Claudin 6 (CLDN6)

Class

Claudin 6-directed antibody-drug conjugate (microtubule-inhibitor payload)

Pathway

Tight-junction protein overexpressed in ovarian, endometrial, testicular and other solid tumors

Claudin 6 (CLDN6) is a member of the claudin family of proteins that form tight junctions, the structures that seal adjacent epithelial cells together and control what passes between them. CLDN6 is normally expressed only transiently during early embryonic development and is essentially absent from healthy adult tissue. However, it becomes aberrantly reactivated on the surface of several solid tumor types, including ovarian, endometrial, and testicular germ cell cancers. This near-exclusive tumor expression, combined with its accessibility on the cell surface, makes CLDN6 an attractive antigen for tumor-selective therapies. One such approach is the antibody-drug conjugate (ADC), a molecule that pairs an antibody engineered to recognize CLDN6 with a cytotoxic chemical payload. The antibody portion delivers the payload specifically to CLDN6-expressing cells, sparing normal tissue that lacks the target, while the payload itself is designed to kill dividing cells once inside. This strategy addresses a long-standing challenge in oncology: how to achieve the tumor-killing potency of classical chemotherapy while minimizing the systemic toxicity that broad, non-selective cytotoxic drugs cause. CLDN6-directed therapies are being explored across cancers where this reactivation pattern is documented, offering a route to treat tumor types that have historically had limited targeted-therapy options.