Inclusion Criteria:
1. Age 18-75 years
2. Pathologically confirmed primary head and neck squamous cell carcinoma (excluding nasopharyngeal carcinoma)
3. Clinical stage II (8th edition TNM staging), no distant metastasis, primary tumor resectable
4. ECOG sccore 0-1
5. No prior radiotherapy, chemotherapy, immunotherapy, or biological therapy for the current head and neck tumor
6. Willing to undergo surgical treatment
7. No significant contraindications to immunotherapy, radiotherapy, or chemotherapy
8. Major organ function meets the following criteria: a) Hematologic: WBC ≥ 4.0 × 10⁹/L, ANC ≥ 1.5 × 10⁹/L, PLT ≥ 100 × 10⁹/L, Hb ≥ 90 g/L (no blood transfusion or blood products, no G-CSF or other hematopoietic growth factors within 14 days); b) Biochemistry: serum albumin ≥ 3.0 g/dL (30 g/L), TBIL ≤ 1.5 × ULN, ALT and AST ≤ 2.5 × ULN, BUN and CRE ≤ 1.5 × ULN or endogenous creatinine clearance ≥ 60 mL/min (Cockcroft-Gault formula); c) Adequate coagulation: defined as INR or PT ≤ 1.5 × ULN; if the subject is receiving anticoagulation therapy, PT within the intended therapeutic range of the anticoagulant is acceptable
9. Both male and female subjects are eligible; women of childbearing potential must have a negative pregnancy test (serum or urine) within 7 days prior to enrollment and must agree to use effective contraception during the study and for 2 months after the last dose of anti-PD-1 antibody. Male subjects with female partners of childbearing potential must agree to use effective contraception during the study and for 2 months after the last dose of anti-PD-1 antibody
10. The subject voluntarily enrolls in this study, signs the informed consent form, demonstrates good compliance, and cooperates with follow-up
Exclusion Criteria:
1. Prior treatment with anti-PD-1/PD-L1 antibodies, anti-PD-L2 antibodies, anti-CD137 antibodies, CTLA-4 antibodies, or other drugs/antibodies targeting T-cell co-stimulation or checkpoint pathways
2. Active severe autoimmune disease. Subjects in stable condition not requiring systemic immunosuppressive therapy are eligible, such as type 1 diabetes mellitus, hypothyroidism requiring only hormone replacement therapy, and skin conditions not requiring systemic treatment (e.g., vitiligo, psoriasis, alopecia)
3. Congenital or acquired immunodeficiency (e.g., HIV infection), active hepatitis B (HBV-DNA ≥ 10⁴ copies/mL), or hepatitis C (HCV antibody positive and HCV-RNA above the lower limit of detection)
4. Known hypersensitivity to the study drug or any of its excipients, or history of severe allergic reaction to other monoclonal antibodies
5. Within 6 months prior to randomization: myocardial infarction, severe/unstable angina, NYHA class ≥ 2 cardiac dysfunction, clinically significant supraventricular or ventricular arrhythmias, or symptomatic congestive heart failure
6. Receipt of a live vaccine within 4 weeks prior to the first dose of study drug; inactivated influenza vaccine administered by injection is permitted, while intranasal live attenuated influenza vaccine is not permitted
7. Known history of allogeneic organ transplantation or allogeneic hematopoietic stem cell transplantation
8. Known history of psychotropic substance abuse or drug addiction
9. Pregnant or lactating women
10. Diagnosis of any other malignancy within 5 years prior to study entry, except for curatively treated localized cancers including basal cell carcinoma or squamous cell carcinoma of the skin, superficial bladder cancer, cervical carcinoma in situ, ductal carcinoma in situ of the breast, and papillary thyroid carcinoma
11. Any other severe physical or psychiatric illness or laboratory abnormality that may increase the risk of study participation, interfere with study results, or render the patient unsuitable for study participation in the opinion of the investigator
