WO2015036394A1

WO2015036394A1 - Antibodies against pd-1 and uses thereof

Info

Publication number: WO2015036394A1
Application number: PCT/EP2014/069170
Authority: WO
Inventors: Andrew G Buchanan; Stewart Ross; Matthieu Chodorge
Original assignee: Medimmune Limited
Priority date: 2013-09-10
Filing date: 2014-09-09
Publication date: 2015-03-19
Also published as: US20160222113A1; US10077305B2

Abstract

The present invention provides antibodies and antigen-binding fragments that specifically bind PD-1 (Programmed Death 1), thereby modulating immune responses in general, and those mediated by TcR and CD28, in particular. The disclosed compositions and methods may be used for example, in treating autoimmune diseases, inflammatory disorders, allergies, transplant rejection, cancer, and other immune system disorders.

Description

ANTIBODIES AGAINST PD-1 AND USES THEREOF

BACKGROUND OF THE INVENTION

An adaptive immune response involves activation, selection, and clonal proliferation of two major classes of lymphocytes termed T cells and B cells. After encountering an antigen, T cells proliferate and differentiate into antigen-specific effector cells, while B cells proliferate and differentiate into antibody-secreting cells.

T cell activation is a multi-step process requiring several signaling events between the T cell and an antigen-presenting cell (APC). For T cell activation to occur, two types of signals must be delivered to a resting T cell. The first type is mediated by the antigen-specific T cell receptor (TcR), and confers specificity to the immune response. The second, costimulatory, type regulates the magnitude of the response and is delivered through accessory receptors on the T cell.

A primary costimulatory signal is delivered through the activating CD28 receptor upon engagement of its ligands B7-1 or B7-2. In contrast, engagement of the inhibitory CTLA-4 receptor by the same B7-1 or B7-2 ligands results in attenuation of T cell response. Thus, CTLA- 4 signals antagonize costimulation mediated by CD28. At high antigen concentrations, CD28 costimulation overrides the CTLA-4 inhibitory effect. Temporal regulation of the CD28 and CTLA-4 expression maintains a balance between activating and inhibitory signals and ensures the development of an effective immune response, while safeguarding against the development of autoimmunity.

Molecular homologues of CD28 and CTLA-4 and their B-7 like ligands have been recently identified. ICOS is a CD28-like costimulatory receptor. PD-1 (Programmed Death 1) is an inhibitory receptor and a counterpart of CTLA-4. In one example, binding of PD-L1 with its receptor PD-1 on T cells delivers a signal that inhibits TCR-mediated activation of IL-2 production and T cell proliferation. This disclosure relates to modulation of immune responses mediated by the PD-1 receptor.

PD-1 is a 50-55 kDa type I transmembrane receptor that was originally identified in a T cell line undergoing activation-induced apoptosis. P D-1 is expressed on T cells, B cells, and macrophages. The ligands for PD-1 are the B7 family members PD-L1 (B7-H1) and PD-L2 (B7- DC).

PD-1 is a member of the immunoglobulin (Ig) superfamily that contains a single Ig V- like domain in its extracellular region. The PD-1 cytoplasmic domain contains two tyrosines, with the most membrane-proximal tyrosine (VAYEEL in mouse PD-1) located within an ITIM (immuno-receptor tyrosine-based inhibitory motif). The presence of an ITIM on PD-1 indicates that this molecule functions to attenuate antigen receptor signaling by recruitment of cytoplasmic phosphatases. Human and murine PD-1 proteins share about 60% amino acid identity with conservation of four potential N-glycosylation sites, and residues that define the Ig-V domain. The ITIM in the cytoplasmic region and the ITIM-like motif surrounding the carboxy-terminal tyrosine (TEYATI in human and mouse) are also conserved between human and murine orthologues.

PD-1 is expressed on activated T cells, B cells, and monocytes. Experimental data implicates the interactions of PD-1 with its ligands in downregulation of central and peripheral immune responses. In particular, proliferation in wild-type T cells but not in PD-1 -deficient T cells is inhibited in the presence of PD-L1. Additionally, PD-1 -deficient mice exhibit an autoimmune phenotype. PD-1 deficiency in the C57BL/6 mice results in chronic progressive lupus-like glomerulonephritis and arthritis. In Balb/c mice, PD-1 deficiency leads to severe cardiomyopathy due to the presence of heart-tissue-specific self-reacting antibodies.

In general, a need exists to provide safe and effective therapies for immune disorders such as, for example, autoimmune diseases, inflammatory disorders, allergies, transplant rejection, cancer, immune deficiency, and other immune system-related disorders. Modulation of the immune responses involved in these disorders can be accomplished by manipulation of the PD-1 pathway.

SUMMARY OF THE INVENTION

As described below, the present invention features antibodies that can act as antagonists of PD-1, thereby modulating immune responses regulated by PD-1. The disclosure further provides anti-PD-1 antibodies that comprise novel antigen-binding fragments. In certain embodiments, an isolated antibody or antigen-binding fragment thereof of the invention specifically binds to a PD-1 polypeptide and comprises a VH and/or a VL domain, where the VH and/or VL domain are each identical to or each have at least 90%, 95%, or 98% identity to the VH and VL amino acid sequences of SEQ ID NOs: 7 and 9. In particular embodiments, the isolated antibody or antigen-binding fragment thereof comprises a V_H domain of LOPD180 corresponding to SEQ ID NO: 7 and/or a V_L domain of LOPD180 corresponding to SEQ ID NO: 9.

In further embodiments, the isolated antibody or antigen-binding fragment thereof comprises a V_H domain or an antigen-binding fragment thereof that comprises 3 CDRs of LOPD180; and a V_L domain or an antigen-binding fragment thereof that comprises 3 CDRs of LOPD180. In other embodiments, the isolated antibody or antigen-binding fragment thereof that consists essentially of LOPD180.

