Somatrogon (Ngenla) – Weekly Growth Hormone Therapy: An update from Peter Laing – Advanced Nurse Practitioner, Endocrinology, Alder Hey Children’s Hospital
Background
Treatment with daily GH injections has been a mainstay in the management of GHD for close to 40 years.
Since 2022, the options for management have changed in that there is now the availability of a Long-Acting Growth Hormone (LAGH) formulation that is given once weekly.
Somatrogon is recommended, within its marketing authorisation, as an option for treating growth disturbance that is caused by growth hormone deficiency in children and young people aged 3 years and over.
Following recent marketing authorisation by NICE – www.nice.org.uk/guidance/ta863 – clinicians can consider Somatrogon from one of a range of suitable treatments that are available (including any preparation of somatropin) and discuss the advantages and disadvantages of GH products/devices with parents, carers, children and young people.
The decrease in frequency of injection provided by LAGH has the potential to improve adherence and has the potential for better patient engagement and concordance with treatment, potentially maximise efficacy related to improved treatment outcomes and offer increase flexibility for children and young people.
Evidence from clinical trials has demonstrated that Ngenla (LAGH) is as effective as one preparation of somatropin (Genotropin) with non-inferior annual height velocity achieved.
Weekly administration of LAGH was generally well tolerated in paediatric patients with GHD and the most commonly reported treatment related adverse event was injection site reactions.
Injection site reactions included an increase in injection site pain and erythema.
About Somatrogon (Ngenla)
Ngenla is available in a pen-device with two strengths of formula available – 24mg pen and 60mg pen. The device is pre-loaded with the GH medicine and premixed and is disposable following use.
The 24mg pen can administer doses in increments of 0.2mg that range from 0.2mg to a maximum dose of 12mg per dose actuation.
The 60mg pen can administer doses in increments of 0.5mg that range from 0.5mg to a maximum dose of 30mg per dose actuation.
Both formulations contain 1.2mls of solution per pen device. The recommended dose is 0.66 mg/kg body weight administered once weekly by subcutaneous injection.
Each pre-filled pen is capable of setting and delivering the dose prescribed by the clinician. The dose may be rounded up or down based on the clinician’s expert knowledge of the individual patient needs.
When doses higher than 30 mg are needed (i.e. bodyweight > 45 kg), two injections have to be administered on the same day.
Ngenla dose may be adjusted as necessary, based on growth velocity, adverse reactions, body weight and serum insulin-like growth factor 1 (IGF-1) concentrations, which should be checked 4 days after the prior dose of Ngenla.
Both the 24mg and 60mg Ngenla device use a standard 5mm needle for administration (4mm-8mm needles can be used with 31-32G) and the pen devices do not have a needle cover/guard.
Ngenla is stored in a refrigerator between 2 and 8 degrees and can be taken out of the fridge before use and held at room temperature for up to 4 hours. The pen can be used for up to 28 days after the first use (first injection) before it needs to be discarded.
The weekly dose of Ngenla can be changed if needed and it is recommended that there are at least 3 days since the last dose. Ngenla can therefore be given up to 3 days past the normal dosing day.
Alder Hey experience of Somatrogon (Ngenla)
Since autumn 2022 we have been prescribing Ngenla for some patients with a diagnosis of GHD. The decision to prescribe Ngenla has been based on clinical diagnosis and within the licensed indication > 3years.
Key factors have included both the eligibility of patients who may be considered for a LAGH formulation and following a discussion concerning choice and the preference of the child, young person and their family.
Selecting the most appropriate pen size is important to ensure adequate weekly dosing and to minimize potential wastage of medicine where possible. The recommended dose is 0.66mg/kg body weight and to ensure adequate dosing the dose is rounded up when needed. For patients with a body weight >45kg patients are counselled that they will need two injections given on the same day once weekly as the maximum dose actuation with the 60mg pen is 30mg per injection.
The use of the pen is relatively simple. Training and education of children, young people and their families usually takes a similar amount of time as to the standard daily GH formulations.
Needle covers/guards are not available, for some patients switching from a daily GH formulation this has been a feature that they have on occasion noticed and provided comment.
The volume of medicine per injection is more than with the standard daily GH formulations. This can result in a slightly longer period of injection following administration.
Some patients have complained of minor discomfort but not significantly more than with the standard daily GH formulation.
We have also been arranging for patients to have a blood sample collected for IGF-1 measurement approximately 6 weeks following initiation of treatment, 4 days following their last injection of Ngenla.
Overall, patients have reacted positively to this new GH formulation, reduced burden associated with frequency of injection has been welcome.
In terms of response to treatment we do not have any patients that have been on Ngenla longer than 6 months and we will continue to evaluate the efficacy and safety at approximately 6 to 12 month intervals and assessed by evaluating auxological parameters, biochemistry (IGF-1, hormones, glucose levels) and pubertal status.
