Iparomlimab and Tuvonralimab Combined With SFRT and Definitive Chemoradiotherapy in Locoregionally Advanced Bulky HNSCC

Inclusion Criteria:

1. Age between 18 and 75 years, both sexes eligible;
2. Histologically confirmed head and neck squamous cell carcinoma (HNSCC), diagnosed as locoregionally advanced disease with measurable primary tumor and/or cervical metastatic lymph nodes \>5 cm in maximum diameter, and deemed unresectable by surgical evaluation;
3. Treatment-naive (no prior anti-tumor therapy);
4. At least one measurable lesion (excluding brain metastases) per RECIST 1.1 criteria;
5. ECOG performance status 0-1;
6. Life expectancy ≥12 weeks;
7. Organ function meeting the following criteria (no blood products, colony-stimulating factors, leukocyte/ thrombocyte/ erythrocyte-stimulating agents within 14 days prior to first study drug administration):

   1. Absolute neutrophil count (ANC) ≥1.5×10\^9/L;
   2. Platelets ≥90×10\^9/L;
   3. Hemoglobin ≥8 g/dL;
   4. Serum albumin ≥2.8 g/dL;
   5. Total bilirubin ≤1.5×ULN, ALT/AST/ALP ≤2.5×ULN; if liver metastases present, ALT/AST ≤5×ULN; if liver/bone metastases present, ALP ≤5×ULN;
   6. Serum creatinine ≤1.5×ULN or creatinine clearance \>60 mL/min;
   7. APTT and INR ≤1.5×ULN (patients on stable anticoagulation \[e.g., LMWH, warfarin\] with therapeutic INR acceptable for screening).
8. Voluntary informed consent, good compliance, and willingness to cooperate with follow-up;
9. Investigator determination of potential benefit.

Exclusion Criteria:

1. Those with a history of severe immediate - type allergic reactions to any of the drugs used in this study；
2. Within six months before screening, having any of the following conditions: myocardial infarction, severe/unstable angina pectoris, coronary/peripheral artery bypass grafting, symptomatic congestive heart failure, cerebrovascular accident, transient ischemic attack, or symptomatic pulmonary embolism. Patients known to have coronary artery disease, congestive heart failure that doesn't meet the above criteria, or a left ventricular ejection fraction of less than 50% must have an optimally stable medical regimen as determined by the treating physician. If appropriate, a cardiologist can be consulted；
3. Individuals who have received anti - tumor vaccines or live vaccines within four weeks before the first administration of the study drug；
4. Patients with active autoimmune diseases or a history of autoimmune diseases that are likely to relapse. The following patients are not excluded and can proceed to further screening:

   1. Those with well - controlled type 1 diabetes.
   2. Patients with hypothyroidism that can be controlled with hormone replacement therapy alone.
   3. People with skin diseases that do not require systemic treatment, such as vitiligo, psoriasis, and alopecia.
   4. Any other diseases that are not expected to relapse without external triggers；
5. Those lacking full or restricted civil capacity；
6. Patients with physical or mental disorders who, in the investigator's opinion, are unable to fully or adequately understand the potential complications of this study；
7. Patients with an expected survival time of less than three months；
8. Patients with significantly reduced functions of the heart, liver, lungs, kidneys, and bone marrow；
9. Those with a history of substance abuse or alcohol addiction；
10. Patients whose tumor lesions invade large blood vessels, such as the internal carotid artery and jugular vein and their main branches, with a high risk of bleeding；
11. Subjects who need systemic treatment with corticosteroids (more than 10 mg/day prednisone equivalent) or other immunosuppressants within two weeks before the first use of the study drug, except for the use of corticosteroids for local esophageal inflammation and the prevention of allergies, nausea, and vomiting. In other special cases, communication with the sponsor is required. In the absence of active autoimmune diseases, the inhalation or local use of steroids and adrenal cortical hormone replacement at a dose higher than 10 mg/day prednisone equivalent is allowed；
12. Those with a history of immunodeficiency, including HIV - positive results, other acquired or congenital immunodeficiency diseases, or a history of organ transplantation and allogeneic bone marrow transplantation；
13. Pregnant or lactating female patients, as well as male or female patients who are fertile but unwilling or unable to use contraception throughout the study and for at least one year after the end of the treatment plan；
14. Patients who, in the investigator's opinion, are not suitable for inclusion.