WO2010078376A2

WO2010078376A2 - Fc-specific polymer-conjugated antibodies and their diagnostic use

Info

Publication number: WO2010078376A2
Application number: PCT/US2009/069748
Authority: WO
Inventors: Casey A. Kernag; Christopher Bieniarz; Danielle Brands; Julia Ashworth-Sharpe
Original assignee: Ventana Medical Systems, Inc.
Priority date: 2008-12-30
Filing date: 2009-12-29
Publication date: 2010-07-08
Also published as: WO2010078376A3

Abstract

The present invention provides molecular conjugates of antibodies and hydrophilic, non-immunogenic polymers. More particularly, the present invention provides Fc-specific polymer-conjugated antibody signal- generating moiety conjugates and methods for making and using the conjugates.

Description

FC-SPECIFIC POLYMER-CONJUGATED ANTIBODIES AND THEIR DIAGNOSTIC USE

BACKGROUND

Technical Field

The present invention relates to molecular conjugates and methods for making and using the conjugates. More particularly, the present invention relates to Fc-specific polymer-conjugated (e.g., PEGylated) antibodies and their diagnostic use.

Description of the Related Art

The term "PEGylation" refers to the modification of biological molecules by covalent conjugation with polyethylene glycol (PEG), a non-toxic, non-immunogenic polymer. PEGylation is used as a strategy to overcome particular disadvantages associated with some biopharmaceuticals. PEGylation can change the physical and chemical properties of the biological molecule, such as its conformation, electrostatic binding, hydrophobicity, and pharmacokinetic profile. In general, PEGylation improves drug solubility and decreases immunogenicity. PEGylation also increases drug stability and the retention time of the conjugates in blood, and reduces proteolysis and renal excretion, thereby allowing a reduced dosing frequency. In order to benefit from these favorable pharmacokinetic consequences, a variety of therapeutic proteins, peptides, and antibody fragments, as well as small molecule drugs, have been PEGylated.

A number of properties of the PEG polymer-e.g. mass, number of linking chains, the molecular site of PEG attachment-have been shown to affect the biological activity and bioavailability of the PEGylated product. Releasable PEGs have been designed to slowly release the native protein from the conjugates into the blood, aiming at avoiding any loss of efficacy that may occur with stable covalent PEGylation. Since the first PEGylated drug was developed in the 1970s, PEGylation of therapeutic proteins has significantly improved the treatment of several chronic diseases, including hepatitis C, leukemia, severe combined immunodeficiency disease, rheumatoid arthritis, and Crohn's disease.

In general, conjugation of a relatively large molecular weight polymer (50-50OkDa) such as PEG to a biological molecule, such as a protein, is accomplished through either chemical modification or through enzymatic coupling. For example, site-specific incorporation of PEG has been described using transglutaminases (Sato, Enzymatic Procedure for Site Specific Pegylation of Proteins. Adv. Drug DeNv. Rev. 2002, 54, 487-504). However, the use of such enzymes can affect the affinity of proteins (e.g., antibodies) and prevent strong binding to the desired target. With respect to chemical modification, many studies have examined the random binding of the PEG to available lysine residues. However, the random attachment of a PEG polymer non-specifically to an antibody can lead to losses in overall antibody affinity (Chapman. Pegylated Antibodies and Antibody Fragments for Improved Therapy: A Review. Adv. Drug Deliv. Rev. 2002, 54, 531-545).

Since much of the activity and half-life of an antibody is reflected in the lack of steric hindrance around the binding region and the conserved region, many of the strategies for PEGylation of therapeutic antibodies have involved the use of antibody fragments engineered to have a free cysteine that acts as a point of attachment for a maleimido-PEG compound (Chapman, 2002; Roberts et a/., Chemistry for Peptide and Protein PEGylation. Adv. Drug Deliv. Rev 2002, 54, 459-476.

Conjugation of PEG has also been described at glycosylation sites in the Fc region of antibodies. For example, U.S. Patent Application Publication No. 2006/0246523 discloses the use of conjugates, wherein an antibody is covalently linked to a signal-generating moiety through a heterobifunctional polyalkyleneglycol linker, such as a heterobifunctional polyethyleneglycol (PEG) linker. The PEG is conjugated to the Fc portion of the antibody, however the PEG functions solely as a linker whose function is to reduce the crowding of signal-generating moieties around the antibody, thereby preserving antibody activity.

Thus, PEGylation of proteins and other biological molecules with high molecular weight PEG polymers has mainly been exploited for therapeutic indications. In contrast, the use of PEG to advantageously modify proteins in diagnostic applications has not been fully understood or developed. The present invention addresses these needs and offers other related advantages.

BRIEF SUMMARY

Fc-specific polymer-conjugated (e.g., PEGylated) antibodies optionally conjugated to signal-generating moieties are disclosed, as are methods for making and using same. The disclosed antibody conjugates exhibit superior performance for detection of molecules of interest in biological samples, especially for detection of such molecules in tissue sections and cytology samples. In particular, Fc-specific polymer-conjugated antibodies and conjugates of the invention retain high levels of antibody specificity and detectability, and thereby provide more intense staining with less background than conjugates currently used for detection of target molecules in biological samples.

Therefore, according to one aspect of the present invention, an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate is provided, said conjugate comprising one or more derivatives of hydrophilic, non-immunogenic polymers covalently bound to oligosaccharide moieties in a glycosylated region of the Fc portion of an antibody; and one or more signal- generating moieties covalently bound to the antibody. In certain embodiments, the signal-generating moieties are covalently bound to the antibody via moieties other than said polymers.

The hydrophilic, non-immunogenic polymers used according to the invention can be selected from any of a variety of polymers provided they do not substantially alter the specificity of the antibody and provided they achieve the advantages and objectives described herein (e.g., reduced background staining) Illustrative polymers, for example, may include, but are not limited to, homopolymers selected from the group consisting of polyvinyl alcohol) (PVA), poly(acrylιc acid), poly(methacrylιc acid), poly(acrylamιde), polyvinyl pyrrolidinone), and polyethylene glycol (PEG) Alternatively, or in addition, the hydrophihc, non-immunogenic polymers can be selected from heteropolymers comprising at least one monomeric subunit from two or more of the polymers selected from the group consisting of polyvinyl alcohol) (PVA), poly(acrylιc acid), poly(methacrylιc acid), poly(acrylamιde), polyvinyl pyrrolidinone), and polyethylene glycol (PEG) In a particular embodiment of interest, the hydrophihc, non- immunogenic polymer comprises PEG and, therefore, the Fc-specific polymer- conjugated antibody is an Fc-specific PEGylated antibody

Although the size of the hydrophihc, non-immunogenic polymers used in the conjugates of the invention can vary while still providing the advantages described herein, in certain embodiments, the molecular weight of the hydrophihc, non-immunogenic polymers bound to an antibody is less than 2 kDa In certain other embodiments, the molecular weight of each of the polymers is less than 1 5 kDa In further embodiments, the molecular weight of each of the polymers is less than 1 kDa In still further embodiments, the molecular weight of each of the polymers is less than 0 5 kDa

In more specific embodiments of this aspect of the invention, there are provided Fc-specific PEGylated antibodies comprising one or more PEG derivatives covalently bound to oligosaccharide moieties in a glycosylated region of the Fc portion of the antibodies, and optionally further comprising one or more signal-generating moieties covalently bound to the antibodies, e g , via moieties other than said PEG derivatives

In other particular embodiments, Fc-specific PEGylated antibody signal-generating moiety conjugates of the present invention comprise one or more PEG derivatives covalently bound to aldehyde groups in a glycosylated region of the Fc portion of an antibody In still other particular embodiments, Fc-specific PEGylated antibody signal-generating moiety conjugates of the present invention comprise one or more signal generating moieties that are thiol reactive signal-generating moieties covalently bound to a thiol group formed on the antibody. In certain other embodiments, Fc-specific PEGylated antibody signal-generating moiety conjugates of the present invention comprise one or more PEG derivatives that covalently bind to aldehyde groups of the antibody, said PEG derivatives having the formula: Y-A-PEG_m-B-X. The skilled artisan would recognize that the PEG derivatives of the present invention have the foregoing formula prior to reacting with aldehyde groups in the glycosylated region of the Fc portion of an antibody. In the above formula, Y comprises a nucleophilic group selected from the group consisting of: an amino group, a hydrazide group, a carbohydrazide group, a semicarbazide group, a thiosemicarbazide group, a thiocarbazide group, a carbonic acid dihydrazine group, and a hydrazine carboxylate group; X comprises -CH2CH2OCH3 or - CH2CH2OH; wherein the subscript m = 1 to 50; and A and B each independently comprise from 0 to 10 carbon atoms.

In certain related embodiments, Fc-specific PEGylated antibody signal-generating moiety conjugates of the present invention comprise a PEG derivative having the formula: Y-A-PEG_m-B-X, wherein the molecular weight of the PEG polymer (e.g., PEG_m) of each PEG derivative is less than 2 kDa. In other related embodiments, the molecular weight of the PEG polymer of each PEG derivative is less than 1.5 kDa. In still other related embodiments, the molecular weight of the PEG polymer of each PEG derivative is less than 1 kDa. In further related embodiments, the molecular weight of the PEG polymer of each PEG derivative is less than 0.5 kDa.

In certain other embodiments of this aspect of the invention, Fc- specific PEGylated antibody signal-generating moiety conjugates of the present invention comprise one or more signal generating moieties that are thiol reactive signal-generating moieties covalently bound to a thiol group formed on the antibody, wherein each of the one or more thiol reactive signal-generating moieties comprises a discrete linker. In more specific embodiments, the linker is a PEG linker that has a chain length selected from the group consisting of about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , or 12 monomeric PEG units.

In other particular embodiments, Fc-specific PEGylated antibody signal-generating moiety conjugates of the present invention comprise a signal- generating moiety selected from the group consisting of: fluorescent labels, enzyme labels, radioisotopes, chemiluminescent labels, electrochemiluminescent labels, bioluminescent labels, polymers, polymer particles, quantum dots, metal particles, haptens, and dyes. In other particular embodiments, the signal generating moiety comprises an enzymatic label. In more specific embodiments, the enzymatic label is horseradish peroxidase or alkaline phosphatase. In other specific embodiments, the signal generating moiety comprises a hapten, such as biotin.

In still other embodiments, Fc-specific PEGylated antibody signal- generating moiety conjugates of the present invention comprise an antibody that is a monoclonal antibody or a polyclonal antibody.

According to another aspect of the present invention, there is provided a method for preparing an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate, comprising reacting an antibody with an oxidant to form reactive aldehyde groups in a glycosylated region of the Fc- portion of the antibody; reacting the aldehyde group-bearing antibody with a nucleophilic derivative of a hydrophilic, non-immunogenic polymer to form an antibody-polymer intermediate; stabilizing the antibody- polymer intermediate to form an Fc-specific polymer conjugated antibody; forming a thiolated Fc- specific polymer conjugated antibody; forming a thiol reactive signal-generating moiety; and reacting the thiolated Fc-specific polymer conjugated antibody of step (d) with the thiol reactive signal-generating moiety; thereby forming an Fc- specific polymer conjugated antibody signal-generating moiety conjugate. The above steps of this and other synthetic methods herein can be performed in the order noted or in alternative orders. In certain embodiments of this aspect of the invention, the conjugate comprises one or more derivatives of hydrophilic, non-immunogenic polymers each comprising homopolymers selected from the group consisting of: polyvinyl alcohol) (PVA), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone), and polyethylene glycol (PEG). In still other embodiments of this aspect of the invention, the conjugate comprises one or more derivatives of hydrophilic, non-immunogenic polymers each comprising heteropolymers comprising at least one monomeric subunit from two or more of the polymers selected from the group consisting of: polyvinyl alcohol) (PVA), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone), and polyethylene glycol (PEG).

In a particular embodiment of the invention, the hydrophilic, non- immunogenic polymer comprises a polyalkylene glycol. In a more specific embodiment, the hydrophilic, non-immunogenic polymer comprises PEG. In certain other embodiments of this aspect of the invention, the molecular weight of each of the polymers is less than 2 kDa. In certain other embodiments, the molecular weight of each of the polymers is less than 1.5 kDa. In further embodiments, the molecular weight of each of the polymers is less than 1 kDa. In still further embodiments, the molecular weight of each of the polymers is less than 0.5 kDa.

In a more specific embodiment of this aspect of the invention, a method is provided for preparing an Fc-specific PEGylated antibody signal- generating moiety conjugate, comprising: (i) reacting an antibody with an oxidant to form reactive aldehyde groups in a glycosylated region of the Fc- portion of the antibody; (ii) reacting the aldehyde group bearing antibody with a nucleophilic PEG derivative to form an antibody-PEG intermediate; (iii) stabilizing the antibody-PEG intermediate to form an Fc-specific PEGylated antibody; (iv) forming a thiolated Fc-specific PEGylated antibody; (v) forming a thiol reactive signal-generating moiety; and (vi) reacting the thiolated Fc-specific PEGylated antibody of step (iv) with the thiol reactive signal-generating moiety of step (v); thereby forming an Fc-specific PEGylated antibody signal- generating moiety conjugate.

The oxidant(s) used in the methods of the invention may be selected from essentially any suitable oxidants known to the skilled artisan. In certain illustrative embodiments, the oxidant is selected from, but is not limited to, periodates, galactose oxidase, or a combination thereof. In a more specific embodiment, the oxidant is sodium periodate.

The extent of desired oxidation can vary but, in certain embodiments, oxidation of the glycosylated region of the Fc portion of the antibody forms about 1 to 10 aldehyde groups. In certain other embodiments, oxidation of the glycosylated region of the Fc portion of the antibody forms about 4 to 7 aldehyde groups. In certain particular embodiments, about 3 to 5 aldehyde groups are formed by oxidizing the glycosylated region of the Fc portion of the antibody. In more specific embodiments of this aspect of the invention, a method of preparing an Fc-specific PEGylated antibody signal-generating moiety conjugate of the present invention comprises reacting one or more PEG derivatives with the aldehyde groups formed in the glycosylated region of the Fc portion of an antibody, said PEG derivatives having the formula: Y-A-PEG_m-B- X, wherein Y comprises a nucleophilic group selected from the group consisting of: an amino group, a hydrazide group, a carbohydrazide group, a semicarbazide group, a thiosemicarbazide group, a thiocarbazide group, a carbonic acid dihydrazine group, and a hydrazine carboxylate group; wherein X comprises -CH2CH2OCH3 or -CH2CH20H; wherein the subscript m = 1 to 50; and wherein A and B each independently comprise from about 0 to 10 carbon atoms.

In more particular embodiments, a method of preparing an Fc- specific PEGylated antibody signal-generating moiety conjugate of the present invention comprises reacting one or more PEG derivatives with the aldehyde groups formed in the glycosylated region of the Fc portion of an antibody, said PEG derivatives having the formula: Y-A-PEG_m-B-X, wherein the molecular weight of the PEG polymer (e.g., PEG_m) of each PEG derivative is less than about 2 kDa. In other related embodiments, the molecular weight of the PEG polymer of each PEG derivative is less than about 1.5 kDa. In still other related embodiments, the molecular weight of the PEG polymer of each PEG derivative is less than about 1 kDa. In further related embodiments, the molecular weight of the PEG polymer of each PEG derivative is less than about 0.5 kDa.

In other related embodiments of the invention, a method of preparing an Fc-specific PEGylated antibody signal-generating moiety conjugate of the present invention comprises reacting one or more thiol reactive signal generating moieties, wherein each of the one or more thiol reactive signal-generating moieties comprises a discrete linker that has a suitable chain length, e.g., a PEG linker having about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, or more, monomeric PEG units.

In still other particular embodiments, a method of preparing an Fc- specific PEGylated antibody signal-generating moiety conjugate of the present invention comprises a step of stabilizing the antibody-PEG intermediate, for example, by reacting the antibody-PEG intermediate with a reducing agent. Reacting the antibody-PEG intermediate with a reducing agent results in reductive amination of the antibody-PEG intermediate. Suitable agents for effecting reductive amination are known in the art and may be accomplished, for example, by treating the antibody-PEG intermediate with sodium cyanoborohydride, sodium triacetoxyborohydride, an amine borane, or the like.

In other embodiments, a method of preparing an Fc-specific PEGylated antibody signal-generating moiety conjugate of the present invention comprises a step of forming a thiolated Fc-specific PEGylated antibody by reacting an Fc-specific PEGylated antibody with a reducing agent to form thiol groups on the Fc-specific PEGylated antibody. In certain embodiments, the average number of thiol groups per Fc-specific PEGylated antibody is between about 1 and about 10. In certain illustrative embodiments, the reducing agent is selected from, for example, 2-mercaptoethanol, 2-mercaptoethylamine, DTT, DTE and TCEP, and combinations thereof. In more specific embodiments, the reducing agent is selected from the group consisting of DTT and DTE, and combinations thereof. In another specific embodiment, the reducing agent is reacted at a concentration of between about 1 mM and about 40 mM.

In still other embodiments, forming a thiolated Fc-specific PEGylated antibody comprises introducing a thiol group to an Fc-specific PEGylated antibody, for example by reacting the Fc-specific PEGylated antibody with a reagent selected from the group consisting of: 2-lminothiolane, SATA, SATP, SPDP, N-Acetylhomocysteinethiolactone, SAMSA, and cystamine, and combinations thereof. In other particular embodiments, a method of preparing an Fc- specific PEGylated antibody signal-generating moiety conjugate of the present invention comprises forming a thiol reactive signal-generating moiety by reacting a signal generating moiety with a maleimide ester, wherein the maleimide ester comprises an amine-reactive ester group and a thiol-reactive maleimide group, and wherein the maleimide and ester groups are linked by a heterobifunctional polyalkylene glycol linker. In related particular embodiments, the polyalkylene glycol linker is a discrete PEG. In certain particular embodiments, the discrete PEG has a chain length selected from the group consisting of about 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , or 12, or more PEG units. In still other embodiments, a method of preparing an Fc-specific

PEGylated antibody signal-generating moiety conjugate of the present invention employs a signal-generating moiety selected from the group consisting of: fluorescent labels, enzyme labels, radioisotopes, chemiluminescent labels, electrochemiluminescent labels, bioluminescent labels, polymers, polymer particles, quantum dots, metal particles, haptens, and dyes. In more specific embodiments, the enzymatic label is horseradish peroxidase or alkaline phosphatase. In another specific embodiment, the signal generating moiety comprises a hapten, such as biotin.

