PROLOR conducted a Phase I study of hGH-CTP and released the results on February 2, 2010. The Phase I study enrolled 24 healthy adults who were randomized to receive one of three doses of hGH-CTP (4mg, 7mg, or 21mg) or placebo. The study results showed that safety and tolerability endpoints were met at all doses in all participants. The potential clinical efficacy of hGH-CTP was assessed by measuring the extent to which hGH-CTP induced insulin-like growth factor-1 (IGF-1) in subjects. This biomarker is the clinically accepted primary indicator of hGH biological activity and is used by endocrinologists to optimize dosing for hGH-deficient adults. Based on this measure, the study results suggest that the daily injections required by patients using conventional hGH could potentially be replaced with just two monthly injections of hGH-CTP.