CALD is a neurodegenerative disease primarily affecting young boys that leads to major functional disabilities and eventually death. Eli-cel stabilizes the progression of the disease and would represent the first therapy for CALD that uses a patient's own hematopoietic stem cells, according to Bluebird Bio.

The one-time investigational gene therapy drug is designed to add functional copies of the ABCD1 gene into a patient's own hematopoietic stem cells that have been transduced ex vivo with the Lenti-D lentiviral vector. The functional gene allows patients to produce the adrenoleukodystrophy protein, which is thought to break down the very-long-chain fatty acids that accumulate to toxic levels in the brain.

In July, the EMA's Committee for Medicinal Products for Human Use granted an accelerated assessment to eli-cel, which could reduce the EMA's active review time of the MAA from 210 days to 150 days. In addition, the U.S. Food and Drug Administration granted eli-cel orphan drug status, rare pediatric disease designation, and breakthrough therapy designation for the treatment of CALD.