In still other embodiments, a method of preparing an Fc-specific PEGylated antibody signal-generating moiety conjugate of the present invention comprises an antibody that is a monoclonal or polyclonal antibody. According to another aspect of the present invention, there is provided a method for detecting a molecule of interest in a biological sample comprising contacting the biological sample with an Fc-specific polymer- conjugated antibody signal-generating moiety conjugate, as described herein, that binds to the molecule of interest and detecting a signal generated by the Fc-specific polymer-conjugated antibody signal-generating moiety conjugate that indicates the presence of the molecule of interest in the sample.

In another aspect, the present invention provides a method for detecting a molecule of interest in a biological sample comprising: (i) contacting the biological sample with a primary antibody that binds to the molecule of interest; (ii) contacting the sample of step (i) with an Fc-specific polymer conjugated antibody signal-generating moiety conjugate, as described herein, that binds to the primary antibody; and (iii) detecting a signal generated by the Fc-specific polymer conjugated antibody signal-generating moiety conjugate that indicates the presence of the molecule of interest in the sample, wherein said polymer is hydrophilic and non-immunogenic.

In another aspect, the present invention provides a method for detecting a molecule of interest in a biological sample, comprising: (i) contacting the biological sample with a labeled nucleic acid probe that binds to the molecule of interest; (ii) contacting the sample of step (i) with an Fc-specific polymer conjugated antibody signal-generating moiety conjugate, as described herein, that binds to the labeled nucleic acid probe; and (iii) detecting a signal generated by the Fc-specific polymer conjugated antibody signal-generating moiety conjugate that indicates the presence of the molecule of interest in the sample, wherein said polymer is hydrophilic and non-immunogenic.

In certain embodiments of the above detection methods, a biological sample comprises a urine, blood, sera, sputum, tissue, or cellular sample.

In other embodiments, the detection method comprises an in situ hybridization (ISH), immunohistochemistry (IHC), immunocytochemistry (ICC), flow cytometry, enzyme immuno-assay (EIA), or enzyme linked immuno-assay (ELISA) method.

According to another aspect, the present invention also provides kits for detecting a molecule of interest in a biological sample, comprising an Fc-specific polymer conjugated antibody signal-generating moiety conjugate, as described herein. The kits may comprise any of a number of signal-generating moiety, e.g., selected from the group consisting of: fluorescent labels, enzyme labels, radioisotopes, chemiluminescent labels, electrochemiluminescent labels, bioluminescent labels, polymers, polymer particles, quantum dots, metal particles, haptens (e.g., biotin), and dyes. The kits may also comprise, in certain specific embodiments, streptavidin-HRP, avidin-HRP, streptavidin-AP, avidin-AP, streptavidin-colloidal gold, and/or avidin-colloidal gold.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows the results of an HRP-DAB staining for anti-Ki-67 antibody detection in tonsil sections with Fc-specific PEGylated conjugates (FIG. 1A) and non-PEGylated antibody conjugates (FIG. 1 B) (e.g., control conjugates).

FIG. 2 shows the results of an HRP-DAB staining for anti-CD15 antibody detection in Hodgkin's Lymphoma sections with Fc-specific PEGyiated conjugates (FIG. 2A) and non-PEGylated antibody conjugates (FIG. 2B) (e.g., control conjugates).

FIG. 3 shows the results of an HRP-DAB staining for anti-CD20 antibody detection in tonsil sections with Fc-specific PEGylated conjugates (FIG. 3A) and non-PEGylated antibody conjugates (FIG. 3B) (e.g., control conjugates).

FIG. 4 shows the results of HRP-DAB staining for anti-CD15 antibody in tonsil sections with a cocktail of Fc-specific PEGylated conjugates (FIGs. 4A and 4B) and non-PEGylated antibody conjugates (FIGs. 4C and 4D) (e.g., control conjugates). Primary antibody application was omitted from the experiments shown in FIGs. 4A and 4C to examine background staining of the conjugates.

FIG. 5 shows the results of HRP-DAB staining for anti-CD57 antibody in tonsil sections with a cocktail of Fc-specific PEGylated conjugates (FIGs. 5A and 5B) and non-PEGylated antibody conjugates (FIGs. 5C and 5D) (e.g., control conjugates). Primary antibody application was omitted from the experiments shown in FIGs. 5A and 5C to examine background staining of the conjugates.

FIG. 6 shows the results of HRP-DAB staining for anti-Her2-neu antibody in breast tissue sections with a cocktail of Fc-specific PEGylated conjugates (FIGs. 6A and 6B) and non-PEGylated antibody conjugates (FIGs. 6C and 6D) (e.g., control conjugates). Primary antibody application was omitted from the experiments shown in FIGs. 6A and 6C to examine background staining of the conjugates. FIG. 7 shows the results of HRP-DAB staining for anti-Ki-67 antibody in tonsil sections with a cocktail of Fc-specific PEGylated conjugates (FIGs. 7A and 7B) and non-PEGylated antibody conjugates (FIGs. 7C and 7D) (e.g., control conjugates). Primary antibody application was omitted from the experiments shown in FIGs. 7A and 7C to examine background staining of the conjugates.

FIG. 8 shows the results of HRP-DAB staining for anti-PR (progesterone receptor) antibody in breast tissue sections with a cocktail of Fc- specific PEGylated conjugates (FIGs. 8A and 8B) and non-PEGylated antibody conjugates (FIGs. 8C and 8D) (e.g., control conjugates). Primary antibody application was omitted from the experiments shown in FIGs. 8A and 8C to examine background staining of the conjugates.

DETAILED DESCRIPTION

In general, the compounds used in the reactions described herein may be made according to organic synthesis techniques known to those skilled in this art, starting from commercially available chemicals and/or from compounds described in the chemical literature. "Commercially available chemicals" may be obtained from standard commercial sources including, but not limited to Quanta Biodesign (Powell, OH), Iris Biotech (GmbH), Nanocs, Inc. (Ney York, NY), Nektar (San Carlos, CA), Acros Organics (Pittsburgh PA), Aldrich Chemical (Milwaukee Wl, including Sigma Chemical and Fluka), Apin Chemicals Ltd. (Milton Park UK), Avocado Research (Lancashire U.K.), BDH Inc. (Toronto, Canada), Bionet (Cornwall, U.K.), Chemservice Inc. (West Chester PA), Crescent Chemical Co. (Hauppauge NY), Eastman Organic Chemicals, Eastman Kodak Company (Rochester NY), Fisher Scientific Co. (Pittsburgh PA), Fisons Chemicals (Leicestershire UK), Frontier Scientific (Logan UT), ICN Biomedicals, Inc. (Costa Mesa CA), Key Organics (Cornwall U.K.), Lancaster Synthesis (Windham NH), Maybridge Chemical Co. Ltd. (Cornwall U.K.), Parish Chemica I Co. (Orem UT), Pfaltz & Bauer, Inc. (Waterbury CN), Polyorganix (Houston TX), Pierce Chemical Co. (Rockford IL), Riedel de Haen AG (Hanover, Germany), Spectrum Quality Product, Inc. (New Brunswick, NJ), TCI America (Portland OR), Trans World Chemicals, Inc. (Rockville MD), and Wako Chemicals USA, Inc. (Richmond VA).

Methods known to one of ordinary skill in the art may be identified through various reference books and databases. Suitable reference books and treatises that detail the synthesis of reactants useful in the preparation of compounds and compound conjugates described herein, or provide references to articles that describe the preparation, include for example, "Synthetic Organic Chemistry," John Wiley & Sons, Inc., New York; S. R. Sandler et al., "Organic Functional Group Preparations, " 2nd Ed., Academic Press, New York, 1983; H. O. House, "Modern Synthetic Reactions, " 2nd Ed., W. A. Benjamin, Inc. Menlo Park, Calif. 1972; T. L. Gilchrist, "Heterocyclic Chemistry", 2nd Ed., John Wiley & Sons, New York, 1992; J. March, "Advanced Organic Chemistry: Reactions, Mechanisms and Structure", 4th Ed., Wiley-lnterscience, New York, 1992. Additional suitable reference books and treatises that detail the synthesis of reactants useful in the preparation of conjugate compounds described herein, or provide references to articles that describe the preparation, include for example, Fuhrhop, J. and Penzlin G. Organic Synthesis: Concepts, Methods, Starting Materials", Second, Revised and Enlarged Edition (1994) John Wiley & Sons ISBN: 3-527-29074-5; Hoffman, R.V. "Organic Chemistry, An Intermediate Text" (1996) Oxford University Press, ISBN 0-19-509618-5; Larock, R. C. "Comprehensive Organic Transformations: A Guide to Functional Group Preparations" 2nd Edition (1999) Wiley-VCH, ISBN: 0-471-19031-4; March, J. "Advanced Organic Chemistry: Reactions, Mechanisms, and Structure" 4th Edition (1992) John Wiley & Sons, ISBN: 0-471-60180-2; Otera, J. (editor) "Modern Carbonyl Chemistry" (2000) Wiley-VCH, ISBN: 3-527- 29871-1 ; Patai, S. "Patai's 1992 Guide to the Chemistry of Functional Groups" (1992) lnterscience ISBN: 0-471-93022-9; Quin, L.D. et al. "A Guide to Organophosphorus Chemistry" (2000) Wiley-lnterscience, ISBN: 0-471-31824- 8; Solomons, T. W. G. "Organic Chemistry" 7th Edition (2000) John Wiley & Sons, ISBN: 0-471-19095-0; Stowell, J.C., "Intermediate Organic Chemistry" 2nd Edition (1993) Wiley-lnterscience, ISBN: 0-471-57456-2; "Industrial Organic Chemicals: Starting Materials and Intermediates: An Ullmann's Encyclopedia" (1999) John Wiley & Sons, ISBN: 3-527-29645-X, in 8 volumes; "Organic Reactions" (1942-2000) John Wiley & Sons, in over 55 volumes; and "Chemistry of Functional Groups " John Wiley & Sons, in 73 volumes. Specific and analogous reactants may also be identified through the indices of known chemicals prepared by the Chemical Abstract Service of the American Chemical Society, which are available in most public and university libraries, as well as through on-line databases (the American Chemical Society, Washington, D. C, may be contacted for more details). Chemicals that are known but not commercially available in catalogs may be prepared by custom chemical synthesis houses, where many of the standard chemical supply houses (e.g., those listed above) provide custom synthesis services.

In addition, related U.S. Patent Application Publication Nos. 2007/0117153 and 2006/0246523, are specifically incorporated herein by reference in their entireties. These co-owned applications describe a variety of conjugation chemistries, linking techniques and antibody conjugates that would be understood by the skilled artisan as applicable in the context of the present invention.

1. Fc-specific Polymer-Conjugated Antibodies The present invention provides, in part, compositions comprising hydrophilic, non-immunogenic polymers conjugated to antibodies, and methods of making and using such antibodies. More specifically, the present invention provides Fc-specific polymer-conjugated antibodies, wherein hydrophilic, non- immunogenic polymers are covalently bound to oligosaccharide moieties of the glycosylated Fc portion of the antibodies. Without wishing to be bound by any particular theory, it is believed that site-specific conjugation of small hydrophilic, non immunogenic polymers (e.g., PEG) at glycosylation sites within the Fc region of antibodies effectively reduces the overall background staining of the antibodies by masking them from the native immune system's cells and/or proteins, which mainly involve the Fc region, e.g., native Fc receptors.

Accordingly, the Fc-specific polymer-conjugated antibodies of the invention can be advantageously used in any of a number of diagnostic settings and exhibit superior performance for detection of molecules of interest in biological samples, especially for detection of such molecules in tissue sections and/or cytology samples.

As used herein, the term 'Fc-specific polymer-conjugated antibody' refers to an immunoglobulin (or fragment thereof) in which a hydrophilic, non-immunogenic polymer or derivative thereof is covalently bound to the glycosylated portion of the immunoglobulin (or a fragment of an immunoglobulin that retains the glycosylated portion). The term 'Fc-specific PEGylated-antibody' refers to an immunoglobulin (or fragment thereof) in which a PEG molecule or derivative is covalently bound to the glycosylated portion of the immunoglobulin (or a fragment of an immunoglobulin that retains the glycosylated portion). The glycosylated portion of an immunoglobulin is found in the Fc-region, which is a region of an immunoglobulin that is located on the heavy chains of the immunoglobulin at positions outside of the portion of the immunoglobulin that is responsible for the specific binding activity of the immunoglobulin.

According to certain aspects of the present invention, a hydrophilic, non-immunogenic polymer as described herein is attached to an Fc region oligosaccharide of the antibody as a substantially discrete molecule and is not used as a linker for further conjugation to another molecule or moiety, such as a signal-generating moiety.

Exemplary hydrophilic, non-immunogenic polymers suitable for antibody conjugation in an Fc-specific manner according to the invention can include hydrophilic, non-immunogenic homopolymers and/or heteropolymers. The terms heteropolymer or copolymer refer to a polymer derived from two (or more) different monomeric unit types, as opposed to a homopolymer where only one monomer unit type is present in the polymer. Suitable heteropolymers can include block copolymers, e.g., a heteropolymer comprising two or more homopolymer subunits linked by covalent bonds. The union of the homopolymer subunits may require an intermediate non-repeating subunit, known as a junction block. Block copolymers with two or three distinct blocks are called diblock copolymers and triblock copolymers, respectively. Any such polymer types may be used in accordance with the present invention provided they do not adversely compromise the intended function or specificity of the antibody being modified and provided they meet at least one of the advantages and/or objectives described herein (e.g., reduced background staining relative to a corresponding antibody that is not polymer-conjugated in the Fc region). In certain illustrative embodiments, the hydrophilic, non-immunogenic polymer comprises a polyalkylene glycol. In other illustrative embodiments, the hydrophilic, non-immunogenic polymer comprises polyvinyl alcohol) (PVA), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone), and/or polyethylene glycol (PEG). In certain embodiments the hydrophilic, non-immunogenic polymer is a homopolymer and the number of monomeric units in the homopolymer range from about 1 to 50, 2 to 30, 3 to 20, or 4 to 12. In other embodiments, the number of monomeric units in the hydrophilic, non- immunogenic homopolymer is about 1 , 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 PEG monomer units. In certain other embodiments, the homopolymers are of varied lengths in the range of about 1 to 50, about 10 to 40, or about 20 to 30 monomer units.

In certain preferred embodiments, the number of homopolymer monomer units is such that molecular weight of the homopolymer itself is less than 2 kDa, less than 1.5 kDa, less than 1 kDa, or less than 500 Da. In more particular embodiments, the molecular weight of the homopolymer is about 2 kDa, about 1.8 kDa, about 1.8 kDa, about 1.5 kDa, about 1.2 kDa, about 1.0 kDa, about 0.8 kDa, about 0.7 kDa, about 0.6 kDa, about 0.5 kDa, or about 0.2 kDa. In certain embodiments, the homopolymers are of varied molecular weights in the range of about 2 kDa to 0.5 kDa, about 1.5 kDa, to 0.5 kDa, about 1.0 kDa to 0.5 kDa, or about 0.5 kDa to 0.1 kDa.

In other embodiments, the polymer is a hydrophilic, non- immunogenic heteropolymer that comprises at least one monomeric unit from two or more of the following polymers selected from the group consisting of polyvinyl alcohol) (PVA), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone), and polyethylene glycol.

In certain embodiments, the heteropolymer is a block copolymer comprising one or more monomeric units of a PEG polymer, and at least one monomeric unit of one or more polymers selected from the group consisting of polyvinyl alcohol) (PVA), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), and polyvinyl pyrrolidinone).

The number of monomeric units in the hydrophilic, non- immunogenic heteropolymer can vary but, in many embodiments, will range from about 1 to 50, 2 to 30, 3 to 20, or 4 to 12. In certain embodiments, the number of monomeric units in the hydrophilic, non-immunogenic heteropolymer is 1 , 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 PEG monomer units. In certain other embodiments, the heteropolymers of are of varied lengths in the range of about 1 to 50, about 10 to 40, or about 20 to 30 monomer units.

In certain preferred embodiments, the number of heteropolymer monomer units is such that molecular weight of the heteropolymer itself is less than about 2 kDa, less than 1.5 kDa, less than 1 kDa, or less than 500 Da. In more particular embodiments, the molecular weight of the heteropolymer is about 2 kDa, about 1.8 kDa, about 1.8 kDa, about 1.5 kDa, about 1.2 kDa, about 1.0 kDa, about 0.8 kDa, about 0.7 kDa, about 0.6 kDa, about 0.5 kDa, or about 0.2 kDa. In other embodiments, the heteropolymers are of varied molecular weights in the range of about 2 kDa to 0.5 kDa, about 1.5 kDa, to 0.5 kDa, about 1.0 kDa to 0.5 kDa, or about 0.5 kDa to 0.1 kDa.

One having ordinary skill in the art would recognize that any combination of homopolymers and heterpolymers as described herein are suitable for conjugation to the same antibody, wherein the polymers are hydrophilic and non-immunogenic.

The present invention further provides a method for preparing an Fc-specific polymer-conjugated antibody that comprises: i) reacting an antibody with an oxidant to form reactive aldehyde groups in the Fc-portion of the antibody; ii) reacting the aldehyde-bearing antibody with a hydrophilic, non- immunogenic polymer or derivative to form an antibody-polymer intermediate; and iii) stabilizing the antibody-polymer intermediate to form an Fc-specific polymer-conjugated antibody.

One particularly preferred hydrophilic, non-immunogenic polymer is PEG. Thus, the present invention further provides a method for preparing an Fc-specific PEGylated antibody that comprises conjugating a PEG derivative to an oligosaccharide moiety of the glycosylated region of an antibody (e.g., the Fc portion of the antibody).

