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What is CLDN18.2?

Detecting CLDN18.2 expression identifies a previously undefined patient population in gastric or gastroesophageal junction (G/GEJ) adenocarcinoma.1

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A predictive biomarker that may help you learn more about your patients with advanced G/GEJ cancer¹

  • Claudins are a family of transmembrane proteins.2,3
  • As a component of tight junctions, claudins are involved in the regulation of permeability, barrier function, and polarity of epithelial layers.2,3
  • The ESMO Clinical Practice Guidelines highlight that CLDN18.2 is a new predictive biomarker for patients with advanced gastric cancer.4

Claudins are present throughout the body, but 2 specific isoforms of CLDN18 are localised to certain tissue types5,6

CLDN18.1

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CLDN18.1 is the dominant isoform in normal and malignant lung tissue.

CLDN18.2

Stomach icon

CLDN18.2 is the dominant isoform in normal gastric tissue and is often retained in malignant transformation.

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What Is CLDN18.2? | CLDN18.2 Pathology Hub

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What Is CLDN18.2? | CLDN18.2 Pathology Hub

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What Is CLDN18.2? | CLDN18.2 Pathology Hub

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What Is CLDN18.2? | CLDN18.2 Pathology Hub

What Is CLDN18.2?

Matteo Fassan, MD, PhD

Normal and tumour cell CLDN18.2 staining at 2x magnification

Normal and tumour cell CLDN18 staining at 2x magnification.

Preclinical data have shown that CLDN18.2 may become more exposed as gastric tumours develop5,7

CONFINED IN HEALTHY TISSUE

Diagram showing normal gastric mucosa and CLDN18.2 confined within cellular tight junctions

In normal gastric mucosa, CLDN18.2 is typically buried within tight junctions.5,7

RETAINED AND EXPOSED IN MALIGNANT TRANSFORMATION

Diagram showing retention and exposure of CLDN18.2 during malignant transformation, making it accessible to antibodies

CLDN18.2 is often retained during malignant transformation. CLDN18.2 may be more exposed when cell polarity disruptions and structure loss occur.5,7,8

MAINTAINED IN METASTATIC PROGRESSION

Diagram describing maintained CLDN18.2 expression in lymph node metastases and other distant metastases

CLDN18.2 may also be expressed in lymph node metastases of gastric adenocarcinoma as well as other distant metastatic sites.1,5,9,10

CLDN18.2 expression may be observed in gastric and gastroesophageal adenocarcinoma, as well as other adenocarcinomas.5

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Detecting CLDN18.2 expression identifies a previously undefined patient population1

According to 2 recent global studies in patients with locally advanced unresectable or metastatic G/GEJ adenocarcinoma, ~38% of cases demonstrated ≥75% of tumour cells with moderate-to-strong (2+/3+) membranous CLDN18 staining.11,12

  • Among advanced G/GEJ biomarkers, CLDN18.2 is prevalent11-14
  • Detecting CLDN18.2 can be accomplished by standard IHC staining methods, as with many other biomarkers11,12,14,15
Approximately 38% of cases demonstrated ≥75% of tumor cells with moderate-to-strong membranous CLDN18.2 staining
According to 2 recent studies in patients with advanced G/GEJ cancer:

No clear differences have been observed in the prevalence of select biomarkers with respect to CLDN18.2 expression, including1,16:

  • HER2
  • PD-L1
  • dMMR
Despite recent treatment advances, there are still critical needs to address17
  • Only approximately 5-10% of patients diagnosed with metastatic G/GEJ cancer  survive more than 5 years17,18*
  • In 2021, 2842 new cases of gastric cancer were diagnosed in the Nordic countries18

*The overall global 5-year survival rate for patients diagnosed with stage III G/GEJ is 10% and for stages IV patients 5%.17,18

Locally advanced (stage II and III) and metastatic (stage IV) G/GEJ cancer per TNM staging classification as described in NCCN Guidelines.19,20

CLDN18.1, claudin 18 isoform 1; CLDN18.2, claudin 18 isoform 2; dMMR, deficient mismatch repair; ESMO, European Society for Medical Oncology; GCs, gastric cancers; GECs, gastroesophageal cancers; G/GEJ, gastric/gastroesophageal junction; HER2, human epidermal growth factor receptor-2; IHC, immunohistochemistry; PD-L1, programmed death ligand 1; TNM, tumour node metastases.

