Clinical Study Evaluating the Safety and Efficacy of IC19 CAR-T Cell Therapy for Refractory Systemic Lupus Erythematosus

1. The "3+3" dose escalation method will be adopted, with 1 × 10 \^ 8 CAR-T cells/dose and 2 × 10 \^ 8 CAR-T cells/dose, and two dose groups increasing sequentially. Due to the specificity of cell preparations, it is allowed for the actual dosage of each dose group to fluctuate by ± 30%. 2. Three subjects are enrolled in each dose group first, and within the same dose group, the cell transfusion interval between the first two subjects should not be less than 14 days. If no dose limiting toxicity (DLT) is observed in a certain dose group, the dose will be increased to the next dose; If one case of DLT occurs, this dose group needs to be divided into three additional subjects (a total of six subjects). If no new DLT occurs, the dosage will be increased to the next dose; If more than 1/6 of the 6 subjects develop DLT, the dose escalation will be terminated, and the Safety Review Committee (SRC) will discuss whether to reduce the dose and continue the monotherapy study. 3. Definition of DLT: Any of the following events related to the investigational drug (definitely related, likely related, possibly related) that occur within 28 days after a subject receives any IC19 CAR-T cell infusion: 1\) Any grade 4 or 5 adverse events related to IC19 CAR-T cells that occur after treatment, excluding laboratory test indicators of no clinical significance; 2) Any grade 3 adverse events related to IC19 CAR-T cells that occur after treatment and do not improve to ≤ grade 2 within 7 days, excluding clinically insignificant laboratory test indicators; 3) Any grade 3 epileptic seizures that occur after treatment and cannot be relieved to ≤ grade 2 within 3 days; The following expected events will not be considered DLT: Hematology: 1. Grade 3 neutropenia or Grade 4 neutropenia lasting no more than 28 days; 2. Grade 3 or 4 leukopenia; 3. Grade 3 or 4 lymphocyte reduction; 4. Grade 3 anemia or Grade 4 anemia lasting no more than 28 days; 5. Grade 3 thrombocytopenia or Grade 4 thrombocytopenia lasting no more than 28 days; 6. Other types of blood cell reduction besides those mentioned above. Non hematology: 1. Grade 3 transaminase and bilirubin elevation should be restored to ≤ Grade 2 within 2 weeks; 2. Grade 3 hemophagocytic syndrome recovers to ≤ Grade 2 within 2 weeks; 3. Grade 3 chills, recover to ≤ Grade 2 within ≤ 72 hours; 4. Grade 3 hypotension (without other CRS symptoms), requiring vasopressor support and recovering to ≤ Grade 2 within ≤ 72 hours; 5. Level 3 CRS, recover to ≤ Level 2 within ≤ 72 hours; 6. Grade 3 ICANS ≤ 7 days, with remission to ≤ Grade 2 within 1 week and remission to baseline within ≤ 28 days. For grade 3 or 4 toxicity that occurs after 28 days of IC19 CAR-T cell transfusion, SRC will discuss the specific situation. In this study, except for CRS and ICANS, which will be classified according to the ASTCT 2019 consensus grading criteria, adverse events of subjects will be classified according to the National Cancer Institute (NCI) Common Terminology for Adverse Events (CTCAE 5.0).