In other embodiments , the present invention provides a method for preparing an Fc-specific polymer-conjugated antibody that comprises: i) reacting an antibody with an oxidant to form reactive aldehyde groups in the Fc- portion of the antibody; ii) reacting the aldehyde-bearing antibody with a nucleophilic hydrophilic, non-immunogenic polymer derivative to form an antibody-polymer intermediate; and iii) stabilizing the antibody-polymer intermediate to form an Fc-specific polymer-conjugated antibody.

In a particular embodiment, reacting the antibody with an oxidant to form the aldehyde-bearing antibody includes oxidizing (e.g., by treating with sodium periodate or galactose oxidase) vicinal diols of carbohydrates within a glycosylated region of the antibody to form reactive aldehyde groups in the Fc- portion of the antibody.

Modification of periodate-oxidized antibodies does not typically inactivate the antibody. Varying the concentration of sodium periodate during the oxidation reaction gives some specificity with regard to the types of sugar residues that are modified. For example, sodium periodate at a concentration of 1 mM at O⁰C typically cleaves only at the adjacent hydroxyls between carbon atoms 7, 8 and 9 of sialic acid residues. Oxidizing polysaccharides using 10 mM or greater concentrations of sodium periodate results in oxidation of sugar residues other than sialic acid, thereby creating many aldehydes on a given polysaccharide. A suitable general protocol is described by Hermanson, "Bioconjugate Techniques," Academic Press, San Diego, 1996, ISBN 0-12- 342336-8, which is incorporated by reference herein. Illustrative examples of periodate concentrations suitable for oxidizing antibodies of the present invention are between 1 mM and 5OmM, between 1 mM and 25 mM, between 1 mM and 20 mM, between 1 mM and 10 mM, or any intervening concentration. For example, periodate can be used to introduce aldehyde groups in an antibody of the present invention at a concentration of about 1 mM, about 2 mM, about 5 mM, about 10 mM, about 15 mM, about 20 mM, about 25 mM, about 30 mM, about 35 mM, about 40 mM, about 45 mM, about 50 mM, or any intervening concentration.

Another method for introducing aldehydes into biomolecules is through the use of specific sugar oxidases, for example, galactose oxidase, which is an enzyme that oxidizes terminal galactose residues to aldehydes, particularly in glycoproteins. When galactose residues are penultimate to sialic acid residues, neuramidase can be used to remove the sialic acid residue and expose galactose as the terminal residue. A protocol for using a combination of neuramidase and galactose oxidase to oxidize galactose residues to provide a reactive aldehyde group is provided in Hermanson, "Bioconjugate Techniques," Academic Press, San Diego, 1996, ISBN 0-12-342336-8, which is incorporated by reference herein. Aldehydes also can be introduced to a molecule by reacting an amine group of a molecule with an NHS-aldehyde such as succinimidyl p-formylbenzoate (SFB) or succinimidyl p-formylphenoxyacetate (SFPA) (Invitrogen Corp., Eugene, OR). Alternatively, bis-aldehyde compounds such as glutaraldehyde can be used to modify an amine group to provide an aldehyde group. Again, suitable protocols are provided in Hermanson, "Bioconjugate Techniques," Academic Press, San Diego, 1996, ISBN 0-12-342336-8, which is incorporated by reference herein.

In addition, double bonds in unsaturated fatty acids and ceramides can be converted to diols by osmium tetroxide and then oxidized by periodate to aldehydes. Furthermore, N-terminal serine and threonine residues of peptides and proteins can be selectively oxidized by periodate to aldehyde groups, permitting selective modification of certain proteins such as corticotrophin and β-lactamase. In a particular embodiment, reacting an antibody with an oxidant to form reactive aldehyde groups in the Fc-portion of the antibody includes introducing an average of between about 1 and about 10 aldehyde groups per antibody, between about 2 and about 9 aldehyde groups per antibody, between about 3 and about 8 aldehyde groups per antibody, between about 4 and about 7 aldehyde groups per antibody, between about 3 and about 5 aldehyde groups per antibody, or between about 4 and about 6 aldehyde groups per antibody. In another particular embodiment, reacting an antibody with an oxidant to form reactive aldehyde groups in the Fc-portion of the antibody includes introducing at least 1 , at least 2, at least 3, at least 4, at least 5, or at least 6 or more aldehyde groups per antibody. In a more particular embodiment, reacting an antibody with an oxidant to form reactive aldehyde groups in the Fc-portion of the antibody includes introducing 1 , 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more aldehyde groups.

In another particular embodiment, a method of preparing an Fc- specific polymer-conjugated antibody comprises reacting the aldehyde-bearing antibody with a hydrophilic, non-immunogenic, nucleophilic polymer derivative (e.g., a nucleophilic PEG derivative). As used herein, the term "nucleophilic polymer derivative" refers to a polymer chain comprising a terminal amino group or hydrazide group (-CO-NH-NH2); a carbohydrazide group (-NH-NH- CO-NH-NH2); a semicarbazide group (-NH-CO-NH-NH2); a thiosemicarbazide group (-NH-CS-NH-NH2); a thiocarbazide group (-NH-NH-CS-NH-NH2); a carbonic acid dihydrazine group (-NH-CO-NH-NH-CO-NH-NH2) or a sulfur containing derivative thereof; or a hydrazine carboxylate group (-O-CO-NH- NH2) or a sulfur-containing derivative thereof, and the like.

In preferred embodiments, the nucleophilic polymer derivative comprises a terminal amino or hydrazide group. As noted above, a group of atoms that can react with and form a covalent bond to an amino group or a hydrazide group, include aldehyde and ketone groups. These aldehyde and ketone groups can be an intrinsic part of a molecule or can be introduced to a molecule. In certain embodiments, a method of preparing an Fc-specific polymer-conjugated antibody comprises reacting an aldehyde-bearing antibody with a nucleophilic PEG derivative to form an antibody-PEG intermediate, wherein the nucleophilic PEG derivative has the general formula:

Y-A-PEG_m-B-X

wherein Y represents a nucleophilic group, including, but not limited to an amino group (e.g., NH₂-) or hydrazide group (e.g., NH₂NHCO-); wherein X represents -CH₂CH₂OCH₃ or -CH₂CH₂OH, and wherein the subscript m represents the number of CH₂CH₂O monomer units (e.g., ethylene glycols) in the PEG chain, e.g., PEG_m=5o refers to a PEG polymer having 50 CH₂CH₂O monomer units or ethylene glycols. In particular embodiments m = 1 to 50, 2 to 30, 3 to 20, or 4 to 12. In certain embodiments, m = 1 , 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 PEG monomer units. In certain particular embodiments, the nucleophilic PEG derivatives reacted with the aldehyde bearing antibodies are of varied lengths in the range of about 1 to 50, about 10 to 40, or about 20 to 30 PEG monomer units.

In preferred embodiments, the number of PEG monomer units is such that molecular weight of the PEG polymer itself is less than 2 kDa, less than 1.5 kDa, less than 1 kDa, or less than 500 Da. In more particular embodiments, the molecular weight of the PEG polymer is about 2 kDa, about 1.8 kDa, about 1.8 kDa, about 1.5 kDa, about 1.2 kDa, about 1.0 kDa, about 0.8 kDa, about 0.7 kDa, about 0.6 kDa, about 0.5 kDa, or about 0.2 kDa. In certain embodiments, the nucleophilic PEG derivatives reacted with the aldehyde bearing antibodies are of varied molecular weights in the range of about 2 kDa to 0.5 kDa, about 1.5 kDa, to 0.5 kDa, about 1.0 kDa to 0.5 kDa, or about 0.5 kDa to 0.1 kDa.

In certain embodiments, X and/or Y can be separated from the PEG chain by spacer groups A and B. For example, spacer groups having between 0 and 10 carbons such as between 1 and 10 carbons, between 1 and 6 carbons or between 1 and 4 carbons, and optionally containing one or more amide linkages, ether linkages, ester linkages, and the like. Spacers groups between X and/or Y and the PEG chain can be the same or different, and can be straight-chained, branched or cyclic (for example, aliphatic or aromatic cyclic structures), and can be unsubstituted or substituted. Functional groups that can be substituents on a spacer include carbonyl groups, hydroxyl groups, halogen (F, Cl, Br and I) atoms, alkoxy groups (such as methoxy and ethoxy), nitro groups, and sulfato groups.

In another particular embodiment, a method of preparing an Fc- specific polymer-conjugated antibody further comprises stabilizing the antibody- polymer intermediate through a reductive amination reaction to form an Fc- specific polymer-conjugated antibody. As used herein, the term "amination" refers to reaction of a carbonyl group of an aldehyde or a ketone with an amine group, wherein an amine-containing compound such as an amine reacts with the aldehyde or ketone to first form a Schiff base that can then reversibly rearrange to a more stable form, or optionally be reduced to prevent reversal of the reaction. As used herein, the term "reductive amination" refers to an amination reaction that proceeds with the addition of a reducing agent, more typically addition of a mild reducing agent such as sodium cyanoborohydride or one of its cogeners (or congeners), for example, sodium triacetoxyborohydride. Other mild reducing agents that can be employed include various amine boranes. In certain embodiments, wherein the nucleophilic polymer derivative is a hydrazide-polymer derivative, reacting the aldehyde-bearing antibody with the hydrazide- polymer derivative forms a hydrazone bond between the antibody and the polymer derivative. This bond can be stabilized by reduction with a suitable reducing agent, including, but not limited to sodium cyanoborohydride. In other certain embodiments, wherein the polymer derivative is an amine- polymer derivative, reacting the aldehyde-bearing antibody with the amine- polymer derivative forms a reversible Schiff base bond between the antibody and the polymer derivative. This Schiff base linkage can also be stabilized by reduction with a suitable reducing agent, including, but not limited to sodium cyanoborohydride.

One having ordinary skill in the arts would understand that the Fc portion of an antibody can be polymer-conjugated with a single nucleophilic- polymer derivative (e.g., amino-PEG derivative) or with multiple nucleophilic polymer derivatives. For example, in some embodiments, it is preferred to conjugate 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more nucleophilic- polymer derivatives (e.g., amino-PEG derivatives) to available aldehyde groups on the Fc portion of the antibody. H. Fc-specific Polymer-Conjugated Antibody Signal-generating Moiety Conjugates

The Fc-specific polymer-conjugated antibodies of the invention may further comprise one or more signal-generating moieties, thereby providing Fc-specific polymer-conjugated antibody signal-generating moiety conjugates. Thus, in another aspect, the present invention provides Fc-specific polymer- conjugated antibody signal-generating moiety conjugates and methods of making and using such conjugates.

As used herein, the term "conjugate" refers to two or more molecules (and/or materials such as nanoparticles) that are covalently linked into a larger construct. In some embodiments, a conjugate comprises one or more biomolecules (such as peptides, antibodies, nucleic acids, proteins, enzymes, sugars, polysaccharides, lipids, glycoproteins, biopolymers (e.g., PEG), and lipoproteins) covalently linked to one or more other molecules, such as one or more other biomolecules. In other embodiments, a conjugate includes one or more specific-binding molecules (such as antibodies and/or nucleic acid sequences) covalently linked to one or more detectable labels (such as fluorescent molecules, fluorescent nanoparticles, haptens, enzymes and combinations thereof). As used herein, the terms "Fc-specific polymer-conjugated antibody signal-generating conjugate" and "Fc-specific polymer-conjugated antibody signal-generating moiety conjugate" refer to a conjugate of an Fc- specific polymer-conjugated antibody, as described herein, further comprising signal-generating moieties covalently bound to the antibody. Signal-generating moieties may be attached to the Fc-specific polymer-conjugated antibody at essentially any suitable site. In one illustrative embodiment, the signal-generating moieties are attached via amino acid residues of the antibody, e.g., reactive thiol groups. In other embodiments, the signal-generating moieties may be bound directly to Fc oligosaccharides, or may be bound indirectly to Fc oligosaccharides via linkers (e.g., PEG linkers). Suitable conjugation chemistries in this regard can include, for example, those described in U.S. Patent Application Publication Nos. 2007/0117153 and 2006/0246523, the contents of which are incorporated herein by reference in their entireties.

In one embodiment, a method of preparing an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate comprises covalently conjugating one or more derivatives of hydrophilic, non-immunogenic polymers to oligosaccharide moieties in a glycosylated region of the Fc portion of an antibody; and further covalently conjugating one or more signal- generating moieties to the antibody, particularly via moieties other than said covalently bound polymers.

In a particularly preferred embodiment, a method of preparing an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate comprises covalently conjugating one or more PEG derivatives to oligosaccharide moieties in a glycosylated region of the Fc portion of an antibody; and further covalently conjugating one or more signal-generating moieties to the antibody via moieties other than said covalently bound PEG derivatives.

The one or more signal generating moieties, in certain illustrative embodiments, are thiol reactive signal-generating moieties covalently bound to thiol groups formed on the antibody.

Thus, the invention further provides a method of preparing an Fc- specific polymer-conjugated antibody signal-generating moiety conjugate comprises: i) generating a thiolated Fc-specific polymer-conjugated antibody; ii) synthesizing a thiol reactive signal-generating moiety; and iii) reacting the thiolated Fc-specific polymer-conjugated antibody of step i) with the thiol reactive signal-generating moiety of step ii), thereby forming an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate.

In a particular embodiment, a thiolated antibody (e.g., a thiolated Fc-specific polymer-conjugated antibody) can be formed by reacting the antibody with a reducing agent to form the thiolated antibody. Reacting the antibody with a reducing agent forms a thiolated antibody having an average number of thiols per antibody of between, for example, about 1 to about 10, between about 2 to about 9, between about 3 to about 8, between about 2 to about 6, between about 3 to about 6,or between about 3 to about 5. In certain embodiments, the average number of thiols per antibody is about 1 , about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, or about 10 or more. The average number of thiols per antibody can be determined, for example, by titration. Examples of reducing agents include, but are not limited to, 2-mercaptoethanol, 2-mercaptoethylamine, DTT (dithiothreitol; trans-2,3- dihydroxy-1 ,4-dithiolbutane), DTE (dithioerythritol; cis-2,3-dihydroxy-1 ,4- dithiolbutane), and TCEP(tris(carboxyethyl)phosphine ),and combinations thereof. In a particular embodiment, the reducing agent is DTT and/or DTE, used at a concentration of between about 1 mM and about 40 mM. In more specific embodiments, the concentration of reducing agent is about 5 mM, 10 mM, 15 mM, 20 mM, 25 mM, 30 mM, 35 mM, or 40 mM, or any intermediate concentration of reducing agent.

Alternatively, forming the thiolated Fc-specific polymer-conjugated antibody includes introducing a thiol group to the antibody. For example, the thiol group can be introduced to the antibody by reaction with a reagent such as 2-lminothiolane, SAMSA (S-Acetylmercaptosuccinic acid), SATA (N- succinimidyl S-acetylthioacetate), SATP (Succinimidyl acetyl-thiopropionate), SPDP (N-Succinimidyl 3-(2-pyridyldithio)propionate), N- Acetylhomocysteinethiolactone, and cystamine, and combinations thereof (see, for example, Hermanson, "Bioconjugate Techniques," Academic Press, San Diego, 1996, which is incorporated by reference herein). The generation of thiol reactive signal-generating moieties, is taught, for example in U.S. Patent Application Publication Nos. 2007/0117153 and 2006/0246523, the contents of which are incorporated herein by reference in their entireties.

Illustrative examples of signal-generating moieties include, but are not limited to fluorescent labels, enzyme labels, radioisotopes, chemiluminescent labels, electrochemiluminescent labels, bioluminescent labels, polymers, polymer particles, quantum dots, metal particles, haptens, and dyes.

Illustrative examples of fluorescent signal-generating moieties include quantum dots, 5-(and 6)-carboxyfluorescein, 5- or 6-carboxyfluorescein, 6-(fluorescein)-5-(and 6)-carboxamido hexanoic acid, fluorescein isothiocyanate, rhodamine, tetramethylrhodamine, and dyes such as Cy2, Cy3, and Cy5, optionally substituted coumarin including AMCA, PerCP, phycobiliproteins including R-phycoerythrin (RPE) and allophycoerythrin (APC),

Texas Red, Princeton Red, green fluorescent protein (GFP) and analogues thereof, and conjugates of R-phycoerythrin or allophycoerythrin, inorganic fluorescent labels such as particles based on semiconductor material like coated CdSe nanocrystallites.

Illustrative examples of signal-generating moieties in the class of polymer particles include micro particles or latex particles of polystyrene, PMMA or silica, which can be embedded with fluorescent dyes, or polymer micelles or capsules which contain dyes, enzymes or substrates.

Illustrative examples of signal-generating moieties in the class of metal particles include gold particles and coated gold particles, which can be converted by silver stains. Illustrative examples of signal-generating moieties in the class of haptens include DNP, fluorescein isothiocyanate (FITC), biotin, and digoxigenin.

Illustrative examples of enzymatic signal-generating moieties include horseradish peroxidase (HRP), alkaline phosphatase (ALP or AP), β- galactosidase (GAL), glucose-6-phosphate dehydrogenase, β-N- acetylglucosamimidase, β-glucuronidase, invertase, Xanthine Oxidase, coleopteran luciferases (e.g., firefly, click beetle, etc.) and glucose oxidase

(GO).

Illustrative examples of commonly used substrates for horseradish peroxidase include 3,3'-diaminobenzidine (DAB), diaminobenzidine with nickel enhancement, 3-amino-9-ethylcarbazole (AEC), Benzidine dihydrochioride (BDHC), Hanker-Yates reagent (HYR), lndophane blue (IB), tetramethylbenzidine (TMB), 4-chloro-1-naphtol (CN), . alpha. -naphtol pyronin (.alpha. -NP), o-dianisidine (OD), δ-bromo-Φchloro-S-indolylphosp- hate (BCIP), Nitro blue tetrazolium (NBT), 2-(p-iodophenyl)-3-p-nitropheny- l-5-phenyl tetrazolium chloride (INT), tetranitro blue tetrazolium (TNBT), and 5-bromo-4- chloro-3-indoxyl-beta-D-galactoside/ferro-ferricyanide (BCIG/FF).

