CLDN18.2 in PDAC: KRAS and Hyperglycaemia Create a Resistance Mechanism: Gut | 2026

• CLDN18.2 is emerging as a therapeutic target in gastrointestinal cancers, but its benefit in pancreatic ductal adenocarcinoma has been limited.

• This study identifies a key resistance mechanism: KRAS mutation and hyperglycaemia drive O-GlcNAcylation of CLDN18.2, a sugar-based post-translational modification.

• The modification occurs at the T204 site of CLDN18.2 and changes its cellular behaviour.

• Instead of remaining on the tumour cell membrane where CLDN18.2-targeted therapies can bind effectively, O-GlcNAcylated CLDN18.2 accumulates in the cytoplasm.

• This loss of membrane localization may explain why some pancreatic cancers expressing CLDN18.2 still respond poorly to CLDN18.2-targeted therapy.

• O-GlcNAcylated CLDN18.2 is not just a passive resistance marker; it actively promotes pancreatic cancer migration, invasion, and metastasis.

• Mechanistically, O-GlcNAcylated CLDN18.2 shows reduced binding to PTP1B, leading to increased tyrosine phosphorylation.

• This allows CLDN18.2 to recruit Src through its SH2 domain, activating Src signaling and enhancing aggressive tumour biology.

• Genetic blockade of the O-GlcNAcylation site, using the T204A mutation, restored CLDN18.2 membrane localization and reduced tumour progression in experimental models.

• Pharmacological inhibition of O-GlcNAcylation produced similar benefits, suggesting that this pathway is therapeutically targetable.

• Low-dose MRTX1133, a KRASG12D inhibitor, reduced CLDN18.2 O-GlcNAcylation and restored membrane localization in KRAS-mutant PDAC models.

• Combining low-dose MRTX1133 with CLDN18.2-targeted therapy improved antitumour efficacy with minimal side effects in preclinical models.

• The study suggests that CLDN18.2 testing should not focus only on expression level; subcellular localization may be equally important.

• Hyperglycaemia may be clinically relevant because metabolic status could influence CLDN18.2 modification, localization, and therapeutic response.

• This is an important translational study, but the proposed strategy still requires clinical validation before routine use.

Bottom line: KRAS mutation and hyperglycaemia can convert CLDN18.2 from a membrane-accessible therapeutic target into a cytoplasmic, pro-metastatic, therapy-resistant protein. Targeting KRAS-driven O-GlcNAcylation may restore CLDN18.2-targeted therapy sensitivity in pancreatic cancer.