A and B, Data cutoff date: October 4, 2018. C and D, Data cutoff date: June 17, 2017. Progression-free survival was determined by blinded independent central review according to Response Evaluation in Solid Tumors (RECIST) version 1.1.26 bTMB indicates blood tumor mutational burden; HR, hazard ratio; mut/Mb, mutations per megabase; NR, not reached; OS, overall survival; PFS, progression-free survival.