Data from 2 single-institution studies. The first study was undertaken in Padua, Italy and included a large series of advanced GCs (n=280) and GECs (n=70).1 The second study was undertaken in 408 Japanese patients with advanced G/GEJ cancers.16

 

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CLDN18.2 expression profile is similar across multiple histopathological parameters21

  • Between resection (37.6%) and biopsy (38.6%) samples of G/GEJ cancer21
  • In gastric (39.9%) vs gastroesophageal junction (GEJ) (37.5%) cancer21
  • Between proximal (44%) and distal (5.3%) locations in G/GEJ cancer21
  • On archival and baseline (study screening) tissue in G/GEJ cancer*
    • Between samples collected at screening (archival) and baseline, 61.1% concordance of CLDN18.2 expression was observed21

*Times varied between collection of archival and baseline samples (21 to 1306 days).

RESECTION OF GASTRIC CANCER

2x magnification of CLDN18-stained normal gastric epithelium and tumour cells.

2x magnification of CLDN18-stained normal gastric epithelium and tumour cells.

BIOPSY OF GASTRIC CANCER

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5x magnification of CLDN18-stained tumour sample with surrounding normal gastric glands.

 

 

 

 

CLDN18.2 is expressed consistently making it a reliable biomarker for G/GEJ cancer.9

High-level concordance between primary and metastatic samples9

Data in patients with G/GEJ cancers suggest that CLDN18.2 expression demonstrated high concordance between primary and metastatic tumour samples.9

In a study of 523 primary G/GEJ adenocarcinomas and 135 pair-matched, synchronous modal metastases9:

86.7%
membranous staining concordance between matched primary and metastatic samples9
CLDN18.2 expression demonstrates intratumoural heterogeneity9

As is the case with other biomarkers such as HER2, CLDN18.2 expression may demonstrate variability within a tumour, and this should be taken into account when sampling.9,22

In the same study that demonstrated high-level concordance between primary and metastatic samples, intratumoural heterogeneity in terms of CLDN18.2 expression was found in9:

  • 40.3%

    of primary GC tumours

  • 33.6%

    of primary GEC tumours

  • 28.8%

    of nodal metastases



CLDN, claudin; CLDN18.2, claudin 18 isoform 2; GC, gastric cancer; GEC, gastroesophageal cancer; G/GEJ, gastric/gastroesophageal junction; HER2, human epidermal growth factor receptor-2; IHC, immunohistochemistry; TMA, tissue microarray.

MatteoFassan
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Learn more about sample preparation and testing

