Insulin-like growth factor-1 (IGF-1) is a key hormone in mediating the physiological response to endogenous and exogenous growth hormone (GH). Current clinical guidelines suggest use of IGF-1 for dose titration in adults with GH deficiency and for safety monitoring in adults and pediatric patients. Several GH drug development programs for pediatric indications have collected IGF-1, height standard deviation score (HSDS), and height velocity (HV), to support dose selection in Phase 3 clinical trials. In this analysis, patients born small for gestational age (SGA) who fail to demonstrate catch-up growth by age 2–4 years from different growth hormone product development programs were included. A total of 663 patients from 8 clinical trials were included in this analysis, with 7 placebo arms and 15 growth hormone treated arms. The growth hormone dosing regimen ranged from 33 ug/kg/day to 100 ug/kg/day. Both boys and girls throughout a wide range of ages (3 to 7 years old on average) were represented in this analysis. The average patient was 3 to 4 standard deviations below the age- and sex- adjusted mean height at baseline. IGF-1 was collected and standardized according to age and sex, so called the IGF-1 standard deviation score (IGF-1 SDS). At baseline, the average patient had normal IGF-1 (-1 to 0 on average). Based on preliminary findings, IGF-1 SDS change from baseline (CFB) at 6 months was correlated with HSDS CFB at 12 months. HSDS CFB at 3 months and 6 months were also correlated with HSDS CFB at 12 months, respectively. These findings were consistent across the three GH products included in the analysis, as well as age and gender. However, IGF-1 SDS CFB had much larger variability than HSDS CFB. Both HSDS CFB at 3 months and 6 months precisely and accurately predicted HSDS CFB at 12 months. IGF-1 SDS was more variable and did not add any further contribution in the prediction of HSDS at 12 months and therefore IGF-1 may not be sufficient in informing Phase 3 dose selection in such trials.
Reference: 1. Shoshana Yakar, Clifford J. Rosen, Wesley G. Beamer, et al. Circulating levels of IGF-1 directly regulate bone growth and density. J Clin Invest. 2002 Sep 15; 110(6): 771–781. 2. Locatelli V, Bianchi VE. Effect of GH/IGF-1 on Bone Metabolism and Osteoporosis. Int J Endocrinol. 2014;2014:235060 Nothing to Disclose: TL, JP, BC, MZ, JV, CS