NZ618046B2 - Fc RECEPTOR BINDING PROTEINS - Google Patents

Abstract

Disclosed is an isolated antibody comprising a light chain variable region (VL) and a heavy chain variable region (VH), wherein the antibody binds to human FcRn; and wherein the VL comprises: (i) a VL CDR1 comprising the amino acid sequence TGTGSDVGSYNLVS (SEQ ID NO: 14); (ii) a VL CDR2 comprising the amino acid sequence GDSQRPS (SEQ ID NO: 15); and (iii) a VL CDR3 comprising the amino acid sequence SSYAGSGIYV (SEQ ID NO: 12) or ASYAGSIYV (SEQ ID NO: 13); and the VH comprises: (i) a VH CDR1 comprising the amino acid sequence EYAMG (SEQ ID NO: 22); (ii) a VH CDR2 comprising the amino acid sequence SIGSSGGQTKYADSVKG (SEQ ID NO: 23); and (iii) a VH CDR3 comprising the amino acid sequence LAIGDSY (SEQ ID NO: 24). Further disclosed is the use of said antibody in the manufacture of a medicament for modulating an FcRn activity or for treating an autoimmune disorder. ng the amino acid sequence GDSQRPS (SEQ ID NO: 15); and (iii) a VL CDR3 comprising the amino acid sequence SSYAGSGIYV (SEQ ID NO: 12) or ASYAGSIYV (SEQ ID NO: 13); and the VH comprises: (i) a VH CDR1 comprising the amino acid sequence EYAMG (SEQ ID NO: 22); (ii) a VH CDR2 comprising the amino acid sequence SIGSSGGQTKYADSVKG (SEQ ID NO: 23); and (iii) a VH CDR3 comprising the amino acid sequence LAIGDSY (SEQ ID NO: 24). Further disclosed is the use of said antibody in the manufacture of a medicament for modulating an FcRn activity or for treating an autoimmune disorder.

Description

Fc RECEPTOR BINDING PROTEINS RELATED ATIONS This application claims priority under 35 U.S.C. §ll9 to United States ional Application No. 6l/492,6l7, filed June 2, 2011, and Provisional Application No. 61/498,266, filed June 17, 2011. The entire contents of both provisional applications are herein incorporated by reference in their entirety.

FIELD OF THE INVENTION The field of invention relates to ns that bind the Fc receptor.

BACKGROUND OF THE INVENTION The most abundant antibody isotype in the serum is IgG and it has a critical role in mediating protection against pathogens as well as in mediating allergic and inflammatory responses that hasten recruitment of immune system components to the s, mucosae, and dermal es (Junghans, Immunologic Research 29 (1997)). Moreover, it is also a key component of a variety of autoimmune diseases. Under normal ions, the halflife of IgG in the serum is in the range of 5—7 days in mice and 22—23 days in humans, which is a prolonged , relative to the serum half life of other plasma proteins. In part, this occurs because the neonatal FcRn receptor (FcRn) rescues pinocytosed IgG from degradative lysosomes and es it back to the extracellular compartment (Junghans and Anderson, Proc. Natl. Acad. Sci. USA 93:5512 (1996), Roopenian et al. J. Immunology 170:3528 (2003)).

FcRn binds to the the Fc portion of IgG. The interaction between the IgG Fc region and FcRn is pH—dependent. Upon entry into cells by fluid phase endocytosis, IgG is sequestered into endosomes and binds to FcRn with high affinity at acidic pH (6~6.5); when the Rn complex cycles to the plasma membrane, IgG dissociates rapidly from FcRn in the bloodstream at slightly basic pH (~7.4). By this receptor—mediated ing ism, FcRn effectively rescues the IgG from degradation in lysosomes, thereby prolonging the half— life of circulating IgG.

FcRn is a non—covalent heterodimer that typically resides in the endosomes of endothelial and epithelial cells. It is a membrane bound receptor with a single—pass transmembrane having three heavy chain alpha domains ((11, 0L2, and 0L3) and a single soluble light chain B2—microglobulin (B2M) domain. Structurally, it belongs to a family of major histocompatibility complex class 1 molecules that have B2M as a common light chain. The FcRn or chain is a 46 kD protein composed of an ellular domain containing the (11, 0L2, and 0L3 heavy chain domains, a transmembrane , and a relatively short cytoplasmic tail (Burmeister et al. Nature 372:366 (1994)).

FcRn was first identified in the neonatal rat gut, where it functions to mediate the absorption of IgG antibody from the mother’s milk and facilitates its transport to the circulatory system (Leach et al. J Immunol 157:3317 (1996)). FcRn has also been isolated from human placenta, where it also mediates absorption and transport of maternal IgG to the fetal circulation. In adults, FcRn is expressed in a number of tissues, ing epithelial tissues of the lung, instestine, , as well as nasal, vaginal, and biliary tress surfaces (US. Patent Nos. 6,030,613 and 6,086,875; Israel et al. Immunology 92:69 (1997); Kobayashi et al. Am J Physiol ; Renal Physiol 282:F358 (2002)).

In order to study the contributions of FcRn to IgG homeostasis, mice have been engineered so that at least part of the genes encoding B2M and FcRn heavy chains have been “knocked out” so that these proteins are not expressed (WO 02/43658; ns and Anderson, Proc Natl Acad Sci US 93:5512 (1996)). In these mice, the serum ife and concentrations of IgG were dramatically reduced, suggesting a FcRn dependent mechanism for IgG homeostasis.

It has also been suggested that anti—human FcRn antibodies may be ted in these FcRn knockout mice and that these dies may prevent the binding of IgG to FcRn.

However, such dies have not been generated or tested (WO 02/43658).

The inhibition of IgG binding to FcRn negatively alters IgG serum half—life by preventing IgG recycling. This principle has been shown to be therapeutically effective in a mouse model of autoimmune ous bullous diseases (Li et al. J Clin Invest 115:3440— 3450 (2005)). Accordingly, agents that block or antagonize the binding of IgG to FcRn may be used in a method to treat or prevent autoimmune and inflammatory diseases or disorders terized by the presence of inappropriately regulated IgG antibodies. An antagonistic anti—rat FcRn monoclonal antibody (mAb)lG3 successfully prevented Experimental Autoimmune Myasthenia Gravis (EAMG) in a rat passive model at a dose of 30 mg/kg; that is about 100 fold lower than the intraveneous IgG (IVIG) used in treatment of MG, SLE, and WO 67039 ITP. Further, FcRn—deficient mice genetically predisposed to develop autoimmune disorder such as lupus or arthritis have icant reduction in severity of the disease.

SUMMARY OF THE INVENTION The t disclosure provides isolated antibodies that bind the human Fc receptor, nucleic acids encoding such antibodies, and methods of using these antibodies to detect presence of FcRn, modulate Fc receptor activity, and treat autoimmune disorders.

Accordingly, one aspect of the t disclosure features an isolated antibody that binds to human FcRn. This anti—FcRn antibody comprises a light chain variable region (VL) that comprises a VL CDRl, a VL CDR2 and a VL CDR3 region, wherein the VL CDR3 region has at least 85% (e. g., 90% or 95%) gy with the VL CDR3 region of SSYAGSGIYV (SEQ ID NO: 12) or ASYAGSGIYV (SEQ ID NO: 13). Optionally, the VL CDRl and VL CDR2 of the anti—FcRn antibody have at least 85% (e. g., at least 90% or 95%) gy with the VL CDRl region TGTGSDVGSYNLVS (SEQ ID NO: 14) and VL CDR2 region GDSQRPS (SEQ ID NO: 15), respectively. The anti—FcRn antibody does not have a cysteine at the first position of at least one CDR3 region, e.g., at least one of the VL CDR3 regions.

In some embodiments, the above—described anti—FcRn antibody ses a VL CDRl having at least 90% homology with VGSYNLVS (SEQ ID NO: 14), a VL CDR2 having at least 90% homology with GDSQRPS (SEQ ID , and/or a VL CDR3 having at least 90% homology with SSYAGSGIYV (SEQ ID NO: 12) or ASYAGSGIYV (SEQ ID NO: 13). In one example, the anti—FcRn antibody comprises the VL CDRl region TGTGSDVGSYNLVS (SEQ ID NO: 14), the VL CDR2 region GDSQRPS (SEQ ID NO:15), and/or the VL CDR3 region SSYAGSGIYV (SEQ ID NO: 12) or ASYAGSGIYV (SEQ ID NO: 13).

In other embodiments, the isolated anti—FcRn antibody disclosed herein ses a VL that comprises an amino acid sequence having at least 85% (e. g., at least 90%, 95% or 98%) homology with SEQ ID NO: 10 or SEQ ID NO:ll. In one example, the VL of the isolated antibody comprises the amino acid sequence of SEQ ID NO: 10 or SEQ ID NO:ll.

Another aspect of the present sure features an isolated anti—FcRn antibody comprising a light chain variable region (VL) that comprises a VL CDRl, a VL CDR2 and a VL CDR3 region, wherein the VL CDR3 region has up to 3 amino acid substitutions as compared to the following sequence: SSYAGSGIYV (SEQ ID NO: 12) or ASYAGSGIYV (SEQ ID NO: 13), and wherein the ed antibody does not have a cysteine at the first position of at least one CDR3 region e.g., at least one of the VL CDR3 regions. Optionally, the VL CDRl, VL CDR2 and VL CDR3 of the anti—FcRn antibody, tively, contain up to amino acid tutions as compared to the ing sequences (a) CDRl: TGTGSDVGSYNLVS (SEQ ID NO:l4) (b) CDR2: GDSQRPS (SEQ ID NO:15) (c) CDR3: SSYAGSGIYV (SEQ ID NO: 12), or GIYV (SEQ ID NO: 13).

Any of the anti—FcRn antibodies described above can further comprise a heavy chain variable region (VH) that comprises a VH CDRl, a VH CDR2, and a VH CDR3, wherein the VH CDR3 has at least 85% (e.g., at least 90% or 95%) homology with LAIGDSY (SEQ ID NO:24). Optionally, the VH CDRl and VH CDR2 of the cRn antibody have at least 85% (e.g., at least 90% or 95%) homology with EYAMG (SEQ ID NO:22) and SIGSSGGQTKYADSVKG (SEQ ID NO:23), respectively.

In some embodiments, the anti—FcRn antibody comprises a VH CDRl having at least 90% homology with EYAMG (SEQ ID NO:22), a VH CDR2 has at least 90% homology with SIGSSGGQTKYADSVKG (SEQ ID NO:23), and/or a VH CDR3 has at least 90% homology with LAIGDSY (SEQ ID NO:24). In one example, the cRn antibody comprises the VH CDRl region EYAMG (SEQ ID NO:22), the VH CDR2 region SIGSSGGQTKYADSVKG (SEQ ID NO:23), and/or the VH CDR3 region LAIGDSY (SEQ ID .

In other embodiments, the anti—FcRn antibody disclosed herein comprises a VH that share at least 85% (e.g., at least 90%, 95%, or 98%) sequence identity to SEQ ID NO:9. In one example, the VH of the isolated antibody comprises the amino acid sequence of SEQ ID NO:9.

In another aspect, the present disclosure provides an isolated anti—FcRn antibody comprising a heavy chain that comprises a heavy chain le region (VH) and a heavy chain constant region, wherein the VH comprises a CDR3 region having at least 85% (e. g., at least 90% or 95%) homology with LAIGDSY (SEQ ID NO:24) and the constant region has a deletion at the position corresponding to the C—terminal lysine residue of SEQ ID NO: 17. In some examples, the heavy chain variable of this cRn antibody further comprises a VH CDRl and a VH CDR2, which have at least 85% (e. g., at least 90% or 95 %) homology with EYAMG (SEQ ID NO:22), and SIGSSGGQTKYADSVKG (SEQ ID NO:23), respectively.

In other examples, the heavy chain constant region of the anti-FcRn antibody comprises the amino acid sequence of SEQ ID NO: 26.

The above-described anti-FcRn antibody can further comprise a light chain variable region (VL) that comprises a VL CDR3 at least 85% (e.g., at least 90% or 95%) identical to that of DX-2504 (CSYAGSGIYV; SEQ ID NO:25) and, optionally, a VL CDRl at least 85% (e.g., at least 90% or 95%) identical TGTGSDVGSYNLVS (SEQ ID NO: 14) and a VL CDR2 at least 85% (e.g., at least 90% or 95%) cal to GDSQRPS (SEQ ID NO: 15). In one example, the anti-FcRn dy comprises the VL CDRl region VGSYNLVS (SEQ ID NO: 14), the VL CDR2 region GDSQRPS (SEQ ID NO: 15), and/or the VL CDR3 region CSYAGSGIYV (SEQ ID NO:25), SSYAGSGIYV (SEQ ID NO: 12), or ASYAGSGIYV (SEQ ID NO: 13). In another example, the VL of the anti-FcRn antibody comprises the amino acid sequence of SEQ ID NO:8, SEQ ID NO: 10, or SEQ ID NO: 11.

In one embodiment of the present invention there is provided an isolated antibody comprising a light chain variable region (VL) and a heavy chain variable region (VH), wherein the antibody binds to human FcRn; and n the VL comprises: (i) a VL CDRl sing the amino acid sequence TGTGSDVGSYNLVS (SEQ ID NO: 14), (ii) a VL CDR2 comprising the amino acid sequence S (SEQ ID NO: 15), and (iii) a VL CDR3 comprising the amino acid sequence SSYAGSGIYV (SEQ ID NO: 12) or ASYAGSIYV (SEQ ID NO: 13), and the VH comprises: (i) a VH CDR1 comprising the amino acid ce EYAMG (SEQ ID NO: 22); (ii) a VH CDR2 comprising the amino acid sequence SIGSSGGQTKYADSVKG (SEQ ID NO: 23); and (iii) a VH CDR3 comprising the amino acid sequence LAIGDSY (SEQ ID NO: 24).

In yet another ment of the present invention there is ed a isolated antibody comprising a light chain variable region (VL), a heavy chain that comprises a heavy chain variable region (VH) and a heavy chain constant region, wherein the antibody binds to human FcRn; and wherein the VL comprises: (i) a VL CDRl comprising the amino acid sequence TGTGSDVGSYNLVS (SEQ ID NO: 14), (ii) a VL CDR2 comprising the amino acid sequence GDSQRPS (SEQ ID NO: 15), and (iii) a VL CDR3 comprising the amino acid sequence CSYAGSGIYV (SEQ ID NO: 25), SSYAGSGIYV (SEQ ID NO: 12) or ASYAGSIYV (SEQ ID NO: 13), and the VH ses: (i) a VH CDR1 comprising the amino acid sequence EYAMG (SEQ ID NO: 22); (ii) a VH CDR2 comprising the amino acid sequence comprising the amino acid sequence SIGSSGGQTKYADSVKG (SEQ ID NO: 23); and (iii) VH CDR3 comprising the amino acid sequence LAIGDSY (SEQ ID NO: 24); and the CH has a deletion corresponding to the C-terminal lysine residue at the last position of SEQ ID NO: 17.

Any of the anti-FcRn antibodies bed above can bind human FcRn with a iation constant (KD) of less than 10 nM. The cRn antibodies provided in the present disclosure can be human or humanized antibodies, or non-immunogenic in a human. For example, they can comprise a human antibody framework region.

Alternatively, the anti-FcRn antibodies can be murine antibodies. In other examples, they can be chimeric antibodies.

In some embodiments, the anti-FcRn antibodies provided herein are fulllength dies (comprising a Fc ). Alternatively, they can be antigen - binding fragments such as Fab, F(ab)'2, Fv, or ScFv. When desired, the anti-FcRn antibodies are monoclonal antibodies.

Also disclosed herein are (i) a pharmaceutical composition sing any of the antibodies described herein and a pharmaceutically able carrier, (ii) an ed nucleic acid comprising a sequence that encodes any of the antibodies provided herein, (iii) a vector comprising any of the nucleic acids comprising a sequence that s any of the antibodies provided herein, and (iv) a host cell comprising the vector comprising any of the c acids comprising a sequence that encodes any of the antibodies provided herein.

Any of the anti-FcRn antibodies described herein can be used to detect the presence of an FcRn or modulate the activity of an FcRn, either in vivo or in vitro.

In one aspect, provide herein is a method of detecting an FcRn in a sample, the method comprising: contacting the sample with any of the antibodies provided herein, detecting an ction between the antibody and the FcRn if present.

In r aspect the present disclosure provides a method of detecting an FcRn in a subject, the method comprising: administering to the subject any of the antibodies provided herein, which can be conjugated with a detectable molecule such as an imaging label (fluorescent or radioactive), and detecting an interaction n the antibody and the FcRn if present.

In yet another aspect, the present sure provides a method of modulating an FcRn activity, the method comprising: contacting an FcRn with any of the antibodies provided herein thereby modulating the activity of the FcRn.

In one aspect the invention provides a method of ng an autoimmune disorder or modulating the half life/levels of circulating IgG in a subject, the method comprising: administering to the subject any of the antibodies provided herein in an amount ive to treat the autoimmune disorder or to modulate the half life/levels of circulating IgG in the subject..

Also within the scope of the present disclosure are (a) pharmaceutical compositions for use in modulating the activity of an FcRn, modulating the half life/levels of circulating IgG, and/or ng an autoimmune disorder in a subject in need thereof, wherein the pharmaceutical compositions each comprise one of more of the anti—FcRn antibodies described herein and a pharmaceutically acceptable carrier, (b) the use of any of the anti— FcRn antibodies described herein for any of the just—noted purposes, and (c) the use of any of the anti—FcRn antibodies for the manufacture of a medicament for modulating the activity of FcRn, modulating the half life/levels of circulating IgG, and/or treating an autoimmune disorder in a subject (e.g., a human t).

These and other aspects and embodiments of the invention are described in greater detail below.

Each of the limitations of the invention can encompass various ments of the invention. It is, therefore, anticipated that each of the limitations of the invention involving any one element or combinations of ts can be included in each aspect of the invention.

This invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or rated in the gs. The invention is e of other embodiments and of being practiced or of being carried out in s ways. Also, the phraseology and terminology used herein is for the 2012/040409 purpose of ption and should not be ed as limiting. The use of “including”, “comprising”, or “having , ning , involving”, and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

BRIEF DESCRIPTION OF THE DRAWINGS The figures are illustrative only and are not required for enablement of the invention disclosed herein.

Figure I shows a Size Exclusion Chromatography (SEC) analysis of DX—2504, 532A— X53—C02 and 532A-X54-B03; Figure 2 shows an SDS—PAGE analysis of DX—2504, 532A—X53—C02 and 532A—X54— B03; Figure 3 shows the temperature ity of DX—2504, 532A—X53—C02 and 532A—X54— B03; Figure 4 shows the pH stability of DX—2504, 532A—X53—C02 and 532A—X54—B03; Figure 5 shows the stability at pH 8.3 of DX—2504, 532A—X53—C02 and 532A—X54— B03; Figure 6 shows the ity towards chemical denaturation of DX—2504, 532A—X53— C02 and 532A-X54-B03; Figure 7 shows the kinetic analysis of the interaction of hFcRn at pH6 with immobilized DX-2504, 532A-X53-C02 and 532A—X54—B03; Figure 8 shows the c analysis of the interaction at pH7.5 of hFcRn with immobilized DX-2504, 532A-X53-C02 and 532A—X54—B03; Figure 9 shows the sequences of DX2504 (SEQ ID NO:8), 532A—X53—C02 (SEQ ID NO:lO), and 532A—X54-B03 (SEQ ID NO:ll).

Figure 10 shows the anti—hFcRn H—CDR3 vs. 0 length distributions.

Figure ll shows two graphs characterizing some of the properties of selected anti— FcRn binding proteins.

Figure 12 shows the effect of anti—FcRn antibodies on the catabolism of hIgG in TG32B mice.

Figure 13 shows serum concentrations of DX—2504 and DX—2507 administered to cynomolgus monkeys.

Figure 14 shows IgG levels in cynomolgus monkeys following administration of DX— 2504 and DX—2507.

DETAILED DESCRIPTION OF THE INVENTION Disclosed herein are isolated antibodies capable of binding to human FcRn and uses thereof in detecting ce of FcRn, modulating FcRn activity, regulating the ife/level of circulating IgGs, and/or treating disorders associated with IgG abnormality, such as autoimmune disorders (e.g., multiple sclerosis, rheumatoid arthritis, lupus, immune thrombocytopenia, ankylosing spondylitis, and pemphigus), and inflammatory ers such as inflammatory bowel disease. Preferably, such anti—FcRn antibodies can (a) block the binding of non—specific human IgG/Fc portion to the c interacting site; (b) bind to both human and rat FcRn (soluble and cells); (c) bind to FcRn at pH 6; and/or (d) not exclusively bind to BZM.

In normal stances, FcRn can extend the half—life of circulating IgG. Antibodies that bind to FcRn can be used to modulate FcRn function, for example, by preventing its interaction with IgG. In particular, antibodies that block FcRn interaction with IgG can be used to reduce the half—life of IgG molecules.

In one aspect, the disclosure provides, inter alia, human antagonistic anti—human FcRn antibodies that are available for the treatment of autoimmune disorders and reduction of circulating levels of IgGs. Also sed are high affinity e Fabs (sFab) with the ability to bind through the antigen binding domain and block the ction between IgG—Fc and human FcRn or rat FcRn.

