Claudin-18 splice variant 2 is a pan-cancer target suitable for therapeutic antibody development

Programmable Chemical Evolution with Natural/Non-Natural Building Blocks

Non-natural building blocks (BBs) present a vast reservoir of chemical diversity for molecular recognition and drug discovery. However, leveraging evolutionary principles to efficiently generate bioactive molecules with a larger number of diverse BBs poses challenges within current laboratory evolution systems. Here, we introduce programmable chemical evolution (PCEvo) by integrating chemoinformatic classification and high-throughput array synthesis/screening. PCEvo initiates evolution by constructing a diversely combinatorial library to create ancestral molecules, streamlines the molecular evolution process and identifies high-affinity binders within 2-4 cycles. By employing PCEvo with 108 BBs and exploring >1017 chemical space, we identify bicyclic peptidomimetic binders against targets SAR-CoV-2 RBD and Claudin18.2, achieving nanomolar affinity. Remarkably, Claudin18.2 binders selectively stain gastric adenocarcinoma cell lines and patient samples. PCEvo achieves expedited evolution in a few rounds, marking a significant advance in utilizing non-natural building blocks for rapid chemical evolution applicable to targets with or without prior structural information and ligand preference.

Effect of antiemetics on zolbetuximab-induced gastric injury and emesis in ferrets

Claudin-18 splice variant 2 (CLDN18.2), a tight junction protein, is a highly cell type-specific antigen that is expressed by differentiated gastric mucosa cells. The expression of CLDN18.2 in gastric mucosa cells may be retained upon malignant transformation and is displayed on the surface of several tumors, including gastric/gastroesophageal junction adenocarcinoma. Zolbetuximab is a genetically engineered, highly purified chimeric (mouse/human IgG1) antibody directed against CLDN18.2. Nausea and vomiting were observed as adverse events of zolbetuximab. To investigate the mechanism of nausea and vomiting in humans, we evaluated emesis (retching and vomiting) and conducted histopathologic assessment in ferrets after the administration of zolbetuximab. Emesis was frequently observed in all ferrets treated with zolbetuximab in the first hour after administration. Histopathologic assessment revealed the surface of the gastric mucosa was the primary site of emesis-associated tissue damage. The effect of antiemetics (dexamethasone, ondansetron, fosaprepitant, and olanzapine) on emesis induced by zolbetuximab was investigated. Fosaprepitant showed suppressive effects on emesis, and use of dexamethasone or concomitant use of fosaprepitant with other antiemetics tended to alleviate gastric tissue damage. The onset of emesis in humans receiving zolbetuximab may be associated with damage in the gastric mucosa, and antiemetics may mitigate gastrointestinal adverse events.

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.

Evolving Treatment Landscape for Advanced Esophageal and Gastroesophageal Junction Adenocarcinoma

PURPOSE OF REVIEW

This review highlights advances and recent changes in the treatment paradigm for advanced esophageal adenocarcinoma (EAC) and gastroesophageal junction adenocarcinoma (GEJAC).

RECENT FINDINGS

Chemotherapy remains the backbone of treatment for advanced EAC/GEJAC. New targets/agents include immunotherapy, HER-2, claudin18.2, and FGFR2b, with various mechanisms (CAR-T, bispecific mAB, ADCs) altering the treatment landscape against these targets. The approaches to these targets may act together, in sequence, and even synergistically to improve outcomes. Herein, we review the state of the field, including highlighting ongoing clinical trials and additional emerging agents and approaches.

Consensus, debate, and prospective on pancreatic cancer treatments

Pancreatic cancer remains one of the most aggressive solid tumors. As a systemic disease, despite the improvement of multi-modality treatment strategies, the prognosis of pancreatic cancer was not improved dramatically. For resectable or borderline resectable patients, the surgical strategy centered on improving R0 resection rate is consensus; however, the role of neoadjuvant therapy in resectable patients and the optimal neoadjuvant therapy of chemotherapy with or without radiotherapy in borderline resectable patients were debated. Postoperative adjuvant chemotherapy of gemcitabine/capecitabine or mFOLFIRINOX is recommended regardless of the margin status. Chemotherapy as the first-line treatment strategy for advanced or metastatic patients included FOLFIRINOX, gemcitabine/nab-paclitaxel, or NALIRIFOX regimens whereas 5-FU plus liposomal irinotecan was the only standard of care second-line therapy. Immunotherapy is an innovative therapy although anti-PD-1 antibody is currently the only agent approved by for MSI-H, dMMR, or TMB-high solid tumors, which represent a very small subset of pancreatic cancers. Combination strategies to increase the immunogenicity and to overcome the immunosuppressive tumor microenvironment may sensitize pancreatic cancer to immunotherapy. Targeted therapies represented by PARP and KRAS inhibitors are also under investigation, showing benefits in improving progression-free survival and objective response rate. This review discusses the current treatment modalities and highlights innovative therapies for pancreatic cancer.

The Clinicopathological and Molecular Characteristics of Endocervical Gastric-Type Adenocarcinoma and the Use of Claudin18.2 as a Potential Therapeutic Target

Endocervical gastric-type adenocarcinoma (GAS) is an aggressive type of endocervical mucinous adenocarcinoma characterized as being unrelated to human papillomavirus (HPV) and resistant to chemo/radiotherapy. In this study, we investigated the histology, immunohistochemistry patterns, and molecular characteristics in a large cohort of GAS (n = 62). Histologically, the majority of GAS cases exhibited a distinct morphology resembling gastric glands, although 2 exceptional cases exhibited HPV-associated adenocarcinoma morphology while retaining the characteristic histology of GAS at the invasive front. By immunohistochemistry, Claudin18.2 emerged as a highly sensitive and specific marker for GAS. Additionally, the strong expression of Claudin18.2 in patients with GAS indicated the potential of anti-Claudin18.2 therapy in the treatment of GAS. Other immunohistochemistry markers, including Muc6, p16, p53, Pax8, ER, and PR, may provide additional diagnostic clues for GAS. Quantitative methylation analysis revealed that the overexpression of Claudin18.2 in GAS was governed by the hypomethylation of the CLDN18.2 promoter CpG islands. To further elucidate the pathogenic mechanisms of GAS and its relationship with gastric adenocarcinoma, we performed whole exome sequencing on 11 GAS and 9 gastric adenocarcinomas. TP53, CDKN2A, STK11, and TTN emerged as the most frequently mutated genes in GAS. Mutations in these genes primarily affected cell growth, cell cycle regulation, senescence, and apoptosis. Intriguingly, these top mutated genes in GAS were also commonly mutated in gastric and pancreaticobiliary adenocarcinomas. Regarding germline variants, we identified a probably pathogenic variant in SPINK1, a gene linked to hereditary pancreatic cancer syndrome, in one GAS sample. This finding suggests a potential pathogenic link between pancreatic cancers and GAS. Overall, GAS exhibits molecular characteristics that resemble those observed in gastric and pancreaticobiliary adenocarcinomas, thereby lending support to the aggressive nature of GAS compared with HPV-associated adenocarcinoma.

Expression profiles of cadherin 17 and claudin 18.2 in comparison with peptide hormonal expression in pancreatic neuroendocrine tumours: Implications for targeted immunotherapy

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.

