Can a One-Two punch of radiation and immunotherapy shrink head and neck tumors before surgery?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Pathologically confirmed, initially treated, surgically resectable head and neck squamous cell carcinoma. * Clinical stage III to IVB (AJCC 8th edition), except HPV-positive oropharyngeal cancer * Following multidisciplinary discussions involving otolaryngologists and radiation oncologists, the assessment concluded that the tumor is resectable or marginally resectable and suitable for preoperative SBRT * Karnofsky Performance Status score ≥ 70 * Ages 18 to 70 * The primary organ functions meet the test requirements * Patients participate voluntarily and sign informed consent forms Exclusion Criteria: * Patients previously treated with head and neck surgery were excluded from diagnostic biopsies of primary and regional lymph nodes * Previous chemotherapy for any reason, or radiotherapy in the head and neck area, or molecular targeted drug therapy; Previously received anti-PD-1, anti-PD-L1, anti-PD-L2 and other drugs or drugs acting on another irritating or co-inhibitory T cell receptor (such as CTLA-4, OX 40, CD137) treatment, or cell biotherapy * Pregnant or lactating women * Have had or co-had other malignancies * The patient also has a serious, uncontrolled illness * Heart, brain, lung and other important organ function abnormal. Patients with hypertension (systolic blood pressure \>140 mmHg, diastolic blood pressure \>90 mmHg) who cannot be reduced to the normal range by antihypertensive drugs have grade I or above myocardial ischemia or myocardial infarction, arrhythmia, and grade II cardiac insufficiency; Abnormal coagulation function (INR \>1.5 or prothrombin time (PT) \> ULN+4 seconds or APTT \>1.5 ULN), have a tendency to bleed or are receiving thrombolytic or anticoagulant therapy; Have a definite bleeding tendency; Patients with positive urinary protein (urinary protein test 2+ or more, or 24-hour urinary protein quantification \>1.0g) * Glucocorticoid therapy for 30 days prior to initial administration (prednisone equivalent dose \> 10mg daily); Have an active autoimmune disease that has required systemic treatment (i.e., disease-modulating drugs, corticosteroids, or immunosuppressive drugs) in the last 2 years * History of non-infectious pneumonia requiring corticosteroid treatment within 1 year prior to the first dose administration or current presence of interstitial lung disease * Active infections such as tuberculosis that require systemic treatment * A known history of human immunodeficiency virus (HIV) infection (i.e. HIV 1/2 antibody positive) * Untreated active hepatitis B; Note: Hepatitis B subjects who met the following criteria were also eligible for inclusion: HBV viral load must be \<1000 copies /ml (200 IU/ml) prior to initial dosing, and subjects should receive anti-HBV therapy to avoid viral reactivation throughout study chemotherapeutic therapy. Subjects with anti-HBC (+), HBsAg (-), anti-HBS (-) and HBV viral load (-) do not need to receive prophylactic anti-HBV therapy, but need to closely monitor viral reactivation. Active HCV-infected subjects (HCV antibody positive and HCV-RNA levels above the lower limit of detection) * Patients who have a history of psychotropic substance abuse and cannot abstain or have mental disorders * The investigator determines other circumstances that may affect the conduct of the clinical study and the determination of the study results * While participating in another therapeutic clinical study