The aim of this study is to compare the efficacy of Toripalimab Combined with GP Regimen Chemotherapy Versus GP Regimen Chemotherapy for Primary Metastatic NPC.

About 4-10% of patients with nasopharyngeal carcinoma (NPC) have metastatic disease at diagnosis. The treatment recommendation of primary metastatic NPC is systemic chemotherapy. However, the optimal regimen is yet to determine due to lack of prospective randomized trial for this unique group of patients. Generally, GP regimen is used as the first-line treatment of primary metastatic NPC. The aim of this study is to compare the efficacy of Toripalimab Combined with GP Regimen Chemotherapy Versus GP Regimen Chemotherapy for Primary Metastatic NPC.

Inclusion Criteria:

1. Sign an informed consent;
2. Age older than 18 years old and younger than 70 years old;
3. Patients with newly histologically confirmed primary metastatic nasopharyngeal carcinoma;
4. At least one metastatic site that fulfills the criteria of "Evaluable Disease" per RECIST 1.1 Criteria;
5. Anticipated overall survival more than 3 months;
6. Satisfactory performance status: ECOG (Eastern Cooperative Oncology Group) scale 0-1;
7. No primary treatment of radiation, surgery, chemotherapy, targeted therapy and immune therapy post diagnosis of NPC;
8. Neutrophil ≥ 1.5×109 /L and PLT ≥100×109 /L and HGB ≥90 g/L;
9. With normal liver function test (ALT、AST ≤ 3×ULN, TBIL≤ 1.5×ULN, Albumin≥2.8g/dL );
10. With normal renal function test (Creatinine ≤ 1.5 ×ULN and creatinine clearance ≥60 ml/min);
11. HBV DNA<500 IU/mL（or 2500 copies/mL）and HCV RNA negative ;
12. Male and no pregnant female, able to adapt birth control methods during treatment.

Exclusion Criteria:

1. Hypersensitivity to Toripalimab, Gemcitabine, Cisplatin and Capecitabine;
2. Symptomatic spinal cord compression, or high-risk to develop pathological fracture that requires urgent surgery or radiation;
3. Necrotic disease, high-risk of massive nasal bleeding;
4. Suffered from malignant tumors, except cervical carcinoma in situ, papillary thyroid carcinoma, or skin cancer (non- melanoma) within five years;
5. Receive vaccine or live vaccine within 30 days prior to signing the informed consent;
6. Equivalent dose more than prednisone 10mg/d or other immunosuppressive treatments within 28 days prior to signing the informed consent;
7. Severe, uncontrolled medical conditions and infections;
8. Active, known or suspected autoimmune disease; Type I Diabetes, hypothyroidism those only need hormone replacement therapy; vitiligo or inactive asthma who don't need systemic therapy can recruit;
9. History of interstitial lung disease;
10. HIV positive;
11. Hepatitis B surface antigen (HBsAg) positive and HBV-DNA ≥500IU/ml, or 2500cps/ml; Positive HCV RNA;
12. Other diseases which may influence the safety or compliance of the clinical trial, such as heart failure with symptom, unstable angina, myocardial infarction, active infections those need systemic therapy, mental illness, or their family and society factors;
13. Women of child-bearing potential who are pregnant or breastfeeding.