Long-Term Efficacy and Safety of Somatropin for Adult Growth Hormone Deficiency

Long-acting FC-fusion rhGH (GX-H9) shows potential for up to twice-monthly administration in GH-deficient adults

OBJECTIVE

Hybrid Fc-fused rhGH (GX-H9) is a long-acting recombinant human growth hormone (GH) under clinical development for both adults and children with GH deficiency (GHD). We compared the safety, pharmacokinetics and pharmacodynamics of weekly and every other week (EOW) dosages of GX-H9 with those of daily GH administration in adult GHD (AGHD) patients.

DESIGN

This was a randomized, open-label, active-controlled and dose-escalation study conducted in 16 endocrinology centers in Europe and Korea.

METHODS

Forty-five AGHD patients with or without prior GH treatment were enrolled. Patients with prior GH treatments were required to have received the last GH administration at least 1 month prior to randomization. Subjects were sequentially assigned to treatment groups. Fifteen subjects were enrolled to each treatment group and randomly assigned to receive either GX-H9 or Genotropin (4:1 ratio). GX-H9 dosage regimens for Groups 1, 2 and 3 were 0.1 mg/kg weekly, 0.3 mg/kg EOW and 0.2 mg/kg EOW, respectively. All Genotropin-assigned subjects received 6 µg/kg Genotropin, regardless of treatment group. Main outcome analyses included measurements of serum insulin-like growth factor 1 (IGF-I), safety, pharmacokinetics, pharmacodynamics and immunogenicity.

RESULTS

Mean GX-H9 peak and total exposure increased with an increase in dose after a single-dose administration. The mean IGF-I response was sustained above baseline over the intended dose interval of 168 h for the weekly and 336 h for the EOW GX-H9 groups. Safety profiles and immunogenicity were not different across the treatment groups and with Genotropin.

CONCLUSIONS

GX-H9 has the potential for up to twice-monthly administration.

Availability and quality of illegitimate somatropin products obtained from the Internet

Background Growth hormones are widely available on the Internet for those who want to enhance their physical performance and improve body satisfaction. Illegitimate websites market somatropin injections without medical prescription and encourage misuse. Customers potentially put their health at risk when purchasing parenteral medications online. Objective The objective of our study was to evaluate the online market of no-prescription somatropin products and to analyse and document Internet pharmacy characteristics, distribution and pharmaceutical quality. Setting Websites indexed in Google promoting somatropin for sale direct to patients. Method Websites promoting the sale of growth hormone products were identified and analysed from June to August 2014. Internet vendor sites were evaluated to identify possible patient and medication safety concerns. Website characteristics, delivery time, storage conditions, packaging and attached product information were assessed. Investigation of the somatropin content was achieved using capillary electrophoresis with UV detection and electrospray ionization mass spectrometry. Main outcome measure Accessibility and quality of somatropin injections. Results Seventeen individual Internet vendor websites distributed somatropin products directly to patients, majority (94%) did not require a valid medical prescription before dispensing the products. Majority (70%) of Internet pharmacies displayed no medical information and none (0%) of the vendors displayed any regulatory body logo. All online samples had significantly (p < 0.001) lower somatropin concentration than labelled. Conclusion Our results clearly illustrate that prescription only biologic drugs are widely available online and can be easily accessed by anyone. Unprofessional distribution and handling is likely to cause degradation and possible patient safety concerns.

Characteristics and outcomes of Italian patients from the observational, multicentre, hypopituitary control and complications study (HypoCCS) according to tertiles of growth hormone peak concentration following stimulation testing at study entry

OBJECTIVE

To determine whether characteristics and outcomes of Italian patients in the observational global Hypopituitary Control and Complication Study (HypoCCS) differed according to the degree of GH deficiency (GHD).

DESIGN

Patients were grouped by tertiles of stimulated GH peak concentration at baseline (Group A lowest tertile, n = 342; Group B middle tertile, n = 345; Group C highest tertile, n = 338).

