After anti-PD-1 treatment, circulating T cells were activated in responders, and no significant expansion of CART19/20 cells was detected. Our data suggest that PD-1 blockade therapy can be active in patients with relapsed/refractory DLBCL after failure of CAR T cell therapy who had PD-L1 expression in tumor cells and high PD-1 level in tumor-infiltrated T cells.