ZS801

ZS801 is a novel, bioengineered adeno-associated viral (AAV) vector-based gene therapy designed to deliver a functional human factor IX (F9) gene variant. Its primary mechanism is the in vivo transfer of the F9 gene to liver cells, enabling endogenous production of factor IX protein in patients with hemophilia B—a congenital bleeding disorder caused by factor IX deficiency. The therapy aims for long-term correction of coagulation defects through a single intravenous infusion. ZS801 is being developed by Sichuan Real & Best Biotech and has reached Phase 1/2 clinical trials in China for adult patients with moderate to severe hemophilia B[1][2][3][4][5].