Protein isoform-centric therapeutics: expanding targets and increasing specificity

Most protein-coding genes produce multiple protein isoforms; however, these isoforms are commonly neglected in drug discovery. The expression of protein isoforms can be specific to a disease, tissue and/or developmental stage, and this specific expression can be harnessed to achieve greater drug specificity than pan-targeting of all gene products and to enable improved treatments for diseases caused by aberrant protein isoform production. In recent years, several protein isoform-centric therapeutics have been developed. Here, we collate these studies and clinical trials to highlight three distinct but overlapping modes of action for protein isoform-centric drugs: isoform switching, isoform introduction or depletion, and modulation of isoform activity. In addition, we discuss how protein isoforms can be used clinically as targets for cell type-specific drug delivery and immunotherapy, diagnostic biomarkers and sources of cancer neoantigens. Collectively, we emphasize the value of a focus on isoforms as a route to discovering drugs with greater specificity and fewer adverse effects. This approach could enable the targeting of proteins for which pan-inhibition of all isoforms is toxic and poorly tolerated.

Expression of claudin 18.2 in poorly cohesive carcinoma and its association with clinicopathologic parameters in East Asian patients

BACKGROUND

Poorly cohesive carcinoma (PCC) is a distinct subtype of gastric cancer with limited therapeutic options. This study investigated claudin (CLDN) 18.2 expression status in PCCs using a 43-13 A clone.

METHODS

We retrospectively collected 178 consecutive surgically resected stage Ⅱ-Ⅲ gastric cancer samples. Tissue microarray blocks were constructed for CLDN18.2 immunohistochemical staining. We studied CLDN18.2 expression and its association with clinicopathologic parameters.

RESULTS

CLDN18.2 positivity (defined by ≥ 75 % of tumor cells showing moderate to strong membranous positivity) was found in 34.8 % of the PCC cases (62/178). Approximately half of the CLDN18.2 positive PCCs demonstrated heterogeneous expression (51.6 %, 32/62). CLDN18.2 positivity was not associated with any clinicopathologic parameters examined. However, CLDN18.2 positivity tended to be more frequent in E-cadherin-positive PCCs (no loss of expression) than in E-cadherin-negative PCCs (loss of expression) (50 % vs. 27.7 %). The CLDN18.2 expression level, represented by the H-score, gradually decreased as the paraffin block storage time increased (P = 0.046). Overall survival and disease-free survival analyses showed no significant difference between CLDN18.2-positive and negative PCCs.

CONCLUSIONS

A significant portion of surgically resected PCC specimens showed CLDN18.2 positivity. Additionally, since the expression level of CLDN18.2 gradually decreases with increased paraffin block storage time, reflex testing can be considered at the time of the cancer diagnosis.

Claudins: from gatekeepers of epithelial integrity to potential targets in hepato-pancreato-biliary cancers

Claudins, a family of tetraspan transmembrane proteins, are critical to the integrity of tight junctions in epithelia and endothelia, influencing cellular processes such as development, differentiation, and apoptosis. Abnormal claudin expression is associated with various malignancies, particularly affecting tissue architecture and potentially facilitating tumor invasion and metastasis. In this comprehensive review, we explore the multifaceted functions of claudins: their expression, specific roles in cancer with a focus on hepato-pancreato-biliary malignancies and highlight their potential as therapeutic targets. We discuss current claudin-targeted therapies, including monoclonal antibodies, antibody-drug conjugates, bispecific T-cell engager and chimeric antigen receptor T-cell therapies. These approaches show promise in pre-clinical and clinical studies, particularly in hepato-pancreato-biliary cancers with large unmet needs. Despite these early signs of efficacy, challenges remain in effectively targeting these proteins due to their structural resemblance and overlapping functions.

Expression and Targeted Application of Claudins Family in Hepatobiliary and Pancreatic Diseases

Hepatobiliary and pancreatic diseases are becoming increasingly common worldwide and associated cancers are prone to recurrence and metastasis. For a more accurate treatment, new therapeutic strategies are urgently needed. The claudins (CLDN) family comprises a class of membrane proteins that are the main components of tight junctions, and are essential for forming intercellular barriers and maintaining cellular polarity. In mammals, the claudin family contains at least 27 transmembrane proteins and plays a major role in mediating cell adhesion and paracellular permeability. Multiple claudin proteins are altered in various cancers, including gastric cancer (GC), esophageal cancer (EC), hepatocellular carcinoma (HCC), pancreatic cancer (PC), colorectal cancer (CRC) and breast cancer (BC). An increasing number of studies have shown that claudins are closely associated with the occurrence and development of hepatobiliary and pancreatic diseases. Interestingly, claudin proteins exhibit different effects on cancer progression in different tumor tissues, including tumor suppression and promotion. In addition, various claudin proteins are currently being studied as potential diagnostic and therapeutic targets, including claudin-3, claudin-4, claudin-18.2, etc. In this article, the functional phenotype, molecular mechanism, and targeted application of the claudin family in hepatobiliary and pancreatic diseases are reviewed, with an emphasis on claudin-1, claudin-4, claudin-7 and claudin-18.2, and the current situation and future prospects are proposed.

Deciphering the role of claudins in lung cancer

Lung cancer remains a major global health challenge, characterized by aggressive malignancy and poor prognostic outcomes. This review article focuses on the pivotal role of claudins, a family of tight junction proteins, in the pathophysiology of lung cancer. Claudins are integral to maintaining epithelial barrier function and cellular polarity, yet they are intricately involved in the progression and metastasis of lung cancer. The aberrant expression of claudins has been observed across various histological subtypes of lung cancer, indicating their potential as diagnostic and prognostic biomarkers. Specifically, claudins such as claudin-1, -2, -3, -4, and -7 exhibit diverse expression patterns that correlate with tumor aggressiveness, patient survival rates, and response to therapies. Inflammation and cytokine modulation significantly influence claudin expression, affecting tumor microenvironment dynamics and cancer progression. This review also highlights the therapeutic implications of targeting claudins, particularly in cases resistant to conventional treatments. Recent advances in this area suggest that claudin-modulating agents may enhance the efficacy of existing therapies and offer new avenues for targeted interventions. By integrating the latest research, this article aims to provide a comprehensive understanding of claudin's roles in lung cancer and encourages further clinical trials to explore claudin-targeting therapies. This could pave the way for more effective management strategies, improving outcomes for lung cancer patients.

CMG901, a Claudin18.2-specific antibody-drug conjugate, for the treatment of solid tumors

Claudin18.2 has been recently recognized as a potential therapeutic target for gastric/gastroesophageal junction or pancreatic cancer. Here, we develop a Claudin18.2-directed antibody-drug conjugate (ADC), CMG901, with a potent microtubule-targeting agent MMAE (monomethyl auristatin E) and evaluate its preclinical profiles. In vitro studies show that CMG901 binds specifically to Claudin18.2 on the cell surface and kills tumor cells through direct cytotoxicity, antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and bystander killing activity. In vivo pharmacological studies show significant antitumor activity in patient-derived xenograft (PDX) models. Toxicity studies show that the major adverse effects related to CMG901 are reversible hematopoietic changes attributed to MMAE. The highest non-severely toxic dose (HNSTD) is 6 mg/kg in cynomolgus monkeys and 10 mg/kg in rats once every 3 weeks. CMG901's favorable preclinical profile supports its entry into the human clinical study. CMG901 is currently under phase 3 investigation in patients with advanced gastric/gastroesophageal junction adenocarcinoma expressing Claudin18.2 (NCT06346392).

