High-dose GH treatment limited to the prepubertal period in young children with idiopathic short stature does not increase adult height

Effects of different therapy regimens to increase final adult height in males at advanced bone age with idiopathic short stature

BACKGROUND

This retrospective study explored the effect on adult height of a combination of recombinant human growth hormone (rhGH) and aromatase inhibitors (AIs), or rhGH and a gonadotropin-releasing hormone analog (GnRHa), and compared their effects with rhGH alone in males at advanced bone age with idiopathic short stature (ISS).

METHODS

In this retrospective study, rhGH or rhGH combined with GnRHa or rhGH combined with AI therapy was given to males with advanced bone age (13-15 years) and diagnosed with ISS. The patients were followed to assess their adult height.

RESULTS

(1) A total of 68 patients were reviewed; 22 males were treated with rhGH for 24.9 ± 4.47 months, 22 males were treated with GnRHa + rhGH for 34.1 ± 3.36 months, and 24 males were treated with AI + RHGH for 22.7 ± 2.49 months. (2) Before treatment, the HtSDS-CA for the three groups were -1.04 ± 0.95, -1.23 ± 1.06, and -0.85 ± 0.98, respectively, and the HtSDS-BA were -2.14 ± 0.29, -2.14 ± 0.21, and-2.26 ± 0.31, respectively. The target heights for each group were 169.7 ± 4.0 cm, 169.7 ± 3.9 cm, and 169.1 ± 3.9 cm, respectively. The predicted adult heights were 161.7 ± 3.35 cm, 162.3 ± 1.75 cm, and 161.6 ± 2.89 cm, respectively. (3) After treatment, the HtSDS-CA for the rhGH group increased by 1.30 ± 0.58, and the HtSDS-BA increased by 2.00 ± 0.27. For the GnRHa + rhGH group, the HtSDS-CA and HtSDS-BA increased by1.42 ± 0.73and 2.74 ± 0.28, respectively. The AI + RHGH group increased by1.39 ± 0.64 and 2.76 ± 0.31, respectively. (4) There was no significant difference between the adult height (170.9 ± 0.7 cm) and target height for the rhGH group (P > 0.05), but the adult heights for the GnRHa + rhGH and AI + RHGH groups (173.2 ± 1.5 cm and 173.5 ± 1.0 cm, respectively, P > 0.05) were higher than the target height (P < 0.05). (5) Compared with the predicted adult height, the adult heights for the three groups improved significantly (P < 0.05). (6) No severe adverse reactions during the treatment occurred in any of the children. However, the total incidence of side effects in the three groups was significant (χ2 = 20.433, P = 0.00).

CONCLUSION

Different therapeutic approaches have been investigated to improve the final adult height of males at advanced bone ages with ISS, and the optimal strategy remains controversial. In children at advanced bone ages with ISS, clinicians should carefully consider the advantages and disadvantages prior to treatment.

Effect of Growth Hormone Therapy on Pubertal Timing: Systematic Review and Meta-Analysis

INTRODUCTION

Recombinant human growth hormone (rhGH) therapy effectively increases height in various disorders of childhood growth. However, whether rhGH affects pubertal timing is unclear. We aimed to review systematically published evidence on the effect of rhGH on pubertal timing.

METHODS

Embase, MEDLINE, and Cochrane Library databases were searched until December 2021 on randomized and non-randomized controlled studies of rhGH in children.

RESULTS

Twenty-five articles (n = 1,433 children) were identified, describing 12 randomized and 13 non-randomized controlled studies in children with idiopathic short stature (ISS; 15 studies), small for gestational age (n = 6 studies), chronic renal failure (n = 3), Noonan syndrome (n = 1), and growth hormone deficiency (n = 1). Significant differences in the effects of rhGH on pubertal timing were found by clinical indication. Only among children with ISS, rhGH promoted earlier age at pubertal timing (mean difference = -0.46 years; 95% CI, -0.90 to -0.03; 9 studies; n total = 397) or higher relative risk for pubertal onset during study follow-up (1.26; 95% CI, 1.03 to 1.54; 6 studies; n total = 284).

