• Age range from 18 to 80 years old, both male and female;

• Eastern Cooperative Oncology Group Performance Status score 0-2 poinRecurrent or metastatic solid tumors confirmed by pathology (including but not limited to pancreatic cancer, colorectal cancer, lung cancer, liver cancer, cholangiocarcinoma, gastrointestinal stromal tumor, head and neck tumor, gastric cancer, bone and soft tissue sarcoma, neuroendocrine tumor, etc.);

• Malignant pleural/abdominal effusion confirmed by pathology;

• Expected survival time ≥ 12 weeks;

• The main organ function and bone marrow function are normal, meeting the following requirements:

‣ Hemoglobin ≥ 80 g/L (no blood transfusion within 14 days);

⁃ Absolute neutrophil count ≥ 1.5 × 109/L, and white blood cell count ≥ 3 × 109/L;

⁃ Platelet count ≥ 90 × 109/L;

⁃ If there is no liver metastasis, total bilirubin\<1.5 × ULN; If there is liver metastasis or Gilbert syndrome in patients with high indirect bilirubinemia, total bilirubin\<3 × ULN;

⁃ If there is no confirmed liver metastasis, AST and ALT\<2.5 × ULN; If there is confirmed liver metastasis, AST and ALT\<5 × ULN;

⁃ Serum creatinine ≤ 1.5 × The upper limit of normal value (ULN) and the creatinine clearance rate calculated by the Cockroft Fault formula \* are ≥ 30 mL/min;

⁃ Left ventricular ejection fraction (LVEF) ≥ 50%;

⁃ International standardized ratio (INR)\<1.5, and activated partial prothrombin time (APTT)\<1.5 × ULN.

• The interval between previous anti-tumor therapy and the first administration of this trial is ≥ 4 weeks, and the toxicity related to anti-tumor therapy has returned to ≤ 1 level (excluding hair loss, vitiligo, stable hypothyroidism after hormone replacement therapy, etc.);

• Women of childbearing age must undergo a negative pregnancy test (serum or urine) within 14 days before enrollment, and voluntarily use appropriate methods of contraception during the observation period and within 3 months after the last administration of the study drug; For males, surgical sterilization or agreement to use appropriate methods of contraception during observation and within 3 months after the last administration of the study medication should be considered;

• Those who voluntarily participate and sign an informed consent form, and are willing to follow the experimental treatment plan and visit plan;

• Agree to provide blood samples, pleural/ascitic fluid samples, and histological specimens.