A prime editing strategy to rewrite the γ-globin promoters and reactivate fetal hemoglobin for sickle cell disease

Fetal hemoglobin reactivation is a promising therapy for β-hemoglobinopathies. We developed a prime editing strategy that introduces multiple mutations in the fetal γ-globin promoters that are expected to increase their activity. We tested multiple targets and optimized a variety of parameters to achieve ∼50% of precise edits in a hematopoietic cell line, with minimal off-target effects. This work improved our understanding of the complex DNA repair mechanisms involved in prime editing. We tested this strategy in patients' hematopoietic stem/progenitor cells. Although editing efficiency was variable among donors, erythroid clones carrying multiple mutations expressed a significantly higher γ-globin level than cells carrying individual mutations, confirming the potential therapeutic benefit of our combined strategy for patients with β-hemoglobinopathies.