Mesothelin Expression in Patients with High-Grade Serous Ovarian Cancer Does Not Predict Clinical Outcome But Correlates with CD11c(+) Expression in Tumor

INTRODUCTION: Mesothelin (MSLN) is overexpressed in several tumors including ovarian cancer and is the target of current trials. There is limited and conflicting data on MSLN prognostic impact in ovarian cancer. METHODS: We performed a retrospective study on patients with high-grade serous ovarian cancer, analyzing MSLN expression by immunohistochemistry and examining the correlation of its expression to overall and progression-free survival. Correlations of expression of MSLN, CD8, and macrophage markers in different tumor compartments were also investigated. RESULTS: Positive MSLN expression was detected in 55.1% of primary tumors and 51.5% of the metastases. MSLN expression was not correlated with survival. We observed a significant positive correlation (r = 0.34, p = 0.01) between MSLN expression in the metastatic site and CD11c expression in total tumor area and perivascular area in the primary tumor. CONCLUSION: Our results show that MSLN expression does not correlate with clinical outcome. The impact of the correlation between MSLN and CD11c(+) cells on immunotherapy outcome should be further explored. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s12325-020-01520-w) contains supplementary material, which is available to authorized users.