A Prospective, Multicenter, Single-Arm Study: Safety and Efficacy of Iptacopan in the Treatment of High-Risk Hematopoietic Stem Cell Transplantation-Associated Thrombotic Microangiopathy (TA-TMA)
The goal of this clinical trial is to evaluate the efficacy and safety of Iptacopan as a second-line treatment for high-risk hematopoietic stem cell transplantation-associated thrombotic microangiopathy (TA-TMA). Iptacopan is a selective oral small-molecule complement factor B inhibitor. It acts by inhibiting factor B, blocking the formation of C3 convertase, reducing C3b deposition, thereby suppressing C5 convertase (C3bBbC3b) and ultimately decreasing the formation of the membrane attack complex (MAC), which is expected to mitigate endothelial damage in TA-TMA pathology. The main questions this study aims to answer are: * Does Iptacopan improve 6-month overall survival in high-risk TA-TMA patients? * What adverse events do participants experience while taking Iptacopan? * Does Iptacopan provide hematological response and organ function recovery in TA-TMA patients? In this prospective, multicenter, open-label, single-arm Phase II study, all participants will receive Iptacopan treatment. The primary endpoint of this study is the 6-month overall survival rate from TA-TMA diagnosis. Secondary endpoints include safety evaluation, hematological response, and organ function recovery. During the study, participants will: * Receive Iptacopan treatment according to protocol * Undergo regular assessments for safety and efficacy monitoring * Be followed for up to 24 months post-treatment initiation
• Age ≥12 years at the time of ICF signature.
• Previous recipient of autologous or allogeneic HSCT.
• Persistent TA-TMA despite initial management of potential triggers (e.g., CNI/mTOR inhibitor reduction, infection or GVHD treatment), with TMA activity sustained for ≥72 hours post-intervention.
• TA-TMA diagnosis, confirmed ≤14 days prior to or during screening by either biopsy-proven microthrombi or ≥4 of the following:
⁃ (1) LDH \> ULN (2) Proteinuria (rUPCR ≥1 mg/mg) (3) Hypertension (age-adjusted) (4) New-onset thrombocytopenia (platelet decrease ≥50%, count ≤50,000/mm³, or transfusion-refractory) (5) New-onset anemia or increased transfusion need (6) Microangiopathy on blood smear (schistocytes ≥1%) or biopsy (7) Elevated terminal complement complex (C5b-9) 5. High-risk TMA features (per 2023 consensus), meeting ≥1 criterion:
• LDH ≥2× ULN
• Elevated sC5b-9
• Proteinuria (rUPCR ≥1 mg/mg)
• Multi-organ dysfunction syndrome (MODS)
• Concurrent Grade II-IV acute GVHD
• Active systemic infection 6. Able to receive oral medication. 7. Failure of first-line therapy (e.g., CNI/mTOR inhibitor adjustment, plasma exchange, rituximab, defibrotide), excluding prior complement inhibitors.
⁃ 8\. Life expectancy \>8 weeks. 9. Required vaccination against encapsulated bacteria (meningococcal, pneumococcal) per local guidelines, administered ≥2 weeks prior to first dose. If vaccination is delayed, antimicrobial prophylaxis is required.
⁃ 10\. For subjects unable to receive meningococcal vaccines, antibiotic prophylaxis must be continued throughout treatment and for 8 months post-last dose.
⁃ 11\. For subjects of reproductive potential: agreement to use effective contraception and, for females, a negative pregnancy test at screening.
⁃ 12\. Provision of signed informed consent and compliance with study procedures.