THU174 Model-Based Analysis Of IGF-I Response, Dosing, And Monitoring For Once-Weekly Somapacitan In Children With GH Deficiency
Authors: Kildemoes Rasmus Juul , Lyauk Yassine Kamal , Blair Joanne C , Miller Bradley S , Mori Jun , Rasmussen Michael Højby , Backeljauw Philippe F 
Published: October 2023

Abstract
Disclosure: R.J. Kildemoes: Employee; Self; Novo Nordisk. Stock Owner; Self; Novo Nordisk. Y. Kamal Lyauk: Employee; Self; Novo Nordisk. J.C. Blair: Speaker; Self; Novo Nordisk, Pfizer, Inc., Ipsen. Other; Self; Novo Nordisk. B.S. Miller: Consulting Fee; Self; Novo Nordisk, Abbvie, Endo Pharmaceuticals, Ascendis Pharma, Bristol-Myers Squibb, Pfizer, Inc., EMD Serono, BioMarin Pharmaceutical, Tolmar. Research Investigator; Self; Alexion Pharmaceuticals, Inc., Abbvie, Aeterna Zentaris, Amicus, Lumos Pharma, Novo Nordisk, Lysogene, OPKO Health, Pfizer, Inc., Prevail Therapeutics, Sangamo Therapeutics. J. Mori: None. M. Højby Rasmussen: Employee; Self; Novo Nordisk. Stock Owner; Self; Novo Nordisk. P.F. Backeljauw: Consulting Fee; Self; Novo Nordisk, Novartis Pharmaceuticals, Ascendis Pharma, BioMarin Pharmaceutical, Tolmar Pharmaceuticals, Cavalry Biosciences, Ipsen. Research Investigator; Self; Novo Nordisk, Novartis Pharmaceuticals, Ipsen.
Growth hormone (GH) replacement therapy improves overall health and adult height in children with GH deficiency (GHD). GH stimulates insulin-like growth factor-I (IGF-I) release, the biomarker commonly used for guiding GH dose adjustments to ensure optimal long-term safety and efficacy. This study aims to provide model-based insights into the dose-IGF-I responses of once-weekly somapacitan, a novel long-acting GH, compared to daily GH in pediatric patients with GHD. Pharmacokinetic/pharmacodynamic (PK/PD) modeling was used to characterize somapacitan dose-IGF-I response and to predict the response to change of dosing day and missed dosing of somapacitan. Analyses included dosing information and 1473 PK samples from 210 GHD patients treated with somapacitan across three trials: phase 1 (NCT01973244), phase 2 (NCT02616562; REAL3), and phase 3 (NCT03811535; REAL4), as well as 1381 IGF-I samples from 186 GHD patients treated with somapacitan from REAL3 and REAL4. A clear dose-response relationship was observed with increasing somapacitan exposure and increasing change from baseline IGF-I SDS. A linear model permitted the development of a tool to calculate the estimated average weekly IGF-I exposure from a single IGF-I sample obtained at any time within the somapacitan dosing interval at steady state. In practice, the use of this tool will require knowledge of the timing of the somapacitan injection relative to the timing of the IGF-I sample collection. IGF-I SDS simulations support flexible dosing day changes while maintaining a minimum of 4 days between doses. In this study, we present a practical guide that may inform clinicians about the expected weekly average IGF-I concentration in somapacitan-treated pediatric patients with GHD from a single sample taken on any chosen day during the weekly dosing interval. The ability to determine weekly average IGF-I enhances our understanding of somapacitan dosing and should support physicians in monitoring long-term safety and efficacy of this therapy. Furthermore, we provide insights on flexibility to change of dosing day and missed dosing of somapacitan.
Presentation: Thursday, June 15, 2023