Timeline history of approved immune-checkpoint inhibitors to treat melanoma
Level IA evidence includes evidence from meta-analysis of randomized controlled trials.
level IB evidence includes evidence from at least one randomized controlled trial.
Level IIA evidence includes evidence from at least one controlled study without randomization.
Level IIB evidence includes evidence from at least one other type of experimental study.
Level III evidence includes evidence from nonexperimental descriptive studies (i.e. comparative, correlation & case-control).
Level IV evidence includes evidence from expert committee reports or opinions or clinical experience of respected authorities, or both.