Vertex Pharmaceuticals has presented the first clinical data for Casgevy in children ages 5-11 at the American Society of Hematology annual meeting, on December 6, 2025, in Orlando. All evaluated children in the sickle cell cohort remained free of vaso-occlusive crises for up to two years after the one-time therapy, per company disclosures reported by Sickle Cell Disease News.
What did the pediatric studies show?
The presentation covered the first-ever clinical data for Casgevy (exagamglogene autotemcel) in children ages 5-11, spanning severe sickle cell disease and transfusion-dependent beta thalassemia. In the CLIMB-151 sickle cell study, all children with sufficient follow-up met the goal of being free of vaso-occlusive crises for at least one year, per the report. Safety was described as consistent with prior studies in adults and adolescents, and fetal hemoglobin increases were observed.
| Study | Population | Reported result |
|---|---|---|
| CLIMB-151 | Children 5-11, severe SCD with recurrent crises | All children free of VOCs for up to two years; four with sufficient follow-up VOC-free at least one year, per company data reported by Sickle Cell Disease News |
| CLIMB-141 | Children 5-11, TDT | 13 patients dosed; all six with sufficient follow-up achieved transfusion independence, per company disclosure reported by Big Molecule Watch |
Lead author Haydar Frangoul was quoted by Sickle Cell Disease News saying that a 100% success rate is rare in anything that we do. These are company-presented results from early-cohort pediatric patients; the studies continue to enroll and follow participants.
How does Casgevy work as a therapy?
Casgevy is a non-viral, ex-vivo CRISPR/Cas9 gene-edited cell therapy, as described in regulatory commentary by Big Molecule Watch: a patient's own blood stem cells are collected, edited at the BCL11A gene to induce fetal hemoglobin production, then reinfused after conditioning chemotherapy. The one-time regimen is why pediatric data matter, since intervening before cumulative organ damage is the clinical rationale for treating younger patients. In the US, Casgevy is currently approved for sickle cell disease and transfusion-dependent beta thalassemia in patients 12 years and older; use in ages 5-11 remains investigational.
What happens next for the label?
Vertex stated that it expects to initiate global regulatory filings for the 5-11 age group in the first half of 2026, including a supplemental Biologics License Application in the United States. The company has also received a Commissioner's National Priority Voucher from the FDA for accelerated review of the sBLA once submitted, per the same analysis.
The pediatric expansion is a commercial and access question as much as a scientific one. Casgevy revenue reached the company's stated goal of more than $100 million in 2025, reflecting more than 60 patient infusions, per a January 2026 Vertex update cited in the roundup coverage. A broader label would widen the eligible population, while cell collection and infusion capacity remain the practical constraints on volume. The CLIMB-151 report and the ASH presentation are the primary sources for the pediatric figures; longer follow-up has not yet been published in a journal.
This article is provided for informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional regarding any treatment or diagnostic decision.
