Camrelizumab After Completion of Radiotherapy for Oligometastatic Nasopharyngeal Carcinoma

Inclusion Criteria:

• Patients with histologically confirmed non-keratinizing (according to World HealthOrganization (WHO) histologically type).
• Patients with oligometastatic NPC (defined as ≤5 metastases, ≤2 organs), without localrecurrence of nasopharynx.
• Completion of radiotherapy 4-12 weeks prior to enrollment. At list one cycle ofadjuvant platinum-based chemotherapy.
• Satisfactory performance status: Karnofsky scale (KPS) > 70.
• Adequate marrow: leucocyte count ≥4000/μL, hemoglobin ≥90g/L and platelet count ≥100000/μL.
• Normal liver function test: Alanine Aminotransferase (ALT)、Aspartate Aminotransferase (AST) <1.5×upper limit of normal (ULN) concomitant with alkaline phosphatase (ALP) ≤2.5×ULN, and bilirubin ≤ULN.
• Adequate renal function: creatinine clearance ≥50 ml/min.
• Expected lifetime over 3 months
• Patients must be informed of the investigational nature of this study and give writteninformed consent.

Exclusion Criteria:

• Previous history of autoimmune disease or unstable autoimmune disease.
• Prior malignancy except adequately treated basal cell or squamous cell skin cancer, insitu cervical cancer.
• Prior therapy with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or anti-CytotoxicT-lymphocyte-associated antigen-4 (CTLA-4) antibody (including ipilimumab or any otherantibody or drug specifically targeting T-cell co-stimulation or checkpoint pathways).
• Active autoimmune disease requiring systemic treatment within the past 3 months or adocumented history of clinically severe autoimmune disease, or a syndrome thatrequires systemic steroids or immunosuppressive agents. Subjects with vitiligo orresolved childhood asthma/atopy are an exception to this rule. Subjects that requireintermittent use of bronchodilators or local steroid injections are not excluded fromthe study. Subjects with hypothyroidism stable on hormone replacement or Sjorgen'ssyndrome are not excluded from the study.
• Any severe intercurrent disease, which may bring unacceptable risk or affect thecompliance of the trial, for example, unstable cardiac disease requiring treatment,renal disease, chronic hepatitis, diabetes with poor control (fasting plasma glucose >1.5×ULN), and emotional disturbance.