Illustrative examples of commonly used substrates for Alkaline Phosphatase include Naphthol-AS-B 1 -phosphate/fast red TR (NABP/FR), Naphthol-AS-MX-phosphate/fast red TR (NAMP/FR), Naphthol-AS-B1- phosphate/- fast red TR (NABP/FR), Naphthol-AS-MX-phosphate/fast red TR (NAMP/FR), Naphthol-AS-B1 -phosphate/new fuschin (NABP/NF), bromochloroindolyl phosphate/nitroblue tetrazolium (BCIP/NBT), and 5-Bromo- 4-chloro-3-indolyl-b" d-galactopyranoside (BCIG).

Illustrative examples of luminescent signal-generating moieties include luminol, luciferin, isoluminol, achdinium esters, 1 ,2-dioxetanes and pyhdopyridazines. Illustrative examples of electrochemiluminescent signal- generating moieties include ruthenium derivatives.

Illustrative examples of radioactive signal-generating moieties include radioactive isotopes of iodide, cobalt, selenium, tritium, carbon, sulfur and phosphorous.

These and other signal-generating moieties are known and established in the art and may be used in the context of the present invention. For example, additional illustrative examples of suitable signal-generating moieties can be found in "The Handbook — A Guide to Fluorescent Probes and Labeling Technologies", Invitrogen Corporation (Eugene, OR).

As noted above, in certain embodiments of the invention, signal- generating moieties can be attached to an Fc-specific polymer-conjugated antibody of the invention directly through unreacted oligosaccharide moieties. For example, after the Fc portion of an antibody has been polymer-conjugated by the methods described herein, unreacted oligosaccharide moieties in the Fc portion of the antibody can be directly conjugated to one or more signal generating moieties. In this context, unreacted refers to the oligosaccharide moieties in the glycosylated region of the antibody (the Fc portion) that have been treated with periodate, but have not been oxidized nor converted to aldehyde groups. Alternatively, or in addition, signal-generating moieties can be attached to Fc oligosaccharides indirectly via linkers. For example, in certain embodiments, an Fc specific PEGylated antibody signal-generating moiety conjugate comprises an Fc-specific polymer-conjugated antibody, as described herein, covalently linked to a signal-generating moiety through a heterobifunctional polyalkyleneglycol linker having the general structure shown below:

A^(CH₂)_X-O-| E y wherein A and B include different reactive groups, x is an integer from 2 to 10 (such as 2, 3 or 4), and y is an integer from 1 to 50, for example, from 2 to 30 such as from 3 to 20 or from 4 to 12. One or more hydrogen atoms can be substituted for additional functional groups such as hydroxyl groups, alkoxy groups (such as methoxy and ethoxy), halogen atoms (F, Cl, Br, I), sulfato groups and amino groups (including mono- and di-substituted amino groups such as dialkyl amino groups).

A and B of the linker can independently include a carbonyl- reactive group, an amine-reactive group, a thiol-reactive group or a photo- reactive group, but are not the same. Examples of carbonyl-reactive groups include aldehyde- and ketone-reactive groups like hydrazine derivatives and amines. Examples of amine-reactive groups include active esters such as NHS or sulfo-NHS, isothiocyanates, isocyanates, acyl azides, sulfonyl chlorides, aldehydes, glyoxals, epoxides, oxiranes, carbonates, aryl halides, imidoesters, anhydrides and the like. Examples of thiol-reactive groups include non- polymerizable Michael acceptors, haloacetyl groups (such as iodoacetyl), alkyl halides, maleimides, aziridines, acryloyl groups, vinyl sulfones, benzoquinones, aromatic groups that can undergo nucleophilic substitution such as fluorobenzene groups (such as tetra and pentafluorobenzene groups), and disulfide groups such as pyridyl disulfide groups and thiols activated with Ellman's reagent. Examples of photo-reactive groups include aryi azide and halogenated aryl azides. Additional examples of each of these types of groups will be apparent to those skilled in the art. Further examples and information regarding reaction conditions and methods for exchanging one type of reactive group for another are provided in Hermanson, "Bioconjugate Techniques," Academic Press, San Diego, 1996, which is incorporated by reference herein. In a particular embodiment, a thiol-reactive group is other than vinyl sulfone. In some embodiments, a thiol-reactive group of the heterobifunctional linker is covalently linked to the antibody and an amine- reactive group of the heterobifunctional linker is covalently linked to the signal- generating moiety, or vice versa. For example, a thiol-reactive group of the heterobifunctional linker can be covalently linked to a cysteine residue (such as formed by reduction of a cystine bridge) of the antibody or a thiol-reactive group of the heterobifunctional linker can be covalently linked to a thiol group that is introduced to the antibody, and the amine-reactive group is covalently linked to the signal-generating moiety.

Alternatively, an aldehyde-reactive group of the heterobifunctional linker can be covalently linked to the antibody and an amine-reactive group of the heterobifunctional linker can be covalently linked to the signal-generating moiety, or vice versa. In a particular embodiment, an aldehyde-reactive group of the heterobifunctional linker can be covalently linked to an aldehyde formed on a glycosylated portion of an antibody, and the amine-reactive group is covalently linked to the signal-generating moiety.

In yet other embodiments, an aldehyde-reactive group of the heterobifunctional linker is covalently linked to the antibody and a thiol-reactive group of the heterobifunctional linker is covalently linked to the signal- generating moiety, or vice versa. In particular embodiments, a method of preparing an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate comprises generating a thiol reactive signal-generating moiety by methods well known to those having ordinary skill in the art. As used herein, the term "thiol reactive group(s)" refers to an atom or atoms that can react with and form a covalent bond with a thiol group. A thiol reactive group can be an intrinsic part of a molecule or can be introduced to the molecule through reaction with one or more other molecules. Illustrative examples of thiol-reactive groups include non-polymerizable Michael acceptors, haloacetyl groups (such as bromoacetyl and iodoacetyl groups), alkyl halides, maleimides, aziridines, acryloyl groups, vinyl sulfones, benzoquinones, aromatic groups that can undergo nucleophilic substitution such as fluorobenzene groups (such as tetra and pentafluorobenzene groups), and disulfide groups such as pyridyl disulfide groups and thiols activated with Ellman's reagent. Further examples and information regarding reaction conditions and methods for exchanging one type of reactive group for another to add a thiol-reactive group are provided in Hermanson, "Bioconjugate Techniques," Academic Press, San Diego, 1996, ISBN 0-12-342336-8, which is incorporated by reference herein.

For example, in one embodiment, thiol-reactive maleimide ester is reacted with a signal generating moiety such as alkaline phosphatase to generate a thiol-reactive signal-generating moiety. In particular embodiments, a heterobifunctional polyalkylene glycol linker, links an amine-reactive group (active ester) and a thiol-reactive group (maleimide).

An exemplary, non-limiting example, for the preparation of a thiol reactive signal-generating moiety comprises passing alkaline phosphatase (AP) (Biozyme, San Diego, CA), in a reactive buffer containing Tris, over a PD-10 column in order to exchange the AP into a non-reactive buffer (0.1 M sodium phosphate, 0.1 M sodium chloride, 1 mM magnesium chloride, 0.1 mM zinc chloride, pH = 7.5). Then, to a solution of alkaline phosphatase (0.8 ml, 17.5 mg/ml) a 100-fold excess of a thiol-reactive maleimide ester such as NHS- dPEG_m ^™-MAL (NHS (N-hydroxy-succinimide); dPEG (discrete PEG); MAL(maleimide); Quanta Biodesign, Powell, OH) is added and the reaction is rotated for a period of about 1 h. The resultant thiol-reactive signal-generating moiety is denoted as AP-PEG_m-MAL

In particular embodiments, the subscript m indicates the number of PEG monomer units in a discrete PEG. In certain embodiments, m= 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12 or more PEG monomer units. In particular illustrative embodiments, m= 4, 8, or 12 PEG monomer units. In certain illustrative embodiments, m = 12 PEG monomer units.

Size exclusion chromatography (Superdex 200; 0.1 M Tris, 1 mM MgCI₂, 0.1 mM ZnCI₂, pH = 7.5) yields the purified maleimido-alkaline phosphatase. The number of maleimides may be quantitated using a modified Ellman's assay (see, for example, Hermanson, "Bioconjugate Techniques," Academic Press, San Diego, 1996, ISBN 0-12-342336-8, which is incorporated by reference herein), and on average 17-25 maleimide groups may be introduced to each alkaline phosphatase enzyme. In a particular embodiment, the final conjugation step in forming an Fc-specific PEGylated antibody signal-generating moiety conjugate comprises reacting a thiolated Fc-specific PEGylated antibody with the thiol reactive signal-generating moiety (e.g., AP-PEG_m-MAL) at a pH above 7, which in this instance allows for fast formation of a conjugate by reaction of the thiol on the Fc-specific PEGylated antibody (present to a greater extent in the conjugate base thiolate form at higher pHs) and the thiol-reactive maleimide group introduced to alkaline phosphatase.

Illustratively, the purified maleimido-alkaline phosphatase may be combined with the purified thiolated antibody in about a 1 :1 molar ratio and rotated for a period of about 18 h. Size exclusion chromatography (Superdex 200; 0.1 M Tris, 1 mM MgCI₂, 0.1 mM ZnCI₂, pH = 7.5) yields a purified conjugate which may be suitably diluted (e.g., in Stabilzyme™ AP enzyme- stabilizing diluent (SurModics, Eden Prairie, MN)).

In another illustrative embodiment, HRP (Horseradish Peroxidase, Pierce, Rockford, IL) may be reconstituted from a lyophilized powder to a final concentration of about 25 mg/mL solution (0.1 M sodium phosphate, 0.15M sodium chloride, pH = 7.5). In particular embodiments, a heterobifunctional polyalkylene glycol linker links an amine-reactive group (active ester) and a thiol-reactive group (maleimide). For example, 100 fold molar excess of NHS dPEGm™ MAL ester (Quanta Biodesign, Powell, OH) may be added to the HRP solution, the vial rotated in the dark at ambient temperature (23 - 25⁰C), and the amide bond forming reaction may be allowed to proceed for 1 hour. The resultant thiol-reactive signal-generating moiety is denoted as HRP-PEG_m-MAL.

Size exclusion chromatography (Superdex 200; 0.1 M Tris, 1 mM MgCI₂, 0.1 mM ZnCb, pH = 7.5) can be used to yield a purified maleimido- horseradish peroxidase. The number of maleimides may be quantitated using a modified Ellman's assay (see, for example, Hermanson, "Bioconjugate Techniques," Academic Press, San Diego, 1996, ISBN 0-12-342336-8, which is incorporated by reference herein), and on average 5-7 maleimide groups may be introduced to each horseradish peroxidase enzyme. In a particular embodiment, the final conjugation step in forming an Fc-specific PEGylated antibody signal-generating moiety conjugate comprises reacting a thiolated Fc-specific PEGylated antibody with the thiol reactive signal-generating moiety (e.g., HRP-PEG_m-MAL) at a pH above 7, which in this instance allows for fast formation of a conjugate by reaction of the thiol on the Fc-specific PEGylated antibody (present to a greater extent in the conjugate base thiolate form at higher pHs) and the thiol-reactive maleimide group introduced to horseradish peroxidase.

Illustratively, the purified horseradish peroxidase PEG maleimide (i.e., HRP-PEG_m-MAL) may be combined with the purified thiolated antibody in about a 3:1 molar ratio and rotated for a period of about 16 h. Size exclusion chromatography (Superdex 200; 0.1 M Tris, 1 mM MgCi₂, 0.1 mM ZnCI₂, pH = 7.5) can be used to yield the purified conjugate.

Accordingly, in certain specific embodiments, the present invention provides a method for preparing an Fc-specific PEGylated antibody signal generating conjugate that comprises: i) reacting an antibody with an oxidant to form reactive aldehyde groups in the Fc-portion of the antibody; ii) reacting the aldehyde-bearing antibody with a nucleophilic PEG derivative to form an antibody-PEG intermediate; iii) stabilizing the antibody-PEG intermediate to form an Fc-specific PEGylated antibody; iv) generating a thiolated Fc-specific PEGylated antibody; v) synthesizing a thiol reactive signal- generating moiety; and vi) reacting the thiolated Fc-specific PEGylated antibody of step iv) with the thiol reactive signal-generating moiety of step v), thereby forming an Fc-specific PEGylated antibody signal-generating moiety conjugate. Furthermore, an Fc-specific polymer-conjugated antibody signal- generating moiety conjugate of the present invention can comprise a single signal-generating moiety or multiple signal-generating moieties. Furthermore, multiple Fc-specific polymer-conjugated antibodies can be conjugated to a single signal-generating moiety or any number of signal-generating moieties to a single Fc-specific polymer-conjugated antibody.

III. Antibodies

The Fc-specific polymer-conjugated antibodies of the invention may be of essentially any type and of any origin provided they possess binding specificity for a target molecule of interest and retain an Fc region for polymer- conjugation as described herein. For example, the antibodies may be monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies) formed from at least two intact antibodies, antibody fragments, and the like, so long as they exhibit the desired biological specificity.

In particular embodiments, an Fc-specific polymer-conjugated antibody of the invention comprises a monoclonal antibody. In related embodiments, an Fc-specific polymer-conjugated antibody comprises a primary antibody.

In other particular embodiments, an Fc-specific polymer- conjugated antibody of the invention comprises a polyclonal antibody. In related embodiments, the Fc-specific polymer-conjugated antibody comprises a secondary antibody.

In certain embodiments, an Fc-specific polymer-conjugated antibody of the present invention specifically recognizes or binds to any particular biological molecule, including, but not limited to proteins, nucleic acid sequences, carbohydrates, lipids, and haptens or any particular group of highly similar molecules.

In certain particular embodiments, an Fc-specific polymer- conjugated antibody comprises an anti-hapten antibody (which can, for example, be used to detect a hapten-labeled probe sequence directed to a nucleic acid sequence of interest). Illustrative examples of haptens include, but are not limited to fluorescein, dinitrophenol (DNP), digoxigenin (DIG) and biotin.

In other particular embodiments, an Fc-specific polymer- conjugated antibody comprises an anti-antibody antibody that can be used as a secondary antibody in a diagnostic assay, e.g., an immunoassay. For example, an Fc-specific polymer-conjugated antibody can comprise an anti-lgG antibody such as an anti-mouse IgG antibody, an anti-rabbit IgG antibody or an anti-goat IgG antibody.

An "isolated" antibody is one which has been identified and separated and/or recovered from a component of its natural environment. Contaminant components of its natural environment are materials which would interfere with research, diagnostic or therapeutic uses for the antibody, and may include enzymes, hormones, and other proteinaceous or nonproteinaceous solutes. In some embodiments, an antibody is purified (1) to greater than 95% by weight of antibody as determined by, for example, the Lowry method, and in some embodiments, to greater than 99% by weight; (2) to a degree sufficient to obtain at least 15 residues of N-terminal or internal amino acid sequence by use of, for example, a spinning cup sequenator, or (3) to homogeneity by SDS- PAGE under reducing or nonreducing conditions using, for example, Coomassie blue or silver stain. Isolated antibody includes the antibody in situ within recombinant cells since at least one component of the antibody's natural environment will not be present. Ordinarily, however, isolated antibody will be prepared by at least one purification step.

"Native antibodies" are usually heterotetrameric glycoproteins of about 150,000 daltons, composed of two identical light (L) chains and two identical heavy (H) chains. Each light chain is linked to a heavy chain by one covalent disulfide bond, while the number of disulfide linkages varies among the heavy chains of different immunoglobulin isotypes. Each heavy and light chain also has regularly spaced intrachain disulfide bridges. Each heavy chain has at one end a variable domain (VH) followed by a number of constant domains. Each light chain has a variable domain at one end (VL) and a constant domain at its other end; the constant domain of the light chain is aligned with the first constant domain of the heavy chain, and the light chain variable domain is aligned with the variable domain of the heavy chain. Particular amino acid residues are believed to form an interface between the light chain and heavy chain variable domains. The "variable region" or "variable domain" of an antibody refers to the amino-terminal domains of the heavy or light chain of the antibody. The variable domain of the heavy chain may be referred to as "VH." The variable domain of the light chain may be referred to as "VL." These domains are generally the most variable parts of an antibody and contain the antigen-binding sites.

The term "variable" refers to the fact that certain portions of the variable domains differ extensively in sequence among antibodies and are used in the binding and specificity of each particular antibody for its particular antigen. However, the variability is not evenly distributed throughout the variable domains of antibodies. It is concentrated in three segments called hypervariable regions (HVRs) both in the light-chain and the heavy-chain variable domains. The more highly conserved portions of variable domains are called the framework regions (FR). The variable domains of native heavy and light chains each comprise four FR regions, largely adopting a beta-sheet configuration, connected by three HVRs, which form loops connecting, and in some cases forming part of, the beta-sheet structure. The HVRs in each chain are held together in close proximity by the FR regions and, with the HVRs from the other chain, contribute to the formation of the antigen-binding site of antibodies (see Kabat et ai, Sequences of Proteins of Immunological Interest, Fifth Edition, National Institute of Health, Bethesda, Md. (1991)). The constant domains are not involved directly in the binding of an antibody to an antigen, but exhibit various effector functions, such as participation of the antibody in antibody-dependent cellular toxicity.

The "light chains" of antibodies (immunoglobulins) from any vertebrate species can be assigned to one of two clearly distinct types, called kappa (K) and lambda (λ), based on the amino acid sequences of their constant domains.

Depending on the amino acid sequences of the constant domains of their heavy chains, antibodies (immunoglobulins) can be assigned to different classes. There are five major classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM, and several of these may be further divided into subclasses

(isotypes), e.g., IgGI , lgG2, lgG3, lgG4, IgAI , and lgA2. The heavy chain constant domains that correspond to the different classes of immunoglobulins are called α, δ, ε, y, and μ, respectively. The subunit structures and three- dimensional configurations of different classes of immunoglobulins are well known and described generally in, for example, Abbas et al. Cellular and MoI. Immunology, 4th ed. (W.B. Saunders, Co., 2000). An antibody may be part of a larger fusion molecule, formed by covalent or non-covalent association of the antibody with one or more other proteins or peptides.

