Hematopoietic Stem-Cell Gene Therapy for Cerebral Adrenoleukodystrophy

Area of Science:

• Genetics and Gene Therapy
• Neurology
• Pediatric Medicine

Background:

• X-linked adrenoleukodystrophy (X-ALD) results from ABCD1 gene mutations, causing ALD protein dysfunction.
• Cerebral X-ALD leads to demyelination, neurodegeneration, and potentially fatal loss of neurologic function.
• Allogeneic hematopoietic stem-cell transplantation is currently the only established treatment to halt disease progression.

Purpose of the Study:

• To evaluate the safety and efficacy of Lenti-D gene therapy in boys with early-stage cerebral X-ALD.
• To assess key clinical outcomes including survival, major functional disability, neurologic function, and MRI lesion progression.

Main Methods:

• A single-group, open-label, Phase 2-3 study enrolled boys with early-stage cerebral X-ALD and MRI evidence of disease.
• Treatment involved infusion of autologous CD34+ cells genetically modified with the elivaldogene tavalentivec (Lenti-D) lentiviral vector.
• Interim analysis assessed graft-versus-host disease, mortality, functional disability, neurologic status, and MRI changes, with a primary endpoint of survival and absence of major functional disability at 24 months.

Main Results:

• 17 boys received Lenti-D gene therapy, with a median follow-up of 29.4 months.
• All patients showed gene-marked cells, ALD protein expression, and no evidence of oncogenic integration or clonal expansion.
• 88% of patients (15/17) were alive and free of major functional disability, with no reported treatment-related death or graft-versus-host disease.

Conclusions:

• Lenti-D gene therapy presents a potential safe and effective alternative to allogeneic stem-cell transplantation for early-stage cerebral X-ALD.
• Further long-term follow-up is necessary to confirm response duration and safety.
• The study suggests a significant improvement in clinical outcomes for treated patients.