In additional embodiments, the isolated antibody or antigen-binding fragment thereof specifically binds an epitope within the extracellular domain of human or mouse PD-1. In other embodiments, the isolated antibody or antigen-binding fragment thereof is an antigen binding fragment Fab, F(ab')₂, Fv, scFv, Fd or dAb.

In certain embodiments, the isolated antibody or antigen-binding fragment thereof specifically binds to the extracellular domain of PD-1 with an affinity constant greater than 10 M^_1. In other embodiments, the isolated antibody or antigen-binding fragment thereof inhibits the binding of PD-L1 or PD-L2 to PD-1 with an IC₅₀ of less than ΙΟηΜ.

In further embodiments, the isolated antibody or antigen-binding fragment thereof is a human antibody or antigen-binding fragment thereof. In other embodiments the antibody is an IgGi or IgG₄. In further embodiments, the antibody is an IgG or IgGi_K.

In particular embodiments, the isolated antibody or antigen-binding fragment thereof of comprises a VH and/or a VL domain where the VH domain comprises HI, H2 and H3 regions, where HI corresponds to amino acids 31-37 of SEQ ID NO: 7, where H2 corresponds to amino acids 52-67 of SEQ ID NO: 7, and where H3 corresponds to amino acids 110-116 of SEQ ID NO: 7 and/or the VL domain comprises LI, L2 and L3 regions, where LI corresponds to amino acids 23-35 of SEQ ID NO: 9, where L2 corresponds to amino acids 51-57 of SEQ ID NO: 9, and where L3 corresponds to amino acids 90-100 of SEQ ID NO: 9. The invention further provides for a pharmaceutical composition comprising the isolated antibody or antigen-binding fragment thereof of the invention The invention also provides for a kit comprising the isolated antibody or antigen-binding fragment thereof of the invention, and directions for the use of the antibody in an immunological assay.

Definitions

Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which this invention belongs. The following references provide one of skill with a general definition of many of the terms used in this invention: Singleton et al., Dictionary of Microbiology and Molecular Biology (2nd ed. 1994); The Cambridge Dictionary of Science and Technology (Walker ed., 1988); The Glossary of Genetics, 5th Ed., R. Rieger et al. (eds.), Springer Verlag (1991); and Hale & Marham, The Harper Collins Dictionary of Biology (1991). As used herein, the following terms have the meanings ascribed to them below, unless specified otherwise.

By "PD-1 polypeptide" is meant a polypeptide or fragment thereof having at least about 85% amino acid identity to NCBI Accession No. NP_005009 and having PD-L1 and/or PD-L2 binding activity.

By "PD-1 nucleic acid molecule" is meant a polynucleotide encoding a PD-1

polypeptide. An exemplary PD-1 nucleic acid molecule sequence is provided at NCBI

Accession No. NM_005018.

By "PD-L1 polypeptide" is meant a polypeptide or fragment thereof having at least about 85% amino acid identity to NCBI Accession No. NP_001254635 and having PD-1 binding activity.

By "PD-L1 nucleic acid molecule" is meant a polynucleotide encoding a PD-L1 polypeptide. An exemplary PD-L1 nucleic acid molecule sequence is provided at NCBI

Accession No. NM_001267706.

By "PD-L2 polypeptide" is meant a polypeptide or fragment thereof having at least about 85% amino acid identity to NCBI Accession No. NP_079515 and having PD-1 binding activity. By "PD-L2 nucleic acid molecule" is meant a polynucleotide encoding a PD-L2 polypeptide. An exemplary PD-L2 nucleic acid molecule sequence is provided at NCBI

Accession No. NM_025239.

Select exemplary sequences delineated herein are described below.

A "biomarker" or "marker" as used herein generally refers to a protein, nucleic acid molecule, clinical indicator, or other analyte that is associated with a disease. In one

embodiment, a marker of a disease is differentially present in a biological sample obtained from a subject having or at risk of developing the disease relative to a reference. A marker is differentially present if the mean or median level of the biomarker present in the sample is statistically different from the level present in a reference. A reference level may be, for example, the level present in a sample obtained from a healthy control subject or the level obtained from the subject at an earlier timepoint, i.e., prior to treatment. Common tests for statistical significance include, among others, t-test, ANOVA, Kruskal-Wallis, Wilcoxon, Mann- Whitney and odds ratio. Biomarkers, alone or in combination, provide measures of relative likelihood that a subject belongs to a phenotypic status of interest. The differential presence of a marker of the invention in a subject sample can be useful in characterizing the subject as having or at risk of developing an immune disorder, for determining the prognosis of the subject, for evaluating therapeutic efficacy, or for selecting a treatment regimen.

"Biological activity" when used herein in the context of a PD-1 or PD-Ll polypeptide refers to a biological function that results from the activity of the native PD-1 and/or PD-Ll polypeptide. A particular PD-1 and/or PD-Ll biological activity includes, for example, negative regulation of immune responses, reduced T cell proliferation, and reduced IFN-γ production, and/or reduced IL-2 production.

By "agent" is meant any small molecule chemical compound, antibody, nucleic acid molecule, or polypeptide, or fragments thereof.

By "alteration" or "change" is meant an increase or decrease. An alteration may be by as little as 1%, 2%, 3%, 4%, 5%, 10%, 20%, 30%, or by 40%, 50%, 60%, or even by as much as 70%, 75%, 80%, 90%, or 100%.