Diffuse Gastric Cancer: A Comprehensive Review of Molecular Features and Emerging Therapeutics

Diffuse-type gastric cancer (DGC) accounts for approximately one-third of gastric cancer diagnoses but is a more clinically aggressive disease with peritoneal metastases and inferior survival compared with intestinal-type gastric cancer (IGC). The understanding of the pathogenesis of DGC has been relatively limited until recently. Multiomic studies, particularly by The Cancer Genome Atlas, have better characterized gastric adenocarcinoma into molecular subtypes. DGC has unique molecular features, including alterations in CDH1, RHOA, and CLDN18-ARHGAP26 fusions. Preclinical models of DGC characterized by these molecular alterations have generated insight into mechanisms of pathogenesis and signaling pathway abnormalities. The currently approved therapies for treatment of gastric cancer generally provide less clinical benefit in patients with DGC. Based on recent phase II/III clinical trials, there is excitement surrounding Claudin 18.2-based and FGFR2b-directed therapies, which capitalize on unique biomarkers that are enriched in the DGC populations. There are numerous therapies targeting Claudin 18.2 and FGFR2b in various stages of preclinical and clinical development. Additionally, there have been preclinical advancements in exploiting unique therapeutic vulnerabilities in several models of DGC through targeting of the focal adhesion kinase (FAK) and Hippo pathways. These preclinical and clinical advancements represent a promising future for the treatment of DGC.

Progresses of T-cell-engaging bispecific antibodies in treatment of solid tumors

T-cell-engaging bispecific antibody (TCB) therapies have emerged as a promising immunotherapeutic approach, effectively redirecting effector T cells to selectively eliminate tumor cells. The therapeutic potential of TCBs has been well recognized, particularly with the approval of multiple TCBs in recent years for the treatment of hematologic malignancies as well as some solid tumors. However, TCBs encounter multiple challenges in treating solid tumors, such as on-target off-tumor toxicity, cytokine release syndrome (CRS), and T cell dysfunction within the immunosuppressive tumor microenvironment, all of which may impact their therapeutic efficacy. In this review, we summarize clinical data on TCBs for solid tumor treatment, highlight the challenges faced, and discuss potential solutions based on emerging strategies from current clinical and preclinical research. These solutions include TCB structural optimization, target selection, and combination strategies. This comprehensive analysis aims to guide the development of TCBs from design to clinical application, addressing the evolving landscape of cancer immunotherapy.

The Road Ahead in Pancreatic Cancer: Emerging Trends and Therapeutic Prospects

This review explores the challenges and emerging trends in pancreatic cancer therapy. In particular, we focus on the tumor microenvironment and the potential of immunotherapy for pancreatic cancer. Pancreatic ductal adenocarcinoma, characterized by its dense stromal architecture, presents unique challenges for effective treatment. Recent advancements have emphasized the role of the tumor microenvironment in therapeutic resistance and disease progression. We discuss novel strategies targeting the desmoplastic barrier and immunosuppressive cells to enhance immune cell infiltration and activation. Recent clinical trials, particularly those involving novel immunotherapeutic agents and tumor vaccines, are examined to understand their efficacy and limitations. Our analysis reveals that combining immunotherapy with chemotherapy, radiation therapy, or drugs targeting epigenetic processes shows promise, improving overall survival rates and response to treatment. For instance, trials utilizing checkpoint inhibitors in combination with standard chemotherapies have extended disease-free survival by up to 6 months compared to chemotherapy alone. Importantly, vaccines targeting specific tumor neoantigens have shown the potential to increase patient survival. However, these approaches also face significant challenges, including overcoming the immunosuppressive tumor microenvironment and enhancing the delivery and efficacy of therapeutic agents. By providing an overview of both the promising results and the obstacles encountered, this review aims to highlight ongoing efforts to refine immunotherapy approaches for better patient outcomes.

Extent and clinical significance of the therapy-relevant tight junction protein Claudin 18.2 in pancreatic ductal adenocarcinoma - real-world evidence

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is associated with poor prognosis, wherefore targeted therapies have experienced increasing interest. Zolbetuximab is a novel targeted therapy under investigation in patients with PDAC and targets Claudin 18.2 (CLDN18.2), which is a component of tight junctions and is of significance in various solid tumors. As its role in PDAC is not definitively elucidated, this study aims to clarify the significance of CLDN18.2 expression in PDAC in a real-world setting.

METHODS

All patients (n = 309) were recruited at one of the PANCALYZE study centers and received pancreatic resection with curative intention. Paraffin samples were analyzed using an antibody against CLDN18.2, which is known to be comparable to the antibody used by the SPOTLIGHT and GLOW studies.

RESULTS

94 PDACs are positive for CLDN18.2 (30.4 %). Positive CLDN 18.2 expression was associated with significantly better cancer differentiation (p < 0.001). Patients with positive CLDN18.2 expression showed significantly better overall survival when compared to patients with negative expression (median OS: 30 versus 18 months, p = 0.003). Additionally, in multivariable analyses, CLDN18.2 expression was identified as an independent factor for better survival in patients with PDAC (HR = 0.686, 95 %CI = 0.492-0.956, p = 0.026).

CONCLUSION

Significant improvement in survival could be demonstrated by adding Zolbetuximab to known chemotherapy regimes in patients with gastro-esophageal junction adenocarcinoma with at least 75 % CLDN18.2 positive cancer cells. Our findings demonstrate, that 30.4 % of the included patients with PDAC would potentially be eligible for therapy with Zolbetuximab in a real-world patient cohort. Results of trials targeting Claudin 18.2 are pending in patients with PDAC.

Global prevalence of claudin 18 isoform 2 in tumors of patients with locally advanced unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma

BACKGROUND

Limited data exist for global prevalence of claudin 18 isoform 2 (CLDN18.2) positivity and association of CLDN18.2 status with clinical and tumor characteristics in patients with locally advanced (LA) unresectable or metastatic gastric or gastroesophageal junction (mG/GEJ) adenocarcinoma. We report prevalence of CLDN18.2 positivity (phase 3; SPOTLIGHT, NCT03504397; GLOW, NCT03653507) and concordance of CLDN18.2 status between a subset of pair-matched tumor samples (phase 2, ILUSTRO, NCT03505320; phase 1, NCT03528629) from clinical studies of zolbetuximab.

METHODS

Tumor samples from patients with LA unresectable or mG/GEJ adenocarcinoma were tested for CLDN18.2 status by immunohistochemistry. Human epidermal growth factor receptor 2 (HER2) expression was tested per central or local assessment.

RESULTS

Across SPOTLIGHT and GLOW, the prevalence of CLDN18.2 positivity (≥ 75% of tumor cells demonstrating moderate-to-strong membranous CLDN18 staining) was 38.4%. Prevalence was similar in gastric versus GEJ adenocarcinoma samples and regardless of collection method (biopsy versus resection) or collection site (primary versus metastatic). CLDN18.2 positivity was most prevalent in patients with diffuse-type tumors. In ILUSTRO and the phase 1 study, concordance of CLDN18.2 positivity was 61.1% between archival (i.e., any time before treatment) and baseline (i.e., ≤ 3 months before first treatment) samples, and concordance of any CLDN18 staining (≥ 1% of tumor cells demonstrating moderate-to-strong membranous CLDN18 staining) was 88.9%.

