Gene therapy is a new medical breakthrough which has, in reality, been several decades in the making. The concept was first suggested 50 years ago as a possibility for targeted treatments, but it was not until late 2017 that the first gene therapy, Luxturna, was approved by the U.S. Food and Drug Administration (FDA). 

At the rate research and approvals have been accelerating, the 2020s may be remembered as the decade when the number and scope of gene therapy treatments expanded substantially. As of late May 2024, 14 gene therapies are FDA-approved for a range of conditions including sickle cell disease, hemophilia A and B, Duchenne muscular dystrophy, beta thalassemia, and metachromatic leukodystrophy. Nine of these approvals have come since August 2022, and currently in the U.S., more than 600 gene therapy trials are actively recruiting patients. This rapid pace is expected to continue, with at least three more approvals expected by the end of 2024 and dozens more anticipated by the end of the decade. 

Now that gene therapies have been around for more than five years, durability and efficacy information is beginning to emerge. Luxturna® (voretigene neparvovec), which treats an inherited retinal disease that progresses to blindness, has thus far had good durability statistics. A surprise, however, has been Zolgensma® (onasemnogene abeparovec), available since 2019 to treat spinal muscular atrophy. Early statistics indicate that its durability of response has not been as robust as expected, with many patients requiring ongoing support from additional high-cost drugs such as Spinraza®.