- In children with X-linked hypophosphatemia, burosumab led to improved renal phosphate reabsorption, growth, serum phosphorus levels, and function, along with reduced disease severity and less pain.
Why this matters
- This recombinant monoclonal antibody has already shown similar effects in trials in adults.
- These results are from a pediatric efficacy and safety trial of the drug.
- Improvements seen with burosumab include:
- Thacher rickets severity score, baseline to week 40: decreased from 1.9 to 0.8 (dosing every 2 weeks); from 1.7 baseline to 1.1 (dosing every 4 weeks; P<.001 both>
- Mean serum phosphorus: increased after the first dose, in normal range by week 6 in more than half of patients (both dose groups); stable levels maintained to week 64, dosing every 2 weeks.
- Increased renal phosphate reabsorption and height z-scores.
- Improved pain/comfort and function scores in both dose groups.
- No clinically significant safety findings.
- Open-label, phase 2 trial.
- 52 children: 26 dosing every 2 weeks, 26 dosing every 4 weeks.
- Dose adjusted to serum phosphorus level.
- Primary endpoint: change, baseline to 40, 64 weeks.
- Funding: Ultragenyx Pharmaceutical, Kyowa Hakko Kirin.
- No active control group; trial comparing drug to conventional therapy is ongoing.