Clinical Study of CD19 Targeted Universal Chimeric Antigen Receptor T Lymphocytes (UCAR-T) for the Treatment of Refractory Juvenile Dermatomyositis (RJDM)

Inclusion Criteria:

• (1) Age ≥ 5 years old;

• (2) Diagnosis of juvenile dermatomyositis (JDM) according to Bohan and Petercriteria;

• (3) Meeting the classification criteria for RJDM, and meeting condition ① and anyone of ② to ⑤ conditions:

• Intolerance or inadequate response to glucocorticoids (prednisone 1-2mg/kg/d orequivalent dose of other hormones) and at least two immunosuppressants, withhormone therapy lasting for at least 6 months;

• Rapid progression of the disease and/or involvement of organs such aslungs, heart, and gastrointestinal tract;

• Calcification of subcutaneous or muscular and articular tissues;

• Repeated skin rashes or ulcers;

• Repeated or persistent muscle weakness (muscle magneticresonance imaging indicating widespread, diffuse edema or aChildren's Myositis Assessment Scale (CMAS) score < 48, andat least two abnormal results among the following five coremeasurement indicators: Physician's Global Assessment (PhGA) ≥ 2cm, Patient's Global Assessment (PtGA) ≥ 2cm,Disease Activity Score (DAS) ≥ 2 points, Child HealthAssessment Questionnaire (C-HAQ) total score ≥ 0.25 points,and muscle enzyme level > 1.5 times the upper limit ofnormal (ULN));

• (4)Patients with immune-mediated necrotizing myopathy who are positive for SRP orHMGCR antibodies meet the criteria for RJDM and can be directly included;

• (5) Basic normal function of important organs:

• Cardiac function: Left ventricular ejection fraction (LVEF) ≥55%, with nosignificant abnormalities observed in the electrocardiogram;

• Renal function: eGFR ≥ 30mL/min/1.73m2;

• Liver function: AST and ALT ≤3.0 ULN, total bilirubin ≤2.0×ULN (excluding those caused by primary diseases);

• Pulmonary function: SpO2 ≥92%;

• (6) Female subjects of childbearing age have a negative result in the urinepregnancy test and agree to take effective contraceptive measures during the trialuntil one year after infusion;

• (7) The patient or their guardian agrees to participate in this clinical trial andsigns an informed consent form, indicating their understanding of the purpose andprocedures of the clinical trial and their willingness to participate in the study.

Exclusion Criteria:

Subjects meeting any of the following criteria will be excluded from this trial:

• (1) Previously received CAR-T cell therapy (except for those whose safety risks havebeen judged as eliminated by the investigator);

• (2) Accompanied by primary immunodeficiency disease or severe secondaryimmunodeficiency disease that has not been corrected;

• (3) Accompanied by severe, active, or uncontrolled infectious diseases, includingbut not limited to active tuberculosis, latent tuberculous infection, active viralhepatitis, etc.;

• (4) Known to have active malignant diseases or confirmed malignancies beforescreening (including hematological malignancies and solid tumors, except forresected and cured cutaneous basal cell carcinoma);

• (5) Suffering from congenital heart disease or having a history of acute myocardialinfarction within 6 months, or severe arrhythmia (including multifocal frequentventricular supraventricular tachycardia, ventricular tachycardia, etc.); orcomplicated with moderate to large pericardial effusion, severe myocarditis, etc.;or unstable vital signs requiring vasopressors to maintain blood pressure;

• (6) Accompanied by other diseases that require long-term use of glucocorticoids orimmunosuppressants;

• (7) Received solid organ transplantation or hematopoietic stem cell transplantationwithin 3 months before screening; or presence of acute graft-versus-host disease (GVHD) of grade 2 or above within 2 weeks before screening;

• (8) Positive for hepatitis B surface antigen (HBsAg) or hepatitis B core antibody (HBcAb) and peripheral blood hepatitis B virus (HBV) DNA titer detection is greaterthan the normal reference range; or positive for hepatitis C virus (HCV) antibodyand peripheral blood hepatitis C virus (HCV) RNA titer detection is greater than thenormal reference range; or positive for human immunodeficiency virus (HIV) antibody;or positive for syphilis test;

• (9) Received live vaccines within 4 weeks before screening;

• (10) Positive blood pregnancy test;

• (11) Participated in other clinical trials within 3 months before enrollment;

• (12) Other conditions that the investigator considers unsuitable for participationin the study.