This is a single-arm, phase Ib study involving HNSCC patients who had received first-line treatment with either PD-1 combined with platinum-based drugs or PD-1 monotherapy. The aim of the study is to evaluate the safety and efficacy of Finotonlimab in combination with Stapokibart in the treatment of recurrent/metastatic HNSCC patients.

This study includes a total of 10 participants. Firstly, five participants will be enrolled to receive the combination therapy regimen. Safety observations will be conducted within 30 days after the third participant completes the third cycle of Stapokibart and Finotonlimab combination therapy. Based on the collected trial data, the investigators will evaluate and provide a safety report. If a major safety event or other factor affecting participant safety was identified, the treatment regimen will be re-evaluated before proceeding with further enrollment. Adjustments to administration frequency, dosage, and sample size can be made, or the trial can be terminated; If no safety concerns are identified, the remaining five participants will be enrolled according to the study protocol.

Inclusion Criteria:

1. Voluntarily sign the ICF;

2. Recurrent/metastatic HNSCC of the oral cavity, oropharyngeal, pharyngeal, and laryngeal regions;

3. Male/female, ≥ 18 years old, ECOG 0~1;

4. After PD-1 and platinum therapy, or PD-1 monotherapy, disease progression occurs within 24 weeks after the last ICI administration (as assessed by RECIST 1.1);

5. Target lesion (RECIST 1.1);

6. Previous PD-L1 expression test results may provide tissue for PD-L1 immunohistochemical testing;

7. Expected to survive for more than 3 months;

8. The main organ functions must meet the following requirements (laboratory test values within 7 days before enrollment must meet the following standards):

   • Blood routine examination: (No blood transfusion, no use of granulocyte colony-stimulating factor, no medication correction within 14 days before screening): a) Neutrophils ≥ 1.5 × 10^9/L; b) Platelets ≥ 75 × 10^9/L; c) Hemoglobin ≥ 90g/L; ② Biochemical examination: (No albumin transfusion within 14 days before screening): a) Blood creatinine ≤ 1.5 x upper limit of normal (ULN), or creatinine clearance rate>50 mL/min; b) Serum total bilirubin ≤ 1.5 × ULN; c) Aspartate transaminase (AST) and alanine aminotransferase (ALT) ≤ 2.5 × ULN; ③ Coagulation function: a) International normalized ratio (INR) ≤ 2.3 or prothrombin time (PT) exceeding the normal control range ≤ 6 seconds.

Exclusion Criteria:

1. Suitable for local treatment;

2. Merge with other malignant tumors;

3. Brain metastasis;

4. If the toxicity does not recover to level 0-1 after surgery/radiotherapy/drug treatment, excluding chronic toxicity;

5. Allergic to known medication ingredients;

6. Major surgeries, radiation therapy (excluding palliative care), chemotherapy, immunotherapy, and biologics within 4 weeks prior to enrollment;

7. Received TKI, palliative surgery, and non-specific immunomodulatory therapy (such as thymosin and interferon) within 2 weeks before enrollment;

8. Use immunosuppressive drugs within 4 weeks before enrollment (excluding short-term, local, and physiological dose hormone therapy);

9. Patients with the following infection conditions:

   Active infections require systemic use of antibiotics; Active mycobacterium tuberculosis infection (i.e. tuberculosis infection); Hepatitis C virus antibody (HCV Ab) positive and hepatitis C virus ribonucleic acid (HCV-RNA) positive; Hepatitis B virus deoxyribonucleic acid (HBV-DNA) ≥ 1000 IU/mL; History of human immunodeficiency virus (HIV) infection or HIV antibody positivity during screening period.

10. Uncontrollable pleural effusion, abdominal effusion, and pericardial effusion;

11. Previous grade ≥ 3 irAE or grade ≥ 2 myocarditis;

12. Have a serious history of cardiovascular and cerebrovascular diseases, including but not limited to:

    Major cardiovascular and cerebrovascular diseases (such as congestive heart failure, acute myocardial infarction, unstable angina, stroke, transient ischemic attack, deep vein thrombosis or pulmonary embolism, etc.) occurred within 6 months before the first administration; Corrected QT interval (QTcF)>480 msec; Echocardiography (ECHO) indicates that the subject's left ventricular ejection fraction (LVEF) < 50%; New York Heart Association (NYHA) heart function classification ≥ 2; Clinically uncontrollable hypertension (If blood pressure is controlled with or without intervention, subjects can continue to be screened); Other cardiovascular and cerebrovascular diseases that have been evaluated by the researchers as unsuitable for participation in this study;

13. Active autoimmune diseases;

14. There is a significant risk of bleeding;

15. Receive a live vaccine within 4 weeks before enrollment;

16. During pregnancy or lactation, subjects with fertility do not receive contraceptive measures;

17. The presence of mental illness may affect the conduct of clinical trials;

18. History of organ transplantation or stem cell transplantation.