Definitions The term “binding protein” refers to a n that can interact with a target molecule.

This term is used interchangeably with “ligand.” An “FcRn—binding protein” or binding ligand” refers to a protein that can interact with an FcRn, and includes, in particular, proteins that preferentially interact with an FcRn, e.g. , IgG.

As used herein, the term “antibody” refers to a protein that includes at least one immunoglobulin variable domain or immunoglobulin variable domain sequence. For example, an antibody can include a heavy (H) chain le region (abbreviated herein as VH), and a light (L) chain le region (abbreviated herein as VL). In another example, an antibody includes two heavy (H) chain variable regions and two light (L) chain variable regions. The term “antibody” encompasses antigen—binding fragments of antibodies (e. 57., single chain antibodies, Fab and sFab fragments, F(ab')2, Fd fragments, Fv fragments, scFv, and dAb fragments) as well as complete antibodies length antibodies).

The VH and VL regions can be further subdivided into regions of hypervariability, termed “complementarity determining regions” (“CDR”), interspersed with regions that are more conserved, termed “framework regions” ("FR"). The extent of the framework region and CDR's has been precisely defined (see, Kabat, E.A., et al. (1991) Sequences ofProteins ofImmunological Interest, Fifth n, US. Department of Health and Human es, NIH Publication No. 91—3242, and Chothia, C. et al. (1987) J. Mol. Biol. 196:901—917, see also /www.hgmp.mrc.ac.uk). Kabat definitions are used . Each VH and VL is typically composed of three CDR’s and four FR’s, arranged from amino—terminus to carboxy— terminus in the following order: FRl, CDRl, FR2, CDR2, FR3, CDR3, FR4.

The term “antigen—binding fragment” of a full length antibody (or simply “antibody portion,” or “fragment”), as used , refers to one or more fragments of a full—length antibody that retain the ability to specifically bind to a target of interest. Examples of binding fragments encompassed within the term “antigen—binding fragment” of a full length antibody include (i) a Fab fragment, a monovalent fragment consisting of the VL, VH, CL and CH1 domains; (ii) a F(ab')2 fragment, a bivalent fragment ing two Fab fragments linked by a ide bridge at the hinge region; (iii) a Fd fragment consisting of the VH and CH1 domains; (iv) a Fv fragment consisting of the VL and VH domains of a single arm of an antibody, (v) a dAb fragment (Ward et al., (1989) Nature 341:544—546), which consists of a VH domain; and (vi) an isolated complementarity determining region (CDR) that retains functionality. Furthermore, although the two domains of the Fv fragment, VL and VH, are coded for by separate genes, they can be joined, using inant methods, by a synthetic linker that enables them to be made as a single protein chain in which the VL and VH s pair to form monovalent molecules known as single chain Fv (scFv). See e. 57., Bird et al. (1988) Science 3—426; and Huston et al. (1988) Proc. Natl. Acad. Sci. USA 85:5879— 5883.

Antibody fragments can be obtained using any riate technique including conventional techniques known to those with skill in the art. The term “monospecific antibody” refers to an antibody that displays a single binding specificity and affinity for a ular target, e. g., epitope. This term includes a “monoclonal antibody” or “monoclonal antibody composition,” which as used herein refer to a preparation of antibodies or fragments thereof of single molecular composition. As used herein, “isotype” refers to the antibody class (e.g., IgM or IgGl) that is encoded by heavy chain constant region genes.

As used herein, “binding affinity” refers to the apparent association constant or Ka.

The Ka is the reciprocal of the dissociation constant (Kd). A g protein may, for example, have a binding affinity of at least 105, 106, 10'7 ,10'8, 109, 10'10 and 10'11 M for a ular target molecule. Higher affinity binding of a binding ligand to a first target relative to a second target can be indicated by a higher Ka (or a smaller numerical value Kd) for binding the first target than the Ka (or numerical value Kd) for binding the second target. In such cases, the g protein has icity for the first target (e.g., a protein in a first conformation or mimic thereof) relative to the second target (e.g., the same protein in a second conformation or mimic f; or a second protein). Differences in binding affinity (e.g., for specificity or other isons) can be at least 1.5, 2, 3, 4, 5, 10, 15, 20, 50, 70, 80, 100, 500, 1000, or 105 fold.

Binding affinity can be determined by a variety of methods including equilibrium dialysis, equilibrium binding, gel filtration, ELISA, e plasmon resonance, or spectroscopy (e.g., using a fluorescence assay). Exemplary ions for evaluating binding affinity are in PBS (phosphate buffered saline) at pH 7.2 at 30°C. These techniques can be used to measure the concentration of bound and free binding protein as a function of binding protein (or target) concentration. The concentration of bound binding protein ([Bound]) is related to the concentration of free binding protein ([Free]) and the concentration of binding sites for the binding protein on the target Where (N) is the number of g sites per target molecule by the following equation: [Bound] = N - [Free]/((l/Ka) + [Free]).

It is not always necessary to make an exact determination of Ka, though, since sometimes it is sufficient to obtain a quantitative measurement of affinity, e.g., determined using a method such as ELISA or FACS analysis, is tional to Ka, and thus can be used for comparisons, such as determining r a higher affinity is, 6.57., 2—fold , to obtain a qualitative measurement of affinity, or to obtain an inference of affinity, 6.57., by activity in a functional assay, 6.57., an in vitro or in vivo assay.

The term “cognate ligand” refers to a naturally occurring ligand of an FcRn, including naturally occurring variants thereof (e.g., splice variants, naturally occurring mutants, and isoforms).

A “conservative amino acid substitution” is one in which the amino acid e is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been d in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, ic acid), uncharged polar side chains (e.g., e, asparagine, glutamine, , threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, e, phenylalanine, methionine, tryptophan), beta—branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). It is possible for many framework and CDR amino acid residues to include one or more conservative tutions.

Consensus sequences for biopolymers can include positions which can be varied among various amino acids. For example, the symbol “X” in such a context generally refers to any amino acid (e.g., any of the twenty natural amino acids or any of the nineteen non— cysteine amino acids). Other allowed amino acids can also be indicated for example, using parentheses and slashes. For example, “(A/W/F/N/Q)” means that alanine, phan, phenylalanine, asparagine, and glutamine are allowed at that particular position.

An “effectively human” globulin variable region is an immunoglobulin variable region that includes a sufficient number of human framework amino acid positions such that the immunoglobulin variable region does not elicit an immunogenic response in a normal human. An “effectively human” antibody is an antibody that includes a sufficient number of human amino acid positions such that the antibody does not elicit an immunogenic response in a normal human.

An “epitope” refers to the site on a target nd that is bound by a binding protein (e.g., an antibody such as a Fab or full length antibody). In the case where the target compound is a protein, the site can be ly composed of amino acid components, entirely composed of chemical modifications of amino acids of the n (e.g., glycosyl moieties), or composed of combinations thereof. Overlapping epitopes e at least one common amino acid residue.

Calculations of “homology” or “sequence identity” between two sequences (the terms are used interchangeably herein) are med as follows. The sequences are aligned for optimal comparison es (e.g., gaps can be introduced in one or both of a first and a second amino acid or nucleic acid sequence for optimal alignment and mologous sequences can be disregarded for comparison purposes). The optimal alignment is determined as the best score using the GAP program in the GCG software package with a Blosum 62 scoring matrix with a gap penalty of 12, a gap extend y of 4, and a frameshift gap penalty of 5. The amino acid residues or nucleotides at corresponding amino acid positions or nucleotide positions are then compared. When a position in the first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, then the molecules are identical at that position (as used herein amino acid or nucleic acid “identity” is equivalent to amino acid or c acid “homology”). The percent identity between the two sequences is a on of the number of identical positions shared by the sequences.

In one embodiment, the length of a reference sequence aligned for ison purposes is at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, 80%, 90%, 92%, 95%, 97%, 98%, or 100% of the length of the reference sequence. For example, the reference sequence may be the length of the globulin variable domain ce.

A “humanized” immunoglobulin variable region is an immunoglobulin variable region that is modified to e a sufficient number of human ork amino acid positions such that the immunoglobulin variable region does not elicit an immunogenic response in a normal human. Descriptions of “humanized” immunoglobulins include, for example, US 6,407,213 and US 5,693,762.

As used herein, the term “hybridizes under low stringency, medium stringency, high stringency, or very high stringency conditions” describes conditions for hybridization and washing. Guidance for ming hybridization reactions can be found in Current Protocols in Molecular y, John Wiley & Sons, NY. (1989), 6.31—6.36, which is incorporated by reference. Aqueous and non—aqueous methods are described in that reference and either can be used. Specific hybridization ions referred to herein are as follows: (1) low stringency hybridization conditions in 6X sodium chloride/sodium citrate (SSC) at about 45°C, followed by two washes in 0.2X SSC, 0.1% SDS at least at 50°C (the temperature of the washes can be increased to 55°C for low stringency conditions); (2) medium stringency hybridization conditions in 6X SSC at about 45°C, followed by one or more washes in 0.2X SSC, 0.1% SDS at 60°C; (3) high stringency hybridization ions in 6X SSC at about 45°C, followed by one or more washes in 0.2X SSC, 0.1% SDS at 65°C; and (4) very high stringency hybridization conditions are 0.5M sodium phosphate, 7% SDS at 65°C, followed by one or more washes at 0.2X SSC, 1% SDS at 65°C. Very high stringency conditions (4) are the preferred conditions and the ones that should be used unless otherwise specified. The disclosure includes nucleic acids that hybridize with low, medium, high, or very high stringency to a c acid described herein or to a complement thereof, e.g., c acids encoding a g protein described herein. The nucleic acids can be the same length or within 30, 20, or 10% of the length of the reference nucleic acid. The nucleic acid can correspond to a region encoding an globulin variable domain sequence.

An FcRn g protein may have mutations (e.g., at least one, two, or four, and/or less than 15, 10, 5, or 3) relative to a binding protein described herein (e.g., a conservative or non—essential amino acid substitutions), which do not have a substantial effect on the protein functions. Whether or not a particular substitution will be tolerated, i.e. will not adversely affect biological properties, such as binding activity can be ted, e. 57., using the method of Bowie, et al. (1990) Science 247:1306—1310.

An “immunoglobulin domain” refers to a domain from the variable or nt domain of immunoglobulin molecules. oglobulin domains typically contain two B— sheets formed of about seven B—strands, and a conserved disulphide bond (see, e. g., A. F. ms and A. N. Barclay 1988 Ann. Rev Immunol. 6:381—405).

As used herein, an “immunoglobulin variable domain sequence” refers to an amino acid sequence which can form the structure of an immunoglobulin variable domain such that one or more CDR regions are positioned in a conformation suitable for an n binding site. For example, the sequence may include all or part of the amino acid sequence of a naturally—occurring variable domain. For example, the sequence may omit one, two or more N— or C—terrninal amino acids, internal amino acids, may include one or more insertions or onal terminal amino acids, or may include other alterations. In one embodiment, a polypeptide that includes immunoglobulin variable domain sequence can associate with another immunoglobulin variable domain sequence to form a target binding structure (or en binding site”), e.g., a structure that preferentially interacts with an FcRn structure.

The VH or VL chain of the antibody can further include all or part of a heavy or light chain constant region, to y form a heavy or light immunoglobulin chain, respectively.

In one embodiment, the antibody is a tetramer of two heavy globulin chains and two light immunoglobulin chains, wherein the heavy and light immunoglobulin chains are inter— ted by, e.g. disulfide bonds. The heavy chain constant region includes three domains, CH1, CH2 and CH3. The light chain constant region includes a CL domain. The variable region of the heavy and light chains contains a binding domain that interacts with an antigen.

The constant regions of the antibodies typically mediate the g of the antibody to host tissues or factors, ing various cells of the immune system (e.g., effector cells) and the first component (Clq) of the classical complement system. The term “antibody” includes intact immunoglobulins of types IgA, IgG, IgE, IgD, IgM (as well as subtypes thereof). The light chains of the globulin may be of types: kappa or lambda. In one embodiment, the antibody is ylated. An antibody can be onal for antibody—dependent cytotoxicity and/or complement—mediated cytotoxicity.

One or more regions of an antibody can be human or effectively human. For e, one or more of the variable regions can be human or effectively human. For example, one or more of the CDRs can be human, e.g., HC CDRl, HC CDR2, HC CDR3, LC CDRl, LC CDR2, and LC CDR3. Each of the light chain CDRs can be human. HC CDR3 can be human. One or more of the framework regions can be human, e.g., FRl, FR2, FR3, and FR4 of the HC or LC. In one embodiment, all the framework regions are human, e.g., derived from a human somatic cell, e.g. a hematopoietic cell that es immunoglobulins or a non—hematopoietic cell. In one embodiment, the human sequences are germline sequences, e.g., encoded by a germline nucleic acid. One or more of the constant regions can be human or effectively human. In one embodiment, at least 70, 75, 80, 85, 90, 92, 95, or 98% of, or the entire of, the dy can be human or effectively human.

All or part of an antibody can be encoded by an immunoglobulin gene or a segment thereof. Exemplary human immunoglobulin genes include the kappa, lambda, alpha (IgAl and IgA2), gamma (IgGl, IgG2, IgG3, IgG4), delta, epsilon and mu constant region genes, as well as the myriad immunoglobulin variable region genes. Full—length immunoglobulin “light chains” (about 25 KDa or 214 amino acids) are encoded by a variable region gene at the NH2—terminus (about 110 amino acids) and a kappa or lambda constant region gene at the COOH——terminus. Full—length immunoglobulin “heavy chains” (about 50 KDa or 446 amino acids), are similarly encoded by a variable region gene (about 116 amino acids) and one of the other aforementioned constant region genes, e.g., gamma (encoding about 330 amino acids).

An ted composition” refers to a ition that is d from at least 90% of at least one component of a natural sample from which the isolated composition can be obtained. Compositions produced artificially or naturally can be “compositions of at least” a n degree of purity if the species or population of species of interests is at least 5, 10, 25, 50, 75, 80, 90, 92, 95, 98, or 99% pure on a weight—weight basis.

The term “mimic,” in the context of a mimic of a conformation of an FcRn or portion thereof, refers to a modified FcRn which has a bias for at least one particular conformation ve to a naturally occurring FcRn, or portion thereof.

A “non—essential” amino acid residue is a residue that can be d from the wild— type sequence of the binding agent, 6.57., the antibody, without abolishing or without ntially altering a biological activity, whereas an “essential” amino acid residue results in such a .

The phrases “parenteral administration” and “administered parenterally” as used herein means modes of administration other than enteral and topical administration, usually by injection, and includes, without limitation, intravenous, intramuscular, rterial, intrathecal, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticular, subcapsular, subarachnoid, intraspinal, epidural and intrasternal injection and infusion.

The terms “polypeptide” or “peptide” (which may be used interchangeably) refer to a polymer of three or more amino acids linked by a peptide bond, 6.57., between 3 and 30, 12 and 60, or 30 and 300, or over 300 amino acids in length. The polypeptide may include one or more unnatural amino acids. Typically, the ptide includes only natural amino acids.

A “protein” can include one or more polypeptide chains. ingly, the term “protein” asses polypeptides. A protein or polypeptide can also include one or more modifications, 6.57., a glycosylation, amidation, phosphorylation, nitrosylation, and so forth.

The term “small peptide” can be used to describe a polypeptide that is between 3 and 30 amino acids in length, e. 57., between 8 and 24 amino acids in length.

A “prophylactically effective ” refers to an amount effective, at dosages and for periods of time necessary, to achieve the desired prophylactic result. Typically, because a prophylactic dose is used in subjects prior to or at an earlier stage of disease, the prophylactically ive amount will be less than the therapeutically effective amount.

As used herein, the term “substantially identical” (or “substantially homologous”) is used herein to refer to a first amino acid or c acid sequence that contains a sufficient number of identical or equivalent (e.g., with a similar side chain, e.g., ved amino acid substitutions) amino acid residues or tides to a second amino acid or nucleic acid sequence such that the first and second amino acid or nucleic acid sequences have (or encode proteins having) similar activities, e.g., a binding activity, a g preference, or a biological activity. In the case of antibodies, the second antibody has the same specificity and has at least 50% of the affinity relative to the same antigen.

Sequences similar or homologous (e.g., at least about 85% sequence identity) to the sequences disclosed herein are also part of this application. In some embodiments, the sequence identity can be about 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or higher. In addition, substantial identity eXists when the nucleic acid segments hybridize under selective hybridization conditions (e.g., highly ent hybridization conditions), to the complement of the . The nucleic acids may be present in whole cells, in a cell lysate, or in a partially purified or substantially pure form.

Statistical significance can be determined by any art known method. Exemplary statistical tests include: the Students T—test, Mann Whitney U rametric test, and Wilcoxon non—parametric statistical test. Some statistically significant onships have a P value of less than 0.05 or 0.02. Particular binding proteins may show a difference, 6.57., in specificity or binding, that are tically icant (e.g., P value < 0.05 or 0.02). The terms “induce”, “inhibit”, “potentiate”, “elevate”, “increase”, “decrease” or the like, 6.57., which denote distinguishable qualitative or quantitative differences between two states, and may refer to a difference, 6.57., a statistically significant difference, between the two states.

A “therapeutically effective dosage” modulates a able parameter, e.g., levels of circulating IgG antibodies by a statistically significant degree or at least about 20%, by at least about 40%, by at least about 60%, or by at least about 80% relative to untreated subjects. The y of a compound to modulate a measurable parameter, e.g., autoimmunity, can be evaluated in an animal model system tive of efficacy in human autoimmune disorders. Alternatively, this property of a composition can be evaluated by 2012/040409 examining the ability of the compound to modulate a parameter in vitro, 6.57., by assays known to the skilled practitioner.

Other features and advantages of the instant invention will become more apparent from the following detailed description and claims. Embodiments of the invention can include any combination of features described . In no case does the term “embodiment” exclude one or more other features disclosed herein.

FcRn Sequences The following sequence alignment is of a human FcRn alpha chain amino acid sequence with a rat FcRn alpha chain amino acid sequence An exemplary FcRn protein can include one of these two sequences, or a fragment thereof, e.g., a fragment without the signal sequence: Signal Sequence 0L1 domain a_HUMAN: MGVPRPQPWALGLLLFLLPGSLG A78H-S.LYH.TAVSSPAPGTPAFWVSGW.GPQQY.SJ. a_RAT: MGMSQPGV-LLSLLLVLLPQTWG AdPR-P.MYH.AAVSDLSTGLPSFWATGW.GAQQY.TJ. 0L1 domain 0L2 domain a_HUMAN: YNS.RGfiAfiPCGAWVWENQVSWYWfiKfiiiD.RIKfiK.b.fiAbKA.GGK——GP YT-QG..G a_RAT: YNN.RQHADPCGAWIWENQVSWYWfiKfiiiD.KSKfiQ.b.fiAIRi.fiNQINGi*J bi-QG..G 0L2 domain a_HUMAN: Cm.GPDNLSVPLAKbA.NGfifibMNbDLKQGLWGGDWPEALAISQRWQQQD<AANK?LTF. a_RAT: C'.APDNSSLPLAVbA.NGfifibMRbNPRiGNWSGfiWPfiiDIVGNLWMKQPfiAARKfiSfit._*J 0L2 domain 0L3 domain a_HUMAN: JFSCPiR.RfiH.fiRGRGN.fiWK fiPPSMR.KARPSSPGFSVJTCSAFSFYPP?.QLRF-RN a_RAT: R.LGH.?RGRQN.fiWK .KARPGNSGSSVJTCAAFSFYPP?.KFRF.RN 0L3 domain a_HUMAN: GJAAGTGQGDFGPNSDGSFHASSSJTVKSGDEHHYCCIVQHAG.AQP.RVfi.fi a_RAT: GNCSTGPNGDGSFHAWSL.fiVKRGDfiHHYQCQVfiHfiG.AQP.TVD.D Transmembrane Cytop asm c domain G_HUMAN: VLVVGIVIGV..LTAAAVGGA..W RRMRSGAPAPWISJRGDDTGV..PTPGWAQJ. a_RAT: SPARSSVPVVGIILGL.-VVVAIAGGV..W NRMRSG-PAPWLS-SGDDSGD..PGGN.PP a_HUMAN: VNVIPAIA (SEQ ID NO:1) a_RAI: fiAfiPQGVNAFPAIS (SEQ ID NO:2) The following sequence alignment is of a human [32 microglobulin amino acid ce with a rat B2 microglobulin amino acid sequence. An exemplary FcRn protein can e one of these two sequences, or a fragment thereof, 6.57., a fragment Without the signal sequence: Signal Sequence B2 microglobulin BZm_human: MSRSVALAVLALLSLSGLEA IQRIPKIQVYSRHPAENGKSNFANCYVSGFHPSDIDVD..J.

B2m_rat : MARSVTVIFLVLVSLAVVLA IQKIPQIQVYSRHPPENGKPNFJNCYVSQbHPPQIfiIfi..