The terms "full length antibody," "intact antibody" and "whole antibody" are used herein interchangeably to refer to an antibody in its substantially intact form, not antibody fragments as defined below. The terms particularly refer to an antibody with heavy chains that contain an Fc region. "Antibody fragments" comprise a portion of an intact antibody, preferably comprising the antigen binding region thereof. Examples of antibody fragments include Fab, Fab', F(ab')2, and Fv fragments; diabodies; linear antibodies; single-chain antibody molecules; and multispecific antibodies formed from antibody fragments.

The term "monoclonal antibody" as used herein refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible mutations, e.g., naturally occurring mutations, that may be present in minor amounts. Thus, the modifier "monoclonal" indicates the character of the antibody as not being a mixture of discrete antibodies. In certain embodiments, such a monoclonal antibody typically includes an antibody comprising a polypeptide sequence that binds a target, wherein the target-binding polypeptide sequence was obtained by a process that includes the selection of a single target binding polypeptide sequence from a plurality of polypeptide sequences. For example, the selection process can be the selection of a unique clone from a plurality of clones, such as a pool of hybridoma clones, phage clones, or recombinant DNA clones. It should be understood that a selected target binding sequence can be further altered, for example, to improve affinity for the target, to humanize the target binding sequence, to improve its production in cell culture, to reduce its immunogenicity in vivo, to create a multispecific antibody, etc., and that an antibody comprising the altered target binding sequence is also a monoclonal antibody of this invention. In contrast to polyclonal antibody preparations, which typically include different antibodies directed against different determinants (epitopes), each monoclonal antibody of a monoclonal antibody preparation is directed against a single determinant on an antigen. In addition to their specificity, monoclonal antibody preparations are advantageous in that they are typically uncontaminated by other immunoglobulins. The monoclonal antibodies herein specifically include "chimeric" antibodies in which a portion of the heavy and/or light chain is identical with or homologous to corresponding sequences in antibodies derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical with or homologous to corresponding sequences in antibodies derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit the desired biological activity (U.S. Pat. No. 4,816,567; and Morrison et al., PNAS USA 81 :6851-6855 (1984)). Polyclonal antibodies can be raised in a mammalian host (e.g., mouse, goat, rabbit, and the like), for example, by one or more injections of an immunogen and, if desired, an adjuvant. Typically, the immunogen and/or adjuvant are injected in the mammal by multiple subcutaneous or intraperitoneal injections. Examples of adjuvants include Freund's complete and monophosphoryl Lipid A synthetic-trehalose dicorynomycolate (MPL-TDM). To improve the immune response, an immunogen may be conjugated to a protein that is immunogenic in the host, such as keyhole limpet hemocyanin (KLH), serum albumin, bovine thyroglobulin, and soybean trypsin inhibitor. Protocols for antibody production are described by (Ausubel et al., 1987; Harlow and Lane, 1988). Alternatively, polyclonal antibodies may be made in chickens, producing IgY molecules (Schade et al., 1996).

The term "diabodies" refers to antibody fragments with two antigen-binding sites, which fragments comprise a heavy-chain variable domain (VH) connected to a light-chain variable domain (VL) in the same polypeptide chain (VH-VL). By using a linker that is too short to allow pairing between the two domains on the same chain, the domains are forced to pair with the complementary domains of another chain and create two antigen-binding sites. Diabodies may be bivalent or bispecific. Diabodies are described more fully in, for example, EP 404,097; WO 1993/01161 ; Hudson et al., Nat. Med. 9:129-134 (2003); and Hollinger et al., PNAS USA 90: 6444-6448 (1993). Triabodies and tetrabodies are also described in Hudson et al., Nat. Med. 9:129-134 (2003). An "antigen" is a predetermined moiety to which an antibody can selectively bind. The target antigen may be polypeptide, carbohydrate, nucleic acid, lipid, hapten or other naturally occurring or synthetic compound. In various embodiments of the invention, the target antigen is a polypeptide. "Binding affinity" generally refers to the strength of the sum total of noncovalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen). Unless indicated otherwise, as used herein, "binding affinity" refers to intrinsic binding affinity which reflects a 1 :1 interaction between members of a binding pair (e.g., antibody and antigen). The affinity of a molecule X for its partner Y can generally be represented by the dissociation constant (KDa). Affinity can be measured by common methods known in the art, including those described herein. Low- affinity antibodies generally bind antigen slowly and tend to dissociate readily, whereas high-affinity antibodies generally bind antigen faster and tend to remain bound longer. A variety of methods of measuring binding affinity are known in the art, any of which can be used for purposes of the present invention. Specific illustrative embodiments are described in the following.

In some embodiments, amino acid sequence modification(s) of the antibodies described herein are contemplated. For example, it may be desirable to improve the binding affinity and/or other biological properties of the antibody. Amino acid sequence variants of the antibody may be prepared by introducing appropriate changes into the nucleotide sequence encoding the antibody, or by peptide synthesis. Such modifications include, for example, deletions from, and/or insertions into and/or substitutions of, residues within the amino acid sequences of the antibody. Any combination of deletion, insertion, and substitution can be made to arrive at the final construct, provided that the final construct possesses the desired characteristics. The amino acid alterations may be introduced in the subject antibody amino acid sequence, for example, at the time that sequence is made. In certain embodiments, an antibody of the invention may be altered to increase or decrease the extent to which the antibody is glycosylated. Glycosylation of polypeptides is typically either N-linked or O-linked. N-linked refers to the attachment of a carbohydrate moiety to the side chain of an asparagine residue. The tripeptide sequences asparagine-X-serine and asparagine-X-threonine, where X is any amino acid except proline, are the recognition sequences for enzymatic attachment of the carbohydrate moiety to the asparagine side chain. Thus, the presence of either of these tripeptide sequences in a polypeptide creates a potential glycosylation site. O-linked glycosylation refers to the attachment of one of the sugars N- aceylgalactosamine, galactose, or xylose to a hydroxyamino acid, most commonly serine or threonine, although 5-hydroxyproline or 5-hydroxylysine may also be used.

Addition or deletion of glycosylation sites to the antibody is conveniently accomplished by altering the amino acid sequence such that one or more of the above-described tripeptide sequences (for N-linked glycosylation sites) is created or removed. The alteration may also be made by the addition, deletion, or substitution of one or more serine or threonine residues to the sequence of the original antibody (for O-linked glycosylation sites).

In other embodiments, the carbohydrates attached to the Fc region of an antibody may be altered in order to improve properties and/or alter polymer conjugation (e.g., PEGylation) chemistries used according to the invention. Native antibodies produced by mammalian cells typically comprise a branched, biantennary oligosaccharide that is generally attached by an N- linkage to Asn297 of the CH2 domain of the Fc region. See, e.g. , Wright et al. (1997) TIBTECH 15:26-32. The oligosaccharide may include various carbohydrates, e.g., mannose, N-acetyl glucosamine (GIcNAc), galactose, and sialic acid, as well as a fucose attached to a GIcNAc in the "stem" of the biantennary oligosaccharide structure.

It may also be desirable, in certain embodiments, to introduce one or more amino acid modifications or other alterations in an Fc region of antibodies of the invention, thereby generating an Fc region variant. The Fc region variant may comprise a Fc region sequence comprising an amino acid modification (e.g., a substitution) at one or more amino acid positions.

In yet another embodiment, it may be desirable to create cysteine engineered antibodies, e.g., "thioMAbs," and "thioFabs" in which one or more residues of an antibody are substituted with cysteine residues. In particular embodiments, the substituted residues occur at accessible sites of the antibody. By substituting those residues with cysteine, reactive thiol groups are thereby positioned at accessible sites of the antibody and may be used to conjugate the antibody to other moieties, such as signal-generating moieties. The antibodies of the present invention can also be modified with polymers related to PEG, copolymers containing PEG, and the like. Such may be used in place of, or in addition to, the PEG molecules or derivatives described herein. For example, various water soluble polymers can be used for derivatizing antibodies. Non-limiting examples of water soluble polymers include, but are not limited to, copolymers of ethylene glycol/propylene glycol, carboxymethylcellulose, dextran, polyvinyl alcohol, polyvinyl pyrrolidone, poly- 1 ,3-dioxolane, poly-1 ,3,6-trioxane, ethylene/maleic anhydride copolymer, polyaminoacids (either homopolymers or random copolymers), and dextran or poly(n-vinyl pyrrolidone)polyethylene glycol, propropylene glycol homopolymers, polypropylene oxide/ethylene oxide co-polymers, polyoxyethylated polyols (e.g., glycerol), polyvinyl alcohol, and mixtures thereof.

In particular embodiments, polymers used for derivatizing an antibody of the invention comprise about 1 to 50, 2 to 30, 3 to 20, or 4 to 12 monomeric units. In certain embodiments, polymers comprise at least about 1 , 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 monomer units. In certain particular embodiments, the polymers are of varied lengths in the range of about 1 to 50, 10 to 40, or 20 to 30 monomer units. In other embodiments, the number of monomer units in a polymer is such that the molecular weight of the polymer itself is less than 2 kDa, less than 1.5 kDa, less than 1 kDa, or less than 500 D. In more particular embodiments, the molecular weight of the polymer is about 2 kDa, about 1.8 kDa, about 1.8 kDa, about 1.5 kDa, about 1.2 kDa, about 1.0 kDa, about 0.8 kDa, about 0.7 kDa, about 0.6 kDa, about 0.5 kDa, or about 0.2 kDa. In certain embodiments, the polymers are of varied molecular weights in the range of about 2 kDa to 0.5 kDa, about 1.5 kDa, to 0.5 kDa, about 1.0 kDa to 0.5 kDa, or about 0.5 kDa to 0.1 kDa. Antibodies may be prepared by any of a variety of techniques known to those of ordinary skill in the art. See, e.g., Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, 1988. In general, antibodies can be produced by cell culture techniques, including the generation of monoclonal antibodies as described herein, or via transfection of antibody genes into suitable bacterial or mammalian cell hosts, in order to allow for the production of recombinant antibodies.

Suitable host cells for cloning or expressing the DNA in the vectors herein are the prokaryote, yeast, or higher eukaryote cells described above. Suitable prokaryotes for this purpose include eubacteria, such as Gram-negative or Gram-positive organisms, for example, Enterobacteriaceae such as Escherichia, e.g., E. coli, Enterobacter, Erwinia, Klebsiella, Proteus, Salmonella, e.g., Salmonella typhimurium, Serratia, e.g., Serratia marcescans, and Shigella, as well as Bacilli such as B. subtilis and B. licheniformis (e.g., B. licheniformis 41 P disclosed in DD 266,710 published 12 Apr. 1989), Pseudomonas such as P. aeruginosa, and Streptomyces. One preferred E. coli cloning host is E. coli 294 (ATCC 31 ,446), although other strains such as E. coli B, E. coli X1776 (ATCC 31 ,537), and E. coli W3110 (ATCC 27,325) are suitable. These examples are illustrative rather than limiting.

Full length antibody, antibody fusion proteins, and antibody fragments can be produced in bacteria. Full length antibodies have greater half life in circulation. Production in E. coli is faster and more cost efficient. For expression of antibody fragments and polypeptides in bacteria, see, e.g., U.S. Pat. No. 5,648,237 (Carter et. al.), U.S. Pat. No. 5,789,199 (JoIy et a/.), U.S. Pat. No. 5,840,523 (Simmons et al.), which describes translation initiation region (TIR) and signal sequences for optimizing expression and secretion. See also Charlton, Methods in Molecular Biology, Vol. 248 (B.K.C. Lo, ed., Humana Press, Totowa, N. J., 2003), pp. 245-254, describing expression of antibody fragments in E. coli. After expression, the antibody may be isolated from the E. coli cell paste in a soluble fraction and can be purified through, e.g., a protein A or G column depending on the isotype. Final purification can be carried out similar to the process for purifying antibody expressed e.g, in CHO cells.

In addition to prokaryotes, eukaryotic microbes such as filamentous fungi or yeast are suitable cloning or expression hosts for antibody- encoding vectors. Saccharomyces cerevisiae, or common baker's yeast, is the most commonly used among lower eukaryotic host microorganisms. However, a number of other genera, species, and strains are commonly available and useful herein, such as Schizosaccharomyces pombe; Kluyveromyces hosts such as, e.g., K. lactis, K. fragilis (ATCC 12,424), K. bulgaricus (ATCC 16,045), K wickeramii (ATCC 24,178), K. waltii (ATCC 56,500), K. drosophilarum (ATCC 36,906), K. thermotolerans, and K. marxianus; yarrowia (EP 402,226); Pichia pastoris (EP 183,070); Candida; Trichoderma reesia (EP 244,234); Neurospora crassa; Schwanniomyces such as Schwanniomyces occidentalis; and filamentous fungi such as, e.g., Neurospora, Penicillium, Tolypocladium, and Aspergillus hosts such as A. nidulans and A. niger. For a review discussing the use of yeasts and filamentous fungi for the production of therapeutic proteins, see, e.g., Gerngross, Nat. Biotech. 22:1409-1414 (2004).

Certain fungi and yeast strains may be selected in which glycosylation pathways have been "humanized," resulting in the production of an antibody with a partially or fully human glycosylation pattern. See, e.g., Li et a/., Nat. Biotech. 24:210-215 (2006) (describing humanization of the glycosylation pathway in Pichia pastoris); and Gerngross et al., supra.

Suitable host cells for the expression of glycosylated antibody are also derived from multicellular organisms (invertebrates and vertebrates). Examples of invertebrate cells include plant and insect cells. Numerous baculoviral strains and variants and corresponding permissive insect host cells from hosts such as Spodoptera frugiperda (caterpillar), Aedes aegypti (mosquito), Aedes albopictus (mosquito), Drosophila melanogaster (fruitfly), and Bombyx mori have been identified. A variety of viral strains for transfection are publicly available, e.g., the L-1 variant of Autographa californica NPV and the Bm-5 strain of Bombyx mori NPV, and such viruses may be used as the virus herein according to the present invention, particularly for transfection of Spodoptera frugiperda cells.

Plant cell cultures of cotton, corn, potato, soybean, petunia, tomato, duckweed (Lemnaceae), alfalfa (M. truncatula), and tobacco can also be utilized as hosts. See, e.g., U.S. Pat. Nos. 5,959,177, 6,040,498, 6,420,548, 7,125,978, and 6,417,429 (describing PLANTIBODIES™ technology for producing antibodies in transgenic plants).

Vertebrate cells may be used as hosts, and propagation of vertebrate cells in culture (tissue culture) has become a routine procedure. Examples of useful mammalian host cell lines are monkey kidney CV1 line transformed by SV40 (COS-7, ATCC CRL 1651); human embryonic kidney line (293 or 293 cells subcloned for growth in suspension culture, Graham et al., J. Gen Virol. 36:59 (1977)); baby hamster kidney cells (BHK, ATCC CCL 10); mouse Sertoli cells (TM4, Mather, Biol. Reprod. 23:243-251 (1980)); monkey kidney cells (CV1 ATCC CCL 70); African green monkey kidney cells (VERO- 76, ATCC CRL-1587); human cervical carcinoma cells (HELA, ATCC CCL 2); canine kidney cells (MDCK, ATCC CCL 34); buffalo rat liver cells (BRL 3A, ATCC CRL 1442); human lung cells (W138, ATCC CCL 75); human liver cells (Hep G2, HB 8065); mouse mammary tumor (MMT 060562, ATCC CCL51 ); TR1 cells (Mather et al., Annals N.Y. Acad. Sci. 383:44-68 (1982)); MRC 5 cells; FS4 cells; and a human hepatoma line (Hep G2). Other useful mammalian host cell lines include Chinese hamster ovary (CHO) cells, including DHFR-CHO cells (Urlaub et al., PNAS USA 77:4216 (1980)); and myeloma cell lines such as NSO and Sp2/0. For a review of certain mammalian host cell lines suitable for antibody production, see, e.g., Yazaki and Wu, Methods in Molecular Biology, Vol. 248 (B. K.C Lo, ed., Humana Press, Totowa, NJ. , 2003), pp. 255-268. Host cells are transformed with the above-described expression or cloning vectors for antibody production and cultured in conventional nutrient media modified as appropriate for inducing promoters, selecting transformants, or amplifying the genes encoding the desired sequences. In one technique, an immunogen comprising the polypeptide is initially injected into any of a wide variety of mammals (e.g., mice, rats, rabbits, sheep or goats). In this step, the polypeptides of this invention may serve as the immunogen without modification. Alternatively, particularly for relatively short polypeptides, a superior immune response may be elicited if the polypeptide is joined to a carrier protein, such as bovine serum albumin or keyhole limpet hemocyanin. The immunogen is injected into the animal host, preferably according to a predetermined schedule incorporating one or more booster immunizations, and the animals are bled periodically. Polyclonal antibodies specific for the polypeptide may then be purified from such antisera by, for example, affinity chromatography using the polypeptide coupled to a suitable solid support.

Monoclonal antibodies specific for an antigenic polypeptide of interest may be prepared, for example, using the technique of Kohler and Milstein, Eur. J. Immunol. 6:511-519, 1976, and improvements thereto. Briefly, these methods involve the preparation of immortal cell lines capable of producing antibodies having the desired specificity (Ae., reactivity with the polypeptide of interest). Such cell lines may be produced, for example, from spleen cells obtained from an animal immunized as described above. The spleen cells are then immortalized by, for example, fusion with a myeloma cell fusion partner, preferably one that is syngeneic with the immunized animal. A variety of fusion techniques may be employed. For example, the spleen cells and myeloma cells may be combined with a nonionic detergent for a few minutes and then plated at low density on a selective medium that supports the growth of hybrid cells, but not myeloma cells. A preferred selection technique uses HAT (hypoxanthine, aminopterin, thymidine) selection. After a sufficient time, usually about 1 to 2 weeks, colonies of hybrids are observed. Single colonies are selected and their culture supernatants tested for binding activity against the polypeptide. Hybridomas having high reactivity and specificity are preferred.

