Real-World Safety and Effectiveness of Vosoritide in Children with Achondroplasia: French Early Access Program

Abstract

Introduction: Vosoritide is the first approved treatment for achondroplasia, a rare genetic disorder that results in disproportionate short stature. In clinical trials, vosoritide has shown a positive safety profile and increased height in children with achondroplasia. This article shares the organizational structure, initiation, follow-up protocol, and findings of a vosoritide early access program (EAP) conducted in France.

Methods: Participants aged ≥5 years with achondroplasia and open epiphyses were eligible for enrollment in the EAP, conducted by six centers within the French national rare disease reference center for constitutional bone diseases network, from 24 June 2021 to 13 December 2022. Treatment consisted of once-daily subcutaneous vosoritide 15 μg/kg. Safety and effectiveness (height, height Z-score, annualized growth velocity [AGV]) data over a 12-month follow-up period were collected.

Results: Among 62 enrolled participants, 57 started treatment with vosoritide within the EAP period with 38 completing at least 6 months and 22 at least 12 months of treatment. After 12 months of treatment, participants achieved a mean AGV of 6.0 cm/year, absolute gain in height of 6.2 cm, and increase in height Z-score referenced to the average stature population of 0.38. All adverse events were mild (mainly injection site reactions) and there were no discontinuations related to vosoritide treatment.

Conclusions: In this first use of vosoritide in a real-world setting, vosoritide had a positive benefit-risk ratio similar to that observed in vosoritide clinical trials. The French EAP provides a model that may be adapted and adopted for use in other countries.

Keywords: Achondroplasia; Early access program; Growth; Safety; Vosoritide.