bluebird bio’s Skysona (elivaldogene autotemcel, also known as eli-cel) gene therapy has been granted accelerated approval by the US Food and Drug Association (FDA) to slow the progression of neurologic dysfunction in boys four to 17 years old with early, active cerebral adrenoleukodystrophy (CALD), the company announced.
CALD is a rare, progressive, neurodegenerative disease that primarily affects young children and leads to irreversible loss of neurologic function and death, with nearly half of patients who do not receive treatment dying within five years of symptom onset.
Prior to the approval of Skysona, effective options were limited to allogeneic hematopoietic stem cell transplant (allo-HSCT). This stabilises neurologic function, but is associated with serious potential complications and mortality that increase in patients without a matched sibling donor.
The FDA’s decision was based on data from the company’s phase 2/3 and phase 3 studies. Both open-label, single-arm studies monitored patients treated with Skysona for the emergence of six major functional disabilities (MFDs) associated with CALD progression including loss of communication, cortical blindness, requirement for tube feeding, total incontinence, wheelchair dependence, or complete loss of voluntary movement.
Skysona treated patients had an estimated 72% likelihood of MFD-free survival at 24 months, compared to 43% for untreated patients in a natural history control group.
As a condition of the accelerated approval, bluebird bio has agreed to provide confirmatory long-term clinical data to the FDA, which the company anticipates will include data from the ongoing long-term follow-up study (LTF-304), which follows patients treated in clinical trials for 15 years, and from commercially treated patients.
Andrew Obenshain, chief executive officer, bluebird bio, said: “Children with CALD and their families have been at the heart of bluebird’s mission since the company was founded more than a decade ago.
“For the ALD community, this long-awaited approval represents significant hope and offers families a new option where, for many, there had been none. We are grateful to every individual who was involved in the development of Skysona and are committed to working with providers and payers to make this important treatment option available to patients and their families.”
The company also confirmed that the previous clinical hold on the eli-cel clinical development programme has been lifted, which was put in place after a patient developed myelodysplastic syndrome (MDS), a type of blood cancer, after administration of Skysona.
Altogether, three patients in Skysona’s clinical programme showed MDS, which is believed to be related to the lentiviral vector used to deliver the gene.