Independent biopharmaceutical company Specialised Therapeutics (ST) is pleased to announce the Australian registration of SKYTROFA® (lonapegsomatropin) as a new once-weekly injectable therapy for paediatric growth hormone deficiency (GHD).^[2] The Therapeutic Goods Administration (TGA) has approved SKYTROFA as a treatment for "growth failure in children and adolescents aged from 3 years up to 18 years due to insufficient endogenous growth hormone secretion".^[1,2]

GHD is a rare disease affecting around 2-3/10,000 Australians, with approximately 2,000 children thought to be living with the condition.^[3] It occurs when the pituitary gland, located at the base of the brain, does not produce an adequate level of growth hormone, which is essential for promoting healthy growth in children.^[3] In children, GHD is typically characterised by slow height growth, resulting in short stature, and may also include delayed puberty, impaired hair growth and headaches.^[3] The goal of treatment for GHD is to restore normal levels of growth hormone in the body, reduce physical symptoms, enhance metabolic health and improve quality of life.^[3]

ST Chief Executive Officer, Mr Carlo Montagner, said the TGA approval of SKYTROFA demonstrated the company's ongoing mission to support patients with rare diseases in Australia and the Asia-Pacific region.

"We are delighted to have secured TGA registration of SKYTROFA for eligible Australian children with growth hormone deficiency. Beyond short stature, children and adolescents with the condition may experience considerable physical and psychosocial impacts on their daily life, such as poor concentration, decreased strength or muscle development, fatigue, and reduced quality of life.^[4]

"This announcement also represents a significant milestone for Specialised Therapeutics, marking the second endocrinology therapy we have successfully registered in Australia, following the approval of YORVIPATH^® (palopegteriparatide) earlier this year," said Mr Montagner.

SKYTROFA is being registered in Australia by ST, under an exclusive distribution agreement with biopharmaceutical company Ascendis Pharma A/S that covers Australia, New Zealand, Singapore, Malaysia, Brunei, Thailand, and Vietnam. The Australian registration of SKYTROFA follows approvals issued to Ascendis Pharma by the United States Food and Drug Administration (US FDA)^[5] in August 2021 and the European Medicines Agency (EMA)^[6] in January 2022.

Developed using Ascendis Pharma's proprietary TransCon^TM platform, SKYTROFA is delivered as a subcutaneous injection, available in various strengths.^[2] The starting dose depends on the patient's body weight and is then adjusted individually by the treating endocrinologist based on the patient's response to treatment.^[2]

Ascendis Pharma's innovative TransCon^TM technology platform is designed to create new therapies with the potential to optimise therapeutic effect, including improving treatment efficacy, safety and dosing frequency.^[7] TransCon^TM molecules have three components: an unmodified parent drug, an inert TransCon™ carrier that protects it, and a TransCon^TM linker that temporarily binds the two.^[7]

SKYTROFA is a prodrug of somatropin administered once weekly, designed to provide sustained release of active, unmodified somatropin.^[6] This allows the medicine to slowly release unmodified growth hormone into the body over the course of one week, removing the need for daily injections.

SKYTROFA consists of three components: the parent drug somatropin, an inert methyloxypolyethlene glycol carrier (mPEG), and a proprietary TransCon^TM linker that transiently binds the other two elements.^[8,9] While bound, the carrier inactivates the somatropin and shields it from renal excretion and receptor-mediated clearance.^[10] Following injection, autocleavage of the linker occurs under physiologic conditions, and SKYTROFA releases fully active, unmodified somatropin in a predictable manner.^[10]

The TGA registration of SKYTROFA was based on the results of Ascendis Pharma's three pivotal Phase 3 clinical trials, heiGHt, fliGHt and enliGHten, which collectively treated more than 300 paediatric patients diagnosed with GHD, including from Australia.^[2,8,11,12]

SKYTROFA was generally well-tolerated across all three clinical trials. The most commonly reported adverse events include viral infections, fever, cough, nausea and vomiting, haemorrhage, diarrhoea, abdominal pain, arthralgia, arthritis, and increased blood phosphate levels.

PBS Information: SKYTROFA is not listed on the Pharmaceutical Benefits Scheme (PBS).