FDA Approves Expaneded Use of Vertex’s SCD Gene Therapy

Rare Daily Staff

The U.S. Food and Drug Administration has approved an expanded label for Vertex Pharmaceuticals gene-editing therapy Casgevy, allowing its use in children as young as 2 years old with sickle cell disease or transfusion-dependent beta thalassemia.

The decision significantly broadens access to the one-time treatment, which was previously cleared only for patients aged 12 and older.

The approval makes Casgevy the first genetic therapy authorized for both conditions in very young children, potentially adding about 5,500 newly eligible patients in the United States. Vertex said it has already established more than 75 authorized treatment centers nationwide to deliver the therapy, which requires specialized cell collection and transplantation procedures. Regulatory reviews to expand pediatric use are also underway in the United Kingdom and Saudi Arabia.

Physicians and patient advocates have long emphasized the importance of earlier intervention in these inherited blood disorders, where cumulative organ damage begins in early childhood.

Sickle cell disease and transfusion-dependent beta thalassemia are rare, inherited disorders that affect hemoglobin, the protein in red blood cells that carries oxygen. In sickle cell disease, red blood cells become rigid and misshapen, blocking blood flow and triggering painful episodes known as vaso-occlusive crises, along with progressive damage to organs such as the brain, lungs, and kidneys. In transfusion-dependent beta thalassemia, the body cannot produce enough functional hemoglobin, forcing patients to rely on lifelong blood transfusions and iron chelation therapy, which themselves can lead to serious complications over time.

Both conditions place a heavy burden on patients and families, often beginning in early childhood and shortening life expectancy despite existing treatments. In the United States, median survival is estimated at roughly 45 years for sickle cell disease and 37 years for transfusion-dependent beta thalassemia, with lifetime medical costs reaching into the millions of dollars.

Casgevy is a CRISPR/Cas9-based gene-editing therapy designed as a one-time treatment using a patient’s own stem cells. Doctors collect blood-forming stem cells from the patient, edit them outside the body to disable a genetic switch known as BCL11A, and then reinfuse the modified cells after chemotherapy conditioning. This edit reactivates production of fetal hemoglobin, a form of hemoglobin that is naturally present before birth and can compensate for the defective adult version.

In clinical trials, the therapy has shown the ability to eliminate or sharply reduce painful crises in sickle cell disease and to free many beta thalassemia patients from the need for regular transfusions. Patients are being followed in long-term studies for up to 15 years to better understand durability and safety.

The treatment carries risks associated with stem cell transplantation and gene editing, including severe short-term side effects such as low blood counts and infection risk, and the theoretical possibility of unintended genetic changes. Still, all treated patients in clinical studies achieved key milestones such as neutrophil engraftment.

“Just as we redefined what is possible in cystic fibrosis, our ambition is to transform the future for people living with sickle cell disease and transfusion-dependent beta thalassemia,” said Reshma Kewalramani, president and CEO of Vertex. “The remarkable consistency of results across age groups reinforces the potential of Casgevy to deliver durable, transformative benefits to those who have historically had limited options.”