Toripalimab Combined With Radiotherapy in the Treatment of Oligometastatic Nasopharyngeal Carcinoma

Inclusion Criteria: 1. Must have signed written informed consent and able to comply with study procedure 2. 18-75 years old 3. Histologically or cytologically confirmed nasopharyngeal carcinoma 4. Pathology or imaging confirmed metastatic nasopharyngeal carcinoma.( Clinical stage of IVB according to the 8th edition of AJCC) 5. Imaging (preferred PET-CT) confirmed oligometastatic NPC (defined as ≤5 metastatic lesions, ≤2 metastatic organs) 6. Have not received any treatment for metastatic nasopharyngeal carcinoma. 7. Unsuitable or unwilling to receive chemotherapy according to the judgment of investigator. 8. Eastern Cooperative Oncology Group (ECOG) Performance Status score 0-1 9. Estimated life ≥ 6 month 10. At least 1 measurable lesions according to RECIST v1.1 11. Adequate organ function, defined as achieving the following laboratory test results within 7 days before enrollment: ANC≥1.5×10\^9/L，PLT≥100×10\^9/L，Hb≥90g/L((Have not accepted blood transfusion or growth factors within 14 days)；the international normalized ratio (INR) or prothrombin time (PT) ≤ 1.5 × ULN; activated partial thromboplastin time(APTT) ≤1.5 × ULN；serum creatinine≤1.5×ULN or estimated glomerular filtration rate(GFR) ≥ 60 mL/min/1.73 m2; total bilirubin≤1.5×ULN（total bilirubin\<3×ULN for patients with Gilbert syndrome）; AST and ALT ≤ 2.5×ULN (AST and ALT ≤ 2.5×ULN for patients with liver metastasis); Exclusion Criteria: 1. Allergy to any component of toripalimab 2. With any active autoimmune disease or a history of autoimmune disease that may relapse Note: Patients with the following diseases were not excluded and should be further screened: Controlled type 1 diabetes; Hypothyroidism (could be controlled just by hormone replacement therapy); Controlled celiac disease; Skin diseases that do not require systemic treatment (e.g. vitiligo, psoriasis, alopecia); Any other disease which is not expected to be relapsed without external stimulate 3. Any active malignancy ≤ 2 years before randomization except for the specific cancer under investigation in this study and any locally relapsed cancer that has been cured after treatment (eg, resected basal or squamous cell skin cancer, superficial bladder cancer, carcinoma in situ of the cervix or breast) 4. Received corticosteroid therapy at a dose ≥ 10 mg prednisone per day or any other systemic immunosuppressive therapy within 14 days prior to enrollment. 5. Patient with uncontrolled diabetes, or abnormal potassium, sodium or corrected calcium levels (≥ grade 1) after receiving standard treatment, or ≥ grade 3 hypoalbuminemia within 14 days prior to enrollment 6. Patient with a history of interstitial lung disease, non-infectious pneumonia or uncontrollable diseases, including pulmonary fibrosis, acute lung disease, hypertension, etc. 7. Evidence of severe chronic or active infections (including tuberculosis infection) requiring systemic antibiotics, antibacterial or antiviral therapy within 14 days prior to enrollment 8. Patient with a history of HIV infection 9. Evidence of contraindications of immunotherapy or radiotherapy 10. Patient with untreated chronic hepatitis B or HBV-DNA≥ 500 IU/mL, or active hepatitis C. Note: Patients with inactive infection of hepatitis B surface antigen (HBsAg), stable hepatitis B after treatment (HBV DNA \< 500 IU/mL）and cured hepatitis C could be included. 11. Have undergone any operation requiring general anesthesia within 28 days prior to enrollment 12. Previous allogeneic stem cell transplantation or organ transplantation 13. Patient with any of the following cardiovascular risk factors: Cardiogenic chest pain within 28 days prior to enrollment, which is defined as moderate pain that limits instrumental activities of daily life; Symptomatic pulmonary embolism within 28 days prior to enrollment; Acute myocardial infarction within 6 months prior to enrollment; Grade III or IV disease according to the New York Heart Association within 6 months prior to enrollment;≥ Grade 2 ventricular arrhythmias within 6 months prior to enrollment or the first administration; With a history of cerebrovascular accident within 6 months prior to enrollment or the first administration 14. Grade 2 peripheral nerve disease according to NCI-CTCAE V5.0 15. Underlying medical conditions (including abnormal laboratory test values) that: affect drug administration; affect the interpretation of toxicity or AE; lead to poor compliance; alcohol or drug abuse or dependence 16. Participate in another interventional clinical study at the same time