Novel therapies for growth disorders

As we continue to understand more about the complex mechanism of growth, a plethora of novel therapies have recently been developed that aim to address barriers and optimize efficacy. This review aims to explore these novel therapies and provide a succinct review based on the latest clinical studies in order to introduce clinicians to therapies that will soon constitute the future in the field of short stature.  Conclusion: The review focuses on long-acting growth hormone formulations, a novel growth hormone oral secretagogue, novel treatments for children with achondroplasia, and targeted therapies for rare forms of skeletal dysplasias. What is Known: • Recombinant human growth hormone has been the mainstay of treatment for children with short stature for years. • Such therapy is not always effective based on the underlying diagnosis (e.g achondroplasia, Turner syndrome). Compliance with daily injections is challenging and can directly affect efficacy. What is New: • Recent development of long-acting growth hormone regimens and oral secretagogues can overcome some of these barriers, however several limitations need to be taken into consideration. • Newer therapies for achondroplasia, and other rare forms of skeletal dysplasias introduce us to a new era of targeted therapies for children with short stature. Clinicians ought to be aware of pitfalls and caveats before introducing these novel therapies to every day practice.

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.

Efficacy and Safety of Once-Weekly Somatrogon Compared with Once-Daily Somatropin (Genotropin®) in Japanese Children with Pediatric Growth Hormone Deficiency: Results from a Randomized Phase 3 Study

INTRODUCTION

Somatrogon is a long-acting recombinant human growth hormone being developed as a once-weekly treatment for children with growth hormone deficiency (GHD). The objective of this phase 3 study (NCT03874013) was to compare the efficacy and safety of once-weekly somatrogon with once-daily Genotropin in Japanese children with GHD.

METHODS

In this open-label, randomized, active-controlled study, 44 prepubertal Japanese children with GHD (boys: 3 to <11 years; girls: 3 to <10 years) were randomized 1:1 to receive once-weekly somatrogon or once-daily Genotropin (0.025 mg/kg/day) for 12 months. Dose escalation for somatrogon-treated subjects occurred in the first 6 weeks (0.25, 0.48, and 0.66 mg/kg/week; 2 weeks each) with the remaining 46 weeks at a dose of 0.66 mg/kg/week. The study's primary endpoint was annualized height velocity (HV) at 12 months.

RESULTS

Baseline characteristics were similar between treatment groups. Compared with Genotropin-treated subjects, somatrogon-treated subjects had higher least-squares mean HV at 12 months (9.65 cm/year vs. 7.87 cm/year). Once-weekly somatrogon was concluded as being comparable to once-daily Genotropin as the mean treatment difference (somatrogon-Genotropin) in HV was +1.79 cm/year (95% confidence interval, 0.97-2.61), which was greater than the preestablished margin (-1.8 cm/year). For both treatment groups, most adverse events were mild to moderate in severity and a similar proportion of subjects reported injection-site pain, although the somatrogon group reported more painful injections.

CONCLUSION

In prepubertal Japanese children with GHD, once-weekly somatrogon was comparable to once-daily Genotropin in terms of annualized (12-month) HV. Both treatments had similar safety and tolerability profiles.