Biological Functions of CLDN6 and Research Progress of Targeted Drugs

Biological Functions of CLDN6 and Research Progress of Targeted Drugs

Claudin-6 (CLDN6) is a key member of the Claudin (CLDNs) tight junction protein family alongside the well-characterized CLDN18.2. By forming four-transmembrane structure, CLDN6 stabilizes intercellular tight junctions and thus plays a vital role in maintaining cell polarity and modulating epithelial barrier permeability.

Figure 1. Molecular mechanisms and functional roles of CLDN6 in various cancers^[1]

Core Value of CLDN6

In terms of its expression profile, CLDN6 exhibits a typical carcinoembryonic antigen-like pattern, with closely intertwined biological and clinical significance.

1. High targeting specificity and satisfactory safety. CLDN6 is actively expressed during embryonic development yet silenced in healthy adult tissues, while abnormally reactivated in multiple malignant tumors. This unique "tumor-suppressive" properties lays the foundation for CLDN6 to serve as an ideal therapeutic target.

2. Easily identifiable and precisely binding. CLDN6 contains two extracellular domains fully exposed on the cell surface, facilitating precise recognition and binding by antibodies.

3. Broad therapeutic indications and substantial clinical demand. CLDN6 is aberrantly overexpressed in multiple prevalent solid tumors including ovarian cancer, testicular cancer, lung cancer and pancreatic cancer, and its overexpression correlates with poor prognosis, demonstrating robust clinical development potential.

4. High versatility across drug formats. CLDN6 has attracted extensive research across cutting-edge therapeutic modalities, including antibody-drug conjugates (ADCs), bispecific antibodies, CAR-T cells and mRNA vaccines. Its druggability has been preliminarily validated in multiple clinical trials.

AACR：China Insights  

Owing to its unique expression pattern and vital biological functions, CLDN6-targeted therapies have emerged as frontiers in novel anticancer drug development, with multiple technical approaches rapidly advancing into clinical stages.

This year at AACR, Chinese pharmaceutical enterprises presented landmark CLDN6 research data, further validating the immense therapeutic potential in the treatment of solid tumors. From bispecific antibodies to ADCs and now vaccines, CLDN6 has become a strategic focus in solid tumor R&D.

Affinity Biopharmaceutical presented preclinical data on its CLDN6-CD3 TMEA-TCE, IMD-1743 (AACR 2026 Poster #2636). Leveraging a distinctive tumor microenvironment activation technology (TMEA), this candidate demonstrated potent antitumor efficacy without inducing cytokine release syndrome (CRS).  Qilu Pharmaceutical, meanwhile, unveiled first-in-human trial results of its CLDN6-targeting ADC, QLS5132, in patients with platinum-resistant ovarian cancer (AACR 2026 Poster #CT037), serving as further validation of CLDN6 clinical utility in solid tumor treatment. In addition, Sequencio Therapeutics reported promising data of its CLDN6 therapeutic vaccine in colon cancer models (AACR 2026 Poster #4375), highlighting broad prospects for CLDN6-based immunotherapy.

KACTUS Supplies Comprehensive CLDN6 Research Solutions

To accelerate the CLDN6 R&D process, KACTUS has comprehensively established a full portfolio of CLDN6 membrane protein products with flexible options for customers. All products undergo rigorous functional validation to ensure high purity, native conformation, and biological activity. Furthermore, leveraging its established expertise in membrane protein expression, KACTUS also provides highly customized services, including specific tag design and tailored buffer systems, thereby delivering end-to-end solutions for CLDN6-related drug development.

Reference

[1] Yang Z, Li M, Yang J, Du J, Li S, Jin Q, Quan C, Qu H. CLDN6 in Cancer: Biology, Clinical Significance, and Emerging Therapeutic Strategies. Pharmacol Res. 2026 Jun 7:108276. doi: 10.1016/j.phrs.2026.108276. Epub ahead of print. PMID: 42259433.