Real-World Vosoritide Treatment Shows Sustained Growth Benefits in Children with Achondroplasia
Key Insights
Real-world studies from Germany and Portugal demonstrate that vosoritide treatment significantly improves growth velocity and height z-scores in children with achondroplasia (search) over 12-24 months.
The German cohort showed mean annualized growth velocity z-scores of 2.13 ± 1.26 compared to disease-specific reference values, while the Portuguese cohort achieved height improvements of +0.95 SD after 24 months.
Treatment was generally well-tolerated with mild injection site reactions being the most common adverse effect, though hypertrichosis (search) emerged as a newly recognized side effect in 14.8% of Portuguese patients.
Two comprehensive real-world studies from Europe provide compelling evidence that vosoritide treatment delivers sustained growth benefits for children with achondroplasia (search), confirming the drug's clinical trial efficacy in routine practice settings.
German Single-Center Experience
A retrospective analysis from University Hospital Cologne (search) examined 34 children with achondroplasia (search) who received vosoritide treatment for at least 12 months between October 2021 and May 2024. The cohort included 12 females and 22 males with a mean age of 7.52 years at treatment initiation.
The study revealed significant improvements in growth parameters. Children demonstrated a mean annualized growth velocity z-score of 2.13 ± 1.26 (P < 0.0001) compared to age-, sex-, and disease-specific reference values. The oldest age group (≥10 to <16 years) showed the highest z-score improvement at 2.30 ± 1.23 (P = 0.0005).
Height z-scores improved substantially across both disease-specific and general population references. The mean achondroplasia (search)-specific height z-score increased from 0.37 ± 1.32 at baseline to 0.89 ± 1.37 after 12 months (P < 0.0001), representing a change of 0.52 ± 0.35. Similarly, CDC z-scores improved from −4.84 ± 1.00 to −4.46 ± 1.06 (P < 0.0001).
Notably, 29 of 32 patients demonstrated improvement in their achondroplasia (search)-specific height z-score, while 26 of 32 showed increases in CDC z-scores. The study also documented significant improvements in 6-minute walking distance z-scores, increasing from −2.00 ± 1.12 to −1.39 ± 1.23 (P = 0.0215).
Portuguese National Cohort Results
The Portuguese study analyzed 27 children with achondroplasia (search) from across the country, representing approximately 85% of diagnosed children in Portugal. This cohort included 12 girls and 15 boys with a mean age of 7.3 years at treatment initiation.
The Portuguese data demonstrated progressive improvements over time. Mean height standard deviation scores increased significantly by +0.38 SD (P ≤ 0.001) after 12 months and +0.95 SD (P ≤ 0.0001) after 24 months when referenced to untreated achondroplasia (search)-specific populations. Compared to general population WHO charts, improvements were +0.21 SD (P ≤ 0.01) at 12 months and +0.56 SD (P ≤ 0.0001) at 24 months.
Annualized growth velocity showed sustained acceleration, increasing from a baseline of 4.25 cm/year to 5.69 cm/year after 12 months and 5.87 cm/year after 24 months (P ≤ 0.0001). This represented a significant increase of +1.62 cm/year compared to baseline after 24 months of treatment.
Body Proportionality Effects
Both studies examined vosoritide's impact on body proportions, a key concern in achondroplasia (search) treatment. The German study found no significant changes in sitting height to height ratio after 12 months, consistent with expectations that proportionality improvements may require longer treatment periods or earlier initiation.
The Portuguese study provided more detailed proportionality data over 24 months. While sitting height to height ratio showed no statistically significant changes overall, the upper to lower segment ratio improved significantly by −0.10 (P ≤ 0.01) in the overall cohort, with boys showing a significant improvement of −0.11 (P ≤ 0.05) at 24 months.
Safety Profile and Tolerability
Both studies confirmed vosoritide's acceptable safety profile in real-world settings. The German cohort reported mild local injection site reactions in 12 of 34 patients (35.3%) and dizziness in two patients as moderate side effects. Importantly, no patients discontinued treatment within the 12-month observation period.
The Portuguese study documented adverse drug reactions in 18 of 27 individuals (66.7%). Injection site reactions were most common, affecting 14 patients (51.9%). A notable finding was hypertrichosis (search) in four patients (14.8%), primarily affecting the dorso-lumbar region. This side effect, not previously identified in clinical trials, has since been added to vosoritide's product labeling as an uncommon adverse reaction.
Treatment adherence was excellent in both studies. The Portuguese cohort reported only 29 missed doses across all patients, equating to 0.71 missing doses per patient per year. No patients discontinued treatment due to adverse drug reactions.
Treatment Response Variability
Both studies identified some patients with limited treatment response. The German study noted three patients who showed slight decreases in achondroplasia (search)-specific height z-scores, though distinguishing characteristics could not be identified. One patient discontinued treatment after 15 months due to lack of therapeutic benefit and treatment burden.
The Portuguese study found that three of four patients who started treatment at age 12 years or older discontinued therapy, primarily due to limited response as they approached skeletal maturity. Additionally, three younger patients showed limited response, including two boys who started treatment at age 2 years.
Clinical Implications
These real-world studies provide crucial validation that vosoritide's clinical trial efficacy translates effectively to routine clinical practice. The German study's mean CDC z-score improvement of 0.38 ± 0.44 actually exceeded the phase 3 trial results of 0.24 ± 0.32 after 52 weeks.
The Portuguese data demonstrated that growth acceleration becomes more apparent over time, with some individuals only showing noticeable effects after 18 months of treatment. The most substantial improvements were observed at 24 months, supporting the need for sustained treatment to achieve optimal outcomes.
Both studies emphasize the importance of specialized care centers with experienced multidisciplinary teams for optimal treatment outcomes. The consistency of measurements and standardized protocols in these single-center studies contributed to the reliability of the findings.
The emergence of hypertrichosis (search) as a newly recognized side effect highlights the value of real-world surveillance in identifying adverse events not captured in clinical trials. However, the fact that treatment continued without interruption in all affected patients suggests this side effect is manageable.
These comprehensive real-world datasets provide healthcare providers and families with confidence that vosoritide's benefits observed in controlled clinical trials are reproducible in routine clinical practice, while maintaining an acceptable safety profile for children with achondroplasia (search).