Clinical Trial Landscape of Gene-Edited Autologous Hematopoietic Stem Cells for Hemoglobinopathies and Immunodeficiencies.

Allogeneic hematopoietic cell transplantation (HCT) has been used for decades to treat certain malignant and non-malignant hematological conditions, but challenges remain. Increased understanding of disease mechanisms and recent developments in genome editing have enabled alternative strategies utilizing gene-edited autologous HCT and many of these have progressed to the clinic. We present here a comprehensive review of clinical trials of gene-edited autologous hematopoietic stem cells for the treatment of hemoglobinopathies and immunodeficiencies. Searches of major international clinical trial registries were carried out using specific key words. In total, 44 interventional clinical trials investigating gene-edited autologous stem cell therapies were identified, with CASGEVY (exagamglogene autotemcel) being the only product approved to date. Hemoglobinopathies were the most common indication (n = 37) followed by immunodeficiencies (n = 4), with single trials in HIV-1 infection, pyruvate kinase deficiency and limb-girdle muscular dystrophy. Gene-editing strategies fall into three categories: disruption of the BCL11A erythroid enhancer, editing of the γ-globin promoter and direct correction or disruption of disease-relevant genes. CD34+ hematopoietic stem and progenitor cells are the most common cell types edited, and CRISPR-Cas9 is the most widely used gene-editing modality. While results are encouraging, efficient intracellular delivery of gene-editing tools, editing efficiencies and off-target editing remain challenges for the field.