CONCLUSIONS

Treatment with rhGH appears to promote earlier pubertal timing among children with ISS. Evidence was lacking in children with growth hormone deficiency due to the absence of studies with untreated controls.

Plasma exosome miRNA-26b-3p derived from idiopathic short stature impairs longitudinal bone growth via the AKAP2/ERK1/2 axis

BACKGROUND

Currently, the etiology of idiopathic short stature (ISS) is still unclear. The poor understanding of the molecular mechanisms of ISS has largely restricted this strategy towards safe and effective clinical therapies.

METHODS

The plasma exosomes of ISS children were co-cultured with normal human chondrocytes. The differential expression of exosome miRNA between ISS and normal children was identified via high-throughput microRNA sequencing and bioinformatics analysis. Immunohistochemistry, In situ hybridization, RT-qPCR, western blotting, luciferase expression, and gene overexpression and knockdown were performed to reveal the key signaling pathways that exosome miRNA of aberrant expression in ISS children impairs longitudinal bone growth.

RESULTS

Chondrocytes proliferation and endochondral ossification were suppressed after coculture of ISS plasma exosomes with human normal chondrocytes. High-throughput microRNA sequencing and RT-qPCR confirmed that plasma exosome miR-26b-3p was upregulated in ISS children. Meanwhile, exosome miRNA-26b-3p showed a high specificity and sensitivity in discriminating ISS from normal children. The rescue experiment showed that downregulation of miR-26b-3p obviously improved the repression of chondrocyte proliferation and endochondral ossification caused by ISS exosomes. Subsequently, miR-26b-3p overexpression inhibited chondrocyte proliferation and endochondral ossification once again. In situ hybridization confirmed the colocalization of miR-26b-3p with AKAP2 in chondrocytes. In vitro and in vivo assay revealed exosome miRNA-26b-3p impairs longitudinal bone growth via the AKAP2 /ERK1/2 axis.

CONCLUSIONS

This study is the first to confirm that miR-26b-3p overexpression in ISS plasma exosomes leads to disorders in proliferation and endochondral ossification of growth plate cartilage via inhibition of AKAP2/ERK1/2 axis, thereby inducing ISS. This study provides a new research direction for the etiology and pathology of ISS and a new idea for the biological treatment of ISS.

Genetic architecture and heritability of early-life telomere length in a wild passerine

Early-life telomere length (TL) is associated with fitness in a range of organisms. Little is known about the genetic basis of variation in TL in wild animal populations, but to understand the evolutionary and ecological significance of TL it is important to quantify the relative importance of genetic and environmental variation in TL. In this study, we measured TL in 2746 house sparrow nestlings sampled across 20 years and used an animal model to show that there is a small heritable component of early-life TL (h²  = 0.04). Variation in TL among individuals was mainly driven by environmental (annual) variance, but also brood and parental effects. Parent-offspring regressions showed a large maternal inheritance component in TL ( h maternal 2  = 0.44), but no paternal inheritance. We did not find evidence for a negative genetic correlation underlying the observed negative phenotypic correlation between TL and structural body size. Thus, TL may evolve independently of body size and the negative phenotypic correlation is likely to be caused by nongenetic environmental effects. We further used genome-wide association analysis to identify genomic regions associated with TL variation. We identified several putative genes underlying TL variation; these have been inferred to be involved in oxidative stress, cellular growth, skeletal development, cell differentiation and tumorigenesis in other species. Together, our results show that TL has a low heritability and is a polygenic trait strongly affected by environmental conditions in a free-living bird.

Circulating Exosomal circRNA_0063476 Impairs Expression of Markers of Bone Growth Via the miR-518c-3p/DDX6 Axis in ISS

OBJECTIVES

Idiopathic short stature (ISS), a disorder of unknown cause, accounts for approximately 80% of the clinical diagnoses of children with short stature. Exosomal circular RNA in plasma has been implicated in various disease processes. However, the role of exosome-derived circRNA in ISS has not been elucidated yet.

METHODS

Plasma exosomes of ISS and normal children were cocultured with human chondrocytes. Microarray analysis and RT-PCR identified the differential expression of circRNA in exosomes between ISS and normal children. Hsa_circ_0063476 was upregulated or downregulated in human chondrocytes. Subsequently, overexpression rats of hsa_circ_0063476 was constructed via adenoviral vector to further validate the role of hsa_circ_0063476 on longitudinal bone growth via in vivo experiment.

