Claudin18.2 expression and clinicopathological features in cytology effusion specimens from gastric adenocarcinoma: A comparative study with tissue specimens

The value of serum tumor-associated autoantibodies in screening and diagnosis of gastric cancer

OBJECTIVE

To investigate the clinical value of serum autoantibodies in the screening and diagnosis of gastric cancer.

MATERIALS & METHODS

A total of 570 gastric cancer patients and 373 controls were enrolled in this study. Enzyme-linked immunosorbent assay (ELISA) was employed to quantitatively detect autoantibodies in the tested serum, and statistic modeling was conducted to analyze their relationships with various clinical and pathological parameters.

RESULTS

The results of autoantibody detection in gastric cancer patients were significantly different from those of the control group. A combination of 7 autoantibodies, including CLDN18, CAGE1, CTAG1A, PBRM1, RASSF7, IMMP2L and COPB1, was selected for modeling (AUC = 0.885). The diagnostic specificity was approximately 0.86 when combined 7-TAAs with Helicobacter pylori, while the positive predictive value was increased to 0.94. The abnormal elevation of different TAAs proteins in gastric cancer patients is related to factors such as disease stage, tumor differentiation degree, and invasion depth.

CONCLUSION

The determination of serum autoantibody panel has clinical value in screening and prediction of gastric cancer, and can be used as an auxiliary index in clinical diagnosis. The combination of 7-TAAs and Helicobacter pylori can effectively improve the screening specificity and positive predictive value. The detection results of different proteins were related to the stage of disease, the degree of tumor differentiation and the depth of invasion.

Claudin 18.2 Expression in 1404 Digestive Tract Adenocarcinomas Including 1175 Colorectal Carcinomas: Distinct Colorectal Carcinoma Subtypes Are Claudin 18.2 Positive

Claudin 18.2 (CLDN18.2) immunohistochemical (IHC) expression can be used to select patients with gastric/gastroesophageal junction adenocarcinomas for zolbetuximab (IMAB362) therapy, zolbetuximab (IMAB362) being a monoclonal antibody targeting CLDN18.2. The aim of this study was to correlate IHC expression of CLDN18.2 with clinicopathologic and molecular features in a large series of digestive tract cancers. IHC for CLDN18.2 was performed on tissue microarrays from 1404 adenocarcinomas including 155 gastric/gastroesophageal, 74 pancreatic ductal, and 1175 colorectal (576 in the initial test cohort; 599 in the subsequent validation cohort), and correlated with HER2 and mismatch repair (MMR) status. Cases were scored as CLDN18.2 positive or negative, with positivity defined as moderate-to-strong membranous staining in ≥75% of tumor cells. CLDN18.2 expression was correlated with clinicopathologic and molecular features for all colorectal adenocarcinomas. CLDN18.2 was positive in 39% (61/155) of gastric/gastroesophageal adenocarcinomas, 38% (28/74) of pancreatic ductal adenocarcinomas, and 3.4% (40/1175) of colorectal adenocarcinomas (P < .001). For gastric/gastroesophageal and pancreatic ductal adenocarcinoma, there was no correlation between CLDN18.2 expression and either HER2 or MMR status. In contrast, CLDN18.2-positive colorectal adenocarcinomas had distinct clinicopathologic and molecular features. CLDN18.2-positive colorectal adenocarcinomas were more frequently proximally located and were more often MMR deficient and BRAF V600E positive (all with P < .05). Quantitative pathologic analysis using the digital pathology biomarker QuantCRC (Aiforia) demonstrated marked differences in histologic features between CLDN18.2-positive and CLDN18.2-negative colorectal adenocarcinomas, with CLDN18.2-positive tumors having an increased tumor:stroma ratio and %mucin but decreased %immature stroma in both the test and validation cohorts (all with P < .05). In conclusion, CLDN18.2-positive colorectal adenocarcinomas are frequently MMR deficient and BRAF V600E mutated, and demonstrate distinct histologic features. Future studies addressing the efficacy of zolbetuximab therapy in this subset of colorectal cancers are needed.

Emerging Claudin18.2-targeting Therapy for Systemic Treatment of Gastric Cancer: Seeking Nobility Amidst Danger

Gastric cancer in advanced stages lacked effective treatment options. claudin18.2 (CLDN18.2) is a membrane protein that is crucial for close junctions in the differentiated epithelial cells of the gastric mucosa, playing a vital role in barrier function, and can be hardly recognized by immune cells due to its polarity pattern. As the polarity of gastric tumor cells changes, claudin18.2 is exposed on the cell surface, resulting in immune system recognition, and making it an ideal target. In this review, we summarized the expression regulation mechanism of claudin18.2 both in normal cells and malignant tumor cells. Besides, we analyzed the available clinical results and potential areas for future research on claudin18.2-positive gastric cancer and claudin18.2-targeting therapy. In conclusion, claudin18.2 is an ideal target for gastric cancer treatment, and the claudin18.2-targeting therapy has changed the treatment pattern of gastric cancer.

