Toripalimab vs. Placebo Wtih GP Induction Chemotherapy in Locoregionally Advanced Nasopharyngeal Carcinoma

Inclusion Criteria:

1. Voluntarily participates and signs an informed consent form.
2. Aged 18-70 years, male or non-pregnant female.
3. Pathologically confirmed nasopharyngeal non-keratinizing carcinoma (differentiated or undifferentiated, i.e., WHO Type II or III).
4. Staging of any T, N2-3 or T4N1 (9th AJCC/UICC staging), with no distant metastasis.
5. ECOG performance status score of 0-1.
6. Hemoglobin (HGB) ≥90 g/L, neutrocyte count≥1.5×10⁹/L, platelets (PLT) ≥100×10⁹ /L.
7. Liver function: Alanine aminotransferase (ALT) and aspartate aminotransferase (AST)≤2.5×upper limit of normal (ULN), and bilirubin ≤ 1.5×ULN.
8. Adequate renal function: creatinine clearance rate ≥ 60 ml/min (Cockcroft-Gault formula).
9. Women of childbearing potential (WOCBP) who are sexually active must be willing to adhere to effective contraception during treatment and for 1 year after the last dose of the study drug. Men who are sexually active with WOCBP must be willing to adhere to effective contraception during treatment and for 1 year after the last dose of the study drug.

Exclusion Criteria:

1. Age \> 70 years or \< 18 years.
2. Patients with recurrence or distant metastases.
3. Pathologically confirmed nasopharyngeal keratinizing squamous cell carcinoma (WHO Type I).
4. Patients who have previously undergone radiotherapy or systemic chemotherapy.
5. Hepatitis B surface antigen (HBsAg) positive and hepatitis B virus DNA \>1000 copies/ml or 200IU/ml.
6. Hepatitis C virus (HCV) antibody positive.
7. Has active autoimmune disease, except type I diabetes, hypothyroidism treated with replacement therapy, and skin disease that doesn't require systemic treatment (e.g., vitiligo, psoriasis, or alopecia).
8. Has any condition that required systemic corticosteroid (equivalent to prednisone \>10mg/d) or other immunosuppressive therapy within 28 days before informed consent. Patients who received systemic corticosteroid equivalent to prednisone ≤10mg/d, inhale or topical corticosteroids will be allowed.
9. Has a known history of active bacillus tuberculosis within 1 year; patients with adequately treated active bacillus tuberculosis over 1 year ago will be allowed.
10. Has a known history of interstitial lung disease.
11. Has received a live vaccine within 30 days before informed consent or will receive a live vaccine in the near future.
12. Is pregnant or breastfeeding.
13. Prior malignancy within 5 years, except in situ cancer, adequately treated non-melanoma skin cancer and papillary thyroid carcinoma.
14. Has known allergy to large molecule protein products or any compound of toripalimab.
15. Has a known history of human immunodeficiency virus infection.
16. Any other condition, including symptomatic heart failure, unstable angina, myocardial infarction, active infection requiring systemic therapy, mental illness, or domestic/social factors, deemed by the investigator to be likely to interfere with a patient's ability to sign informed consent, cooperate and participate in the study or interferes with the interpretation of the results.