Download Delivery of Human Growth Hormone via DSM`s Polyesteramide

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