Participants assigned to a primary course of pembrolizumab can receive up to 24 months of treatment. Participants with Stable Disease (SD) or better will then proceed to Post Treatment Follow-up. All efficacy and safety analyses will be based on the primary pembrolizumab course.
Participants who experience disease progression during the Post Treatment Follow-up will be eligible for a Second Course of pembrolizumab treatment for up to 1 additional year. With Amendment 05, all Second Course participants will be treated with a fixed dose of pembrolizumab 200 mg Q3W. With Amendment 06, after the study has achieved its key objectives or the study has ended, participants will be discontinued from this study and enrolled in an extension study to continue protocol-defined assessments and treatment.