The term "antibody," as used in this disclosure, refers to an immunoglobulin or a fragment or a derivative thereof, and encompasses any polypeptide comprising an antigen- binding site, regardless whether it is produced in vitro or in vivo. The term includes, but is not limited to, polyclonal, monoclonal, monospecific, polyspecific, non-specific, humanized, single- chain, chimeric, synthetic, recombinant, hybrid, mutated, and grafted antibodies. Unless otherwise modified by the term "intact," as in "intact antibodies," for the purposes of this disclosure, the term "antibody" also includes antibody fragments such as Fab, F(ab')₂, Fv, scFv, Fd, dAb, and other antibody fragments that retain antigen-binding function, i.e., the ability to bind PD-1 specifically. Typically, such fragments would comprise an antigen-binding domain.

The terms "antigen-binding domain," "antigen-binding fragment," and "binding fragment" refer to a part of an antibody molecule that comprises amino acids responsible for the specific binding between the antibody and the antigen. In instances, where an antigen is large, the antigen-binding domain may only bind to a part of the antigen. A portion of the antigen molecule that is responsible for specific interactions with the antigen-binding domain is referred to as "epitope" or "antigenic determinant." An antigen-binding domain typically comprises an antibody light chain variable region (V_L) and an antibody heavy chain variable region (V_H), however, it does not necessarily have to comprise both. For example, a so-called Fd antibody fragment consists only of a V_H domain, but still retains some antigen-binding function of the intact antibody.

Binding fragments of an antibody are produced by recombinant DNA techniques, or by enzymatic or chemical cleavage of intact antibodies. Binding fragments include Fab, Fab', F(ab')2, Fv, and single-chain antibodies. An antibody other than a "bispecific" or "bifunctional" antibody is understood to have each of its binding sites identical. Digestion of antibodies with the enzyme, papain, results in two identical antigen-binding fragments, known also as "Fab" fragments, and a "Fc" fragment, having no antigen-binding activity but having the ability to crystallize. Digestion of antibodies with the enzyme, pepsin, results in the a F(ab')2 fragment in which the two arms of the antibody molecule remain linked and comprise two-antigen binding sites. The F(ab')2 fragment has the ability to crosslink antigen. "Fv" when used herein refers to the minimum fragment of an antibody that retains both antigen-recognition and antigen-binding sites. "Fab" when used herein refers to a fragment of an antibody that comprises the constant domain of the light chain and the CHI domain of the heavy chain. The term "mAb" refers to monoclonal antibody. Antibodies of the invention comprise without limitation whole native antibodies, bispecific antibodies; chimeric antibodies; Fab, Fab', single chain V region fragments (scFv), fusion polypeptides, and unconventional antibodies.

By "biologic sample" is meant any tissue, cell, fluid, or other material derived from an organism.

By "capture reagent" is meant a reagent that specifically binds a nucleic acid molecule or polypeptide to select or isolate the nucleic acid molecule or polypeptide.

As used herein, the terms "determining", "assessing", "assaying", "measuring" and "detecting" refer to both quantitative and qualitative determinations, and as such, the term "determining" is used interchangeably herein with "assaying," "measuring," and the like. Where a quantitative determination is intended, the phrase "determining an amount" of an analyte and the like is used. Where a qualitative and/or quantitative determination is intended, the phrase "determining a level" of an analyte or "detecting" an analyte is used.

The term "effective amount" refers to a dosage or amount that is sufficient to reduce the activity of PD-1 to result in amelioration of symptoms in a patient or to achieve a desired biological outcome. Desired biological outcomes include, for example, increased cytolytic activity of T cells, induction of immune tolerance, reduction or increase of the PD-1 activity associated with the negative regulation of T-cell mediated immune response.

The term "isolated" refers to a molecule that is substantially free of other elements present in its natural environment. For instance, an isolated protein is substantially free of cellular material or other proteins from the cell or tissue source from which it is derived. The term "isolated" also refers to preparations where the isolated protein is sufficiently pure to be administered as a pharmaceutical composition, or at least 70-80% (w/w) pure, more preferably, at least 80-90% (w/w) pure, even more preferably, 90-95% pure; and, most preferably, at least 95%, 96%, 97%, 98%, 99%, or 100% (w/w) pure.

The term "subject" or "patient" refers to an animal which is the object of treatment, observation, or experiment. By way of example only, a subject includes, but is not limited to, a mammal, including, but not limited to, a human or a non-human mammal, such as a non-human primate, murine, bovine, equine, canine, ovine, or feline. The term "reduce" or "increase" is meant to alter negatively or positively, respectively. An alteration may be by 5%, 10%, 25%, 30%, 50%, 75%, or even by 100%.

By "reference" is meant a standard of comparison. For example, when describing the level of sequence identity of a polypeptide or nucleic acid molecule, the level of sequence identity may be expressed as a percentage of the amino acid or nucleotides in common with a reference sequence when the sequence of the polypeptide or nucleic acid molecule aligned with a reference sequence. In another example, the PD-1 or PD-L1 polypeptide or polynucleotide level present in a patient sample may be compared to the level of said polypeptide or polynucleotide present in a corresponding healthy cell or tissue. In one embodiment, the standard of comparison is the level of PD-1 or PD-L1 polypeptide or polynucleotide level present in serum of a subject that does not have an immune disorder.

The term "repertoire" refers to a genetically diverse collection of nucleotides derived wholly or partially from sequences that encode expressed immunoglobulins. The sequences are generated by in vivo rearrangement of, e.g., V, D, and J segments for H chains and, e.g., V and J segment for L chains. Alternatively, the sequences may be generated from a cell line by in vitro stimulation, in response to which the rearrangement occurs. Alternatively, part or all of the sequences may be obtained by combining, e.g., unrearranged V segments with D and J segments, by nucleotide synthesis, randomised mutagenesis, and other methods, e.g., as disclosed in U.S. Pat. No. 5,565,332.

