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

This is a multicenter, open-label, single-arm, dose-escalation Phase1b study aimed at evaluating the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), immunogenicity, and preliminary efficacy of a single dose of PN20 in adult patients with primary immune thrombocytopenia (ITP).

The trial is a dose escalation study, including Screening (no more than 14 days), Treatment (single dose) and the post-treatment follow-up (4 weeks).

And the safety, tolerability, pharmacokinetics, pharmacodynamics, immunogenicity, and preliminary efficacy of PN20 in ITP will be assessed in this study.

Key Inclusion Criteria:

• Aged between 18 and 65 years (inclusive), male or female;
• Diagnosed with primary immune thrombocytopenia (ITP) and have a disease course of more than 6 months;
• Patients who have no response or relapsed after splenectomy. Or patients who have not been splenectomised and have completed at least 1 prior treatment for ITP (such as glucocorticoids, immunoglobulin) and have failed to respond or relapsed after treatment;
• During screening period, the mean of two platelet counts must be < 30 × 10^9/L, with none >35 × 10^9/L;
• Fully understand and are able to comply with the requirements of the protocol, voluntarily participate and sign the informed consent form.

Key Exclusion Criteria:

• History of bone marrow stem cell disorder. Any abnormal bone marrow findings other than typical of ITP.
• Any active malignancy. If prior history of cancer other than basal cell carcinoma or cervical carcinoma in situ, no treatment or active disease within 5 years prior to signing the ICF.
• Diagnosed with arterial thrombotic disease (such as cerebral thrombosis, transient ischemic attack, myocardial infarction, peripheral arterial disease, etc.); Patients with a history or complications of venous thrombosis (such as deep vein thrombosis, pulmonary embolism); or patients who are using anticoagulants or antiplatelet drugs at the beginning of screening.
• Subjects who have used romiplostim or its analogs in the past and have not responded.
• Subjects who have used eltrombopag, haitubopag, avatubopag, recombinant human thrombopoietin (rhTPO), or other drugs with c-MPl stimulating effects within the 4 weeks prior to signing the ICF.
• Received any anti-malignancy agents (e.g., cyclophosphamide, mercaptopurine, vincristine, vinblastine, interferon-alfa) within 8 weeks prior to signing the ICF.
• Less than 4 weeks since end of any clinical trials about therapeutic drug or device prior to signing the ICF.
• Laboratory abnormalities with clinical significance at screening visit.
• In the opinions of investigators, the patients are not suitable for participation in this trial.