Inclusion Criteria:
* Aged ≥18 years old, gender unrestricted.
* Histologically or cytologically confirmed malignant peritoneal effusion derived from digestive system tumors (malignancy confirmed by ascites cytology, or peritoneal metastases diagnosed clinically based on imaging findings and symptoms).
* Moderate to large volume of peritoneal effusion, with failure of initial treatment or previous intraperitoneal therapy with conventional chemotherapeutic agents and/or biological response modifiers. Moderate volume of ascites is defined as: ①Ascites depth ≥3 cm confirmed by supine abdominal ultrasound; ② Presence of clinical symptoms (chest distress, dyspnea, abdominal distension and discomfort) judged by the investigator to be related to peritoneal effusion.
* ECOG performance status score 0-2.
* Expected survival time \>3 months.
* Essentially normal cardiopulmonary function.
* Adequate organ function, with subjects required to meet the following laboratory parameters:
1. Peripheral blood count: WBC ≥4.0×10⁹/L, PLT ≥80×10⁹/L, Hb ≥90 g/L.
2. Renal function: Serum creatinine ≤2×ULN and creatinine clearance rate (calculated by the Cockcroft-Gault formula) ≥40 ml/min.
3. Hepatic function: Total bilirubin ≤1.5×ULN; or total bilirubin \>ULN with direct bilirubin ≤ULN. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤2.5×ULN (for patients with liver metastases, ALT or AST ≤5×ULN is acceptable).
4. Adequate coagulation function, defined as international normalized ratio (INR) or prothrombin time (PT) ≤1.5×ULN.
* Thyroid stimulating hormone (TSH) ≤ULN. If TSH is abnormal, serum triiodothyronine (T3) and thyroxine (T4) levels, together with clinical manifestations, shall be evaluated comprehensively; subjects in non-acute active phase are eligible for enrollment.
* For non-surgically sterilized subjects of childbearing potential or female subjects of childbearing potential: A medically approved contraceptive method (e.g., intrauterine device, oral contraceptives, or condoms) must be used during the study treatment period and for 6 months after the end of study treatment. For non-surgically sterilized female subjects of childbearing potential, serum or urine HCG test must be negative within 7 days prior to enrollment, and they must be non-lactating. For male subjects whose partners are women of childbearing potential, effective contraceptive measures must be adopted during the trial and for 6 months after the last administration of the study drug.
* Voluntarily participate in the study with good compliance, sign a written informed consent form, and be able to cooperate with follow-up assessments.
Exclusion Criteria:
* History of hypersensitivity to tumor necrosis factor (TNF), its derivative drugs, bevacizumab or its analogs, irinotecan, or liposomal irinotecan.
* Diagnosis of malignant diseases other than gastrointestinal tumors within 5 years prior to the first dose (excluding radically treated basal cell carcinoma of the skin, cutaneous squamous cell carcinoma, and/or radically resected carcinoma in situ).
* Receipt of any other investigational drug treatment or participation in an interventional clinical trial within 7 days prior to the first dose; or receipt of anti-tumor therapy (including Chinese herbal medicines with anti-tumor indications) within 7 days prior to the first dose of the study drug.
* Pregnant or lactating women; women of childbearing potential who are unwilling to take contraceptive measures during the study period; or men who are unwilling to use effective contraceptive measures during treatment and for 1 year thereafter.
* Significant impairment of major organ function.
* Patients with obvious bleeding tendency.
* Clinically significant or uncontrolled cardiac diseases, including unstable angina pectoris, acute myocardial infarction within 6 months prior to the first dose, New York Heart Association (NYHA) Class III/IV congestive heart failure, and uncontrolled arrhythmias (subjects with pacemakers or atrial fibrillation with well-controlled heart rate are permitted).
* Clinically significant ECG abnormalities or relevant medical history as judged by the investigator; screening QTcF interval \> 480 ms. For subjects with intraventricular conduction block (QRS interval \> 120 ms), JTc interval may be used instead of QTc interval (if JTc is used, it must be ≤ 340 ms).
* Uncontrolled hypertension, defined as systolic blood pressure \> 160 mmHg or diastolic blood pressure \> 100 mmHg despite optimal medical treatment; a history of hypertensive crisis or hypertensive encephalopathy.
* Severe acute infection that is uncontrolled; current fever (\> 38℃), purulent or chronic infection, or unhealed wounds.
* Patients with radiologically confirmed loculated peritoneal effusion; definitely diagnosed peritoneal infection.
* Active acute or chronic hepatitis B or C infection, with hepatitis B virus (HBV) DNA \> 2000 IU/mL or 10⁴ copies/mL; hepatitis C virus (HCV) RNA \> 10³ copies/mL; concurrent positivity for hepatitis B surface antigen (HBsAg) and anti-HCV antibody. Subjects who have received nucleoside analog antiviral therapy and achieved viral load below the above thresholds are eligible for enrollment. A known history of human immunodeficiency virus (HIV) infection or confirmed positive HIV test results.
* Evidence or history of obvious bleeding tendency within 3 months prior to enrollment (bleeding \> 30 mL within 3 months, hematemesis, melena, hematochezia); hemoptysis (\> 5 mL of fresh blood within 4 weeks); a history of hereditary or acquired bleeding disorders or coagulation dysfunction. Clinically significant bleeding symptoms or definite bleeding tendency within 3 months prior to enrollment (e.g., gastrointestinal bleeding, hemorrhagic gastric ulcer).
* A history of arterial or venous thrombotic disease within 6 weeks prior to enrollment.
* A known history of allogeneic organ transplantation or allogeneic hematopoietic stem cell transplantation.
* Receipt of major surgery (craniotomy, thoracotomy, or laparotomy) within 4 weeks prior to the first dose of study treatment, or anticipated need for major surgery during the study treatment period.
* Failure to achieve adequate recovery from toxicity and/or complications of major surgery prior to the start of treatment.
* Pregnant or lactating women; or subjects who plan to conceive or give birth during the study period from screening visit to completion of safety follow-up visit (90 days after the last dose for male subjects).
* Receipt of radiotherapy within 4 weeks prior to the first dose of study drug.
* Radiotherapy-related toxicities in subjects must have fully resolved, without the need for corticosteroid therapy, and radiation pneumonitis must be definitely excluded. For palliative radiotherapy for non-central nervous system (CNS) diseases, a 2-week washout period is permitted.
* Uncontrolled neurological or psychiatric diseases/disorders with poor compliance, resulting in inability to cooperate or report treatment responses. Uncontrolled primary brain tumors or central nervous system metastases with obvious intracranial hypertension or neuropsychiatric symptoms.
* Other conditions that, in the investigator's judgment, make the subject unsuitable for participation in this trial.
