Treatment Burden of Weekly Somatrogon vs Daily Somatropin in Children With Growth Hormone Deficiency: A Randomized Study

Long-acting growth hormone in the management of GHD in France

Approximately 10,000 children in France with growth hormone deficiency (GHD) are being administered daily recombinant human growth hormone (rhGH). Although this treatment has long proved efficient for restoring children's growth and metabolism, daily injections of rhGH have a few limitations, such as difficulties in terms of adherence to treatment, which may compromise growth during childhood but also metabolism in adulthood. In addition to the disease burden and besides the adherence hurdles, the obligations related to daily injection have a negative impact on the quality of life of patients and their families. The hypothesis that injections administered at intervals of 1 week, or even 1 month, could improve compliance, reduce treatment discontinuations, and optimize quality of life and therapeutic effectiveness has led to the emergence of new long-acting growth hormone (LAGH). Recent access to LAGHs (somatrogon MA) on the European and French market will likely be followed by a high demand from the families concerned and may raise questions on their effectiveness, safety, and practical use. Numerous practical and practice-related points are needed to guide prescribing physicians while many concerns are still left unresolved (treatment effectiveness or ineffectiveness endpoints, long-term effectiveness, etc.). These issues can only be addressed in the future by compiling registries and conducting long-term real-world studies.

Post hoc subgroup analysis of Asian children with paediatric GHD from the global phase 3 efficacy and safety study of once-weekly somatrogon vs. once-daily somatropin

OBJECTIVES

Somatrogon is a long-acting recombinant human growth hormone used to treat patients with paediatric growth hormone deficiency (pGHD). This global phase 3 study compared the efficacy and safety of once-weekly somatrogon with once-daily somatropin in children with GHD.

METHODS

Prepubertal patients were randomized 1:1 to once-weekly somatrogon (0.66 mg/kg/week) or once-daily somatropin (0.24 mg/kg/week) for 12 months. The primary endpoint was height velocity (HV) at month 12; secondary endpoints included HV at month 6 and change in height standard deviation score (SDS) at months 6 and 12 and insulin-like growth factor 1 (IGF-1) SDS.

RESULTS

This post hoc subgroup analysis focused specifically on Asian children (somatrogon: n=24 and mean age=7.76 years; somatropin: n=21 and mean age=8.10 years) across eight countries. Mean HV at month 12 was 10.95 cm/year (somatrogon) and 9.58 cm/year (somatropin); the treatment difference of 1.38 cm/year favoured somatrogon. The lower bound of the two-sided 95 % CI of the treatment difference (somatrogon-somatropin) was -0.20, similar to the overall study population (-0.24). Compared with the somatropin group, the somatrogon group had numerically higher HV at month 6 (8.31 vs. 11.23 cm/year); a similar trend was observed for height SDS and IGF-1 SDS at months 6 and 12. Safety and tolerability were similar between treatment groups; adverse events occurred in 83 % of somatrogon-treated children and 76 % of somatropin-treated children.

CONCLUSIONS

This subgroup analysis demonstrated that somatrogon efficacy and safety in Asian children were consistent with the overall study population, where once-weekly somatrogon was non-inferior to once-daily somatropin. Clinicaltrials.gov: NCT02968004.

Developments in the Management of Growth Hormone Deficiency: Clinical Utility of Somapacitan

Growth hormone (GH) replacement therapy for growth hormone deficiency (GHD) in children and adults has for over 25 years, until recently, been administered as daily injections. This daily treatment regimen often incurs a burden to patients and caregivers, leading to high rates of non-adherence and, consequently, decreased treatment efficacy outcomes. To address this shortcoming, long-acting growth hormones (LAGHs) have been developed with the aim of reducing the burden of daily injections, thereby potentially improving treatment adherence and outcomes. Somapacitan (Sogroya®) (Novo Nordisk, Bagsværd, Denmark) is a LAGH currently approved for the treatment of adult and childhood GHD (AGHD and CGHD, respectively) in several countries. Other LAGHs, such as somatrogon (Ngenla®) (Pfizer, New York, United States) and lonapegsomatropin/TransCon GH (Skytrofa®) (Ascendis Pharma, Copenhagen, Denmark), are also currently approved and available for the treatment of CGHD in several countries. In this review, we will consider the method of protraction, pharmacokinetics (PK) and pharmacodynamics (PD), efficacy, and safety results of somapacitan in adult and pediatric trials and how these characteristics differ from those of the other aforementioned LAGHs. Additionally, the administration of somapacitan and timing of measurement of serum insulin-like growth factor-I (IGF-I) levels are summarized. Information on administration, advice on missed doses, and clinical guidelines are discussed, as well as identifying which patients are suitable for somapacitan therapy, and how to monitor and adjust dosing whilst on therapy.

