Vertex Presents First-Ever CASGEVY Data in Children Ages 5-11

Abstract

At the 2025 American Society of Hematology (ASH) Annual Meeting (December 2025), Vertex Pharmaceuticals presented data demonstrating the clinical benefits of CASGEVY (exagamglogene autotemcel, exa-cel) in patients ages 5 years and older with severe sickle cell disease (SCD) or transfusion-dependent beta thalassemia (TDT). This is the first-ever clinical data in children 5-11 years. Vertex plans to initiate global regulatory submissions for the pediatric population in 1H 2026.

Key Contributions

• First pediatric CASGEVY clinical data (ages 5-11) — extends the first CRISPR-approved gene therapy to younger patients.
• 1H 2026 global regulatory submissions planned for pediatric expansion.
• Continued clinical maturation of CASGEVY across age groups (originally approved for ≥12 years).
• Commercial validation of ex vivo CRISPR gene editing as a marketable therapy.

Methodology / Trial Design

• Pediatric cohort enrolled in ongoing clinical trials supporting age-extension submissions.
• Primary endpoints: safety, vaso-occlusive crisis (VOC) reduction in SCD, transfusion independence in TDT.
• ASH 2025 presentation summarized data through cutoff date.

Results

• Pediatric (ages 5-11) safety profile consistent with adult/adolescent data.
• Clinical benefit (VOC reduction, transfusion independence) demonstrated in pediatric cohort.
• Specific numerical results in Vertex ASH 2025 presentation.

Limitations

• Pediatric cohort sizes are smaller than adult/adolescent pivotal trials.
• Long-term follow-up in pediatric patients (>5 years) accumulates over time.
• Treatment requires conditioning chemotherapy and stem cell transplant — significant procedure burden.

Full Content

CASGEVY's expansion to pediatric populations is commercially significant. Sickle cell disease + transfusion-dependent beta thalassemia together affect ~70,000-100,000 US patients with severe disease, with onset of symptoms typically in early childhood. Treating earlier prevents the cumulative organ damage that accrues over years of chronic disease.

The 1H 2026 regulatory submissions span the US (FDA), EU (EMA), UK (MHRA), and other jurisdictions where CASGEVY is already approved for ≥12 years. Successful pediatric expansion broadens the addressable market and earlier intervention windows.

This connects to the broader 2026 gene therapy commercial wave:

• Casgevy (Vertex/CRISPR Therapeutics): ex vivo CRISPR — sickle cell + beta thalassemia, expanding to pediatric.
• Lyfgenia (Bluebird Bio): ex vivo lentiviral gene therapy — sickle cell.
• Beam Therapeutics: in vivo base editing — alpha-1 antitrypsin deficiency, sickle cell next.
• Verve Therapeutics: in vivo CRISPR — cholesterol (Cleveland Clinic trial).
• Krystal Biotech / others: AAV-based gene therapies.
• In vivo prime editing: cardiac (RBM20 humanized mouse model, Feb 2026 bioRxiv).

The trajectory: 2024-2025 was about getting the first ex vivo CRISPR therapy approved and reimbursed. 2026-2027 is about: (a) extending Casgevy to younger and broader populations, (b) bringing in vivo gene editing therapies into late-stage trials, (c) reducing the procedure burden (eliminate conditioning chemo, simplify delivery).

Source: Vertex Newsroom — Vertex Presents New Data on CASGEVY, Including First-Ever Data in Children Ages 5-11 Years, at ASH Annual Meeting, December 2025