Real-world effectiveness of vosoritide in children with achondroplasia: Results from 18 months follow-up in France

Valerie Cormier-Daire; Thomas Edouard; Bertrand Isidor; Jeanne Pimenta; Swati Mukherjee; Valeria Marcos; Anne Dee; Massimiliano Rossi; Elise Schaefer; Sabine Sigaudy; Geneviève Baujat

P2-56

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ESPE Abstracts (2024) 98 P2-56

ESPE2024 Poster Category 2 Bone, Growth Plate and Mineral Metabolism (31 abstracts)

Real-world effectiveness of vosoritide in children with achondroplasia: Results from 18 months follow-up in France

Valerie Cormier-Daire ¹ , Thomas Edouard ² , Bertrand Isidor ³ , Jeanne Pimenta ⁴ , Swati Mukherjee ⁴ , Valeria Marcos ⁵ , Anne Dee ⁶ , Massimiliano Rossi ⁷ , Elise Schaefer ⁸ , Sabine Sigaudy ⁹ & Geneviève Baujat ¹

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¹Hôpital Necker Enfants Malades, Paris, France. ²Toulouse University Hospital, Toulouse, France. ³Hospitalier Universitaire de Nantes, Nantes, France. ⁴BIOMARIN, London, United Kingdom. ⁵Biomarin, Paris, France. ⁶Biomarin, Novato, USA. ⁷Hospices Civils de Lyon, Lyon, France. ⁸Hôpital de Hautepierre, Strasbourg, France. ⁹Hôpital Timone Enfant, Marseille, France

Introduction: Achondroplasia is the most common skeletal dysplasia, caused by a pathogenic FGFR3 variant, leading to impaired endochondral bone growth and multiple medical complications. Vosoritide, a modified recombinant human C-type natriuretic peptide (rhCNP), was first approved by the European Medicines Agency in August 2021 and is now approved for treating genetically-confirmed achondroplasia in patients aged ≥4 months until closure of epiphyses. Health Authorities granted early access (EA) to vosoritide treatment in France and treatment was started in September 2021, prior to commercialization on 13 December 2022. Effectiveness and safety results of the EA population were previously reported (including a subset of patients who reached 12 months of treatment); here, we present an additional follow-up to 18 months.

Methods: Within the EA program, vosoritide was initiated in ACH patients aged ≥5 years with open epiphyses. Patients/families received treatment education and were followed-up at months 1, 3, 6 and every 6 months thereafter where data on treatment compliance and effectiveness parameters (mean [standard deviation, SD] height, Z-score using Centers for Disease Control and Prevention [CDC] reference population and ACH Z-score using Hoover-Fong 2021) were collected. Annualized growth velocity (AGV) was also calculated.

Results: A total of 62 patients were enrolled, of which 57 (52% males) started vosoritide within the EA program; mean (min–max) age at treatment initiation was 8.6 (5–13) years. At June 2023, 16 patients (4 males;12 females) completed ≥18±1 months of treatment (mean [SD] exposure of 18.34 [1.06] months). Effectiveness parameters are in Table 1.

Table 1: Change in height-related measurements after ≥18±1 months vosoritide treatment.
Mean (SD)	Overall n = 16	Males n = 4	Females n = 12
Age at treatment initiation, years	9.52 (1.48)	8.84 (1.49)	9.75 (1.47)
Height increase from baseline, cm	8.84 (1.53)	7.50 (1.37)	9.28 (1.34)
CDC Z-score improvement from baseline	0.43 (0.57)	0.38 (0.34)	0.45 (0.63)
ACH Z-score improvement from baseline	0.56 (0.28)	0.30 (0.30)	0.64 (0.23)
AGV^a, cm/year	5.76 (1.07)	4.94 (0.93)	6.03 (1.0)
^aAGV is defined as (change in height between baseline and final visit) / (time between visits)*365.25 There were no known discontinuations during the 18 months of treatment.

Conclusion: These data from 16 children with achondroplasia indicate that vosoritide treatment in real-world conditions shows continued effectiveness after ~18 months, with results consistent with vosoritide clinical trials and other real-world treatment studies. Long term effectiveness and safety data collection for these patients will continue through the European Post-Authorisation Safety Study.