RESULTS

The plasma exosome of ISS children suppressed the expression of markers of chondrocyte hypertrophy and endochondral ossification. Subsequently, upregulation of hsa_circ_0063476 in ISS exosome was identified. In vitro experiments demonstrated that chondrocyte proliferation, cell cycle and endochondral ossification were suppressed, and apoptosis was increased following hsa_circ_0063476 overexpression in human chondrocytes. Conversely, silencing hsa_circ_0063476 in human chondrocytes can show opposite outcomes. Our study further revealed hsa_circ_0063476 overexpression in vitro can enhance chondrocyte apoptosis and inhibit the expression of markers of chondrocyte proliferation and endochondral ossification via miR-518c-3p/DDX6 axis. Additionally, the rats with hsa_circ_0063476 overexpression showed a short stature phenotype.

CONCLUSIONS

The authors identified a novel pathogenesis in ISS that exosome-derived hsa_circ_0063476 retards the expression of markers of endochondral ossification and impairs longitudinal bone growth via miR-518c-3p/DDX6 axis, which may provide a unique therapeutic avenue for ISS.

Circular RNA circANAPC2 mediates the impairment of endochondral ossification by miR-874-3p/SMAD3 signalling pathway in idiopathic short stature

Idiopathic short stature (ISS) is a main reason for low height among children. Its exact aetiology remains unclear. Recent findings have suggested that the aberrant expression of circRNAs in peripheral blood samples is associated with many diseases. However, to date, the role of aberrant circRNA expression in mediating ISS pathogenesis remains largely unknown. The up‐regulated circANAPC2 was identified by circRNA microarray analysis and RT‐qPCR. Overexpression of circANAPC2 inhibited the proliferation of human chondrocytes, and cell cycle was arrested in G1 phase. The expressions of collagen type X, RUNX2, OCN and OPN were significantly down‐regulated following circANAPC2 overexpression. Moreover, Von Kossa staining intensity and alkaline phosphatase activity were also decreased. Luciferase reporter assay results showed that circANAPC2 could be targeted by miR‐874‐3p. CircANAPC2 overexpression in human chondrocytes inhibits the expression of miR‐874‐3p. The co‐localization of circANAPC2 and miR‐874‐3p was confirmed in both human chondrocytes and murine femoral growth plates via in situ hybridization. The rescue experiment demonstrated that the high expression of miR‐874‐3p overexpression antagonized the suppression of endochondral ossification, hypertrophy and chondrocyte growth caused by circANAPC2 overexpression. A high‐throughput screening of mRNA expression and RT‐qPCR verified SMAD3 demonstrated the highest different expressions following overcircANAPC2. Luciferase reporter assay results indicated that miR‐874‐3p could be targeted by Smad3, thus down‐regulating the expression of Smad3. Subsequent rescue experiments of SMAD3 further confirmed that circANAPC2 suppresses endochondral ossification, hypertrophy and chondrocyte growth through miR‐874‐3p/Smad3 axis. The present study provides evidence that circANAPC2 can serve as a promising target for ISS treatment.

The effect of treatment with recombinant human growth hormone (rhGH) on linear growth and adult height in children with idiopathic short stature (ISS): a systematic review and meta-analysis

OBJECTIVES

Idiopathic short stature (ISS) is a recognized, albeit a controversial indication for treatment with recombinant human growth hormone (rhGH).The objective of the present study was to conduct a systematic review of the literature and meta-analyses of selected studies about the use of rhGH in children with ISS on linear growth and adult height (AH).

METHODS

A systematic literature search was conducted to identify relevant studies published till February 28, 2017 in the following databases: Medline (PubMed), Scopus and Cochrane Central Registry of Controlled Trials. After exclusion of duplicate studies, 3,609 studies were initially identified. Of those, 3,497 studies were excluded during the process of assessing the title and/or the abstract. The remaining 112 studies were evaluated further by assessing the full text; 21 of them fulfilled all the criteria in order to be included in the current meta-analysis.

