Coordinated β-globin expression and α2-globin reduction in a multiplex lentiviral gene therapy vector for β-thalassemia

• Published in: Molecular therapy Vol. 29; no. 9; pp. 2841 - 2853
• Main Authors: Nualkaew, Tiwaporn, Sii-Felice, Karine, Giorgi, Marie, McColl, Bradley, Gouzil, Julie, Glaser, Astrid, Voon, Hsiao P.J., Tee, Hsin Y., Grigoriadis, George, Svasti, Saovaros, Fucharoen, Suthat, Hongeng, Suradej, Leboulch, Philippe, Payen, Emmanuel, Vadolas, Jim
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2021; American Society of Gene & Cell Therapy
• Subjects: alpha-Globins - genetics; BB305; beta-Globins - genetics; beta-Thalassemia - genetics; beta-Thalassemia - therapy; Cell Line; Cells, Cultured; Down-Regulation; Erythroid Cells - cytology; Erythroid Cells - metabolism; gene therapy; Genetic Vectors - administration & dosage; Genotype; globin; hemoglobin disorder; Humans; insertional mutagenesis; K562 Cells; lentiviral vector; Lentivirus - genetics; Lentivirus - physiology; LVβ-shα2; MicroRNAs - antagonists & inhibitors; Original; Primary Cell Culture; RNA inteference; RNA, Small Interfering - genetics; shRNAmir; thalassemias; Viral Load; shRNAmir; insertional mutagenesis; LVβ-shα2; globin; BB305; gene therapy; thalassemias; RNA inteference; hemoglobin disorder; lentiviral vector
• ISSN: 1525-0016; 1525-0024
• DOI: 10.1016/j.ymthe.2021.04.037

A primary challenge in lentiviral gene therapy of β-hemoglobinopathies is to maintain low vector copy numbers to avoid genotoxicity while being reliably therapeutic for all genotypes. We designed a high-titer lentiviral vector, LVβ-shα2, that allows coordinated expression of the therapeutic βA-T87Q-globin gene and of an intron-embedded miR-30-based short hairpin RNA (shRNA) selectively targeting the α2-globin mRNA. Our approach was guided by the knowledge that moderate reduction of α-globin chain synthesis ameliorates disease severity in β-thalassemia. We demonstrate that LVβ-shα2 reduces α2-globin mRNA expression in erythroid cells while keeping α1-globin mRNA levels unchanged and βA-T87Q-globin gene expression identical to the parent vector. Compared with the first βA-T87Q-globin lentiviral vector that has received conditional marketing authorization, BB305, LVβ-shα2 shows 1.7-fold greater potency to improve α/β ratios. It may thus result in greater therapeutic efficacy and reliability for the most severe types of β-thalassemia and provide an improved benefit/risk ratio regardless of the β-thalassemia genotype. [Display omitted] Nualkaew et al. show that LVβ-shα2 reduces α2-globin mRNA expression in erythroid cells while keeping α1-globin mRNA levels unchanged and βA-T87Q-globin gene expression identical to the parent vector. Compared with the first βA-T87Q-globin lentiviral vector that has received conditional marketing authorization, BB305, LVβ-shα2 shows 1.7-fold greater potency to improve α/β ratios. It may thus result in greater therapeutic efficacy and reliability for the most severe types of β-thalassemia and provide an improved benefit/risk ratio regardless of the β-thalassemia genotype.