BACKGROUND: Peritumoral brain edema (PTBE) has been widely reported with many brain tumors, especially with glioma. Since the blood-brain barrier (BBB) is essential for maintaining minimal permeability, any alteration in the interaction of BBB components, specifically in astrocytes and tight junctions (TJ), can result in disrupting the homeostasis of the BBB and making it severely leaky, which subsequently generates edema.
OBJECTIVE: This study aimed to evaluate the functional gliovascular unit of the BBB by examining changes in the expression of claudin (CLDN) genes and the expression of transient receptor potential (TRP) membrane channels, additionally to define the correlation between their expressions. The evaluation was conducted using in vitro spheroid swelling models and tumor samples from glioma patients with PTBE.
RESULTS: The results of the spheroid model showed that the genes TRPC3, TRPC4, TRPC5, and TRPV1 were upregulated in glioma cells either wild-type isocitrate dehydrogenase 1 (IDH1) or the IDH1 R132H mutant, with or without NaCl treatment. Furthermore, TRP genes appeared to adversely correlate with the up regulation of CLDN1, CLDN3, and CLDN5 genes. Besides, the upregulation of TRPC1 and TRPC4 in IDH1mt-R132H glioma cells. On the other hand, the correlation analysis revealed different correlations between different proteins in PTBE. CLDN1 exhibits a slight positive correlation with CLDN3. Similarly, TRPV1 displays a slight positive correlation with TRPC1. In contrast, TRPC4 shows a slight negative correlation with TRPC5. On the other hand, TRPC3 demonstrates a slight positive correlation with TRPC5, while the non-PTBE analysis highlights a moderate positive correlation between CLDN1 and TRPM4 while CLDN3 exhibits a moderate negative correlation with TRPC4. Additionally, CLDN5 demonstrates a slight negative correlation with TRPC4 but a moderate positive correlation with TRPC3. Furthermore, TRPC1 have a slight negative correlation with TRPV1, TRPC3 exhibiting a slight positive correlation with TRPC4, and TRPV1 showing a slight negative correlation with TRPC5.
CONCLUSIONS: As a conclusion, the current study provided evidence of a slight negative correlation between TRPs and CLDN gene expression in PTBE patients and confirmatory results with some of the genes in cell model of edema.

Multiple classes of therapies targeting claudin-18 isoform 2 (CLDN18.2) are under development for the treatment of advanced gastroesophageal adenocarcinoma and other solid tumors. At the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting, the final results of the phase 3 SPOTLIGHT trial were presented, demonstrating a significant survival benefit from the addition of the CLDN18.2-specific antibody zolbetuximab to chemotherapy in the first-line treatment of advanced gastroesophageal adenocarcinomas with ≥ 75% CLDN18.2 expression. Early-phase trial results presented at ASCO 2024 showed promising efficacy and safety of the afucosylated CLDN18.2-specific antibody FG-M108 in combination with chemotherapy in the first-line treatment of CLDN18.2-positive advanced gastroesophageal and pancreatic cancers. In addition, several early-phase trials presented at ASCO 2024 investigate other CLDN18.2-targeting approaches in CLDN18.2-positive refractory advanced solid tumors, including the CLDN18.2-targeting antibody-drug conjugates LM-302 and IBI343, the bispecific anti-CLDN18.2/CD3 antibody IBI38, and the chimeric antigen receptor T cell therapy satricabtagene autoleucel. These novel approaches could potentially expand the benefit of CLDN18.2-targeting therapies to a broader range of tumor types and to tumors expressing lower levels of CLDN18.2.

Objective To screen a monoclonal antibody (mAb) of anti-human Claudin-18 splice variant 2 (Claudin18.2) and construct chimeric antigen receptor T (CAR-T) cells targeting Claudin18.2 based on this antibody sequence for the development of CAR-T cell therapy. Methods Mice were immunized with human Claudin18.2 antigen, and then mice spleen cells were isolated and fused with SP2/0 cells to generate hybridoma cells. By hybridoma screening, we obtained the mouse against human Claudin18.2 mAb. The heavy chain variable region (VH) and light chain variable region (VL) sequences were amplified by PCR with the antibody sequence serving as the template. The linker peptide was used to link VL and VH into a single chain antibody (scFv) for CAR construction. The CAR was cloned into a lentiviral expression vector, and T cells were infected with the packaged lentivirus to prepare targeting Claudin18.2 CAR-T cells. Results The screened mouse anti-human Claudin18.2 mAb exhibited binding ability to both human and mouse Claudin18.2 antigens, with higher affinity than the control antibody. The constructed CAR-T cells showed a killing rate between 50% to 70% against Claudin18.2-overexpressing positive target cells at an effector-to-target ratio of 1:9. Conclusion The prepared mouse anti-human Claudin18.2 mAb exhibites cross-species specificity to humans and mice antigens, with good tissue specificity and high affinity. The constructed anti-Claudin18.2 CAR-T cells show effective killing of target cells.

