Safety and Efficacy of PRG-1801 in Recurrent/Refractory Immune Thrombocytopenia (ITP)

Inclusion Criteria:

1. Age ≥18 years, regardless of gender.

2. Clinically diagnosed with primary immune thrombocytopenia for at least 6months, with a platelet count <30×10^9/L within 48 hours before participatingin the study.

3. Positive for anti-platelet glycoprotein autoantibodies (such as GPIIb/IIIa).

4. Previously received first-line and/or second-line ITP treatment (first-linetreatment includes: corticosteroids or immunoglobulins; second-line treatmentincludes thrombopoietin receptor agonists (such as eltrombopag, romiplostim)and/or rituximab, etc.), but the treatment was ineffective (platelet count <30×10^9/L after treatment, or platelet count did not increase to twice thebaseline value, or there was bleeding), or relapsed after effective treatment (platelet count dropped below 30×10^9/L after effective treatment, or droppedto less than twice the baseline value, or bleeding symptoms occurred) ordifficult to maintain after stopping TPO receptor agonists.

5. Bone marrow examination shows increased or normal megakaryocytes.

6. Basic normal function of important organs:

• Echocardiography indicates an ejection fraction ≥50%, and the electrocardiogramshows no significant abnormalities.

• Creatinine clearance rate (CrCl) (Cockcroft-Gault formula) ≥30 mL/min.

• Alanine transaminase (ALT) and aspartate transaminase (AST) ≤3.0× the upperlimit of normal (ULN).

• Total bilirubin (TBIL) and alkaline phosphatase (AKP or ALP) ≤2.0×ULN (Gilbert's syndrome ≤ 3.0×ULN).

• Absolute lymphocyte count (ALC) ≥0.5×10^9/L; absolute neutrophil count (ANC) ≥1×10^9/L; hemoglobin (Hb) ≥60 g/L; platelet count ≥10×10^9/L.

• Blood oxygen saturation >92%.

7. Meet the standards for apheresis or venous blood collection, and have nocontraindications to cell collection.

8. Men of reproductive potential and women of childbearing age must agree to useeffective contraception from the signing of the informed consent form until 1year after the use of the study drug. Blood pregnancy tests for women ofchildbearing age must be negative at screening and before cell infusion, andthey must not be breastfeeding.

9. The participant or their guardian agrees to participate in this clinical trialand signs the informed consent form (ICF), indicating their understanding ofthe purpose and procedures of this clinical trial and their willingness toparticipate in the study.

Exclusion Criteria:

1. Thrombocytopenia caused by myelodysplastic syndromes, early aplastic anemia,atypical aplastic anemia, thrombotic thrombocytopenic purpura, etc.

2. Bone marrow examination during the screening period suggests myelofibrosis MF≥2 (European consensus scoring standard Thieleja2005) or bone marrow examinationindicates the presence of primary diseases other than ITP that can causethrombocytopenia.

3. Allergic history to any component in the cell product.

4. Suffering from any of the following heart diseases:

• Congestive heart failure of NYHA class III or IV.

• Myocardial infarction or coronary artery bypass grafting (CABG) or coronarystent implantation within ≤6 months before signing the ICF.

• Clinically significant ventricular arrhythmias, or history of unexplainedsyncope (excluding vasovagal syncope or dehydration).

• Severe non-ischemic cardiomyopathy history.

5. Malignant tumors within the past 3 years before screening, except for thefollowing: malignant tumors that have been treated radically and have no knownactive disease for ≥3 years before enrollment; or well-treated non-melanomaskin cancer with no evidence of disease.

6. Symptomatic deep vein thrombosis or pulmonary embolism within the past 6 monthsor currently requiring anticoagulant therapy.

7. Participation in other interventional clinical studies within 1 month beforescreening.

8. Vaccination with attenuated live vaccines within 4 weeks before screening.

9. Stroke or epileptic seizure within 6 months before signing the ICF (excludingold lacunar cerebral infarction).

10. The following treatments before CAR-T reinfusion: immunosuppressive treatmentwithin 3 days; use of prednisone (or equivalent drugs) at a dose >10mg/daywithin 3 days.

11. The following treatments before CAR-T reinfusion: treatment with B-celldepleting agents such as rituximab within 24 weeks (unless B cells haverecovered); immunoglobulin reinfusion treatment within 4 weeks.

12. Positive for hepatitis B surface antigen (HBsAg) or hepatitis B core antibody (HBcAb) and peripheral blood hepatitis B virus (HBV) DNA titer detectionexceeds the normal range; positive for hepatitis C virus (HCV) antibody andperipheral blood hepatitis C virus (HCV) RNA titer detection exceeds the normalrange; positive for human immunodeficiency virus (HIV) antibody; positivesyphilis test.

13. Other conditions deemed unsuitable for participation in the study by theresearcher.