CONCLUSIONS

CLDN18.2 was a highly prevalent biomarker in patients with HER2-negative, LA unresectable or mG/GEJ adenocarcinoma. CLDN18.2 positivity remained relatively stable over time in many patients. Biomarker testing for CLDN18.2 should be considered in standard clinical practice in these patients.

The impact of CLDN18.2 expression on effector cells mediating antibody-dependent cellular cytotoxicity in gastric cancer

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 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).

The preclinical discovery and development of zolbetuximab for the treatment of gastric cancer

INTRODUCTION

Gastric cancer remains a formidable challenge in oncology with high mortality rates and few advancements in treatment. Claudin-18.2 (CLDN18.2) is a tight junction protein primarily expressed in the stomach and is frequently overexpressed in certain subsets of gastric cancers. Targeting CLDN18.2 with monoclonal antibodies, such as zolbetuximab (IMAB362), has shown promising efficacy results in combination with chemotherapy.

AREAS COVERED

The molecular cell biology of CLDN18.2 is discussed along with studies demonstrating the utility of CLDN18.2 expression as a biomarker and therapeutic target. Important clinical studies are reviewed, including Phase III trials, SPOTLIGHT and GLOW, which demonstrate the efficacy of zolbetuximab in combination with chemotherapy in patients with CLDN18.2-positive advanced gastric cancer.

EXPERT OPINION

CLDN18.2 is involved in gastric differentiation through maintenance of epithelial barrier function and coordination of signaling pathways, and its expression in gastric cancers reflects a 'gastric differentiation' program. Targeting Claudin-18.2 represents the first gastric cancer specific 'targeted' treatment. Further studies are needed to determine its role within current gastric cancer treatment sequencing, including HER2-targeted therapies and immunotherapies. Management strategies will also be needed to better mitigate zolbetuximab-related treatment side effects, including gastrointestinal (GI) toxicities.

Zolbetuximab: First Approval

Zolbetuximab (VYLOY™), a recombinant, chimeric, anti-claudin 18.2 (CLDN18.2) monoclonal antibody (mAb), is being developed by Astellas Pharma Inc. for the treatment of patients with HER2-negative (HER2-), CLDN18.2-positive (CLDN18.2+) advanced gastric or gastroesophageal junction (GEJ) adenocarcinoma and CLDN18.2+ advanced pancreatic adenocarcinoma. In March 2024, zolbetuximab was approved in Japan for the treatment of patients with HER2-, CLDN18.2+ unresectable, advanced/recurrent gastric cancer (the gastric cancer indication includes GEJ cancer). Zolbetuximab is also undergoing regulatory review for HER2-, CLDN18.2+ advanced gastric or GEJ adenocarcinoma in the USA, the EU, China, Australia and several other countries. This article summarizes the milestones in the development of zolbetuximab leading to this first approval for the treatment of patients with CLDN18.2+ gastrointestinal malignancies.

Health-related quality of life in patients with CLDN18.2-positive, locally advanced unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma: results from the SPOTLIGHT and GLOW clinical trials

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.

MATERIALS AND 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.

The E3 ubiquitin ligase TRIP12 is required for pancreatic acinar cell plasticity and pancreatic carcinogenesis

The E3 ubiquitin ligase thyroid hormone receptor interacting protein 12 (TRIP12) has been implicated in pancreatic adenocarcinoma (PDAC) through its role in mediating the degradation of pancreas transcription factor 1a (PTF1a). PTF1a is a transcription factor essential for the acinar differentiation state that is notably diminished during the early steps of pancreatic carcinogenesis. Despite these findings, the direct involvement of TRIP12 in the onset of pancreatic cancer has yet to be established. In this study, we demonstrated that TRIP12 protein was significantly upregulated in human pancreatic preneoplastic lesions. Furthermore, we observed that TRIP12 overexpression varied within PDAC samples and PDAC-derived cell lines. We further demonstrated that TRIP12 was required for PDAC-derived cell growth and for the expression of E2F-targeted genes. Acinar-to-ductal cell metaplasia (ADM) is a reversible process that reflects the high plasticity of acinar cells. ADM becomes irreversible in the presence of oncogenic Kras mutations and leads to the formation of preneoplastic lesions. Using two genetically modified mouse models, we showed that a loss of TRIP12 prevented acini from developing ADM in response to pancreatic injury. With two additional mouse models, we further discovered that a depletion of TRIP12 prevented the formation of KrasG12D-induced preneoplastic lesions and impaired metastasis formation in the presence of mutated KrasG12D and Trp53R172H genes. In summary our study identified an overexpression of TRIP12 from the early stages of pancreatic carcinogenesis and proposed this E3 ubiquitin ligase as a novel regulator of acinar plasticity with an important dual role in initiation and metastatic steps of PDAC. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Heterogeneity of claudin 18.2 expression in metastatic gastric cancer

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.

A novel highly sensitive inner filter effect-based fluorescence immunoassay with quantum dots for bioanalysis of zolbetuximab, a monoclonal antibody used for immunotherapy of gastric and gastroesophageal junction adenocarcinoma

Zolbetuximab (ZOL) is a groundbreaking monoclonal antibody targeting CLDN 18.2, a cancer cell surface protein. It is a first-in-class therapy for gastric and gastroesophageal junction adenocarcinoma. However, there is currently any immunoassay available for bioanalysis of ZOL, hindering its pharmacokinetic studies, therapeutic monitoring, and safety profile refinement. To address this gap, this study presents the development and validation of a novel highly sensitive inner filter effect-based fluorescence immunoassay (IFE-FIA) with quantum dots (QDs) as a probe. This assay enables the quantitative determination of ZOL in plasma samples. The assay involved non-competitive capturing of ZOL from the samples using a specific antigen (CLDN 18.2 protein) immobilized on assay plate microwells. A horseradish peroxidase (HRP)-labelled anti-human IgG was used to measure the immune complex. The assay's detection system relies on the formation of a light-absorbing colored product through an HRP-catalyzed oxidative reaction with the substrate 3,3',5,5'-tetramethylbenzidine. This light absorption efficiently quenched the fluorescence of QDs via the IFE. The measured fluorescence signals corresponded to the concentrations of ZOL in the samples. The conditions of the IFE-FIA and its detection system were refined, and the optimum procedures were established. Following the guidelines of immunoassay validation for bioanalysis, the assay was validated, and all the validation criteria were acceptable. The assay demonstrates high sensitivity, accurately quantifying ZOL at concentrations as low as 10 ng/mL in plasma samples, with acceptable precision. Importantly, it avoids interferences from endogenous substances and plasma matrix. The recoveries in spiked human plasma ranged from 96.8 % to 104.5 %, with relative standard deviations of 4.1 %-6.5 %. The proposed IFE-FIA represents a valuable tool for quantifying ZOL in clinical settings, enabling assessment of its pharmacokinetics, therapeutic drug monitoring, and safety profile refinement.