BZ microglobulin BZm_human: KNGfiRIfiKVfiHSD-SbSKDWSbYL.YYifibIPIfiKDfiYACRVNHVIJSQPKIVKWDRDM (S ID NO:3) B2m_rat : KNG<KIPNIfiMSD-SbSKDWSbYI.AHIfibIPIfiIDVYACRVKHVI.KVPKIVIWDRDM (S ID NO:4) An exemplary c acid sequence encoding an FcRn protein alpha chain can include the following sequences: FcRn alpha nucleotide sequence (Homo sapiens): GITCIICAGGIACGAGGAGGGCAIIGIIGICAGICIGGACCGAGCCCGCAGAGCCCCICCICGGCGICCI GGCCGIGCCCGCGGIGICCCGGGAGGAAGGGGCGGGCCGGGGGICGGGAGGAGICACGIGCCCC CICCCGCCCCAGGICGICCiCiCAGCAIGGGGGiCCCGCGGCCICAGCCCIGGGCGCIGGGGCICCIGCI CIITCICCIICCIGGGAGCCIGGGCGCAGAAAGCCACCTCICCCICCIGIACCACCIIACCGCGGIGICC ICGCCIGCCCCGGGGACICCIGCCIICIGGGIGICCGGCIGGCIGGGCCCGCAGCAGIACCIGAGCIACA AIAGCCIGCGGGGCGAGGCGGAGCCCIGIGGAGCIIGGGICIGGGAAAACCAGGIGICCIGGIAIIGGGA GAAAGAGACCACAGAICIGAGGAICAAGGAGAAGCTCIITCIGGAAGCIIICAAAGCIIIGGGGGGAAAA GGICCCIACACTCIGCAGGGCCIGCIGGGCIGIGAACIGGGCCCIGACAACACCICGGIGCCCACCGCCA AGIICGCCCIGAACGGCGAGGAGIICAIGAAIIICGACCICAAGCAGGGCACCIGGGGIGGGGACIGGCC CGAGGCCCIGGCTATCAGICAGCGGIGGCAGCAGCAGGACAAGGCGGCCAACAAGGAGCICACCIICCIG CTATTCICCIGCCCGCACCGCCIGCGGGAGCACCIGGAGAGGGGCCGCGGAAACCIGGAGIGGAAGGAGC CCCCCICCAIGCGCCIGAAGGCCCGACCCAGCAGCCCIGGCIIIICCGIGCIIACCIGCAGCGCCIICIC CITCIACCCICCGGAGCIGCAACIICGGIICCIGCGGAAIGGGCIGGCCGCIGGCACCGGCCAGGGIGAC IICGGCCCCAACAGIGACGGAICCIICCACGCCICGICGICACIAACAGICAAAAGIGGCGAIGAGCACC ACIACIGCIGCAIIGIGCAGCACGCGGGGCIGGCGCAGCCCCICAGGGIGGAGCIGGAAICICCAGCCAA GICCiCCGiGCiCGiGGiGGGAAiCGiCAiCGGIGICiiGCiACiCACGGCAGCGGCIGIAGGAGGAGCI CIGIIGIGGAGAAGGAIGAGGAGIGGGCIGCCAGCCCCIIGGAICICCCIICGIGGAGACGACACCGGGG IGCCCACCCCAGGGGAGGCCCAGGAIGCIGAIIIGAAGGAIGIAAAIGIGAIICCAGCCACCGC CIGACCAICCGCCAIICCGACIGCIAAAAGCGAAIGIAGICAGGCCCCIIICAIGCIGIGAGACCICCIG GAACACIGGCAICICIGAGCCICCAGAAGGGGiiCiGGGCCiAGiiGiCCiCCCiCiGGAGCCCCGICCI 40 GIGGICIGCCICAGIiiCCCCiCCiAAIACAIAIGGCIGIIIICCACCICGAIAAIAIAACACGAGIIIG GGCCCGAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA (S?Q ID NO:5) WO 67039 The nucleic acid e of an exemplary human FcRn —cellular domain) plus GPI DNA sequences (lowercase bold) is set forth below.

ATGGGGGTCCCGCGGCCTCAGCCCTGGGCGCJGGGGCJCCJGCJCJJJCJCCJJCCJGGGAGCCTGGGCG CAGAAAGCCACCTCTCCCTCCTGTACCACCTTACCGCGGTGTCCTCGCCTGCCCCGGGGACTCCTGCCTT CTGGGTGTCCGGCTGGCTGGGCCCGCAGCAGTACCTGAGCTACAATAGCCTGCGGGGCGAGGCGGAGCCC TGTGGAGCTTGGGTCTGGGAAAACCAGGTGTCCTGGTATTGGGAGAAAGAGACCACAGATCTGAGGATCAA GGAGAAGCTCTTTCTGGAAGCTTTCAAAGCTTTGGGGGGAAAAGGTCCCTACACTCTGCAGGGCCTGCTGG GCTGTGAACTGGGCCCTGACAACACCTCGGTGCCCACCGCCAAGTTCGCCCTGAACGGCGAGGAGTTCATG AATTTCGACCTCAAGCAGGGCACCTGGGGTGGGGACTGGCCCGAGGCCCTGGCTATCAGTCAGCGGTGGCA GCAGCAGGACAAGGCGGCCAACAAGGAGCJCACCJJCCJGCJAJJCJCCJGCCCGCACCGCCTGCGGGAGC ACCTGGAGAGGGGCCGCGGAAACCTGGAGTGGAAGGAGCCCCCCTCCATGCGCCTGAAGGCCCGACCCAGC AGCCCTGGCTTTTCCGTGCTTACCTGCAGCGCCTTCTCCTTCTACCCTCCGGAGCTGCAACTTCGGTTCCT GCGGAATGGGCTGGCCGCTGGCACCGGCCAGGGTGACTTCGGCCCCAACAGTGACGGATCCTTCCACGCCT CGTCGTCACTAACAGTCAAAAGTGGCGATGAGCACCACTACTGCTGCATTGTGCAGCACGCGGGGCTGGCG CAGCCCCTCAGGGTGGAGCTGGAATCTCCAGCCAAGTCCTCCcggccgctcgacgggctacgagcatcagt actaggcgcaggcctactactatcactactaccagcactactacgatttgggccataa (SEQ ID NO:6) An exemplary nucleic acid sequence encoding a Beta—2—microglobulin (BZM) can include the following sequences: Beta—2—microglobulin (BZM) nucleotide (Homo sapiens): AGTGGAGGCGTCGCGCTGGCGGGCATTCCTGAAGCTGACAGCATTCGGGCCGAGATGTCTCGCT CCGJGGCCJJAGCJGJGCJCGCGCJACJCJCJCJiJCJGGCCiGGAGGCTATCCAGCGTACTCCAAAGAT TCAGGTTTACTCACGTCATCCAGCAGAGAATGGAAAGJCAAAJJJCCJGAAJJGCJAJGJGJCJGGGJii CATCCATCCGACATTGAAGTTGACTTACTGAAGAATGGAGAGAGAATTGAAAAAGTGGAGCATTCAGACT TGTCTTTCAGCAAGGACJGGJCJJJCJAJCJCJJGJACJACACJGAAJJCACCCCCACTGAAAAAGATGA GTATGCCTGCCGTGTGAACCATGTGACTTTGTCACAGCCCAAGATAGTTAAGTGGGATCGAGACATGTAA GCAGCATCATGGAGGTTTGAAGATGCCGCAJJJGGAJJGGAJGAAJJCCAAAJJCJGCJJGCJJGCJJJJ . JGAJAJGCJ. JAJACACJ. JACACJ. J. JAJGCACAAAAJGJAGGGJ. JAJAAJAAJGJ. JAACAJGGAC AJGAJCJ. J.CJ. J. JAJAAJ. JCJACJ. J. JGAGJGCJGJCJCCAJGJ J. JGAJGJAJCJGAGCAGGTTGCTCCACA GGTAGCTCTAGGAGGGCTGGCAACTTAGAGGTGGGGAGCAGAGAATTCTCTTATCCAACATCAACATCTT GGJCAGAJiJGAACJCJJCAAJCJCJJGCACJCAAAGCJJGJJAAGAJAGJJAAGCGJGCAJAAGJJAAC JJCCAAJJJACAJACJCJGCJJAGAAJJJGGGGGAAAATTTAGAAATATAATTGACAGGATTATTGGAAA TTTGTTATAATGAATGAAACAJiiJGJCAJAJAAGAJJCAJAJJJACJJCJJAJACAJJJGAJAAAGJAA GGCAJGGJ. JGJGGJ. JAAJCJGGJ. J. JAJ. J. J. J. JGJ. JCCACAAGJ. JAAAJAAAJCAJAAAACJ. JGAJGJGJ. JA TCTCTTA (SEQ ID NO:7) FcRn binding dies 40 DX2504 is an FcRn binding antibody that is described in W02009/131702 and US— 2009—0324614—Al. Both W02009/131702 and US—2009—03246l4—Al are orated by reference into this application in their entirety. DX2504 was generated by a combination of monoclonal antibody technology and phage display experiments using FcRn polypeptides or cells expressing FcRn as the target. In addition, the sequence of DX2504 was ned to 45 lower immunogenicity. The sequences of DX2504 light chain and heavy chain are shown below: Light chain Variable Region (SEQ ID NO:8): FRl—L CDRl—L FR2—L CDR2—L QSALTQPASVSGSPGQSITISC TGTGSDVGSYNLVS WYQQHPGKAPKLMIY GDSQRPS FR3—L CDR3—L FR4—L GVSNRFSGSKSGNTASLTISGLQAfiDfiADYYC CSYAGSGIYV VTVL Light Chain Full Length (SEQ ID NO: 16; CL underlined): QSALTQPASVSGSPGQSITISCTGTGSDVGSYNJVSWYQQHPGKAPKLMIYGDSQRPSGVSNRFSGSKSGNTASL TISGLQAfiDfiADYYCCSYAGSGIYVFGTGTKVTVLGQPKANPIViLbPPSSfinLQAVKATLVCJISDFYPGAVTV AWKADGSPV{AGVETTKPSKQSNNKYAASSYLS.TPVQWKSHRSYSCQVIHfiGSIVfiKiVAPILCS Heavy chain Variable Region (SEQ ID NO:9): FRl—H CDRl—H FRZ—H CDR2—H fiVQLLflSGGGLVQPGGSLRDSCAASGFTFS EYAMG WVRQAPGKGLEWVS SIGSSGGQTKYADSVKG FR3—H CDR3—H FR4—H RFTISRDNSKNTLYLQMNS.RAVDTAVYYCAR LAIGDSY WGQGTMVTVSS Heavy Chain Full :Length (SEQ ID NO: 17; CH underlined) fiVQ.LfiSGGG.VQPGGSLRLSCAASGFTFSEYAMGWVRQAPG{GLEWVSSIGSSGGQTKYADSV<GRFTISRDNS <NT-Y-Q DTAVYYCARLAIGDSYWGQGTMVTVSSASTKGPSVFPLAPSS{STSGGTAALGCLVKDYFP EPVTVSWWSGAATSGV{TFPAVLQSSGLYSJSSVVTVPSSSLGTQTYICNVNH{PSWTKVDKRVEP{SCDKTHTC PPCPAP?.LGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHfiDPfiVKbNWYVDGVLVHNAKIKPRfifiQYNSIYR VVSVLTV.HQDWLWGKVYKCKVSNKALPAPIEKTISKAKGQPRfiPQVYILPPSRun iKNQVSLTCAVKGFYPSD IAVfiWfiSWGQPfiNWYKIIPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHVA.{NHYTQKS.S-SPGK In addition to binding FcRn, DX2504, or precursor antibodies, has been shown to block the binding of IgG—Fc to FcRn expressing cells (Example 21 of /131702).

Furthermore, administering DX2504 to Tg32B mice, a mouse in which the mouse FcRn is replaced by the human FcRn, lowered the levels of a human IgG which was administered to the mice previously (Example 27 of /131702). Moreover, the administration of DX2504 in cynomolgus monkeys resulted in the lowering of IgG serum levels (Example 27 of WO2009/l3 1702).

It was unexpectedly found herein that altering either the CDR3 of the light chain (e.g., the cysteine mutants bed herein) or the constant region of the heavy chain (e.g., the deletion s described herein) of DX2504 resulted in FcRn g antibodies with improved properties when compared to DX2504. This finding was unexpected at least in part because, generally, an antibody that has gone through as many rounds of sequence optimization, such as DX2504, cannot be easily zed further by introducing additional mutations.

Cysteine Mutants The cysteine mutants of DX2504 described herein lack a cysteine e at the first position of at least one CDR3, for example, the first on of the VL CDR3 of DX2504 being replaced with another amino acid residue such as Ala, Ser, or a conservative tution thereof. Exemplary cysteine mutants include, but are not limited to, 532A—X53— C02 (having a VL set forth as SEQ ID NO: 10) and 532A—X53—B03 (having a VL set forth as SEQ ID NO: 1 1). Such mutants preserve the FcRn—binding activity, e.g., binding to human FcRn with a dissociation constant (KD) of less than 10 nM, which can be determined by a e method. In some examples, the cysteine mutant contains two VL chains, either one or both of which do not have a cysteine at the first position of the VL CDR3 region.

The cysteine mutant described herein can comprise a VL chain, in which the CDRl, CDR2, and CDR3 share at least 70% (e.g., at least 75%, 80%, 85%, 90%, or 95%) sequence identity to the VL CDRl and VL CDR2 of DX2504 (SEQ ID NOs: l4 and 15, tively; identical to those in 532A—X53—C02 or 532A—X53—B03) and an altered VL CDR3 of DX2504 (SEQ ID NO:l2 or 13, the VL CDR3 of 532A—X53—C02 or 532A—X53—B03). In some embodiments, one or more of the VL CDRs share at least 70% sequence identity to that of the corresponding CDR(s) of 532A—X53—C02 or 532A—X53—B03. For example, the cysteine mutant has at least 70% homology (at least 75%, 80%, 85%, 90%, or 95%) in the VL CDR3 region with the sequences SSYAGSGIYV (SEQ ID NO: 12), or ASYAGSGIYV (SEQ ID NO: 13).

In other embodiments, the VL CDRs of the cysteine mutant, in combination, share at least 70% sequence identity to those of 532A—X53—C02 or 532A—X53—B03, in ation.

For example, an antibody with at least 90% homology in the CDRl, CDR2 and CDR3 region with the reference CDR sequences refers to an antibody that has at least 9 out of every 10 amino acids in the combined CDRl, CDR2 and CDR3 regions identical to the amino acids found in the combined CDRl, CDR2 and CDR3 regions of 532A—X53—C02.

Alternatively, the antibody can have up to 1, up to 2, up to 3, up to 4, or up to 5 amino acid tutions in the VL CDR3 region as compared to the sequences SSYAGSGIYV (SEQ ID NO: 12) or ASYAGSGIYV (SEQ ID NO: 13). In some embodiments, the cysteine mutant can n up to 3 substitutions in the VL CDR3 region as compared to the CDR3 region of 2012/040409 DX2504. The one or more of the amino acids substitutions can be vative amino acid substitutions.

Moreover, the cysteine mutant antibodies can have up to 1, up to 2, up to 3, up to 4, up to 5, up to 6, up to 7, up to 8, up to 9, up to 10, or up to 15 amino acid substitutions in the CDR1, CDR2 and CDR3 region as compared to the sequences of the CDR1, CDR2 and CDR3 regions of 532A—X53—C02 or 532A—X53—B03. In some embodiments, they can n up to 10 substitutions in the VL CDR1, CDR2, and CDR3 regions collectively. In one example, the one or more of the amino acids substitutions are conservative amino acid substitutions.

In some embodiments, the cysteine mutant comprises a VL chain that share at least 70% (e.g., at least 75%, 80%, 85%, 90%, 95%, 97%, or 98%) sequence identity to the VL sequence of 532A—X53—C02 (SEQ ID NO:lO) or that of 532A—X53—B03 (SEQ ID NO:ll). In one example, the cysteine mutant comprises the same VL CDR3 region as 532A—X53—C02 or 53—B03, and optionally, the same VL CDRl and CDR2 s as the two exemplary mutants.

The “percent identity” of two amino acid sequences can be determined using the algorithm of Karlin and Altschul Proc. Natl. Acad. Sci. USA 87:2264—68, l990, modified as in Karlin and Altschul Proc. Natl. Acad. Sci. USA 90:5873—77, 1993. Such an algorithm is incorporated into the NBLAST and XBLAST programs (version 2.0) of Altschul, et al. J.

Mol. Biol. 215:403—10, l990. BLAST protein searches can be performed with the XBLAST program, score=50, wordlength=3 to obtain amino acid sequences homologous to the protein molecules of interest. Where gaps exist n two sequences, Gapped BLAST can be utilized as described in ul et al., Nucleic Acids Res. 25(17):3389—3402, 1997. When utilizing BLAST and Gapped BLAST programs, the default ters of the respective programs (e.g., XBLAST and NBLAST) can be used.

In some embodiments, the cysteine mutants described herein can contain one or more mutations (e.g., conservative amino acid substitutions) within the framework regions (FRs) as compared to the two exemplary mutants described above and in Example 1 below. As known in the art, mutations within the FR regions are unlikely to affect the antigen—binding activity of the dy. In other embodiments, the cysteine s described herein can contain one or more mutations (e.g., l, 2, or 3 ons such as conservative amino acid substitutions) within one or more of the CDR regions as compared to 532A—X53—C02 or that of 532A—X53— B03. Preferably, such mutants retain the same regions/residues responsible for antigen— binding as the parent, such as the same icity—determining es inside the CDRs.

In general, a cysteine residue provides a protein with unique properties because a ne residue can form a covalent bond with other cysteines. Mutating a cysteine often s in proteins with significantly altered ties. It was therefore unexpected that the antibodies with the cysteine in CDR3 of light chain mutated to either a serine (C54—C02) or an alanine (X54—B03) were found to be more homogeneous than DX—2504, as measured by size exclusion chromatography (Figure l) and by SDS—PAGE analysis (Figure 2). It was also unexpected that cysteine mutants would be more stable, with respect to the percent monomeric IgG species, over a 30 day incubation at 37°C tion (Figure 3) or following a 15 day incubation at pH 8.3 (Figure 4). Mutations in the CDRs of an antibody often diminish the affinity of antigen binding. It was therefore further unexpected that mutating a cysteine in the CDR3 of the light chain of DX—2504 did not affect the affinity of antigen binding (Figures 7 and 8).

Any of the cysteine s described above can further comprise a heavy chain variable region (VH), which comprises VH CDRl, VH CDR2, and VH CDR3 regions. The VH can be the same as that of DX2504 (SEQ ID NO:9) or a functional variant f. In some embodiments, the VH CDRs in the functional variant share at least 70% (e. g., at least 75%, 80%, 85%, 90%, or 95%) sequence identity to those of DX2504 (SEQ ID NOs: 22, 23, and 24). In one example, one or more of the VH CDRs share at least 70% sequence ty to that of the corresponding VH CDR(s) of DX2504, for example, having at least 70% homology (at least 75%, 80%, 85%, 90%, or 95%) in the VH CDR3 region with the sequences LAIGDSY (SEQ ID NO:24).

In another example, the VH CDRs of the functional variant, in combination, share at least 70% sequence ty to those of , in ation. For example, an antibody with at least 90% gy in the CDRl, CDR2 and CDR3 region with the reference CDR sequences refers to an antibody that has at least 9 out of every 10 amino acids in the combined CDRl, CDR2 and CDR3 regions identical to the amino acids found in the combined CDRl, CDR2 and CDR3 regions of DX2504.

Alternatively, the functional mutant can contain up to 1, up to 2, up to 3, up to 4, or up to 5 amino acid substitutions in the CDR3 region as compared to the CDR3 sequences of DX2504 (LAIGDSY; SEQ ID NO:24). In some embodiments, the functional variants include up to 3 substitutions in the VH CDR3 region as compared to the CDR3 region of DX2504. In one example, the one or more of the amino acids substitutions are conservative amino acid substitutions. er, the functional variant can contain up to 1, up to 2, up to 3, up to 4, up to 5, up to 6, up to 7, up to 8, up to 9, up to 10, up to 11, up to 12, up to 13, up to 14, or up to 15 amino acid substitutions in the CDR1, CDR2 and CDR3 region as compared to the sequences of the CDR1, CDR2 and CDR3 regions of DX2504. In some embodiments, they contain up to 10 substitutions in the VH CDR1, CDR2, and CDR3 regions collectively. In one example, the one or more of the amino acids substitutions are conservative amino acid substitutions.

In some embodiments, the functional variant comprises a VH chain that share at least 70% (e.g., at least 75%, 80%, 85%, 90%, 95%, 97%, or 98%) sequence identity to the VH sequence of DX2504 (SEQ ID NO:9). In one e, the functional variant comprises the same VH CDR3 region as DX2504, and ally, the same VH CDRl and CDR2 regions as DX2504.

When desired, the functional variant of DX2504 heavy chain as described herein can contain one or more mutations (e.g., conservative amino acid substitutions) Within the framework regions (FRs) of DX2504 (see above description). As known in the art, ons Within the FR regions are unlikely to affect the antigen—binding ty of the antibody. In other embodiments, the cysteine s described herein can contain one or more mutations (e. g., l, 2, or 3 mutations such as conservative amino acid tutions) Within one or more of the CDR regions as compared to DX2504. Preferably, such variants retain the same regions/residues responsible for antigen—binding as the parent, such as the same specificity— determining residues inside the CDRs.

