Timing Optimization of Immunotherapy During Neoadjuvant Chemotherapy for Locally Advanced Nasopharyngeal Carcinoma

Inclusion Criteria: * Age between 18 and 70 years Histologically confirmed locoregionally advanced nasopharyngeal carcinoma (AJCC/UICC 8th edition stage II-III) At least one measurable target lesion per RECIST 1.1 ECOG performance status of 0-1 Estimated life expectancy ≥ 6 months Adequate hematologic, hepatic, renal, and coagulation function Negative pregnancy test for women of childbearing potential Willingness to use effective contraception during the study and for 12 months after treatment Signed informed consent Willing and able to comply with study procedures Not participating in any other interventional clinical trials during the study period Exclusion Criteria: * re first dose Active or suspected autoimmune disease requiring systemic treatment Ongoing systemic immunosuppressive therapy Active hepatitis B, hepatitis C, HIV infection, or other serious infections History of another malignancy within 5 years (except non-melanoma skin cancer or in situ cervical cancer) Pregnant or breastfeeding women Inability or unwillingness to use contraception as required Life expectancy \< 6 months