Monoclonal antibodies may be isolated from the supernatants of growing hybridoma colonies. In addition, various techniques may be employed to enhance the yield, such as injection of the hybridoma cell line into the peritoneal cavity of a suitable vertebrate host, such as a mouse. Monoclonal antibodies may then be harvested from the ascites fluid or the blood. Contaminants may be removed from the antibodies by conventional techniques, such as chromatography, gel filtration, precipitation, and extraction. The polypeptides of this invention may be used in the purification process in, for example, an affinity chromatography step.

It will be evident to those skilled in the art that a variety of bifunctional or polyfunctional reagents, both homo- and hetero-functional (such as those described in the catalog of the Pierce Chemical Co., Rockford, IL), may be employed as the linker group. Coupling may be effected, for example, through amino groups, carboxyl groups, sulfhydryl groups or oxidized carbohydrate residues. There are numerous references describing such methodology, e.g., U.S. Patent No. 4,671 ,958, to Rodwell et al. It may be desirable to couple more than one agent to an antibody.

In one embodiment, multiple molecules of an agent are coupled to one antibody molecule. In another embodiment, more than one type of agent may be coupled to one antibody. Regardless of the particular embodiment, immunoconjugates with more than one agent may be prepared in a variety of ways. For example, more than one agent may be coupled directly to an antibody molecule, or linkers which provide multiple sites for attachment can be used. Alternatively, a carrier can be used.

Also provided herein are anti-idiotypic antibodies that mimic an immunogenic portion of a polypeptide of the present invention. Such antibodies may be raised against an antibody, or antigen-binding fragment thereof, that specifically binds to an immunogenic portion of a polypeptide of the present invention, using well known techniques. Anti-id iotypic antibodies that mimic an immunogenic portion of a polypeptide of the present invention are those antibodies that bind to an antibody, or antigen-binding fragment thereof, that specifically binds to an immunogenic portion of a polypeptide of the present invention, as described herein.

IV. Diagnostic Methods

The disclosed Fc-specific antibodies (e.g., Fc-specific PEGylated antibodies) and conjugates of the invention are particularly advantageous in diagnostic assays for detecting molecules of interest in essentially any type of binding immunoassay, including immunohistochemical binding assays. In certain preferred embodiments, the polymer-conjugated antibody further comprises a signal-generating moiety (e.g., the antibody is an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate).

In one embodiment, the disclosed antibodies are used as a labeled primary antibody in an immunoassay, for example, a primary antibody directed to a particular molecule or a hapten-labeled molecule. In particular embodiments, wherein the molecule of interest (e.g., antigen) is multi-epitopic, a mixture of conjugates directed to the multiple epitopes can be used. For example, a mixture can comprise a combination of 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more Fc-specific PEGylated antibodies.

In another embodiment, the disclosed antibodies and conjugates are used as secondary antibodies in an immunoassay (for example, directed to a primary antibody that binds the target molecule (e.g., molecule of interest); the target molecule can be bound by two primary antibodies in a sandwich-type assay when multi-epitopic).

In yet another embodiment, mixtures of disclosed conjugates are used to provide further amplification of a signal due to a molecule of interest bound by a primary antibody (the molecule of interest (e.g., target molecule) can be bound by two primary antibodies in a sandwich-type assay). For example, a first Fc-specific polymer-conjugated antibody signal-generating moiety conjugate in a mixture is directed to a primary antibody that binds a molecule of interest and a second Fc-specific polymer- conjugated antibody signal-generating moiety conjugate is directed to the antibody portion of the first conjugate, thereby localizing more signal-generating moieties at the site of the molecule of interest. Other types of assays in which the disclosed conjugates can be used will be readily apparent to those skilled in the art.

The disclosed Fc-specific polymer-conjugated antibody signal- generating moiety conjugates (e.g., Fc-specific PEGylated antibody signal- generating moiety conjugates) of the present invention are useful in the context of essentially any biological or other assays or analysis wherein determining the quantity and/or localization of a target molecule (e.g., molecule of interest) in a biological sample is desired. Illustrative examples of a biological sample, include, but are not limited to urine, blood, sera, sputum, tissue, and cellular samples. Tissues samples may be derived from any tissue by using methods well known in the art.

For example, the compositions of the invention are useful in any of a number of assays involving the detection, monitoring, and/or diagnosis of various diseases, disorders, and conditions that may be manifested by abnormal gene expression, protein expression and/or genetic rearrangements.

Various embodiments of the present invention relate, in part, to methods of detecting molecules of interest (e.g., a biological molecule) in a sample, such as a cell or tissue. Such methods can be applied in a variety of known detection formats, including, but not limited to immunohistochemistry (IHC), immunocytochemistry (ICC), flow cytometry, enzyme immuno-assay (EIA), and enzyme linked immuno-assay (ELISA).

Signal-generating moieties may be linked to any Fc-specific polymer conjugated antibody (e.g., Fc-specific PEGylated antibody) that specifically binds to a molecule of interest or target molecule, e.g., an antibody, a protein, a carbohydrate, a lipid, a nucleic acid, a hapten or a polymer. In a particular embodiment, the molecule of interest is a biological molecule selected from the group consisting of: an antibody, a protein, a carbohydrate, a lipid, and a nucleic acid.

Multiple signal-generating moieties can also be conjugated to an Fc-specific polymer-conjugated antibody (e.g., Fc-specific PEGylated antibody) or multiple Fc-specific polymer conjugated antibodies. Moreover, each additional Fc-specific polymer-conjugated antibody signal generating conjugate (e.g., Fc-specific PEGylated antibody signal-generating moiety conjugate) used to characterize a molecule of interest (e.g., a biological molecule) may serve as a signal amplification step. The molecule of interest may be detected visually using, e.g., light microscopy, fluorescent microscopy, electron microscopy where the signal generating moiety is for example a dye, a colloidal gold particle, a luminescent reagent. Visually detection of Fc-specific PEGylated antibody enzymatically labeled conjugates bound to a molecule of interest (e.g., a biological molecule) may also be detected using a spectrophotometer. Where the signal-generating moiety is a radioactive isotope, visual detection via autoradiography or non-visual detection using a scintillation counter may be employed. See, e.g., Larsson, 1988, Immunocytochemistry: Theory and Practice, (CRC Press, Boca Raton, FIa.); Methods in Molecular Biology, vol. 80 1998, John D. Pound (ed.) (Humana Press, Totowa, N. J.).

In certain embodiments, a molecule of interest (e.g., a biological molecule) is detected using a DNP-labeled nucleic acid polymer or protein, which is used to contact a cell or tissue sample, and an Fc-specific polymer- conjugated antibody signal-generating moiety conjugate that specifically binds DNP. In a variation of this embodiment, a molecule of interest is detected using a DNP labeled antibody that specifically recognizes a protein of interest in the cell or tissue, and an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate that specifically binds DNP.

In another embodiment, a protein of interest is bound by a monoclonal antibody that specifically recognizes the protein, and the monoclonal antibody is bound by an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate (e.g., Fc-specific PEGylated antibody signal-generating moiety conjugate) that specifically recognizes the host species of monoclonal antibody. For example, if the monoclonal antibody is raised in mouse or rabbit, then the Fc-specific polymer-conjugated antibody signal-generating moiety conjugate can be a goat-anti-mouse or goat-anti-rabbit antibody, respectively.

The Fc-specific polymer-conjugated antibody signal-generating moiety conjugate (e.g., Fc-specific PEGylated antibody signal-generating moiety conjugate)is suitable to detect the presence, amount, and/or localization of a biological molecule of interest and may be directly or indirectly detectable. Furthermore, many illustrative, non-limiting diagnostic examples exist, wherein the disclosed Fc-specific polymer-conjugated antibody signal- generating moiety conjugates (e.g., Fc-specific PEGylated antibody signal- generating moiety conjugates) may be used. For example, in one particular embodiment, a target molecule is bound by a DNP labeled nucleic acid polymer that is designed to specifically hybridize to the target DNA or RNA molecule(s) of interest. In a variation of this embodiment, a target molecule of interest is bound by a DNP labeled antibody that specifically recognizes the target protein of interest in the cell or tissue. The DNP-labeled reagents are then recognized (Ae., bound) by a rabbit anti- DNP monoclonal antibody, for example. The rabbit anti-DNP monoclonal antibody is then bound by a mouse anti-rabbit antibody, which in turn is bound by one or more disclosed Fc-specific polymer-conjugated antibody signal- generating moiety conjugates, wherein the conjugate is a goat anti-mouse Fc- specific polymer-conjugated antibody conjugated to biotin. A streptavidin or avidin labeled enzyme then contacts the conjugate and serves to indicate the presence, amount, and/or localization of the biological marker of interest in the presence of a suitable chromogenic or fluorogenic substrate. In a related embodiment, a directly detectable colloidal gold/streptavidin or avidin conjugate is used to visually indicate the presence, amount, and/or localization of the biological marker of interest. In another illustrative embodiment, a target molecule is bound by a hapten labeled nucleic acid polymer that is designed to specifically hybridize to the target DNA or RNA molecule(s) of interest. In a variation of this embodiment, a target molecule of interest is bound by a hapten labeled antibody that specifically recognizes the target protein of interest in the cell or tissue. The hapten-labeled reagents are then recognized (Ae., bound) by one or more disclosed Fc-specific polymer-conjugated antibody signal-generating moiety conjugates, wherein the conjugate is a goat or mouse anti-rabbit Fc- specific polymer-conjugated antibody conjugated to an enzyme {e.g., horseradish peroxidase or alkaline phosphatase), which serves to indicate the presence, amount, and/or localization of the biological marker of interest in the presence of a suitable chromogenic or fluorogenic substrate. In a related embodiment, the Fc-specific polymer-conjugated antibody signal-generating moiety conjugate is a goat or mouse anti-rabbit antibody that is conjugated to a signal-generating moiety that is directly detectable, such as colloidal gold particles in order to visually indicate the presence, amount, and/or localization of the biological molecule of interest.

One of ordinary skill in the art will also appreciate that automated stainers may be used in various embodiments of the invention, including embodiments which provide methods of detecting multiple biological molecules of interest. Detection of multiple biological molecules frequently requires balancing of the signals emanating from the different detectable substances. When multiple markers are to be detected it may thus be advantageous to provide different amplification conditions {i.e., varying numbers of binding reagents). Optimization of these conditions is well within the skill of one in the art.

The invention further provides kits for detecting a biological molecule in a sample, wherein the kits contain at least one Fc-specific polymer- conjugated antibody signal-generating moiety conjugate (e.g., Fc-specific PEGylated antibody signal-generating moiety conjugate) as described herein. In certain embodiments, the kit comprises 1 , 2, 3, 4, or 5 or more Fc-specific polymer-conjugated antibody signal-generating moiety conjugates (e.g., Fc-specific PEGylated antibody signal-generating moiety conjugates) comprising the same or any combination of signal generating moieties. In certain particular embodiments, the conjugates recognize the same biological molecule. In other embodiments, the conjugates recognize different biological molecules of a particular structure or cell type. Any or all of the conjugates may be labeled directly or indirectly as described herein throughout, and thus, indicate the presence, amount, and/or localization of the biological marker of interest.

In another embodiment, a kit may comprise an Fc-specific polymer-conjugated antibody signal-generating conjugate (e.g., Fc-specific PEGylated antibody signal-generating moiety conjugate), wherein the signal- generating moiety is biotin. In a related embodiment, the kit further comprises a streptavidin or avidin labeled enzyme, which then binds the biotinylated conjugate and serves to indicate the presence, amount, and/or localization of the biological marker of interest in the presence of a suitable chromogenic or fluorogenic substrate, as described herein throughout.

In a related embodiment, the kit may further comprise a colloidal gold/streptavidin or avidin detectable agent, which then binds the biotinylated conjugate and serves to indicate the presence, amount, and/or localization of the biological marker of interest in the presence of a suitable chromogenic or fluorogenic substrate, as described herein throughout.

In other various embodiments, a kit of the present invention comprises one or more Fc-specific polymer-conjugated antibody signal generating conjugates (e.g., Fc-specific PEGylated antibody signal-generating moiety conjugates), wherein the signal-generating moiety is an enzyme (e.g., HRP or AP) which then serves to indicate the presence, amount, and/or localization of the biological marker of interest in the presence of a suitable chromogenic or fluorogenic substrate, as described herein throughout. As used in this specification and the appended claims, the singular forms "a," "an" and "the" include plural references unless the content clearly dictates otherwise.

The practice of the present invention will employ, unless indicated specifically to the contrary, conventional methods of chemistry, biochemistry, organic chemistry, molecular biology, microbiology, recombinant DNA techniques, genetics, immunology, cell biology, stem cell protocols, cell culture and transgenic biology that are within the skill of the art, many of which are described below for the purpose of illustration. Such techniques are explained fully in the literature. See, e.g., Sambrook, et a/., Molecular Cloning: A

Laboratory Manual (3¹^ Edition, 2001); Sambrook, et al., Molecular Cloning: A Laboratory Manual (2ⁿd Edition, 1989); Maniatis et al., Molecular Cloning: A Laboratory Manual (1982); Ausubel et al., Current Protocols in Molecular Biology (John Wiley and Sons, updated July 2008); Short Protocols in Molecular Biology: A Compendium of Methods from Current Protocols in Molecular Biology, Greene Pub. Associates and Wiley-interscience; Glover, DNA Cloning: A Practical Approach, vol. I & Il (IRL Press, Oxford, 1985); Anand, Techniques for the Analysis of Complex Genomes, (Academic Press, New York, 1992); Guthrie and Fink, Guide to Yeast Genetics and Molecular Biology (Academic Press, New York, 1991 ); Oligonucleotide Synthesis (N. Gait, Ed., 1984); Nucleic Acid Hybridization (B. Hames & S. Higgins, Eds., 1985); Transcription and Translation (B. Hames & S. Higgins, Eds., 1984); Animal Cell Culture (R . Freshney, Ed., 1986); Perbal, A Practical Guide to Molecular Cloning (1984); Immobilized Cells And Enzymes (IRL Press, 1986); the treatise, Methods In Enzymology (Academic Press, Inc., N. Y.); Gene Transfer Vectors For Mammalian CeIIs [J. H. Miller and M. P. Calos eds., 1987, Cold Spring Harbor Laboratory); Harlow and Lane, Antibodies, (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1998); Immunochemical Methods In Cell And Molecular Biology (Mayer and Walker, eds., Academic Press, London, 1987); Handbook Of Experimental Immunology, Volumes I-IV (D. M. Weir and CC Blackwell, eds., 1986); Riott, Essential Immunology, 6th Edition, (Blackwell Scientific Publications, Oxford, 1988); All publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entireties. The various embodiments described herein can be combined to provide further embodiments. Further, aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications incorporated herein to provide yet further embodiments. Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be readily apparent to one of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims. The following examples are provided by way of illustration only and not by way of limitation. Those of skill in the art will readily recognize a variety of noncritical parameters that could be changed or modified to yield essentially similar results.

EXAMPLES EXAMPLE 1

PREPARATION OF A PEGYLATED ANTIBODY SIGNAL-GENERATING CONJUGATE

In one embodiment, a disclosed Fc-specific PEGyiated antibody signal-generating moiety conjugate is prepared according to the processes described in Schemes 1 to 4 below.

Synthesis of Fc-specific PEGylated Antibody

In one embodiment, the Fc portion an antibody is activated for conjugation and then conjugated to a PEG moiety as shown in Scheme 1 below. In Scheme 1 , a sugar moiety (located for example, in a glycosylated region of the Fc portion of the antibody) is first oxidized with a suitable oxidation reagent, such as sodium periodate (NaIO₄ ^"), to provide an aldehyde group. The aldehyde group is then reacted with an aldehyde-reactive group of the PEG derivative (such as the amine group of the illustrated amino-PEG derivative). The amination reaction produces a reversible Schiff base linkage that can then be reduced in a reductive amination reaction to a secondary amine group by using a suitable reducing agent such as sodium cyanoborohydride (NaBH₃CN). X represents -CH₂CH₂OCH₃ or -CH₂CH₂OH. The subscript n represents the number of sugar moieties, e.g., (C₆H₁₂Oe)_n=_I refers to a single sugar moiety. The subscript m represents the number of CH₂CH₂O monomer units (e.g., ethylene glycols) in the PEG chain, e.g., PEG_m=5o refers to a PEG polymer having 50 CH₂CH₂O monomer units or ethylene glycols. In particular embodiments m = 1 to 50, 2 to 30, 3 to 20, or 4 to 12. In preferred embodiments, the molecular weight of the PEG polymer itself is less than 2 kDa, less than 1.5 kDa, less than 1 kDa, or less than 500 D.

Scheme 1

Furthermore, although only a single amino-PEG derivative is shown to be conjugated to the Fc region of the antibody in Scheme 1 , it is possible, and in some embodiments preferred to conjugate 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more amino-PEG moieties to available aldehyde groups on the Fc portion of the antibody.

Synthesis of Signal-generating Moiety-PEG-maleimide Then, as shown in Scheme 2, a signal-generating moiety (such as an enzyme, e.g., horseradish peroxidase, alkaline phosphatase, and the like or a quantum dot) that has one or more available amine groups is reacted with an excess of a heterobifunctional polyalkylene glycol linker, which is a polyethylene glycol linker having an amine-reactive group (active ester) and a thiol-reactive group (maleimide). As shown in Scheme 2, reaction of the signal generating moiety and the linker form an activated signal-generating moiety. The subscript n represents the number of CH₂CH₂O monomer units (e.g., ethylene glycols) in the PEG chain. In particular embodiments, n=4, 8, or 12.

excess, R.T

Scheme 2

Reduction of Fc-specific PEGylated Antibody Thiol groups are introduced to the Fc-specific PEGylated antibody produced in Scheme 1 by treating the antibody with a reducing agent such as DTT as shown in Scheme 3. For a mild reducing agent such as DTE or DTT, a concentration of between about 1 mM and about 40 mM (for example, a concentration of between about 5 mM and about 30 mM or between about 15 mM and about 25 mM) is utilized to introduce a limited number of thiols (such as between about 2 and about 6) to the antibody while keeping the antibody intact (which can be determined by size-exclusion chromatography).

