plasma mesothelin levels in colorectal cancer patients were significantly higher than that in the controls (P < 0.001) with an AUC value of 0.690 (95% CI = 0.625 to 0.752). Individuals with lower mesothelin level had a longer survival time (adjusted HR = 4.43, 95% CI = 1.93-10.15, P < 0.001). Furthermore, Patients had slightly decreased mesothelin levels in postoperative plasma than preoperative plasma, although the alteration was not statistically significant (P = 0.052).Conclusion Our findings highlight the correlative relationship between plasma mesothelin levels and the presence and progression of colorectal cancer. Plasma mesothelin may be a potential diagnostic and, or prognostic biomarker for colorectal cancer.

P3.03-052 Diagnostic Utility of Mesothelin, Osteopontin and Megakaryocyte Potentiation Factor in Turkish Patients with Malignant Mesothelioma: Topic: Mesothelioma Clinical

Malignant mesothelioma (MM) is an agressive tumor with poor prognosis, thus early assessment is important. We investigated the presence of mesothelin, osteopontin and megakaryocyte potentiation factor (MPF) levels in both sera and pleural effusions of MM patients and compared to the lung cancer, other malignancy, exudative and transudative effusions. Patients were enrolled into 5 study groups as demonstrated in table 1. Serum and pleural mesothelin, osteopontin and MPF levels of study groups were measured with enzyme-linked immunosorbent assay and compared with using convenient statistical methods. Mesothelin and osteopontin levels in both sera and pleural effusions were found to be statistically different among groups (Table 1). Pleural mesothelin and osteopontin levels were significant parameters to differentiate MM from the other groups (p=0.0001; p=0.002 respectively). When cut off value of pleural mesothelin level was set at 169.6ng/mL, sensitivity was 71.4 % and specificity was 88% for MM. When cut off value of pleural osteopontin level was set at 521.25ng/mL, sensitivity was 64.3% and specificity was 80% for MM (Figure 1). Pleural but not sera MPF level of MM patients was significantly higher than patients with lung cancer (p=0.021). Mesothelin, osteopontin and MPF levels can be used as diagnostic bio-markers to detect MM.

Primary malignant pericardial mesothelioma with increased serum mesothelin diagnosed by surgical pericardial resection: A case report.

A 37-year-old female smoker without a history of exposure to asbestos was referred to our hospital with persistent pericardial effusion. Chest computed tomography imaging examination revealed an irregular thickened pericardium with large amounts of pericardial effusion and a small pleural effusion. Fluorodeoxyglucose (FDG) positron emission tomography imaging demonstrated intrapericardial FDG accumulation. Blood tests revealed an increase in serum mesothelin levels. Examination of a surgically resected specimen revealed a grayish-white thickening of the pericardium, with a straw-colored mucinous pericardial effusion. Histopathological examination confirmed the diagnosis of epithelioid malignant mesothelioma. Although the patient's condition temporarily improved, with decreased levels of serum mesothelin during chemotherapy with carboplatin and pemetrexed, she succumbed to cardiac tamponade 18 months after the initial onset of the symptoms. Primary malignant pericardial mesothelioma (PMPM) is an extremely rare and refractory disorder. Thus, an early definitive diagnosis and timely treatment are crucial for the management of PMPM.

Mesothelin as a biomarker for ovarian carcinoma: a meta-analysis.

The objective of this work was to estimate the accuracy of mesothelin as a biomarker for ovarian cancer. A quantitative systematic review was performed. A comprehensive search of the Medline, LILACS, SCOPUS, Embase, Cochrane Central Register of Controlled Trials, Biomed Central, and ISI Web of Science databases was conducted from January 1990 to June 2015. For inclusion in this systematic review, the papers must have measured mesothelin levels in at least two histological diagnoses; ovarian cancer (borderline or ovarian tumor) vs. benign or normal ovarian tissue. For each study, 2 x 2 contingency tables were constructed. We calculated the sensitivity, specificity and diagnostic odds ratio. The verification bias was performed according to QUADAS-2. Statistical analysis was performed with the software Stata 11, Meta-DiSc(r) and RevMan 5.2. Twelve studies were analyzed, which included 1,561 women. The pooled sensitivity was 0.62 (CI 95% 0.58 - 0.66) and specificity was 0.94 (CI 95% 0.92 - 0.95). The DOR was 38.92 (CI 95% 17.82 - 84.99). Our systematic review shows that mesothelin cannot serve alone as a biomarker for the detection of ovarian cancer.

