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Delivery of Human Growth Hormone via DSM’s Polyesteramide Julien Bérard [1]; John Zupancich[1]; A. Hecka [1]; A. Kemp [1]; M. Muller [1]; G. Mihov [1]; S. Reiver [1]; K. Messier [1]; J. Thies [1]; B. Wirostko [2]; M.J. Rafii [2] [1] DSM, Koestraat 1 6167 RA Geleen, The Netherlands [2] Jade Therapeutics, LLC, Park City, Utah, USA Introduction Generation OF rhGH-loaded PEA fibers The sustained release of therapeutic biologics provide unique opportunities for the treatment of various pathologies.1 However, the development of efficacious drug delivery systems for biologics remains a prodigious challenge, due in part to the sensitivity of these therapeutics to their local environment. rhGH-loaded, multi-layer constructs were prepared via encapsulation of solid protein within PEA matrices through use of an innovative film formation and assembly process (Figure 3). Constructs were subsequently shaped into fibers with dimensions that facilitate passage through a 27 gauge needle (Figure 4). Epithelial renewal is an essential phase of the corneal wound healing process, as reestablishment of the barrier property of this tissue insures protection of the corneal interior. Epithelial renewal involves reorganization, migration and proliferation of epithelial cells, and has been shown to be stimulated by a number of topically applied growth factors including epidermal growth factor and fibroblast growth factor.2 Recombinant human growth hormone (rhGH; 22 kDa) is approved by the US FDA for the treatment of numerous indications (e.g., growth hormone deficiency)3 and is available via prescription in a variety of formulations (i.e., liquid or solid). rhGH has also been shown to increase of rate of reepithelialization of skin graft donor sites, speeding the wound healing process.4 B A Figure 1: Placement of the Drug Delivery System A thin, protein-loaded PEA fiber is to be implanted into the subconjunctival space, facilitating the local delivery of rhGH. Figure 4: Images of rhGH-loaded PEA fiber A. The fiber has injectable dimensions of 3 mm length and diameter < 0.2mm B. SEM fiber cross-section; Individual layers of the construct as well as homogeneous solid protein dispersion is visible. Figure 3: Schematic representation of the lamination-based solvent extraction method used to generate rhGH-loaded PEA films and fibers • Process employs low temperatures & pressures • Limited exposure of protein to organic solvents • Homogeneous dispersion of solid protein in PEA matrix Multilayer construct w/o diffusion layer Multilayer construct w/ diffusion layer Performance evaluation Fibrillar, degradable polymer-based constructs for the local, sustained delivery of recombinant human growth hormone (rhGH) were generated. The safety, tolerability and possible efficacy of subconjunctivally placed devices (Figure 1) was evaluated in a rabbit debridement model. rhGH was selected based on an ability to up-regulate and modulate various growth factors (i.e., insulin growth factor, epidermal growth factor) that have been shown to be involved in corneal re-epithelialization. Construct in vitro release performance was evaluated over a period of 30 days (figure 5). In vivo experiments compared pea/rhgh (~12ug/device) and pea (i.E., Blank) constructs placed subconjunctival, perilimbal to BSS and topical rhgh (100ug/ml) delivered four times daily in a standardized rabbit corneal epithelial debridement model (N=9, 18 eyes). Safety and tolerability were assessed daily and histopathology was performed on day 7 (figure 6). Figure 6: Histopathology Findings for Invivo Implants. NSF=No Significant Findings \In vivo results in New Zealand white rabbit model showed PEA/rhGH and PEA constructs were well tolerated, with histopathology on all eyes revealing normal healing with no inflammation (Figure 5). An efficacy signal was difficult to ascertain due to the small number of animals utilized in the current study. Poly(ester amide) DSM’s versatile amino-acid based poly(ester amide) (PEA) materials (Figure 2) platform provides distinct advantages in the formulation of degradable devices for controlled release. • • • • • • Figure 2: Structure of Poly(ester amide) The chemical structure of PEAIII and the constitutive amino acid, diol, and diacid building blocks. Natural building blocks Control over polymer structure Control over material hydrophilic/hydrophobic balance Tunable material degradation rate Predictable degradation products Maintains neutral microenvironment during degradation Contact: DSM Biomedical Koestraat 1 6167 RA Geleen The Netherlands www.dsm.com/medical 100% Cumulative release [%] Purpose 75% 50% 25% 0% 0 7 14 21 Time point [Days] 28 35 Figure 5: Cumulative release of rhGH from multilayer PEA devices. The conc. of rhGH in the release medium as determined by SEC-HPLC. The release is expressed in percentage of theoretical rHGH-load. Advances in multi-layer construct design reveal the potential to sustain the release of rhGH for multiple weeks. No aggregated protein measured in release samples References Conclusions PEA fibers show excellent biocompatibility in the ocular setting. rhGH was successfully incorporated into PEA matrices through use of a unique protein-friendly film formation process. Released rhGH showed no evidence of aggregation and cell assay results confirmed the protein remained bioactive after encapsulation and release. Advanced methods of construct fabrication have shown the potential to extend rhGH release duration to weeks. Subconjunctivally placed rhGH-loaded PEA fibers were well tolerated in vivo and no histopathologic concerns were identified. In order to test efficacy, a preclinical model of impaired wound healing, such as an alkali burn, should be utilized. Study results indicate that PEA could be a viable polymer for the sustained delivery of proteins to the eye. 1. Pisal, D. et al. Delivery of Therapeutic Proteins. Journal of Pharmaceutical Sciences, 2010, 99, 2557–2575. 2. Lu, L. et al. Corneal Epithelial Wound Healing. Society for Experimental Biology and Medicine, 2001, 226, 653-664. 3. Richmond, E. et al. Current Indications for Growth Hormone Therapy for Children and Adolescents, in: Hindmarsh, P.C. (ed), Current Indications for Growth Hormone Therapy, ed 2, revised. Endocr Dev. Basel, Karger, 2010, 18, 92-108. 4. Demling, R.H. The Role of Anabolic Hormones for Wound Healing in Catabolic States. Journal of Burns and Wounds, 2005, 4, 46-62. 5. Tanaka. T. et. al. A New Sensitive and Specific Bioassay for Lactogenic Hormones: Measurement of Prolactin and Growth Hormone in Human Serum. J. Clin. Endocrinol. Metab.1980, 51, 1058-1063