CK-301 is a fully human monoclonal antibody of IgG1 subtype that directly binds to Programmed Death-Ligand 1 (PD-L1) and blocks its interactions with the Programmed Death-1 (PD-1) and B7.1 receptors. The primary objective of this study is to assess the safety, tolerability and preliminary efficacy of CK-301 when administered intravenously as a single agent to subjects with selected recurrent or metastatic cancers.