Becotatug Vedotin for LA-NPC With a Suboptimal Response to Induction Chemotherapy Combined With Immunotherapy

Inclusion Criteria: * Voluntary participation and written informed consent must be signed. * Age between 18 and 70 years, male or non-pregnant female. * Pathologically confirmed nasopharyngeal non-keratinizing carcinoma (differentiated or undifferentiated type, i.e., WHO type II or type III). * Stage Any T N2-3 or T4N1 (AJCC 9th edition), with no distant metastasis, and previously untreated nasopharyngeal carcinoma. * Efficacy after 3 cycles of induction immunochemotherapy assessed as stable disease (SD) or progressive disease (PD) by nasopharyngoscopy and contrast-enhanced MRI of the nasopharynx and neck. * ECOG performance status score of 0 or 1. * Adequate hematological function: Hemoglobin (HGB)≥90g/L, White Blood Cell (WBC) ≥ 4.010\^9/L, and Platele (PLT) ≥10010\^9/L. * Adequate hepatic function: ALT and AST≤2.5Upper Limit of Normal (ULN), total bilirubin ≤2.0ULN, and serum albumin≥30g/L. * Adequate renal function: Serum creatinine ≤ 1.5\*ULN or calculated creatinine clearance (CrCl) ≥ 60 mL/min (using the Cockcroft-Gault formula). * International Normalized Ratio (INR) and Activated Partial Thromboplastin Time (APTT) ≤ 1.5 \*ULN (unless the subject is receiving anticoagulant therapy and the coagulation parameters (PT/INR and APTT) are within the expected therapeutic range for the anticoagulant at the time of screening). Exclusion Criteria: * Patients with recurrent or distant metastatic nasopharyngeal carcinoma. * Pathological diagnosis of keratinizing squamous cell carcinoma (WHO Type I). * Patients who have previously received radiotherapy or systemic chemotherapy. * Women who are pregnant or breastfeeding, or individuals of childbearing potential who are not using effective contraception. * HIV positive. * History of other malignancies (except for cured basal cell carcinoma or cervical carcinoma in situ). * Patients who have previously received immune checkpoint inhibitors (e.g., CTLA-4, PD-1, PD-L1 inhibitors).