Nucleic acid molecules useful in the methods of the invention include any nucleic acid molecule that encodes a polypeptide of the invention or a fragment thereof. Such nucleic acid molecules need not be 100% identical with an endogenous nucleic acid sequence, but will typically exhibit substantial identity. Polynucleotides having "substantial identity" to an endogenous sequence are typically capable of hybridizing with at least one strand of a double- stranded nucleic acid molecule. By "hybridize" is meant pair to form a double-stranded molecule between complementary polynucleotide sequences (e.g., a gene described herein), or portions thereof, under various conditions of stringency. (See, e.g., Wahl, G. M. and S. L. Berger (1987) Methods Enzymol. 152:399; Kimmel, A. R. (1987) Methods Enzymol. 152:507).

For example, stringent salt concentration will ordinarily be less than about 750 mM NaCl and 75 mM trisodium citrate, preferably less than about 500 mM NaCl and 50 mM trisodium citrate, and more preferably less than about 250 mM NaCl and 25 mM trisodium citrate. Low stringency hybridization can be obtained in the absence of organic solvent, e.g. , formamide, while high stringency hybridization can be obtained in the presence of at least about 35% formamide, and more preferably at least about 50% formamide. Stringent temperature conditions will ordinarily include temperatures of at least about 30° C, more preferably of at least about 37° C, and most preferably of at least about 42° C. Varying additional parameters, such as hybridization time, the concentration of detergent, e.g. , sodium dodecyl sulfate (SDS), and the inclusion or exclusion of carrier DNA, are well known to those skilled in the art. Various levels of stringency are accomplished by combining these various conditions as needed. In a preferred: embodiment, hybridization will occur at 30° C in 750 mM NaCl, 75 mM trisodium citrate, and 1% SDS. In a more preferred embodiment, hybridization will occur at 37° C in 500 mM NaCl, 50 mM trisodium citrate, 1% SDS, 35% formamide, and 100 μg ml denatured salmon sperm DNA (ssDNA). In a most preferred embodiment, hybridization will occur at 42° C in 250 mM NaCl, 25 mM trisodium citrate, 1% SDS, 50% formamide, and 200 μ^πιΐ ssDNA. Useful variations on these conditions will be readily apparent to those skilled in the art.

For most applications, washing steps that follow hybridization will also vary in stringency. Wash stringency conditions can be defined by salt concentration and by temperature. As above, wash stringency can be increased by decreasing salt concentration or by increasing temperature. For example, stringent salt concentration for the wash steps will preferably be less than about 30 mM NaCl and 3 mM trisodium citrate, and most preferably less than about 15 mM NaCl and 1.5 mM trisodium citrate. Stringent temperature conditions for the wash steps will ordinarily include a temperature of at least about 25° C, more preferably of at least about 42° C, and even more preferably of at least about 68° C In a preferred embodiment, wash steps will occur at 25° C in 30 mM NaCl, 3 mM trisodium citrate, and 0.1% SDS. In a more preferred embodiment, wash steps will occur at 42° C in 15 mM NaCl, 1.5 mM trisodium citrate, and 0.1% SDS. In a more preferred embodiment, wash steps will occur at 68° C in 15 mM NaCl, 1.5 mM trisodium citrate, and 0.1 % SDS. Additional variations on these conditions will be readily apparent to those skilled in the art. Hybridization techniques are well known to those skilled in the art and are described, for example, in Benton and Davis (Science 196: 180, 1977); Grunstein and Hogness (Proc. Natl. Acad. Sci., USA 72:3961, 1975); Ausubel et al. (Current Protocols in Molecular Biology, Wiley Interscience, New York, 2001); Berger and Kimmel (Guide to Molecular Cloning Techniques, 1987, Academic Press, New York); and Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory Press, New York.

By "substantially identical" is meant a polypeptide or nucleic acid molecule exhibiting at least 50% identity to a reference amino acid sequence (for example, any one of the amino acid sequences described herein) or nucleic acid sequence (for example, any one of the nucleic acid sequences described herein). Preferably, such a sequence is at least 60%, more preferably 80% or 85%, and more preferably 90%, 95%, 96%, 97%, 98%, or even 99% or more identical at the amino acid level or nucleic acid to the sequence used for comparison.

Sequence identity is typically measured using sequence analysis software (for example,

Sequence Analysis Software Package of the Genetics Computer Group, University of Wisconsin Biotechnology Center, 1710 University Avenue, Madison, Wis. 53705, BLAST, BESTFIT, GAP, or PILEUP/PRETTYBOX programs). Such software matches identical or similar sequences by assigning degrees of homology to various substitutions, deletions, and/or other modifications. Conservative substitutions typically include substitutions within the following groups: glycine, alanine; valine, isoleucine, leucine; aspartic acid, glutamic acid, asparagine, glutamine; serine, threonine; lysine, arginine; and phenylalanine, tyrosine. In an exemplary approach to determining the degree of identity, a BLAST program may be used, with a probability score between e^"3 and e^"100 indicating a closely related sequence.

As used herein, the term "sample" includes a biologic sample such as any tissue, cell, fluid, or other material derived from an organism.

