Phase 1 trial of zolbetuximab in Japanese patients with CLDN18.2+ gastric or gastroesophageal junction adenocarcinoma

Claudin 18.2 Immunohistochemistry Expression in Gastric Cancer: A Systematic Review

Claudin 18.2 is a transmembrane protein, part of the tight-junction complex, selectively expressed in gastric epithelium. It is showing promising results as a target in advanced gastric cancer in phase 3 clinical trials using a monoclonal antibody against claudin 18.2. A systematic review on expression of claudin 18.2 in gastric cancer was performed using the PubMed database. The following search expression was used: ("Stomach Neoplasms" [Mesh]) AND (("claudin-18[TIAB]") OR ("CLDN18[TIAB]")). A total of n=99 articles were retrieved. Of those, 17 preclinical studies about claudin 18.2 expression by immunohistochemistry were selected. The results of those studies showed great variability in the criteria used for defining the thresholds for positivity of the stain. The proportion of claudin 18.2 positive cases varied between 24% and 83%. In works using a positivity threshold set at >40% or >70% of cells with membranous/cytoplasmic staining at 2+/3+ intensity, the average rate of positive cases was 50% or 30%, respectively (similar with clones 43-14A and EPR19202). Positivity of claudin 18.2 was associated with advanced stage, diffuse phenotype and PD-L1 and EBV positivity in some of the studies. Variability in criteria used to define claudin 18.2 positivity, as well as methodological differences, could explain the variation in the proportion of positive cases described, as well as the inconsistency of the association with clinical, molecular, and survival variables. The upcoming anticlaudin 18.2 therapy in advanced gastric cancer should prompt pathology laboratories to adjust their staining protocols and evaluation criteria in their series of patients, to further establish the association of claudin expression with clinical and molecular variables.

Claudin 18.2-targeting antibody-drug conjugate CMG901 in patients with advanced gastric or gastro-oesophageal junction cancer (KYM901): a multicentre, open-label, single-arm, phase 1 trial

BACKGROUND

CMG901 is a novel first-in-class antibody-drug conjugate with a humanised anticlaudin 18.2 antibody linked to microtubule-disrupting agent monomethyl auristatin E. We aimed to assess the antitumour activity and safety of CMG901 in patients with advanced gastric or gastro-oesophageal junction cancer and other solid tumours.

METHODS

KYM901 is a multicentre, open-label, single-arm, phase 1 trial consisting of dose-escalation and dose-expansion stages. Patients with advanced solid tumours, including gastric or gastro-oesophageal junction and pancreatic cancers, were recruited from 31 hospital sites in China. Eligible patients were aged 18 years or older, were refractory to standard therapy or had no available standard-of-care regimen, and had an Eastern Cooperative Oncology Group performance status score of 0-1, a life expectancy of at least 3 months, and at least one measurable lesion. Patients received intravenous CMG901 every 3 weeks (0·3-3·4 mg/kg in dose escalation and 2·2-3·0 mg/kg in dose expansion) until disease progression, unacceptable toxic effects, initiation of new antitumour therapy, study withdrawal, or death. Primary endpoints were adverse events and dose-limiting toxic effects in the dose-escalation phase, and objective response rate and recommended phase 2 dose in the dose-expansion phase. Confirmed objective response was defined as a partial or complete response that was verified by follow-up imaging at least 4 weeks after the initial assessment. Safety was assessed in all patients who received at least one dose of CMG901 with at least one post-dose safety evaluation. Antitumour activity was assessed in all patients who received at least one dose of CMG901 (full analysis set) and in all CMG901-treated patients with at least one post-dose imaging evaluation and no major protocol deviations (efficacy analysis set). Dose-expansion data for patients with pancreatic cancer will be published separately. Due to small sample sizes, results in patients with other solid tumours (n=2) are not planned for publication. This ongoing trial is registered with ClinicalTrials.gov, NCT04805307.

