This is a first-in-human, Phase 1, open-label, multicenter, dose-escalation study of CK-301, a fully human monoclonal IgG1 antibody targeting PD-L1. The study will consist of 3 periods: Screening (up to 28 days), Treatment (28-day cycles), and Follow-up (up to 6 months). Following the dose escalation portion of the study, additional evaluable subjects may be included in order to further characterize safety and efficacy at selected doses and/or in specific patient sub-groups.