Stabilizing Effects for Antibody Formulations and Safety Profiles of Cyclodextrin Polypseudorotaxane Hydrogels.

Antibodies often have poor physicochemical stability during storage and transport, which is a serious drawback for the development of antibody-based drugs. In this study, we prepared polypseudorotaxane (PPRX) hydrogels consisting of cyclodextrins (CyDs) and polyethylene glycol, and evaluated them as stabilizers for commercially available antibody-based drugs. α-CyD and γ-CyD formed PPRX hydrogels with polyethylene glycol (molecular weight 20,000 Da) in the presence of antibody-based drugs such as omalizumab, palivizumab, panitumumab, and ranibizumab. Importantly, both α- and γ-CyD PPRX hydrogel formulations provided high stabilizing effects (ca. 100%) to the all antibody-based drugs used in this study. Furthermore, approximately 100% of the binding activity of omalizumab to the immunoglobulin E receptor was retained after the release from the hydrogels. Plasma levels of omalizumab after subcutaneous injection of the γ-CyD PPRX hydrogel to rats were equivalent to those of omalizumab alone. According to the results of blood chemistry tests, the weights of organs and histological observations α- and γ-CyD PPRX hydrogels induced no serious adverse effects. These results suggest that CyD PPRX hydrogels are useful as safe and promising stabilizing formulations for antibody-based drugs.

Stress Tolerance of Antibody-Poly(Amino Acid) Complexes for Improving the Stability of High Concentration Antibody Formulations.

The stabilization of antibodies in aqueous solution against physical stress remains a problematic issue for pharmaceutical applications. Recently, protein-polyelectrolyte complex (PPC) formation using poly(amino acids) was proposed to prepare antibody formulation in a salt-dissociable precipitated state without protein denaturation. Here, we investigated the stabilization effect of PPC of therapeutic antibodies with poly-l-glutamic acid on agitation and thermal stress as forms of mechanical and non-mechanical stress, respectively. The precipitated state of PPC prevented the inactivation and aggregation induced by agitation. Similar results were obtained using the suspension state of PPC, but the stabilizing effects were slightly inferior to those of the PPC precipitate. PPC precipitate and PPC suspension prevented heat-induced inactivation of the antibodies, but showed little effect on heat-induced aggregation. Thus, PPC is a new candidate as a simple storage method for antibodies in aqueous solution, as an alternative state for freeze-drying.

Protein-poly(amino acid) precipitation stabilizes a therapeutic protein l-asparaginase against physicochemical stress.

Long-term storage in aqueous solution has been demanded for the practical application of therapeutic proteins. Recently, a precipitation-redissolution method was proposed to prepare salt-dissociable protein-polyelectrolyte complex (PPC). To elucidate the utility of the complex for storage of proteins, we investigated the stress tolerance of PPC precipitates containing l-asparaginase (ASNase) and poly-l-lysine (polyK). PPC precipitate containing ASNase and polyK was prepared by precipitation-redissolution method. The sample was treated to three types of stress, i.e., heat, shaking, and oxidation. The protein concentration, enzyme activity, and CD spectrum of the supernatants of samples were measured after stressed. PPC precipitate consisting of ASNase and polyK showed tolerance against thermal and shaking stress compared to the native solution. In addition, PPC precipitate protected ASNase from inactivation by oxidation. PPC precipitate of ASNase/polyK complex successfully stabilized ASNase against physicochemical stresses. These results suggest that the PPC precipitate has great potential as a storage method in aqueous solution for unstable proteins.

Feasibility of antibody-poly(glutamic acid) complexes: preparation of high-concentration antibody formulations and their pharmaceutical properties.