RESULTS

Children who received rhGH had significantly higher height increment at the end of the first year, an effect that persisted in the second year of treatment and achieved significantly higher AH than the control group. The difference between the two groups was equal to 5.3 cm (95% CI: 3.4-7 cm) for male and 4.7 cm (95% CI: 3.1-6.3 cm) for female patients.

CONCLUSION

In children with ISS, treatment with rhGH improves short-term linear growth and increases AH compared with control subjects. However, the final decision should be made on an individual basis, following detailed diagnostic evaluation and careful consideration of both risks and benefits of rhGH administration.

Efficacy and safety of fermented oyster extract for height of children with short stature: a randomized placebo-controlled trial

Background

Some experimental studies have established the effect of oysters on the promotion of body growth. Yet, there is a lack of human clinical studies. The objective of this study was to evaluate the effect of a fermented oyster (FO) extract on the increase in the height of children with stature in the 25th percentile by age.

Methods

In total, 100 children (6–11 years old) were randomly divided into two (FO or control) groups. For 24 weeks, the subjects in the FO group took the FO extract once daily before sleeping, whereas the control group took placebo extracts, simultaneously. We evaluated the height gain, height velocity (HV), height standard deviation score (SDS), urine deoxypyridinoline (DPD), growth hormone (GH), insulin-like growth factor (IGF-1), and IGF binding protein 3 (IGFBP-3).

Results

The height gain and height SDS were significantly higher in the FO group than in the placebo group after 24 weeks (height gain: p < 0.001, height SDS: p < 0.005). The HV was also significantly higher in the FO group than in the placebo group after the 6th and 24th week (p = 0.001, p = 0.004). After 24 weeks, we observed a decrease in GH, IGF, and IGFBP-3 in both groups. However, serum IGFBP-3 level in the FO group reduced less than placebo group.

Conclusion

FO supplementation may help to increase the height of children, and the effect might be mediated via effects on the IGFBP-3 levels.

Hsa_circularRNA_0079201 suppresses chondrocyte proliferation and endochondral ossification by regulating the microRNA‑140‑3p/SMAD2 signaling pathway in idiopathic short stature

Circular (circ)RNAs are an important group of non-coding RNAs involved in different pathological and physiological functions, such as longitudinal bone growth. However, the effects of an increase or decrease in circRNA expression on idiopathic short stature (ISS) remain largely unknown. The present study compared the circRNA expression patterns of patients with ISS and healthy individuals to identify differentially expressed circRNAs involved in the regulation of ISS pathogenesis and their target microRNAs (miR). Microarray analysis revealed that 145 circRNAs were differentially expressed in patients with ISS, including 83 up- and 62 downregulated circRNAs. Reverse transcription-quantitative PCR confirmed that hsa_circRNA_0079201 was increased in patients with ISS compared with that in the normal individuals, whilst hsa_circRNA_0079201 overexpression in human chondrocytes was shown to significantly suppress their proliferation, hypertrophy and endochondral ossification abilities. Luciferase reporter assays identified that circRNA_0079201 acted as an miR-140-3p sponge. In situ hybridization confirmed the co-localization of circRNA_0079201 and miR-140-3p in the human chondrocyte and neonatal femur growth plate of C57 mice, while rescue experiments demonstrated that miR-140-3p overexpression reversed the inhibition of human chondrocyte proliferation, hypertrophy and endochondral ossification, caused by circRNA_0079201 overexpression. Bioinformatics analysis and luciferase reporter assays revealed that SMAD2 was a potential target gene of miR-140-3p. Furthermore, overexpressing circRNA_0079201 in human chondrocytes suppressed miR-140-3p and increased SMAD2 protein expression level. Taken together, chondrocyte proliferation, hypertrophy and endochondral ossification in ISS was suppressed by a novel regulatory axis consisting of the hsa_circRNA_0079201/miR-140-3p/SMAD2 pathway. The present study provided evidence that hsa_circRNA_0079201 may be a potential target for ISS therapy.

