OR17-4 Transcon Growth Hormone In The Treatment Of Pediatric Growth Hormone Deficiency: Results Of The Phase 3 Height Trial

Abstract

TransCon Growth Hormone in the Treatment of Pediatric Growth Hormone Deficiency: Results of the Phase 3 heiGHt Trial Background TransCon Growth Hormone is a sustained-release recombinant human growth hormone (hGH; somatropin) prodrug in development as a long-acting GH (LAGH) for children with growth hormone deficiency (GHD). In its prodrug form, TransCon hGH is inactive with hGH transiently bound to a TransCon carrier via a TransCon linker. Upon injection and triggered by physiological pH and temperature, unmodified recombinant hGH is sustainably released and thus designed to maintain the same mode-of-action and distribution as daily hGH replacement therapy but with once-weekly dosing. In a 6-month phase 2 trial of TransCon hGH vs. a daily hGH in children with GHD, mean annualized height velocity (AHV) for TransCon hGH was 12.9 cm/y compared to 11.6 cm/y for a daily hGH at an equivalent hGH dose (0.21 mg/kg/wk). The subsequent pivotal phase 3 global heiGHt Trial (ClinicalTrials.gov: NCT02781727) was designed to investigate the safety, tolerability, and efficacy of weekly TransCon hGH versus daily hGH over 52 weeks in treatment-naive prepubertal children with GHD. Methods Subjects were randomized in a 2:1 ratio and received either once-weekly TransCon hGH 0.24 mg hGH/kg/wk or dose-equivalent once-daily Genotropin over 52 weeks. Key baseline demographics variables included age, gender, height standard deviation score (SDS), IGF-1 SDS, peak stimulated GH, and bone age delay. Study endpoints included AHV, IGF-1 response, immunogenicity, and safety. Results At baseline, the mean age of study participants, of whom 82% were male, was 8.5 years. Mean height SDS was -2.93, and mean IGF-1 SDS was -2.04. Mean peak stimulated GH was 5.77 µg/L, and mean bone delay was 2.63 years. The final sample size (n=161) was larger than planned (n=150) which strengthens the study power for noninferiority. Top-line results, including AHV, change in height SDS, serum IGF-1 levels, change in bone age, and adverse events, will be available for presentation at ENDO 2019. Conclusion Only LAGHs based on unmodified hGH have obtained approval in Europe or the United States. By February 2019, all subjects will have completed their participation in this pivotal trial of a LAGH designed to release unmodified hGH, with top-line analyses available in March. The heiGHt Trial was well-powered to demonstrate noninferiority between TransCon hGH and a daily hGH, with baseline demographic variables in the range of recent GH trials.