IP rmhTNF-NC + Tislelizumab + Palliat RT for GIT Tumor Malignant Ascites After Failed Std Tx

This study is a prospective, non-randomized, dual-cohort Phase II clinical trial designed to explore the efficacy and safety of radiotherapy combined with intraperitoneal injection of Recombinant Mutant Human Tumor Necrosis Factor (rmhTNF-NC) and tislelizumab in the treatment of malignant ascites that has failed prior standard therapy. After completing the informed consent process, eligible patients who meet the inclusion criteria will be enrolled. Participants will receive palliative radiotherapy combined with intraperitoneal perfusion of rmhTNF-NC and tislelizumab according to the study protocol. Before and after one cycle of treatment, abdominal ultrasound will be used to evaluate the response rate of ascites. Safety assessments will be conducted using NCI-CTCAE v5.0.