RF26 | PMON334 Once-Weekly Somapacitan in Growth Hormone Deficiency: 4-Year Efficacy and Safety Results from REAL 3, a Randomised Controlled Phase 2 Trial
Authors: Savendahl Lars , Battelino Tadej , Rasmussen Michael Højby , Saenger Paul , Horikawa Reiko 
Published: November 2022

The current treatment for growth hormone deficiency (GHD) requires daily subcutaneous injections, which can be burdensome. Somapacitan is a long-acting growth hormone (GH) derivative in development for once-weekly use in children with GHD.

REAL 3 (NCT02616562) is an ongoing, phase 2, multinational, randomised, open-label, controlled trial designed to investigate the efficacy and safety of somapacitan compared with daily GH (Norditropin®). Prepubertal children with GHD who were naïve to GH treatment received 0.04 (n=16), 0.08 (n=15) or 0.16 mg/kg/week (n=14) somapacitan, or daily GH 0.034 mg/kg/day (equivalent to 0.238 mg/kg/week; n=14) for 1 year. This was followed by a 2-year safety extension, in which all patients on somapacitan (n=45) received 0.16 mg/kg/week, while patients receiving daily GH remained on daily GH. In a further, ongoing 4-year long-term safety extension, patients treated with somapacitan remained on somapacitan (somapacitan/somapacitan, n=39) and all patients on daily GH switched to somapacitan 0.16 mg/kg/week (daily GH/somapacitan, n=11). Here, we present efficacy and safety results from the first year of the 4-year long-term safety extension.

At year 4, the mean (SD) height velocity (HV) was 7.4 (1.6) cm/year for the somapacitan/somapacitan group and 6.6 (1.6) cm/year for the daily GH/somapacitan group, compared with 8.3 (1.7) and 7.6 (2.0) cm/year for the somapacitan/somapacitan and daily GH groups, respectively, at year 3. The mean (SD) HV standard deviation score (SDS) was 1.55 (1.70) for the somapacitan/somapacitan group and 0.88 (1.61) for the daily GH/somapacitan group, and the mean (SD) change in height SDS from baseline was 2.85 (1.25) and 2.28 (0.97), respectively. The mean (SD) insulin-like growth factor-I SDS at year 4 was 1.29 (1.23) and 0.94 (1.60) for the somapacitan/somapacitan and daily GH/somapacitan groups, respectively.

During year 4, 20 patients (51.3%) experienced 84 adverse events (AEs) in the somapacitan/somapacitan group, and eight patients (72.7%) experienced 12 AEs in the daily GH/somapacitan group. The most common AE was nasopharyngitis, occurring in four patients (10.3%) in the somapacitan/somapacitan group and one patient (9.1%) in the daily GH/somapacitan group; all other AEs occurred in &lt;10% of patients in either group. Most AEs were mild or moderate and unlikely related to GH treatment. One severe AE (surgery for elbow fracture) occurred in the somapacitan/somapacitan group. No serious AEs were reported in year 4. Since previously reported in year 3, one patient in the somapacitan/somapacitan group experienced five injection-site reactions; none occurred in the daily GH/somapacitan group.

In conclusion, these year 4 data support the efficacy and safety results of somapacitan observed in the previous 3 years of the trial. In year 4, height-related outcomes were similar for patients who continued treatment with somapacitan and those who switched from daily GH to somapacitan. Somapacitan was well tolerated, and no safety signals were identified.

Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m., Monday, June 13, 2022 12:44 p.m. - 12:49 p.m.