FINDINGS

Between Dec 24, 2020, and Feb 23, 2023, 27 patients were enrolled in the dose-escalation phase (median age 57·0 years [IQR 48·0-63·0]; 14 [52%] male, 13 [48%] female) and 107 patients with gastric or gastro-oesophageal junction cancer in the dose-expansion phase (median age 56·0 years [44·0-64·0]; 57 [53%] male, 50 [47%] female). As of Feb 24, 2024, one dose-limiting toxic effect (grade 3 pancreatitis) occurred at 2·2 mg/kg, and the maximum tolerated dose was not reached in the dose-escalation phase. All 27 patients reported at least one treatment-emergent adverse event, most frequently vomiting (19 [70%]), decreased appetite (16 [59%]), proteinuria (16 [59%]), and anaemia (15 [56%]), and five (19%) had drug-related grade 3 or worse treatment-emergent adverse events. In 107 patients, grade 3 or worse treatment-emergent adverse events occurred in 73 (68%) patients and serious adverse events occurred in 54 (50%) patients in dose expansion. The most common grade 3-4 adverse events were neutrophil count decreased (22 [21%]), anaemia (15 [14%]), and vomiting (11 [10%]). One treatment-related death was reported. At median follow-up of 9·0 months (IQR 4·4-12·9), among 113 patients with gastric or gastro-oesophageal junction cancer in the 2·2-3·0 mg/kg cohort full analysis set across both the dose-escalation and dose-expansion phases, the confirmed objective response rate was 28% (95% CI 20-38; 32 of 113 patients). In the 109 patients included in the efficacy analysis set, the confirmed objective response rate was 29% (95% CI 21-39; 32 of 109 patients). Based on overall safety, activity, and pharmacokinetics of CMG901, 2·2 mg/kg was the proposed recommended phase 2 dose.

INTERPRETATION

CMG901 showed a manageable safety profile and had promising antitumour activity in patients with advanced gastric or gastro-oesophageal junction cancer.

FUNDING

KYM Biosciences.

Zolbetuximab for Unresectable and Metastatic Gastric and Gastroesophageal Junction Adenocarcinoma: A Review of Literature

This article comprehensively reviews the working, efficacy, and safety profile of zolbetuximab. Zolbetuximab is a pioneering chimeric monoclonal antibody designed to target Claudin 18.2 (CLDN18.2), a tight junction protein frequently overexpressed in various gastrointestinal cancers, including gastric (G) and gastroesophageal junction (GEJ) adenocarcinomas. This drug has captured attention in the treatment of unresectable and metastatic G/GEJ cancer, especially in HER2-negative patients whose tumours express CLDN18.2. Zolbetuximab is a drug that binds to CLDN18.2, and its binding initiates an immune response that attacks and kills the cancer cells. It is typically co-prescribed with fluoropyrimidine and platinum-containing chemotherapy. The drug (formerly IMAB362), brand name Vyloy, was developed by Astellas Pharma, Tokyo, Japan. After multiple rounds of clinical trials, it was approved by the U.S. Food and Drug Administration (FDA) as a first-line treatment for locally advanced, unresectable cancer, establishing itself as a promising option for advanced G/GEJ cancers. Studies reveal that it targets CLDN18.2 for the selective killing of cancer cells while sparing most healthy tissues. Zolbetuximab has demonstrated a significant improvement in progression-free survival (PFS) when combined with chemotherapy (like mFOLFOX6 or CAPOX). Also, it showed prolonged PFS compared to chemotherapy alone in previously untreated, CLDN18.2-positive, HER2-negative patients. Zolbetuximab has also shown improvements in overall survival (OS), regardless of whether the cancer progresses. This is a crucial benefit for patients with advanced G/GEJ adenocarcinomas. Additionally, zolbetuximab's dual action triggers antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). This enhances the immune system's ability to destroy cancerous cells and results in highly potent tumour destruction compared with chemotherapy alone. Zolbetuximab is a relatively safe drug with a few adverse effects. The most frequently reported side effects were gastrointestinal, namely nausea, fatigue, vomiting, decreased appetite, diarrhea, neutropenia, anemia, and thrombocytopenia, potentially due to specific CLDN18.2 expression in the gastric mucosa. Its side effects are generally manageable, with no unexpected toxicity beyond those typically seen in patients receiving chemotherapy.

