Intraperitoneal PD-1 monoclonal antibody for the treatment of advanced primary liver cancer with malignant ascites: a single-arm, single-center, phase Ib trial.

Background: Advanced primary liver cancer patients with malignant ascites have a poor prognosis and lack effective treatment plans. This phase Ib study aims to explore the safety and clinical efficacy of intraperitoneal anti-programmed cell death protein 1 (PD-1) antibody in these patients.

Patients And Methods: Patients received sintilimab 100 mg intraperitoneally plus best supportive care on days 1, 8, and 15 in three cycles of 4 weeks. The course was repeated every 28 days until intolerable toxicity had developed or disease progression. The primary endpoint was safety, while the secondary endpoints were objective response rate (ORR), ascites control rate (ACR), and overall survival (OS).

Results: From February 2021 through November 2022, a total of 21 patients (14 hepatocellular carcinoma and 7 cholangiocarcinoma) were enrolled to receive intraperitoneal sintilimab. Twelve patients had adverse events (AEs). The most common grade 3 AEs were fatigue, rash, and abdominal pain. No grade ≥4 AEs occurred in any patients. ORR was only evaluated in 13 patients, including partial response in 4, stable disease in 7, and progressive disease in 2. A reduction in the median maximum diameter of the tumor after treatment was observed; however, there was no statistical significance among patients. The objective remission rate of ascites was 43.75%, and the median OS for all 21 patients was 17.6 weeks.

Conclusions: This exploratory study represents the first trial to demonstrate the safety and clinical efficacy of intraperitoneal anti-PD-1 antibody administration. No unexpected safety concerns were identified. A large, multicenter, prospective study is needed to confirm the promising clinical efficacy.