Paclitaxel Polymersomes + Carboplatin + Adebelimab: Neoadjuvant Phase Ⅱ Single-Arm Study for Resectable Mucosal Melanoma

Inclusion Criteria:

1. Age ≥ 18 years old.
2. Histopathologically confirmed resectable mucosal melanoma.
3. Subjects must provide 5 formalin-fixed paraffin-embedded (FFPE) tissue sections collected before treatment, or be willing to undergo needle biopsy for pathological tissue acquisition to facilitate pathological assessment.
4. ECOG (Performance Status, PS) score of 0-1.
5. No prior treatment with immune checkpoint inhibitors such as anti-CTLA-4, anti-PD-1, or anti-PD-L1 monoclonal antibodies.
6. No prior treatment with taxane-based drugs.
7. Presence of measurable lesions (per RECIST 1.1 criteria).
8. No history of immunosuppressant use within 6 months prior to enrollment.
9. Hematological and biochemical test results meeting the following criteria:

   i. Neutrophil count ≥ 1,500 × 10⁹/L; ii. Platelet count ≥ 100 × 10⁹/L; iii. Hemoglobin \> 9.0 g/dL; iv. Serum creatinine ≤ 1.5 × upper limit of normal (ULN) or creatinine clearance (CrCl) ≥ 40 mL/min; v. Aspartate aminotransferase (AST)/Alanine aminotransferase (ALT) ≤ 3 × ULN; vi. Total bilirubin ≤ 1.5 × ULN.
10. Women of childbearing potential must have a negative serum or urine pregnancy test and agree to use an appropriate contraceptive method (barrier contraception or oral contraceptives).

Exclusion Criteria:

1. Presence of distant metastatic lesions.
2. Active autoimmune disease. Note: Patients with vitiligo, type 1 diabetes mellitus, or Hashimoto's thyroiditis with hypothyroidism who only require hormone replacement therapy may be enrolled if there is no evidence of significant disease recurrence.
3. Need for systemic corticosteroid therapy (\> 10 mg prednisolone \[or equivalent\]/daily) or other immunosuppressant use within 14 days after enrollment. Note: Inhaled or topical corticosteroids, or adrenal hormone replacement therapy (\> 10 mg prednisolone \[or equivalent\]/daily) are acceptable for patients without obvious autoimmune diseases.
4. Concurrent diagnosis of other malignant tumors requiring anti-tumor treatment. Note: Patients may be considered for enrollment if the other malignant tumor has achieved complete remission for 2 years or more and no additional anti-tumor treatment is required during the study period.
5. Patients who are medically, psychologically, or physically unable to complete the study or understand the information provided in the patient brochure, as assessed by the investigator.
6. Prior treatment with anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CTLA-4, or other drugs targeting T-cell costimulatory or immune regulatory pathways.
7. Prior chemotherapy with taxane-based drugs.
8. Positive HIV test result or confirmed diagnosis of acquired immunodeficiency syndrome (AIDS).
9. Known hypersensitivity to the study drugs.
10. Pregnant or lactating women.