Targeting esophageal carcinoma: molecular mechanisms and clinical studies

Esophageal cancer (EC) is identified as a predominant health threat worldwide, with its highest incidence and mortality rates reported in China. The complex molecular mechanisms underlying EC, coupled with the differential incidence of esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC) across various regions, highlight the necessity for in-depth research targeting molecular pathogenesis and innovative treatment strategies. Despite recent progress in targeted therapy and immunotherapy, challenges such as drug resistance and the lack of effective biomarkers for patient selection persist, impeding the optimization of therapeutic outcomes. Our review delves into the molecular pathology of EC, emphasizing genetic and epigenetic alterations, aberrant signaling pathways, tumor microenvironment factors, and the mechanisms of metastasis and immune evasion. We further scrutinize the current landscape of targeted therapies, including the roles of EGFR, HER2, and VEGFR, alongside the transformative impact of ICIs. The discussion extends to evaluating combination therapies, spotlighting the synergy between targeted and immune-mediated treatments, and introduces the burgeoning domain of antibody-drug conjugates, bispecific antibodies, and multitarget-directed ligands. This review lies in its holistic synthesis of EC's molecular underpinnings and therapeutic interventions, fused with an outlook on future directions including overcoming resistance mechanisms, biomarker discovery, and the potential of novel drug formulations.

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.

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.

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.

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.

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.

Exploration of radionuclide labeling of a novel scFv-Fc fusion protein targeting CLDN18.2 for tumor diagnosis and treatment

PURPOSE

Claudin 18.2 (CLDN18.2), due to its highly selective expression in tumor cells, has made breakthrough progress in clinical research and is expected to be integrated into routine tumor diagnosis and treatment.

METHODS

In this research, we obtained an scFv-Fc fusion protein (SF106) targeting CLDN18.2 through hybridoma technology. The scFv-Fc fusion protein was labeled with radioactive isotopes (124I and 177Lu) to generate the radio-probes. The targeting and specificity of the radio-probes were tested in cellular models, and its diagnostic and therapeutic potential was further evaluated in tumor-bearing models.

RESULTS

The molecular probes [124I]I-SF106 and [177Lu]Lu-DOTA-SF106 possess high radiochemical purity (RCP, 98.18 ± 0.93 % and 97.05 ± 1.1 %) and exhibit good stability in phosphate buffer saline and 5 % human serum albumin (92.44 ± 4.68 % and 91.03 ± 2.42 % at 120 h). [124I]I-SF106 uptake in cells expressing CLDN18.2 was well targeted and specific, and the dissociation constant was 17.74 nM [124I]I-SF106 micro-PET imaging showed that the maximum standardized uptake value (SUVmax) was significantly higher than CLDN18.2-negative tumors (1.83 ± 0.02 vs. 1.23 ± 0.04, p < 0.001). The maximum uptake was attained in tumors expressing CLDN18.2 at 48 h after injection. [124I]I-SF106 and [177Lu]Lu-DOTA-SF106 dosimetric study showed that the effective dose in humans complies with the medical safety standards required for their clinical application. The results of treatment experiments showed that 3 MBq of [177Lu]Lu-DOTA-SF106 in CLDN18.2-expressing tumor-bearing mice could significantly inhibit tumor growth.

CONCLUSION

These results indicate that radionuclide-labeled scFv-Fc molecular probes ([124I]I-SF106 and [177Lu]Lu-DOTA-SF106) provide a new possibility for the diagnosis and treatment of CLDN18.2-positive cancer patients in clinical practice.