Canadian Consensus Recommendations for Predictive Biomarker Testing in Gastric and Gastroesophageal Junction Adenocarcinoma

Gastric cancer is common globally and has a generally poor prognosis with a low 5-year survival rate. Targeted therapies and immunotherapies have improved the treatment landscape, providing more options for efficacious treatment. The use of these therapies requires predictive biomarker testing to identify patients who can benefit from their use. New therapies on the horizon, such as CLDN18.2 monoclonal antibody therapy, require laboratories to implement new biomarker tests. A multidisciplinary pan-Canadian expert working group was convened to develop guidance for pathologists and oncologists on the implementation of CLDN18.2 IHC testing for gastric and gastroesophageal junction (G/GEJ) adenocarcinoma in Canada, as well as general recommendations to optimize predictive biomarker testing in G/GEJ adenocarcinoma. The expert working group recommendations highlight the importance of reflex testing for HER2, MMR and/or MSI, CLDN18, and PD-L1 in all patients at first diagnosis of G/GEJ adenocarcinoma. Testing for NTRK fusions may also be included in reflex testing or requested by the treating clinician when third-line therapy is being considered. The expert working group also made recommendations for pre-analytic, analytic, and post-analytic considerations for predictive biomarker testing in G/GEJ adenocarcinoma. Implementation of these recommendations will provide medical oncologists with accurate, timely biomarker results to use for treatment decision-making.

The role of CLDN18.2 in gastric cancer prognosis: a systematic review and meta-analysis

BACKGROUND

Gastric cancer (GC) is a major global cause of cancer mortality, with a median overall survival of just 12 months. CLDN18.2, a specific isoform of Claudin18 normally expressed in the gastric mucosa, has emerged as a potential therapeutic target and prognostic biomarker due to its exposure on the surface of tumor cells following malignant transformation. This exposure allows CLDN18.2's extracellular loops to bind monoclonal antibodies, presenting new opportunities for targeted therapy and improved prognostic assessment.

METHODS

A comprehensive search of PubMed, EMBASE, Cochrane Library, and Web of Science databases was conducted for studies that addressed the correlation of CLDN18.2 with: (1) Progression-free survival (PFS) and (2) Overall Survival (OS). Hazard ratio (HR) and odds ratio (OR) with 95% confidence intervals (CIs) were calculated using a fixed-effects model. Heterogeneity was examined with I2 statistics. P values of ≤ 0.05 were considered statistically significant. Statistical analyses were performed using RStudio, version 4.2.3.

RESULTS

A total of 15 studies encompassing a total of 4,085 patients were included. There were 2,691 (65.8%) male and 1,394 (34.2%) female patients. In the histologic GC analysis, there were 1,582 (38.7%) patients that had intestinal type and 1,280 (31.3%) with diffuse type. Patients with CLDN18.2 negative status exhibited a non-significant trend towards prolonged PFS (HR: 1.25; 95% CI: 0.98-1.61; p = 0.07; I2 = 18%) and a significant prolonged OS (HR: 1.20; 95% CI: 1.07-1.34; p < 0.01; I2 = 37%) when compared to CLDN18.2-positive patients.

CONCLUSION

Our findings establish CLDN18.2 as a robust negative prognostic indicator for overall survival in GC patients. While its impact on PFS was not statistically significant, the association with OS suggests CLDN18.2 may serve as a marker for complex biological processes underlying tumor advancement.

Claudin-18.2 Immunohistochemical Evaluation in Gastric and Gastroesophageal Junction Adenocarcinomas to Direct Targeted Therapy: A Practical Approach

Claudin-18.2 (CLDN18.2) expression evaluated by immunohistochemistry is a new biomarker for gastric and gastroesophageal junction adenocarcinomas that will soon have market authorization for implementation into routine clinical practice. Despite successful testing in the setting of clinical trials, no specific practical testing guidelines have been proposed. Several preanalytical and analytical variables may interfere with adequate CLDN18.2 staining interpretation; thus, this article provides practical guidance on CLDN18.2 testing and scoring in gastric and gastroesophageal junction adenocarcinomas to identify patients who may respond to targeted therapy with monoclonal antibodies directed against CLDN18.2. Based on available data, moderate to strong (2+/3+) membrane staining in ≥75% of adenocarcinoma cells is the proposed cutoff for clinical use of monoclonal antibody anti-CLDN18.2 (zolbetuximab).