Evaluation of New Biomarkers in the Prediction of Malignant Mesothelioma in Subjects with Environmental Asbestos Exposure.

The purpose of this study was to investigate the potential value of certain biomarkers in predicting the presence of malignant pleural mesothelioma (MPM) in individuals environmentally exposed to asbestos. This prospective study investigated three groups; a control group composed of 41 healthy subjects, an asbestos exposure group consisting of 48 individuals, and a MPM group consisting of 42 patients. Serum levels of soluble mesothelin-related peptide (SMRP), thioredoxin-1 (TRX), epidermal growth factor receptor (EGFR), fibulin-3, syndecan-1 (SDC-1), and mesothelin were determined. Benign pleural plaques were present in 27 (58.3%) of the individuals in the asbestos exposure group. The asbestos exposure group had significantly higher mean TRX, SMRP, and mesothelin levels compared to the control group (p=0.023, p=0.011, and p<0.001, respectively). Compared to the asbestos exposure group, the MPM group had significantly higher mean EGFR, TRX, SMRP, and fibulin-3 levels (p=0.041, p=0.023, p=0.002, and p=0.001, respectively), and significantly lower mean SDC-1 levels (p=0.002). Unlike the other biomarkers, SMRP and TRX levels increased in a graded fashion among the control, asbestos exposure, and MPM groups, respectively. Area under the curve values for SMRP and TRX were 0.86 and 0.72, respectively (95% CI0.79-0.92 and p<0.001 for SMRP, and 95% CI0.62-0.81 and p<0.001 for TRX). The cut-off value for SMRP was 0.62nmol/l (sensitivity: 97.6%, specificity: 68.9%, positive predictive value (PPV): 56.2%, and negative predictive value (NPV): 98.3%) and for TRX was 156.67ng/ml (sensitivity: 92.9%, specificity: 77.6%, PPV: 41.4%, and NPV: 92.1%). The combination of the biomarkers reached a sensitivity of 100%, but had lower specificity (as high as 27.7%). Serum biomarkers may be helpful for early diagnosis of MPM in asbestos-exposed cases. SMRP and TRX increased in a graded fashion from the controls to asbestos exposure and MPM groups. These two seem to be the most valuable biomarkers for the diagnosis of MPM, both individually and in combination.

Validity of mesothelin in occupational medicine practice.

Malignant mesothelioma (MM) is the most serious asbestos-related disease. Its increasing incidence is alarming, suggesting the need for as early diagnosis as possible. This 4.5-year prospective longitudinal study aimed at assessing the benefit of measuring serum mesothelin as a marker for diagnosing malignant mesothelioma in individuals with previous occupational exposure to asbestos, as a part of their clinical follow-up care. The study comprised 309 participants (235 males, 74 females) with a mean age of 58.9 years (standard deviation (SD) = 9.8) and a mean duration of exposure to asbestos dust of 13.4 years (SD = 9.3). From 2009 to June 2013, all subjects were followed at a department of occupational medicine in Olomouc. Apart from the standard parts of medical examination (history, physical examination, simple chest radiographs and spirometry), the patients' serum mesothelin levels were determined by the Mesomark immunoenzymatic diagnostic assay. Statistical analysis of the validity of serum mesothelin level measurement was carried out with respect to the diagnosis of MM. Among the participants, 16 (5.2%) individuals (14 males and 2 females) were diagnosed with malignant mesothelioma. Based on the detected mesothelin levels, their validity for prediction of malignant mesothelioma was calculated as follows: sensitivity - 0.75, specificity - 0.962, positive predictive value - 0.706, negative predictive value - 0.969, positive and negative likelihood ratios - 19.95 and 0.26, respectively, and diagnostic odds ratio - 76.8, at a 95% confidence interval. The high specificity was identified indicating the low false positivity as well. In the case of detecting elevated soluble mesothelin-related peptides (SMRP) levels in formerly asbestos-exposed individuals, the possibility of the presence of MM should be included into the clinical consideration. The high negative predictive value denotes a lower probability of the presence of MM in patients with normal SMRP levels but due to the limiting lower sensitivity this possibility cannot be entirely excluded.

