European regulators have backed earlier use of two orphan therapies for rare pediatric diseases that affect muscle and bone development, lowering treatment age thresholds for both medicines.

At its April 2026 meeting, the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) adopted positive opinions to expand the use of Agamree and Crysvita. The recommendations reflect a broader push toward earlier intervention in rare genetic conditions, where delayed treatment can have long-term functional consequences.

Earlier Intervention for Duchenne Muscular Dystrophy 

The CHMP recommended a label expansion for Agamree (vamorolone, Santhera Pharmaceuticals), now indicated for the treatment of Duchenne muscular dystrophy in patients aged 2 years or older. This lowers the previous age threshold of 4 years, allowing earlier intervention in this progressive muscle-wasting disease.

Agamree contains vamorolone, which is a first-in-class dissociative corticosteroid. It is designed to retain the anti-inflammatory efficacy of traditional glucocorticoids while potentially reducing systemic side effects, specifically stunting of growth and bone demineralization by altering the way it interacts with glucocorticoid receptors. 

Clinical evidence supporting vamorolone in Duchenne muscular dystrophy includes a 24-week trial of 133 boys in which vamorolone 6 mg/kg per day significantly improved time-to-stand velocity compared with placebo (P = .002). Vamorolone-treated patients also maintained normal growth trajectories, and bone turnover markers did not show the marked declines typically associated with chronic steroid use. The CHMP did not identify a specific trial supporting the age expansion to patients aged 2 years or older.

The most common side effects with Agamree include cushingoid features, vomiting, increased weight, and irritability.

The medicine is available as an oral suspension, with the dose determined by the patient’s body weight. However, this medicine is under additional monitoring. 

Expanded Use in Phosphate-Wasting Disorders 

Crysvita (burosumab, Kyowa Kirin) received a positive opinion to extend its use to infants as young as 1 month for the treatment of X-linked hypophosphatemia (XLH) with laboratory evidence of the condition. 

Crysvita is already indicated for fibroblast growth factor 23 (FGF23)-related hypophosphatemia in children and adolescents (aged 1-17 years) with radiographic evidence of bone disease, and in adults, as well as for tumor-induced osteomalacia associated with phosphaturic mesenchymal tumors that cannot be resected.

XLH and tumor-induced osteomalacia are characterized by excess FGF23, which causes renal phosphate wasting, leading to rickets in children and osteomalacia in adults. Burosumab is a monoclonal antibody that binds to and inhibits FGF23, restoring phosphate homeostasis.

Clinical evidence in pediatric XLH has shown that burosumab improves radiographic signs of rickets and phosphate homeostasis in children, although the CHMP did not identify a specific trial supporting the extension to infants from 1 month to 1 year of age.

The most common adverse events in pediatric populations include injection site reactions, headache, and vitamin D deficiency.

The medicine can only be obtained with a prescription, and treatment should be started by a doctor experienced in the management of patients with bone diseases caused by alterations in the body’s chemical processes.

Crysvita is administered as a subcutaneous injection every 2 or 4 weeks, with dosing adjusted based on age, weight, and serum phosphate levels.

Both Agamree and Crysvita were originally designated as orphan medicines, and their expanded indications reflect a growing emphasis on earlier therapeutic intervention in rare pediatric diseases.

Detailed recommendations for these new age groups and indications will be available in the updated Summary of Product Characteristics following final marketing authorization by the European Commission.