The #β-hemoglobinopathies #β-
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 β-
globin chain of the adult
hemoglobin (Hb)
tetramer. Here, the inventors intend to improve HSC-based
gene therapy for β-
thalassemia and SCD by developing an innovative, highly infectious LV vector expressing a potent anti-sickling β-
globin transgene and a second biological function either increasing fetal γ-
globin expression (for β-
thalassemia and SCD). More particularly, the inventors have designed a novel
lentivirus (LV), which carry two different functions: βAS3
gene addition and
gene silencing. This last strategy allows the re-expression of the fetal γ-
globin genes (HBG1 and HBG2) and production of the endogenous fetal
hemoglobin (HbF). Elevated levels of HbF and HbAS3 (Hb
tetramer containing βAS3-globin) will benefit the β-
hemoglobinopathy phenotype by increasing the total amount of β-like globin that will: (i) reduce the alpha precipitates and improve the alpha / non alpha ratio in β-thalassemia, and (ii) reduce the sickling in SCD. This combined strategy will improve the β-
hemoglobinopathy phenotype at a lower vector copy number (VCN) per
cell compared to a LV expressing the βAS3 alone.