Early Neonatal Administration of Vosoritide in Achondroplasia: A Report of Two Cases.
Early administration of vosoritide in infants with achondroplasia was tolerated, but it did not prevent complications like foramen magnum stenosis.
Where it sits
this study against the rest of the vosoritide corpusSummary and findings
Two infants with genetically confirmed achondroplasia received daily subcutaneous vosoritide starting on postnatal days 8 and 9. Both patients tolerated treatment without serious adverse events, but progressive foramen magnum stenosis was observed. Both required decompression surgery at 9 and 5 months of age, respectively.
Abstract
Vosoritide, a C-type natriuretic peptide analogue that inhibits FGFR3 signaling, is approved for the treatment of achondroplasia (ACH) from birth in Japan, Australia, and the United States; however, data on neonatal use remain limited. We report two infants with genetically confirmed ACH who received daily subcutaneous vosoritide starting on postnatal days 8 and 9, representing the earliest initiation reported to date. Both patients tolerated treatment in the short term without serious adverse events during inpatient or outpatient monitoring. Despite early initiation, serial magnetic resonance imaging demonstrated progressive foramen magnum stenosis during infancy, and both patients required decompression surgery at 9 and 5 months of age, respectively, consistent with the known natural history of ACH, with an uncomplicated postoperative course in both cases. Growth trajectories, assessed by growth velocity (GV), were generally above the ACH-specific reference medians at comparable ages, while the characteristic slowing of GV during infancy was preserved. These observations are descriptive and hypothesis-generating only and do not support changes in current clinical practice. Further data are required to clarify the potential benefits and limitations of initiating vosoritide therapy during the neonatal period.
Background
This paper addresses the use of vosoritide, a C-type natriuretic peptide analogue, in the treatment of achondroplasia, particularly focusing on its early neonatal administration. Prior knowledge indicates that vosoritide is approved for use from birth in certain countries, but data on its neonatal application are limited. This study is significant as it reports the earliest initiation of treatment in infants with genetically confirmed achondroplasia.
Methods
The study reports on two infants with achondroplasia who received daily subcutaneous vosoritide starting on postnatal days 8 and 9. The monitoring included inpatient and outpatient follow-up for adverse events. Primary outcomes included the assessment of growth trajectories and the occurrence of foramen magnum stenosis.
Results
Both patients tolerated the treatment without serious adverse events. Serial magnetic resonance imaging showed progressive foramen magnum stenosis, leading to decompression surgery at 9 and 5 months of age. Growth velocity was generally above the achondroplasia-specific reference medians, although the characteristic slowing of growth velocity during infancy was preserved.
Interpretation
The findings suggest that while early administration of vosoritide is tolerated, it does not prevent known complications such as foramen magnum stenosis, which aligns with the natural history of achondroplasia. The small sample size limits the ability to generalize these results, and the effect size regarding growth velocity, while statistically significant, may not be clinically meaningful. The implications for practice remain uncertain without further data.
Key findings
- Both patients tolerated treatment without serious adverse events during inpatient or outpatient monitoring.
- Progressive foramen magnum stenosis was demonstrated by serial magnetic resonance imaging.
- Both patients required decompression surgery at 9 and 5 months of age, respectively.
- Growth trajectories were generally above the achondroplasia-specific reference medians at comparable ages.
- The characteristic slowing of growth velocity during infancy was preserved.
Limitations
- Only two case reports, small n=2.
- Descriptive and hypothesis-generating observations.
- No long-term follow-up data reported.
- No statistical analysis of growth velocity provided.