Abstract: Gene therapy of SCO is based on the transplantation of genetically modified HSCs. Several LV approaches based on gene addition consist in transducing patient HSCs with a lentiviral vector expressing an anti-sickling ?-like globin chain such as use of ?AS3 HBB anti-sickling variants. Here, the inventors have improved the design of the LV-AS3 vector to treat SCO patients. These LVs allow the simultaneous expression of the potent anti-sickling ?AS3-globin and an artificial miR (amiR) silencing the ?S-globin. The reduction of ?S-globin levels will increase the incorporation of ?AS3-globin in Hb tetramers, which should increase the proportion of corrected RBCs in SCO patients. The inventors selected the best-performing miRs, and modified the therapeutic ?AS3-globin transgene by inserting silent mutations to avoid the recognition by the amiR and the silencing of the transgene.

Abstract: The #?-hemoglobinopathies #?-thalassemia (BT) and sickle cell disease (SCD) are the most frequent genetic disorders worldwide. These diseases are caused by mutations causing reduced or abnormal synthesis of the ?-globin chain of the adult hemoglobin (Hb) tetramer. Here, the inventors intend to improve HSC-based gene therapy for ?-thalassemia and SCD by developing an innovative, highly infectious LV vector expressing a potent anti-sickling ?-globin transgene and a second biological function either increasing fetal ?-globin expression (for ?-thalassemia and SCD). More particularly, the inventors have designed a novel lentivirus (LV), which carry two different functions: ?AS3 gene addition and gene silencing. This last strategy allows the re-expression of the fetal ?-globin genes (HBG1 and HBG2) and production of the endogenous fetal hemoglobin (HbF).