Sintilimab Combined With Chemotherapy and Radiotherapy in Newly Diagnosed Metastatic Nasopharyngeal Carcinoma: A Multicenter Study

Inclusion Criteria: * Pathologically diagnosed nasopharyngeal cancer with distant metastasis; not received anticancer treatment. * ECOG Score (PS score) 0 or 1. * Neutrophil count \> 1.5\*10\^9/L, hemoglobin \> 90g/L, and platelet count \> 100\*10\^9/L. * ALT or AST level \< 2.5 times upper normal limit (upper limit of normal, ULN), bilirubin level \< 1.5 times ULN. * Creatinine clearance level \> 60 ml/min. * Patients must sign an informed consent and must be willing and able to comply with the visit, treatment protocol, laboratory tests and other requirements specified in the study protocol. * Pregnant female subjects must agree to use reliable contraception within 1 year from the screening visit to the last Sintilimab administration. Exclusion Criteria: * Age\> 65 years old or \<18 years old. * HBsAg positive and HBV DNA\> 10\*10\^3 copy number/ml. * HCV antibody positive. * Active, known, or suspected autoimmune diseases. Subjects with type I diabetes, hypothyroidism with only hormone replacement therapy, and skin disease without systemic treatment (such as vitiligo, psoriasis, or alopecia) can be selected. * A history of interstitial lung disease. * Received systemic hormone or other immunosuppressive therapy with an equivalent dose of\> 10mg of prednisone per day within 28 days prior to signing the informed consent. Subjects with a systemic hormone dose of 10mg prednisone per day or inhaled / topical corticosteroids may be enrolled. * Received or will be vaccinated within 30 days before signing the informed consent. * Pregnancy or breastfeeding women (pregnancy tests should be considered). * Other malignancies within 5 years, except carcinoma in situ, fully treated non-melanoma skin cancer, and papillary thyroid carcinoma. * previous allergies to macromolecular protein preparations, or any component of Sintilimab. * Human immunodeficiency virus (HIV) infection. * Other conditions that may affect the safety or trial compliance of the subject, including symptomatic heart failure, unstable angina, myocardial infarction, active infection requiring systemic treatment, mental illness or family and social factors.