Development of high-concentration antibody formulations for subcutaneous administration remains challenging. Recently, a precipitation-redissolution method was proposed to prepare suspensions or precipitates of salt-dissociable protein-poly(amino acid) complexes. To elucidate the utility of this method for protein therapy, we investigated the feasibility of a precipitation-redissolution method using poly(amino acid) for high-concentration antibody formulation. Omalizumab and adalimumab formulations of 150 mg/mL could be prepared using poly-l-glutamic acid (polyE) from low-concentration stock solutions. Enzyme-linked immunosorbent assay, circular dichroism, and size-exclusion chromatography revealed that the formation of antibody-polyE complex and precipitation-redissolution process did not significantly affect the immunoreactivity or secondary structure of the antibodies. The precipitation-redissolution method was less time-consuming and more effective than lyophilization-redissolution, evaporation-redissolution, and ultrafiltration from the viewpoint of final yield. Scalability was confirmed from 400 µL to 1.0 L. The general toxicity and pharmacokinetic profiles of the antibody-polyE complex formulations were similar to those of conventional antibody formulations. These results suggested that the precipitation-redissolution method using poly(amino acid) has great potential as a concentration method for antibody formulation and medicinal use.

Design and Evaluation of the Highly Concentrated Human IgG Formulation Using Cyclodextrin Polypseudorotaxane Hydrogels.

To achieve the potent therapeutic effects of human immunoglobulin G (IgG), highly concentrated formulations are required. However, the stabilization for highly concentrated human IgG is laborious work. In the present study, to investigate the potentials of polypseudorotaxane (PPRX) hydrogels consisting of polyethylene glycol (PEG) and α- or γ-cyclodextrin (α- or γ-CyD) as pharmaceutical materials for highly concentrated human IgG, we designed the PPRX hydrogels including human IgG and evaluated their pharmaceutical properties. The α- and γ-CyDs formed PPRX hydrogels with PEG (M.W. 20,000) even in the presence of highly concentrated human IgG (>100 mg/mL). According to the results of (1)H-NMR, powder X-ray diffraction, and Raman microscopy, the formation of human IgG/CyD PPRX hydrogels was based on physical cross-linking arising from their columnar structures. The release profiles of human IgG from the hydrogels were in accordance with the non-Fickian diffusion model. Importantly, the stabilities of human IgG included into the hydrogels against thermal and shaking stresses were markedly improved. These findings suggest that PEG/CyD PPRX hydrogels are useful to prepare the formulation for highly concentrated human IgG.

Protein-poly(amino acid) complex precipitation for high-concentration protein formulation.

A method for concentration of protein solutions is required for high-dosage protein formulation. Here, we present a precipitation-redissolution method by poly(amino acid) for proteins, including therapeutic enzymes, antibodies, and hormones. The proteins were fully precipitated by the addition of poly-L-lysine or poly-L-glutamic acid at low ionic strength, after which precipitate was dissolved at physiological ionic strength. The activities and secondary structures of redissolved proteins, especially antibodies, were almost identical to the native state. The precipitation-redissolution method is a simple and rapid technique for concentration of protein formulations.

Three isozymes of peptidylarginine deiminase in the chicken: molecular cloning, characterization, and tissue distribution.

Peptidylarginine deiminase (PAD; EC 3.5.3.15) is a post-translational modification enzyme that catalyzes the conversion of protein-bound arginine to citrulline (deimination) in a calcium ion dependent manner. Although PADI genes are widely conserved among vertebrates, their function in the chicken is poorly understood. Here, we cloned and sequenced three chicken PADI cDNAs and analyzed the expression of their proteins in various tissues. Immunoblotting analysis showed that chicken PAD1 and PAD3 were present in cells of several central neuron system tissues including the retina; the chicken PAD2 protein was not detected in any tissue. We expressed recombinant chicken PADs in insect cells and characterized their enzymatic properties. The chicken PAD1 and PAD3 recombinant proteins required calcium ions as an essential cofactor for their catalytic activity. The two recombinant proteins showed similar substrate specificities toward synthetic arginine derivatives. By contrast to them, chicken PAD2 did not show any activity. We found that one of the conserved active centers in mammalian PADs had been altered in chicken PAD2; we prepared a reverse mutant but we did not detect an activity. We conclude that chicken PAD1 and PAD3 might play specific roles in the nervous system, but that chicken PAD2 might not be functional under normal physiological conditions.