Pembrolizumab (MK-3475) Plus Gemcitabine/Cisplatin Versus Placebo Plus Gemcitabine/Cisplatin for First-Line Advanced and/or Unresectable Biliary Tract Carcinoma (BTC) (MK-3475-966/KEYNOTE-966)-China Extension Study

Beijing Cancer Hospital ( Site 0138), Beijing

Peking Union Medical College Hospital ( Site 0150), Beijing

The First Hospital of Jilin University ( Site 0131), Changchun

Zhongshan Hospital Fudan University ( Site 0129), Shanghai

Renji Hospital Shanghai Jiaotong University School of Medicine ( Site 0158), Shanghai

Fudan University Shanghai Cancer Center ( Site 0160), Shanghai

The 81st Hospital of PLA ( Site 0128), Nanjing

Anhui Provincial Hospital ( Site 0140), Hefei

Tianjin Medical University Cancer Institute & Hospital ( Site 0155), Tianjin

The First Affiliated Hospital Zhejiang University ( Site 0136), Hangzhou

Zhejiang Cancer Hospital ( Site 0134), Hangzhou

Fujian Provincial Cancer Hospital ( Site 0154), Fuzhou

900 Hospital of the Joint ( Site 0137), Fuzhou

First Affiliated Hospital of The Third Military Medical University ( Site 0130), Chongqing

Hunan Provincial People Hospital ( Site 0142), Changsha

Hunan Cancer Hospital ( Site 0132), Changsha

The Third Xiangya Hospital of Central South University ( Site 0157), Changsha

Guangdong Provincial People s Hospital ( Site 0161), Guangzhou

Harbin Medical University Cancer Hospital ( Site 0133), Harbin

West China Hospital of Sichuan University ( Site 0147), Chengdu

Tangdu Hospital ( Site 0146), Xi’an

The First Affiliated Hospital of Xi an Jiaotong University ( Site 0145), Xi’an