Context base editing for splice correction of IVSI-110 β-thalassemia

Area of Science:

• Genetics
• Molecular Biology
• Hematology

Background:

• Beta-thalassemia results from defective beta-globin production, necessitating transfusions and chelation.
• Genome editing in hematopoietic stem cells offers a curative approach for beta-thalassemia.
• Base editors (BEs) provide precise DNA editing with potentially reduced risks compared to double-strand-break methods.

Purpose of the Study:

• To evaluate two adenine base editors (ABEs), SpRY and SpG, for correcting the common HBB splice mutation.
• To characterize the on-target editing profile and efficiency of ABEs in patient-derived cells.

Main Methods:

• Recalibration and re-cloning of SpRY and SpG adenine base editors.
• Nucleofection of ABE components as RNA into patient-derived CD34+ cells.
• Analysis of on-target base editing, insertions/deletions, and functional correction at RNA, protein, and differentiation levels.

Main Results:

• Achieved up to 90% editing of HBB splice mutation elements.
• Detailed characterization of on-target editing profiles, including insertion/deletion differences.
• Identified context-dependent effects on splice correction and BE editing event distributions.
• Demonstrated high-efficiency functional correction of HBB mutation.

Conclusions:

• Adenine base editors (SpRY and SpG) effectively correct the HBB splice mutation in patient cells.
• This base editing strategy shows promise for functional restoration of beta-globin production.
• BEs represent a viable and potentially safer alternative for beta-thalassemia gene therapy.