Casgevy, developed by Vertex Pharmaceuticals in partnership with CRISPR Therapeutics, made history in 2023 as the first FDA-approved therapy based on CRISPR gene-editing technology. The treatment is designed as a one-time intervention that modifies a patient’s own blood-forming stem cells to increase production of fetal hemoglobin, helping to reduce or eliminate the complications associated with these inherited blood disorders.

According to Vertex, the FDA’s latest approval could make the therapy available to approximately 5,500 additional pediatric patients in the United States. Earlier treatment may help prevent the progressive organ damage and other long-term complications that can develop in individuals living with SCD or TDT.

“Earlier access to the transformative potential of this therapy will allow clinicians and families to consider treatment before years of cumulative damage from these life-shortening diseases take hold,” said Haydar Frangoul, MD, medical director of the Sarah Cannon Transplant and Cellular Therapy Program at TriStar Centennial Children’s Hospital.

Clinical Data Supporting the Expansion

The expanded approval was supported by findings from ongoing phase 3 studies evaluating Casgevy in younger children.

In one trial involving 11 patients aged 5 to 12 years with sickle cell disease, all eight participants eligible for efficacy evaluation achieved the primary endpoint, remaining free from severe vaso-occlusive crises for at least 12 consecutive months.

A second phase 3 study enrolled 15 children in the same age range with transfusion-dependent beta thalassemia. Among the nine evaluable patients, eight achieved transfusion independence, with a median duration of approximately 20 months.

Vertex noted that the decision to extend eligibility to children as young as 2 years was informed not only by these clinical findings but also by the therapy’s established biological profile and accumulated evidence across age groups.

Potential Impact for Patients

The approval reflects growing confidence in Casgevy’s ability to deliver lasting benefits across a broad patient population. Earlier intervention may be particularly important in pediatric patients, as both sickle cell disease and beta thalassemia can cause irreversible complications over time, including damage to the heart, lungs, kidneys, and other organs.

Vertex President and CEO Reshma Kewalramani, MD, said the consistency of outcomes observed in clinical studies suggests the therapy has the potential to provide durable disease-modifying effects regardless of patient age.

Review Through FDA Priority Program

The label expansion was reviewed under the FDA’s Commissioner’s National Priority Voucher (CNPV) program, an initiative designed to accelerate regulatory review for select therapies considered strategically important. The program was introduced during the tenure of former FDA Commissioner Marty Makary, MD, with the goal of shortening review timelines for qualifying products.

Commercial Adoption Continues to Grow

Despite the promise of potentially curative gene therapies, adoption has been gradual across the market. Casgevy and bluebird bio’s Lyfgenia—another gene therapy approved for sickle cell disease on the same day in 2023—have faced challenges related to treatment complexity and high costs. Casgevy carries a price tag of approximately $2.2 million, while Lyfgenia is priced at around $3.1 million.

Nevertheless, uptake appears to be increasing. Vertex reported Casgevy sales of $116 million in 2025, with 64 patients receiving infusions during the year. In the first quarter of 2026, the company recorded $43 million in sales and stated that more than 500 patients had initiated treatment since the therapy’s launch.

The latest FDA decision marks another milestone for CRISPR-based medicines and could significantly expand access to a treatment that offers the possibility of long-term disease control for children living with two severe inherited blood disorders.