In an open-label , international , multicentre expansion cohort of a phase @ trial , patients ( aged @ years ) with advanced melanoma whose disease had progressed after at least two ipilimumab doses were randomly assigned with a computer-generated allocation schedule ( @:@ final ratio ) to intravenous pembrolizumab at @ mg/kg every @ weeks or @ mg/kg every @ weeks until disease progression , intolerable toxicity , or consent withdrawal .