Modified Human Growth Hormone

Abstract

Modified growth hormone polypeptide and uses thereof are provided.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. provisional patent application 60 / 638,616 filed Dec. 22, 2004 and U.S. provisional patent application 60 / 727,996 filed Oct. 17, 2005, the specifications of which are incorporated herein in their entirety.FIELD OF THE INVENTION [0002] This invention relates to growth hormone polypeptides modified with at least one non-naturally-encoded amino acid. BACKGROUND OF THE INVENTION [0003] The growth hormone (GH) supergene family (Bazan, F. Immunology Today 11: 350-354 (1990); Mott, H. R. and Campbell, I. D. Current Opinion in Structural Biology 5: 114-121 (1995); Silvennoinen, O. and Ihle, J. N. (1996) SIGNALING BY THE HEMATOPOIETIC CYTOKINE RECEPTORS) represents a set of proteins with similar structural characteristics. Each member of this family of proteins comprises a four helical bundle, the general structure of which is shown in FIG. 1. While there are still more members of the family yet to be iden...

AI Technical Summary

Benefits of technology

[0033] In some embodiments, the GH, e.g., hGH polypeptide comprises a substitution, addition, or deletion that increases the aqueous solubility of the GH, e.g., hGH polypeptide when compared to aqueous solubility of the corresponding GH, e.g., hGH without the substitution, addition, or deletion. In some embodiments, the GH, e.g., hGH polypeptide comprises a substitution, addition, or deletion that increases the solubility of the GH, e.g., hGH polypeptide produced in a host cell when compared to the solubility of the corresponding GH, e.g., hGH without the substitution, addition, or deletion. In some embodiments, the GH, e.g., hGH polypeptide comprises a substitution, addition, or deletion that increases the expression of the GH, e.g., hGH polypeptide in a host cell or increases synthesis in vitro when compared to the expression or synthesis of the corresponding GH, e.g., hGH without the substitution, addition, or deletion. In some embodiments, the hGH polypeptide comprises an amino acid substitution G120A. The hGH polypeptide comprising this substitution retains agonist activity and retains or improves expression levels in a host cell. In some embodiments, the GH, e.g., hGH polypeptide comprises a substitution, addition, or deletion that increases protease resistance of the GH, e.g., hGH polypeptide when compared to the protease resistance of the corresponding GH, e.g., hGH without the substitution, addition, or deletion.

[0053] The present invention also provides methods of increasing therapeutic half-life, serum half-life or circulation time of GH, e.g., hGH polypeptides. The present invention also provides methods of modulating immunogenicity of GH, e.g., hGH polypeptides. In some embodiments, the methods comprise substituting a non-naturally encoded amino acid for any one or more amino acids in naturally occurring GH, e.g., hGH polypeptides and / or linking the GH, e.g., hGH polypeptide to a linker, a polymer, a water soluble polymer, or a biologically active molecule.

[0063] In yet other embodiments, the invention provides a method of making a GH, e.g., hGH linked via an oxime bond to a water-soluble polymer comprising contacting a GH, e.g., hGH that comprises a NEAA comprising a carbonyl group with a PEG oxyamine under conditions suitable for formation of an oxime bond. The NEAA can contain a ketone group, e.g., a carbonyl. The NEAA can be para-acetylphenylalanine. In some embodiments containing a para-acetylphenylalanine, the para-acetylphenylalanine is substituted at a position in the GH, e.g., hGH corresponding to amino acid 35 in SEQ ID NO: 2. In some embodiments, the PEG oxyamine is a monomethoxyPEG (MPEG) oxyamine. In some embodiments, the MPEG oxyamine is linear, e.g., a linear MPEG of about 20-40 kDa, or about 30 kDa. In some embodiments, the MPEG oxyamine is a linear 30 kDa monomethoxy-PEG-2-aminooxy ethylamine carbamate hydrochloride. In some embodiments, the GH, e.g., hGH comprising an NEAA is made by introducing (i) a nucleic acid encoding a GH, e.g., hGH wherein the nucleic acid has been modified to provide a selector codon for incorporation of the NEAA; and (ii) the NEAA; to an organism whose cellular machinery is capable of incorporating the NEAA into a protein in response to the selector codon of the nucleic acid of (i). In some embodiments, the reaction conditions for forming the oxime bond include mixing the MPEG and GH, e.g., hGH to produce a MPEG-GH, e.g., hGH mixture with a MPEG:GH, e.g., hGH ratio of about 5 to 10, a pH of about 4 to 6; and gentle stirring of the MPEG-GH, e.g., MPEG-hGH mixture for about 10 to 50 hours at room temperature. In some embodiments, the method further includes purifying the GH, e.g., hGH, e.g., to at least about 99% pure.

Problems solved by technology

A significant challenge to using growth hormone as a therapeutic, however, is that the protein has a short in vivo half-life and, therefore, it must be administered by daily subcutaneous injection for maximum effectiveness (MacGillivray, et al., J. Clin. Endocrinol. Metab.

While the depot permits less frequent administration (once every 2-3 weeks rather than once daily), it is also associated with undesirable side effects, such as decreased bioavailability and pain at the injection site and was withdrawn from the market in 2004.

Although several of the amino acid side chain residues in Pegvisomant™ are derivatized with polyethylene glycol (PEG) polymers, the product is still administered once-daily, indicating that the pharmaceutical properties are not optimal.

In addition to PEGylation and depot formulations, other administration routes, including inhaled and oral dosage forms of hGH, are under early-stage pre-clinical and clinical development and none have yet received approval from the FDA.

Proteins and other molecules often have a limited number of reactive sites available for polymer attachment.

To form conjugates having sufficient polymer molecular weight for imparting the desired advantages to a target molecule, prior art approaches have typically involved random attachment of numerous polymer arms to the molecule, thereby increasing the risk of a reduction or even total loss in bioactivity of the parent molecule.

These PEG derivatives all have the common limitation, however, that they cannot be installed selectively among the often numerous lysine residues present on the surfaces of proteins.

This can be a significant limitation in instances where a lysine residue is important to protein activity, existing in an enzyme active site for example, or in cases where a lysine residue plays a role in mediating the interaction of the protein with other biological molecules, as in the case of receptor binding sites.

A second and equally important complication of existing methods for protein PEGylation is that the PEG derivatives can undergo undesired side reactions with residues other than those desired.

This can create complex, heterogeneous mixtures of PEG-derivatized bioactive molecules and risks destroying the activity of the bioactive molecule being targeted.

This approach is complicated, however, in that the introduction of a free sulfhydryl group can complicate the expression, folding and stability of the resulting protein.

As can be seen from a sampling of the art, many of these derivatives that have been developed for attachment to the side chains of proteins, in particular, the —NH2 moiety on the lysine amino acid side chain and the —SH moiety on the cysteine side chain, have proven problematic in their synthesis and use.

Some form unstable linkages with the protein that are subject to hydrolysis and therefore decompose, degrade, or are otherwise unstable in aqueous environments, such as in the bloodstream.

Some are somewhat toxic and are therefore less suitable for use in vivo.

Some are too slow to react to be practically useful.

Some result in a loss of protein activity by attaching to sites responsible for the protein's activity.

Some are not specific in the sites to which they will attach, which can also result in a loss of desirable activity and in a lack of reproducibility of results.

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