The Challenge of Defining and Investigating the Causes of Idiopathic Short Stature and Finding an Effective Therapy

Idiopathic short stature (ISS) comprises a wide range of conditions associated with short stature that elude the conventional diagnostic work-up and are often caused by still largely unknown genetic variants. In the last decade, the improvement of diagnostic techniques has led to the discovery of causal mutations in genes involved in the function of the growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis as well as in growth plate physiology. However, many cases of ISS remain idiopathic. In the future, the more frequent identification of the underlying causes will allow a better stratification of subjects and offer a tailored management. GH therapy has been proposed and approved in some countries for the treatment of children with ISS. To improve the efficacy of GH therapy, trials with GH combined with GnRH agonists, aromatase inhibitors, and even IGF-I have been conducted. This review aims to revise the current definition of ISS and discuss the management of children with ISS on the basis of the most recent evidence.

Genomic interrogation of familial short stature contributes to the discovery of the pathophysiological mechanisms and pharmaceutical drug repositioning

Background

Genetic factors, dysregulation in the endocrine system, cytokine and paracrine factors are implicated in the pathogenesis of familial short stature (FSS). Nowadays, the treatment choice for FSS is limited, with only recombinant human growth hormone (rhGH) being available.

Methods

Herein, starting from the identification of 122 genetic loci related to FSS, we adopted a genetic-driven drug discovery bioinformatics pipeline based on functional annotation to prioritize crucial biological FSS-related genes. These genes were suggested to be potential targets for therapeutics.

Results

We discovered five druggable subnetworks, which contained seven FSS-related genes and 17 druggable targerts.

Conclusions

This study provides a valuable drug repositioning accompanied by corresponding targetable gene clusters for FSS therapy.

The Rationale for Growth Hormone Therapy in Children with Short Stature

Growth hormone (GH) was first isolated from cadaver pituitary glands, requiring laborious and expensive collection of glands, followed by extraction and purification of the hormone. This limited supply restricted its use to children with severe GH deficiency who were treated with low dosages and suboptimal schedules. The development of recombinant DNA-derived GH, allowed the production of virtually unlimited amounts of GH, leading to the approval for therapy for a large number of childhood conditions characterized by non-GH deficient short stature. The aim of this review is to provide a critical overview on the daily use of GH in two paradigmatic conditions of non-GH deficient short stature which are children born small for gestational age and with idiopathic short stature, highlighting the available strength of evidence for efficacy and safety.

A 4-Year, Open-Label, Multicenter, Randomized Trial of Genotropin® Growth Hormone in Patients with Idiopathic Short Stature: Analysis of 4-Year Data Comparing Efficacy, Efficiency, and Safety between an Individualized, Target-Driven Regimen and Standard Dosing

BACKGROUND/AIMS

Growth hormone (GH) treatment regimens for children with non-GH-deficient, idiopathic short stature (ISS) have not been optimized. To compare the efficacy, efficiency, and safety of an individualized, target-driven GH regimen with standard weight-based dosing after 4 years of treatment.

METHODS

This is a 4-year, open-label, multicenter, randomized trial comparing individualized, formula-based dosing of Genotropin® versus a widely used ISS dose of Genotropin®. Subjects were prepubertal, had a bone age of 3-10 years for males and 3-9 years for females, were naive to GH treatment, and had a height standard deviation score (Ht SDS) of -3 to -2.25, a height velocity <25th percentile for their bone age, and peak stimulated GH >10 ng/ml. After the first 2 years, the individualized-dosing group was further randomized to either 0.18 or 0.24 mg/kg/week.

RESULTS

At 4 years, subjects in all treatment regimens achieved similar average height gains of +1.3 SDS; however, the individualized dosing regimen utilized less GH to achieve an equivalent height gain.

CONCLUSION

Individualized, formula-based GH dosing, followed by a dose reduction after 2 years, provides a more cost-effective growth improvement in patients with ISS than currently employed weight-based regimens.

Efficacy and Safety of Human Growth Hormone in Idiopathic Short Stature

OBJECTIVE

To explore the efficacy and safety of medium dose of recombinant human growth hormone (rhGH) in the treatment of prepubescent girls with idiopathic short stature (ISS).

