Autologous CD19CAR-T Therapy for Recurrent/Refractory Autoimmune Diseases

This study is a single center, open label exploratory clinical trial aimed at evaluating the safety and efficacy of autologous CD19 CAR-T therapy in subjects with autoimmune diseases.

The study will adopt the traditional dose escalation model "3+3" design, with three dose groups set up, starting at a dose of 0.5 × 106 CAR+T cells/kg, to observe DLT, and conduct a 24 month safety and efficacy follow-up after cell infusion to observe the safety of autologous CD19 CAR-T and conduct preliminary efficacy evaluation.

Three dose groups were set up, with dose group 1 as the starting dose, following the traditional 3+3 design rule for a single intravenous infusion:

Dose group dosage unit (CAR+T cells/kg) Acceptable dose range Expected sample size (± 30%, CAR+T cells/kg)

1. 0.5 × 106 0.4 × 106\~0.6 × 106 3-6 cases 2. 1.0 × 106 0.7 × 106\~1.3 × 106 3-6 cases 3. 2.0 × 106 1.4 × 106\~2.6 × 106 3-6 cases Dose escalation rule The enrollment starts from dose group 1, and if no DLT occurs in the 3 subjects included, they will be transferred to the next dose group. If one of the three subjects in a certain dose group develops DLT, three additional subjects will be added to the group for cell infusion at the same dose. If there is ≥ 1 case of DLT in the 3 additional cases, it will be reduced to the previous dose group. If there are only 3 subjects in the previous dose group at this time, an additional 3 subjects need to be added for the trial; If there are already 6 subjects in the previous dose group, the trial ends and this dose is the maximum tolerated dose (MTD).

Dose escalation is not allowed for the same subject. For safety reasons, the last subject in the previous dose group was observed for at least 28 days after autologous CD19 CAR-T infusion without DLT. The Safety Review Committee (SRC) held a meeting to decide whether to increase to the next dose group.

During the dose escalation phase, SRC determines whether to continue increasing the dose or explore more subjects in a previously explored dose group based on the safety, efficacy, and pharmacokinetic (PK) results obtained for each dose group, and determines the recommended dose (RD) for subsequent studies.