This study is a randomized, placebo-controlled, double-blind, multicenter phase III clinical study. Target population is patients with recurrent/metastatic nasopharyngeal carcinoma who had not received systemic chemotherapy. Study objective is to compare the efficacy and safety of camrelizumab in combination with gemcitabine and cisplatin with placebo in combination with gemcitabine and cisplatin in study population in China. camrelizumab is a humanized anti-PD1 IgG4 monoclonal antibody.

In this study, eligible subject will be randomized into study arm or control arm to accept study treatment. Treatment cycles of chemotherapy will be at most 6 weeks which will be decided by investigators. Progression-free survival (PFS) determined by the Independent Review Committee (IRC) will be the primary outcome measures.

Inclusion Criteria:

1. Age ≥ 18 years and ≤75 years;
2. Subjects with histopathological diagnosis of nasopharyngeal carcinoma;
3. Primarily metastatic (stage IVB as defined by the International Union against Cancer and American Joint Committee on Cancer staging system for NPC, eighth edition) or recurrent NPC that is not amenable for local regional treatment or curative treatment;
4. Has not received prior systemic treatment;
5. Has a performance status of 0 or 1 on the Eastern Cooperative Oncology Group (ECOG) Performance Status
6. Subject must have a measurable target lesion based on RECIST v1.1;

Exclusion Criteria:

1. Allergic to monoclonal antibodies, any camrelizumab components, gemcitabine, cisplatin and other platinum drugs;

2. Prior therapy as follow:

   • Anti-PD-1 or anti-PD-L1;
   • Received last dose of anticancer therapy (including chemotherapy, radiotherapy, targeted therapy, etc.) within 4 weeks of the first dose of study medication;
   • Concurrent medical condition requiring the use of cortisol (>10mg/day Prednisone or equivalent dose) or other systematic immunosuppressive medications within 14 days before the study treatment. Except: inhalation or topical corticosteroids. Doses > 10 mg/day prednisone or equivalent for replacement therapy;
   • Received major operations or serious injuries within 4 weeks of the first dose of study medication;

3. Not recovered to ≤CTCAE 1 from adverse events (except for hair loss) due to a previously anti-tumor treatment;

4. Pregnancy or breast feeding;