Clinicopathological Features and Prognosis of Resected Pancreatic Ductal Adenocarcinoma Patients with Claudin-18 Overexpression

Claudin-18.2 (CLDN18.2) is specifically expressed in pancreatic precancerous lesions and pancreatic ductal adenocarcinoma (PDAC). We assessed the clinical characteristics of patients with CLDN18.2-overexpressing pancreatic cancer to identify patients who might benefit from CLDN18-targeted treatment. A total of 130 patients with surgically resected PDAC were investigated for the immunohistochemical expression of claudin-18 (CLDN18). The CLDN18 staining intensities (0–3+) and relative proportion of positive tumor cells were analyzed by two independent raters. Tumors positive for CLDN18 expression were defined as ≥80% of tumor cells with 2+ or 3+ staining intensity in a CLDN18 immunohistochemical assay. Positive CLDN18 expression was present in 41/130 (31.5%) surgically resected PDACs and the relative proportion of positive tumor cells and the staining intensity were directly correlated (p < 0.001). Positive CLDN18 expression was significantly associated with well-differentiated tumors (p < 0.001) and less regional node involvement (p = 0.045). The positive CLDN18-expressing group showed no statistical difference in median overall survival (17.4 months vs. 20.6 months, p = 0.770) compared to the negative CLDN18-expressing group. Distant nodal metastasis was more frequent in the positive CLDN18-expressing group (p = 0.011). CLDN18 is frequently expressed in PDAC, and high CLDN18-expressing PDACs showed some different clinicopathologic characteristics. High CLDN18 expression was not associated with prognosis in patients with surgically resected PDAC.