A Study of SI-B001+SI-B003 Combined With Platinum-based Chemotherapy as First-line Treatment in Patients With Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma

Inclusion Criteria:

1. Sign the informed consent form voluntarily and follow the protocol requirements;

2. Gender is not limited;

3. Age ≥18 years old and ≤75 years old;

4. Expected survival time ≥3 months;

5. Patients with recurrent or metastatic head and neck squamous cell carcinoma;

6. Consent to provide tumor tissue samples or fresh tissue samples archived from theprimary or metastatic lesions within 2 years;

7. At least one measurable lesion meeting the RECIST v1.1 definition was required;

8. Physical status score: ECOG ≤1;

9. The toxicity of previous antineoplastic therapy has returned to ≤ grade 1 as definedby NCI-CTCAE v5.0;

10. No severe cardiac dysfunction, left ventricular ejection fraction ≥50%;

11. No blood transfusion or colony-stimulating factor was allowed within 14 days beforethe first use of the study drug, and the organ function level must meet therequirements;

12. Coagulation function: international normalized ratio (INR) ≤1.5, and activatedpartial thromboplastin time (APTT) ≤1.5×ULN;

13. Urinary protein ≤1+ or ≤1000mg/24h;

14. Fertile female subjects, or male subjects with fertile partners, must use highlyeffective contraception from 7 days before the first dose until 24 weeks after thedose. Female subjects of childbearing potential had to have a negative serumpregnancy test within 7 days before the first dose.

Exclusion Criteria:

1. Squamous cell carcinoma of the nasopharynx, salivary gland, paranasal sinus, skin orof unknown primary site;

2. Patients with any of the following conditions were not eligible for the study: a)suitable and willing for local treatment; b) received systemic therapy, excludingtreatment for locally advanced disease as part of multimodal therapy;

3. Patients with active central nervous system metastasis;

4. Who had participated in any other clinical trial within 4 weeks before the studydose;

5. Received radiotherapy within 4 weeks before the first dose of study drug;

6. Use of traditional Chinese medicine with anti-tumor indications within 2 weeks;

7. Had undergone major surgery within 4 weeks before the first dose;

8. Systemic corticosteroids or immunosuppressive agents were required within 2 weeksbefore study dosing;

9. Pulmonary disease was defined as ≥ grade 3 according to NCI-CTCAE v5.0; Patientswith existing or a history of interstitial lung disease (ILD);

10. Have active infection requiring intravenous anti-infective therapy;

11. Had received immunotherapy and had grade ≥3 irAE or grade ≥2 immune-relatedmyocarditis;

12. Received live attenuated vaccine within 4 weeks before the first dose of study drug;

13. Had taken an immunomodulatory drug within 14 days before the first dose of studydrug;

14. Patients at risk for active autoimmune disease or with a history of autoimmunedisease;

15. Other malignant tumors within 5 years before the first administration;

16. Human immunodeficiency virus antibody positive, active tuberculosis, activehepatitis B virus infection or hepatitis C virus infection;

17. Poorly controlled hypertension;

18. Patients with poor blood glucose control before the first dose;

19. Had a history of severe cardiovascular and cerebrovascular diseases;

20. Previous history of allogeneic stem cell, bone marrow or organ transplantation;

21. Patients with massive or symptomatic effusions or poorly controlled effusions;

22. Patients with a history of allergy to recombinant humanized antibodies or to any ofthe excipients of SI-B001 or SI-B003;

23. Had severe infusion reactions to antibody therapy in the past;

24. Had autologous or allogeneic stem cell transplantation;

25. Pregnant or lactating women;

26. The investigator did not consider it appropriate to apply other criteria forparticipation in the trial.