The main aim of this clinical trial is to assess the safety and efficacy of a single dose of PN20 in treatment of thrombocytopenia in adult patients with chronic liver disease undergoing an elective procedure. The main questions it aims to answer are:

• How effective is PN20 in treating thrombocytopenia in patients with chronic liver disease?
• Is PN20 safe in these patients? Participants will
• Receive a single subcutaneous injections of PN20 or placebo according to weight before an elective procedure,
• Visit the clinic for assessment.

This is aan open-label, single-dose, dose-escalation phase Ib/II study conducted in two stages, Phase Ib and Phase II, designed to evaluate the safety, tolerability, efficacy, PK, PD, and immunogenicity of PN20 in patients with CLDT in patients with CLDT.

Phase Ib stage is an open-label, single-dose, dose-escalation study. Three dose levels (8 participants per group) will be administered sequentially from low to high.

Phase 2 stage is a randomized, double-blind, single-dose, placebo-controlled study. Eligible patients are randomized in a 1:1 ratio to the treatment or placebo group following informed consent. The dosing regimen in the treatment group is selected based on the Phase Ib results, with one or two dose levels selected. If two PN20 dose levels are selected, randomization follows a 1:1:1 ratio to one of the two treatment groups or to the placebo group.

Inclusion Criteria:

• Age ≥ 18 years, Male or female
• Diagnosed with chronic liver disease-related thrombocytopenia (baseline platelet count < 50 × 10⁹/L), Child-Pugh score A or B;
• Planned elective invasive procedure or minor surgery within Days 7-15 post-enrollment, excluding laparotomy, thoracotomy, craniotomy, open-heart surgery, organ resection, or partial organ resection (for tissue biopsy and other types of tissue resection, enrollment is permitted if the investigator considers the risk of bleeding and invasiveness to be comparable to or lower than that of the procedures listed in the surgical examples list);
• Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1;
• Women of childbearing potential must have a negative pregnancy test
• Agree to use reliable contraception through 3 months post-study.
• Participants must understand the study requirements and provide written informed consent.

Exclusion Criteria:

• The following conditions or medical history:

  • Presence of other conditions that may lead to thrombocytopenia;
  • History of thrombotic or significant cardiovascular events;
  • Uncontrolled bleeding;
  • Advanced liver cancer;
  • Severe comorbidities;

• Currently using or with a history of the following treatments:

  • Recent major surgery or splenectomy;
  • Liver transplant;
  • Recent therapies affecting platelet counts;

• Significant lab abnormalities;

• Recent participation in other clinical trials;

• Known hypersensitivity to the investigational productstudy drug；

• Active substance abuse;

• Any condition deemed by the investigator to compromise safety or study integrity.