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Dr. Ravi Savarirayan and his team published a paper in the New England Journal of Medicine with results from Biomarin's Vosoritide phase 2 dose-finding and extension study for children with achondroplasia aged 5-14 years, showing a sustained increase in annualized growth velocity.


This study enrolled a total of 35 children who were divided into 4 cohorts receiving different doses of the drug (2.5, 7.5, 15 and 30 μg per kilogram of body weight). After 6 months the 2.5 μg group's dose was increased to 7.5 μg and the 7.5 μg group was increased to 15 μg and the treatment continued for up to 42 months. Annualized growth velocity was observed to increase by up to 2.34 cm/year compared to the baseline measurements taken in the last 6 months of the observation study they were previously enrolled in. Although in cohorts 3 and 4, who were continuously given 15 and 30μg of vosoritide per kg of body weight respectively, the highest increase in annualized growth velocity was observed, there wasn't a significant difference between these two doses. [1] Change in this parameter from baseline for cohort 3 was 1.46cm/year in the last 12 months of the study, meaning that these children were growing 1.46cm/year more than when they started the study.

Cohort 1 (2.5 μg/kg)
(N = 8)
Age range 5–10 yo
Cohort 2 (7.5 μg/kg)
(N = 8)
Age range 5–10 yo
Cohort 3 (15.0 μg/kg)
(N = 10)
Age range 6–11 yo
Cohort 4 (30.0 μg/kg)
(N = 9)
Age range 5–8 yo


The height difference between the children in the study and the average height population also decreased by about 15 to 20%. [2]  The growth between the upper (trunk) and lower-body (legs) segments remained stable, what is translated in a no change in upper-to-lower body ratio, keeping the existent disproportionality.


During the treatment periods in the dose-findingDuring the treatment periods in the dose-finding and extension studies, adverse events occurred in 35 of 35 patients (100%) [1]. As reported before, there were injection-site reactions and blood pressure drops, although these were mild and transient and didn't represent a serious risk to the patient. Also, some serious adverse events were observed, such as obstructive sleep apnea, tonsillar hypertrophy, thyroglossal cyst (a cyst in the neck) and a syrinx (a collection of cerebrospinal fluid forming a pseudocyst). Adverse events are different from adverse effects/reactions, in the sense that adverse events are any health complications that might be observed in a patient during a clinical trial, not necessarily linked to the treatment being administered, and adverse effects are any noxious or unintended effects that can be attributed directly to the treatment being administered in a clinical trial. [3]

No difference in efficacy or safety could be identified between the once-daily doses of 15 and 30 μg per kilogram; thus, the findings support the choice of the lower dose (15 μg) for further evaluation in ongoing studies. A phase 3, randomized, double-blind, placebo-controlled trial is currently evaluating the efficacy and safety of the 15 μg/ kg dose of vosoritide in up to 110 children (age range, 5 to <18 years) with achondroplasia. An open-label phase 3 extension study will further evaluate the efficacy and safety of will vosoritide until patients reach final adult height.[1]

Although there are still other parameters to investigate, such as changes in foramen magnum size, these results show an improvement in growth, with a mild side-effect profile.



  1. Savarirayan, R., Irving, M., Bacino, C. A., Bostwick, B., Charrow, J., Cormier-Daire, V., . . . Hoover-Fong, J. (2019). C-Type Natriuretic Peptide Analogue Therapy in Children with Achondroplasia. New England Journal of Medicine. doi:10.1056/NEJMoa1813446
  2. BioMarin Announces New England Journal of Medicine Publishes Vosoritide Phase 2 Study Showing Sustained Annualized Growth Up to 42 Months in Children with Achondroplasia (2019)
  3. Eurordis Open Academy. (2018). Pharmacovigilance Glossary
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