BIVV003 + ST-400

**BIVV003 + ST-400** is a combination of two experimental autologous gene-edited hematopoietic stem cell therapies developed using zinc finger nuclease (ZFN) technology. Both BIVV003 and ST-400 use ex vivo ZFN-mediated gene editing of the erythroid enhancer region of the BCL11A gene in CD34+ hematopoietic stem and progenitor cells. This modification suppresses the production of pathologic hemoglobin and reactivates fetal hemoglobin (HbF) production. BIVV003 is being investigated primarily for severe sickle cell disease (SCD), aiming to reduce sickled hemoglobin and vaso-occlusive crises. ST-400 is targeted for transfusion-dependent beta-thalassemia (TDT), intending to ameliorate ineffective erythropoiesis and anemia. Both therapies utilize the patient’s own edited stem cells, which are infused after conditioning to engraft and produce healthy red blood cells.