Health-related quality of life in pre-pubertal children with pediatric growth hormone deficiency: 12-month results from a phase 3 clinical trial of once-weekly somatrogon versus once-daily somatropin

OBJECTIVE

Treatment of pediatric growth hormone deficiency (pGHD) with daily injection of recombinant human growth hormone (somatropin) aims to increase height velocity and improve health-related quality of life (HRQoL). The Quality of Life in Short Stature Youth (QoLISSY) questionnaire was administered in a phase 3 clinical trial that evaluated efficacy and safety of once-weekly somatrogon versus once-daily somatropin in children with pGHD (ClinicalTrials.gov no NCT02968004).

METHODS

Treatment-naïve prepubertal children with pGHD received once-weekly somatrogon or once-daily somatropin for 12 months. The QoLISSY core module (physical/social/emotional subscales) was administered at baseline and 12 months after treatment initiation. QoLISSY-Parent was completed by parents/caregivers of children <7 years old and some parents/caregivers of children ≥7 years old; children ≥7 years old self-completed QoLISSY-Child.

RESULTS

Baseline characteristics were similar between treatment groups (N = 117). Among children <7 years old, QoLISSY-Parent total and subscale scores showed similarly improved HRQoL at 12 months relative to baseline in both treatment groups. Self-reported QoLISSY-Child total and subscale scores in children ≥7 years old indicated HRQoL improvements at 12 months that were numerically better with somatrogon than somatropin (similar results with QoLISSY-Parent in this age group). At both time points, children reported better HRQoL than perceived by their parents/caregivers.

CONCLUSION

Treatment for 12 months with once-weekly somatrogon or once-daily somatropin resulted in comparable improvements in HRQoL among children with pGHD. Lower HRQoL perceived by parents/caregivers possibly reflect children's tendency to emphasize adaptation. These results suggest that evaluation of HRQoL could help support treatment decisions in children with pGHD treated with growth hormone.

Somatrogon injection for the treatment of pediatric growth hormone deficiency with comparison to other LAGH products

INTRODUCTION

Somatrogon (NGENLA™) is a long-acting GH (LAGH) formulation that was approved in Canada in October 2021 for the treatment of pediatric growth hormone deficiency (GHD). Somatrogon has also received approval in Australia, Japan, the European Union, the USA, and the UK. Somatrogon is a glycoprotein that utilizes three copies of the C-terminal peptide of human chorionic gonadotropin to delay its clearance allowing for once-weekly administration.

AREAS COVERED

The purpose of this article is to describe the development of somatrogon for treatment of individuals with GHD. Trials of somatrogon demonstrated positive efficacy results in adults (Phase 2) and children (Phase 2 and 3) with GHD including non-inferiority of height velocity compared to daily GH, with no concerning side effects. Growth responses, pharmacodynamics and safety data are compared to other LAGH products, lonapegsomatropin and somapacitan, in Phase 3 trials in pediatric GHD.

EXPERT OPINION

New LAGH products, including somatrogon, have the potential to increase patient adherence as well as improve quality of life and clinical outcomes. Clinicians will need to identify the best candidates for LAGH therapy and understand how to safely monitor and adjust therapy. Long-term surveillance studies are necessary to demonstrate adherence, efficacy, cost-effectiveness, and safety of LAGH preparations.

Physician experience with once-weekly somatrogon versus once-daily rhGH regimen in pediatric patients with growth hormone deficiency: a cross-sectional survey of physicians from the global phase 3 study

Introduction

The standard of care for pediatric growth hormone deficiency (pGHD) is once-daily recombinant human growth hormone (rhGH). Somatrogon, a long-acting rhGH, requires less frequent, once-weekly, dosing. We describe physicians' preference for, experiences, and satisfaction with once-weekly somatrogon vs once-daily rhGH.

Methods

English-speaking investigators from somatrogon's global phase III study (NCT02968004) with prior experience using once-daily rhGH were included. Participants answered an online survey containing 14 closed- and open-ended items.

