AUTHOR=Liu Jinlu , Jiang Dan , Lei Qingqiang , Zhu Qing , Zhu Hong 

TITLE=Case Report: A rare case of recurrent ascites after anti-Claudin18.2 antibody therapy for metastatic gastric cancer while responding sustainingly

JOURNAL=Frontiers in Oncology

VOLUME=Volume 13 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2023.1211668

DOI=10.3389/fonc.2023.1211668

ISSN=2234-943X

ABSTRACT=Background
Gastric cancer remains one of the deadliest malignancies in the world, which thus 
demands effective and safe therapeutics urgently. Claudin18.2 is a member of the tight 
junction protein family specifically expressed in gastric cancer cells. Monoclonal 
antibodies targeted to Claudin18.2 are receiving more and more attention recently. 
ASKB589 is a humanized monoclonal antibody targeting Claudin18.2.
Case Presentation
This case described a 65-year-old Chinese male diagnosed with gastric cancer 
metastasizing to the liver and multiple lymph nodes. The biomarker examination 
revealed that he was proficient mismatch repair(pMMR) and human epidermal growth 
factor receptor 2(HER2)was negative and the combined proportion score(CPS) of PD-L1(22C3) was 1. After proven to be moderately positive for Claudin18.2 expression, he 
received the treatment of ASKB589 and CAPOX(oxaliplatin and capecitabine) 
chemotherapy. After 6-cycle therapy(from 2022-7-14 to 2022-11-29), the target tumor 
was evaluated for partial response(PR) by the investigator based on the enhanced CT 
scan according to the Response Evaluation Criteria in Solid Tumors(RECIST) 1.1 
Criteria. However, this patient also suffered from intolerable ascites gradually 
aggravating during the therapy which cannot be well controlled by the supporting 
therapy. Therefore, the patient was stopped receiving the combined therapy in our 
hospital and did not receive other anti-tumor treatment anymore. After 4 months of 
discontinuation of the drug, the patient's ascites almost disappeared, while the tumor 
continued to reduce and almost achieved clinically complete relapse(cCR) and his 
progress-free survival(PFS) reached at least 10 months.
Conclusion
This is the first case of severe ascites reported after anti-Claudin 18.2 monoclonal 
antibody treatment for advanced gastric cancer. At the same time, the patient still 
benefited significantly from this incomplete treatment even after discontinuation of the 
drug and the PFS reached at least 10 months. The ascites might be an immune adverse 
effect related to the monoclonal antibody-induced antibody-dependent cytotoxicity 
(ADCC) and complement-dependent cytotoxicity(CDC). The further mechanism 
remains to be investigated