Cadherin 17 (CDH17) and claudin 18.2 (CLDN18.2) are highly selective markers of intestinal and gastric lineages and are expressed in adenocarcinomas of various organs. They have also been identified as potential targets for immunotherapy. Expression of CDH17 and CLDN18.2 has been observed in a subset of pancreatic neuroendocrine tumours (PanNETs). This study investigates the immunohistochemical expression of CDH17 and CLDN18 in PanNETs in comparison with hormonal expression profiles to provide baseline data for determining candidate indications for targeted therapy with CDH17 and CLDN18.2 in PanNETs, including insulinomas (n = 22), glucagonomas (n = 13), gastrinomas (n = 3), serotoninomas (n = 2) and PanNETs not otherwise specified (NOS) (n = 17). In the normal pancreas, CDH17 was expressed in the lateral membrane of ducts and some islet cells, whereas CLDN18 was occasionally expressed in the intercalated ducts and centroacinar cells. In PanNETs, CDH17 and CLDN18 was detected by membranous staining. CDH17 expression was observed in 10 to 17 (58.8 %) PanNETs NOS, 3 of 13 (23.1 %) glucagonomas, 1 of 3 (33.3 %,) gastrinomas, 1 of 2 (50 %) serotoninomas, and none of the insulinomas. According to predefined criteria, 7 of 17 (41.2 %) PanNETs NOS, 1 of 3 (33.3 %) gastrinomas, and 1 of 2 (50 %) serotoninomas were classified as CDH17-positive. There were no significant differences in clinicopathological features between CDH17-positive and CDH17-negative PanNETs, except for a higher tumour grade in the former (p<0.05). For CLDN18, expression was noted in 2 out of 3 (66.7 %) gastrinomas, one with focal staining and the other with diffuse staining. One of three (33.3 %) gastrinomas was classified as CLDN18-positive using predefined criteria. These findings suggest that a particular subset of PanNETs, including PanNET NOS, gastrinoma, and serotoninoma, may be potential candidates for CDH17-targeted immunotherapy. Additionally, gastrinoma may be a potential candidate for immunotherapy targeting CLDN18.2.

BACKGROUND: CLDN is a core component of tight junctions (TJs). Abnormal expressions of CLDNs are commonly detected in various types of tumors. CLDNs are of interest as a potential therapeutic target. CLDNs are closely associated with most cancers of epithelial origin, especially when CLDN7 promotes cancer cell metastasis, such as in gastric, cervical, and ovarian cancers.Its expression and prognosis in breast cancer (BC) remain unknown.The purpose of this study was to investigate the expression pattern of CLDN7 and related immune factors in BC and shed light on a better therapeutic avenue for BC patients.
METHODS: The cBioPortal, GEPIA, and TCGA databases were used to comprehensively assess the expression of CLDN7 in BC. The Kaplan-Meier Plotter (KMP) database was applied to examine the relationship among the CLDN7 overexpression (OE), prognosis, and overall survival (OS) of BC patients. Immunohistochemical staining was performed on 92 BC tissue samples and 20 benign breast tumors to verify the expression level of CLDN-7 protein and its correlation with clinicopathological features and prognosis. TIMER2.0 was used to analyze the correlation between the CLDN7 OE and immune gene activation using BC-related transcriptomic data. Enrichment analyses of CLDN7-related immune pathways were conducted using online databases. The risk of expression of CLDN7-related immune genes was assessed and differentially expressed (DE) genes were included in the construction of the risk prognosis nomogram.
RESULTS: Both database analysis and clinical sample validation results showed that CLDN7 was significantly overexpressed (OE) in BC, and the OE was correlated with poor DFS in BC patients (p < 0.05). TIMER2.0 analysis indicated that CLDN7 OE was negatively associated with the activation of B-cells, CD4+ T-cells, and CD8+ T-cells but positively with the M0 macrophages. Pathway enrichment analysis suggested that CLDN7-related immune factors were mostly involved in the NF-κB and T-cell receptor (TCR) signaling pathways. Univariate Cox regression was used to analyze the correlation between 52 CLDN7 related genes and OS, and 22 genes that are related to prognosis were identified. Prognostic genes were included in the prognostic nomogram of BC with a C-index of 0.76 to predict the 3-year and 5-year OS probabilities of BC individuals.
CONCLUSIONS: These findings provide evidence for the role of CLDN7-linked tumor immunity, suggesting that CLDN7 might be a potential immunotherapeutic target for BC, and its association with immune markers could shed light on the better prognosis of BC.