In one example, the cysteine mutant of DX2504 described herein comprises a light chain at least 70% (e.g., at least 75%, 80%, 85%, 90%, or 95%) homology With 532A—X53— C02 or 532A—X53—B03, and a heavy chain comprising the same CDRs as that of DX2504 (e. g., the same heavy chain variable region as that of DX2504). In r example, the mutant comprises the same VL as 532A—X53—C02 or 532A—X53—B03, and the same VH as DX2504.

Deletion Mutants It has also been discovered, unexpectedly, that the deletion of the inal lysine residue of the heavy chain of DX2504 resulted in an cRn antibody (DX2507) having increased antibody retention and a higher reduction of IgG in an animal model as compared to DX2504 (Figures 13 and 14).

Accordingly, also described herein are deletion mutants that lack the inal lysine e in its heavy chain as compared to the heavy chain of . More specifically, the heavy chain of the deletion mutant described herein can be otherwise identical to the heavy chain of DX2504 (SEQ ID NO: 17) or to the heavy chain of any of the functional ts of DX2504 as described above except for the deletion of the amino acid residue corresponding to the C—terminal lysine residue in the heavy chain of DX2504 (SEQ ID NO: 17). One example of such a heavy chain is that of DX2507 (SEQ ID NO: 19) described in e 2 below.

The deletion mutants described above can further comprise a light chain, which can comprise the VL region of DX2504 or the VL region of any of the cysteine mutants bed herein.

In some examples, the deletion mutant comprises a light chain comprising the same VL CDRs as DX2504, 532A—X53—C02, or 532A—X53—B03 (e.g., the same VL as DX2504, 532A—X53—C02, or 532A—X53—B03), a heavy chain comprising the same VH CDRs as DX2504 (e.g., the same VH as DX2504) and a heavy chain constant region having a deletion at the position corresponding to the C—terminal lysine residue of the heavy chain of DX2504.

Any of the cysteine and deletion mutants described herein can bind to human FcRn with a dissociation constant (KD) of less than 10 nM.

In addition to having the amino acids sequences described herein, the anti—FcRn antibodies described herein may have any structural framework. Thus, for instance the CDRl, CDR2, ad CDR3 regions described above, may be embedded in a “traditional” antibody framework, or may embedded in a scFv or Fab framework. The anti—FcRn antibody described herein can be a full—length antibody or an antigen—binding fragment thereof, e.g., Fab, F(ab)’2, Fv or ScFv antibody. It can be a non—human antibody such as a murine antibody (e.g., a onal antibody produced by a hybridoma cell line), a chimeric dy, or a humanized antibody.

Also within the scope of the present disclosure are nucleic acids comprising nucleotide sequences encoding the VH and/or VL of any of the anti—FcRn dies described herein (e.g., any of the cysteine mutants or any of the deletion mutants described above).

Such c acid sequences can be inserted into expression vectors, which can be introduced into suitable host cells (e.g., bacterial cells such as E. coli cells, yeast cells, insect cells, plant cells, or mammalian cells) for production of the anti—FcRn antibodies via recombinant technology.

Methods of Making Mouse Monoclonal Antibodies Methods of making monoclonal antibodies have been described (Harlow et al., Antibodies A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (1988)). In some instances, as a first step, a rodent, 6.57., a mouse is zed with an antigenic polypeptide to generate an antibody response. Because FcRn is expressed ubiquitously and exhibits high degree of homology between species, polypeptide zation has not been successful in ing high affinity FcRn ic monoclonal antibodies or FcRn monoclonal blocking antibodies. To solve this problem DNA vaccination can be performed (Castagliola et al., J. Immunology 160:1458 ). DNA vaccination involves zing a rodent, e.g., a mouse with a cDNA construct encoding FcRn or a fragment thereof. zation can be stered intramuscularly, intraperitoneally, subcutaneously, intravenously, ermally or directly into the lymph node. In one embodiment the immunizations stered intramuscularly. DNA vaccination can be administered with an adjuvant, e.g. Freunds complete adjuvant or Freund’s incomplete nt. The DNA vaccination can be accompanied by administration of a cardiotoxin to increase the antibody titer. Administration of a cardiotoxin causes cell death and cell regeneration which enhances cellular uptake of the administered DNA vaccine. The toxin can also increase inflammation which results in a more robust immune response.

Antibody secreting cells (B cells) are isolated from the rodent. Typically the B cell can be isolated from the rodents spleen and fused with a myeloma cell line. The myeloma cell lines are immortalized cell lines that do not produce antibodies. The a cell line can be chosen from, but is not limited to P3—X63Ag8, X63Ag8.653, Sp2/0—Agl4, FO, NSI/l- Ag4-l, NSO/l, FOX-NY, Y3-Agl.2.3, YB2/0 and IR983F.

Splenocytes are fused with the myeloma cell line to form a hybridoma. Fusion can be mediated by mixing the two cell types with polyethylene glycol for an appropriate period of time (e.g. five minutes). The formed hybridomas are grown in cell culture using an appropriate selection media (e.g. HAT) and screened for their ability to produce a monoclonal dy against FcRn. Screening can be performed using known immunological techniques, 6.57. an ELISA. r approach to making FcRn specific monoclonal antibodies is to immunize a transgenic FcRn knockout mouse with soluble human FcRn, see, PCT Application WO 02/43658. WO 02/43658 describes a transgenic mouse whose genome comprises a homozygous disruption in its endogenous FcRn gene, wherein said homozygous disruption prevents expression of a functional FcRn protein. The monoclonal dy of the ion is not made in a transgenic mouse whose genome comprises a homozygous disruption in its endogenous FcRn gene, wherein said homozygous disruption prevents expression of a functional FcRn protein. The monoclonal antibody of the ion is not comprised of a B cell from a transgenic mouse whose genome comprises a homozygous tion in its endogenous FcRn gene, wherein said homozygous disruption prevents expression of a onal FcRn protein.

Humanized Anti—FcRn Antibodies Display Libraries A display library can be used to identify antibodies that bind to the FcRn. A display library is a collection of entities; each entity includes an accessible polypeptide component and a recoverable ent that encodes or fies the polypeptide component. The polypeptide component is varied so that different amino acid sequences are represented. The polypeptide component can be of any length, 6.57. from three amino acids to over 300 amino acids. In a selection, the polypeptide component of each member of the library is probed with the FcRn and if the polypeptide component binds to the FcRn, the display library member is identified, lly by retention on a support. In addition, a display library entity can include more than one polypeptide component, for example, the two polypeptide chains of an sFab.

Retained display library members are recovered from the t and analyzed. The analysis can include amplification and a subsequent selection under similar or dissimilar conditions. For example, positive and negative selections can be ated. The analysis can also include determining the amino acid sequence of the polypeptide component and cation of the polypeptide component for detailed characterization.

A variety of formats can be used for display libraries. Examples include the following.

WO 67039 Phage Display. One format utilizes viruses, particularly iophages. This format is termed “phage display.” The protein component is typically covalently linked to a bacteriophage coat protein. The linkage results from translation of a nucleic acid encoding the protein component fused to the coat protein. The linkage can e a flexible e linker, a protease site, or an amino acid incorporated as a result of suppression of a stop codon. Phage display is described, for example, in US. 5,223,409; Smith (1985) Science 228:1315-1317; WO 92/18619; WO 91/17271; WO 92/20791; WO 92/15679; WO 88; WO 92/01047; WO 92/09690; WO 90/02809; de Haard et al. (1999) J. Biol. Chem 274:18218—30; Hoogenboom et al. (1998) Immunotechnology 4:1—20; Hoogenboom et al. (2000) Immunol Today 2:371—8; Fuchs et al. (1991) Bio/Technology 9:1370—1372; Hay et al. (1992) Hum Antibod Hybridomas 3:81—85; Huse et al. (1989) Science 246:1275—1281; Griffiths et al. (1993) EMBO J 12:725—734; Hawkins et al. (1992) JMol Biol 9—896; Clackson et al. (1991) Nature 352:624—628; Gram et al. (1992) PNAS 6—3580; Garrard et al. (1991) Bio/Technology 9: 1373— 1377; and boom et al. (1991) Nuc Acid Res 19:4133—4137.

Phage display systems have been developed for filamentous phage (phage f1, fd, and M13) as well as other bacteriophage. The filamentous phage display systems typically use fusions to a minor coat protein, such as gene III protein, and gene VIII protein, a major coat n, but fusions to other coat proteins such as gene VI protein, gene VII protein, gene IX protein, or domains thereof can also been used (see, e. 57., WO 00/71694). In one embodiment, the fusion is to a domain of the gene III protein, e. g., the anchor domain or “stump,” (see, e.g., US. Patent No. 5,658,727 for a description of the gene III protein anchor domain). It is also possible to physically associate the protein being displayed to the coat using a ptide linkage.

Bacteriophage displaying the n component can be grown and harvested using standard phage preparatory methods, e. 57., PEG precipitation from growth media. After selection of individual display , the nucleic acid encoding the selected protein components can be isolated from cells infected with the selected phages or from the phage themselves, after amplification. dual colonies or plaques can be picked, the nucleic acid ed and sequenced.

Other Display Formats. Other display formats include cell based display (see, e.g., WO 03/029456), protein—nucleic acid fusions (see, e. 57., US 6,207,446), and ribosome display (See, e.g., Mattheakis et al. (1994) Proc. Natl. Acad. Sci. USA 91:9022 and Hanes et al. (2000) Nat Biotechnol. 7—92; Hanes et al. (2000) Methods Enzymol. 328:404—30; and Schaffitzel et al. (1999) J Immunol Methods. 2): 1 19-35).

Scaffolds. lds for display can include: antibodies (e.g., Fab fragments, single chain Fv molecules (scFV), single domain antibodies, camelid antibodies, and camelized antibodies); T—cell receptors; MHC proteins; extracellular domains (e.g., fibronectin Type III repeats, EGF repeats); protease inhibitors (e.g., Kunitz domains, ecotin, BPTI, and so forth); TPR repeats; trifoil structures; zinc finger s; DNA—binding proteins; particularly monomeric DNA binding ns; RNA binding proteins; s, e.g., proteases (particularly inactivated proteases), RNase; chaperones, e.g., thioredoxin and heat shock proteins; intracellular ing domains (such as SH2 and SH3 domains); linear and constrained es; and linear peptide substrates. Display libraries can include synthetic and/or natural diversity. See, e.g., US 2004—0005709.

Display technology can also be used to obtain antibodies that bind particular epitopes of a . This can be done, for example, by using competing non—target molecules that lack the particular epitope or are mutated within the epitope, e.g. with alanine. Such non— target molecules can be used in a negative selection procedure as described below, as competing molecules when binding a display library to the , or as a pre—elution agent, e.g., to capture in a wash solution dissociating display library members that are not specific to the target.

Iterative Selection. In one embodiment, display library technology is used in an iterative mode. A first display library is used to identify one or more antibodies that bind a target. These identified antibodies are then varied using a mutagenesis method to form a second display library. Higher affinity antibodies are then selected from the second library, e.g. , by using higher stringency or more competitive binding and g ions.

In some entations, the mutagenesis is targeted to regions known or likely to be at the binding interface. In the case of antibodies, the mutagenesis can be directed to the CDR regions of the heavy or light chains as described . Further, mutagenesis can be directed to framework regions near or adjacent to the CDRs. In the case of antibodies, mutagenesis can also be limited to one or a few of the CDRs, e.g., to make precise step—wise improvements. ary nesis techniques include: error—prone PCR, recombination, DNA shuffling, site—directed mutagenesis and cassette mutagenesis.

In one example of iterative selection, the methods described herein are used to first identify an antibody from a display library that binds an FcRn with at least a l binding specificity for a target or a l activity, e.g., an equilibrium dissociation nt for binding of less than 1 nM, 10 nM, or 100 nM. The nucleic acid ce encoding the initial identified antibodies are used as a template nucleic acid for the introduction of variations, 6.57., to fy a second antibody that has enhanced properties (e.g., binding affinity, kinetics, or stability) relative to the initial antibody.

Off-Rate Selection. Since a slow dissociation rate can be predictive of high affinity, particularly with respect to ctions between antibodies and their targets, the s described herein can be used to isolate antibodies with a desired kinetic iation rate (e.g., reduced) for a binding interaction to a target.

To select for slow dissociating antibodies from a display library, the library is contacted to an immobilized target. The immobilized target is then washed with a first solution that removes non—specifically or weakly bound biomolecules. Then the bound antibodies are eluted with a second solution that includes a saturating amount of free target or a target specific high—affinity competing monoclonal dy, i.e., replicates of the target that are not attached to the particle. The free target binds to biomolecules that dissociate from the target. Rebinding is effectively prevented by the saturating amount of free target relative to the much lower tration of immobilized target.

The second solution can have solution ions that are ntially physiological or that are stringent. Typically, the solution conditions of the second solution are identical to the solution conditions of the first solution. Fractions of the second solution are collected in temporal order to guish early from late fractions. Later fractions include biomolecules that dissociate at a slower rate from the target than biomolecules in the early fractions.

Further, it is also possible to recover display library members that remain bound to the target even after extended incubation. These can either be dissociated using chaotropic conditions or can be amplified while attached to the target. For example, phage bound to the target can be contacted to bacterial cells.

Selecting 0r Screening for Specificity. The display library screening methods described herein can include a selection or screening process that discards display library members that bind to a non—target le. es of non—target molecules include streptavidin on magnetic beads, blocking agents such as bovine serum n, non—fat 2012/040409 bovine milk, any ing or target lizing monoclonal antibody, or non—transfected cells which do not s the human FcRn target.

In one implementation, a so—called “negative selection” step is used to discriminate between the target and related non—target le and a related, but distinct rget molecules. The y library or a pool thereof is contacted to the non—target molecule.

Members of the sample that do not bind the non—target are collected and used in subsequent selections for binding to the target molecule or even for subsequent negative selections. The negative selection step can be prior to or after selecting library members that bind to the target molecule.

In another implementation, a screening step is used. After display library members are isolated for binding to the target molecule, each isolated library member is tested for its ability to bind to a non—target molecule (e.g., a non—target listed . For example, a high— throughput ELISA screen can be used to obtain this data. The ELISA screen can also be used to obtain quantitative data for binding of each library member to the target as well as for cross species reactivity to related targets or subunits of the target (e.g., rat FcRn; B2 microglobulin) and also under different condition such as pH6 or pH 7.5. The non—target and target binding data are ed (e.g., using a computer and software) to identify library members that specifically bind to the target.

Other Expression Libraries Other types of collections of proteins (e.g., expression libraries) can be used to fy proteins with a ular property (e.g., ability to bind FcRn and/or ability to modulate FcRn), including, e.g., protein arrays of antibodies (see, e.g., De Wildt et al. (2000) Nat. Biotechnol. 18:989—994), lambda gtll libraries, two—hybrid libraries and so forth.

Antibody Libraries In one embodiment, the library presents a diverse pool of polypeptides, each of which includes an immunoglobulin domain, e.g., an immunoglobulin variable domain. Display libraries are ularly useful, for example, for identifying human or “humanized” antibodies that recognize human antigens. Such antibodies can be used as therapeutics to treat human disorders such as autoimmune disorders. Because the constant and framework regions of the antibody are human, these therapeutic antibodies may avoid themselves being recognized and targeted as antigens. The constant regions may also be optimized to recruit effector functions of the human immune system. The in vitro display selection process surmounts the inability of a normal human immune system to generate antibodies against self—antigens.

A typical antibody display y ys a polypeptide that includes a VH domain and a VL domain. An “immunoglobulin ” refers to a domain from the variable or constant domain of immunoglobulin molecules. Immunoglobulin domains typically contain two B—sheets formed of about seven nds, and a conserved disulphide bond (see, 6.57., A.

F. Williams and A. N. Barclay, 1988, Ann. Rev. Immunol. 6:381—405). The display library can display the antibody as a Fab fragment (e.g., using two polypeptide chains) or a single chain Fv (e.g., using a single ptide chain). Other formats can also be used.

As in the case of the Fab and other formats, the displayed antibody can include one or more constant regions as part of a light and/or heavy chain. In one embodiment, each chain includes one constant region, 6.57., as in the case of a Fab. In other embodiments, onal constant regions are displayed.

Antibody libraries can be constructed by a number of processes (see, e.g., de Haard et al., 1999, J. Biol. Chem. 218—30; Hoogenboom et al., 1998, Immunotechnology 4:1—20; and Hoogenboom et al., 2000, Immunol. Today 21:371—378. Further, elements of each process can be combined with those of other processes. The processes can be used such that variation is uced into a single immunoglobulin domain (e.g., VH or VL) or into multiple immunoglobulin domains (e.g., VH and VL). The variation can be introduced into an immunoglobulin variable domain, 6.57., in the region of one or more of CDRl, CDR2, CDR3, FRl, FR2, FR3, and FR4, ing to such regions of either and both of heavy and light chain variable domains. In one ment, variation is introduced into all three CDRs of a given variable domain. In another embodiment, the variation is introduced into CDRl and CDR2, 6.57., of a heavy chain variable domain. Any combination is feasible. In one process, antibody libraries are constructed by inserting diverse oligonucleotides that encode CDRs into the corresponding regions of the nucleic acid. The oligonucleotides can be synthesized using monomeric nucleotides or trinucleotides. For example, Knappik et al., 2000, J. Mol.

Biol. 296:57—86 describe a method for ucting CDR encoding ucleotides using trinucleotide sis and a template with engineered restriction sites for accepting the oligonucleotides.

In another process, an animal, 6.57., a rodent, is immunized with the FcRn. The animal is optionally boosted with the antigen to further stimulate the response. Then spleen cells are isolated from the animal, and nucleic acid encoding VH and/or VL domains is amplified and cloned for expression in the display library.

In yet another process, antibody libraries are constructed from nucleic acid amplified from naive germline immunoglobulin genes. The ied nucleic acid includes nucleic acid ng the VH and/or VL domain. Sources of immunoglobulin—encoding c acids are described below. Amplification can include PCR, 6.57., with primers that anneal to the ved constant region, or another amplification method.

Nucleic acid encoding globulin domains can be ed from the immune cells of, 6.57., a human, a e, mouse, , camel, llama or rodent. In one example, the cells are selected for a particular property. B cells at various stages of maturity can be selected. In r example, the B cells are naive.

In one embodiment, fluorescent—activated cell sorting (FACS) is used to sort B cells that express surface—bound IgM, IgD, or IgG les. Further, B cells expressing different isotypes of IgG can be isolated. In another ment, the B or T cell is cultured in vitro.

The cells can be stimulated in vitro, 6.57., by culturing with feeder cells or by adding mitogens or other modulatory reagents, such as antibodies to CD40, CD40 ligand or CD20, phorbol myristate acetate, bacterial lipopolysaccharide, concanavalin A, phytohemagglutinin, or pokeweed mitogen.

In still one embodiment, the cells are isolated from a subject that has an autoimmune disorder, e.g., systemic lupus erythematosus (SLE), rheumatoid arthritis, vasculitis, Sjogren syndrome, systemic sclerosis, or anti—phospholipid syndrome. The subject can be a human, or an animal, 6.57., an animal model for the human disease, or an animal having an analogous disorder. In yet one embodiment, the cells are ed from a transgenic non—human animal that includes a human immunoglobulin locus.

In one embodiment, the cells have activated a program of somatic hypermutation.

Cells can be stimulated to undergo somatic mutagenesis of immunoglobulin genes, for example, by treatment with anti—immunoglobulin, anti—CD40, and D38 antibodies (see, e.g., Bergthorsdottir et al., 2001, J. Immunol. 166:2228). In one embodiment, the cells are naive.

The nucleic acid encoding an immunoglobulin variable domain can be isolated from a l repertoire by the following exemplary method. First, RNA is ed from the immune cell. Full length (i.e., capped) mRNAs are separated (e.g., by degrading uncapped RNAs with calf intestinal phosphatase). The cap is then removed with tobacco acid pyrophosphatase and reverse transcription is used to produce the cDNAs.

The reverse transcription of the first (antisense) strand can be done in any manner with any suitable primer. See, e.g., de Haard et al., 1999, J. Biol. Chem. 218—30. The primer binding region can be constant among different immunoglobulins, 6.57., in order to reverse transcribe different isotypes of immunoglobulin. The primer binding region can also be specific to a particular isotype of immunoglobulin. Typically, the primer is ic for a region that is 3’ to a sequence encoding at least one CDR. In one ment, poly—dT s may be used (and may be preferred for the heavy—chain genes).

A synthetic sequence can be ligated to the 3’ end of the reverse transcribed strand.

The synthetic sequence can be used as a primer g site for g of the forward primer during PCR amplification after reverse transcription. The use of the synthetic ce can obviate the need to use a pool of different forward primers to fully capture the available diversity.

The variable —encoding gene is then amplified, 6.57., using one or more rounds.

If multiple rounds are used, nested s can be used for increased fidelity. The amplified nucleic acid is then cloned into a display library vector.

Secondary Screening Methods After selecting ate library members that bind to a target, each candidate library member can be further analyzed, e.g., to further characterize its binding properties for the target. Each candidate y member can be subjected to one or more secondary screening assays. The assay can be for a binding property, a catalytic property, an inhibitory property, a physiological ty (e.g., cytotoxicity, renal nce, immunogenicity), a structural property (e.g., stability, conformation, oligomerization state) or another functional property.

