Investigating the Bioavailability and Insulin-like Growth Factor-I Release of Two Different Strengths of Somapacitan: A Randomised, Double-Blind Crossover Trial.

ABSTRACT

STUDY DESIGN AND OBJECTIVE: Randomised, double-blind, crossover trial to confirm bioequivalence of somapacitan, a long-acting growth hormone (GH), in 5 mg/1.5 mL and 10 mg/1.5 mL strengths in equimolar doses. METHODS: Healthy participants were randomised (111) to subcutaneous somapacitan treatment in one dosing period with 5 mg/1.5 mL and two periods with 10 mg/1.5 mL. Eligibility criteria included age 18-45 years and body mass index 18.5-24.9 kg/m2. Exclusion criteria included history of GH deficiency, previous GH treatment, weight > 100.0 kg and participation in any clinical trial of an investigational medicinal product within 45 days or five times the half-life of the previous investigational product before screening. Area under the curve from time 0 until last quantifiable observation (AUC0-t), maximum serum concentration (Cmax), time to Cmax and terminal half-life of somapacitan and safety were assessed. RESULTS: In total, 33 participants were randomised. For AUC0-t, estimated treatment ratio (ETR) (5 mg/1.5 mL versus 10 mg/1.5 mL) was 0.95 (90% confidence interval [CI] 0.89-1.01). Point estimate and 90% CIs were within the acceptance range (0.80-1.25). For Cmax, ETR was 0.77 (90% CI 0.68-0.89). Point estimate and 90% CIs were outside the acceptance range (0.80-1.25). Mean insulin-like growth factor-I (IGF-I) and IGF-I standard deviation score concentration-time curves for each strength were almost identical. No new safety issues were identified. CONCLUSIONS: Bioequivalence criterion for somapacitan 5 mg/1.5 mL and 10 mg/1.5 mL was met for AUC0-t but not for Cmax. The two strengths had equivalent IGF-I responses. TRIAL REGISTRATION ClinicalTrials.gov, NCT03905850 (3 April 2019).

Somapacitan is a long-acting growth hormone used to treat people with growth hormone deficiency. Somapacitan is injected under the skin with an injection pen. The dose is based on a person's body weight and how they respond to treatment. We compared two strengths of injection pen, containing either 5 or 10 mg of somapacitan per 1.5 mL. For both strengths, participants were given the same dose. We wanted to understand whether the body absorbs these different strengths into the bloodstream in the same way. We also measured levels of insulin-like growth factor-I (IGF-I), a hormone formed when growth hormone is present in the blood, to see the effect of different strengths of somapacitan on the body. In our study, 33 healthy adults received one round of injection using the somapacitan 5 mg pen and two rounds using the somapacitan 10 mg pen, all at least 3 weeks apart. We found no differences in the amount of somapacitan being absorbed into the bloodstream, nor how fast it was absorbed. The peak amount of somapacitan in the bloodstream was higher in people using the 10 mg pen. There were no differences in IGF-I levels following use of either injection pen. Overall, our results show both strengths of somapacitan lead to similar responses in the body. Having different strength options could allow doctors to adjust the dose of somapacitan more easily, depending on a patient's response to treatment.