METHODS

Fifty-one prepubescent girls with ISS were recruited into the study and divided into the treatment group (n = 27) and the control group (n = 24) depending on whether or not they accepted rhGH therapy respectively. A therapeutic dose of 0.35-0.42 mg of rhGH·(kg·wk)(-1) was administered for 2 y. The control group patients did not receive rhGH treatment. The height, growth rate, height standard deviation score (HtSDS), bone age (BA), the expected adult height (PAH), and potential side effects of rhGH treatment were analysed and compared between the groups.

RESULTS

The growth rate and htSDS during years 1 and 2 were significantly higher in the treatment group than in the control group. The expected adult height was significantly higher after 2 y of treatment as compared to the corresponding value in the control group. The BA after years 1 and 2 did not significantly differ between the two groups.

CONCLUSIONS

Thus, short-term therapy with a medium dose of rhGH was found to have a precise effect on prepubertal children with ISS. At this dose, it can significantly increase the growth rate of children and improve the expected adult height without accelerating bone maturation. No serious adverse reactions were found in association with rhGH use during the two-year study period.

A pilot study of growth hormone administration in boys with predicted adult short stature and near-ending growth

CONTEXT

The growth-promoting effect of starting recombinant human growth hormone (rhGH) at the time of near-ending growth has not been studied in sexually mature boys who will have idiopathic short stature (ISS) as adults because it is believed that such an advanced stage of puberty would preclude favorable results.

OBJECTIVES

1) To explore the effects of starting rhGH administration at time of near-ending growth in boys with ISS. 2) To search for predictors of response to rhGH.

SUBJECTS

Fifteen boys aged 15.5 ± 1 years terminating puberty were growing at a rate < 2 cm/6 months towards a predicted adult height (PAH) <-2.5 SDS.

METHODS

Participants received 0.50 ± 0.06 mg/kg · wk of rhGH according to a target-to-treat protocol. When growth became less than 0.5 cm in 3 months or when height has reached 169 cm, rhGH was ceased. Testosterone, growth velocity (GV), height, serum IGF-1, bone age (BA) at hand-wrist and knee score were measured at onset; IGF-1 and height were monitored every 3 months. A formula for PAH was developed. Height increment (HI, adult height-starting height) and height gain (HG, adult height-PAH) were calculated.

RESULTS

Following rhGH administration for 11.1 ± 4.8 months, GV-SDS increased from -2.5 ± 1.7 to 3.5 ± 4.3 (P = 2 × 10(-4)), HI = 8.5 ± 3.7 cm, HG = 6.8 ± 4.8 cm and adult height was -1.8 ± 0.9 SDS, compared to a PAH of -2.9 ± 0.6 SDS (P = 4 × 10(-4)). Knee score (P = 2 × 10(-3)), GV at rhGH onset (P = 8 × 10(-3)) and rhGH dose (P = 8 × 10(-3)) were identified as predictors of HI and HG, but BA was not.

CONCLUSIONS

Our study suggests that 1) a short period of rhGH administration can increase true adult height significantly in boys with ISS at time of near-ending growth; and 2) knee score rather than BA should be used to identify rhGH responders. These preliminary observations await confirmation by larger randomized trials.

A randomized pilot trial of growth hormone with anastrozole versus growth hormone alone, starting at the very end of puberty in adolescents with idiopathic short stature

BACKGROUND

When given during the course of puberty, anastrozole (A), an aromatase inhibitor, has been shown to increase the predicted adult height (PAH) of GH-deficient (GHD) boys treated with recombinant human growth hormone (rhGH). Our study questioned whether this treatment could retain some of its effects in non-GHD adolescent boys if started only at the very end of puberty, a time when rhGH treatment is denied to short adolescents who have almost reached their final height.

OBJECTIVE

To explore the effect on adult height of a combination of rhGH and A, compared with rhGH alone, at the end of puberty in boys with idiopatic short stature (ISS).

METHODS

A prospective randomized study comparing rhGH + A and rhGH was conducted in 24 healthy adolescent boys aged 15.2 ± 1.2 yrs with serum testosterone at adult levels and a faltering growth velocity <3.5 cm/yr leading to a predicted adult height (PAH) <2.5 SDS. Treatments were stopped when growth velocity became <10 mm in 6 months or when height was close to 170 cm. A historical group of ISS adolescents (N = 17) matched for puberty and growth was used for comparison.

