Joel Thimpont

Diagnostic Performance of Soluble Mesothelin and Megakaryocyte Potentiating Factor in Mesothelioma

RATIONALE Soluble mesothelin (SM) is currently the reference serum biomarker of malignant pleural mesothelioma (MPM). Megakaryocyte potentiating factor (MPF), which originates from the same precursor protein, is potentially more sensitive, yet lacks validation. OBJECTIVES To analyze the diagnostic performance of MPF as an MPM biomarker and compare this performance with SM. METHODS A total of 507 participants were enrolled in six cohorts: healthy control subjects (n = 101), healthy asbestos-exposed individuals (n = 89), and patients with benign asbestos-related disease (n = 123), benign respiratory disease (n = 46), lung cancer (n = 63), and MPM (n = 85). Sera were analyzed for SM and MPF levels using the Mesomark and Human MPF ELISA kit, respectively. MEASUREMENTS AND MAIN RESULTS SM and MPF levels differed significantly between patients with MPM and participants from each other cohort (P < 0.001). Receiver operating characteristics curve analysis did not reveal a significant difference between both markers in area under curve (AUC) for distinguishing MPM from all cohorts jointly (SM = 0.871, MPF = 0.849; P = 0.28). At 95% specificity, SM and MPF had a sensitivity of 64% (cutoff = 2.00 nmol/L) and 68% (cutoff = 12.38 ng/ml), respectively. Combining both markers did not improve the diagnostic performance. CONCLUSIONS In this prospective multicenter study, MPF is validated as a highly performant MPM biomarker. The similar AUC values of SM and MPF, together with the limited difference in sensitivity, show that both serum biomarkers have an equivalent diagnostic performance.

The effect of clinical covariates on the diagnostic and prognostic value of soluble mesothelin and megakaryocyte potentiating factor

BACKGROUND Soluble mesothelin (SM) and megakaryocyte potentiating factor (MPF) are serum biomarkers of mesothelioma. This study examined the effect of clinical covariates on biomarkers levels and their diagnostic and prognostic value. METHODS Five hundred ninety-four participants were enrolled in a multicenter study, including 106 patients with mesothelioma and 488 control subjects. Multiple linear regression analyses were used to identify which covariates were independently associated with SM and MPF levels. The effect of these covariates on the diagnostic accuracy was evaluated with receiver operating characteristics curve analysis. In patients with mesothelioma, survival analysis was performed with Cox regression. RESULTS SM and MPF levels were independently associated with age, glomerular filtration rate (GFR), and BMI in control subjects and with GFR and tumor stage in patients with mesothelioma. The diagnostic accuracy of SM and MPF was significantly affected by the distribution of these covariates in the study population. The patients with mesothelioma were best discriminated from the control subjects with either the youngest age, the highest GFR, or the largest BMI. Furthermore, the control subjects were significantly better differentiated from stage II to IV than from stage I mesothelioma. MPF, not SM, was an independent negative prognostic factor, but only if adjusted for the biomarker-associated covariates. CONCLUSIONS SM and MPF levels were affected by the same clinical covariates, which also had a significant impact on their diagnostic and prognostic value. To improve the interpretation of biomarker results, age, GFR, and BMI should be routinely recorded. Approaches to account for these covariates require further validation, as does the prognostic value of SM and MPF.

Serial Measurements of Mesothelioma Serum Biomarkers in Asbestos-Exposed Individuals: A Prospective Longitudinal Cohort Study

Introduction:Soluble mesothelin (SM) and megakaryocyte potentiating factor (MPF) are serum biomarkers of mesothelioma. This study aims to examine the longitudinal behavior of SM and MPF in controls to gain insight in the optimal use of these biomarkers in screening. Methods:Asbestos-exposed individuals, with no malignant disease at inclusion, were surveilled for 2 years with annual measurements of SM and MPF. Fixed thresholds were set at 2.10 nmol/L for SM and 13.10 ng/ml for MPF. Longitudinal biomarker analysis, using a random intercept model, estimated the association with age and glomerular filtration rate (GFR), and the intraclass correlation. The latter represents the proportion of total biomarker variance accounted for by the between-individual variance. Results:A total of 215 participants were included, of whom 179 and 137 provided a second sample and third sample, respectively. Two participants with normal SM and MPF levels presented afterward with mesothelioma and lung cancer, respectively. Participants with elevated biomarker levels were typically older and had a lower GFR. During follow-up, biomarker levels significantly increased. Longitudinal analysis indicated that this was in part due to aging, while changes in GFR had a less pronounced effect on serial biomarker measurements. SM and MPF had a high intraclass correlation of 0.81 and 0.78, respectively, which implies that a single biomarker measurement and fixed threshold are suboptimal in screening. Conclusions:The longitudinal behavior of SM and MPF in controls indicates that a biomarker-based screening approach can benefit from the incorporation of serial measurements and individual-specific screening rules, adjusted for age and GFR. Large-scale validation remains nevertheless mandatory to elucidate whether such an approach can improve the early detection of mesothelioma.