Immunohistochemical expression of Mesothelin in a series of high grade tubal-ovarian serous carcinoma

Objectives In the current study, the immunohistochemical expression of Mesothelin (MSLN) in a series of high grade tubal-ovarian serous carcinoma (HGSC), was analysed and correlated with BRCA mutation, the stage of development at diagnosis, recurrences, and survival, in order to establish whether the expression of this marker could be useful for predicting the mutational aspects and clinical outcome of this severe malignancy. Material and Methods HGSCs were collected from 73 patients who had been surgically treated at Parma University, from 2001 and 2021. For immunohistochemical study, tissue sections from primary, metastatic and recurrences were incubated with a mouse monoclonal antibody against mesothelin (clone SP74, ready to use, Ventana-Roche). The proportion of mesothelin expression was evaluated according to this percentage of positive cells: 0, 0%, +1<10%, +2, with positivity between 51 and 75%, +3, with positivity between 75% and 95%, +4 with positivity >95%. The scores + 3 and +4 were considered as intense positivity, the scores +2 and +1 instead as weak positivity. A pattern of intense immunoreactivity mixed with weak positivity was defined as heterogeneous. Chi-square test and Fisher’s exact test were performed to investigate the relationship between MSLN expression and clinicopathological data. We compared disease-free survival (DFS), overall survival (OS) and progression-free survival (PFS) differences among groups of MSLN expression and disease stages using the Kaplan–Meier method and log-rank tests. P<0.05 was taken as a level of significance. Results We did not find any significant statistical differences in the MSLN expression between cases with and without BRCA mutation, nor were differences observed between low stages (stage I/II) and higher stages of development (stage III/IV) and metastatic tissue. Some tissue of recurrences and post-chemotherapy showed statistical differences, with a reduction in expression of MSLN compared with the primary neoplasm (respectively p Value: 0.023 and 0.0156). On the contrary, the follow-up revealed that the survival of HGSCs seems to be independent of MSLN expression. Conclusions To summarize, the present study demonstrates that MSLN expression is an independent prognostic factor and it could be used particularly as a potential target for targeting therapy in primary and metastatic neoplasms.