By "specifically binds" is meant a compound (e.g., antibody) that recognizes and binds a molecule (e.g., polypeptide), but which does not substantially recognize and bind other molecules in a sample, for example, a biological sample. For example, two molecules that specifically bind form a complex that is relatively stable under physiologic conditions. Specific binding is characterized by a high affinity and a low to moderate capacity as distinguished from nonspecific binding which usually has a low affinity with a moderate to high capacity. Typically, binding is considered specific when the affinity constant KA higher than 10⁶ M^_1, or more

8

preferably higher than 10 M . If necessary, non-specific binding can be reduced without substantially affecting specific binding by varying the binding conditions. The appropriate binding conditions such as concentration of antibodies, ionic strength of the solution, temperature, time allowed for binding, concentration of a blocking agent (e.g., serum albumin, milk casein), etc., may be optimized by a skilled artisan using routine techniques.

Unless specifically stated or obvious from context, as used herein, the term "about" is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. About can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from context, all numerical values provided herein are modified by the term about.

Ranges provided herein are understood to be shorthand for all of the values within the range. For example, a range of 1 to 50 is understood to include any number, combination of numbers, or sub-range from the group consisting 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50.

Any compounds, compositions, or methods provided herein can be combined with one or more of any of the other compositions and methods provided herein.

As used herein, the singular forms "a", "an", and "the" include plural forms unless the context clearly dictates otherwise. Thus, for example, reference to "a biomarker" includes reference to more than one biomarker.

Unless specifically stated or obvious from context, as used herein, the term "or" is understood to be inclusive.

The term "including" is used herein to mean, and is used interchangeably with, the phrase "including but not limited to."

As used herein, the terms "comprises," "comprising," "containing," "having" and the like can have the meaning ascribed to them in U.S. Patent law and can mean "includes," "including," and the like; "consisting essentially of or "consists essentially" likewise has the meaning ascribed in U.S. Patent law and the term is open-ended, allowing for the presence of more than that which is recited so long as basic or novel characteristics of that which is recited is not changed by the presence of more than that which is recited, but excludes prior art embodiments. DETAILED DESCRIPTION OF THE INVENTION

The invention features antibodies that can act as antagonists of PD-1 or a PD-1 pathway, thereby modulating immune responses regulated by PD-1. The disclosure further provides anti- PD-1 antibodies that comprise novel antigen-binding fragments. Anti-PD-1 antibodies of the invention are capable of (a) specifically binding to PD-1, including human PD-1; (b) blocking PD-1 interactions with its natural ligand(s) (e.g., PD-L1, PD-L2); or (c) performing both functions. Furthermore, the antibodies possess immunomodulatory properties, i.e., they are effective in modulating PD-1 -associated immune responses. Depending on the method of use and the desired effect, the antibodies may be used to either enhance or inhibit immune responses.

A nonlimiting, illustrative embodiment of the antibodies of the invention is referred to herein as LOPD180. Other embodiments comprise a V_H and/or V_L domain of the Fv fragment of LOPD180. Further embodiments comprise one or more complementarity determining regions (CDRs) of any of these V_H and V_L domains. Other embodiments comprise an H3 fragment of the V_H domain of LOPD180.

The disclosure also provides compositions comprising anti-PD-1 antibodies, and their use in methods of modulating immune response, including methods of treating humans or animals. In particular embodiments, anti-PD-1 antibodies are used to treat or prevent immune disorders by virtue of increasing or reducing the T cell response mediated by TcR/CD28. Disorders susceptible to treatment with compositions of the invention include but are not limited to rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease, Crohn's disease, systemic lupus erythematosis, type I diabetes, transplant rejection, graft-versus-host disease,

hyperproliferative immune disorders, cancer, and infectious diseases.

Additionally, anti-PD-1 antibodies may be used diagnostically to detect PD-1 or its fragments in a biological sample. The amount of PD-1 detected may be correlated with the expression level of PD-1, which, in turn, is correlated with the activation status of immune cells (e.g., activated T cells, B cells, and monocytes) in the subject.

The disclosure also provides isolated nucleic acids, which comprise a sequence encoding a V_H or V_L domain from the Fv fragment of LOPD180. Also provided are isolated nucleic acids, which comprise a sequence encoding one or more CDRs from any of the presently disclosed V_H and V_L domains. The disclosure also provides vectors and host cells comprising such nucleic acids.

The disclosure further provides a method of producing new V_H and V_L domains and/or functional antibodies comprising all or a portion of such domains derived from the V_H or V_L domains of LOPD 180.

Additional aspects of the disclosure will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practicing the invention. The invention is set forth and particularly pointed out in the appended claims, and the present disclosure should not be construed as limiting the scope of the claims in any way. The following detailed description includes exemplary representations of various embodiments of the invention, which are not restrictive of the invention, as claimed. The accompanying figures constitute a part of this specification and, together with the description, serve only to illustrate various embodiments and not limit the invention. Citation of references is not an admission that these references are prior art to the invention.

PD-1 (Programmed Death 1)

PD-1 (Programmed Death 1) is an inhibitory receptor and a counterpart of CTLA-4. This disclosure relates to modulation of immune responses mediated by the PD-1 receptor.PD-1 is a 50-55 kDa type I transmembrane receptor that was originally identified in a T cell line undergoing activation-induced apoptosis. PD-1 is expressed on T cells, B cells, and

macrophages. The ligands for PD-1 are the B7 family members PD-L1 (B7-H1) and PD-L2 (B7- DC).

In general, a need exists to provide safe and effective therapeutic methods for immune disorders such as, for example, sepsis, autoimmune diseases, inflammatory disorders, allergies, transplant rejection, cancer, immune deficiency, and other immune system-related disorders. Modulation of the immune responses involved in these disorders can be accomplished by manipulation of the PD-1 pathway.

Programmed cell death 1 ligand 1 (PD-L1)

Two forms of human PD-L1 molecules have been identified (Freeman et al. J. Exp. Med.

