The latest developments on the gene therapy frontier
Twenty-one years ago this September, Jesse Gelsinger died after receiving an experimental gene therapy in a clinical trial seeking a cure for the rare disease he inherited.
His death reverberated throughout the scientific community, spurring investigations of the University of Pennsyvlania center that conducted the study. Gene therapy development, which had been charging ahead on the promise of replacing faulty genes, slowed considerably.
Two decades later, the technology is again at the forefront of biomedical research, catalyzed by advances in safer delivery of genes to cells.
Two genetic fixes for inherited diseases have won U.S. approval, one for a type of childhood blindness and the other for a fatal neuromuscular condition. By one count, nearly 300 experimental gene-based therapies are in clinical testing, including one aimed at OTC deficinecy, the disease from which Gelsinger suffered.
By 2025, the Food and Drug Administration expects it will be clearing 10 to 20 cell and gene therapy products a year.
Along with progress have come setbacks, though. This year, three patients with a rare neuromuscular disorder died due to liver complications in a trial of an experimental gene therapy, a tragedy that brought with it echoes of Gelsinger's death. In August, a hemophilia gene therapy that was widely expected to win U.S. approval was rejected by the FDA, which asked for more data from developer BioMarin Pharmaceutical.
And while the arrival of gene therapy's moment may be clear, its effects on a healthcare system designed around chronic treatment are not. The two medicines now approved cost $850,000 and $2.1 million per patient, respectively, and those advancing through development are expected to command similar price tags.
Gene therapy's promise of a cure, meanwhile, can only be hinted at through studies lasting years, or possibly even decades.
Science may also move quickly past gene replacement therapy to gene editing via CRISPR and other methods, an approach in which the unknowns are even greater and clinical work has just begun.
