Phase II Study for Combination of Camrelizumab and SBRT in the First-line Treatment for R/M HNSCC

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.