Claudin18.2-Targeted SPECT/CT Imaging for Gastric Cancer: Preclinical Evaluation and Clinical Translation of the 99mTc-Labeled Nanobody (PHG102) Radiotracer

Claudin18.2 (CLDN18.2) has emerged as a significant target in the treatment of advanced gastric cancer. The screening of patients positive for CLDN18.2 is crucial for the effective application of targeted therapies specific to CLND18.2. In this study, we developed a novel nanobody-based probe, [99mTc]Tc-PHG102, for use in nuclear medicine. We analyzed its radiochemical yield and stability to ensure accurate probe characterization. Additionally, we assessed the probe's affinity and specificity toward the CLDN18.2 target and evaluated its efficacy in the BGC82318.2 xenograft model for SPECT/CT imaging of gastric cancer. The binding of [99mTc]Tc-PHG102 to HEK-293T18.2 and BGC82318.2 cells was notably higher than its binding to HEK-293T18.1, HEK-293T, and BGC823 cells, with bound values of 12.87 ± 1.46%, 6.16 ± 0.34%, 1.25 ± 0.22%, 1.14 ± 0.26%, and 1.32 ± 0.07% AD, respectively. The binding ability of [99mTc]Tc-PHG102 was significantly different between CLDN18.2-positive and negative cells (P < 0.001). Imaging results demonstrated a time-dependent tumor accumulation of the radiotracer. Notably, at 0.5 h postinjection, rapid accumulation was observed with an average tumor uptake of 4.63 ± 0.81% ID/cc (n = 3), resulting in clear tumor visualization. By 1 h postinjection, as [99mTc]Tc-PHG102 was rapidly metabolized, a decrease in uptake by other organs was noted. Preliminary clinical imaging trials further confirmed the safety and effectiveness of the probe, indicating specificity for lesions expressing CLDN18.2 in gastric cancer and favorable in vivo metabolic properties. In conclusion, the nanobody-based probe [99mTc]Tc-PHG102 proves to be a safe and effective tool for detecting CLDN18.2 expression levels in gastric cancer tumors and for screening CLDN18.2-positive patients.

Claudin-18 status and its correlation with HER2 and PD-L1 expression in gastric cancer with peritoneal dissemination

BACKGROUND

Gastric cancer with peritoneal dissemination (PD) has a dismal prognosis, and current treatments have shown little efficacy. CLDN18.2-targeted therapies have shown promising efficacy against gastric cancers that express high levels of CLDN18. Because of the limited information regarding CLDN18.2 status in PD, we analyzed PD-positive gastric cancers for CLDN18 status in both primary and PD, along with HER2 and PD-L1 combined positive score (CPS).

METHODS

Immunohistochemical analyses were performed on 84 gastric cancer cases using paired primary and PD tissue samples.

RESULTS

At 40% cut-off, CLDN18 was positive in 57% (48/84) primary tumors and in 44% (37/84) PDs. At 75% cut-off, 28.6% (24/84) primary tumors and 20.2% (17/84) PDs were CLDN18-positive. The concordance rate between primary tumors and PD was 79.8% at 40% cut-off and 75% at 75% cut-off. When comparing biopsy and surgical specimens, the concordance rates were 87.5% at 40% cut-off and 81.3% at 75% cut-off. Within a tumor, the superficial area tended to have a higher CLDN18-positive rate than the invasive front (P = 0.001). Although HER2 -positivity was only 11.9% in this cohort, CLDN18 positivity in HER2-negative tumors (n = 74) was relatively high: 60.8% at 40% cut-off and 28.4% at 75% cut-off. Among double-negative (HER2 - and PD-L1 CPS < 1) tumors, CLDN18 positivity was 67.6% at 40% cut-off and 26.5% at 75% cut-off.

CONCLUSIONS

CLDN18 expression is generally maintained in PD and is relatively high even in double-negative tumors, making it a promising therapeutic target for PD-positive gastric cancer.

