Exploratory Clinical Study of Neoadjuvant Immunotherapy Combined With Chemotherapy in Malignant Melanoma of Nasal and Paranasal Mucosa

Inclusion Criteria:

* Histopathologically confirmed diagnosis of malignant melanoma of the nasal cavity and paranasal sinuses.
* T stage of T3 or T4a.
* Age ≥18 years.
* No distant metastasis.
* Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2, with general condition tolerating chemotherapy and general anesthesia for surgery.
* Locally resectable with curative intent, and able to undergo contrast-enhanced CT or contrast-enhanced MRI examinations.
* Adequate organ function: Hematology: white blood cells ≥3.0 × 10\^9/L; absolute neutrophil count ≥1.5 × 10\^9/L; hemoglobin ≥80 g/L; platelets ≥100 × 10\^9/L. Hepatic function: total bilirubin ≤1.5 × upper limit of normal (ULN); AST and ALT ≤3 × ULN. Coagulation: international normalized ratio (INR) or prothrombin time (PT) or activated partial thromboplastin time (aPTT) ≤1.5 × ULN. Renal function: serum creatinine ≤1.5 × ULN.
* Patients with recurrence after prior curative surgery are allowed; for recurrent patients, chemotherapy and immune therapy must have been discontinued for more than 6 months.

Exclusion Criteria:

* Patients who refuse to sign the informed consent form.
* Patients with uncontrolled comorbidities that, in the investigator's judgment, would interfere with treatment.
* Patients currently suffering from another malignant tumor or with synchronous multiple primary tumors that require treatment.
* Patients with surgical contraindications, such as severe cardiopulmonary disease or coagulation disorders.
* Patients with autoimmune diseases.
* Patients currently using immunosuppressants, or receiving systemic glucocorticoids for immunosuppressive purposes (dose \>10 mg/day prednisone or equivalent), and who continue to use them within 2 weeks prior to first dosing.
* Prior treatment with PD-1 monoclonal antibodies or PD-L1 monoclonal antibodies; or a history of severe allergic reactions to other monoclonal antibodies.
* Receipt of a live vaccine within 6 weeks prior to first dosing, or the possibility of receiving a live vaccine during the study.
* Any condition that may compromise protocol adherence or safety during the study.
* Uncontrolled active infection.
* Pregnant or breastfeeding women.
* Any other condition deemed unsuitable for enrollment.