Neoadjuvant Radio-immunotherapy Versus Immunotherapy Alone for Locally Advanced HNSCC

This is a randomized, controlled, open-label, Phase II clinical trial designed to compare the efficacy and safety of neoadjuvant radiotherapy combined with Adebrelimab versus Adebrelimab monotherapy in patients with locally advanced head and neck squamous cell carcinoma (HNSCC). Experimental Arm (Radio-immunotherapy): Patients will receive neoadjuvant radiotherapy (SBRT 24 Gy in 3 fractions) followed by or concurrent with 2 cycles of Adebrelimab (1200mg, Q3W). Control Arm (Immunotherapy alone): Patients will receive 2 cycles of Adebrelimab (1200mg, Q3W) as monotherapy. Following the completion of neoadjuvant therapy, a multidisciplinary team (MDT) will evaluate the patients' response. Eligible patients will then undergo standard surgical resection of the primary tumor and neck dissection within 3 to 4 weeks after the last dose of immunotherapy. The primary endpoint is the Major Pathological Response (MPR) rate, defined as less than or equal to 10% residual viable tumor in the resected specimen. Secondary endpoints include Pathological Complete Response (pCR) rate, Objective Response Rate (ORR) according to RECIST 1.1, Event-Free Survival (EFS), and the incidence of treatment-emergent adverse events (TEAEs) graded by CTCAE 5.0.