Molecular SPECT/CT Profiling of Claudin18.2 Expression In Vivo: Implication for Patients with Gastric Cancer

Zolbetuximab (IMAB362), a monoclonal antibody targeting Claudin18.2 (CLDN 18.2), demonstrates a significant clinical benefit in patients with advanced gastroesophageal cancers. The noninvasive assessment of CLDN18.2 expression through molecular imaging offers a potential avenue for expedited monitoring and the stratification of patients into risk groups. This study elucidates that CLDN18.2 is expressed at a noteworthy frequency in primary gastric cancers and their metastases. The iodogen method was employed to label IMAB362 with 123I/131I. The results demonstrated the efficient and reproducible synthesis of 123I-IMAB362, with a specific binding affinity to CLDN18.2. Immuno-single-photon emission computed tomography (SPECT) imaging revealed the rapid accumulation of 123I-IMAB362 in gastric cancer xenografts at 12 h, remaining stable for 3 days in patient-derived tumor xenograft models. Additionally, tracer uptake of 123I-IMAB362 in MKN45 cells surpassed that in MKN28 cells at each time point, with tumor uptake correlating significantly with CLDN18.2 expression levels. Positron emission tomography/computed tomography imaging indicated that tumor uptake of 18F-FDG and the functional/viable tumor volume in the 131I-IMAB362 group were significantly lower than those in the 123I-IMAB362 group on day 7. In conclusion, 123I-IMAB362 immuno-SPECT imaging offers an effective method for direct, noninvasive, and whole-body quantitative assessment of tumor CLDN18.2 expression in vivo. This approach holds promise for accelerating the monitoring and stratification of patients with gastric cancer.

Effect of anti-claudin 18.2 monoclonal antibody zolbetuximab alone or combined with chemotherapy or programmed cell death-1 blockade in syngeneic and xenograft gastric cancer models

The development of targeted cancer therapies based on monoclonal antibodies against tumor-associated antigens has progressed markedly over recent decades. This approach is dependent on the identification of tumor-specific, normal tissue-sparing antigenic targets. The transmembrane protein claudin-18 splice variant 2 (CLDN18.2) is frequently and preferentially displayed on the surface of primary gastric adenocarcinomas, making it a promising monoclonal antibody target. Phase 3 studies of zolbetuximab, a chimeric immunoglobulin G1 monoclonal antibody targeting CLDN18.2, combined with 5-fluorouracil/leucovorin plus oxaliplatin (modified FOLFOX6) or capecitabine plus oxaliplatin (CAPOX) in advanced or metastatic first-line gastric or gastroesophageal junction (G/GEJ) adenocarcinoma have demonstrated favorable clinical results with zolbetuximab. In studies using xenograft or syngeneic models with gastric cancer cell lines, zolbetuximab mediated death of CLDN18.2-positive human cancer cell lines via antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity in vitro and demonstrated anti-tumor efficacy as monotherapy and combined with chemotherapy in vivo. Mice treated with zolbetuximab plus chemotherapy displayed a significantly higher frequency of tumor-infiltrating CD8+ T cells versus vehicle/isotype control-treated mice. Furthermore, zolbetuximab combined with an anti-mouse programmed cell death-1 antibody more potently inhibited tumor growth compared with either agent alone. These results support the potential of zolbetuximab as a novel treatment option for G/GEJ adenocarcinoma.

Biomarker-oriented chemo-immunotherapy for advanced gastric cancer

The biomarker-oriented chemo-immunotherapy is useful and promising in the development of new anticancer agents, since the responders can be enriched by selecting patients with biomarkers. Compared to colorectal and lung cancers, the development of biomarker-driven molecular-targeted therapeutics for gastric cancers has been straggled. However, several new biomarkers in gastric cancers have been discovered and clinical trials in enrichment design with certain biomarkers have been conducted. Therefore, there are currently several treatment options to treat gastric cancer patients based on individual biomarker-oriented strategies. In the present review, we describe the useful biomarkers in gastric cancer, with focusing on HER2, PD-L1, and Claudin18.2, in relation to their clinical significance and associated targeted agents.

Spatial expression of claudin 18.2 in matched primaries and metastases of tubo-ovarian carcinoma of all subtypes

Physiologically, claudin 18 splice variant 2 (CLDN18.2) expression is restricted to the gastric epithelium, but its expression has been detected in solid cancers. Zolbetuximab, a chimeric IgG1 antibody targeting CLDN18.2, has demonstrated promising effects in patients suffering from CLDN18.2-positive, HER2-negative locally advanced gastric cancer and is currently being studied further. To date, little is known about CLDN18.2 expression in other histological subtypes of tubo-ovarian carcinoma (TOC) and their matching metastases.Using a cohort of all histological TOC subtypes, we investigated the immunohistochemical (IHC) CLDN18.2 expression in both TOCs (n = 536), their matching metastatic tissue (n = 385) and in 93 metastases without primary. Tissue microarrays comprised both the tumor center and periphery. IHC positivity was defined as biomarker expression of ≥ 75% in tumor cells with moderate-to-strong membranous staining.Overall CLDN18.2 positivity was 4.1% (21/515) in the TOC centers and 3.6% (18/498) in their peripheries. In primaries of mucinous tubo-ovarian carcinoma (MTOC), CLDN18.2 positivity rates were 45% (18/40) and 36.6% (15/41), respectively. Positivity rates for the corresponding metastases were 33% (4/12, center) and 27% (3/11, periphery). The expression was relatively homogenous throughout all tumor sites. With no expression in 99.5% of nonmucinous tumors, CLDN18.2 positivity was almost exclusively seen in the mucinous subtype.In tubo-ovarian carcinoma, CLDN18.2 expression was, with rare exceptions, restricted to the mucinous subtype. Among them, 33% of metastasized MTOCs presented with CLDN18.2 positivity. Hence, CLDN18.2 might display a promising target for personalized therapy in patients with advanced MTOC.

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.

Progress of Clinical Studies Targeting Claudin18.2 for the Treatment of Gastric Cancer

Claudin18.2 is a tight junction protein, highly selective, generally expressed only in normal gastric mucosal epithelial cells, which can effectively maintain the polarity of epithelial and endothelial cells, thus effectively regulating the permeability and conductance of the paracellular pathway. Abnormal expression of Claudin18.2 can occur in various primary malignant tumors, especially gastrointestinal tumors, and even in metastatic foci. It regulates its expression by activating the aPKC/MAPK/AP-1 pathway, and therefore, the Claudin18.2 protein is a pan-cancer target expressed in primary and metastatic lesions in human cancer types. Zolbetuximab (IMAB362), an antibody specific for Claudin18.2, has been successfully tested in a phase III clinical trial, and the results of the study showed that combining Zolbetuximab with chemotherapy notably extends patients' survival and is expected to be a potential first-line treatment for patients with Claudin18.2(+)/HER-2(-) gastric cancer. Here, we systematically describe the biological properties and oncogenic effects of Claudin18.2, centering on its clinical-pathological aspects and the progress of drug studies in gastric cancer, which can help to further explore its clinical value.

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.