Results

Twenty-four pediatric endocrinologists (41.7% men; 79.2% practiced at public/private hospitals) from 12 countries with 25.8 ± 12.0 years' experience treating pGHD completed the survey. In terms of the time and effort required to explain device instructions, injection regimen, procedure for missed injection, and address patients'/caregivers' concerns, a similar proportion of physicians chose once-weekly somatrogon and once-daily rhGH; 62.5% physicians indicated that once-daily rhGH required greater effort to monitor adherence. Overall, 75% preferred once-weekly somatrogon over once-daily rhGH, 79.2% considered once-weekly somatrogon to be more convenient and less burdensome, and 83.3% were likely to prescribe somatrogon in the future. Overall, 50% felt that once-weekly somatrogon was more beneficial to patients, while 50% chose "No difference". Most physicians (62.5%) felt both regimens were equally likely to support positive long-term growth outcomes and reduce healthcare utilization. More physicians were "very satisfied" with once-weekly somatrogon (62.5%) than with once-daily rhGH (16.7%). Reduced injection frequency, patient and caregiver burden, increased convenience, and improved adherence were reasons for these choices.

Conclusion

Physicians had a positive experience with, and perception of, treating pGHD with once-weekly somatrogon.

Long acting growth hormone (LAGH), an update

In 1957, Maurice Raben at Yale was able to isolate and purify growth hormone from cadaveric pituitary glands. Pituitary growth hormone was the only way to treat children with growth hormone (GH) deficiency, until 1985 when recombinant GH became available for daily subcutaneous injection. For many years, the pediatric endocrine community longed for a long-acting recombinant GH formulation that would decrease the inconvenience of daily injections. Several mechanisms were employed to develop a GH that is rapidly absorbed into the blood stream after subcutaneous injection, but provides slow removal from the circulatory system to potentially optimize patient adherence to GH therapy. Four long-acting growth hormones are currently available in the world, or are close to regulatory approval. They are: (1) Pegylated formulations, (2) Prodrug formulations which are converted into active drug, (3) Nonvalent transient albumin binding GH compounds and (4) GH fusion proteins where a protein si fused with GH. All four formulations have undergone detailed phase 3 studies and were found to show non-inferiority in these clinical studies. All four demonstrate a safety and tolerability profile that is comparable to that of daily somatropin with an excellent adherence profile.

Cost-effectiveness of somatrogon in the Spanish pediatric population with growth hormone deficiency

OBJECTIVE

To analyze the cost-effectiveness of weekly somatrogon compared to daily growth hormones (GH-d) in the pediatric population of Spain with growth hormone deficiency (GHD).

METHODS

Markov model with two states (patients with or without GH-d or somatrogon treatment) in prepubertal children (3 to 11 years and 3 to 12 years in girls and boys, respectively) with GHD in isolation or as part of multiple pituitary hormone deficiency and without previous treatment, from the perspective of the National Health System. The simulation of the economic model ends at the age of 18. The costs of hormones and monitoring were obtained from Spanish sources. The utilities were obtained from the literature. Spanish clinical experts validated the assumptions of the model.

RESULTS

In the deterministic analysis, somatrogon would be cost-effective, compared to GH-d, with a cost per QALY (quality-adjusted life year) gained of €19,259 and a clinically relevant QALY gain (0.336). This result was confirmed in deterministic sensitivity analyses. According to the probabilistic analysis, somatrogon would be the dominant treatment, with a 61% probability of a willingness to pay of €25,000 per QALY gained.

CONCLUSION

Compared to GH-d, somatrogon is cost-effective in the Spanish pediatric population with GHD.

Treatment burden, adherence, and quality of life in children with daily GH treatment in France

OBJECTIVE

The objective of this study was to describe in a real-life setting the treatment burden and adherence and quality of life (QOL) of children treated with daily injections of growth hormone and their relationship with treatment duration.

DESIGN

This non-interventional, multicenter, cross-sectional French study involved children aged 3-17 years treated with daily growth hormone injections.

METHODS

Based on a recent validated dyad questionnaire, the mean overall life interference total score (100 = most interference) was described, with treatment adherence and QOL, using the Quality of Life of Short Stature Youth questionnaire (100 = best). All analyses were performed according to treatment duration prior to inclusion.

RESULTS

Among the 275/277 analyzed children, 166 (60.4%) had only growth hormone deficiency (GHD). In the GHD group, the mean age was 11.7 ± 3.2 years; median treatment duration was 3.3 years (interquartile range 1.8-6.4). The mean overall life interference total score was 27.7 ± 20.7 (95% CI (24.2; 31.2)), with non-significant correlation with treatment duration (P = 0.1925). Treatment adherence was good (95.0% of children reported receiving >80% of planned injections over the last month); it slightly decreased with treatment duration (P = 0.0364). Children's overall QOL was good (81.5 ± 16.6 and 77.6 ± 18.7 according to children and parents, respectively), but subscores of the coping and treatment impact domains were <50. Similar results were observed in all patients independently of the condition requiring treatment.

