Inclusion Criteria:

- Diagnosed as recurrence/metastatic NPC

- Histopathological diagnosis of NPC(WHO II/III)

- ECOG 0-1 point

- No treatment to r/mNPC, such as radiotherapy, chemotherapy, immunotherapy or
biotherapy;

- No contraindications to immunotherapy and chemoradiotherapy;

- At least one lesion could receive SBRT safely;

- Subject must have a measurable target lesion based on RECIST v1.1;

- Adequate marrow function: WBC count ≥ 3×10E9/L, NE count ≥ 1.5×10E9/ L, HGB ≥ 90g/L,
PLT count ≥ 100×10E9/L;

- Adequate liver function: ALT/AST ≤ 2.5×ULN, TBIL ≤ 2.0×ULN;

- Adequate renal function: BUN/CRE ≤ 1.5×ULN or endogenous creatinine clearance ≥
60ml/min (Cockcroft-Gault formula);

- Take effective contraceptions during and three months after treatment;

- Patients must be informed of the investigational nature of this study and give
written informed consent.

Exclusion Criteria:

- Allergic to monoclonal antibodies, any PD-1 antibody components, gemcitabine and
cisplatin;

- Unexplained fever > 38.5 #, except for tumor fever;

- Have active autoimmune disease (e.g., uveitis, enteritis, hepatitis, hypophysitis,
nephritis, vasculitis, hyperthyroidism, and asthma requiring bronchodilator
therapy);

- Have a known history of human immunodeficiency virus (HIV), active Hepatitis B
(HBV-DNA ≥10E3copiers/ml) or hepatitis C virus (HCV) antibody positive;

- Have New York Heart Association (NYHA) class 3 or 4, unstable angina, myocardial
-infarction within 1 year, or clinically meaningful arrhythmia that requires
treatment; Have known allergy to large molecule protein products or any compound of
study therapy;

- Pregnant or breastfeeding;

- Prior malignancy except adequately treated non-melanoma skin cancer, in situ
cervical cancer, and papillary thyroid carcinoma;

- Have received a live vaccine within 30 days of planned start of study therapy Has
psychiatric drug or substance abuse disorders that would interfere with cooperation
with the requirements of the trial;

- Any other condition, including 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.