Intraperitoneal nivolumab for malignant ascites in patients with advanced gastrointestinal or pancreaticobiliary tract cancer

Sep 23, 2026

Malignant ascites affect 10–15% of patients with gastrointestinal cancers, where peritoneal and ascitic immune cells coexist with a cancer-driven immunosuppressive milieu. The study evaluated intraperitoneal nivolumab to control malignant ascites by delivering 20 mg nivolumab in 100 mL saline into the peritoneal cavity after paracentesis, with repeated cycles until inefficacy, unacceptable toxicity, or patient request. Nine cytology-confirmed patients were treated. Seven (77.8%) showed clinical response with reduced ascites and longer paracentesis intervals, accompanied by minimal toxicity.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages11

Reading Time28 min

AccessFree to download

Abstract

Background

Methods

Results

Conclusion

Introduction

Incidence and mechanisms of malignant ascites

Current management options

Peritoneal immunology

International Journal of Clinical Oncology (2026) 31:281–291 [https://doi.org/10.1007/s10147-025-02930-y](https://doi.org/10.1007/s10147-025-02930-y) Intraperitoneal nivolumab for malignant ascites in patients with advanced gastrointestinal or pancreaticobiliary tract cancer Hsiu‑Tzu Wang1,2 · Yung‑Luen Yu2,3,4,5 · Wen‑Jyi Lo1 · Mei‑Chen Lin1 · Chien‑Lun Chu6 · Chia‑Yu Chen1 · Sing‑Ting Wang1 · Chang‑Fang Chiu1,6,7 · En‑Jia Bai8 · Li‑Yuan Bai1,7 Received: 13 July 2025 / Accepted: 20 November 2025 / Published online: 10 December 2025 © The Author(s) 2025 Abstract Background Malignant ascites occur in 10–15% of patients with gastrointestinal tract cancers. The abundance of immune cells in the peritoneum and ascitic fluid, along with the immunosuppressive environment created by cancer cells, suggests the potential utility of intraperitoneal (IP) immune checkpoint inhibitors for controlling malignant ascites. Methods Patients with gastrointestinal or pancreaticobiliary tract cancer and cytologically confirmed malignant ascites received IP nivolumab. Twenty mg of nivolumab diluted in 100 mL of saline was infused into the peritoneal cavity over 10 min following paracentesis. IP treatment was repeated after each subsequent paracentesis until deemed ineffective by the treating physician, upon the occurrence of unacceptable toxicity, or discontinued at the patient’s request. This study was [registered at ClinicalTrials.gov](registered at ClinicalTrials.gov) (NCT05745233). Results The median age of the nine enrolled patients was 55 years. Underlying malignancies included pancreatic (n = 4), biliary tract (n = 3), and gastric cancers (n = 2) . After a median of 3 (range: 2–5) treatment cycles, seven patients (77.8%) showed a clinical response, as evidenced by reduced ascitic fluid and prolonged intervals between paracenteses. The only adverse effect observed was grade 1 tenderness at the puncture sites. Reduction in tumor cell count in ascites, rather than changes in the total lymphocyte count or lymphocyte subpopulations, correlated with clinical response. Responders consistently exhibited increased vascular endothelial growth factor A and decreased interleukin-1α levels following nivolumab administration. Conclusion Intraperitoneal administration of nivolumab effectively controlled malignant ascites with minimal adverse effects. However, further validation in a larger cohort is required. Keywords Malignant ascites · Gastrointestinal · Pancreaticobiliary · Intraperitoneal · Nivolumab · Cytokines Hsiu-Tzu Wang and Yung-Luen Yu are co-first authors. * Li-Yuan Bai[lybai6@gmail.com](lybai6@gmail.com) 1 Division of Hematology and Oncology, Department of Internal Medicine, China Medical University Hospital, 2, Yude road, North district, Taichung 404327, Taiwan 2 Institute of Translational Medicine and New Drug Development, China Medical University, Taichung 406040, Taiwan 3 Graduate Institute of Biomedical Sciences, China Medical University, Taichung 406040, Taiwan 4 Center for Molecular Medicine, China Medical University Hospital, Taichung 404327, Taiwan 5 Department of Medical Laboratory Science and Biotechnology, Asia University, Taichung 413305, Taiwan 6 Cancer Center, China Medical University Hospital, Taichung 404327, Taiwan 7 College of Medicine, School of Medicine, China Medical University, Taichung 406404, Taiwan 8 Bachelor of Science in Kinesiology, Exercise Science, The University of Texas at Austin, Austin, TX 78712, USA Introduction Malignant ascites develop in 10–15% of patients with gastrointestinal cancers at some stage of the disease [1], including 8–18.3% of patients with gastric cancer [2, 3], 15–21% of those with advanced pancreaticobiliary cancers [3 , 4], and approximately 4.0% of patients with esophageal cancer. Several factors contribute to the formation of malignant ascites, including obstruction of lymphatic drainage by tumor cells, altered vascular permeability, hormonal

FAQs

What rationale supports using intraperitoneal nivolumab for malignant ascites?

The peritoneum and ascitic fluid contain abundant immune cells, yet the tumor microenvironment is immunosuppressive. Intraperitoneal immune checkpoint inhibition is intended to counter this to control ascites.

How was intraperitoneal nivolumab administered in the study?

Patients received 20 mg nivolumab diluted in 100 mL saline infused into the peritoneal cavity over 10 minutes after paracentesis. Treatment was repeated after subsequent paracenteses until ineffective, unacceptable toxicity occurred, or it was stopped at the patient’s request.

What were the main outcomes and safety findings?

Seven of nine patients (77.8%) achieved clinical response after a median of 3 cycles, shown by reduced ascitic fluid and prolonged intervals between paracenteses. The only observed adverse effect was grade 1 tenderness at puncture sites.

Sep 23, 2026

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