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

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. The expression of MSLN was evaluated by immunohistochemistry and was reported in primary tumor (PT) and metastatic tumor (MT) sites. 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. Interpatient variability in MSLN expression necessitates its evaluation before MSLN-based gastric cancer immunotherapy.