68Ga-NC-BCH Whole-Body PET Imaging Rapidly Targets Claudin18.2 in Lesions in Gastrointestinal Cancer Patients

68Ga-labeled nanobody (68Ga-NC-BCH) is a single-domain antibody-based PET imaging agent. We conducted a first-in-humans study of 68Ga-NC-BCH for PET to determine its in vivo biodistribution, metabolism, radiation dosimetry, safety, and potential for quantifying claudin-18 isoform 2 (CLDN18.2) expression in gastrointestinal cancer patients. Methods: Initially, we synthesized the probe 68Ga-NC-BCH and performed preclinical evaluations on human gastric adenocarcinoma cell lines and xenograft mouse models. Next, we performed a translational study with a pilot cohort of patients with advanced gastrointestinal cancer on a total-body PET/CT scanner. Radiopharmaceutical biodistribution, radiation dosimetry, and the relationship between tumor uptake and CLDN18.2 expression were evaluated. Results: 68Ga-NC-BCH was stably prepared and demonstrated good radiochemical properties. According to preclinical evaluation,68Ga-NC-BCH exhibited rapid blood clearance, high affinity for CLDN18.2, and high specific uptake in CLDN18.2-positive cells and xenograft mouse models. 68Ga-NC-BCH displayed high uptake in the stomach and kidney and slight uptake in the pancreas. Compared with 18F-FDG, 68Ga-NC-BCH showed significant differences in uptake in lesions with different levels of CLDN18.2 expression. Conclusion: A clear correlation was detected between PET SUV and CLDN18.2 expression, suggesting that 68Ga-NC-BCH PET could be used as a companion diagnostic tool for optimizing treatments that target CLDN18.2 in tumors.

Claudin-18.2 testing and its impact in the therapeutic management of patients with gastric and gastroesophageal adenocarcinomas: A literature review with expert opinion

Claudin-18.2 (CLDN18.2) is a member of the tight junction protein family and is a highly selective biomarker with frequent abnormal expression during the occurrence and development of various primary malignant tumors, including gastric cancer (GC) and esophago-gastric junction adenocarcinomas (EGJA). For these reasons, CLDN18.2 has been investigated as a therapeutic target for GC/EGJA malignancies. Recently, zolbetuximab has been proposed as a new standard of care for patients with CLDN18.2-positive, HER2-negative, locally advanced and metastatic GC/EGJA. The use of CLDN18 IHC assays to select patients who might benefit from anti-CLDN18.2 therapy is currently entering clinical practice. In this setting, pathologists play a central role in therapeutic decision-making. Accurate biomarker assessment is essential to ensure the best therapeutic option for patients. In the present review, we provide a comprehensive overview of available evidence on CLDN18.2 testing and its impact on the therapeutic management of patients with GC/EGJA, as well as some practical suggestions for CLDN18.2 staining interpretation and potential pitfalls in the real-world setting.

CLDN18.2 expression and its impact on prognosis and the immune microenvironment in gastric cancer

BACKGROUND

The investigational use of zolbetuximab (IMAB362), a groundbreaking monoclonal antibody medication targeting claudin 18.2 (CLDN18.2), for treatment of advanced gastrointestinal cancers is currently underway. The unclear clinicopathological characteristics and tumour immune microenvironment of CLDN18.2-positive gastric cancer (GC) make it difficult to develop and optimize CLDN18.2-targeted therapies.

METHODS

A total of 451 tumour tissues, 342 matched paraneoplastic tissues, and 107 matched metastatic lymph nodes were collected from GC patients. These specimens were stained for CLDN18.2 expression and quantified using immunohistochemistry (IHC). Correlations between CLDN18.2 expression and clinicopathological features as well as immune-related factors were analysed. Survival curves were drawn using the Kaplan‒Meier approach, and independent factors affecting GC prognosis were identified using Cox regression analysis. Information from relevant databases was used for corroboration.

RESULTS

Expression of the CLDN18.2 gene was significantly lower in gastric tumour tissues than in normal tissues (p < 0.001) but comparable in metastatic lymph nodes (p = 0.851). CLDN18.2 expression was significantly associated with Borrmann type, degree of differentiation, PD-L1 expression, and survival in GC patients and was identified as an independent risk factor for patient prognosis (HR = 1.57, 95% CI 1.16-2.11, p = 0.003). There was no correlation between CLDN18.2 expression and HER2, Lauren type, tumour size, TNM stage, or any other clinicopathological characteristic. In CLDN18.2-positive tumours, fractions of CD4 + T cells and CD8 + T cells were significantly higher than those in CLDN18.2-negative tumours. Patients with CLDN18.2-negative expression and significant CD4 + T-cell or CD8 + T-cell infiltration had the best prognosis (5-year OS: 61.0%, P = 0.036; 5-year OS: 62.2%, P = 0.034).

CONCLUSIONS

CLDN18.2 is expressed at a low level in tumour tissues and serves as an independent prognostic factor for patients with GC. Furthermore, CLDN18.2 correlates with immune infiltrating cells and PD-L1 expression.