ESPE Abstracts

Introduction: Vosoritide, a C-type natriuretic peptide analog, has emerged as the first therapeutic agent approved to enhance growth velocity in individuals with achondroplasia (ACH).

Aim: To assess growth response to vosoritide in children with ACH under the care of a specialized multidisciplinary team (MDT).

Methods: A retrospective study was conducted in our center on children diagnosed with ACH who received treatment with once-daily subcutaneous vosoritide. Children enrolled in the study underwent MDT visits every three months, during which QoL assessment, monitoring of medical complications, anthropometric measurements, and adverse event surveillance were conducted. All collected data were analyzed, and standard deviation scores were calculated according to Turkish growth standards.

Results: The cohort in our outpatient clinic comprised of 73 individuals (36 girls). The mean age at presentation was 2.9±3.5 years, ranging from the newborn period to 15.1 years (median 1.6 years). Off-label use permission was sought from the Ministry of Health for 44 patients [median age was 3.6 years (IQR 2.0-6.8, 2 months – 12.2 years]. Treatment initiation was granted for 35 patients [median age at onset of 5.2 years (IQR 2.7-8.0)]. 14% were aged under 2 years, 34% between 2-5 years, 29% between 5-8 years, and 23% between 8-12 years. Twenty-seven patients were prepubertal. The first vosoritide dose was on September 27th, 2022. As of May 2024, the median treatment duration is 8.1 months. Among patients who completed the 6 months (n = 18), the initial and 6^th-month height SDS were -5.05±0.83 and -4.97±0.86, respectively (P = 0.028). For those who completed the first year (n = 7), initial and 1^st-year height SDS were -5.10±1.00 and -4.87±1.00, respectively (P = 0.043). BMI SDS, sitting height/height ratio, and arm span-height difference showed no statistically significant change. Notably, no vosoritide-related adverse events were observed in any of the patients. QoL assessment will also be presented.

Conclusion: We present the early real-world data from the yet largest achondroplasia cohort treated with vosoritide in Turkey. To improve the clinical practice worldwide, it is crucial to present experiences across diverse populations. The growth-promoting effect of vosoritide in children with achondroplasia in the first year was shown also in our cohort, however, its effect on final adult height and other comorbidities persists.