How it actually works (from https://www.fiercebiotech.com/biotech/little-protein-factory-could-regeneron-gene-therapy-restores-hearing-2-kids https://www.fierce

How it actually works (from https://www.fiercebiotech.com/biotech/little-protein-factory-could-regeneron-gene-therapy-restores-hearing-2-kids https://www.fiercebiotech.com/biotech/little-protein-factory... ) DB-OTO is a cell-selective AAV gene therapy for children with hearing loss stemming from a mutation to the otoferlin gene. The otoferlin protein is expressed in the sensory hair cells of the ear, which have tiny cilia that move as vibrations come into the ear. These cells help signal between the auditory nerve and the hair cells, passing information from the ear to the brain. Children born with this type of genetic hearing loss have the hair cells and can detect the signal coming into the ear. “But they can't get that message from the ear to the brain, basically, because otoferlin is critical to enable that communication,” Whitton explained. That’s where DB-OTO comes in. The adeno-associated viral vector delivers the gene therapy to the ear to provide a payload of cDNA that expresses the protein in the hair cells that are missing it. The hypothesis was that if they provided the gene, patients could eventually begin to hear on their own. Regeneron does not yet know how long the effect will last, but “rigorous” preclinical tests were done to get a sense of durability, according to Whitton. Since those hair cells targeted by the gene therapy do not turn over during a person’s lifetime, they believe the effect should be persist once restored. “The ones that you're born with are the ones you will have the rest of your life, so if we can create a little protein factory in those cells, make the protein that's missing, there's reason to believe that you could have long-term benefit,” Whitton said. Note this is not CRISPR, its more like just adding little chunks of DNA into the cell (which I think is called upregulation). 'Gene Therapy' can mean many other things apart from Crispr, there's a whole complicated pipeline of processes that can be targeted.