Skytrofa Approved as Once-Weekly Growth Hormone Deficiency Therapy

The approval was based on data from the phase 3 heiGHt trial that assessed Skytrofa in 161 treatment-naïve, prepubertal patients with growth hormone deficiency.

The Food and Drug Administration has approved Skytrofa® (lonapegsomatropin-tcgd) to treat patients 1 year of age and older weighing at least 11.5kg and have a growth failure due to inadequate secretion of endogenous growth hormone.

Skytrofa is a long-acting prodrug of the human growth hormone, somatropin, produced by recombinant DNA technology using E. coli. The approval was based on data from the multicenter, randomized, open-label, active-controlled, parallel-group phase 3 heiGHt trial ( Identifier: NCT02781727), which assessed the efficacy and safety of Skytrofa in 161 treatment-naïve, prepubertal patients with growth hormone deficiency. 

Patients were randomly assigned 2:1 to receive lonapegsomatropin-tcgd (n=105) administered subcutaneously once weekly or somatropin (n=56) administered subcutaneously daily. The primary endpoint was annualized height velocity at week 52.

Findings showed that treatment with lonapegsomatropin-tcgd met the noninferiority criteria for the primary endpoint resulting in an annualized height velocity of 11.2cm/year at week 52 compared with 10.3cm/year for those treated with somatropin (treatment difference, 0.9; 95% CI, 0.2-1.5). The change from baseline in height standard deviation score was 1.1 in the lonapegsomatropin-tcgd arm and 0.96 in the somatropin arm.

The most common adverse reactions reported were viral infection, pyrexia, cough, nausea/vomiting, hemorrhage, diarrhea, abdominal pain, and arthralgia and arthritis.

Skytrofa is supplied as a single-dose, dual-chamber, prefilled cartridge containing lonapegsomatropin-tcgd and diluent for subcutaneous injection in the following strengths: 3mg, 3.6mg, 4.3mg, 5.2mg, 6.3mg, 7.6mg, 9.1mg, 11mg and 13.3mg. The cartridges are for use only with the Skytrofa Auto-Injector, which is packaged separately.

The Company will also offer patient support programs to assist eligible patients.


  1. Ascendis Pharma A/S announces US Food and Drug Administration approval of Skytrofa® (lonapegsomatropin-tcgd), the first once-weekly treatment for pediatric growth hormone deficiency. News release. Ascendis Pharma. Accessed August 25, 2021.
  2. Skytrofa [package insert]. Palo Alto, CA: Ascendis Pharma, Inc.; 2021.