Tumor and organ uptake of 64Cu-labeled MORAb-009 (amatuximab), an anti-mesothelin antibody, by PET imaging and biodistribution studies

ObjectivesTo investigate the effect of the injection dose of MORAb-009 (amatuximab, an anti-mesothelin monoclonal antibody), the tumor size and the level of shed mesothelin on the uptake of the antibody in mesothelin-positive tumor and organs by biodistribution (BD) and positron emission tomography (PET) imaging studies. Methods2-S-(4-Isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-Bn-NOTA) was conjugated to amatuximab and labeled with 64CuCl2 in 0.25M acetate buffer, pH4.2. The resulting 64Cu-NOTA-amatuximab was purified with a PD 10 column. To investigate the dose effect or the effect of tumor size, the BD was performed in groups of nude mice (n=5) with mesothelin-expressing A431/H9 tumors (range, 80–300mm3) one day after iv injection of 64Cu-NOTA-amatuximab (10μCi) containing a total amatuximab dose of 2, 30, or 60μg. The BD and PET imaging were also investigated 3, 24 and 48h after injecting a total dose of 30μg (10μCi for BD), and 2 or 60μg (300μCi for PET), respectively. ResultsComparing the results of the BDs from three different injection doses, the major difference was shown in the uptake (%ID/g) of the radiolabel in tumor, liver and blood. The tumor uptake and blood retention from 30 and 60μg doses were greater than those from 2μg dose, whereas the liver uptake was smaller. The BD studies also demonstrated a positive correlation between tumor size (or the level of shed mesothelin in blood) and liver uptake. However, there was a negative correlation between tumor size (or the shed mesothelin level) and tumor uptake and between tumor size and blood retention. These findings were confirmed by the PET imaging study, which clearly visualized the tumor uptake with the radiolabel concentrated in the tumor core and produced a tumor to liver ratio of 1.2 at 24h post-injection with 60μg amatuximab, whereas the injection of 2μg amatuximab produced a tumor to liver ratio of 0.4 at 24h post-injection. ConclusionOur studies using a nude mouse model of A431/H9 tumor demonstrated that the injection of a high amatuximab dose (30 to 60μg) could provide a beneficial effect in maximizing tumor uptake while maintaining minimum liver and spleen uptakes of the radiolabel, and in facilitating its penetration into the tumor core.

Combined serum and immunohistochemical differentiation between reactive, and malignant mesothelial proliferations

BackgroundMalignant mesothelioma (MM) carries a poor prognosis and response rates to palliative chemotherapy remain low. The diagnosis of malignant mesothelioma is frequently difficult, the most common differential diagnosis being reactive pleural conditions and metastatic adenocarcinoma. Several studies have used immunohistochemical markers to distinguish between reactive and neoplastic mesothelial cells. Soluble mesothelin levels in serum have recently been shown to be highly specific and moderately sensitive for mesothelioma. A combined detection of serum levels of mesothelin and immunohistochemical expression of desmin and EMA are used in order to differentiate between reactive mesothelial proliferations, and malignant mesothelioma of epithelioid type. Patients and methodsThis prospective study includes 17 cases of reactive mesothelial proliferations, 6 cases of atypical mesothelial proliferations and 13 cases of MM. Cases were collected from the Chest Department, Faculty of Medicine, Benha University and International Medical Center (IMC), in the period 2012–2014. Desmin and epithelial membrane antigen (EMA) immunohistochemical staining were performed in all cases and the pattern of expression was analyzed. Soluble mesothelin related peptide (SMRP) was estimated for all cases. ResultsDesmin expression was positive in 88.2%, 0%, and 7.7% of reactive mesothelial proliferations, atypical mesothelial proliferations and MM respectively. EMA was positive in 5.9% of reactive mesothelial proliferation, 100% of atypical mesothelial proliferations and 92.3% of MM cases (P<0.01). The calculated mean SMRP was 6.6nM. SMRP levels were higher than the calculated mean value in 17.6% of studied reactive mesothelial lesions, 66.7% and 76.9% of atypical mesothelial proliferations and MM respectively, which was statistically highly significant correlation (P<0.01). ConclusionCombined estimation of SMRP level and immunohistochemical detection of both EMA and desmin could be a useful tool for differentiation between reactive mesothelial proliferation and malignant mesothelioma.

