Development of β-globin gene correction in human hematopoietic stem cells as a potential durable treatment for sickle...

Area of Science:

• Hematology
• Gene Therapy
• Molecular Biology

Background:

• Sickle cell disease (SCD) is a prevalent, serious monogenic disorder affecting 300,000 newborns annually worldwide.
• SCD arises from a specific point mutation in the beta-globin gene (HBB), leading to autosomal recessive inheritance.
• Ex vivo gene correction of autologous hematopoietic stem and progenitor cells (HSPCs) offers a potential curative treatment pathway for SCD.

Purpose of the Study:

• To demonstrate the preclinical feasibility, efficacy, and safety of CRISPR-Cas9 mediated HBB gene correction in patient-derived HSPCs.
• To evaluate the therapeutic potential of the gene-corrected HSPCs (gcHBB-SCD) for sickle cell disease treatment.

Main Methods:

• Utilized a CRISPR-Cas9 system with high-fidelity Cas9 and chemically modified guide RNAs for precise HBB gene targeting.
• Employed recombinant adeno-associated virus serotype 6 (rAAV6) for efficient gene delivery and correction in HSPCs.
• Assessed gene correction efficiency, multilineage engraftment, and long-term safety, including tumorigenicity and genotoxicity, in preclinical models.

Main Results:

• Achieved up to 60% HBB allelic correction in clinical-scale manufacturing of gcHBB-SCD.
• Demonstrated 20% gene correction with successful multilineage engraftment after transplanting gcHBB-SCD into NSG mice.
• Long-term studies revealed no evidence of abnormal hematopoiesis, genotoxicity, or tumorigenicity in engrafted cells.

Conclusions:

• Preclinical data strongly support the safety, efficacy, and reproducibility of this CRISPR-Cas9 based HBB gene correction strategy.
• The findings provide a solid foundation for advancing this gene therapy approach towards a Phase 1/2 clinical trial for SCD patients.