Antibody-mediated targeting of Claudins in cancer

Tight junctions (TJs) are large intercellular adhesion complexes that maintain cell polarity in normal epithelia and endothelia. Claudins are critical components of TJs, forming homo- and heteromeric interaction between adjacent cells, which have emerged as key functional modulators of carcinogenesis and metastasis. Numerous epithelial-derived cancers display altered claudin expression patterns, and these aberrantly expressed claudins have been shown to regulate cancer cell proliferation/growth, metabolism, metastasis and cell stemness. Certain claudins can now be used as biomarkers to predict patient prognosis in a variety of solid cancers. Our understanding of the distinct roles played by claudins during the cancer progression has progressed significantly over the last decade and claudins are now being investigated as possible diagnostic markers and therapeutic targets. In this review, we will summarize recent progress in the use of antibody-based or related strategies for targeting claudins in cancer treatment. We first describe pre-clinical studies that have facilitated the development of neutralizing antibodies and antibody-drug-conjugates targeting Claudins (Claudins-1, -3, -4, -6 and 18.2). Next, we summarize clinical trials assessing the efficacy of antibodies targeting Claudin-6 or Claudin-18.2. Finally, emerging strategies for targeting Claudins, including Chimeric Antigen Receptor (CAR)-T cell therapy and Bi-specific T cell engagers (BiTEs), are also discussed.

Efficacy and safety of zolbetuximab for first-line treatment of advanced Claudin 18. 2-positive gastric or gastro-esophageal junction adenocarcinoma: a systematic review and meta-analysis of randomized controlled trials

Objective

Zolbetuximab is a "first-in-class" chimeric lgG1 monoclonal antibody targeting Claudin18.2 (CLDN 18.2). In recent years, several important trials have been published showing that zolbetuximab is associated with improved prognosis in patients with advanced gastric or gastro-esophageal junction (G/GEJ) adenocarcinoma. This promises great change to the current treatment landscape. Therefore, we conducted a systematic review and meta-analysis to evaluate the efficacy and safety of zolbetuximab for first-line treatment of advanced CLDN 18. 2-positive G/GEJ adenocarcinoma.

Methods

The following databases were searched for relevant studies: PubMed, EMBASE, and Cochrane library (updated 10 June 2023). All randomized trials comparing zolbetuximab plus chemotherapy versus first-line chemotherapy alone for first-line treatment of advanced CLDN 18. 2-positive G/GEJ adenocarcinoma were eligible for inclusion. Data were analyzed using Review Manager 5.4.1 (Cochrane collaboration software). Primary outcomes and measures included overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and adverse events (AEs).

Results

This systematic review and meta-analysis included three randomized controlled studies involving 1,402 patients (699 receiving zolbetuximab plus chemotherapy and 703 receiving chemotherapy alone). Compared with chemotherapy alone, zolbetuximab plus chemotherapy significantly improved OS (HR = 0.73; 95% CI: 0.68-0.84) and PFS (HR = 0.64; 95% CI: 0.50-0.82), but did not result in a higher ORR (RR = 0.92; 95% CI: 0.82-1.03). Further analysis of CLDN 18.2 expression showed a more significant benefit for OS (HR = 0.69; 95% CI: 0.55-0.87; p = 0.002) and PFS (HR = 0.61; 95% CI: 0.44-0.84; p = 0.003) from zolbetuximab in patients with high expression, while there was significant benefit in patients with lower expression. In terms of AEs, zolbetuximab plus chemotherapy was associated with higher risk of grade 3 and higher AEs, but increased risk of nausea and vomiting were more common.

Conclusion

This systematic review and meta-analysis revealed that the effect of zolbetuximab plus chemotherapy was superior to that of chemotherapy alone for first-line treatment of advanced CLDN 18.2-positive G/GEJ adenocarcinoma. Thus, zolbetuximab plus chemotherapy represents a new first-line treatment for these patients. Zolbetuximab plus chemotherapy was associated with higher risk of grade 3 and higher AEs, but was generally manageable.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero, identifier (CRD42023437126).