This study is a prospective, single-center, open-label, phase II clinical study for patients with recurrent or metastatics quamous cell carcinoma of the head and neck.

Inclusion Criteria:

1. Histologically confirmed squamous cell carcinoma of the head and neck;

2. Patients with untreated recurrent or metastatic disease;

3. Combined positive Score>=1;

4. Aged >=18 years;

5. Eastern Cooperative Oncology Group (ECOG) performance status 0-1;

6. At least one measurable lesion, according to RECIST 1.1;

7. Major organ functions within 28 days prior to treatment meet the following criteria(14 days without transfusion):

   1. HB>=80g/L, ANC>=1.5x10^9/L, PLT >=80x10^9/L;
   2. TBIL<=1.5 ULN, ALT and AST <=2.5 ULN, if there exists hepatic metastases, ALT and AST <=5 ULN, Cr <=1.5 ULN or CCr >=60ml/min;
   3. INR or PT <= 1.5 ULN, APTT <=1.5 ULN (if the patient is receiving anticoagulant therapy, PT and APTT should be within the expected treatment range);
   4. BNP <=ULN;
   5. T3 <=ULN and T4 <=ULN after treatment;

8. Appropriate contraception should be used from the start of treatment to 120 days after the end of treatment; For female subjects with reproductive potential: a negative serum pregnancy test;

9. Have signed consent form.

Exclusion Criteria:

1. Have other malignant tumors in the past 5 years, except for cured in cured basal cell carcinoma, situ cervical carcinoma and thyroid papillary carcinoma ;
2. Known allergic reactions to the components of PD-1 monoclonal antibody;
3. Central nervous system metastasis with symptoms;
4. Treatment with a strong CYP3A4 inhibitor within 1 week or a strong inducer of CYP3A4 within 2 weeks.
5. Congestive heart failure of New York Heart Association (NYHA) Class III or IV;
6. Ischemic cardiovascular events occurred within 1 year prior to the start of treatment;
7. ECG QT interval >500ms;
8. Patients are receiving immunosuppressive therapy;
9. Treatment with an immunotherapy, including anti-PD-1, anti-PD-L1 and anti-CTLA-4;
10. Treatment with an investigational agent within 4 weeks;
11. Treatment with oral or parenteral corticosteroids (>10mg per day) within 2 weeks or a requirement for chronic systemic immunosuppressive therapy;
12. Treatment with anti-tumor vaccine or live vaccines within 4 weeks
13. Surgery or severe trauma within 4 weeks;
14. Active infection;
15. Active autoimmune disease;
16. History of immunodeficiency, including HIV antibody positive, primary immunodeficiency, or the allogeneic organ transplantation and allogeneic hematopoietic stem cell transplantation;
17. History of noninfectious pneumonia;
18. Active tuberculosis within 1 year, or had a history of active tuberculosis infection one year ago but did not receive standard treatment;
19. Active hepatitis, including HBV DNA ≥ 2000IU/ml or 10 ⁴ copies / ml or HCV antibody and HCV-RNA positive;
20. History of alcoholism and drug abuse;
21. Patients with symptoms of gastrointestinal bleeding or risk of bleeding;
22. Patients are pregnant or breast-feeding;
23. Any other condition or circumstance that could interfere with adherence to the study's procedures or requirements, or otherwise compromise the study's objectives.