Tislelizumab Combined With Capecitabine for Nasopharyngeal Carcinoma With Residual EBV DNA After Radiotherapy

Inclusion Criteria: 1. Age ≥18 years; 2. Histologically confirmed nasopharyngeal carcinoma; 3. Expected survival time ≥12 weeks; 4. ECOG performance status: 0-1; 5. Received definitive radiotherapy (± induction and/or concurrent chemotherapy); 6. Plasma EBV DNA \>0 copies/mL within the period from 1 week before to 4 weeks after completion of radiotherapy ; 7. Adequate organ function meeting the following criteria: Hematological: a. Hemoglobin (HB) ≥90 g/L; b. Absolute neutrophil count (ANC) ≥1.0×10⁹/L; c. Platelet count (PLT) ≥80×10⁹/L; Biochemical: a. Total bilirubin (BIL) \<1.5× upper limit of normal (ULN); b. ALT and AST \<2.5×ULN; c. Serum creatinine (Cr) ≤ULN, and creatinine clearance rate ≥50 mL/min (calculated by Cockcroft-Gault formula); d. Normal myocardial enzymes and thyroid function; e. Normal cardiac function assessed by echocardiography. 8. Signed informed consent with willingness to comply with the study protocol. Exclusion Criteria: 1. Histologically confirmed keratinizing squamous cell carcinoma (WHO I)； 2. Distant metastasis detected by pre-treatment clinical or imaging examinations; 3. History of allergy to any component of monoclonal antibodies, tislelizumab, or capecitabine; 4. History of autoimmune diseases, except for the following conditions (eligible after evaluation): 1. Autoimmune-related hypothyroidism on stable thyroid hormone replacement therapy; 2. Type I diabetes mellitus under stable insulin therapy with controlled blood glucose; 5. Previous or concurrent malignancies (except those cured and disease-free for \>5 years, e.g., basal cell carcinoma, cervical carcinoma in situ); 6. Positive pregnancy test in women of childbearing potential; 7. Concurrent medical conditions that may compromise patient enrollment or safety during the study; 8. History of idiopathic pulmonary fibrosis, drug-induced pneumonitis, organizing pneumonia, idiopathic pneumonia, or other active pulmonary diseases; 9. Active psychiatric disorders or other mental conditions affecting informed consent comprehension; 10. Uncontrolled active infections, including tuberculosis, hepatitis B (HBsAg+), hepatitis C, or HIV (HIV antibody+); 11. Significant cardiovascular diseases: NYHA Class II or higher, myocardial infarction within 1 year, unstable angina, or supraventricular/ventricular arrhythmias requiring clinical intervention; 12. Factors affecting drug administration, distribution, metabolism, or excretion (e.g., psychiatric/neurological disorders, chronic diarrhea, ascites, pleural effusion); 13. Unwillingness to sign informed consent.