RESULTS

Baseline demographics, lipid levels, body mass index categories and mean Framingham cardiovascular risk indexes were similar in the three groups and remained substantially unchanged over time, with no subsequent significant between-group differences (except mean levels of triglycerides increased in the highest tertile group). GHD was adult-onset for >75% of patients in all groups. The percentage of patients with multiple pituitary deficiencies was higher in Group A than in the other groups; isolated GHD was reported with highest frequency in Group C. Patients in Group A received the lowest mean starting dose of GH. Hyperlipidaemia at baseline was reported in 35·1%, 31·1% and 24·7% of patients in groups A, B and C, respectively (P = 0·029). Mean duration of GH treatment was 7·21, 5·45 and 4·96 years, respectively. The proportion of patients with adverse events did not differ significantly between groups, with a low prevalence over time of diabetes and cancer.

CONCLUSIONS

In Italian patients from HypoCCS, the level of GH deficit did not influence changes over time in metabolic parameters or adverse event profile, despite differences in GHD severity at baseline and in the starting GH dose.

Differential effects of growth hormone versus insulin-like growth factor-I on the mouse plasma proteome

The GH/IGF-I axis has both pre- and postpubertal metabolic effects. However, the differential effects of GH and/or IGF-I on animal physiology or the plasma proteome are still being unraveled. In this report, we analyzed several physiological effects along with the plasma proteome after treatment of mice with recombinant bovine GH or recombinant human IGF-I. GH and IGF-I showed similar effects in increasing body length, body weight, lean and fluid masses, and organ weights including muscle, kidney, and spleen. However, GH significantly increased serum total cholesterol, whereas IGF-I had no effect on it. Both acute and longer-term effects on the plasma proteome were determined. Proteins found to be significantly changed by recombinant bovine GH and/or recombinant human IGF-I injections were identified by mass spectrometry (MS) and MS/MS. The identities of these proteins were further confirmed by Western blotting analysis. Isoforms of apolipoprotein A4, apolipoprotein E, serum amyloid protein A-1, clusterin, transthyretin, and several albumin fragments were found to be differentially regulated by GH vs. IGF-I in mouse plasma. Thus, we have identified several plasma protein biomarkers that respond specifically and differentially to GH or IGF-I and may represent new physiological targets of these hormones. These findings may lead to better understanding of the independent biological effects of GH vs. IGF-I. In addition, these novel biomarkers may be useful for the development of tests to detect illicit use of GH or IGF-I.

Somatropin Therapy and Cognitive Function in Adults with Growth Hormone Deficiency

Both growth hormone (GH) and insulin-like growth factor (IGF)-I have receptors in the brain, in particular in areas that are involved in cognitive function. Therefore, it has been hypothesized that GH deficiency can lead to cognitive dysfunction, and that somatropin replacement therapy may have beneficial effects on cognitive function in GH-deficient patients. In this review, an overview is given regarding the possible effects of decreased activity of the GH/IGF-I axis and somatropin therapy in GH deficiency in relation to cognitive function. The available data regarding cognitive function in GH-deficient patients are limited, but suggest that this condition can lead to specific cognitive changes, in particular attentional deficits and altered processing speed. The underlying mechanisms and the effects of somatropin treatment on cognitive function in GH deficiency are still unclear. Similar studies to those performed in patients with GH deficiency have been performed regarding the cognitive changes in elderly patients with relatively low GH and/or IGF-I levels. Large controlled studies regarding the effects and safety of somatropin treatment in healthy elderly patients have not been performed.

Estrogen regulation of growth hormone action

GH plays a pivotal role in regulating body growth and development, which is modulated by sex steroids. A close interplay between estrogen and GH leads to attainment of gender-specific body composition during puberty. The physiological basis of the interaction is not well understood. Most previous studies have focused on the effects of estrogen on GH secretion. There is also strong evidence that estrogen modulates GH action independent of secretion. Oral but not transdermal administration of estrogen impairs the metabolic action of GH in the liver, causing a fall in IGF-I production and fat oxidation. This results in a loss of lean tissue and a gain of body fat in postmenopausal women and an impairment of GH effect in hypopituitary women on GH replacement. The negative metabolic sequelae are potentially important because of the widespread use of oral estrogen and estrogen-related compounds. Estrogen affects GH action at the level of receptor expression and signaling. More recently, estrogen has been shown to inhibit Janus kinase/signal transducer and activator of transcription signaling by GH via the induction of suppressor of cytokine signaling-2, a protein inhibitor for cytokine signaling. This represents a novel paradigm of steroid regulation of cytokine receptors and is likely to have significance for a diverse range of cytokine function.