MON-227 - Real-World Growth Outcomes Following Vosoritide Therapy in Kazakhstani Children with Achondroplasia.

Background.
Disproportionate short stature in children with achondroplasia, caused by a pathogenic variant in the FGFR3 gene, has become treatable with vosoritide following its approval in 2021. However, real-world data on its effectiveness and safety remain limited. Here, we present the findings from a single-centre experience in Kazakhstan regarding the use of vosoritide in 39 children with this condition.
Methods.
Children aged >5 years with genetically confirmed achondroplasia were included. Clinical data were retrospectively collected from routine medical records. Ten children began vosoritide in March 2023; one patient died in an accident unrelated to treatment and was excluded, 30 began vosoritide in December 2024. All received vosoritide as daily subcutaneous injections at 15 mcg/kg. Height standard deviation scores (Ht SDS) were calculated using achondroplasia reference data (ACH) and general population data.
Results
Thirty-nine children with achondroplasia (age 7.5 ± 2.8 years, range 2.7–13.2 years), including 10 females and 29 males, were included at baseline. Height increased from 96 cm (range 70–125) at baseline to 102 cm (75–132) after the first year of treatment and to 115.5 cm (101–135) among those who completed two years of therapy (n=9). Annual growth velocity improved to 5.9 ± 1.58 cm/year (range 1.5–9) during the first treatment year and remained elevated at 5.05 ± 1.37 cm/year (range 3–7) in the second year. Mean achondroplasia height SDS increased from −0.25 (range −2.6 to 1.82) at baseline to 0.24 (−2.25 to 2.12) after one year and 0.89 (−0.41 to 2.03) after two years of treatment. Height SDS relative to the general population improved from −4.7 (−6.5 to −3.0) at baseline to −4.4 (−6.3 to −2.5) at one year and −4.1 (−5.6 to −3.0) at two years. There was no increase in sleep apnea after one year; no cases were reported after two years of therapy.

Conclusion:
Vosoritide therapy resulted in improved linear growth in children with achondroplasia over 2.5 years, consistent with findings from clinical trials and other real-world studies. While most patients responded well, some showed limited height gain, warranting further investigation into factors such as adherence and individual variability. Our experience supports the feasibility and effectiveness of vosoritide use in a real-world clinical setting. Continued follow-up is needed to assess long-term outcomes and optimize treatment strategies.

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