2000. 192: 1027; Dong et al. 1999. Nature Medicine. 5: 1365). One form is a naturally occurring PD-L1 soluble polypeptide, i.e., having a short hydrophilic domain and no transmembrane domain, and is referred to herein as soluble PD-L1. The second form is a cell-associated polypeptide, i.e., having a transmembrane and cytoplasmic domain, referred to herein as PD-L1. PD-L2 molecules have also been identified. (Genbank Accession no. AF344424; Latchman et al.

2001. Nature Immunology. 2:1). Anti-PD-1 Antibodies

The disclosure provides anti-PD-1 antibodies that comprise novel antigen-binding fragments. In a particular embodiment, the anti-PDl antibody is LOPD180.

In general, antibodies can be made, for example, using traditional hybridoma techniques (Kohler and Milstein (1975) Nature, 256: 495-499), recombinant DNA methods (U.S. Pat. No. 4,816,567), or phage display performed with antibody, libraries (Clackson et al. (1991) Nature, 352: 624-628; Marks et al. (1991) J. Mol. Biol., 222: 581-597). For other antibody production techniques, see also Antibodies: A Laboratory Manual, eds. Harlow et al., Cold Spring Harbor Laboratory, 1988. The invention is not limited to any particular source, species of origin, method of production.

Intact antibodies, also known as immunoglobulins, are typically tetrameric glycosylated proteins composed of two light (L) chains of approximately 25 kDa each and two heavy (H) chains of approximately 50 kDa each. Two types of light chain, designated as the λ chain and the K chain, are found in antibodies. Depending on the amino acid sequence of the constant domain of heavy chains, immunoglobulins can be assigned to five major classes: A, D, E, G, and M, and several of these may be further divided into subclasses (isotypes), e.g., IgGi, IgG₂, IgG₃, IgG₄, IgAi, and IgA₂.

The subunit structures and three-dimensional configurations of different classes of immunoglobulins are well known in the art. For a review of antibody structure, see Harlow et al., supra. Briefly, each light chain is composed of an N-terminal variable domain (V_L) and a constant domain (C_L). Each heavy chain is composed of an N-terminal variable domain (V_H), three or four constant domains (C_H), and a hinge region. The C_H domain most proximal to Vjjis designated as Cjjl- The Vjj and V_L domains consist of four regions of relatively conserved sequence called framework regions (FR1, FR2, FR3, and FR4), which form a scaffold for three regions of hypervariable sequence called complementarity determining regions (CDRs). The CDRs contain most of the residues responsible for specific interactions with the antigen. The three CDRs are referred to as CDR1, CDR2, and CDR3. CDR constituents on the heavy chain are referred to as HI, H2, and H3, while CDR constituents on the light chain are referred to as LI, L2, and L3, accordingly. CDR3 and, particularly H3, are the greatest source of molecular diversity within the antigen-binding domain. H3, for example, can be as short as two amino acid residues or greater than 26.

The Fab fragment (Fragment antigen-binding) consists of the V_H-C_H1 and V_L-C_L domains covalently linked by a disulfide bond between the constant regions. To overcome the tendency of non-covalently linked V_H and V_L domains in the Fv to dissociate when co-expressed in a host cell, a so-called single chain (sc) Fv fragment (scFv) can be constructed. In a scFv, a flexible and adequately long polypeptide links either the C-terminus of the V_H to the N-terminus of the V_L or the C-terminus of the V_Lto the N-terminus of the V_H- Most commonly, a 15-residue (Gly₄Ser)₃ peptide is used as a linker but other linkers are also known in the art.

Antibody diversity is a result of combinatorial assembly of multiple germline genes encoding variable regions and a variety of somatic events. The somatic events include recombination of variable gene segments with diversity (D) and joining (J) gene segments to make a complete V_H region and the recombination of variable and joining gene segments to make a complete V_L region. The recombination process itself is imprecise, resulting in the loss or addition of amino acids at the V(D)J junctions. These mechanisms of diversity occur in the developing B cell prior to antigen exposure. After antigenic stimulation, the expressed antibody genes in B cells undergo somatic mutation.

Based on the estimated number of germline gene segments, the random recombination of these segments, and random V_H-V_L pairing, up to 1.6x10 different antibodies could be produced (Fundamental Immunology, 3rd ed., ed. Paul, Raven Press, New York, N.Y., 1993). When other processes which contribute to antibody diversity (such as somatic mutation) are taken into account, it is thought that upwards of lxlO¹⁰ different antibodies could be potentially generated (Immunoglobulin Genes, 2^nd ed., eds. Jonio et al., Academic Press, San Diego, Calif., 1995). Because of the many processes involved in antibody diversity, it is highly unlikely that independently generated antibodies will have identical or even substantially similar amino acid sequences in the CDRs.

The disclosure provides novel CDRs derived from human immunoglobulin gene libraries.

The structure for carrying a CDR will generally be an antibody heavy or light chain or a portion thereof, in which the CDR is located at a location corresponding to the CDR of naturally occurring V_H and V_L- The structures and locations of immunoglobulin variable domains may be determined, for example, as described in Kabat et al., Sequences of Proteins of Immunological Interest, No. 91-3242, National Institutes of Health Publications, Bethesda, Md., 1991.

