Safety, tolerability, pharmacokinetics, and efficacy of burosumab in infants with X-linked hypophosphataemia: an open-label, multicentre, non-randomised study.

Anti-FGF23 monoclonal antibody (burosumab) normalizing phosphataemia in infants < 12 months

This phase 1/2 study evaluates the safety and efficacy of burosumab in infants under 12 months with pathogenic PHEX variants. Three cohorts (0.4 or 0.8 mg/kg biweekly) show rapid phosphate normalization from week 2, sustained over 48 weeks. Tolerability was comparable to older children. These data support extending the marketing authorization to infants under one year, a population in which early intervention could prevent irreversible skeletal deformities.

Synthesis written by Geno'X. For the full original abstract, please refer to the source publication.

Extending the indication to infants is the key clinical stake of this study: XLH causes skeletal deformities within the first months of life, and conventional phosphate/calcitriol treatment is burdensome and less effective. These results in a high-impact journal should accelerate the regulatory extension — a concrete practice change for geneticists and pediatric endocrinologists managing these families.

Clinical impact: 3/3 · Evidence strength: 2/3 · Novelty: 2/2 · Sample size: 0/1 · Publication status: 1/1 → Total: 8/10