The same assay can be used repeatedly, but with varying conditions, e.g., to determine pH, ionic, or thermal sensitivities.

As appropriate, the assays can use a display library member directly, a recombinant polypeptide produced from the nucleic acid encoding the selected polypeptide, or a synthetic peptide synthesized based on the ce of the selected polypeptide. ary assays for g properties include the following.

ELISA. Antibodies selected from an sion library can also be screened for a binding property using an ELISA. For example, each antibody is ted to a microtitre plate whose bottom surface has been coated with the target, e.g. , a limiting amount of the target. The plate is washed with buffer to remove non—specifically bound polypeptides. Then the amount of the antibody bound to the plate is determined by probing the plate with an antibody that can ize the test antibody, 6.57., a tag or constant portion of the antibody.

The detection dy is linked to an enzyme such as alkaline phosphatase or horse radish peroxidase (HRP) which produces a colorimetric product when appropriate substrates are In the case of an antibody from a display library, the antibody can be purified from cells or assayed in a display library format, 6.57., as a fusion to a filamentous bacteriophage coat. In r version of the ELISA, each dy selected from an expression library is used to coat a different well of a microtitre plate. The ELISA then proceeds using a constant target molecule to query each well.

Homogeneous Binding Assays. The binding interaction of candidate antibody with a target can be analyzed using a homogenous assay, i.e., after all components of the assay are added, additional fluid manipulations are not required. For example, fluorescence resonance energy transfer (FRET) can be used as a homogenous assay (see, for example, Lakowicz et al., US Patent No. 5,631,169; Stavrianopoulos, et al., US Patent No. 4,868,103). A fluorophore label on the first molecule (e.g., the molecule identified in the fraction) is selected such that its emitted fluorescent energy can be absorbed by a fluorescent label on a second molecule (e.g., the target) if the second molecule is in proximity to the first molecule.

The cent label on the second molecule fluoresces when it absorbs to the transferred energy. Since the efficiency of energy er between the labels is d to the distance separating the molecules, the spatial relationship between the molecules can be assessed. In a situation in which binding occurs between the molecules, the fluorescent emission of the tor’ molecule label in the assay should be maximal. A binding event that is configured for monitoring by FRET can be conveniently measured through standard fluorometric detection means well known in the art (e.g., using a fluorimeter). By titrating the amount of the first or second binding molecule, a g curve can be generated to estimate the equilibrium binding constant.

Another example of a homogenous assay is CREENTM (Packard Bioscience, Meriden CT). ALPHASCREEN TM uses two labeled beads. One bead generates singlet oxygen when excited by a laser. The other bead generates a light signal when singlet oxygen diffuses from the first bead and collides with it. The signal is only generated when the two beads are in proximity. One bead can be attached to the display library , the other to the target. Signals are ed to determine the extent of binding.

The homogenous assays can be performed while the candidate polypeptide is attached to the display library vehicle, 6.57., a bacteriophage.

Surface Plasmon Resonance (SPR). The binding interaction of a molecule isolated from an expression library and a target can be analyzed using SPR. SPR or Biomolecular Interaction Analysis (BIA) s biospecific interactions in real time, t labeling any of the interactants. Changes in the mass at the g surface ative of a binding event) of the BIA chip result in tions of the refractive index of light near the surface (the optical phenomenon of e plasmon resonance (SPR)). The changes in the refractivity generate a detectable signal, which are ed as an indication of real—time reactions between biological molecules. Methods for using SPR are described, for example, in US.

Patent No. 5,641,640; Raether, 1988, Surface Plasmons Springer Verlag; Sjolander and Urbaniczky, 1991, Anal. Chem. 63:2338—2345; Szabo et al., 1995, Curr. Opin. Struct. Biol. :699—705 and on—line resources provide by e International AB (Uppsala, Sweden).

Information from SPR can be used to provide an accurate and quantitative measure of the equilibrium dissociation constant (Kd), and kinetic ters, including K011 and Koff, for the binding of a biomolecule to a target. Such data can be used to compare different biomolecules. For example, selected proteins from an expression library can be compared to identify proteins that have high affinity for the target or that have a slow Koff. This information can also be used to develop structure—activity relationships (SAR). For example, the kinetic and brium binding parameters of matured versions of a parent n can be compared to the parameters of the parent protein. t amino acids at given positions can be identified that correlate with particular binding parameters, e.g. and slow , high affinity Koff. This information can be combined with structural modeling (e.g., using homology modeling, energy minimization, or structure determination by x—ray crystallography or WO 67039 NMR). As a , an understanding of the physical interaction between the protein and its target can be formulated and used to guide other design processes.

Cellular Assays. A library of candidate dies (e.g., preViously identified by a display library or otherwise) can be screened for target g on cells which transiently or stably express and display the target of interest on the cell surface. For example, the target can e vector c acid sequences that include segments that encode only the extracellular portion of the polypeptides such that the ic target polypeptides are produced within the cell, secreted from the cell, or attached to the cell surface through the anchor 6.57., in fusion with a membrane anchoring proteins such as PC. The cell surface expressed target can be used for ing dies that bind to FcRn and block the g of IgG—Fc. For example, non—specific human IgG—Fc could be fluorescently labeled and its binding to FcRn in the presence of absence of antagonistic antibody can be detected by a change in fluorescence intensity using flow cytometry 6.57., a FACS machine.

Other Methods for Obtaining FcRn—binding antibodies In addition to the use of display libraries, other methods can be used to obtain a FcRn— binding antibody. For example, the FcRn protein or a region thereof can be used as an antigen in a non—human animal, e. g., a rodent.

In one embodiment, the non—human animal includes at least a part of a human immunoglobulin gene. For example, it is possible to engineer mouse strains deficient in mouse dy production with large fragments of the human Ig loci. Using the hybridoma technology, antigen—specific monoclonal antibodies (Mabs) derived from the genes with the desired specificity may be ed and selected. See, e.g., XENOMOUSETM, Green et al., 1994, Nat. Gen. 7:13—21; U.S. 2003—0070185, WO 96/34096, published Oct. 31, 1996, and PCT Application No. PCT/US96/05928, filed Apr. 29, 1996.

In one embodiment, a monoclonal antibody is obtained from the non—human animal, and then modified, e.g., humanized or deimmunized. Winter describes a CDR—grafting method that may be used to prepare the humanized antibodies (UK Patent Application GB 2188638A, filed on March 26, 1987; US Patent No. 5,225,539. All of the CDRs of a particular human antibody may be replaced with at least a portion of a man CDR or only some of the CDRs may be replaced with non—human CDRs. It is only necessary to replace the number of CDRs required for binding of the humanized antibody to a ermined antigen. 2012/040409 Humanized antibodies can be generated by replacing ces of the Fv variable region that are not directly involved in antigen binding with equivalent sequences from human Fv variable regions. General methods for generating humanized antibodies are provided by Morrison, S. L., 1985, Science 229:1202—1207, by Oi et al., 1986, BioTechniques 4:214, and by Queen et al. US Patent Nos. 5,585,089, US 5,693,761 and US 5,693,762.

Those methods include isolating, manipulating, and expressing the nucleic acid sequences that encode all or part of immunoglobulin Fv variable regions from at least one of a heavy or light chain. Sources of such nucleic acid are well known to those skilled in the art and, for example, may be obtained from a hybridoma producing an antibody against a predetermined target, as bed above. The recombinant DNA encoding the humanized antibody, or fragment thereof, can then be cloned into an appropriate sion vector.

An FcRn—binding antibody may also be ed by specific deletion of human T cell epitopes or unization" by the methods disclosed in WO 98/52976 and WO 00/34317, the contents of which are specifically incorporated by reference herein. Briefly, the heavy and light chain le regions of an dy can be analyzed for peptides that bind to MHC Class 11; these peptides represent potential T—cell es (as defined in WO 98/52976 and WO 00/34317). For detection of potential T—cell epitopes, a computer modeling approach termed “peptide threading” can be applied, and in addition a database of human MHC class II g peptides can be searched for motifs present in the VH and VL sequences, as described in WO 98/52976 and WO 00/34317. These motifs bind to any of the 18 major MHC class 11 DR allotypes, and thus tute potential T cell epitopes. ial T—cell epitopes detected can be ated by substituting small numbers of amino acid residues in the variable s or by single amino acid substitutions. As far as possible conservative substitutions are made, often but not exclusively, an amino acid common at this position in human germline antibody sequences may be used. Human germline sequences are disclosed in Tomlinson, I.A. et al., 1992, J. Mol. Biol. 227:776—798; Cook, G. P. et al., 1995, Immunol.

Today Vol. 16 (5): 237-242; Chothia, D. et al., 1992, J. Mol. Bio. 9-817. The V BASE directory provides a comprehensive directory of human immunoglobulin variable region sequences (compiled by Tomlinson, I.A. et al. MRC Centre for Protein ering, Cambridge, UK). After the deimmunizing changes are identified, nucleic acids encoding VH and VL can be constructed by mutagenesis or other synthetic methods (e.g., de novo synthesis, cassette ement, and so forth). Mutagenized variable sequence can, optionally, be fused to a human constant region, e.g., human IgGl or K constant regions.

In some cases, a ial T cell epitope will include es which are known or predicted to be important for antibody function. For example, potential T cell es are usually biased towards the CDRs. In addition, potential T cell epitopes can occur in framework residues important for antibody structure and binding. Changes to eliminate these potential epitopes will in some cases require more scrutiny, 6.57., by making and g chains with and without the change. Where possible, potential T cell epitopes that overlap the CDRs were eliminated by substitutions outside the CDRs. In some cases, an alteration within a CDR is the only option, and thus variants with and without this substitution should be tested.

In other cases, the substitution required to remove a potential T cell epitope is at a residue position within the framework that might be critical for antibody binding. In these cases, variants with and without this substitution should be tested. Thus, in some cases several variant deimmunized heavy and light chain variable regions were designed and various heavy/light chain ations tested in order to identify the optimal deimmunized antibody.

The choice of the final deimmunized antibody can then be made by ering the binding affinity of the different ts in conjunction with the extent of deimmunization, i.e., the number of potential T cell epitopes remaining in the variable region. Deimmunization can be used to modify any antibody, 6.57., an antibody that es a non—human sequence, 6.57., a synthetic dy, a murine antibody other non—human monoclonal antibody, or an antibody isolated from a display library.

Germlining Antibodies.

An antibody used to treat an IgG—mediated autoimmune disease can be used for multiple administrations. tions that would lower the immunogenicity of the therapeutic antibody include reverting one or more non—germline amino acids in framework regions to corresponding germline amino acids (e.g., so long as binding properties are ntially retained) of the antibody (especially of Fabs).

It is possible to modify an antibody that binds FcRn, 6.57., an antibody described herein, in order to make the variable regions of the antibody more similar to one or more germline ces. For example, an antibody can include one, two, three, or more amino acid substitutions, 6.57., in a framework, CDR, or constant , to make it more similar to a reference germline sequence. One ary germlining method can include identifying one or more germline sequences that are r (e.g., most r in a particular database) to the ce of the isolated antibody. Mutations (at the amino acid level) can then be made in the isolated antibody, either incrementally or in combination with other mutations. For example, a nucleic acid library that includes sequences encoding some or all le germline mutations is made. The mutated antibodies are then evaluated, e.g., to identify an antibody that has one or more additional germline residues relative to the isolated antibody and that is still useful (e.g., has a functional activity). In one embodiment, as many germline residues are introduced into an isolated antibody as possible.

In one embodiment, mutagenesis is used to substitute or insert one or more germline residues into a framework and/or constant region. For example, a germline ork and/or constant region residue can be from a ne sequence that is similar (e.g., most similar) to the non—variable region being modified. After mutagenesis, activity (e.g., binding or other functional activity) of the antibody can be evaluated to determine if the germline residue or residues are tolerated (i.e., do not abrogate activity). Similar mutagenesis can be performed in the framework s.

Selecting a germline sequence can be performed in different ways. For example, a germline sequence can be selected if it meets a ermined ia for selectivity or similarity, 6.57., at least a certain percentage identity, 6.57., at least 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 99.5% ty. The selection can be performed using at least 2, 3, , or 10 ne sequences. In the case of CDRl and CDR2, identifying a similar germline ce can include selecting one such sequence. In the case of CDR3, identifying a similar germline sequence can include selecting one such sequence, but may including using two germline sequences that separately contribute to the terminal portion and the carboxy— terminal portion. In other entations more than one or two germline sequences are used, 6.57., to form a consensus sequence.

In one ment, with respect to a particular reference variable domain sequence, 6.57., a sequence described herein, a related variable domain sequence has at least 30, 40, 50, 60, 70, 80, 90, 95 or 100% of the CDR amino acid positions that are not identical to residues in the reference CDR sequences, residues that are identical to residues at corresponding positions in a human germline sequence (i.e., an amino acid sequence encoded by a human germline nucleic acid).

W0 2012/167039 In one embodiment, with respect to a particular reference variable domain sequence, 6.57., a sequence described herein, a related variable domain sequence has at least 30, 50, 60, 70, 80, 90 or 100% of the FR regions are identical to FR sequence from a human germline sequence, 6.57., a germline sequence related to the reference variable domain sequence.

Accordingly, it is possible to isolate an antibody which has r activity to a given dy of interest, but is more similar to one or more germline sequences, particularly one or more human germline ces. For example, an antibody can be at least 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 99.5% identical to a germline sequence in a region outside the CDRs (e.g., framework regions). Further, an antibody can include at least 1, 2, 3, 4, or 5 germline residues in a CDR region, the germline residue being from a germline sequence of similar (e.g., most similar) to the variable region being ed. Germline sequences of primary st are human germline sequences. The activity of the antibody (e.g., the binding activity) can be Within a factor or 100, 10, 5, 2, 0.5, 0.1, and 0.001 of the original antibody.

Exemplary germline reference ces for Vkappa include: , 018/08, A20, A30, L14, L1, L15, L4/18a, L5/L19, L8, L23, L9 ,L24, L11, L12, 011/01, A17, A1, A18, A2, A19/A3, A23, A27, A11, , L6, L20, L25, B3, B2, 0, and A14. See, e.g., Tomlinson et al., 1995, EMBO J. :4628—3.

A germline reference sequence for the HC variable domain can be based on a sequence that has particular canonical structures, 6.57., 1—3 structures in the H1 and H2 hypervariable loops. The canonical structures of hypervariable loops of an immunoglobulin variable domain can be inferred from its sequence, as described in Chothia et al., 1992, J.

M01. Biol. 227:799—817; Tomlinson et al., 1992, J. M01. Biol. 227:776—798); and son et al., 1995, EMBO J. 14(18):4628—38. Exemplary sequences with a 1—3 structure include: DP-l, DP-8, DP-12, DP-2, DP-25, DP-15, DP-7, DP-4, DP-31, DP-32, DP-33, DP-35, DP- 40, 7—2, hv3005, hv3005f3, DP-46, DP-47, DP-58, DP-49, DP-50, DP-51, DP-53, and DP-54.

Ligand Production Standard recombinant nucleic acid methods can be used to express an antibody that binds to FcRn. Generally, a nucleic acid sequence encoding the dy is cloned into a nucleic acid expression vector. Of course, if the dy includes multiple polypeptide , each chain can be cloned into an expression vector, 6.57., the same or different vectors, that are expressed in the same or different cells.

Antibody Production. Some antibodies, e.g., Fabs, can be produced in bacterial cells, 6.57., E. coli cells. For example, if the Fab is encoded by sequences in a phage display vector that includes a suppressible stop codon between the y entity and a bacteriophage protein (or nt thereof), the vector nucleic acid can be transferred into a bacterial cell that cannot ss a stop codon. In this case, the Fab is not fused to the gene III protein and is secreted into the periplasm and/or media.

Antibodies can also be produced in eukaryotic cells. In one embodiment, the dies (e.g., scFv’s) are sed in a yeast cell such as Pichia (see, e.g., Powers et al., 2001, J. Immunol. Methods. 3—35), Hanseula, or Saccharomyces.

In one embodiment, antibodies are produced in mammalian cells. Mammalian host cells for expressing the clone antibodies or antigen—binding fragments thereof include Chinese Hamster Ovary (CHO cells) (including dhfr— CHO cells, described in Urlaub and Chasin, 1980, Proc. Natl. Acad. Sci. USA 77:4216—4220, used with a DHFR selectable marker, 6.57., as described in Kaufman and Sharp, 1982, M01. Biol. 159:601 621), lymphocytic cell lines, e.g., NSO myeloma cells and SP2 cells, COS cells, and a cell from a transgenic animal, 6.57., a transgenic mammal. For e, the cell is a mammary epithelial cell.

In on to the nucleic acid sequence encoding the diversified immunoglobulin domain, the inant expression vectors may carry additional sequences, such as sequences that regulate replication of the vector in host cells (e.g., origins of replication) and selectable marker genes. The selectable marker gene facilitates selection of host cells into which the vector has been introduced (see 6.57., US. Patent Nos. 4,399,216, 4,634,665 and ,179,017). For example, typically the selectable marker gene confers resistance to drugs, such as G418, hygromycin or methotrexate, on a host cell into which the vector has been introduced. able marker genes include the dihydrofolate reductase (DHFR) gene (for use in dhfr' host cells with methotrexate selection/amplification) and the neo gene (for G418 selection).

In an exemplary system for recombinant expression of an antibody, or antigen— binding portion thereof, a recombinant sion vector encoding both the dy heavy chain and the antibody light chain is introduced into dhfr' CHO cells by calcium phosphate— mediated transfection. Within the recombinant expression vector, the antibody heavy and light chain genes are each ively linked to enhancer/promoter regulatory elements (e.g., derived from SV40, CMV, adenovirus and the like, such as a CMV enhancer/AdMLP promoter regulatory element or an SV40 enhancer/AdMLP er regulatory element) to drive high levels of transcription of the genes. The inant expression vector also carries a DHFR gene, which allows for selection of CHO cells that have been transfected with the vector using methotrexate selection/amplification. The selected transformant host cells are cultured to allow for expression of the antibody heavy and light chains and intact antibody is recovered from the culture . Standard molecular biology techniques are used to prepare the recombinant expression vector, transfect the host cells, select for transformants, culture the host cells and r the antibody from the culture medium. For example, some antibodies can be isolated by affinity chromatography with a Protein A or Protein G coupled matrix.

For antibodies that include an Fc domain, the antibody production system may produce antibodies in which the Fc region is glycosylated. For e, the Fc domain of IgG molecules is ylated at asparagine 297 in the CH2 domain. This asparagine is the site for modification with biantennary—type oligosaccharides. It has been trated that this glycosylation is ed for effector functions mediated by ch receptors and complement Clq (Burton and Woof, 1992, Adv. Immunol. 51:1—84; Jefferis et al., 1998, Immunol. Rev. 163:59—76). In one embodiment, the Fc domain is produced in a ian expression system that appropriately glycosylates the residue ponding to asparagine 297. The PC domain can also include other eukaryotic post—translational modifications.

Antibodies can also be produced by a transgenic animal. For example, US. Patent No. 5,849,992 describes a method of expressing an antibody in the mammary gland of a enic mammal. A transgene is constructed that includes a milk—specific promoter and nucleic acids encoding the antibody of interest and a signal sequence for secretion. The milk produced by females of such transgenic mammals includes, secreted—therein, the antibody of interest. The antibody can be purified from the milk, or for some applications, used directly.

One method for producing a transgenic mouse is as follows. Briefly, a targeting construct that encodes the antibody is njected into the male pronucleus of fertilized oocytes. The oocytes are injected into the uterus of a pseudopregnant foster mother for the development into viable pups. Some offspring incorporate the transgene.

Assay Systems for FcRn Candidate Antibodies FcRn candidate antibodies can be further characterized in assays that measure their modulatory activity toward FcRn or fragments thereof in vitro or in viva. For example, FcRn can be combined with a substrate such as non—specific IgG or Fc portion of the IgG or albumin under assay conditions permitting reaction of the FcRn with the ate. The assay is performed in the absence of the FcRn candidate antibody, and in the presence of increasing concentrations of the FcRn candidate antibody. The concentration of candidate antibody at which 50% of the FcRn activity (e.g., binding to the substrate) is ted by the candidate antibody is the IC50 value (Inhibitory Concentration 50%) or EC50 tive Concentration 50%) value for that antibody. Within a series or group of ate antibodies, those having lower IC50 or EC50 values are considered more potent inhibitors of FcRn than those dies having higher IC50 or EC50 values. In some embodiments, antibodies have an IC50 value of 800 nM, 400 nM, 100 nM, 25 nM, 5 nM, 1 nM, or less as ed in an in vitro assay for inhibition of FcRn activity.

The candidate antibodies can also be ted for selectivity toward FcRn. For example, a FcRn candidate antibody can be assayed for its potency toward FcRn and a panel of cell surface receptors, such as receptors that also utilize the BZM domain, and an IC50 value or EC50 value can be determined for each receptor protein. In one ment, a compound that demonstrates a low IC50 value or EC50 value for the FcRn, and a higher IC50 value or EC50 value for other receptors within the test panel (6. g., MHC class I molecules) is considered to be selective toward FcRn.