BACKGROUND: Breast cancer (BC) ranks as the third most fatal malignant tumor worldwide, with a strong reliance on fatty acid metabolism. CLDN6, a candidate BC suppressor gene, was previously identified as a regulator of fatty acid biosynthesis; however, the underlying mechanism remains elusive. In this research, we aim to clarify the specific mechanism through which CLDN6 modulates fatty acid anabolism and its impact on BC growth and metastasis.
METHODS: Cell function assays, tumor xenograft mouse models, and lung metastasis mouse models were conducted to evaluate BC growth and metastasis. Human palmitic acid assay, triglyceride assay, Nile red staining, and oil red O staining were employed to investigate fatty acid anabolism. Reverse transcription polymerase chain reaction (RT-PCR), western blot, immunohistochemistry (IHC) assay, nuclear fractionation, immunofluorescence (IF), immunoprecipitation and acyl-biotin exchange (IP-ABE), chromatin immunoprecipitation (ChIP), dual luciferase reporter assay, and co-immunoprecipitation (Co-IP) were applied to elucidate the underlying molecular mechanism. Moreover, tissue microarrays of BC were analyzed to explore the clinical implications.
RESULTS: We identified that CLDN6 inhibited BC growth and metastasis by impeding RAS palmitoylation both in vitro and in vivo. We proposed a unique theory suggesting that CLDN6 suppressed RAS palmitoylation through SREBP1-modulated de novo palmitic acid synthesis. Mechanistically, CLDN6 interacted with MAGI2 to prevent KLF5 from entering the nucleus, thereby restraining SREBF1 transcription. The downregulation of SREBP1 reduced de novo palmitic acid synthesis, hindering RAS palmitoylation and subsequent endosomal sorting complex required for transport (ESCRT)-mediated plasma membrane localization required for RAS oncogenic activation. Besides, targeting inhibition of RAS palmitoylation synergized with CLDN6 to repress BC progression.
CONCLUSIONS: Our findings provide compelling evidence that CLDN6 suppresses the palmitic acid-induced RAS palmitoylation through the MAGI2/KLF5/SREBP1 axis, thereby impeding BC malignant progression. These results propose a new insight that monitoring CLDN6 expression alongside targeting inhibition of palmitic acid-mediated palmitoylation could be a viable strategy for treating oncogenic RAS-driven BC.

Breast cancer is the most common cause of death from cancer in women. Here, we present the case of a 43-year-old woman, who received a diagnosis of claudin-low luminal B breast cancer. The lesion revealed to be a poorly differentiated high-grade infiltrating ductal carcinoma, which was strongly estrogen receptor (ER)/progesterone receptor (PR) positive and human epidermal growth factor receptor (HER2) negative. Her tumor underwent in-depth chromosomal, mutational and gene expression analyses. We found a pathogenic protein truncating mutation in the TP53 gene, which is predicted to disrupt its transcriptional activity. The patient also harbors germline mutations in some mismatch repair (MMR) genes, and her tumor displays the presence of immune infiltrates, high tumor mutational burden (TMB) status and the apolipoprotein B mRNA editing enzyme catalytic polypeptide 3 (APOBEC3) associated signatures, which, overall, are predictive for the use of immunotherapy. Here, we propose promising prognostic indicators as well as potential therapeutic strategies based on the molecular characterization of the tumor.

