Romiplostim for Oral TPO-RA Resistant ITP

Inclusion Criteria: Age ≥18 years Diagnosed with primary immune thrombocytopenia (ITP) according to current guidelines Failed prior oral TPO-RA therapy (eltrombopag, hetrombopag, or avatrombopag), defined as: Platelet count persistently \<30×10⁹/L after ≥4 weeks of treatment at the maximum recommended or tolerated dose, OR Prior achieved response (platelet ≥50×10⁹/L) then lost response with platelet count \<30×10⁹/L on two consecutive visits (≥1 week apart), OR Intolerance to oral TPO-RA leading to discontinuation (with documented reason) Baseline platelet count \<30×10⁹/L (at least two measurements, ≥5 days apart) ECOG performance status 0-2 Willing and able to receive weekly subcutaneous injections and comply with study procedures For women of childbearing potential: negative pregnancy test at screening and agreement to use effective contraception during the study and for 3 months after the last dose Able to provide written informed consent Exclusion Criteria: Secondary ITP (e.g., associated with autoimmune diseases, lymphoproliferative disorders, drug-induced, or infections such as HIV/HCV/HBV) Known hypersensitivity to romiplostim or any of its excipients Prior treatment with romiplostim Received rituximab or other B-cell depleting therapy within 6 months prior to screening Received immunosuppressants (e.g., cyclosporine, mycophenolate mofetil, azathioprine, danazol) within 4 weeks prior to screening Splenectomy within 8 weeks prior to screening Use of corticosteroids (prednisone \>10 mg/day or equivalent) or IVIG within 2 weeks prior to screening History of bone marrow fibrosis (MF grade ≥2) or known reticulin fibrosis History of arterial or venous thromboembolic event (e.g., myocardial infarction, stroke, deep vein thrombosis, pulmonary embolism) within 6 months prior to screening Known thrombophilic conditions (e.g., antiphospholipid syndrome, protein C/S deficiency, ATIII deficiency) Severe hepatic impairment (ALT or AST \>3×ULN, or total bilirubin \>1.5×ULN) Severe renal impairment (creatinine clearance \<30 mL/min) New York Heart Association (NYHA) functional class III or IV heart failure Malignancy within 5 years prior to screening (except non-melanoma skin cancer, cervical carcinoma in situ, or ductal carcinoma in situ of the breast) Pregnancy or breastfeeding Participation in another interventional clinical trial within 30 days prior to screening Any other condition that, in the investigator's judgment, would make the participant unsuitable for the study