Ex vivo endothelial cells or epithelial cells expressing the endogenous FcRn could be used to follow the tosis or transcytosis of the candidate antibodies under different pH and temperature conditions. IgG transcytosis or recycling by FcRn can be measured by ing a labeled antibody in the presence or absence of various chemicals and under different conditions that are known to influence or affect the intracellular trafficking pathway.

A pharmacokinetics study in rat, mice, or monkey could be performed with pH dependent and independent FcRn binding antibodies for ining their half—life in the serum. Likewise, the protective effect of the antibody can be assessed in viva for potential use in immunomodulating therapy or as an salvage immunotherapy by ing the antibody in the presence or absence of a labeled IgG or the labeled Fc portion of the IgG. A decrease in the half—life of the d IgG/Fc in the presence of the ate antibody is an indication of the therapeutic efficacy of the antibody.

Pharmaceutical Compositions In another aspect, the disclosure provides compositions, e.g., pharmaceutically acceptable itions or pharmaceutical compositions, which e an FcRn—binding antibody. The FcRn—binding antibody can be formulated together with a pharmaceutically acceptable carrier. Pharmaceutical compositions include eutic compositions and diagnostic compositions, e.g., compositions that include labeled FcRn—binding dies for in viva imaging.

A pharmaceutically acceptable carrier includes any and all solvents, sion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like that are physiologically compatible. Preferably, the carrier is suitable for intravenous, intramuscular, subcutaneous, parenteral, spinal, or epidermal administration (e.g., by injection or infusion). Depending on the route of stration, the FcRn—binding antibody may be coated in a al to protect the compound from the action of acids and other natural conditions that may vate the compound.

A pharmaceutically acceptable salt is a salt that s the desired biological activity of the parent compound and does not impart any undesired toxicological effects (see e.g., Berge, S.M., et al., 1977, J. Pharm. Sci. 66:1—19). Examples of such salts e acid addition salts and base on salts. Acid addition salts include those derived from nontoxic inorganic acids, such as hydrochloric, nitric, phosphoric, sulfuric, hydrobromic, hydroiodic, phosphorous, and the like, as well as from nontoxic organic acids such as aliphatic mono— and dicarboxylic acids, phenyl—substituted alkanoic acids, hydroxy alkanoic acids, aromatic acids, aliphatic and aromatic sulfonic acids, and the like. Base addition salts e those derived from alkaline earth metals, such as sodium, potassium, magnesium, calcium, and the like, as well as from nontoxic organic amines, such as N,N'—dibenzylethylenediamine, N— methylglucamine, chloroprocaine, choline, diethanolamine, ethylenediamine, procaine, and the like.

The compositions may be in a variety of forms. These include, for example, liquid, semi—solid and solid dosage forms, such as liquid solutions (e.g., injectable and infusible solutions), dispersions or suspensions, tablets, pills, powders, liposomes and suppositories.

The form can depend on the intended mode of administration and therapeutic application.

Many itions are in the form of injectable or infusible solutions, such as compositions similar to those used for administration of humans with antibodies. An exemplary mode of administration is parenteral (e.g., intravenous, aneous, intraperitoneal, intramuscular).

In one embodiment, the FcRn—binding antibody is administered by intravenous infusion or injection. In another embodiment, the inding dy is administered by uscular or subcutaneous injection.

The ition can be formulated as a solution, microemulsion, dispersion, me, or other ordered structure suitable to high drug concentration. e injectable solutions can be prepared by incorporating the active compound (i.e., the ) in the required amount in an appropriate solvent with one or a combination of ingredients ated above, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the active compound into a sterile vehicle that contains a basic dispersion medium and the required other ingredients from those enumerated above. In the case of e powders for the preparation of sterile injectable solutions, the methods of preparation are vacuum drying and freeze—drying that yields a powder of the active ingredient plus any additional desired ingredient from a previously sterile—filtered on thereof. The proper fluidity of a solution can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. Prolonged absorption of injectable compositions can be brought about by including in the composition an agent that delays absorption, for example, earate salts and gelatin.

An FcRn—binding antibody can be administered by a variety of methods known in the art, although for many applications, the route/mode of administration is intravenous injection or infusion. For example, for therapeutic applications, the FcRn—binding dy can be administered by intravenous infusion at a rate of less than 30, 20, 10, 5, or 1 mg/min to reach a dose of about 1 to 100 mg/m2 or 7 to 25 mg/m2. The route and/or mode of administration will vary depending upon the desired results. In certain embodiments, the active compound may be ed with a carrier that will protect the compound against rapid release, such as a controlled release formulation, including implants, and microencapsulated delivery systems.

Biodegradable, biocompatible polymers can be used, such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Many methods for the preparation of such formulations are patented or generally known. See, e.g., Sustained and Controlled Release Drug ry Systems, J .R. Robinson, ed., 1978, Marcel , Inc., New York.

In certain embodiments, the antibody may be orally administered, for example, with an inert diluent or an lable edible carrier. The compound (and other ingredients, if d) may also be enclosed in a hard or soft shell gelatin capsule, compressed into tablets, or incorporated directly into the subject's diet. For oral therapeutic administration, the compounds may be incorporated with excipients and used in the form of ingestible tablets, buccal tablets, troches, capsules, elixirs, suspensions, syrups, wafers, and the like. To administer a compound disclosed herein by other than parenteral administration, it may be ary to coat the compound with, or co—administer the nd with, a material to t its inactivation.

Pharmaceutical compositions can be administered with medical devices known in the art. For example, in one embodiment, a pharmaceutical composition disclosed herein can be administered with a device, e.g., a needleless hypodermic injection , a pump, or implant.

In certain ments, an FcRn—binding antibody can be formulated to ensure proper distribution in viva. For e, the blood—brain barrier (BBB) excludes many highly hilic compounds. To ensure that the therapeutic compounds disclosed herein cross the BBB (if desired), they can be formulated, for example, in liposomes. For s of manufacturing mes, see, e.g., US. Patent Nos. 4,522,811; 5,374,548; and 5,399,331.

The liposomes may comprise one or more moieties that are selectively orted into specific cells or organs, thus enhance targeted drug delivery (see, e.g., V.V. Ranade, 1989, J.

Clin. Pharmacol. 29:685).

Dosage regimens are adjusted to provide the optimum desired se (e.g., a therapeutic response). For example, a single bolus may be administered, several divided doses may be administered over time or the dose may be proportionally reduced or increased as indicated by the exigencies of the therapeutic situation. It is especially advantageous to formulate parenteral compositions in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form as used herein refers to physically discrete units suited as unitary dosages for the subjects to be treated; each unit contains a predetermined quantity of active compound calculated to produce the desired therapeutic effect in ation with the required pharmaceutical carrier. The specification for the dosage unit forms can be dictated by and directly dependent on (a) the unique characteristics of the active compound and the particular therapeutic effect to be achieved, and (b) the limitations inherent in the art of compounding such an active compound for the treatment of sensitivity in individuals.

An exemplary, non—limiting range for a therapeutically or prophylactically effective amount of an antibody disclosed herein is 0.1—20 mg/kg, or 1—10 mg/kg. An anti—FcRn antibody can be administered, e.g., by intravenous infusion, e.g., at a rate of less than 30, 20, , 5, or 1 mg/min to reach a dose of about 1 to 100 mg/m2 or about 5 to 30 mg/m2. Dosage values may vary with the type and severity of the condition to be alleviated. For a particular subject, specific dosage regimens can be adjusted over time according to the individual need and the sional judgment of the person administering or supervising the administration of the compositions.

The pharmaceutical compositions disclosed herein may include a therapeutically effective amount or a prophylactically effective amount of an FcRn—binding dy disclosed herein. A “therapeutically effective amount” refers to an amount effective, at dosages and for periods of time necessary, to e the d therapeutic result. A therapeutically effective amount of the composition may vary according to factors such as the e state, age, sex, and weight of the dual, and the ability of the antibody to elicit a desired response in the individual. A therapeutically effective amount is also one in which any toxic or detrimental effects of the composition is outweighed by the therapeutically beneficial effects.

Stabilization and Retention In one embodiment, an FcRn—binding antibody is physically ated with a moiety that improves its stabilization and/or retention in circulation, e.g., in blood, serum, lymph, or other tissues, e.g., by at least 1.5, 2, 5, 10, or 50 fold. For example, an FcRn—binding antibody can be associated with a polymer, e.g., a substantially non—antigenic polymers, such as polyalkylene oxides or polyethylene oxides. le rs will vary substantially by weight. Polymers having molecular number average weights ranging from about 200 to about 35,000 (or about 1,000 to about 15,000, and 2,000 to about 12,500) can be used. For e, an FcRn—binding dy can be conjugated to a water soluble polymer, e.g., WO 67039 hydrophilic polyvinyl polymers, e.g. polyvinylalcohol and polyvinylpyrrolidone. A non— limiting list of such polymers include polyalkylene oxide homopolymers such as polyethylene glycol (PEG) or polypropylene glycols, polyoxyethylenated polyols, copolymers thereof and block copolymers thereof, provided that the water solubility of the block copolymers is ined.

An FcRn—binding antibody described herein can be provided in a kit, e.g., as a component of a kit. For example, the kit es (a) an FcRn—binding antibody, e.g., a composition that includes an FcRn—binding antibody, and, optionally (b) informational material. The informational material can be descriptive, instructional, marketing or other material that s to the methods described herein and/or the use of an FcRn—binding dy for the methods described .

The informational material of the kits is not limited in its form. In one embodiment, the informational material can e information about production of the nd, molecular weight of the compound, concentration, date of expiration, batch or production site information, and so forth. In one embodiment, the informational material relates to using the antibody to treat, t, or diagnosis a disorder described herein, e.g., an autoimmune disorder.

In one embodiment, the informational material can include instructions to administer an FcRn—binding antibody in a le manner to m the methods bed herein, e.g., in a suitable dose, dosage form, or mode of administration (e.g., a dose, dosage form, or mode of administration described herein). In one embodiment, the informational material can include instructions to administer an FcRn—binding antibody to a suitable subject, e.g., a human, e.g., a human having, or at risk for, an autoimmune disorder (e.g., rheumatoid arthritis or systemic lupus matosis). For example, the material can include instructions to administer an FcRn—binding antibody to a patient with lupus or a patient with another autoimmune disorder.

The informational material of the kits is not limited in its form. In many cases, the ational material, e.g. is provided in printed matter, e.g., a printed text, , instructions, drawing, and/or photograph, e.g., a label or printed sheet. However, the informational material can also be provided in other formats, such as computer le material, video WO 67039 recording, or audio recording. In one embodiment, the ational material of the kit is contact information, 6.57., a physical address, email s, website, or telephone number, Where a user of the kit can obtain substantive information about an FcRn—binding antibody and/or its use in the s described . Of course, the informational material can also be provided in any combination of s.

In addition to an FcRn—binding antibody, the composition of the kit can include other ingredients, such as a t or buffer, a stabilizer, a preservative, a flavoring agent (e.g., a bitter antagonist or a sweetener), a fragrance or other ic ingredient, and/or a second agent for ng an mune disorder described herein, e.g. , rheumatoid arthritis or systemic lupus erythematosis. Alternatively, the other ients can be included in the kit, but in different compositions or containers than an FcRn—binding antibody. In such embodiments, the kit can include instructions for admixing an FcRn—binding dy and the other ingredients, or for using an FcRn—binding antibody together with the other ingredients.

An FcRn—binding antibody can be provided in any form, e.g., liquid, dried or lyophilized form. It is preferred that an FcRn—binding antibody be substantially pure and/or sterile. When an FcRn—binding antibody is provided in a liquid solution, the liquid solution preferably is an aqueous solution, with a sterile aqueous solution being preferred. When an FcRn—binding antibody is provided as a dried form, reconstitution generally is by the addition of a suitable solvent. The solvent, e.g., sterile water or buffer, can optionally be provided in the kit.

The kit can include one or more containers for the composition containing an FcRn— binding antibody. In some embodiments, the kit contains separate ners, dividers or compartments for the composition and informational material. For example, the composition can be contained in a bottle, vial, or syringe, and the informational material can be contained in a plastic sleeve or packet. In other embodiments, the separate elements of the kit are contained Within a single, undivided container. For example, the composition is contained in a bottle, vial or syringe that has attached thereto the informational al in the form of a label. In some embodiments, the kit includes a plurality (e.g., a pack) of individual containers, each ning one or more unit dosage forms (e.g., a dosage form described herein) of an FcRn—binding antibody. For example, the kit es a plurality of syringes, ampules, foil packets, or blister packs, each containing a single unit dose of an FcRn—binding dy. The ners of the kits can be air tight, waterproof (e.g., impermeable to changes in moisture or evaporation), and/or light—tight.

The kit optionally includes a device suitable for administration of the composition, e.g., a syringe, inhalant, pipette, forceps, measured spoon, dropper (e.g., eye dropper), swab (e.g., a cotton swab or wooden swab), or any such delivery device. In one embodiment, the device is an implantable device that dispenses metered doses of the antibody. The disclosure also features a method of providing a kit, e.g., by ing components described .

Treatments Antibodies that bind to FcRn and identified by the method described herein and/or detailed herein have therapeutic and prophylactic utilities. These dies can be administered to a subject to treat, prevent, and/or diagnose a variety of disorders, including autoimmune disorders, or even to cells in culture, e.g., in vitro or ex vivo.

The term “treating” refers to administering a therapy in an amount, manner, and/or mode effective to improve a condition, m, or parameter associated with a disorder or to prevent progression of a disorder, to either a statistically significant degree or to a degree detectable to one skilled in the art. An effective amount, manner, or mode can vary depending on the subject and may be tailored to the subject. The subject can be a human or a non—human animal, e.g., a man mammal.

The FcRn—binding antibody can be administered in a therapeutically effective amount, e.g., such that upon single or multiple dose administration to a t, the subject exhibits an amelioration of symptoms of a disorder, e.g., an mune disorder (e.g., toid tis or systemic lupus erythematosis) or of a parameter indicative of ce or risk for the disorder.

Exemplary disorders which affect many organs or localized organs in the body include: Multiple Sclerosis, rheumatoid arthritis, inflammatory bowel diseases (IBD), lupus, and ankylosing spondylitis. Some of these disorders are discussed below. In one aspect, the invention provides s for the treatment of cancer. Still other disorders that can be treated using an FcRn—binding dy include: scleroderma, Sjogren’s syndrome, Goodpasture’s syndrome, Wegener’s granulomatosis, polymyalgia rheumatica, temporal arteritis /gian cell arteritis, ia areata, anklosing spondylitis, antiphospholipid syndrome, autoimmune Addison’s disease, mune hemolytic anemia, autoimmune hepatitis, autoimmune inner ear disease, autoimmune lymphoproliferative syndrome (ALPS), autoimmune thrombocytopenic purpura (ATP), Behcet’s disease, bullous pemphigoid, cardiomyopathy, celiac sprue—dermatitis, chronic fatigue syndrome immune deficiency syndrome (CFIDS), chronic inflammatory demyelinating uropathy, cicatricial pemphigoid, cold agglutinin disease, CREST Syndrome, Crohn’s e, Dego’s disease, dermatomyositis, juvenile dermatomyositis, discoid lupus, essential mixed cryoglobulinemia, fibromyalgia, fibromyositis, Grave’s disease, in—Barre syndrome, Hashimoto’s thyroiditis, idiopathic pulmonary fibrosis, idiopathic thrombocytopenia purpura (ITP), IgA nephropathy, insulin dependent diabetes (Type I), le arthritis, Meniere’s disease, mixed connective tissue disease, myasthenia gravis, gus vulgaris, pemphigus foliaceus, paraneoplastic pemphigus, pernicious anemia, polyarteritis nodosa, polychondritis, ancular syndromes , polymyalgia rheumatica, polymyositis, dermatomyositis, primary agammaglobulinemia, y biliary cirrhosis, psoriasis, Raynaud’s phenomenon, Reiter’s syndrome, rheumatic fever, sarcoidosis, stiff—man syndrome, Takayasu arteritis, tive colitis, uveitis, vasculitis, vitiligo.

In some embodiments, the anti—FcRn binding antibody is administered to remove an unwanted eutic antibody from the bloodstream.

In some embodiments, the anti—FcRn binding antibody is administered to suppress the level of anti—HLA antibodies. In some embodiments the level of anti—HLA antibodies is suppressed in connection with organ lant.

Methods of administering inding antibodies are described in “Pharmaceutical Compositions.” Suitable dosages of the molecules used will depend on the age and weight of the subject and the particular drug used. The antibodies can be used as competitive agents to inhibit or reduce an undesirable interaction, 6.57., between a natural or ogical agent and the FcRn.

The FcRn g antibody can be used to deliver macro and micromolecules, 6.57., a gene into the cell for gene therapy purposes into the endothelium or lium and target only those tissues expressing the FcRn. The antibodies may be used to deliver a variety of cytotoxic drugs including eutic drugs, a compound emitting radiation, molecules of plants, fungal, or bacterial origin, biological proteins, and mixtures thereof. The cytotoxic drugs can be intracellularly acting cytotoxic drugs, such as short range radiation emitters, ing, for e, short range, high energy tters, as described herein.

In the case of polypeptide toxins, recombinant nucleic acid ques can be used to construct a c acid that encodes the antibody and the cytotoxin (or a polypeptide component thereof) as translational fusions. The recombinant nucleic acid is then expressed, e. g., in cells and the encoded fusion polypeptide isolated.

Alternatively, the FcRn—binding antibody can be coupled to high energy radiation _ . . 131 emitters, for example, a radioisotope, such as I, a y—emitter, which, when localized at a site, results in a killing of several cell diameters. See, e. 57., SE. Order, “Analysis, Results, and Future Prospective of the Therapeutic Use of Radiolabeled Antibody in Cancer Therapy”, Monoclonal dies for Cancer ion and Therapy, R.W. Baldwin et al. (eds.), pp 303 316 (Academic Press 1985). Other suitable sotopes include a emitters, such as 212Bi, 213Bi, and 211At, and b emitters, such as 186Re and 90Y. W Moreover, Lu may also be used as both an imaging and cytotoxic agent.

Radioimmunotherapy (RIT) using antibodies labeled with 131I ,90Y, and 177Lu is under intense clinical investigation. There are significant differences in the physical characteristics of these three nuclides and as a result, the choice of radionuclide is very al in order to deliver maximum ion dose to a tissue of interest. The higher beta energy particles of 90Y may be good for bulky tumors. The relatively low energy beta les of 131I are ideal, but in vivo dehalogenation of radioiodinated molecules is a major disadvantage for internalizing dy. In st, 177Lu has low energy beta particle with only 0.2—0.3 mm range and delivers much lower radiation dose to bone marrow compared to 90Y. In addition, due to longer physical half—life (compared to 90Y), the residence times are higher. As a result, higher activities (more mCi amounts) of 177Lu labeled agents can be administered with comparatively less ion dose to marrow. There have been several clinical studies investigating the use of 177Lu labeled antibodies in the treatment of various cancers.

(Mulligan T et al., 1995, Clin. Canc. Res. 1: 1447—1454; Meredith RF, et al., 1996, J. Nucl.

Med. 37:1491—1496; Alvarez RD, et al., 1997, Gynecol. Oncol. 65: 94—101).

Use of the therapeutic methods to treat autoimmunity has a number of benefits. Since the antibodies specifically recognize FcRn, other tissue is spared and high levels of the agent are delivered directly to the site where therapy is required. Treatment can be effectively red with clinical parameters. Alternatively, these parameters can be used to te when such treatment should be employed.

WO 67039 An FcRn—binding antibody can be administered in combination with one or more of the existing modalities for treating mune disorders including, but not d to: intravenous lg therapy, nonsteroidal anti—inflammatory drugs (NSAID), and osteroids; and anti—inflammatory treatments such as cyclosporins, rapamycins or cins, or their immunosuppressive analogs, e.g., cyclosporin A, cyclosporin G, FK—506, rapamycin, 40—O— (2—hydroxy)ethyl—rapamycin etc.; cyclophosphamide; azathioprene; methotrexate; brequinar; FTY 720; leflunomide; mnizoribine; mycophenolic acid; mycophenolate mofetil; 15— deoxyspergualine; immunosuppressive monoclonal antibodies, e.g., monoclonal antibodies to leukocyte receptors, e.g., MHC, CD2, CD3, CD4, CD7, CD25, CD28, B7, CD45, or CD58 or their ligands; or other immunomodulatory compounds, e. g., CTLA4lg, or other adhesion molecule tors, e.g. mAbs or low molecular weight inhibitors including selectin antagonists and VLA—4 antagonists. These combination ies can be part of an immunomodulating regimens or a regimen for the treatment or tion of allo— or xenograft acute or chronic rejection, an inflammatory disorder, or an autoimmune disorders.

Multiple Sclerosis le sclerosis (MS) is a central s system disease that is characterized by inflammation and loss of myelin s.