CONCLUSIONS

This real-life French cohort confirms the treatment burden of daily growth hormone injections, as previously reported in an interventional study.

Cost-effectiveness and cost-utility analysis of somatrogon once-weekly injections vs. daily growth hormone injection for treating paediatric growth hormone deficiency in Ireland

OBJECTIVES

Paediatric growth hormone deficiency (pGHD) manifests as growth failure associated with inadequate growth hormone (GH) production. Daily injections of recombinant human GH (dGH) [somatropin] is the current standard of care, which has been shown to be well tolerated and effective, but associated with suboptimal adherence, leading to reduced effectiveness. Somatrogon, a once-weekly injectable long-acting human GH, has demonstrated clinical non-inferiority and significantly lower life interference (i.e. treatment burden) vs. somatropin in two Phase 3 studies. This work evaluated cost-effectiveness and cost-utility of somatrogon vs dGHs from an Irish payer perspective.

METHODS

A Markov model was developed for patients starting somatrogon or dGHs treatment at 3-12 years and continuing up to achievement of near adult height (NAH), with growth driven by trial-based height velocity (HV) and treatment-specific adherence. Patients could discontinue treatment at the end of Year 1 (4%). DGH adherence (95.3%-65% over treatment duration) and adherence-growth relationship were based on published evidence. Higher Year 1 adherence of 4%, tapering over time, for somatrogon vs. dGHs was based on clinical consultation. Treatment costs, monitoring costs and costs due to different wastage types (device setting and adherence) were sourced from local data. Health utilities based on height and injection frequency were derived from published literature. Scenario analysis, deterministic and probabilistic sensitivity analysis were performed.

RESULTS

Somatrogon treatment led to 1.87-3.66 cm greater NAH gain and 0.21-0.50 higher quality adjusted life years (QALYs) vs. dGHs, across the base case and scenarios evaluated. Somatrogon treatment was associated with cost savings of €5,699-€21,974 and lower cost per cm gained vs. dGHs (€197-€527), per patient. Somatrogon was cost-effective vs. dGHs, with the result consistent across the sensitivity analyses conducted.

CONCLUSION

Somatrogon weekly injections were estimated to result in higher NAH, higher QALYs, lower overall costs and lower costs per cm gained than dGHs, in pGHD.

Persistence with daily growth hormone among children and adolescents with growth hormone deficiency in the UK

BACKGROUND

Children with growth hormone deficiency (GHD) are treated with daily somatropin injections; however, poor treatment persistence and adherence have been recognized previously and have been shown to negatively impact growth outcomes. A recent real-world study of a US pediatric GHD population found that a substantial proportion of children discontinued somatropin therapy, but similar data for a real-world UK population are lacking.

OBJECTIVES

To describe the discontinuation of, and persistence with, daily somatropin treatment among children with GHD in the UK.

METHODS

This was a retrospective cohort study of children (≥3 and <16 years old) with ≥1 medication prescription for daily injectable somatropin from 1 July 2000 to 31 December 2020 in the IQVIA Medical Research DATA (IMRD) database. Early persistence was defined as the proportion of children prescribed ≥1 somatropin refill (≥2 prescriptions). Discontinuation was defined as the first date at which a medication gap for somatropin (of >60 or >90 days between prescriptions) occurred. Kaplan-Meier methods were used to evaluate persistence (non-discontinuation) over time to assess time to first discontinuation event. Cox proportional hazards models were used to evaluate the relationship between patient characteristics and time to medication discontinuation.

RESULTS

Among the cohort identified in this study (n = 117), the majority (n = 84, 71.8%) had 48 months of available follow-up; 56.4% were boys and the mean (median) age was 8.6 (8.0) years. About 98% exhibited early persistence, but persistence over the follow-up period decreased with follow-up duration. Using the conservative 90-day gap definition of persistence, an estimated 72.4%, 52.8%, and 43.3% were persistent at 12, 36, and 48 months. Lower persistence rates were observed using the 60-day definition. No significant patient predictors of time to discontinuation were identified.

CONCLUSIONS

Despite high early persistence with somatropin, a high percentage of children with GHD were increasingly non-persistent over time. More than 1 in 4 were non-persistent at 12 months and more than 1 in 2 were non-persistent at 48 months of follow-up. These results suggest that strategies to support improved medication-taking behavior among children with GHD in the UK are warranted.