Zolbetuximab combined with chemotherapy in a patient with CLDN18.2-positive advanced gastric cancer undergoing hemodialysis: a case report.

Background: Despite meaningful advances in systemic therapy, the prognosis of patients with unresectable advanced or metastatic gastric cancer remains poor. Targeted and immunotherapeutic approaches benefit only selected subpopulations, while the majority of patients continue to lack effective treatment options. Claudin 18.2 (CLDN18.2) has recently emerged as a promising therapeutic target, and the CLDN18.2-targeted monoclonal antibody zolbetuximab has demonstrated clinically meaningful efficacy in multiple international clinical trials. However, evidence for its use in patients with severe renal impairment requiring maintenance hemodialysis is lacking. In this population, conventional chemotherapy is often limited by altered pharmacokinetics and the risk of heightened toxicity, highlighting an important unmet clinical need. Case summary: We report the case of a 46-year-old woman with metastatic CLDN18.2-positive, HER2-negative gastric adenocarcinoma who subsequently developed end-stage renal disease (ESRD) secondary to tumor progression, necessitating regular hemodialysis. Following multidisciplinary evaluation, irinotecan combined with zolbetuximab was initiated on the basis of individualized adjustment of the hemodialysis schedule. The regimen was well tolerated, associated with stabilization of renal function, and resulted in a marked decline in serum CA19-9 accompanied by a significant shrinkage of peritoneal metastatic lesions on CT imaging, with sustained disease control during treatment. Conclusion: This case highlights that in patients with advanced gastric cancer undergoing hemodialysis, CLDN18.2-targeted therapy combined with chemotherapy may be feasible and safe with close laboratory monitoring and individualized dialysis management and may serve as a valuable reference for personalized treatment in gastric cancer complicated by renal failure.