BACKGROUND: First-line zolbetuximab plus chemotherapy (SPOTLIGHT, mFOLFOX6; GLOW, CAPOX) significantly improved progression-free survival (PFS) and overall survival (OS) versus placebo plus chemotherapy in patients with human epidermal growth factor receptor 2-negative, locally advanced unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma whose tumors were claudin 18 isoform 2-positive in the phase III SPOTLIGHT (NCT03504397) and GLOW (NCT03653507) studies. We present patient-reported outcomes (PROs) from these studies.
METHODS: Health-related quality of life (HRQoL) was measured in the full analysis sets using the European Organisation for Research and Treatment of Cancer Quality of Life of Cancer Patients Core Questionnaire (QLQ-C30) and Oesophago-Gastric Module (QLQ-OG25), Global Pain, and 5-level EQ-5D (EQ-5D-5L) questionnaires. Analyses focused on key PRO domains: global health status (GHS)/QoL, physical functioning, abdominal pain and discomfort, and nausea/vomiting. Least squares mean (LSM) changes from baseline and time to first definitive deterioration (TTDD) were evaluated combined across SPOTLIGHT and GLOW and for individual studies. Time to confirmed deterioration (TTCD) was evaluated independently for SPOTLIGHT and GLOW.
RESULTS: The combined analysis set included 1072 patients (zolbetuximab plus chemotherapy, 537; placebo plus chemotherapy, 535). Compliance rates were similar between treatment arms. Similar trends were observed in the zolbetuximab versus placebo arms for LSM changes from baseline in key PRO domains, with no clinically meaningful deterioration. Nausea/vomiting worsened during the first few zolbetuximab cycles but later returned to baseline levels. Overall TTCD and TTDD results were similar between arms in both studies.
CONCLUSIONS: Patients in SPOTLIGHT and GLOW maintained measured HRQoL relative to baseline when treated with first-line zolbetuximab added to chemotherapy. Zolbetuximab plus chemotherapy improved PFS and OS without negatively affecting HRQoL in key PRO domains compared with placebo plus chemotherapy.

Activating antibody-dependent cellular cytotoxicity (ADCC) by targeting claudin-18 isoform 2 (CLDN18.2) using zolbetuximab, a monoclonal antibody against CLDN18.2, has been considered a promising novel therapeutic strategy for gastric cancer (GC). However, the impact of CLDN18.2 expression on natural killer (NK) cells and monocytes/macrophages-crucial effector cells of ADCC-in GC has not been fully investigated. In the present study, we assessed the impact of CLDN18.2 expression on clinical outcomes, molecular features, and the frequencies of tumor-infiltrating NK cells and macrophages, as well as peripheral blood NK cells and monocytes, in GC by analyzing our own GC cohorts. The expression of CLDN18.2 did not significantly impact clinical outcomes of GC patients, while it was significantly and positively associated with Epstein-Barr virus (EBV) status and PD-L1 expression. The frequencies of tumor-infiltrating NK cells and macrophages, as well as peripheral blood NK cells and monocytes, were comparable between CLDN18.2-positive and CLDN18.2-negative GCs. Importantly, both CLDN18.2 expression and the number of tumor-infiltrating NK cells were significantly higher in EBV-associated GC compared to other molecular subtypes. Our findings support the effectiveness of zolbetuximab in CLDN18.2-positive GC, and offer a novel insight into the treatment of this cancer type, highlighting its potential effectiveness for CLDN18.2-positive/EBV-associated GC.

Claudin 18.2 has emerged as a viable therapeutic target in gastric cancer (GC), but little is known about the heterogeneity of its expression in GC. This study investigated the heterogeneity of claudin 18.2 expression in 166 patients with metastatic GC whose surgical or paired primary-metastatic specimens were available. The prevalence of claudin 18.2 positivity (moderate-to-strong expression in ≥ 75% by the 43-14A clone) was 47.0%. Claudin 18.2-positive tumors exhibited more frequent peritoneal metastasis and a lower incidence of hepatic and distant lymph node involvement. Survival outcomes were comparable between patients with claudin 18.2-positive and -negative tumors. Intratumoral heterogeneity was noted in 38.5% of surgical specimens. Paired primary-metastatic site analysis revealed that 25.2% of patients had discordant results for claudin 18.2 positivity. Across different metastatic organ categories, peritoneal lesions showed the highest positivity rate (44.3%) and positive concordance rate (31.4%), whereas liver lesions had the lowest positivity rate (17.9%) and concordance rate (12.8%). In conclusion, claudin 18.2 expression exhibits intratumoral and intrapatient spatial heterogeneity in metastatic GC. Claudin 18.2 positivity is associated with more frequent peritoneal metastasis, and peritoneal lesions are more likely to have positively concordant claudin 18.2 results with the primary site than other metastatic sites.