This study presents a case of Claudin18.2-positive advanced gastric adenocarcinoma with peritoneal metastasis treated with a multimodal regimen: HIPEC, systemic CapeOx chemotherapy, and Claudin18.2-targeted therapy (ASKB589)...At 893 days post-diagnosis, the patient remains disease-free (PFS/DFS: 893/573 days) on adjuvant capecitabine...However, the absence of cytoreductive surgery and single-case limitations necessitate validation through randomized trials. Future research should prioritize biomarker-driven HIPEC protocols (e.g., nanoparticle-enhanced Claudin18.2-targeted delivery) and dynamic monitoring of Claudin18.2 expression during therapy.

Zolbetuximab is associated with high rates of nausea and vomiting during the initial infusion, whereas ICIs are associated with risk of later-onset immune-related toxicities that can be fatal in rare cases. In considering the available evidence, our opinion is that zolbetuximab is a reasonable option for initial targeted treatment in HER2-/CLDN18.2-positive advanced G/GEJ when PD-L1 CPS score is <10 based on the reliability of biomarker testing, comparable OS, and avoidance of potentially irreversible ICI-induced immune toxicity.

Clinicians should monitor albumin levels during treatment and consider nutritional support when indicated. These findings provide important insights for optimizing patient management and ensuring safe conversion surgery planning.

P1, N=25, Recruiting, Astellas Pharma Global Development, Inc. | Initiation date: Jul 2025 --> Oct 2025

Serial PET imaging with 89Zr-labeled zolbetuximab, an anti-CLDN18.2 monoclonal antibody ([89Zr]Zr-DFO-zolbetuximab), and human IgG ([89Zr]Zr-DFO-IgG) as control (5.5-7.4 MBq) was performed 1, 3, and 6 d after injection, followed by ex vivo analysis of biodistribution... CLDN18.2 could serve as a promising biomarker for precise quantitative imaging and effective treatment of GCa and PDAC. This proof-of-concept study encourages the clinical translation of CLDN18.2 as a radiotheranostic in patients with CLDN18.2-expressing tumors.

P1, N=12, Active, not recruiting, Astellas Pharma Global Development, Inc. | Recruiting --> Active, not recruiting

This review examines the mechanisms, safety profiles, and clinical trial outcomes of three targeted agents-bemarituzumab, zolbetuximab, and ramucirumab-which inhibit tumor growth through the FGFR2b, CLDN18.2, and VEGFR2 pathways, respectively. We also compare traditional versus adaptive clinical trial designs, explore emerging challenges such as therapeutic resistance and treatment-related toxicities, and consider implications for personalized medicine. Collectively, these agents represent a paradigm shift from empiric chemotherapy toward biomarker-driven immunotherapy, with the potential to significantly improve survival and quality of life in patients with advanced G/GEJ cancers.

However, GI toxicities are reported from clinical use of both Zolbetuximab and CT041...We also demonstrate and characterize on-target/off-tumor gastric toxicity targeting CLDN18.2 in a preclinical mouse model of CT041-scFv derived CAR T cell therapy. By developing CLDN18.2 fully-human VH-only single domain CARs, we demonstrate that on-target/off-tumor toxicity inversely correlates with affinity of the binder, and that a lower affinity CAR may widen the therapeutic window for CLDN18.2 by decreasing on-target/off-tumor toxicity while preserving efficacy.

P2, N=143, Active, not recruiting, Astellas Pharma Global Development, Inc. | Trial completion date: Feb 2027 --> May 2027 | Trial primary completion date: Jan 2026 --> Jul 2026

Early-onset transient gastritis frequently occurred following zolbetuximab-containing therapy and was significantly associated with anorexia and hypoalbuminemia. A deeper understanding of gastritis underlying unique GI toxicities may provide insight into effective management.

P3, N=507, Active, not recruiting, Astellas Pharma Global Development, Inc. | Trial completion date: Sep 2025 --> Mar 2026