Mesothelin family proteins and diagnosis of mesothelioma: analytical evaluation of an automated immunoassay and preliminary clinical results.

Background: Studies have suggested that soluble mesothelin-related protein (SMRP) can be used as a serum marker of malignant mesothelioma.

Methods: We assessed the analytical performance of the Mesomark (Fujirebio Diagnostic) two-step ELISA on an automated analyser and performed a preliminary clinical evaluation. The precision of the assay and the in vitro effect of interfering substances on SMRP concentrations were investigated. The serum marker was analysed in 109 healthy subjects never exposed to asbestos, 26 healthy subjects exposed to asbestos, 33 patients with asbestosis, 33 with asbestos-related pleural plaques, 10 with non-malignant pleural diseases, 30 with lung cancer and 24 with histological diagnosis of pleural mesothelioma.

Results: Using the International Mesothelioma Interest Group classification, there were nine stage IV, two stage III, four stage II and nine stage I patients. SMRP concentrations of 4.75, 11.0 and 14 nmol/mL showed a total imprecision of 3.5%, 3.1% and 3.8%. The detection limit was 0.035 nmol/mL; the mean SMRP concentration of 0.63 nmol/mL was associated with a coefficient of variation of 10%. There was no effect (p>0.05) of interfering substances. Serum samples from patients with established pleural mesothelioma had significantly higher (p<0.05) concentrations of SMRP than control healthy and patient groups.

Conclusions: SMRP measured on automated systems could be useful for the diagnosis of mesothelioma in routine clinical practice.