This study aims to evaluate the efficacy and safety of Ripertamab in combination with Eltrombopag compared to Eltrombopag alone for patients with Primary Immune Thrombocytopenia (ITP) who have not responded to or have relapsed after first-line steroid therapy. Participants will be randomly assigned to one of two treatment groups and followed for 52 weeks to assess response rates and safety.

This is a multicenter, open-label, randomized controlled clinical trial designed to compare the effects of Ripertamab plus Eltrombopag versus Eltrombopag monotherapy in adults with ITP. The study will enroll approximately 78 participants, aged 18 to 80 years, who have had an inadequate response to or relapsed after first-line steroid therapy. The primary outcome measure is the sustained response rate at 12 weeks post-treatment initiation. Secondary outcomes include overall response rate, complete response rate, median time to response, median sustained response time, and safety. Participants will undergo regular blood tests and clinical assessments throughout the study period.

Inclusion Criteria:

1. Diagnosis: Confirmed Primary Immune Thrombocytopenia (ITP) with an age range of 18 to 80 years, inclusive, and no gender restrictions.
2. Bone Marrow Cytology: Diagnosis via bone marrow cytology excluding secondary thrombocytopenia caused by other diseases, with primary ITP patients who are unresponsive to or have relapsed after first-line steroid therapy (platelet count drops below 30×10^9/L).
3. Coagulation Status: Laboratory tests show prothrombin time (PT/INR) and activated partial thromboplastin time (APTT) not exceeding 20% above the upper limit of normal values, with no history of coagulation disorders other than ITP.
4. Bone Marrow Function: Normal bone marrow function indicated by an absolute neutrophil count (ANC) ≥1.5×10^9/L and hemoglobin (Hb) ≥90 g/L.

Liver and Kidney Function: Normal liver and kidney function with serum direct bilirubin and indirect bilirubin ≤1.5 times the upper limit of normal (ULN); 5.alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤3 times the upper limit of normal (ULN); serum creatinine ≤1.5 times the upper limit of normal (ULN).

6.Psychiatric History: No history of psychiatric disorders. 7.Informed Consent: Voluntary signing of an informed consent form.

Exclusion Criteria:

1. Life-Threatening Bleeding: Presence of bleeding that poses an immediate threat to life, such as severe anemia or central nervous system bleeding.
2. Recent Treatment: Use of intravenous immunoglobulin, thrombopoietin receptor agonists, recombinant human thrombopoietin (rhTPO), immunosuppressants, anti-CD20 monoclonal antibodies, or systemic corticosteroids within 28 days prior to enrollment.
3. Malignancy History: History of malignancy.
4. Cardiac Conditions: Presence of severe heart failure or other diseases significantly impacting cardiac function (e.g., unstable angina, congestive heart failure, uncontrolled hypertension, arrhythmias, or prolonged QTc interval within the last 3 months).
5. Coagulation Disorders: History of coagulation disorders other than ITP, such as disseminated intravascular coagulation (DIC), hemolytic uremic syndrome (HUS), or thrombotic thrombocytopenic purpura (TTPP).
6. Viral Markers: Hepatitis C virus (HCV) antibody positive with HCV RNA quantitative test ≥10^4 copies/mL; or Hepatitis B virus (HBV) markers positive for HBsAg and/or HBcAb with HBV DNA positivity.
7. Immunocompromised: History of immunodeficiency, including HIV positivity or other acquired or congenital immunodeficiency diseases, autoimmune diseases, or a history of organ transplantation.
8. Tuberculosis: Suspected active or latent tuberculosis.
9. Active Infections: Presence of active infections at enrollment, or any significant infectious events within 4 weeks prior to enrollment or major surgery within 4 weeks.
10. Pregnancy and Lactation: Pregnant or nursing women, or women of childbearing potential or considering pregnancy during the study period.
11. Other Conditions: Any other conditions deemed by the investigator as contraindications for study participation.