Reduction

Scheme 3

Although Schemes 2-3 illustrate an optimal process for conjugating maleimide PEG active esters, wherein the signal-generating moiety is first activated by reacting an amine group with the active ester of the linker to form an activated signal-generating moiety, it is also possible to first activate the antibody by reacting a thiol on the antibody with the linker and then react the activated antibody with the signal generating moiety (having an amine to react with the remaining reactive group on the linker).

The components produced according to Schemes 2 and 3 are then combined to give a conjugate as shown in Scheme 4.

Scheme 4

Furthermore, although only a single signal-generating moiety is shown to be conjugated to the Fc-specific PEGylated antibody (Scheme 4), it is possible, and in some embodiments preferred to conjugate 1 , 2, 3, or more signal generating moieties to available thiols on the Fc-specific PEGylated antibody.

In addition, it is possible to link multiple antibodies to a single signal-generating moiety or any number of signal-generating moieties to a single antibody.

EXAMPLE 2

PREPARATION OF FC-SPECIFIC PEGYLATED ANTIBODY HORSERADISH PEROXIDASE CONJUGATES

Materials

All chemicals used in the preparation of the Fc-specific PEGylated antibody HRP conjugates were purchased from commercial suppliers and used according to the manufacturers' protocols. Solutions of polyclonal antibody (goat anti-mouse and goat anti-rabbit) were purchased from Bethyl Labs, Inc. (Montgomery, TX). HRP was purchased from Pierce Biochemicals (Rockford, IL). Protein concentrations were calculated using ε₂βo values of 1.4 mL mg-1 cm-1 for the antibody and .625 mL mg-1 cm-1 for the HRP. Water was deionized and filtered through a Milli-Q® Biocel System to remove impurities. Buffer exchange was performed using Sephadex™ PD-10 desalting columns purchased from GE Biosciences (Piscataway, NJ). Size exclusion chromatography (SEC) was performed using an Akta™ Purifier purchased from GE Biosciences and molecular weights were referenced to protein standards. The flow rate was 1 mL/min through a Superdex™ 200 GL 10/300 column purchased from GE Biosciences.

Synthesis of Fc-specific PEGylated Polyclonal Antibody In order to oxidize the sugar moieties present in the Fc portion antibodies into reactive aldehyde groups, a solution of polyclonal antibody (e.g., goat anti-mouse and goat anti-rabbit) was prepared at a concentration of 3.0 mg/mL in a volume of 1.5 ml_. 65 μl_ of 100 mg/mL sodium periodate was added to the antibody solution to achieve a final periodate concentration of 100 mg/mL. The reaction solution was rotated for two hours and then passed through a Sephadex™ PD-10 desalting column (0.1 M sodium phosphate, 0.15M sodium chloride, pH = 7.5) to remove excess periodate. The amino-PEG derivative was added in a 500 molar excess relative to the antibody, which was followed by addition of 50 μmol (3.14 mg) of sodium cyanoborohydride. The reaction solution was rotated for 18 hours. Size exclusion chromatography (0.1 M sodium phosphate, 0.15M sodium chloride, pH = 7.5) was performed in order to purify the PEGylated antibody. The purified PEG derivatized antibody was concentrates 4-5 fold using a 30 kDa molecular weight cut-off Centricon™ device. The resulting solution was stored until use.

Synthesis of HRP-PEG Maleimide

HRP can, for example, be activated for conjugation by treatment with a 100-fold molar excess of a bifunctional discrete PEG (dPEG) linker having a maleimide group and an active ester group (for example, the MAL- dPEG₄™-NHS, MAL-dPEG₈™-NHS or MAL-dPEG₁₂™-NHS linkers available from Quanta Biodesign, Powell, OH) at ambient temperature (23 - 25 ⁰C) for 60 minutes. After purification across a Superdex™ 200 10/300 GL column, excess linker-free HRP, typically with five to seven maleimides, is obtained with a 100- fold molar excess. An exemplary procedure is outlined below for production of an HRP antibody conjugate using a MAL-dPEG₁₂™-NHS linker. The number of maleimide groups on an activated HRP can determined by the method described in detail in Example 4. HRP-OPEG₁₂-maleimide (1): HRP (Horseradish Peroxidase,

Pierce, Rockford, IL) was reconstituted from a lyophilized powder to a final concentration of 25 mg/mL solution (0.1 M sodium phosphate, 0.15M sodium chloride, pH = 7.5) in a 4 mL amber vial. 100 fold molar excess of MAL- dPEGi₂™ NHS ester (Quanta Biodesign, Powell, OH) was added to the HRP solution and the vial was then placed on an autorotator in the dark at ambient temperature (23 - 25⁰C), and the amide bond forming reaction was allowed to proceed for 1 hour. A 400 μL aliquot was then removed for purification, and the remainder of the solution was temporarily stored at 4⁰C. Pure HRP-dPEGi₂- maleimide was then obtained by fractionating the sample on an Akta™ Purifier fitted with a Superdex™ 10/300 column and eluted with a solution of 0.1 M sodium phosphate, 0.15M sodium chloride, pH 7.5 at 1.0 mL/min.

Synthesis of Thiolated Fc-specific PEGylated Antibody To activate an antibody for conjugation an anti-mouse IgG or anti- rabbit IgG antibody can be incubated, for example, with 25 mmol DTT at ambient temperature (23 - 25⁰C) for 25 minutes. After purification across a Sephadex™ PD-10 SE column, DTT-free PEGylated antibody, typically with two to six free thiols, is obtained (e.g., Scheme 3). The exemplary procedure outlined below for preparing goat anti-mouse PEGylated IgG thiol is generally applicable to other antibodies. The number of thiols per antibody can be determined by the thiol assay described in Example 4.

Goat anti-mouse Fc-specific PEGylated IgG-thiol (2): In order to thiolate the PEGylated IgG, 78.9 μL of a freshly prepared 500 mM DTT (1 ,4- Dithiothreitol, Sigma-Aldrich, St. Louis, MO) solution was added to 1.5 mL of concentrated Fc-specific PEGylated antibody solution as generated in the foregoing section entitled "Synthesis of Fc-specific PEGylated Polyclonal Antibody" in a 4 mL amber vial. The vial was placed in the dark on an autorotator and the disulfide reduction was allowed to proceed for 25 minutes. The reaction solution was split into four equal volumes (due to the limited capacity of a desalting column used), and excess DTT was removed by passing each of the fractions across a PD-10™ desalting column and eluting with a solution of 0.1 M sodium phosphate, 1.0 mM EDTA, pH 6.5. This thiolated Fc- specific PEGylated antibody was carried forward to the final conjugation step, described below. Synthesis of Fc-specific PEGylated Antibody HRP-PEG-MAL Conjugates

Purified HRP-dPEG-maleimide was added to purified, thiolated Fc-specific PEGylated antibody (such as anti-mouse Fc-specific PEGylated IgG-thiol, anti-mouse Fc-specific PEGylated IgM-thiol or anti-rabbit. Fc-specific PEGylated IgG-thiol), in a three fold molar excess. The reaction was incubated at ambient temperature (23 - 25°C) for 18 hours. After purification over a Superdex™ 200 10/300 GL SE column, a purified conjugate, typically with an average of 2 or 3 HRPs per antibody, is obtained. The number of HRPs per antibody is determined by measuring the ratio of absorbances at 280 nrm/403 nm of the conjugate, and performing the calculations outlined in section Example 4.

An exemplary procedure is outlined below. Goat-anti-mouse Fc-specific PEGylated IgG HRP-dPEG₁₂-MAL conjugate: One molar equivalent of the goat-anti-mouse Fc-specific PEGylated IgG-thiol (2) was combined with three molar equivalents of HRP-dPEGi₂- maleimide (1) in an amber vial. The vial was then placed on an autorotator in the dark at ambient temperature (23 - 25°C), and the Michael addition was allowed to proceed for 18 hours. Purified goat-anti-mouse Fc-specific PEGylated IgG HRP-dPEG-₁₂-MAL conjugate was then obtained by fractionating the sample on an Akta™ Purifier fitted with a Superdex™ 10/300 column and eluting with a solution of 0.1 M sodium phosphate, pH 7.5, at 0.9 mL/minute. The conjugate was then stored at 4°C until use.

EXAMPLE 3

IHC PERFORMANCE ASSESSMENT OF CONJUGATES AS SECONDARY ANTIBODIES TO

DIFFERENT PRIMARY ANTIBODIES

Goat anti-mouse Fc-specific PEGylated IgG HRP-PEG₁₂-MAL conjugate, goat anti-mouse Fc-specific PEGylated IgM HRP-PEG₁₂-MAL conjugate, goat anti-rabbit IgG Fc-specific PEGylated IgG HRP-PEG₁₂-MAL conjugate or a mixture of three conjugates ("amplification") was used as a secondary antibody reagent for detection of binding to tissue antigens of the primary antibodies that are listed below (available from Ventana Medical Systems, Inc, Tucson, AZ). Appropriate archival tissue sections were treated with these conjugates and developed using standard protocols for HRP signal generation (by addition of DAB) on an automated stainer (BenchMark^® XT, Ventana Medical Systems, Inc, Tucson, AZ). A typical automated protocol includes deparaffinization, several rinse steps, addition of a reaction buffer, addition of the primary antibody, addition of the secondary antibody, addition of DAB and hydrogen peroxide, and addition of a counterstain. Comparable (adjacent) tissue sections were stained with the disclosed conjugates or a mixture thereof and with non-Fc-PEGylated Antibody HRP-PEG-_I2-MAL conjugates (hereinafter "control conjugates") used as the secondary antibody reagent. Antibodies

Exemplary immunohistochemistry protocols are described below. Evaluation of Fc-specific PEGylated Antibody HRP-PEG-MAL conjugates I: Evaluation of the antibody staining for Ki-67 and Bcl-2 on tonsil; CD15 on Hodgkin's Lymphoma; Her2-neu and PR on breast; and S-100 on skin were conducted by an adapted procedure from the Ventana Benchmark

Instrument as follows. Paraffin sections of the above-mentioned tissues were transferred to slides and treated with EZPrep® and heated to remove the wax. Antigen retrieval was performed by addition of standard Cell Conditioner #1 (VMSI) alongside the application of a liquid cover slip (VMSI). Cell Conditioner #1 was re-applied every four minutes over the period of one hour, while the temperature was maintained at 100⁰C. The slide was subsequently rinsed and cooled to 37⁰C. Slides were treated for four minutes with 3% H₂O₂ solution to inhibit any native peroxidases. Primary antibody was applied to the slides and the slides were incubated for sixteen minutes. Slides were then rinsed. Fc- specific PEGylated antibody HRP-PEGi₂-MAL conjugates (e.g., secondary antibody) or control conjugates were applied to the slides and incubated for eight minutes. Slides were then rinsed. Next, the slides were incubated for four minutes with the chromagen-substrate DAB and 3% H₂O₂. Slides were then rinsed and incubated in a copper containing solution for four minutes. The slides received a final rinse and were then removed from the instrument and dehydrated. Slides were dehydrated by: i) rinsing the slides in water containing Dawn® dishwashing detergent to remove the liquid coverslip; ii) rinsing the slides in water; iii) soaking the slides for a period of two minutes in a series of alcohols, once in 80% ethanol, twice in 90% ethanol, three times in 100% ethanol; and iv) soaking the slides twice in xylene. Slides were then placed in an automatic coverslipper and coverslipped and subsequently viewed under a microscope.

Evaluation of Fc-specific PEGylated Antibody HRP-PEG-MAL conjugates II: Evaluation of the antibody staining for CD57 on tonsil was conducted by an adapted procedure from the Ventana Benchmark Instrument as follows. Paraffin sections of the above-mentioned tissues were transferred to slides and treated with EZPrep® and heated to remove the wax. The slide was subsequently rinsed and cooled to 37⁰C. Slides were treated for four minutes with 3% H₂O₂ solution to inhibit any native peroxidases. Antigen retrieval was performed by addition of a proteinase K (e.g., protease) solution for four minutes. Slides were then rinsed. Primary antibody was applied to the slides and the slides were incubated for sixteen minutes. Slides were then rinsed. Fc-specific PEGylated antibody HRP-PEGi₂-MAL conjugates (e.g., secondary antibody) or control conjugates were applied to the slides and incubated for eight minutes. Slides were then rinsed. Next, the slides were incubated for four minutes with the chromagen-substrate DAB and 3% H₂O₂. Slides were then rinsed and incubated in a copper containing solution for four minutes. The slides received a final rinse and were then removed from the instrument and dehydrated. Slides were dehydrated by: i) rinsing the slides in water containing Dawn® dishwashing detergent to remove the liquid coverslip; ii) rinsing the slides in water; iii) soaking the slides for a period of two minutes in a series of alcohols, once in 80% ethanol, twice in 90% ethanol, three times in 100% ethanol; and iv) soaking the slides twice in xylene. Slides were then placed in an automatic coverslipper and coverslipped and subsequently viewed under a microscope.

Experiments described herein also included negative control slides which omitted the application of the primary antibody in favor of Antibody Diluent Solution (VMSI). The remainder of the IHC protocol was unaltered.

IHC Results

FIG. 1 shows the results of an HRP-DAB staining for anti-Ki-67 antibody detection in tonsil sections. Goat-anti-mouse Fc-specific PEGylated IgG HRP-PEG₁₂-MAL conjugates at a concentration of 45 μg/mL (FIG. 1A) or non-PEGylated goat-anti-mouse IgG HRP-PEG₁₂-MAL conjugates (e.g., control conjugates) at a concentration of 30 μg/mL (FIG. 1 B) were used to detect the anti-Ki-67 antibody. The results demonstrate that higher intensity staining with lower overall background staining (Ae., higher specificity) is achieved with the Fc-specific PEGylated antibody signal-generating moiety conjugate in comparable tissue sections.

FIG. 2 shows the results of an HRP-DAB staining for anti-CD15 antibody detection in Hodgkin's Lymphoma sections. Goat-anti-mouse Fc- specific PEGylated IgM HRP-PEG₁₂-MAL conjugates at a concentration of 14 μg/mL (FIG. 2A) or non-PEGylated goat-anti-mouse IgM HRP-PEG₁₂-MAL conjugates (e.g., control conjugates) at a concentration of 6 μg/mL (FIG. 2B) were used to detect the anti-CD15 antibody. The results demonstrate that higher intensity staining with lower overall background staining (i.e., higher specificity) is achieved with the Fc-specific PEGylated antibody signal- generating moiety conjugate in comparable tissue sections. FIG. 3 shows the results of an HRP-DAB staining for anti-CD20 antibody detection in tonsil sections. Goat-anti-mouse Fc-specific PEGylated IgG HRP-PEG₁₂-MAL conjugates at a concentration of 45 μg/mL (FIG. 3A) or non-PEGylated goat-anti-mouse IgG HRP-PEG₁₂-MAL conjugates (e.g., control conjugates) at a concentration of 30 μg/mL (FIG. 3B) were used to detect the anti-CD20 antibody. The results demonstrate that higher intensity staining with lower overall background staining (i.e., higher specificity) is achieved with the Fc-specific PEGylated antibody signal-generating moiety conjugate in comparable tissue sections. FIG. 4 shows the results of HRP-DAB staining for anti-CD15 antibody in tonsil sections. Images of anti-CD15 staining in tonsil tissue sections were generated at 1 OX magnification and stained using a cocktail of goat-anti-mouse Fc-specific PEGylated IgM HRP-PEG₁₂-MAL conjugate (12 μg/mL), goat-anti-mouse Fc-specific PEGylated IgG HRP-PEG₁₂-MAL conjugate (50 μg/mL), and goat-anti-rabbit Fc-specific PEGylated IgG HRP- PEG-₁₂-MAL conjugate (60 μg/mL). The HRP signal was developed using hydrogen peroxide and DAB as the chromogenic stain. The tonsil tissue stained in panels A and B received the conjugate cocktail, but the tissue in panel A received no primary antibody application. The tonsil tissue stained in panels C and D received the non-PEGylated control conjugates, but the tissue in panel C received no primary antibody application. A comparison of panel A and panel C demonstrates that usage of the conjugate cocktail results in reduced background staining. A comparison of panel B and panel D demonstrates that staining with the conjugate cocktail results in both higher intensity staining for anti-CD15 antibody with a lower overall background staining.

FIG. 5 shows the results of HRP-DAB staining for anti-CD57 antibody in tonsil sections. Images of anti-CD57 staining in tonsil tissue sections were generated at 10X magnification and stained using a cocktail of goat-anti-mouse Fc-specific PEGylated IgM HRP-PEG₁₂-MAL conjugate (12 μg/mL), goat-anti-mouse Fc-specific PEGylated IgG HRP-PEG₁₂-MAL conjugate (50 μg/mL), and goat-anti-rabbit Fc-specific PEGylated IgG HRP- PEG₁₂-MAL conjugate (60 μg/mL). The HRP signal was developed using hydrogen peroxide and DAB as the chromogenic stain. The tonsil tissue stained in panels A and B received the conjugate cocktail, but the tissue in panel A received no primary antibody application. The tonsil tissue stained in panels C and D received the non-PEGylated control conjugates, but the tissue in panel C received no primary antibody application. A comparison of panel A and panel C demonstrates that usage of the conjugate cocktail results in reduced background staining. A comparison of panel B and panel D demonstrates that staining with the conjugate cocktail results in both higher intensity staining for anti-CD57 antibody with a lower overall background staining.

