Growth and Growth Hormone through the Ages: Art and Science.

BACKGROUND: People have long been fascinated with the size and growth of living things, from the giants of classic mythology and art to the little people who also have appeared in classical art, as well as the courts of European monarchs, and were exploited in "shows." Serious medical evaluation began in the late 19th century with the description of acromegaly and its association with pituitary tumors. In the early 20th century, multiple investigators attempted to extract a growth-promoting factor from the anterior pituitary and then, over the decades, to purify it and distinguish it from other anterior pituitary hormones. With relatively pure growth hormone (GH), its biological activity in growth promotion and as a metabolic hormone were studied, and species specificity became apparent: primate GH was the only GH active in man. Human GH was prepared from cadaveric pituitaries and distributed by the NIH to treat children with GH deficiency, but there was never enough pituitary hGH for all of the children who required it. When Creutzfeldt-Jakob disease was found in some patients who received pituitary GH, the production and FDA approval of biosynthetic hGH dramatically accelerated. With a large supply, one could treat those who were GH deficient and test its efficacy in other causes of short stature; longer acting versions of hGH have now been developed, tested, and in a few instances received FDA approval. SUMMARY: It has been a long journey from the description of over- and underproduction of GH in animals to the production and clinical use of the biosynthetic hormones. KEY MESSAGES: The efforts of basic scientists led to the extraction and purification of GH. Clinical scientists have expanded the appropriate use of hGH for short children with conditions in addition to GH deficiency.

Changes in Manufacturing Processes of Biologic Therapies Can Alter the Immunogenicity Profile of the Product.

Manufacturing process changes may alter the characteristics of a protein therapeutic. In 2009, somatropin (version 1.0), a recombinant human growth hormone therapeutic, underwent a manufacturing update (version 1.1). The immunogenicity of somatropin version 1.1 as a daily subcutaneous injection was evaluated in 2014 in a prospective, open-label, single-arm clinical study of treatment-naive pediatric patients with idiopathic human growth hormone deficiency for 1 year. The primary end point was the proportion of patients who developed antidrug antibodies (ADAs) after treatment. Eighty-two patients were enrolled. The mean (SD) treatment duration was 347 (53) days. The incidence of ADAs was 3.7%. No neutralizing antibodies were observed in the three patients with ADA-positive samples. Two patients (2.6%) had growth attenuation, but they were not ADA positive. The manufacturing changes for somatropin version 1.1 resulted in a similar safety and efficacy profile compared with somatropin version 1.0 and a different immunogenicity profile with a lower incidence of ADAs.

Preparation and in vivo pharmacokinetics of rhGH-loaded PLGA microspheres.

Recombinant human growth hormone (rhGH) therapy must be administered as a daily injection due to its short half-life. To achieve sustained release of rhGH, the preparation of rhGH-loaded PLGA microspheres was investigated, and the influence of various factors on encapsulation efficiency was tested, including rhGH concentration, the ratio of internal phase to organic phase, stirring speed, PVA concentration, surrounding pH value, and the type of emulsifier and organic solvent. A pharmacokinetic study was performed by subcutaneous administration to explore the sustained release effect. It was found that rhGH-loaded PLGA microspheres were prepared with a narrow size distribution, and optimization of the formulation could enhance encapsulation efficiency. FTIR analysis indicated that the activity of rhGH was maintained after encapsulation. The pharmacokinetic behavior of rhGH solutions was consistent with a two-compartment model, which showed fast absorption and distribution. RhGH-loaded PLGA microspheres achieved a higher bioavailability and a long-term effective concentration by controlling the release, and PLGA 50/50 demonstrated favorable AUC compared with PLGA 75/25. Nevertheless, the higher bioavailability of rhGH-loaded PLGA microspheres lacking Span 80 did not predicate better sustained release behavior, indicating that further investigation is needed to explore the use of bioavailability as the standard in evaluating the sustained release characteristics and in vivo behavior of microspheres.

Development and Characterization of Sodium Hyaluronate Microparticle-Based Sustained Release Formulation of Recombinant Human Growth Hormone Prepared by Spray-Drying.

The purpose of this study was to develop and characterize a sodium hyaluronate microparticle-based sustained release formulation of recombinant human growth hormone (SR-rhGH) prepared by spray-drying. Compared to freeze-drying, spray-dried SR-rhGH showed not only prolonged release profiles but also better particle property and injectability. The results of size-exclusion high-performance liquid chromatography showed that no aggregate was detected, and dimer was just about 2% and also did not increase with increase of inlet temperature up to 150 °C. Meanwhile, the results of reversed-phase high-performance liquid chromatography revealed that related proteins increased slightly from 4.6% at 100 °C to 6.3% at 150 °C. Thermal mapping test proved that product temperature did not become high to cause protein degradation during spray-drying because thermal energy was used for the evaporation of surface moisture of droplets. The structural characterization by peptide mapping, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and circular dichroism revealed that the primary, secondary, and tertiary structures of rhGH in SR-rhGH were highly comparable to those of reference somatropin materials. The biological characterization by rat weight gain and cell proliferation assays provided that bioactivity of SR-rhGH was equivalent to that of native hGH. These data establish that spray-dried SR-rhGH is highly stable by preserving intact rhGH and hyaluronate microparticle-based formulation by spray-drying can be an alternative delivery system for proteins.

