Study of PN20 in Adult Patients with Primary Immune Thrombocytopenia (ITP)

Key Inclusion Criteria:

1. Aged between 18 and 65 years (inclusive), male or female;

2. Diagnosed with primary immune thrombocytopenia (ITP) and have a disease course ofmore than 6 months;

3. Patients who have no response or relapsed after splenectomy. Or patients who havenot been splenectomised and have completed at least 1 prior treatment for ITP (suchas glucocorticoids, immunoglobulin) and have failed to respond or relapsed aftertreatment;

4. During screening period, the mean of two platelet counts must be < 30 × 10^9/L, withnone >35 × 10^9/L;

5. Fully understand and are able to comply with the requirements of the protocol,voluntarily participate and sign the informed consent form.

Key Exclusion Criteria:

1. History of bone marrow stem cell disorder. Any abnormal bone marrow findings otherthan typical of ITP.

2. Any active malignancy. If prior history of cancer other than basal cell carcinoma orcervical carcinoma in situ, no treatment or active disease within 5 years prior tosigning the ICF.

3. Diagnosed with arterial thrombotic disease (such as cerebral thrombosis, transientischemic attack, myocardial infarction, peripheral arterial disease, etc.); Patientswith a history or complications of venous thrombosis (such as deep vein thrombosis,pulmonary embolism); or patients who are using anticoagulants or antiplatelet drugsat the beginning of screening.

4. Subjects who have used romiplostim or its analogs in the past and have notresponded.

5. Subjects who have used eltrombopag, haitubopag, avatubopag, recombinant humanthrombopoietin (rhTPO), or other drugs with c-MPl stimulating effects within the 4weeks prior to signing the ICF.

6. Received any anti-malignancy agents (e.g., cyclophosphamide, mercaptopurine,vincristine, vinblastine, interferon-alfa) within 8 weeks prior to signing the ICF.

7. Less than 4 weeks since end of any clinical trials about therapeutic drug or deviceprior to signing the ICF.

8. Laboratory abnormalities with clinical significance at screening visit.

9. In the opinions of investigators, the patients are not suitable for participation inthis trial.