Gene Therapy of Beta Hemoglobinopathies.

Background/Objectives: Sickle cell disease (SCD) and β-thalassemia are autosomal recessive disorders of erythroid cells due to gene mutations occurring at the level of the β-globin gene. The severe forms of these hemoglobinopathies observed in individuals homozygous for these defective genes need intensive treatments, are associated with a poor quality of life, and allogeneic hematopoietic stem cell represents the only curative treatment option that can be offered to a limited proportion of patients. Methods: This work is a narrative review supported by a systematic literature search and analysis. Results: To bypass this limitation, autologous hematopoietic stem cell transplantation has been developed in these patients, in which patients' HSCs are harvested and genetically modified ex vivo, then transplanted back into patients after conditioning for stem cell transplantation. There are two different approaches for gene therapy of hemoglobinopathies, one based on gene addition or gene silencing using lentiviruses as vectors and the other based on gene editing strategies using CRISPR-Caspase 9 technology or base editing. Several gene therapy products have been successfully evaluated in these patients, achieving transfusion independence and correction of hematological abnormalities durable over time. Conclusions: Several gene therapy products have been approved for the treatment of SCD and β-thalassemic patients and offer potentially curative treatment for these patients.