A Common Polymorphism Within MSLN Affects miR-611 Binding Site and Soluble Mesothelin Levels in Healthy People

Soluble mesothelin related peptide (SMRP) was proposed as a promising diagnostic marker for malignant pleural mesothelioma (MPM). In a previous study, we found that rs1057147 within the 3' untranslated region of MSLN gene was associated with SMRP levels. Thus, we aimed to (1) confirm the previous association on a large series of volunteers and (2) test the hypothesis that the SNP could affect microRNA binding sites. The association analysis was verified in 759 subjects. Then, in silico predictions highlighted miR-611 and miR-887 as candidate miRNAs binding to the polymorphic site. Thus, chimeric constructs bearing the alternative alleles (G > A) were assayed alone or in cotransfection with the miRNA mimics, with dual luciferase reporter assay in non-MPM Met-5A cells. The miRNAs were also assayed by western blot analysis for their ability to down-regulate endogenous mesothelin in the MPM Mero-14 cell line. We confirmed that, among non-MPM volunteers, GG homozygotes have the lowest SMRP levels. When the genotype is taken into account, the specificity of SMRP as biomarker improves from 79.7% to 85.3%. Dual-luciferase assays showed a significantly lower reporter activity when the vector harbored the G allele as compared to A allele. miR-887 mimic caused a reduced reporter activity of vectors harboring A or G alleles, while miR-611 was effective only on the vector harboring the G allele. Transfection of these miRNAs into Mero-14 cells significantly reduced endogenous MSLN protein. SMRP performance as diagnostic biomarker improved by considering the genotype rs1057147. This polymorphism most likely affects a binding site for miR-611.

An antimesothelin-monomethyl auristatin e conjugate with potent antitumor activity in ovarian, pancreatic, and mesothelioma models.

Mesothelin (MSLN) is an attractive target for antibody-drug conjugate therapy because it is highly expressed in various epithelial cancers, with normal expression limited to nondividing mesothelia. We generated novel antimesothelin antibodies and conjugated an internalizing one (7D9) to the microtubule-disrupting drugs monomethyl auristatin E (MMAE) and MMAF, finding the most effective to be MMAE with a lysosomal protease-cleavable valine-citrulline linker. The humanized (h7D9.v3) version, αMSLN-MMAE, specifically targeted mesothelin-expressing cells and inhibited their proliferation with an IC50 of 0.3 nmol/L. Because the antitumor activity of an antimesothelin immunotoxin (SS1P) in transfected mesothelin models did not translate to the clinic, we carefully selected in vivo efficacy models endogenously expressing clinically relevant levels of mesothelin, after scoring mesothelin levels in ovarian, pancreatic, and mesothelioma tumors by immunohistochemistry. We found that endogenous mesothelin in cancer cells is upregulated in vivo and identified two suitable xenograft models for each of these three indications. A single dose of αMSLN-MMAE profoundly inhibited or regressed tumor growth in a dose-dependent manner in all six models, including two patient-derived tumor xenografts. The robust and durable efficacy of αMSLN-MMAE in preclinical models of ovarian, mesothelioma, and pancreatic cancers justifies the ongoing phase I clinical trial.

A serum mesothelin level is a prognostic indicator for patients with malignant mesothelioma in routine clinical practice

BackgroundMalignant mesothelioma (MM) carries a poor prognosis and response rates to palliative chemotherapy remain low. Identifying patients with MM that are unlikely to respond to chemotherapy could prevent futile treatments and improve patient quality of life. Studies have suggested that soluble mesothelin is a potential biomarker for early diagnosis and prognosis of MM. We set out to explore the utility of serum mesothelin in routine clinical practice.MethodsWe conducted a prospective exploratory study of serum mesothelin levels in 53 consecutive patients with MM at our institution between April 2009 and February 2011. Survival was assessed and analysed by mesothelin level as both continuous and categorical variables using Cox regression models. Differences in response rate between treatment groups were assessed by the Kruskal-Wallis Test.ResultsAll 53 patients, who had been given study information agreed to participate. The patients’ median age was 69 (range 24–90). Median mesothelin level was 2.7 nM and this value was used to dichotomize categories: ≤2.7 nM (low) and >2.7 nM (high). The progression free survival (PFS) for low vs high mesothelin was 8.0 vs 5.1 months (HR 1.8, p-0.058). When mesothelin was accessed as a continuous variable for PFS the HR was 1.03 (95% CI: 1.01 - 1.06; p = 0.013). The overall survival (OS) for low vs high mesothelin was 17.2 vs 11.3 months (HR 1.9, p = 0.088). When mesothelin was assessed as a continuous variable for OS the HR was 1.02 (95% CI: 0.99 - 1.04; p = 0.073). Thirty patients received chemotherapy of which 18 had a pre-chemotherapy serum mesothelin level. In these 18 patients, the pre-chemotherapy mesothelin level did not correlate with response.ConclusionsA single random sample provides information about patient prognosis but does not predict treatment response. We suggest further prospective validation of mesothelin testing as a prognostic biomarker.