Patients having MS may be identified by criteria ishing a diagnosis of clinically definite MS as defined by the workshop on the diagnosis of MS (Poser et al., Ann. Neurol. 13:227, 1983). MS may also be diagnosed by evidence of two attacks and oligoclonal bands of IgG in cerebrospinal fluid or by combination of an attack, clinical evidence of two lesions and oligoclonal band of IgG in cerebrospinal fluid. The McDonald criteria can also be used to diagnose MS. McDonald et al.(200l) Recommended diagnostic criteria for multiple sclerosis: guidelines from the International Panel on the Diagnosis ofMultiple Sclerosis, Ann Neurol 50:121—127. The McDonald criteria include the use of MRI evidence of CNS ment over time to be used in diagnosis of MS, in the absence of le clinical attacks.

Effective treatment of multiple sclerosis may be evaluated in several different ways.

The following parameters can be used to gauge effectiveness of ent. Two exemplary criteria include: EDSS (extended disability status scale), and appearance of exacerbations on MRI (magnetic resonance imaging). The EDSS is a means to grade clinical impairment due 2012/040409 to MS (Kurtzke, Neurology 33: 1444, 1983). Eight functional systems are evaluated for the type and severity of neurologic impairment. Briefly, prior to treatment, patients are evaluated for impairment in the following systems: pyramidal, cerebella, brainstem, y, bowel and bladder, visual, cerebral, and other. Follow—ups are conducted at defined intervals. The scale ranges from 0 (normal) to 10 (death due to MS). A decrease of one full step can indicate an effective ent ke, Ann. Neurol. 36:573-79, 1994).

Exemplary symptoms associated with multiple sclerosis, which can be treated with the methods described herein, e: optic neuritis, diplopia, nystagmus, ocular dysmetria, internuclear ophthalmoplegia, movement and sound phosphenes, nt pupillary defect, paresis, monoparesis, paraparesis, hemiparesis, quadraparesis, plegia, paraplegia, hemiplegia, tetraplegia, quadraplegia, spasticity, dysarthria, muscle atrophy, spasms, cramps, hypotonia, , nus, myokymia, restless leg syndrome, footdrop, ctional reflexes, paraesthesia, anaesthesia, neuralgia, neuropathic and enic pain, l'hermitte's, proprioceptive dysfunction, trigeminal neuralgia, ataxia, intention tremor, dysmetria, vestibular ataxia, vertigo, speech ataxia, dystonia, dochokinesia, frequent micturation, bladder spasticity, flaccid bladder, detrusor—sphincter dyssynergia, erectile dysfunction, anorgasmy, frigidity, constipation, fecal urgency, fecal incontinence, depression, cognitive dysfunction, dementia, mood swings, emotional lability, euphoria, bipolar me, anxiety, aphasia, dysphasia, fatigue, fs symptom, gastroesophageal reflux, and sleeping ers.

In addition to or prior to human studies, an animal model can be used to evaluate the efficacy of using the two agents. An exemplary animal model for multiple sclerosis is the experimental autoimmune encephalitis (EAE) mouse model, e.g., as described in (Tuohy et al. (J. Immunol. (1988) 141: 1126-1130), Sobel et al. (J. Immunol. (1984) 132: 2393-2401), and Traugott (Cell Immunol. (1989) 119: 9). Mice can be administered a first and second agent described herein prior to EAE induction. Then the mice are evaluated for characteristic criteria to determine the cy of using the two agents in the model.

Inflammatory Bowel Disease Inflammatory bowel diseases (IBD) include generally chronic, relapsing intestinal inflammation. IBD refers to two ct disorders, Crohn's disease and ulcerative colitis (UC). The clinical symptoms of IBD include intermittent rectal bleeding, crampy abdominal pain, weight loss and diarrhea. A clinical index can also be used to monitor IBD such as the Clinical Activity Index for Ulcerative Colitis. See also, Walmsley et al. Gut. 1998 Jul;43(l):29—32 and Jowett et al. (2003) Scand J Gastroenterol. 38(2):l64—7l. An FcRn— binding antibody can be used to ameliorate at least one symptom of IBD or to ameliorate a clinical index of IBD.

Rheumatoid Arthritis Rheumatoid arthritis is an autoimmune inflammatory disease that causes pain, swelling, stiffness, and loss of function in the . Rheumatoid arthritis often presents in a symmetrical pattern. The disease can affect the wrist joints and the finger joints closest to the hand. It can also affect other parts of the body besides the joints. In addition, people with rheumatoid arthritis may have e, occasional fevers, and a general malaise. Positive factors for sis of rheumatoid arthritis include the “rheumatoid ” blood antibody and citrulline antibody. An FcRn—binding antibody can be useful in treating, preventing, or alleviating rheumatoid arthritis or one or more symptoms of rheumatoid arthritis.

Lupus Systemic lupus erythematosus (SLE) is an autoimmune disorder that leads to inflammation and damage to various body tissues. SLE can be mediated by ntibodies directed against its own DNA. Lupus can affect many parts of the body, including the joints, skin, kidneys, heart, lungs, blood vessels, and brain. Although various symptoms may t, some of the most common include extreme e, painful or swollen joints (arthritis), unexplained fever, skin , and kidney problems. Exemplary ms of lupus include painful or swollen joints, unexplained fever, and extreme fatigue. A characteristic red skin rash may appear across the nose and cheeks. Rashes may also occur on the face and ears, upper arms, shoulders, chest, and hands. Other symptoms of lupus include chest pain, hair loss, anemia, mouth ulcers, and pale or purple fingers and toes from cold and stress. Some people also experience headaches, dizziness, sion, confusion, or seizures. Positive factors for SLE diagnosis include circulating anti—nuclear antibodies, anti— DNA antibodies, and anti—Sm antibodies. An FcRn—binding antibody can be useful in treating, preventing, or alleviating SLE or one or more ms of SLE. Lupus, as used herein es cutaneous lupus and lupus nephritits.

Immune Thromocytopenia (ITP) ITP is a disease of increased peripheral platelet destruction, where ts develop antibodies that bind to specific platelet membrane proteins. The anti—platelet antibodies opsonize the platelets, g to destruction by macrophages. Attempts to treat ITP have lly involved suppressing the immune system, which causes an increase in platelet levels. An FcRn—binding antibody can be useful in treating, ting, or alleviating ITP, or one or more symptoms thereof.

Ankylosing Spondylitis Ankylosing litis is an autoimmune disorder that not only affects the spine, but may also affect the hips, shoulders, and knees as the tendons and nts around the bones and joints become inflamed, resulting in pain and stiffness. Ankylosing spondylitis tends to affect people in late adolescence or early adulthood. An FcRn—binding antibody can be useful in treating, preventing, or alleviating ankylosing spondylitis, or one or more symptoms thereof.

Pemphigus Pemphigus is an autoimmune disorder that affects mucous membranes and the skin.

The disorder is characterized by the generation of ntibodies against desmoglein.

Desmoglein is a protein in the family of cadherins and is involved with the formation of omes, which join cells to one another. Pemphigus can be classified as one of three types: pemphigus vulgaris, the most common form of the disorder, wherein auto—antibodies target desmoglein 3. In pemphigus folicaeus auto—antibodies against desmoglein 1 are generated. The third type, and least common er is paraneoplastic pemphigus, wherein autoantibodies target lakins and which is associated with cancers such as lymphoma.

The disorders are commonly diagnosed by a dermatologist by the appearance of the skin and is conformed by the ion of auto—antibodies against desmoglein. Methods of treatment include the administration of steroids and/or the administration of a CD20 antibody such as RituXimab (Rituxan) Cancer “Cancer” as used herein refers to an uncontrolled growth of cells which interferes with the normal functioning of the bodily organs and systems. Cancers which migrate from their original on and seed vital organs can eventually lead to the death of the subject through the onal deterioration of the affected organs. Carcinomas are malignant cancers that arise from epithelial cells and include adenocarcinoma and squamous cell oma. Sarcomas are cancer of the connective or supportive tissue and include arcoma, chondrosarcoma and gastrointestinal stromal tumor. Hematopoietic cancers, such as leukemia, are able to outcompete the normal hematopoietic compartments in a subject, thereby leading to hematopoietic failure (in the form of anemia, thrombocytopenia and neutropenia) ultimately g death. A person of ry skill in the art can classify a cancer as a sarcoma, oma or poietic cancer.

Cancer, as used herein, includes the following types of cancer, breast cancer, biliary tract cancer; bladder cancer; brain cancer including astomas and medulloblastomas; cervical cancer; choriocarcinoma; colon cancer; endometrial cancer; esophageal cancer; gastric cancer; hematological neoplasms including acute lymphocytic and myelogenous leukemia; T—cell acute lymphoblastic ia/lymphoma; hairy cell leukemia; chromic myelogenous leukemia, multiple myeloma; AIDS—associated leukemias and adult T—cell leukemia lymphoma; intraepithelial neoplasms including Bowen's disease and Paget's disease; liver cancer; lung cancer; lymphomas ing n's disease and lymphocytic lymphomas; neuroblastomas; oral cancer including squamous cell carcinoma; ovarian cancer including those arising from epithelial cells, stromal cells, germ cells and mesenchymal cells; pancreatic cancer; prostate cancer; rectal cancer; sarcomas including leiomyosarcoma, rhabdomyosarcoma, rcoma, fibrosarcoma, and osteosarcoma; skin cancer including melanoma, Kaposi’s sarcoma, basocellular cancer, and squamous cell cancer; testicular cancer including germinal tumors such as seminoma, non—seminoma (teratomas, choriocarcinomas), stromal tumors, and germ cell tumors; thyroid cancer ing thyroid adenocarcinoma and medullar carcinoma; and renal cancer including arcinoma and Wilms tumor. Other cancers Will be known to one of ordinary skill in the art.

Treatment ofFetuses FcRn mediates the transport of maternal IgG across epithelial cell rs to fetus.

The antibodies described herein can be used to deliver macromolecular drugs, e.g. antibiotics, and/or small molecules to fetuses in utero. The fetus may be suffering from a condition or disorder (e.g. an enteric infection or metabolic disorder) that requires treatment.

The drug or molecule for treating the condition or disorder can be conjugated to a FcRn binding antibody and administered to a nt woman who has an in utero fetus that is in need of treatment. The conjugated FcRn—binding antibody binds to FcRn and is thereby transported to the fetus via the placenta. The fetus receives the drug or molecule treatment.

Immunadsorption In some ments, the invention provides methods for the removal of an unwanted therapeutic antibody from an dual. In some embodiments, the unwanted therapeutic antibody is an IgG antibody. In some embodiments the unwanted therapeutic antibody is an anti—VLA4 antibody such as Natalizumab (Tysabri, Biogen Idec/ Elan), efalizumab (Raptiva, Genentech), bevacizumab (Avastin, Genentech) and PC fusion proteins such as etanercept (Enbrel, Amgen/Wyeth). Natalizumab onal antibody y has been associated with Progressive Multifocal Leukoencephalopathy (PML). Depletion of the therapeutic antibody from the bloodstream and/or the rest of the body may alter the progression of PML.

In some embodiments, the ent methods presented herein may be combined with methods to remove or partially remove therapeutic antibodies from the bloodstream of a subject. In some embodiments, the anti—FcRn antibodies ted herein may be combined with a capture protein that can bind a therapeutic antibody, the combinations resulting in an increased clearance of the therapeutic antibody from the bloodstream. In some embodiments, the method of l or partial removal of the therapeutic antibody from the tream of a subject is plasma exchange (PLEX). In some embodiments, the anti—FcRn antibodies can be administered to a subject undergoing plasma exchange. In some embodiments, the anti— FcRn antibodies can be used as an immunoadsorbant for FcRn in the plasma exchange process.

In plasma exchange (also called apheresis or plasmapheresis) blood is taken from the body and plasma containing an unwanted agent, such as cholesterol or a therapeutic antibody, is removed from the blood by a cell separator. Blood can be d from the body in batches or it can be removed in a continuous flow mode, with the latter allowing for the reintroduction of the processed blood into the body. The d plasma comprising the unwanted agent can be discarded and the t can receive donor plasma or saline with added proteins in return. In some embodiments, le rounds of plasma exchange may be 2012/040409 needed to remove the unwanted agent from the blood or to lower the level of the unwanted agent in the blood to an acceptable level. In some embodiments the blood is “filtered” and the ed agent removed, before returning the blood to the patient. Methods of plasma exchange are known in the art and are described, for example, in US 6,960,178.

Plasma exchange has been shown to reduce therapeutic antibody levels in the blood of a subject and the restoration of homeostasis (See e.g., Khatri et al; 2009; Neurology 72:402— 409).

An IgG based therapeutic antibody (such as natalizumab) can be d from blood, plasma or serum by contacting the blood with the capture protein Staphylococcal protein A, which will bind the Fc region of IgG and remove the IgG antibody from the bloodstream.

Other capture proteins can be used for ent isotype dies. In some embodiments, the anti—FcRn antibodies can be used as a capture protein in the plasma exchange process, resulting in the removal of FcRn from the tream, thereby increasing the amount of “free” therapeutic antibody. The resulting “free” therapeutic antibody will have a shorter half—life than antibody present prior to treatment and/or can be removed from the blood more readily with a ent capture protein (such as protein A). In some embodiments, the anti— FcRn dies are administered to a patient during or before plasma exchange. In some embodiments, the cRn antibodies can be immobilized and used in a column, resulting in the binding of FcRn. In some embodiments, the blood of a patient that ns a therapeutic dy is contacted both with immobilized anti—FcRn antibody and immobilized protein A.

In some embodiments the anti—FcRn antibodies presented herein can be used in “rescue” therapy for therapeutic antibodies that have been administered and have shown an adverse effect. In some embodiments, an anti—FcRn antibody can be used as an alternative for plasma exchange. The administration of an anti—FcRn can accomplish therapeutic antibody depletion without the risks associated with plasmapheresis and plasma exchange such as vascular access, citrate therapy and donor plasma sourcing.

Human leukocyte antigens Human leukocyte antigens (HLA) present peptides and antigens on the e of the cell, which are subsequently recognized by T—cells, which in their turn can activate B—cells.

The panel of HLA genes available is unique for each person. Any cell displaying an HLA that is “non—self” will result in the induction of an immune response. In general, the more ent the “non—self” HLA from the self HLA, the stronger the immune response. For instance, in the case of organ transplants, subjects with similar HLA genes are red to minimize the immune response. Donor—specific HLA antibodies have been found to be associated with graft e in kidney, heart, lung and liver transplantation.

In some embodiments, the invention provides s for the decreasing the level of “non—self” HLA antibodies in an individual. Decreasing the level of “non—self” HLA antibodies can result in the suppression of an immune response, e.g., during organ transplantation. In some embodiments a person that will be undergoing organ transplation is administered an cRn antibody. In some embodiments a person that is undergoing organ transplation is administered an anti—FcRn antibody. In some embodiments a person that has received an organ transplation is administered an anti—FcRn dy. Assays for measuring the levels of HLA antibodies are well—known in the art. stic Uses Antibodies that bind to FcRn and identified by the method described herein and/or detailed herein have in vitro and in vivo diagnostic utilities.

In one aspect, the disclosure es a diagnostic method for detecting the presence of an FcRn, in vitro or in vivo (e.g., in vivo imaging in a subject). The method can include localizing FcRn to a subcellular location, 6.57., the endosome. The method can include: (i) contacting a sample with FcRn—binding antibody; and (ii) detecting formation of a x between the FcRn—binding antibody and the sample. The method can also include contacting a reference sample (e.g., a control sample) with the antibody, and determining the extent of formation of the complex between the antibody and the sample relative to the same for the reference sample. A change, 6.57., a statistically significant change, in the formation of the complex in the sample or subject relative to the control sample or subject can be indicative of the presence of FcRn in the . r ary method includes: (i) administering the FcRn—binding antibody to a subject; and (iii) detecting formation of a complex between the FcRn—binding antibody and the subject. The detecting can include determining location or time of formation of the complex.

The FcRn—binding antibody can be directly or indirectly labeled with a detectable substance to facilitate detection of the bound or unbound antibody. Suitable detectable substances include various s, etic groups, fluorescent materials, luminescent materials and radioactive materials.

Complex formation between the FcRn—binding dy and FcRn can be ed by measuring or visualizing either the antibody bound to the FcRn or unbound dy.

Conventional detection assays can be used, e.g., an enzyme—linked immunosorbent assays (ELISA), a radioimmunoassay (RIA) or tissue immunohistochemistry. Further to labeling the FcRn—binding antibody, the ce of FcRn can be assayed in a sample by a competition immunoassay utilizing standards d with a detectable substance and an unlabeled FcRn—binding antibody. In one example of this assay, the biological sample, the d standards, and the FcRn—binding antibody are combined and the amount of labeled standard bound to the unlabeled antibody is determined. The amount of FcRn in the sample is inversely proportional to the amount of labeled standard bound to the FcRn—binding antibody.

Fluorophore and chromophore labeled antibodies can be prepared. Because antibodies and other proteins absorb light having wavelengths up to about 310 nm, the fluorescent moieties should be selected to have substantial absorption at wavelengths above 310 nm and preferably above 400 nm. A y of suitable fluorescers and chromophores are described by Stryer,l968, Science 162:526 and Brand, L. et al.,l972, Annu. Rev.

Biochem. 4l:843 868. The antibodies can be labeled with cent chromophore groups by conventional procedures such as those disclosed in US. Patent Nos. 475, 4,289,747, and 4,376,110. One group of fluorescers having a number of the desirable properties described above is the xanthene dyes, which include the fluoresceins and rhodamines.

Another group of fluorescent compounds are the naphthylamines. Once labeled with a fluorophore or phore, the antibody can be used to detect the presence or localization of the FcRn in a sample, e.g., using fluorescent microscopy (such as confocal or olution microscopy).

Histological Analysis. Immunohistochemistry can be performed using the antibodies described herein. For example, the antibody can be sized with a label (such as a purification or epitope tag), or can be detectably labeled, e. g., by conjugating a label or label— binding group. For example, a or can be attached to the antibody. The antibody is then contacted to a histological preparation, e. g., a fixed section of tissue that is on a microscope slide. After an incubation for binding, the preparation is washed to remove unbound dy. The preparation is then analyzed, e. 57., using microscopy, to identify if the dy bound to the preparation.

Of course, the antibody can be unlabeled at the time of binding. After binding and washing, the antibody is labeled in order to render it able.

Protein . The FcRn—binding antibody can also be immobilized on a protein array. The protein array can be used as a stic tool, e.g., to screen medical samples (such as isolated cells, blood, sera, biopsies, and the like). Of course, the n array can also include other ligands, e. g. that bind to FcRn or to other target molecules. s of producing polypeptide arrays are described, e.g., in De Wildt et al., 2000, Nat. Biotechnol. -994; Lueking et al., 1999, Anal. Biochem. 3—1 l 1; Ge, 2000, Nucleic Acids Res. 28, e3, I—VII; MacBeath and Schreiber, 2000, Science 289:1760—1763; WO 01/40803 and WO 99/51773Al. Polypeptides for the array can be spotted at high speed, e.g., using commercially available robotic apparati, e. g., from Genetic MicroSystems or BioRobotics. The array substrate can be, for example, nitrocellulose, plastic, glass, e.g., surface—modified glass. The array can also e a porous matrix, e. 57., acrylamide, agarose, or another polymer.

For example, the array can be an array of antibodies, e.g., as bed in De Wildt, supra. Cells that produce the antibodies can be grown on a filter in an arrayed format.

Antibody production is induced, and the expressed polypeptides are immobilized to the filter at the location of the cell. An dy array can be contacted with a labeled target to determine the extent of binding of the target to each immobilized antibody. Information about the extent of binding at each address of the array can be stored as a profile, e.g., in a computer database. The antibody array can be produced in replicates and used to compare binding profiles, e.g., of a target and a non—target.

FACS (Fluorescence Activated Cell Sorting). The FcRn-binding antibody can be used to label cells, e. 57., cells in a sample (e. g., a patient sample). The antibody is also attached (or able) to a fluorescent compound. The cells can then be sorted using fluorescence activated cell sorter (e. 57., using a sorter available from Becton Dickinson Immunocytometry Systems, San Jose CA; see also US. Patent Nos. 5,627,037; 5,030,002; and 5,137,809). As cells pass through the sorter, a laser beam excites the fluorescent compound while a detector counts cells that pass through and ines whether a fluorescent compound is attached to the cell by detecting fluorescence. The amount of label bound to each cell can be quantified and analyzed to terize the sample.

The sorter can also deflect the cell and separate cells bound by the antibody from those cells not bound by the antibody. The separated cells can be cultured and/or characterized.

In vivo Imaging. Also ed is a method for detecting the presence of a FcRn— expressing tissues in vivo. The method includes (i) administering to a subject (e.g., a patient having an autoimmune disorder) an anti—FcRn antibody, conjugated to a able marker; (ii) exposing the subject to a means for detecting said detectable marker to the FcRn— expressing tissues or cells. For e, the subject is imaged, e. g., by NMR or other tomographic means.

Examples of labels useful for diagnostic imaging include radiolabels such as 131I9 111 123 3 In, 1,99mTc, 32 125 14 188 P, I, H, C, and Rh, fluorescent labels such as fluoresce1n and- rhodamine, nuclear ic resonance active labels, positron emitting isotopes detectable by a positron emission tomography (“PET”) scanner, chemiluminescers such as luciferin, and enzymatic s such as peroxidase or atase. Short range radiation emitters, such as isotopes detectable by short range detector probes can also be employed. The antibody can be d with such reagents using known techniques. For example, see Wensel and Meares, 1983, Radioimmnnoimaging and Radioimmanotlierapy, Elsevier, New York for techniques relating to the radiolabeling of antibodies and D. Colcher et al., 1986, Meth.

