XKDCT-023

This study is a phase I multicenter, single arm, open, dose increasing, single treatment clinical study. This study plans to recruit a total of about 10-16 adult patients with CD19 positive recurrent or refractory DLBCL for a single autologous car-t cell therapy. There are three dose groups in the study. The first dose group has one patient. If there is no dose limiting toxicity (DLT), it can be increased to the second dose group, otherwise it will continue to be enrolled according to the "3 + 3" method; The follow-up dose group is conducted according to the traditional "3 + 3" design, that is, three subjects are first enrolled in a dose group. If there is no dose limiting toxicity (DLT) in the three patients in the dose group, it can be increased to the next higher dose after completing the DLT observation period; If DLT occurs in 1 of the 3 patients in the dose group, it is necessary to continue to enroll 3 patients in the dose group for DLT observation. The highest dose level of DLT in less than or equal to 1 of the last 6 confirmed patients will be defined as MTD. The safety of car-t treatment was evaluated by observing the adverse events after cell therapy; Evaluate the effectiveness of car-t treatment compared with the results or historical data of the patient's own previous standard treatment regimen. Blood and bone marrow were collected before and 12 months after cell infusion, the number and activity of car-t cells were detected, and the pharmacokinetics (PK) of car-t cells was evaluated.