Sickle Cell, Gene Therapy, and the Limits of Medical Triumph

Gene therapy has given sickle cell disease what medicine has long promised but rarely delivered: the possibility of a cure. Yet the slow uptake of Casgevy and Lyfgenia shows that even dazzling science can falter when it collides with cost, logistics, risks, and a medical system many patients distrust.

In December 2023, the FDA approved the first two gene therapies with curative potential for sickle cell disease (SCD): Casgevy, which uses CRISPR to edit a patient’s own stem cells, and Lyfgenia, which uses a viral vector to deliver a functional gene. For a disease as painful and disabling as sickle cell disease, one might have expected a rush toward treatment. Yet unlike the rapid public embrace of GLP-1 drugs, that rush has not materialized. Last year, only 64 patients received Casgevy, and about 100 received Lyfgenia. In the United States, more than 100,000 people live with sickle cell disease.