FIG. 6 shows the results of HRP-DAB staining for anti-Her2-neu antibody in breast tissue sections. Images of anti-Her2-neu staining in breast tissue sections were generated at 10X magnification and stained using a cocktail of goat-anti-mouse Fc-specific PEGylated IgM HRP-PEG₁₂-MAL conjugate (12 μg/mL), goat-anti-mouse Fc-specific PEGylated IgG HRP-PEG-₁₂- MAL conjugate (50 μg/mL), and goat-anti-rabbit Fc-specific PEGylated IgG HRP-PEG-₁₂-MAL conjugate (60 μg/mL). The HRP signal was developed using hydrogen peroxide and DAB as the chromogenic stain. The breast tissue stained in panels A and B received the conjugate cocktail, but the tissue in panel A received no primary antibody application. The breast tissue stained in panels C and D received the non-PEGylated control conjugates, but the tissue in panel C received no primary antibody application. A comparison of panel A and panel C demonstrates that usage of the conjugate cocktail results in reduced background staining. A comparison of panel B and panel D demonstrates that staining with the conjugate cocktail results in both higher intensity staining for anti-Her2-neu antibody with a lower overall background staining. FIG. 7 shows the results of HRP-DAB staining for anti-Ki-67 antibody in tonsil sections. Images of anti-Ki67 staining in tonsil tissue sections were generated at 1 OX magnification and stained using a cocktail of goat-anti- mouse Fc-specific PEGylated IgM HRP-PEG₁₂-MAL conjugate (12 μg/mL), goat-anti-mouse Fc-specific PEGylated IgG HRP-PEG₁₂-MAL conjugate (50 μg/mL), and goat-anti-rabbit Fc-specific PEGylated IgG HRP-PEG₁₂-MAL conjugate (60 μg/mL). The HRP signal was developed using hydrogen peroxide and DAB as the chromogenic stain. The tonsil tissue stained in panels A and B received the conjugate cocktail, but the tissue in panel A received no primary antibody application. The tonsil tissue stained in panels C and D received the non-PEGylated control conjugates, but the tissue in panel C received no primary antibody application. A comparison of panel A and panel C demonstrates that usage of the conjugate cocktail results in reduced background staining. A comparison of panel B and panel D demonstrates that staining with the conjugate cocktail results in both higher intensity staining for anti-Ki-67 antibody with a lower overall background staining. FIG. 8 shows the results of HRP-DAB staining for anti-PR

(progesterone receptor) antibody in breast tissue sections. Images of anti-PR staining in breast tissue sections were generated at 10X magnification and stained using a cocktail of goat-anti-mouse Fc-specific PEGylated IgM HRP- PEG-₁₂-MAL conjugate (12 μg/mL), goat-anti-mouse Fc-specific PEGylated IgG HRP-PEG-₁₂-MAL conjugate (50 μg/mL), and goat-anti-rabbit Fc-specific

PEGylated IgG HRP-PEG₁₂-MAL conjugate (60 μg/mL). The HRP signal was developed using hydrogen peroxide and DAB as the chromogenic stain. The breast tissue stained in panels A and B received the conjugate cocktail, but the tissue in panel A received no primary antibody application. The breast tissue stained in panels C and D received the non-PEGylated control conjugates, but the tissue in panel C received no primary antibody application. A comparison of panel A and panel C demonstrates that usage of the conjugate cocktail results in reduced background staining. A comparison of panel B and panel D demonstrates that staining with the conjugate cocktail results in both higher intensity staining for anti-PR antibody with a lower overall background staining. In conclusion, the results of tissue testing of the Fc-specific PEGylated antibody HRP-PEGi₂-MAL conjugates demonstrate that the conjugates significantly out-perform non-PEGylated control conjugates for tissue staining. The Fc-specific PEGylated antibody HRP-PEG₁₂-MAL conjugates result in significantly higher signal intensity along with significantly reduced non-specific background staining.

In the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.

Claims

1. A method for detecting a molecule of interest in a biological sample, comprising:

(a) contacting the biological sample with an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate that binds to the molecule of interest; and

(b) detecting a signal generated by the Fc-specific polymer- conjugated antibody signal-generating moiety conjugate that indicates the presence of the molecule of interest in the sample; wherein said polymer is hydrophilic and non-immunogenic.

2. The method of claim 1 , wherein the polymer comprises a homopolymer selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone), and polyethylene glycol.

3. The method of claim 1 , wherein the polymer comprises a heteropolymer comprising at least one monomeric subunit from two or more of the polymers selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone), and polyethylene glycol .

4. The method of claim 1 , wherein the polymer is polyethylene glycol.

5. The method of claim 1 , wherein the signal-generating moiety is selected from the group consisting of fluorescent labels, enzyme labels, radioisotopes, chemiluminescent labels, electrochemiluminescent labels, bioluminescent labels, polymers, polymer particles, quantum dots, metal particles, haptens and dyes.

6. The method of claim 1 , wherein the signal generating moiety comprises an enzymatic label.

7. The method of claim 6, wherein the enzymatic label is horseradish peroxidase or alkaline phosphatase.

8. The method of claim 1 , wherein the signal generating moiety comprises a hapten.

9. The method of claim 8, wherein the hapten is biotin.

10. The method of claim 9, wherein detecting said signal further comprises the addition of streptavidin- horseradish peroxidase, avidin- horseradish peroxidase, streptavidin-alkaline phosphatase, avidin- alkaline phosphatase, streptavidin-colloidal gold or avidin-colloidal gold.

11. A method for detecting a molecule of interest in a biological sample, comprising:

(a) contacting the biological sample with a primary antibody that binds to the molecule of interest;

(b) contacting the sample of step (a) with an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate that binds to the primary antibody; and

(c) detecting a signal generated by the Fc-specific polymer- conjugated antibody signal-generating moiety conjugate that indicates the presence of the molecule of interest in the sample; wherein said polymer is hydrophilic and non-immunogenic.

12. The method of claim 11 , wherein the polymer comprises a homopolymer selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone) and polyethylene glycol.

13. The method of claim 11 , wherein the polymer comprises a heteropolymer comprising at least one monomeric subunit from two or more of the polymers selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone) and polyethylene glycol.

14. The method of claim 11 , wherein the polymer is polyethylene glycol.

15. The method of claim 11 , wherein the primary antibody is comprises hapten.

16. The method of claim 11 , wherein the signal-generating moiety is selected from the group consisting of fluorescent labels, enzyme labels, radioisotopes, chemϋuminescent labels, electrochemiluminescent labels, bioluminescent labels, polymers, polymer particles, quantum dots, metal particles, haptens and dyes.

17. A method for detecting a molecule of interest in a biological sample, comprising:

(a) contacting the biological sample with a labeled nucleic acid probe that binds to the molecule of interest;

(b) contacting the sample of step (a) with an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate that binds to the labeled nucleic acid probe; and

18. The method of claim 17, wherein the polymer comprises a homopolymer selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone) and polyethylene glycol.

19. The method of claim 17, wherein the polymer comprises a heteropolymer comprising at least one monomeric subunit from two or more of the polymers selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone) and polyethylene glycol.

20. The method of claim 17, wherein the polymer is polyethylene glycol.

21. The method of claim 17, wherein the nucleic acid label comprises hapten.

22. The method of claim 17, wherein the signal-generating moiety is selected from the group consisting of fluorescent labels, enzyme labels, radioisotopes, chemiluminescent labels, electrochemiluminescent labels, bioluminescent labels, polymers, polymer particles, quantum dots, metal particles, haptens and dyes.

23. The method according to any one of claims 1-22, wherein the biological sample comprises a urine, blood, sera, sputum, tissue or cellular sample.

24. The method according to any one of claims 1-22, wherein the method is an in situ hybridization, immunohistochemistry, immunocytochemistry, flow cytometry, enzyme immuno-assay or enzyme linked immuno-assay method.

25. An Fc-specific polymer-conjugated antibody signal- generating moiety conjugate comprising:

(a) one or more derivatives of hydrophilic, non- immunogenic polymers covalently bound to oligosaccharide moieties in a glycosylated region of the Fc portion of an antibody; and

(b) one or more signal-generating moieties covalently bound to the antibody via moieties other than said polymers.

26. The conjugate of claim 25, wherein the one or more derivatives of hydrophilic, non-immunogenic polymers comprise homopolymers selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone) and polyethylene glycol.

27. The conjugate of claim 25, wherein the one or more derivatives of hydrophilic, non-immunogenic polymers comprise heteropolymers comprising at least one monomeric subunit from two or more of the polymers selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone) and polyethylene glycol.

28. The conjugate of claim 25, wherein the one or more derivatives of hydrophilic, non-immunogenic polymers are polyethylene glycol derivatives.

29. The conjugate of claim 28, wherein the polyethylene glycol derivatives are covalently bound to aldehyde groups in the glycosylated region of the Fc portion of the antibody.

30. The conjugate of any one of claims 25-29, wherein the one or more signal generating moieties are thiol reactive signal-generating moieties covalently bound to a thiol group formed on the antibody.

31. The conjugate of claim 29, wherein the polyethylene glycol (PEG) derivatives have the formula:

Y-A-PEG_m-B-X

wherein Y comprises a nucleophilic group selected from the group consisting of an amino group, a hydrazide group, a carbohydrazide group, a semicarbazide group, a thiosemicarbazide group, a thiocarbazide group, a carbonic acid dihydrazine group, and a hydrazine carboxylate group; wherein X comprises -CH₂CH₂OCH₃ or -CH₂CH₂OH; wherein the subscript m = 1 to 50; and wherein A and B each independently comprise from 0 to 10 carbon atoms.

32. The conjugate of claim 25, wherein the molecular weight of the each of the one or more polymers is less than 2 kDa.

33. The conjugate of claim 25, wherein the molecular weight of the each of the one or more polymers is less than 1.5 kDa.

34. The conjugate of claim 25, wherein the molecular weight of the each of the one or more polymers is less than 1 kDa.

35. The conjugate of claim 25, wherein the molecular weight of the each of the one or more polymers is less than 0.5 kDa.

36. The conjugate of claim 30, wherein each of the one or more thiol reactive signal-generating moieties comprises a discrete polyethylene glycol linker that has a chain length selected from the group consisting of 4 monomeric polyethylene glycol units, 8 monomeric polyethylene glycol units and 12 monomeric polyethylene glycol units.

37. The conjugate of claim 25, wherein the signal-generating moiety is selected from the group consisting of fluorescent labels, enzyme labels, radioisotopes, chemiluminescent labels, electrochemiluminescent labels, bioluminescent labels, polymers, polymer particles, quantum dots, metal particles, haptens and dyes.

38. The conjugate of claim 37, wherein the signal generating moiety comprises an enzymatic label.

39. The conjugate of claim 38, wherein the enzymatic label is horseradish peroxidase or alkaline phosphatase.

40. The conjugate of claim 37, wherein the signal generating moiety comprises a hapten.

41. The conjugate of claim 40, wherein the hapten is biotin.

42. The conjugate of claim 25, wherein the antibody is a monoclonal antibody.

43. The conjugate of claim 25, wherein the antibody is a polyclonal antibody.

44. A method for preparing an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate, comprising:

(a) reacting an antibody with an oxidant to form reactive aldehyde groups in a glycosylated region of the Fc-portion of the antibody; (b) reacting the aldehyde group bearing antibody with a nucleophilic derivative of a hydrophilic, non-immunogenic polymer to form an antibody-polymer intermediate;

(c) stabilizing the antibody-polymer intermediate to form an Fc-specific polymer-conjugated antibody;

(d) forming a thiolated Fc-specific polymer-conjugated antibody;

(e) forming a thiol reactive signal-generating moiety; and

(f) reacting the thiolated Fc-specific polymer conjugated antibody of step (d) with the thiol reactive signal-generating moiety of step (e); thereby forming an Fc-specific polymer-conjugated antibody signal-generating moiety conjugate.

45. The method of claim 44, wherein the nucleophilic derivative of a hydrophilic, non-immunogenic polymer comprises a homopolymer selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone) and polyethylene glycol.

46. The method of claim 44, wherein the nucleophilic derivative of a hydrophilic, non-immunogenic polymer comprises a heteropolymer comprising at least one monomeric subunit from two or more of the polymers selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone) and polyethylene glycol.

47. The method of claim 44, wherein the nucleophilic derivative of a hydrophilic, non-immunogenic polymer is a polyethylene glycol derivative.

48. The method of claim 44, wherein the oxidant is selected from the groups consisting of pehodates, galatose oxidase, or a combination thereof.

49. The method of claim 48, wherein the oxidant is sodium period ate.

50. The method of claim 44, wherein 1 to 10 aldehyde groups are formed.

51. The method of claim 44, wherein 4 to 7 aldehyde groups are formed.

52. The method of claim 44, wherein 3 to 5 aldehyde groups are formed.

53. The method of claim 44, wherein the molecular weight of the polymer is less than 2 kDa.

54. The method of claim 44, wherein the molecular weight of the polymer is less than 1.5 kDa.

55. The method of claim 44, wherein the molecular weight of the polymer is less than 1 kDa.

56. The method of claim 44, wherein the molecular weight of the polymer is less than 0.5 kDa.

57. The method of claim 44, wherein each of the one or more thiol reactive signal-generating moieties comprises a discrete polyethylene glycol linker that has a chain length selected from the group consisting of 4 monomeric polyethylene glycol units, 8 monomeric polyethylene glycol units and 12 monomeric polyethylene glycol units.

58. The method of claim 47, wherein the polyethylene glycol (PEG) derivative has the formula:

Y-A-PEG_m-B-X

wherein Y comprises a nucleophilic group selected from the group consisting of: an amino group, a hydrazide group, a carbohydrazide group, a semicarbazide group, a thiosemicarbazide group, a thiocarbazide group, a carbonic acid dihydrazine group, and a hydrazine carboxylate group; wherein X comprises -CH₂CH₂OCH₃ or -CH₂CH₂OH; wherein the subscript m = 1 to 50; and wherein A and B each independently comprise from 0 to 10 carbon atoms.

59. The method of claim 47, wherein the antibody- polyethylene glycol intermediate is stabilized by reacting the antibody- polyethylene glycol intermediate with a reducing agent.

60. The methods of claim 59, wherein reacting the antibody- polyethylene glycol intermediate with the reducing agent results in reductive amination of the antibody- polyethylene glycol intermediate.

61. The method of claim 60, wherein the reductive amination is accomplished by treating the antibody- polyethylene glycol intermediate with sodium cyanoborohydride, sodium thacetoxyborohydride or an amine borane.

62. The method of claim 47, wherein forming the thiolated Fc- specific polymer-conjugated antibody comprises reacting the Fc-specific polymer-conjugated antibody with a reducing agent to form the thiol groups on the Fc-specific polymer-conjugated antibody.

63. The method of claim 62, wherein the average number of thiol groups per Fc-specific polymer-conjugated antibody is between about 1 and about 10.

64. The method of claim 62, wherein the reducing agent is selected from the group consisting of 2-mercaptoethanol, 2- mercaptoethylamine, dithiothreitol, dithioerythritol and tris(carboxyethy!)phosphine, and combinations thereof.

65. The method of claim 64, wherein reducing agent is selected from the group consisting of dithioerythritol and dithioerythritol , and combinations thereof.

66. The method of claim 62, wherein the reducing agent is reacted at a concentration of between about 1 mM and about 40 mM.

67. The method of claim 47, wherein forming the thiolated Fc- specific polymer-conjugated antibody comprises introducing a thiol group to the Fc-specific polymer-conjugated antibody.

68. The method of claim 67, wherein the thiol group is introduced to the Fc-specific polymer-conjugated antibody by reacting the Fc- specific polymer-conjugated antibody with a reagent selected from the group consisting of 2-iminothiolane, N-succinimidyl S-acetylthioacetate, succinimidyl acetyl-thiopropionate, N-succinimidyl 3-(2-pyridyldithio)propionate, N- acetylhomocysteinethiolactone, S-acetylmercaptosuccinic acid and cystamine, and combinations thereof.

69. The method of claim 44, wherein forming a thiol reactive signal-generating moiety comprises reacting a signal generating moiety with a maleimide ester, wherein the maleimide ester comprises an amine-reactive ester group and a thiol-reactive maleimide group, and wherein the maleimide and ester groups are linked by a heterobifunctional polyalkylene glycol linker.

70. The method of claim 69, wherein the polyalkylene glycol linker is a discrete polyethylene glycol.

71. The method of claim 70, wherein the discrete polyethylene glycol has a chain length selected from the group consisting of 4 monomeric polyethylene glycol units, 8 monomeric polyethylene glycol units and 12 monomeric polyethylene glycol units.

72. The method of claim 44, wherein the signal-generating moiety is selected from the group consisting of fluorescent labels, enzyme labels, radioisotopes, chemiluminescent labels, electrochemiluminescent labels, bioluminescent labels, polymers, polymer particles, quantum dots, metal particles, haptens and dyes.

73. The method of claim 72, wherein the signal generating moiety comprises an enzymatic label.

74. The method of claim 73, wherein the enzymatic label is horseradish peroxidase or alkaline phosphatase.

75. The method of claim 72, wherein the signal generating moiety comprises a hapten.

76. The method of claim 75, wherein the hapten is biotin.

77. The method of claim 44, wherein the antibody is a monoclonal antibody.

78. The method of claim 44, wherein the antibody is a polyclonal antibody.

79. A kit for detecting a molecule of interest in a biological sample, comprising an Fc-specific polymer-conjugated antibody signal- generating moiety conjugate, wherein said polymer is hydrophilic and non- immunogenic.

80. The kit of claim 79, wherein the polymer comprises a homopolymer selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone) and polyethylene glycol.

81. The kit of claim 79, wherein the hydrophilic, non- immunogenic polymer comprises a heteropolymer comprising at least one monomeric subunit from two or more of the polymers selected from the group consisting of polyvinyl alcohol), poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), polyvinyl pyrrolidinone) and polyethylene glycol.

82. The kit of claim 79, wherein the hydrophilic, non- immunogenic polymer is polyethylene glycol.

83. The kit of claim 79, wherein the signal-generating moiety is selected from the group consisting of fluorescent labels, enzyme labels, radioisotopes, chemiluminescent labels, electrochemiluminescent labels, bioluminescent labels, polymers, polymer particles, quantum dots, metal particles, haptens and dyes.

84. The kit of claim 79, wherein the signal generating moiety comprises a hapten.

85. The kit of claim 84, wherein the hapten is biotin.

86. The kit of claim 79, wherein the kit further comprises streptavidin-horseradish peroxidase, avidin-horseradish peroxidase, streptavidin-alkaline phosphatase, avidin-alkaline phosphatase, streptavidin- colloidal gold, or avidin-colloidal gold.