The goal of this clinical trial is to learn about the efficacy and safety of pablizumab combined with neoadjuvant chemotherapy in patients with locally advanced head and neck squamous cell carcinoma.

The main question it aims to answer is: Pathological complete remission (PCR) rate of tumor after neoadjuvant immunotherapy.

Participants will be asked to perform CT and MRI of head and neck, ultrasonography of cervical lymph nodes and necessary laboratory examinations Before and after neoadjuvant therapy. And will be following-up for at least 1 year.

The secondary questions it aims to answer are:

Objective response rate (ORR) after neoadjuvant therapy

• R0 resection rate
• major pathological remission (MPR) rate
• organ preservation rate
• event-free survival (EFS)
• local recurrence-free survival (LRFS)
• distant metastasis-free survival (DMFS)
• quality of life score (QoL)
• overall survival (OS)
• incidence of adverse events (including neoadjuvant stage AEs and full course AEs) The exploratory question it aims to answer is: clearance of peripheral blood ctDNA.

Inclusion Criteria:

1. age 18-80 years old, including 18 years old and 80 years old;
2. MRI diagnosis of resectable stage III-IVA oropharynx, larynx and hypopharynx squamous-cell carcinoma confirmed by histopathology or cytology;
3. ECOG PS score 0-1;
4. the expression of PD-L1 was detected by immunohistochemistry (TPS and CPS score)
5. having at least one measurable lesion according to RECIST version 1.1;
6. expected survival time ≥6 months;
7. The neutrophil count was ≥1.5 × 10^9/L, the platelet count was ≥100 × 10^9/L, the hemoglobin count was ≥90 g/L
8. renal function was normal: serum creatinine ≤1.5×ULN;
9. the liver function was basically normal: serum total bilirubin ≤1.5 × ULN, serum aspartate transaminase (AST)≤2.5×ULN, serum Alanine transaminase (ALT)≤2.5 ×ULN;
10. female patients had to be negative for a urine pregnancy test before the start of the study (not applicable to patients with bilateral oophorectomy and/or hysterectomy or postmenopausal patients) ;
11. Sign the written informed consent.

Exclusion Criteria:

1. patients were treated with anti-tumor drugs including but not limited to PD-1 inhibitor, CTLA-4 antibody, EGFR monoclonal antibody, EGFR-tki, and anti-angiogenesis drugs;
2. History of autoimmune diseases including but not limited to: myasthenia gravis, myositis, autoimmune hepatitis, systemic lupus erythematosus, Rheumatoid Arthritis, inflammatory bowel disease, Antiphospholipid syndrome vascular thrombosis, Wegener's granulomatosis, Sjögren's syndrome, Guillain-Barré syndrome, multiple sclerosis, vasculitis or glomerulonephritis.
3. participated in other intervention clinical trials within 30 days before screening;
4. history of other malignancies (except cured skin basal-cell carcinoma) ;
5. the presence of serious and poorly controlled co-morbidities (e.g. heart failure, diabetes, hypertension, liver failure, kidney failure, thyroid disease, mental illness, etc.) ;
6. Known to be infected with HIV or active hepatitis or tuberculosis;
7. major surgery or planned surgery within 30 days before the first dose of the trial drug;
8. Persons who are allergic to the use of drugs or their components in the programme;
9. pregnancy (confirmed by blood or urine HCG testing) or lactation in women, or in subjects of reproductive age who were unwilling or unable to use effective contraception (for both male and female subjects) until at least 6 months after the last trial treatment;
10. it is not suitable for the researcher to participate in this study;
11. Unwilling to participate in the study or unable to sign the informed consent.

A otolaryngology patient at Xijing Hospital.