DNA and amino acid sequences of anti-PD-1 antibodies V_H and V_L domains are set forth below. Particular nonlimiting illustrative embodiments of the antibodies include LOPD180 and fragments and derivatives thereof. PD-1 polypeptide sequence [SEQ ID NO: 1] LOCUS NP_005009 288 aa linear

DEFINITION programmed cell death protein 1 precursor [Homo sapiens]

ORIGIN

1 mgipgapwpv vwavlglgwr pgwfldspdr pwnpptfspa llvvtegdna tftcsfsnts

61 esfvlnwyrm spsngtdkla afpedrsgpg gdcrfrvtgl pngrdfhmsv vrarrndsgt

121 ylcgaislap kagikeslra elrvterrae vptahpspsp rpaggfgtlv vgvvggllgs

181 lvllvwvlav icsraargti garrtggplk edpsavpvfs vdygeldfgw rektpeppvp

241 cvpegteyat ivfpsgmgts sparrgsadg prsagplrpe dghcswpl

PD-1 nucleic acid sequence [SEQ ID NO: 2]

LOCUS NM_005018 2115 bp mRNA linear

DEFINITION Homo sapiens programmed cell death 1 (PDCD1), mRNA.

ORIGIN

1 agtttccctt ccgctcacct ccgcctgagc agtggagaag gcggcactct ggtggggctg

61 ctccaggcat gcagatccca caggcgccct ggccagtcgt ctgggcggtg ctacaactgg

121 gctggcggcc aggatggttc ttagactccc cagacaggcc ctggaacccc cccaccttct

181 ccccagccct gctcgtggtg accgaagggg acaacgccac cttcacctgc agcttctcca

241 acacatcgga gagcttcgtg ctaaactggt accgcatgag ccccagcaac cagacggaca

301 agctggccgc cttccccgag gaccgcagcc agcccggcca ggactgccgc ttccgtgtca

361 cacaactgcc caacgggcgt gacttccaca tgagcgtggt cagggcccgg cgcaatgaca

421 gcggcaccta cctctgtggg gccatctccc tggcccccaa ggcgcagatc aaagagagcc

481 tgcgggcaga gctcagggtg acagagagaa gggcagaagt gcccacagcc caccccagcc

541 cctcacccag gccagccggc cagttccaaa ccctggtggt tggtgtcgtg ggcggcctgc

601 tgggcagcct ggtgctgcta gtctgggtcc tggccgtcat ctgctcccgg gccgcacgag

661 ggacaatagg agccaggcgc accggccagc ccctgaagga ggacccctca gccgtgcctg

721 tgttctctgt ggactatggg gagctggatt tccagtggcg agagaagacc ccggagcccc

781 ccgtgccctg tgtccctgag cagacggagt atgccaccat tgtctttcct agcggaatgg

841 gcacctcatc ccccgcccgc aggggctcag ctgacggccc tcggagtgcc cagccactga

901 ggcctgagga tggacactgc tcttggcccc tctgaccggc ttccttggcc accagtgttc

961 tgcagaccct ccaccatgag cccgggtcag cgcatttcct caggagaagc aggcagggtg

1021 caggccattg caggccgtcc aggggctgag ctgcctgggg gcgaccgggg ctccagcctg

1081 cacctgcacc aggcacagcc ccaccacagg actcatgtct caatgcccac agtgagccca

1141 ggcagcaggt gtcaccgtcc cctacaggga gggccagatg cagtcactgc ttcaggtcct

1201 gccagcacag agctgcctgc gtccagctcc ctgaatctct gctgctgctg ctgctgctgc

1261 tgctgctgcc tgcggcccgg ggctgaaggc gccgtggccc tgcctgacgc cccggagcct

1321 cctgcctgaa cttgggggct ggttggagat ggccttggag cagccaaggt gcccctggca

1381 gtggcatccc gaaacgccct ggacgcaggg cccaagactg ggcacaggag tgggaggtac

1441 atggggctgg ggactcccca ggagttatct gctccctgca ggcctagaga agtttcaggg

1501 aaggtcagaa gagctcctgg ctgtggtggg cagggcagga aacccctcca cctttacaca

1561 tgcccaggca gcacctcagg ccctttgtgg ggcagggaag ctgaggcagt aagcgggcag

1621 gcagagctgg aggcctttca ggcccagcca gcactctggc ctcctgccgc cgcattccac

1681 cccagcccct cacaccactc gggagaggga catcctacgg tcccaaggtc aggagggcag 1741 ggctggggtt gactcaggcc cctcccagct gtggccacct gggtgttggg agggcagaag

1801 tgcaggcacc tagggccccc catgtgccca ccctgggagc tctccttgga acccattcct

1861 gaaattattt aaaggggttg gccgggctcc caccagggcc tgggtgggaa ggtacaggcg

1921 ttcccccggg gcctagtacc cccgccgtgg cctatccact cctcacatcc acacactgca

1981 cccccactcc tggggcaggg ccaccagcat ccaggcggcc agcaggcacc tgagtggctg

2041 ggacaaggga tcccccttcc ctgtggttct attatattat aattataatt aaatatgaga

2101 gcatgctaag gaaaa

PD-L1 polypeptide sequence [SEQ ID NO: 3]

LOCUS NP_001254635 176 aa linear

DEFINITION programmed cell death 1 ligand 1 isoform b precursor [Homo

sapiens] .

ORIGIN

1 mrifavfifm tywhllnapy nkinqrilvv dpvtsehelt cqaegypkae viwtssdhqv

61 lsgkttttns kreeklfnvt stlrintttn eifyctfrrl dpeenhtael vipelplahp

121 pnerthlvil gaillclgva ltfifrlrkg rmmdvkkcgi qdtnskkqsd thleet

PD-L1 nucleic acid sequence [SEQ ID NO: 4]

LOCUS NM_001267706 3349 bp mRNA linear

DEFINITION Homo sapiens CD274 molecule (CD274), transcript variant 2, mRNA.

