Research advances in targeting claudin 18.2 in pancreatic ductal adenocarcinoma treatment

Table 1 Summary of pancreatic cancer research involving analysis of claudin 18.2 expression

Experimental goal	Number/type of cases	Core results	Conclusions	Ref.
Study the expression of CLDN18.2 in normal pancreatic tissue, primary lesions, metastases, and intra-individual matched samples in patients with PDAC, NEN, and acinar cell carcinoma	24 cases of normal pancreatic tissue, 202 samples of primary lesions, 84 cases with metastasis, and 48 intra-individual matched samples	Positive rate: 59.2% in primary PDAC. 20% in NEN. 69.4% in lymph node metastasis. 65.7% in liver metastasis	In principle, many pancreatic cancer patients can benefit from CLDN18.2-based targeted therapy	Wöll et al[24]
Study on the expression of CLDN18.2 in PDAC paraffin specimens and prognosis in patients undergoing curative pancreatectomy	309 cases of PDAC treated with curative pancreatectomy	30.4% of patients had ≥ 75% of tumor cells with a staining intensity of ≥ 2+; median OS of patients with CLDN18.2 positivity (30 months) was significantly longer than that of patients with CLDN18.2 negativity (18 months)	In PDAC patients with lymph node metastasis and perineural invasion, CLDN18.2 expression can be used as a prognostic indicator	Lyu et al[25]
Study on the relationship between CLDN18.2 expression and EMT using PDAC tissue microarrays and whole sections	TMA cohort: 302 cases. Whole slide cohort: 84 cases. Precancerous lesion analysis: 10 cases with PanIN	The CLDN18.2 positivity rate correlated significantly with the degree of pathological differentiation of PDAC. None of the 6 vimentin-positive cases expressed CLDN18.2. All 10 cases of PanIN were CLDN18.2 positive, while the adjacent normal ductal epithelium was negative	Loss of CLDN18.2 expression is related to tumor invasion and metastasis. CLDN18.2 may be involved in early carcinogenic transformation and can be used as a marker for early diagnosis of PDAC or monitoring of precancerous lesions	Zhang et al[26]
Study on the correlation between CLDN18.2 expression and survival in patients with resectable PDAC	68 PDAC patients who underwent surgery	54.4% of cases were CLDN18.2 positive (30.8% with IHC staining intensity of 1+, 16.2% with 2+, and 7.4% with 3+)	CLDN18.2 can serve as a prognostic marker for PDAC	Kayikcioglu and Yüceer[27]

CLDN18.2: Claudin 18.2; PDAC: Pancreatic ductal adenocarcinoma; NEN: Neuroendocrine neoplasia; EMT: Epithelial-mesenchymal transition; TMA: Tissue microarray; PanIN: Pancreatic intraepithelial neoplasia; IHC: Immunohistochemistry; OS: Overall survival.