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References: 1. Pellino A, Brignola S, Riello E, et al. Association of CLDN18 protein expression with clinicopathological features and prognosis in advanced gastric and gastroesophageal junction adenocarcinomas. J Pers Med 2021;11(11):1095. 2. Tsukita S, Tanaka H, Tamura A. The claudins: from tight junctions to biological systems. Trends Biochem Sci 2019;44(2):141-52. 3. Hu YJ, Wang YD, Tan FQ, Yang WX. Regulation of paracellular permeability: factors and mechanisms. Mol Biol Rep 2013;40:6123-42. 4. Lordick F, Candia Montero L, Castelo-Branco L, et al. Ann Oncol 2022;33(10):1005-1020. ESMO Gastric Cancer Living Guideline.v1.2 ed October 2023. Available at https://www.esmo.org/living-guidelines/esmo-gastric-cancer-living-guideline. Accessed 03.05.2024. 5. Sahin U, Koslowski M, Dhaene K, et al. Claudin-18 splice variant 2 is a pan-cancer target suitable for therapeutic antibody development. Clin Cancer Res 2008;14(23):7624-34. 6. Niimi T, Nagashima K, Ward JM, et al. Claudin-18, a novel downstream target gene for the T/EBP/NKX2.1 homeodomain transcription factor, encodes lung- and stomach-specific isoforms through alternative splicing. Mol Cell Biol 2001;21(21):7380-90. 7. Sahin U, Schuler M, Richly H, et al. A phase I dose-escalation study of IMAB362 (Zolbetuximab) in patients with advanced gastric and gastro-oesophageal junction cancer. Eur J Cancer 2018;100:17-26. 8. Lamouille S, Xu J, Derynck R. Molecular mechanisms of epithelial-mesenchymal transition. Nat Rev Mol Cell Biol 2014;15(3):178–96. 9. Coati I, Lotz G, Fanelli GN, et al. Claudin-18 expression in oesophagogastric adenocarcinomas: a tissue microarray study of 523 molecularly profiled cases. Br J Cancer 2019;121(3):257-63. 10. Rohde C, Yamaguchi R, Mukhina S, Sahin U, Itoh K, Türeci O. Comparison of claudin 18.2 expression in primary tumors and lymph node metastases in Japanese patients with gastric adenocarcinoma. Jpn J Clin Oncol 2019;49(9):870-6. 11. Shitara K, Lordick F, Bang YJ, et al. Zolbetuximab plus mFOLFOX6 in patients with CLDN18.2-positive, HER2-negative, untreated, locally advanced unresectable or metastatic gastric or gastro-oesophageal junction adenocarcinoma (SPOTLIGHT): a multicentre, randomised, double-blind, phase 3 trial. Lancet 2023;401(10389):1655-68. 12. Shah MA, Shitara K, Ajani JA, et al. Zolbetuximab plus CAPOX in CLDN18.2-positive gastric or gastroesophageal junction adenocarcinoma: the randomized, phase 3 GLOW trial. Nat Med. 2023;29(8): 2133-2141. 13. Van Cutsem E, Bang YJ, Feng-yi F, et al. HER 2 screening data from ToGA: targeting HER2 in gastric and gastroesophageal junction cancer. Gastric Cancer 2015;18:476-84. 14. Fuchs Cs, Ozguroglu M, Bang YJ, et al. Pembrolizumab versus paclitaxel for previously treated PD-L1-positive advanced gastric or gastroesophageal junction cancer: 2-year update of the randomized phase 3 KEYNOTE-061 trial. Gastric Cancer 2022;25:197-206. 15. Abrahao-Machado LF, Scapulatempo-Neto C. HER2 testing in gastric cancer: an update. World J Gastroenterol 2016;22(19):4619-25. 16. Kubota Y, Kawazoe A, Mishima S, et al. Comprehensive clinical and molecular characterization of claudin 18.2 expression in advanced gastric or gastroesophageal junction cancer. ESMO Open 2023;8(1):100762. 17. Casamayor M, Morlock R, Maeda H, Ajani J. Targeted literature review of the global burden of gastric cancer. Ecancermedicalscience 2018;12:883. eCollection 2018. 18. Larønningen S, Ferlay J, Beydogan H, et al (2022). NORDCAN: Cancer Incidence, Mortality, Prevalence and Survival in the Nordic Countries, Version 9.2 (23.06.2022). Association of the Nordic Cancer Registries. Cancer Registry of Norway. Available from: https://nordcan.iarc.fr/en/dataviz/survival_table?sexes=2. Accessed 03.05.2024. 19. Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Gastric Cancer V.1.2023. National Comprehensive Cancer Network, Inc. 2023. All rights reserved. Accessed 03.05.2024. To view the most recent and complete version of the guideline, go online to NCCN.org. 20. Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Esophageal and Esophagogastric Junction Cancers V.2.2023. National Comprehensive Cancer Network, Inc. 2023. All rights reserved. To view the most recent and complete version of the guideline, go online to NCCN.org. Accessed 03.05.2024. 21. Shitara K, Xu R, Moran D, et al. Global prevalence of CLDN18.2 in patients with locally advanced (LA) unresectable or metastatic gastric or gastroesophageal junction (mG/GEJ) adenocarcinoma: Biomarker analysis of two zolbetuximab phase 3 studies (SPOTLIGHT and GLOW). Presented at the 2023 ASCO Annual Meeting; June 2-6, 2023; Chicago, IL, USA.  22. Cao W, Xing H, Li Y, et al. Claudin18.2 is a novel molecular biomarker for tumor‑targeted immunotherapy. Biomarker Research 2022;10:38. 23. Grillo F, Fassan M, Sarocchi F, et al. HER2 heterogeneity in gastric/gastroesophageal cancers: from benchside to practice. World J Gastroenterol 2016;22(26):5879-87.