This study is designed as a phase III, randomized, double-blind, placebo-controlled study.~After the stratification procedure, subjects are randomized in a 1:1 ratio into 2 groups:~BCD-217 + placebo (4 doses) → prolgolimab (BCD-217 group)~Prolgolimab + placebo (4 doses) → prolgolimab (BCD-100 monotherapy group)
The aim of study is to investigate the efficacy, safety, immunogenicity, pharmacokinetics, and pharmacodynamics of BCD-217 followed by prolgolimab monotherapy versus prolgolimab monotherapy as first-line therapy in subjects with unresectable or metastatic melanoma.