RESULTS

IGF1 levels remained within normal limits in all treated patients. Mean treatment duration was 19 months in the rhGH + A group and 11.5 months in the rhGH group (P = 6.10(-4)). Adult height reached 168.4 ± 2.6 cm in the rhGH + A group and 164.2 ± 5.6 cm in the rhGH group (P < 0.02). Adult height was 160.1 ± 2.8 cm in the historical controls.

CONCLUSION

A combination of rhGH and A, started at the very end of puberty, seems to allow boys with ISS to reach a greater adult height than rhGH alone. Larger trials are needed to confirm this preliminary observation.

A four-year, open-label, multi-center, randomized, two-arm study of Genotropin® in patients with idiopathic short stature: comparison of an individualized, target-driven treatment regimen to standard dosing of Genotropin® - analysis of two-year data

BACKGROUND

Several models have been developed to predict growth response to growth hormone (GH) based on auxological and biochemical parameters for children with non-GH-deficient, idiopathic short stature (ISS).

OBJECTIVE

To demonstrate if an individualized, formula-based, target-driven GH regimen for children with ISS would lead to a height (Ht) gain to -1.3 SDS during the first 24 months of treatment of this 4-year study, with less variability than with standard weight-based dosing.

METHODS

A 4-year, open-label, multi-center, randomized, two-arm study comparing formula-based dosing of Genotropin® GH from 0.18 to 0.7 mg/kg/week versus standard FDA-approved ISS dosing of Genotropin® (0.37 mg/kg/week). Subjects (n = 316, 89 females) were prepubertal, 3-14 years of age, bone age 3-10 years (m) and 3-9 years (f), naive to GH treatment, Ht SDS -3 to -2.25, Ht velocity <25th percentile for bone age, and peak GH >10 ng/ml.

RESULTS

The majority (83%) of subjects had Ht SDS within the normal range by 2 years. All subjects displayed catch-up growth consistent with other studies of GH treatment of ISS.

CONCLUSION

The formula-based therapy did not meet the primary endpoint achieving targeted gain with lower variability. No new safety concerns were found.

Treatment of children and adolescents with idiopathic short stature

Idiopathic short stature (ISS) is defined as shortness in childhood without a specific cause. ISS may be familial or nonfamilial and may be associated with or without delay of pubertal development. Treatment can be considered in an attempt to reduce the psychological burden caused by short stature in childhood and adult life. If counselling alone is not sufficient, medical modifications of the growth process can be attempted. In cases with pubertal delay, sex steroids, such as testosterone and oxandrolone, can favourably influence height velocity and growth tempo, although adult height is not affected. Medications that prolong the process of growth--for example, gonadotropin-releasing hormone agonists or aromatase inhibitors--might increase adult height, but findings to date are still experimental. Growth hormone therapy is approved for the treatment of very short children with reduced adult height expectation, as evidence has accumulated that this therapy can increase height in childhood and in adult life. Sensitivity to growth hormone is impaired in patients with ISS; therefore, doses higher than a replacement dose have to be applied. This treatment still needs to be optimized in terms of efficacy, cost-effectiveness and long-term safety. A debate is ongoing concerning the psychological benefit of height increase, with clinicians warning against the medicalization of a deviation in height.

Clinical review: Lessons learned from the hGH era

Today, many medical interventions that begin as treatments for disease often expand into therapies that reduce disability, lessen disadvantage, or even confer advantage. Forces that propel profitable drugs, devices, and procedures dominate over considerations of efficient and equitable distribution of resources. This dominance is fueled by industry-physician collaborations often biased by prior assumptions, reliant on surrogate outcomes, and advantageous to marketing. Interventions are justified by "medicalization" of physiologic variations (e.g. short stature) as defects or disease, and nudged into "standard practice" by key opinion leaders. The story below of recombinant human growth hormone (hGH) treatment of short stature is one vivid example, but others (e.g. expansion of drug treatment to "optimize" cholesterol profiles, bone health, psychological well-being) can be found throughout medicine. In the new obesity era, lessons learned from the hGH era will be needed to keep the field of pediatric endocrinology empowered to make the key clinical decisions, and free of unintended consequences for patients and runaway health care inflation for society.