The goal of this clinical trial is to determine whether the Xuanyin Ning Formula combined with intrapleural injection of bevacizumab via chest tube drainage is effective in treating malignant pleural effusion. It will also evaluate the safety of this combination therapy. The main questions it aims to answer include:

Does the Xuanyin Ning Formula combined with intrapleural injection of bevacizumab via chest tube drainage improve the objective response rate (ORR) of pleural effusion in patients with malignant pleural effusion? Does this combination therapy affect the duration of response (DoR), progression-free survival (PFS), overall survival (OS), degree of dyspnea, quality of life, and Traditional Chinese Medicine (TCM) pattern/syndrome evaluation in patients with malignant pleural effusion?

Participants will:

Receive intrapleural injection of bevacizumab via chest tube drainage, and take either Xuanyin Ning Formula or placebo granules daily for 8 weeks.

Undergo ultrasound assessment of pleural effusion at 2, 4, 8, and 12 weeks after the first intrapleural injection during closed chest drainage, followed by ultrasound assessments every 3 months (±7 days) until pleural effusion progression.

Inclusion Criteria:

• Patients with advanced non-squamous non-small cell lung cancer who have failed at least first-line systemic therapy;

• Presence of unilateral pleural effusion confirmed as malignant by pathology or cytology, with at least moderate volume requiring drainage (moderate pleural effusion defined as: supine ultrasound examination showing pleural effusion ≥3 cm, or sitting ultrasound examination showing pleural effusion ≥4 cm,accompanied by clinical symptoms such as chest tightness and dyspnea);

• Age 18-75 years;

• ECOG performance status 0-2;

• Traditional Chinese Medicine (TCM) syndrome differentiation classified as Xuanyin (suspension fluid) with fluid retention in the chest and hypochondrium;

• Expected survival of at least 3 months;

• Voluntarily signed informed consent before treatment;

• No contraindications to chest tube placement for drainage;

• Adequate major organ function, including:

  1. Complete blood count:

     White blood cell count ≥ 4.0×10⁹/L Absolute neutrophil count ≥ 1.5×10⁹/L Platelet count ≥ 100×10⁹/L Hemoglobin ≥ 90 g/L

  2. Blood biochemistry:

     Total bilirubin ≤ 1.5×ULN ALT ≤ 2.5×ULN, AST ≤ 2.5×ULN Serum creatinine ≤ 1.5×ULN, or creatinine clearance ≥ 50 mL/min (Cockcroft-Gault formula)

  3. Coagulation function:

     International normalized ratio (INR) ≤ 1.5×ULN Activated partial thromboplastin time (APTT) ≤ 1.5×ULN

  4. Blood glucose: within normal range, or diabetic patients under treatment with stable blood glucose control;

• Female subjects of childbearing potential must have a negative serum pregnancy test within 72 hours before starting study drug administration, and must use effective contraception (e.g., intrauterine device, contraceptive pills, or condoms) during the study period and for at least 3 months after the last dose. -Male subjects with a partner of childbearing potential must use effective contraception during the study period and for 3 months after the last dose;

• Good subject compliance, able to follow up for efficacy and adverse events/reactions as required by the protocol.

Exclusion Criteria:

• The location of pleural effusion is unsuitable for drainage, or the patient would not benefit from intrapleural drug administration (e.g., severe loculation/septation);
• Other contraindications to indwelling chest tube placement;
• Pleural effusion with active infection;
• Prior history of ipsilateral chest tube drainage and intrapleural anti-tumor drug therapy or pleurodesis;
• Prior history of empyema or chylothorax;
• Participation in another clinical trial within 4 weeks before signing informed consent;
• Known allergy to any component of the study drugs;
• Severe bleeding tendency or active bleeding;
• Uncontrolled severe hypertension;
• Recent (within 3 months) thromboembolic events, such as deep vein thrombosis, pulmonary embolism, cerebral infarction, etc.;
• Prior severe adverse reactions to intravenous bevacizumab, such as severe proteinuria, gastrointestinal perforation, hypertensive crisis, etc.;
• Severe cardiac, hepatic, or renal insufficiency;
• Pregnant or breastfeeding women;
• Subjects with other active infectious diseases in the acute phase;
• Any other factors that, in the investigator's judgment, may lead to premature termination of the study, such as other serious diseases (including psychiatric disorders) requiring concomitant treatment, alcoholism, drug abuse, family or social factors that may affect the subject's safety or compliance.