General Information

Skytrofa (lonapegsomatropin-tcgd) is a pegylated human growth hormone (somatropin).

Skytrofa is specifically indicated for the treatment of pediatric patients 1 year and older who weigh at least 11.5 kg and have growth failure due to inadequate secretion of endogenous growth hormone (GH).

Skytrofa is supplied as a solution for subcutaneous injection. The recommended dose of Skytrofa for treatment-naïve patients and patients switching from daily somatropin therapy is 0.24 mg/kg body weight, given once-weekly.

Individualize and titrate the dosage of Skytrofa based on response.

When changing from daily somatropin therapy to once-weekly Skytrofa, wait at least 8 hours between the final dose of daily somatropin and the first dose of once-weekly Skytrofa.

Assess compliance and evaluate other causes of poor growth such as hypothyroidism, undernutrition, advanced bone age and antibodies to recombinant human growth hormone if patients experience failure to increase height velocity, particularly during the first year of treatment.

Discontinue Skytrofa once epiphyseal fusion has occurred.

Missed Doses

Administer a missed dose as soon as possible and not more than 2 days after the missed dose.

To avoid missed doses, Skytrofa can be taken 2 days before or 2 days after the scheduled dosing day. Resume once-weekly dosing for the next dose at the previously scheduled dosing day.

If more than 2 days have passed from the scheduled day, skip the dose and administer the next dose on the regularly scheduled day.

At least 5 days should elapse between doses.

Mechanism of Action

Skytrofa (lonapegsomatropin-tcgd) is a pegylated human growth hormone (somatropin). Somatropin binds to the growth hormone (GH) receptor in the cell membrane of target cells resulting in intracellular signal transduction and a host of pharmacodynamic effects. Somatropin has direct tissue and metabolic effects, and indirect effects mediated by insulin-like growth factor-1 (IGF-1), including stimulation of chondrocyte differentiation and proliferation, stimulation of hepatic glucose output, protein synthesis and lipolysis. Somatropin stimulates skeletal growth in pediatric patients with growth hormone deficiency (GHD) as a result of effects on the growth plates (epiphyses) of long bones.

Clinical Trial Results

The FDA approval of Skytrofa was based on results from the phase 3 heiGHt Trial, a 52-week, global, randomized, open-label, active-controlled, parallel-group trial that compared once-weekly Skytrofa to daily somatropin (Genotropin) in 161 treatment-naïve children with GHD. The primary endpoint was Annualized Height Velocity (AHV) at 52 weeks for weekly Skytrofa compared to somatropin. At week 52, the treatment difference in AHV was 0.9 cm/year (11.2 cm/year for Skytrofa compared with 10.3 cm/year for daily somatropin). The primary objective of non-inferiority in AHV was met for Skytrofa in this trial and further demonstrated a higher AHV at week 52 for lonapegsomatropin compared to daily somatropin, with similar safety, in treatment-naïve children with GHD.