CD19 and B-cell non-Hodgkin lymphoma: When the programmed cell death protein 1 (PD-1)-blocking antibody pembrolizumab was administered to 12 patients with refractory B-cell NHL who experienced progression after anti-CD19 CAR T-cell therapy, it induced a CAR T-cell re-expansion peak in 75% of treated patients, and an antitumor response in 27% of them (136).