(UroToday.com) Despite similar mechanisms of action, antibodies (such as nivolumab and pembrolizumab) against the T-cell checkpoint PD-1 protein have different safety and efficacy profiles when used in cancer therapy. This is likely due to in part to differences in antibody humanization, sequence differences in complementarity-determining regions, as well as different pharmacokinetics.1 While durable responses are observed in a subset of patients treated with these agents, further improvements in disease control in the context of immune checkpoint blockade are needed. It has been hypothesized that blocking both T-cell PD-1 as well as its ligands on tumor cells (PD-L1, PD-L2) could have synergistic antitumor effects. In this presentation, Dr. Juan Martin-Liberal shared data from the phase 2B dose expansion cohort of a clinical trial (NCT03379259) of the anti-PD-L1 antibody BGB-A333 in combination with the anti-PD-1 antibody tislelizumab in patients with advanced urothelial carcinoma who progressed after platinum therapy.