Molecular Pathology of Gastroesophageal Cancer

Upper gastroesophageal carcinomas consist of cancers arising from the esophagus and stomach. Squamous cell carcinomas and adenocarcinomas are seen in the esophagus and despite arising from the same organ have different biology. Gastric adenocarcinomas are categorized into 4 molecular subtypes: high Epstein-Barr virus load, microsatellite unstable cancers, chromosomal unstable (CIN) cancers, and genomically stable cancers. Genomically stable gastric cancers correlate highly with histologically defined diffuse-type cancers. Esophageal carcinomas and CIN gastric cancers often are driven by high-level amplifications of oncogenes and contain a high degree of intratumoral heterogeneity. Targeted therapeutics is an active area of research for gastroesophageal cancers.

Current and Future Biomarkers in Esophagogastric Adenocarcinoma

PURPOSE

Biomarker-based therapies have shown improved patient outcomes across various cancer types. The purpose of this review to summarize our knowledge of current and future biomarkers in esophagogastric adenocarcinoma (EGA).

METHODS

In this publication, we will review current standard biomarkers in patients with upper GI cancers. We will also discuss novel biomarkers that are under investigations and their associated therapies that are currently in clinical trials.

RESULTS

EGAa are a group of heterogeneous diseases, both anatomically and molecularly. There are several established biomarkers (HER2, PD-L1, microsattelite instability or mismatch repair protein expression) that allow for individualized treatments for patients with these cancers. There are also several emerging biomarkers for EGA, some of which have clinically relevant associated therapies. Claudin 18.2 is the furthest along among these. Anti-claudin antibody, zolbetuximab, improved overall survival in biomarker select patients with advanced GEA in two phase 3 studies. Other novel biomarkers, such as FGFR2b and DKN01, are also in the process of validation, and treatments based on the presence of these biomarkers are currently in clinical studies.

CONCLUSION

Ongoing efforts to identify novel biomarkers in EGA have led to enhanced subclassification of upper GI cancers. These advances, coupled with the strategic application of targeted therapies and immunotherapy when appropriate, hold promise to further improve patients outcomes.

Incorporating Molecular Data Into Treatment Decision Making in Gastroesophageal and Pancreaticobiliary Cancers: Timing and Strategies

Gastroesophageal (GE) and pancreatobiliary (PB) cancers represent a significant clinical challenge. In this context, it is critical to understand the key molecular targets within these malignancies including how they are assayed for as well as the clinical actionability of these targets. Integrating biomarkers into the standard of care presents a critical avenue for refining treatment paradigms. This review aims to explore these complexities, offering insights into the optimal sequencing of chemotherapy and targeted therapies and their utility in the management of GE and PB cancers. The timely integration of promising investigational therapies into clinical practice has broader implications around strategies for future clinical trial designs, which would pave the way for advancements in the management of GE and PB cancers. This review provides guidance in navigating the evolving landscape of GE and PB cancer care, which ultimately will drive forward progress in the field and lead to improved patient outcomes.

Targeted Agents in Esophagogastric Cancer Beyond Human Epidermal Growth Factor Receptor-2

Gastroesophageal cancers are highly diverse tumors in terms of their anatomic and molecular characteristics, making drug development challenging. Recent advancements in understanding the molecular profiles of these cancers have led to the identification of several new biomarkers. Ongoing clinical trials are investigating new targeted agents with promising results. CLDN18.2 has emerged as a biomarker with established activity of associated targeted therapies. Other targeted agents, such as bemarituzumab and DKN-01, are under active investigation. As new agents are incorporated into the treatment continuum, the questions of biomarker overlap, tumor heterogeneity, and toxicity management will need to be addressed.

Recent Advances in Radiotracers Targeting Novel Cancer-Specific Biomarkers in China: A Brief Overview

Radiopharmaceuticals play a critical role in nuclear medicine, providing novel tools for specifically delivering radioisotopes for the diagnosis and treatment of cancers. As the starting point for developing radiopharmaceuticals, cancer-specific biomarkers are important and receive worldwide attention. This field in China is currently experiencing a rapid expansion, with multiple radiotracers targeting novel targets being developed and translated into clinical studies. This review provides a brief overview of the exploration of novel imaging targets, preclinical evaluation of their targeting ligands, and translational research in China from 2020 to 2023, for detecting cancer, guiding targeted therapy, and visualizing the immune microenvironment. We believe that China will play an even more important role in the development of nuclear medicine in the world in the future.

Claudin 18.2 as a novel therapeutic target

Claudin 18.2, a tight-junction molecule predominantly found in the nonmalignant gastric epithelium, becomes accessible on the tumour cell surface during malignant transformation, thereby providing an appealing target for cancer therapy. Data from two phase III trials testing the anti-claudin 18.2 antibody zolbetuximab have established claudin 18.2-positive advanced-stage gastric cancers as an independent therapeutic subset that derives benefit from the addition of this agent to chemotherapy. This development has substantially increased the percentage of patients eligible for targeted therapy. Furthermore, newer treatments, such as high-affinity monoclonal antibodies, bispecific antibodies, chimeric antigen receptor T cells and antibody-drug conjugates capable of bystander killing effects, have shown considerable promise in patients with claudin 18.2-expressing gastric cancers. This new development has resulted from drug developers moving beyond traditional targets, such as driver gene alterations or growth factors. In this Review, we highlight the biological rationale and explore the clinical activity of therapies that target claudin 18.2 in patients with advanced-stage gastric cancer and explore the potential for expansion of claudin 18.2-targeted therapies to patients with other claudin 18.2-positive solid tumours.

Safety and Pharmacokinetic Assessment of the FIC CLDN18.2/4-1BB Bispecific Antibody in Rhesus Monkeys

Gastric cancer is one of the most common cancers worldwide, particularly in China, with over half a million new cases and over 400 thousand deaths in 2022. Zolbetuximab, a first-in-class investigational monoclonal antibody (mAb) targeting tumor-associated antigen CLDN18.2 which is highly expressed on gastric cancer cells, was recently reported to meet the primary endpoint in Phase III trial as first-line treatment in CLDN18.2 positive and HER2-negative gastric cancers. In the present study, we developed a humanized bispecific antibody (bsAb) CLDN18.2/4-1BB named PM1032. PM1032 activates immune cells via CLDN18.2 mediated crosslinking of 4-1BB, a potent stimulator of T/NK cells. It induced strong immunological memory in multiple tumor-bearing animal models, indicating significant potential as an effective treatment for CLDN18.2 positive cancers such as gastric cancer. Since liver and gastrointestinal (GI) related toxicities were reported in 4-1BB and CLDN18.2 targeting programs during the clinical development, respectively, extensive pharmacokinetics (PK) and safety profile characterization of PM1032 was performed in rhesus monkeys. PM1032 had a half-life comparable to a conventional IgG1 mAb, and serum drug concentration increased in a dose-dependent pattern. Furthermore, PM1032 was generally well tolerated, with no significant abnormalities observed in toxicity studies, including the liver and stomach. In summary, PM1032 demonstrated good PK and an exceptional safety profile in rhesus monkeys supporting further investigation in clinical studies.

Claudin 18.2 expression in digestive neuroendocrine neoplasms: a clinicopathological study

BACKGROUND

Claudin 18.2-targeted therapy has shown significant efficacy in treating claudin 18.2-positive cancers. However, limited systematic studies have investigated characteristics of claudin 18.2 expression in neuroendocrine neoplasms (NENs).