Enzymol. 121: 802 816.

A radiolabeled antibody can also be used for in vitro diagnostic tests. The specific ty of a isotopically—labeled antibody s upon the half life, the isotopic purity of the radioactive label, and how the label is incorporated into the antibody.

Procedures for labeling polypeptides with the radioactive isotopes (such as 14C, 3H, 358, 125I, 32P, 131I) are generally known. For example, tritium ng procedures are described in US. Patent No. 4,302,438. Iodinating, m labeling, and 358 labeling procedures, e.g., as adapted for murine monoclonal antibodies, are described, e.g., by Goding, J .W. (Monoclonal antibodies .' principles and practice .' production and application of monoclonal antibodies in cell biology, biochemistry, and immunology 2nd ed. London ; Orlando : Academic Press, 1986. pp 124 126) and the references cited therein. Other procedures for iodinating ptides, such as antibodies, are described by Hunter and Greenwood, 1962, Nature 144:945, David et al., 1974, Biochemistry 13:1014 1021, and US.

Patent Nos. 3,867,517 and 4,376,110. Radiolabeling elements which are useful in imaging - 123 131 111 include I, I, In, and 99mTc, for example. Procedures for iod1nat1ng antibodies are- - - - - described by Greenwood, F. et al., 1963, Biochem. J. 89:114 123; Marchalonis, J., 1969, Biochem. J. 113:299 305; and Morrison, M. et al., 1971, Immanochemistry 289 297.

Procedures for 99mTc labeling are described by Rhodes, B. et al. in Burchiel, S. et al. (eds.), Tumor Imaging: The Radioimmnnochemical ion of Cancer, New York: Masson 111 123 (1982) and the references cited therein. Procedures suitable for In ng antibodies are described by Hnatowich, D]. et al., 1983, J. Immunol. s, 65:147 157, ich, D. et al., 1984, J. Applied Radiation, 35:554 557, and Buckley, R. G. et al., 1984, F.E.B.S. 166:202 204.

In the case of a radiolabeled antibody, the antibody is administered to the patient, is localized to cells bearing the antigen with which the antibody reacts, and is detected or “imaged” in vivo using known ques such as radionuclear scanning using e.g., a gamma camera or emission tomography. See e. 57., AR. Bradwell et al., “Developments in Antibody Imaging”, Monoclonal Antibodies for Cancer ion and Therapy, R.W. Baldwin et al., , pp 65 85 (Academic Press 1985). Alternatively, a positron emission transaxial tomography scanner, such as designated Pet VI located at Brookhaven National Laboratory, can be used where the radiolabel emits ons (e.g., 11C, 18F, 15O, and 13N).

MRI Contrast Agents. Magnetic Resonance Imaging (MRI) uses NMR to visualize internal features of living subject, and is useful for prognosis, diagnosis, treatment, and surgery. MRI can be used without radioactive tracer compounds for s benefit. Some MRI techniques are summarized in EP—A—0 502 814. Generally, the differences related to tion time constants T1 and T2 of water protons in different environments is used to te an image. r, these differences can be insufficient to provide sharp high resolution images.

The differences in these relaxation time constants can be enhanced by contrast agents.

Examples of such contrast agents include a number of magnetic agents paramagnetic agents (which primarily alter T1) and ferromagnetic or superparamagnetic (which ily alter T2 response). Chelates (e.g., EDTA, DTPA and NTA chelates) can be used to attach (and reduce ty) of some paramagnetic substances (e.g., . Fe”, Mn”, Gd+3). Other agents can 2012/040409 be in the form of les, e.g., less than 10 mm to about 10 nM in diameter). Particles can have ferromagnetic, antiferromagnetic, or superparamagnetic properties. Particles can include, e. g., magnetite (Fe3O4), y—Fe203, ferrites, and other magnetic mineral compounds of transition elements. Magnetic particles may include: one or more magnetic crystals with and without nonmagnetic material. The nonmagnetic al can include synthetic or natural polymers (such as sepharose, dextran, dextrin, starch and the like.

The FcRn—binding antibody can also be d with an indicating group containing of the NMR active 19F atom, or a plurality of such atoms inasmuch as (i) substantially all of naturally abundant fluorine atoms are the 19F e and, thus, substantially all fluorine containing compounds are NMR ; (ii) many chemically active polyfluorinated compounds such as trifluoracetic anhydride are commercially available at relatively low cost; and (iii) many fluorinated compounds have been found medically acceptable for use in humans such as the orinated polyethers utilized to carry oxygen as hemoglobin replacements. After permitting such time for incubation, a whole body MRI is carried out using an apparatus such as one of those described by Pykett, 1982, Sci. Am. 246:78 88 to locate and image tissues expressing FcRn.

The disclosure also features kits comprising an antibody that binds to FcRn and instructions for diagnostic use, e.g., the use of the FcRn—binding antibody or antigen—binding fragment thereof, to detect FcRn, in vitro, e.g., in a sample, e.g., a biopsy or cells from a patient having an autoimmune disorder, or in vivo, e.g., by imaging a subject. The kit can further contain a least one additional reagent, such as a label or additional diagnostic agent.

For in viva use the antibody can be ated as a pharmaceutical composition.

The present ion is further illustrated by the ing Examples, which in no way should be construed as further limiting. The entire contents of all of the references (including literature references, issued patents, published patent applications, and co—pending patent applications) cited throughout this application are hereby sly incorporated by reference, in particular for the teaching that is referenced hereinabove.

EXAMPLE 1: DX2504 and Cysteine s Thereof The light chain of the DX—2504 anti—FcRn antibody has an unpaired cysteine in the first on of CDR3. This cysteine is adjacent to the cysteine in the FR3 that pairs with the cysteine in the FRl of light chains. We constructed two mutants that replace the cysteine in the CDR3 with either a serine or an alanine. (See below and see also Figure 9). l) 532A—X53—C02: cys to ser mutant 2) 532A—X54—B03: cys to ala mutant Sequence Alignment of the Light Chains of DX—2504 (SEQ ID NO:8), 532A-X53—C02 (SEQ ID , and 532A-X54-B03 (SEQ ID NO:ll) FRl—L CDRl—L FR2—L CDR2—L DX—2504: QSAJTQPASVSGSPGQSITISC TGTGSDVGSYNAVS WYQQHPGKAPKJMIY GDSQRPS 532A—X53—C02 QSAJTQPASVSGSPGQSITISC TGTGSDVGSYNJVS WYQQHPGKAPKAMIY GDSQRPS 532A—X54—303 QSAJTQPASVSGSPGQSITISC TGTGSDVGSYNJVS WYQQHPGKAPKAMIY GDSQRPS FR3—L CDR3—L FR4—L DX—2504: SGSKSGNTAS.TISG.QAfiDfiADYYC ESYAGSGIYV FGTGTKVTVJ 532A—X53—C02: GVSBRFSGSKSGNTAS.TISG.QAfiDfiADYYC ESYAGSGIYV FGTGTKVTVJ 532A—X54—303: GVSBRFSGSKSGNTAS.TISG.QAfiDfiADYYC GIYV VTVJ Size exclusion chromatography (SEC) analysis 504, 532A-X53-C02 and 4- 303 Antibody purity was assessed by injecting 50 ug protein over a Tosoh G3000 SWXL column equilibrated in 0.2M Sodium Phosphate, pH: 6.9 on a Waters 2695 HPLC system with UV detection. Integrated peak areas were expressed as % r (i. e. intact antibody), % high molecular weight aggregates (%HMW), and % low molecular weight species (%LMW) in Table I. (See also Figure I).

Table 1. Summary of SEC Results % HMWA % LMW SDS-PAGE analysis 0fDX-2504, 532A-X53-C02 and 532-X54-BO3 Antibodies were treated with 50 mM N—ethylmaleimide followed by SDS—PAGE sample buffer and heated for 10 minutes at 72°C to block free thiol that may lead to gel artifacts. Antibody (4 ug) was loaded onto a 4—12 % gradient NuPAGE gel and stained with Simply Blue Safe Stain, prior to densitometry analysis using a UVP system (Table 2). (See also Figure 2) Table 2. Summary of Densitometry Analyses Densitometry Analysis on Non-reduced mAb Samples Band I.D. DX-2504 532A-X54-B03 532A-X53-C02 2H/2L (Monomer) 81.6% 92.8% 92.4% 2H/1L 13.8% 6.8% 0.9% Temperature stability 0fDX-2504, 532A-X53-C02 and 532-X54-BO3 DX—2504, 532A—X53—C02 and 532—X54—B03_samples were incubated at 37°C for 1 month. Samples were taken at different time points for analysis using ical SEC. ature stability of DX—2504 and ne mutants is presented based on the change in % monomer. (See Figure 3). pH Stability 0fDX-2504, 532A-X53-C02 and 532-X54-BO3 4, 532A—X53—C02 and 532—X54—B03 samples were incubated in different pH conditions at room temperature for 1 month. Samples were taken at different time points for analysis using analytical SEC. pH stability of DX—2504 and cysteine s is presented based on the change in % monomer. (See Figure 4).

Stability 0fDX-2504, 532A-X53-C02 and 532-X54-BO3 atpH 8.3 Stability was assessed using SEC as bed in the paragraph above Table 1. The SEC is of the antibodies at pH 8.3 is shown since it illustrates the improved stability of the cysteine mutants over DX—2504 at tested pH condition. (See Figure 5).

Thiol titration with DTNB The presence of free cysteine thiols in the purified antibody ons was ed by reacting 10 uM antibody with 10 mM DTNB (Ellman’s reagent, or ithio—bis (2— nitrobenzoic acid)) in the presence or absence of the denaturation reagent 6 M guanidine hydrochloride for 0.5 hours at 37°C before reading the absorbance of the reaction at 412 nm (8 = 14,100 M'lcm'l). The concentration of thiol was diVided by the concentration of antibody to obtain the mol thiol/mol of mAb. (See Table 3 below).

Table 3. Summary of Thiol Titration Data DTNB Assay - 10 uM mAb Free Thiol/mol mAb Free Thiol/mol mAb Sample ID Not Denatured Denatured DX-2504 0.62 532A-X54-B03 0.05 0.31 532A-X53-C02 0.05 0.25 ity ofDX-2504, 532A-X53-C02 and 532-X54-BO3 towards chemical denaturation.

Protein stability of DX—2504 and ne mutants was ed by ring intrinsic cence as a on of chemical rant guanidine hydrochloride (GuHCl) tration. 1mg/ml of each antibody product were prepared with different tration of GuHCl 1 to 8M. Fluorescence was measured and the intensity ratio of 360/330 as a function of GuHCl concentration is plotted. Cysteine mutants show better stability for structural conformation changes against denaturant reagent. (See Figure 6).

Surface plasmon resonance (SPR or Biacore) kinetic analysis ofthe interaction ofhFcRn with immobilized DX-2504, 532A-X53-C02 and 532-X54-BO3.

SPR measurements were performed using a Biacore 3000. DX—2504, 532A—X53—C02 and 4—B03 were immobilized by amine coupling on CM5 sensor chips at immobilization densities of ~220 RU. To measure the kinetic parameters of DX—2504 interaction with FcRn analyte, twofold serial dilutions prepared from 100 nM of FcRn were injected in duplicate for 5 min at 50 l/min with a 15 minute dissociation phase. The sensor chip surface was regenerated with a 30 sec pulse of 10 mM glycine pH 1.5 at a flow rate of 75 l/min followed by a 15 second pulse of buffer. Measurements were performed at 25°C using HBS—P as the running buffer. The reference flow cell was activated and blocked in a mock amine coupling reaction. The data was fit to a 1:1 binding model using Biaevalution V.4.1 software. (See Table 4, Figure 7 and Figure 8). 2012/040409 Table 4. Summary of SPR Results pH 6-0 532A—X54—B03 1.1 x 10 2.2 x 10' pH 7.5 53—C02 1.9 x 10 3.2 x 10‘ DX-2504 lot 040709 1.5 x 10 2.8 x 10' EXAMPLE 2: on Mutant of DX—2504 The heavy chain of the DX—2504 anti—FcRn antibody contains a lysine at the last position (C—terminus) in the heavy chain. Mutant DX—2507 (light chain SEQ ID NO: 18, heavy chain SEQ ID NO:19) contains the same light chain as that of DX—2504 and a mutated heavy chain, which was constructed by deleting the C—terminal lysine residue in the heavy chain of DX—2504. A sequence alignment n the C—terminal fragment of DX—2504 heavy chain (SEQ ID NO:20) and that of DX—2507 heavy chain (SEQ ID NO:21) is shown below: DX—2504: SDGSFF .YSK .TVDKSRWQQGNVFSCSVMH'QA .HNHYTQKS .S -SPGK DX—2507: SDGSFF .YSK .TVDKSRWQQGNVFSCSVMH'QA .HNHYTQKS -S -SPG Pharmacologic profile and Toxicokinetic profile ofDX-2504 and DX-2507 in Cynomolgus Monkeys SiX naive female cynomolgus monkeys were assigned to 2 dose groups each consisting of 3 animals. Table 5 provides a summary of the study design. All animals were dosed 20mg/kg of the test antibody via subcutaneous (SC) injection once on Study Day 0 and Study Day 7. Group 1 animals were administered DX—2504 and Group 2 animals were administered 7. Blood was collected from all animals at the ing time points: Day 0 (prior to dosing and 2 and 12 hours post—dose), Days 1, 2, ,3 ,4 ,5 ,6, Day 7 (prior to dosing and 2 and 12 hours ose), Days 8, 9, 10, 11, 12, 13, 14, 17, 21, 24, 28, 31 and 35.

Serum samples for toxicokinetics of DX—2504 and DX—2507 were analyzed using a qualified ELISA method (DRD—910—029). Total cynomolgus monkey IgG levels were analyzed using a qualified ELISA method (DRD_910—033).

Table 5: Study Design Group # of Test Ab Dose level Route Dose Dose Animals (mg/kg/dose) Concentration volume (m_ mL) (mL/k_) DX—2504 serum concentrations were detected from 2 hours post—dose on Day 0 through Day 11 in 2 animals and Day 13 in one animal. DX—2507 serum concentrations were ed from 2 hours post—dose on Day 0 through Day 11, Day 12, and Day 17 in individual animals. The results thus obtained show that the serum concentrations of DX—2507 were much higher than those of DX—2504 in the test animals, indicating that DX—2507 was more stable in Vivo than DX—2504. Figure 13.

Cynomolgus monkey IgG levels were reduced following administration of both DX— 2504 and DX—2507 (Figure 14). Following administration of the Day 0 dose, mean total IgG levels were reduced to 42% and 33% of pre—dose baseline levelsin the DX—2504 and DX— 2507 dose groups, respectively. Prior to the Day 7 dose, mean total IgG levels increased to 45% and 37% of predose baseline levels in the same treatment groups. Following stration of the Day 7 dose, mean total IgG levels were reduced to 42% of predose baseline values in the DX—2504 group and to 30% of predose baseline values in the 7 group. Total IgG levels d to predose baseline values on Day 13 in the DX—2504—treated animals and on Day 21 in the DX—2507—treated animals.

The mean toxicokinetic parameters for DX—2504 and 7 are summarized in Table 6.

Table 6: Mean (SD) Toxicokinetic parameters Cmax t CL/F VZ/F 11/2 (d) (ug/mL) (d*ug/mL) (mL/d/Kg) ) —-70.8 341.0 879.1 1.9 (25.8) (32.2) (204.5) (407.0) (0.2) DX_2504 47.5 492.3 312.4 0.4 (15.7) (20.0) (264.0) (252.0) (0.1) n-135.6 152.0 74.1 0.3 (19.7) (29.4) (31.8) (35.0) (0.1) DX'2507 120.3 166.3 73.6 0.3 (4.7) (3.2) (4.3) (24.8) (0.1) >"Serum concentration es were corrected for e (Day 7) baseline concentrations The toxicokinetic parameters for both DX-2504 and DX-2507 were substantially consistent on days 0 and 7. The overall exposure of DX-2507 was greater than that observed for DX-2504. The mean maximum concentration (Cmax) and plasma/serum concentration-time curve (AUCiast) values for DX-2507 on either Day 0 or Day 7 were between 2 to 3-fold greater than the corresponding values calculated for DX-2504. In addition, the corresponding mean apparent clearance (CL/F) and distribution volume (Vz/F) values for DX-2504 were between 2 to 12-fold greater than DX-2507.

Equivalents The foregoing written specification is considered to be sufficient to enable one skilled in the art to practice the invention. The present invention is not to be limited in scope by examples provided, since the examples are intended as a single illustration of one aspect of the invention and other functionally equivalent embodiments are within the scope of the invention. s modifications of the invention in addition to those shown and described herein will become apparent to those d in the art from the foregoing ption and fall within the scope of the appended claims. The advantages and objects of the invention are not necessarily encompassed by each ment of the ion.

The contents of all nces, s and published patent applications cited throughout this ation are incorporated herein by reference in their entirety, particularly for the use or subject matter referenced .

Throughout the specification and claims, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of rs but not the exclusion of any other integer or group of integers.

Claims (18)

What is claimed 1. is:

1. An isolated antibody comprising a light chain variable region (VL) and a heavy chain variable region (VH), wherein the antibody binds to human FcRn; and wherein the VL comprises: 5 (i) a VL CDRl comprising the amino acid sequence TGTGSDVGSYNLVS (SEQ ID NO: 14), (ii) a VL CDR2 comprising the amino acid sequence S (SEQ ID NO: 15), and (iii)a VL CDR3 comprising the amino acid sequence SSYAGSGIYV (SEQ 10 ID NO: 12) or ASYAGSIYV (SEQ ID NO: 13), and the VH comprises: (i) a VH CDR1 comprising the amino acid sequence EYAMG (SEQ ID NO: 22); (ii) a VH CDR2 sing the amino acid sequence 15 SIGSSGGQTKYADSVKG (SEQ ID NO: 23); and (iii) a VH CDR3 comprising the amino acid sequence LAIGDSY (SEQ ID NO: 24).

2. The isolated antibody of claim 1, wherein the VL of the isolated antibody comprises the amino acid sequence of SEQ ID NO: 10 or SEQ ID NO: 11. 20

3. The isolated antibody of claim 1, wherein the VH of the isolated antibody comprises the amino acid ce of SEQ ID NO:9.

4. An ed antibody comprising a light chain variable region (VL), a heavy chain that comprises a heavy chain le region (VH) and a heavy chain constant region, wherein the antibody binds to human FcRn; and wherein the VL 25 comprises: (i) a VL CDRl comprising the amino acid sequence TGTGSDVGSYNLVS (SEQ ID NO: 14), (ii) a VL CDR2 comprising the amino acid sequence GDSQRPS (SEQ ID NO: 15), and (iii)a VL CDR3 sing the amino acid sequence CSYAGSGIYV (SEQ ID NO: 25), SSYAGSGIYV (SEQ ID NO: 12) or ASYAGSIYV 5 (SEQ ID NO: 13), and the VH comprises: (i) a VH CDR1 comprising the amino acid sequence EYAMG (SEQ ID NO: 22) (ii) a VH CDR2 comprising the amino acid sequence comprising 10 the amino acid sequence SIGSSGGQTKYADSVKG (SEQ ID NO: 23); and (iii) VH CDR3 sing the amino acid sequence LAIGDSY (SEQ ID NO: 24); and the CH has a deletion corresponding to the C-terminal lysine e at the 15 last position of SEQ ID NO: 17.

5. The isolated antibody of claim 4, wherein the VL of the isolated antibody comprises the amino acid sequence of SEQ ID NO: 8, SEQ ID NO: 10 or SEQ ID NO: 11.

6. The antibody of any one of claims 1-4, wherein the antibody binds 20 human FcRn with a dissociation constant (KD) of less than 10 nM.

7. The dy of any one of claims 1-4, wherein the antibody is a human or humanized antibody or is non-immunogenic in a human.

8. The antibody of any one of claims 1-4, wherein the antibody is chimeric. 25

9. The antibody of any one of claims 1-4, wherein the antibody is ed from the group consisting of Fab, F(ab)'2, Fv, and scFv.

10. A pharmaceutical ition comprising the dy of any one of claims 1-4 and a pharmaceutically acceptable carrier.

11. An isolated nucleic acid comprising a nucleotide sequence that encodes the dy of any one of claims 1-4. 5

12. A vector comprising the nucleic acid of claim 11.

13. A host cell comprising the vector of claim 12, wherein the host cell is cultured in vitro.

14. An in vitro method of detecting an FcRn in a , the method comprising: 10 ting the sample with the antibody of any one of claims 1-4, and detecting an interaction between the antibody and the FcRn if present.

15. The antibody of any one of claims 1-4, for use in detecting an FcRn in a subject.

16. Use of the antibody of any one of claims 1-4 in manufacturing a 15 medicament for modulating an FcRn activity.

17. Use of the antibody of any one of claims 1-4 in manufacturing a medicament for treating an autoimmune disorder in a subject.

18. Use of the antibody of any one of claims 1-4 in the manufacture of a medicament for modulating the half life/levels of circulating IgG in a subject.