Interpatient variability in mesothelin expression necessitates its evaluation before gastric cancer immunotherapy.

Aims: Mesothelin (MSLN) was applied for the immunotherapy of ovarian cancer and mesothelioma with a minimum expression of 60% to obtain a clinical response. Here, the authors evaluated MSLN expression as a potential target of gastric adenocarcinoma immunotherapy. Materials & methods: The expression of MSLN was evaluated by immunohistochemistry and was reported in primary tumor (PT) and metastatic tumor (MT) sites. Results: The results showed that only 17.1% and 13.5% of the patients had 60% or more MSLN expression in PT and MT sites, respectively. The expression of MSLN in PTs and MTs was not influenced by Lauren classification, neoadjuvant therapy or tumor stage. Conclusions: Interpatient variability in MSLN expression necessitates its evaluation before MSLN-based gastric cancer immunotherapy.