METHODS

Data and specimens from 403 cases of digestive NENs were retrospectively collected, and claudin 18.2 expression was detected using immunochemical staining.

RESULTS

Claudin 18.2 was positive in 19.6% (79/403) of the digestive NENs. The highest positive rate of claudin 18.2 was observed in gastric NENs (72/259, 27.8%), accounting for 91.1% (72/79) of all positive cases. The positivity rate was significantly higher in gastric NENs compared to pancreatic (2/78, 2.6%) or colorectal NENs (2/38, 5.3%; p < 0.05). For digestive NENs, claudin 18.2 positivity was significantly higher in neuroendocrine carcinomas (NECs) (37/144, 25.7%) than in neuroendocrine tumours (NETs; 14/160, 8.8%; p < 0.001), but no significant difference was found between gastric NECs (59/213, 27.7%) and gastric NETs (13/46, 28.3%; p > 0.05). The positivity was significantly higher in large-cell NECs (LCNECs; 28/79, 35.4%) and MiNEN (mixed neuroendocrine-non- neuroendocrine neoplasms)-LCNECs (23/66, 34.8%) compared to small-cell NECs (SCNECs; 9/65, 13.8%) and MiNEN-SCNECs (5/33, 15.2%; p < 0.05). Claudin 18.2 expression was more prevalent in gastric NENs than in pancreatic (12.5 ×; p = 0.001) and colorectal NENs (5.9 ×; p = 0.021). Claudin 18.2 staining was a useful method for identify the gastric origins of NETs, with a sensitivity of 28.3% and a specificity of 99.1%.

CONCLUSION

The expression characteristics of claudin 18.2 in NENs were characterized, which may provide a clinicopathological reference for targeted therapies in patients with NENs.

Retrospective Study of Claudin 18 Isoform 2 Prevalence and Prognostic Association in Gastric and Gastroesophageal Junction Adenocarcinoma

PURPOSE

Claudin 18 isoform 2 (CLDN18.2) is an emerging biomarker and therapeutic target in gastric and gastroesophageal junction (G/GEJ) adenocarcinoma. This study aimed to obtain deeper understanding of CLDN18.2 positivity patterns, prognostic implications, and associations with various demographic, clinical, and molecular characteristics in G/GEJ adenocarcinoma.

METHODS

Archived tumor tissue samples from 304 patients with G/GEJ adenocarcinoma in the United States were assessed for CLDN18.2 positivity by immunohistochemistry. CLDN18.2 positivity was defined as ≥50% or ≥75% of tumor cells with CLDN18 staining intensity ≥2+. CLDN18.2 positivity patterns were analyzed for association with prognosis and clinicopathologic/demographic characteristics. Where possible, CLDN18.2 positivity was analyzed for matched tissue samples to assess concordance between primary and metastatic tumors and concordance before and after chemotherapy.

RESULTS

The overall prevalence of CLDN18.2-positive tumors (with ≥75% cutoff) was 44.4% (n = 135 of 304). CLDN18.2-positive tumors had a prevalence of 51.4% (n = 91 of 177) in gastric and 34.6% (n = 44 of 127) in GEJ adenocarcinoma. With a ≥50% cutoff, the prevalence of CLDN18.2-positive tumors was 64.4% (n = 114 of 177) in gastric adenocarcinoma and 44.9% (n = 57 of 127) in GEJ adenocarcinoma. There was no association between overall survival and CLDN18.2 positivity using either threshold. Statistically significant associations were noted between CLDN18.2 positivity and sex, histologic type of G/GEJ adenocarcinoma, and adenocarcinoma subtype (≥75% cutoff), and metastasis site and tumor grade (≥50% cutoff). The overall concordance of CLDN18.2 positivity (≥75% cutoff) was 73% (27 of 37) for matched primary versus metastatic tumor samples and 74% (29 of 39) for matched samples before and after chemotherapy.

CONCLUSION

This study demonstrated that CLDN18.2 positivity did not correlate with survival in G/GEJ adenocarcinoma, consistent with published data. On the basis of matched sample analysis, CLDN18.2 appears to demonstrate >70% concordance as a biomarker. Observed correlations with certain patient/tumor characteristics warrant further study.

High Expression of CLDN 18.2 is Associated with Poor Disease-Free Survival of HER-2 Positive Gastric Cancer

Background

Anti-claudin (CLDN) 18.2 therapy has been proven to be effective in treating advanced gastric cancer with negative human epidermal growth factor receptor 2 (HER-2). This study purposed to investigate the relationship of CLDN 18.2 expression with prognosis of HER-2-positive gastric cancer patients.

Objective

To investigate the expression of claudin (CLDN) 18.2 in Human epidermal growth factor receptor 2 (HER-2) positive gastric cancer patients after radical resection and its relationship with gastric cancer prognosis.

Methods

A total of 55 postoperative HER-2-positive gastric cancer patients were included in this study. CLDN 18.2 protein was detected by immunohistochemistry, and detailed clinical and pathological information was collected. Factors considered potentially important in the univariate analysis were included in the multivariate analysis, which involved COX regression to find the independent prognostic factors affecting disease-free survival (DFS).

Results

Immunohistochemistry showed that different levels of CLDN 18.2 protein were expressed in HER-2 positive gastric cancer tissues, and the Chi-square analysis showed that the expression level of CLDN 18.2 was significantly correlated with the lymph node stage. Higher expression levels of CLDN 18.2 were found in patients with lymph node positivity and were associated with poor prognosis in HER-2-positive gastric cancer patients. Gastric cancer patients with low and high expressions of CLDN 18.2 had postoperative median DFS of 38.5 months (95% confidence interval (CI) 28.8-48.2 months) and 12.1 months (95% CI, 11.7-41.0 months), respectively.

Conclusion

High expression of CLDN 18.2 in HER-2 positive gastric cancer is associated with poor prognosis, and the optimal treatment mode for this population is worth exploring after the approval of anti-CLDN 18.2 drugs.

Current challenges and therapeutic advances of CAR-T cell therapy for solid tumors

The application of chimeric antigen receptor (CAR) T cells in the management of hematological malignancies has emerged as a noteworthy therapeutic breakthrough. Nevertheless, the utilization and effectiveness of CAR-T cell therapy in solid tumors are still limited primarily because of the absence of tumor-specific target antigen, the existence of immunosuppressive tumor microenvironment, restricted T cell invasion and proliferation, and the occurrence of severe toxicity. This review explored the history of CAR-T and its latest advancements in the management of solid tumors. According to recent studies, optimizing the design of CAR-T cells, implementing logic-gated CAR-T cells and refining the delivery methods of therapeutic agents can all enhance the efficacy of CAR-T cell therapy. Furthermore, combination therapy shows promise as a way to improve the effectiveness of CAR-T cell therapy. At present, numerous clinical trials involving CAR-T cells for solid tumors are actively in progress. In conclusion, CAR-T cell therapy has both potential and challenges when it comes to treating solid tumors. As CAR-T cell therapy continues to evolve, further innovations will be devised to surmount the challenges associated with this treatment modality, ultimately leading to enhanced therapeutic response for patients suffered solid tumors.

