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.© 2025 American Society of Hematology. Published by Elsevier Inc. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.