Preparation, characterization and molecular modeling of PEGylated human growth hormone with agonist activity.

In this study, site-specific PEGylated human growth hormone (hGH) was prepared by microbial transglutaminase, modeled and characterized. To this end, the effects of different reaction parameters including reaction media, PEG:protein ratios, reaction time and pH value were investigated. PEG-hGH was purified by size exclusion chromatography method and analyzed by SDS-PAGE, BCA, peptide mapping, ESI and MALDI-TOF-TOF mass spectroscopy methods. Biophysical and biological properties of PEG-hGH were evaluated. Molecular simulation was utilized to provide molecular insight into the protein-receptor interaction. The optimum conditions that were obtained for PEGylation were phosphate buffer with pH of 7.4, 48 h of stirring and PEG:protein ratio of 40:1. By this method, mono-PEG-hGH with high reaction yield was obtained and PEGylation site was at Gln-40 residue. The circular dichroism and fluorescence spectrum indicated that PEGylation did not change the secondary structure while tertiary structure was altered. Upon enzymatic PEGylation, agonistic activity of hGH was preserved; however, Somavert(®), which is prepared by chemical PEGylation, is an antagonist form of protein. These data were confirmed by the total energy of affinity obtained by computational protein-receptor interaction. In conclusion, PEGylation of hGH was led to prepare a novel form of hormone with an agonist activity which merits further investigations.

Medical innovation, unmet medical needs, and the drug pipeline.

This paper outlines and illustrates the working of a theoretical approach from the social sciences for analyzing medical innovation, unmet medical need, and the drug pipeline. Using the social history of three drugs made from recombinant DNA (insulin, human growth hormone, and tissue-plasminogen activator) the paper shows how drugs can be both technically and organizationally efficient while the needs they satisfy can be created or identified. The paper posits that drugs that require more organizational efficiency tend to satisfy identified, rather then created needs. Key words: Recombinant DNA, technical efficiency, organizational efficiency, anthropology.

Discovery and mechanism of action of pegvisomant.

Using a structure-function approach to the understanding of the molecular topology of the GH molecule, we discovered that glycine in the third alpha-helix of GH (G119 of bovine GH and G120 of human GH) was an important amino acid required for GH action. Substitution of this glycine residue with a variety of amino acids results in molecules that lack growth-promoting activity. More importantly, these molecules inhibit the actions of GH both in vitro and in vivo. These results, obtained more than a decade ago, were the basis for the discovery of GH antagonists. Since that time, efforts have been focused on establishing the mechanism by which these antagonists inhibit GH action. In this regard, in vivo expression of GH-antagonist genes in transgenic mice results in dwarf animals. The animals are fertile and possess no abnormal 'phenotypes'. Dwarf mice have also been created by disrupting or 'knocking out' the GH receptor gene. Together, these results have laid the foundation for the clinical use of GH antagonists when endogenous GH levels are increased or when GH is known to be a factor in the progression of the disorder.

Preparation of a copoly (dl-lactic/glycolic acid)-zinc oxide complex and its utilization to microcapsules containing recombinant human growth hormone.

A procedure to prepare a complex of copoly (dl-lactic/glycolic acid) and zinc oxide (PLGA-zinc oxide complex) was developed. Out of sparingly water-soluble zinc compounds, zinc oxide was most remarkably soluble in a PLGA/dichloromethane solution and the dissolution rates became faster as the water contents in the PLGA/dichloromethane solutions increased. Since the solubility of zinc oxide was saturated at approximately 0.5-fold molar ratio to PLGA and water was generated with dissolution of zinc oxide in the PLGA/dichloromethane solutions, it is suggested that zinc oxide interacts with the terminal carboxyl group of PLGA. In addition, the glass-transition temperature of a solid material obtained by vacuum-drying the PLGA/dichloromethane solution dissolving zinc oxide became higher as the zinc content increased, suggesting that the formation of a PLGA-zinc oxide complex. Microcapsules were prepared with the PLGA-zinc oxide complex using recombinant human growth hormone (rhGH) in order to evaluate an effect of the complex on protein release and stability of protein in the microcapsules. Released rhGH amount from the microcapsules prepared with the PLGA-zinc oxide complex after subcutaneous administration in rats was significantly larger than that from microcapsules prepared with PLGA alone, indicating that rhGH molecules in the microcapsules was stabilized by the PLGA-zinc oxide complex.

Structure and in vivo activity of hypoglycaemic analogues of human growth hormone (6-13).

A range of peptide analogues related to Asu11-human growth hormone (6-13) have been synthesized and tested for hypoglycaemic activity using in vivo insulin tolerance tests. Utilising an alanine scan procedure and a selective amino acid residue approach these structure-activity studies suggest that residues Phe10, Arg8 and the C-terminal beta-turn structure are important for the expression of biological activity.