[177Lu]Lu-labeled anti-claudin-18.2 antibody demonstrated radioimmunotherapy potential in gastric cancer mouse xenograft models

PURPOSE

Gastric cancer (GC), one of the most prevalent and deadliest tumors worldwide, is often diagnosed at an advanced stage with limited treatment options and poor prognosis. The development of a CLDN18.2-targeted radioimmunotherapy probe is a potential treatment option for GC.

METHODS

The CLDN18.2 antibody TST001 (provided by Transcenta) was conjugated with DOTA and radiolabeled with the radioactive nuclide 177Lu. The specificity and targeting ability were evaluated by cell uptake, imaging and biodistribution experiments. In BGC823CLDN18.2/AGSCLDN18.2 mouse models, the efficacy of [177Lu]Lu-TST001 against CLDN18.2-expressing tumors was demonstrated, and toxicity was evaluated by H&E staining and blood sample testing.

RESULTS

[177Lu]Lu-TST001 was labeled with an 99.17%±0.32 radiochemical purity, an 18.50 ± 1.27 MBq/nmol specific activity and a stability of ≥ 94% after 7 days. It exhibited specific and high tumor uptake in CLDN18.2-positive xenografts of GC mouse models. Survival studies in BGC823CLDN18.2 and AGSCLDN18.2 tumor-bearing mouse models indicated that a low dose of 5.55 MBq and a high dose of 11.10 MBq [177Lu]Lu-TST001 significantly inhibited tumor growth compared to the saline control group, with the 11.1 MBq group showing better therapeutic efficacy. Histological staining with hematoxylin and eosin (H&E) and Ki67 immunohistochemistry of residual tissues confirmed tumor tissue destruction and reduced tumor cell proliferation following treatment. H&E showed that there was no significant short-term toxicity observed in the heart, spleen, stomach or other important organs when treated with a high dose of [177Lu]Lu-TST001, and no apparent hematotoxicity or liver toxicity was observed.

CONCLUSION

In preclinical studies, [177Lu]Lu-TST001 demonstrated significant antitumor efficacy with acceptable toxicity. It exhibits strong potential for clinical translation, providing a new promising treatment option for CLDN18.2-overexpressing tumors, including GC.

Targeting solid tumor antigens with chimeric receptors: cancer biology meets synthetic immunology

Chimeric antigen receptor (CAR) T cell therapy is a medical breakthrough in the treatment of B cell malignancies. There is intensive focus on developing solid tumor-targeted CAR-T cell therapies. Although clinically approved CAR-T cell therapies target B cell lineage antigens, solid tumor targets include neoantigens and tumor-associated antigens (TAAs) with diverse roles in tumor biology. Multiple early-stage clinical trials now report encouraging signs of efficacy for CAR-T cell therapies that target solid tumors. We review the landscape of solid tumor target antigens from the perspective of cancer biology and gene regulation, together with emerging clinical data for CAR-T cells targeting these antigens. We then discuss emerging synthetic biology strategies and their application in the clinical development of novel cellular immunotherapies.

DR30318, a novel tri-specific T cell engager for Claudin 18.2 positive cancers immunotherapy

BACKGROUND

Claudin 18.2 (CLDN18.2) is a highly anticipated target for solid tumor therapy, especially in advanced gastric carcinoma and pancreatic carcinoma. The T cell engager targeting CLDN18.2 represents a compelling strategy for enhancing anti-cancer efficacy.

METHODS

Based on the in-house screened anti-CLDN18.2 VHH, we have developed a novel tri-specific T cell engager targeting CLDN18.2 for gastric and pancreatic cancer immunotherapy. This tri-specific antibody was designed with binding to CLDN18.2, human serum albumin (HSA) and CD3 on T cells.

RESULTS

The DR30318 demonstrated binding affinity to CLDN18.2, HSA and CD3, and exhibited T cell-dependent cellular cytotoxicity (TDCC) activity in vitro. Pharmacokinetic analysis revealed a half-life of 22.2-28.6 h in rodents and 41.8 h in cynomolgus monkeys, respectively. The administration of DR30318 resulted in a slight increase in the levels of IL-6 and C-reactive protein (CRP) in cynomolgus monkeys. Furthermore, after incubation with human PBMCs and CLDN18.2 expressing cells, DR30318 induced TDCC activity and the production of interleukin-6 (IL-6) and interferon-gamma (IFN-γ). Notably, DR30318 demonstrated significant tumor suppression effects on gastric cancer xenograft models NUGC4/hCLDN18.2 and pancreatic cancer xenograft model BxPC3/hCLDN18.2 without affecting the body weight of mice.

Dark horse target Claudin18.2 opens new battlefield for pancreatic cancer

Pancreatic cancer is one of the deadliest malignant tumors, which is a serious threat to human health and life, and it is expected that pancreatic cancer may be the second leading cause of cancer death in developed countries by 2030. Claudin18.2 is a tight junction protein expressed in normal gastric mucosal tissues, which is involved in the formation of tight junctions between cells and affects the permeability of paracellular cells. Claudin18.2 is highly expressed in pancreatic cancer and is associated with the initiation, progression, metastasis and prognosis of cancer, so it is considered a potential therapeutic target. Up to now, a number of clinical trials for Claudin18.2 are underway, including solid tumors such as pancreatic cancers and gastric cancers, and the results of these trials have not yet been officially announced. This manuscript briefly describes the Claudia protein, the dual roles of Cluadin18 in cancers, and summarizes the ongoing clinical trials targeting Claudin18.2 with a view to integrating the research progress of Claudin18.2 targeted therapy. In addition, this manuscript introduces the clinical research progress of Claudin18.2 positive pancreatic cancer, including monoclonal antibodies, bispecific antibodies, antibody-drug conjugates, CAR-T cell therapy, and hope to provide feasible ideas for the clinical treatment of Claudin18.2 positive pancreatic cancer.

Predictive and prognostic biomarkers in gastrointestinal tract tumours

Tumours of the gastrointestinal tract represent nearly a quarter of all newly diagnosed tumours diagnosed in 2019. Various treatment modalities for gastrointestinal cancers exist, some of which may be guided by biomarkers. Biomarkers act as gauges of either normal or pathogenic processes or responses to an exposure or intervention. They come in many forms. This review explores established and potential molecular/immunohistochemical (IHC) predictive and prognostic biomarkers of the gastrointestinal tract.

Mapping spatial heterogeneity in gastric cancer microenvironment

Gastric cancer (GC) is difficult to characterize due to its heterogeneity, and the complicated heterogeneity leads to the difficulty of precisely targeted therapy. The spatially heterogeneous composition plays a crucial role in GC onset, progression, treatment efficacy, and drug resistance. In recent years, the technological advancements in spatial omics has shifted our understanding of the tumor microenvironment (TME) from cancer-centered model to a dynamic and variant whole. In this review, we concentrated on the spatial heterogeneity within the primary lesions and between the primary and metastatic lesions of GC through the TME heterogeneity including the tertiary lymphoid structures (TLSs), the uniquely spatial organization. Meanwhile, the immune phenotype based on spatial distribution was also outlined. Furthermore, we recapitulated the clinical treatment in mediating spatial heterogeneity in GC, hoping to provide a systematic view of how spatial information could be integrated into anti-cancer immunity.