This is a phase 1-2, open-label study in subjects with refractory DLBCL, evaluating the safety and efficacy of KTE-C19, an autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy, in combination with atezolizumab, a humanized, monoclonal antibody that binds to PD-L1 and blocks interaction with the PD-1 and B7.1 receptors. The trial will be separated into two distinct phases designated as phase 1 and phase 2.