ORIGIN

1 ggcgcaacgc tgagcagctg gcgcgtcccg cgcggcccca gttctgcgca gcttcccgag

61 gctccgcacc agccgcgctt ctgtccgcct gcagggcatt ccagaaagat gaggatattt

121 gctgtcttta tattcatgac ctactggcat ttgctgaacg ccccatacaa caaaatcaac

181 caaagaattt tggttgtgga tccagtcacc tctgaacatg aactgacatg tcaggctgag

241 ggctacccca aggccgaagt catctggaca agcagtgacc atcaagtcct gagtggtaag

301 accaccacca ccaattccaa gagagaggag aagcttttca atgtgaccag cacactgaga

361 atcaacacaa caactaatga gattttctac tgcactttta ggagattaga tcctgaggaa

421 aaccatacag ctgaattggt catcccagaa ctacctctgg cacatcctcc aaatgaaagg

481 actcacttgg taattctggg agccatctta ttatgccttg gtgtagcact gacattcatc

541 ttccgtttaa gaaaagggag aatgatggat gtgaaaaaat gtggcatcca agatacaaac

601 tcaaagaagc aaagtgatac acatttggag gagacgtaat ccagcattgg aacttctgat

661 cttcaagcag ggattctcaa cctgtggttt aggggttcat cggggctgag cgtgacaaga

721 ggaaggaatg ggcccgtggg atgcaggcaa tgtgggactt aaaaggccca agcactgaaa

781 atggaacctg gcgaaagcag aggaggagaa tgaagaaaga tggagtcaaa cagggagcct

841 ggagggagac cttgatactt tcaaatgcct gaggggctca tcgacgcctg tgacagggag

901 aaaggatact tctgaacaag gagcctccaa gcaaatcatc cattgctcat cctaggaaga

961 cgggttgaga atccctaatt tgagggtcag ttcctgcaga agtgcccttt gcctccactc

1021 aatgcctcaa tttgttttct gcatgactga gagtctcagt gttggaacgg gacagtattt

1081 atgtatgagt ttttcctatt tattttgagt ctgtgaggtc ttcttgtcat gtgagtgtgg

1141 ttgtgaatga tttcttttga agatatattg tagtagatgt tacaattttg tcgccaaact

1201 aaacttgctg cttaatgatt tgctcacatc tagtaaaaca tggagtattt gtaaggtgct 1261 tggtctcctc tataactaca agtatacatt ggaagcataa agatcaaacc gttggttgca

1321 taggatgtca cctttattta acccattaat actctggttg acctaatctt attctcagac

1381 ctcaagtgtc tgtgcagtat ctgttccatt taaatatcag ctttacaatt atgtggtagc

1441 ctacacacat aatctcattt catcgctgta accaccctgt tgtgataacc actattattt

1501 tacccatcgt acagctgagg aagcaaacag attaagtaac ttgcccaaac cagtaaatag

1561 cagacctcag actgccaccc actgtccttt tataatacaa tttacagcta tattttactt

1621 taagcaattc ttttattcaa aaaccattta ttaagtgccc ttgcaatatc aatcgctgtg

1681 ccaggcattg aatctacaga tgtgagcaag acaaagtacc tgtcctcaag gagctcatag

1741 tataatgagg agattaacaa gaaaatgtat tattacaatt tagtccagtg tcatagcata

1801 aggatgatgc gaggggaaaa cccgagcagt gttgccaaga ggaggaaata ggccaatgtg

1861 gtctgggacg gttggatata cttaaacatc ttaataatca gagtaatttt catttacaaa

1921 gagaggtcgg tacttaaaat aaccctgaaa aataacactg gaattccttt tctagcatta

1981 tatttattcc tgatttgcct ttgccatata atctaatgct tgtttatata gtgtctggta

2041 ttgtttaaca gttctgtctt ttctatttaa atgccactaa attttaaatt catacctttc

2101 catgattcaa aattcaaaag atcccatggg agatggttgg aaaatctcca cttcatcctc

2161 caagccattc aagtttcctt tccagaagca actgctactg cctttcattc atatgttctt

2221 ctaaagatag tctacatttg gaaatgtatg ttaaaagcac gtatttttaa aatttttttc

2281 ctaaatagta acacattgta tgtctgctgt gtactttgct atttttattt attttagtgt

2341 ttcttatata gcagatggaa tgaatttgaa gttcccaggg ctgaggatcc atgccttctt

2401 tgtttctaag ttatctttcc catagctttt cattatcttt catatgatcc agtatatgtt

2461 aaatatgtcc tacatataca tttagacaac caccatttgt taagtatttg ctctaggaca

2521 gagtttggat ttgtttatgt ttgctcaaaa ggagacccat gggctctcca gggtgcactg

2581 agtcaatcta gtcctaaaaa gcaatcttat tattaactct gtatgacaga atcatgtctg

2641 gaacttttgt tttctgcttt ctgtcaagta taaacttcac tttgatgctg tacttgcaaa

2701 atcacatttt ctttctggaa attccggcag tgtaccttga ctgctagcta ccctgtgcca

2761 gaaaagcctc attcgttgtg cttgaaccct tgaatgccac cagctgtcat cactacacag

2821 ccctcctaag aggcttcctg gaggtttcga gattcagatg ccctgggaga tcccagagtt

2881 tcctttccct cttggccata ttctggtgtc aatgacaagg agtaccttgg ctttgccaca

2941 tgtcaaggct gaagaaacag tgtctccaac agagctcctt gtgttatctg tttgtacatg

3001 tgcatttgta cagtaattgg tgtgacagtg ttctttgtgt gaattacagg caagaattgt

3061 ggctgagcaa ggcacatagt ctactcagtc tattcctaag tcctaactcc tccttgtggt

3121 gttggatttg taaggcactt tatccctttt gtctcatgtt tcatcgtaaa tggcataggc

3181 agagatgata cctaattctg catttgattg tcactttttg tacctgcatt aatttaataa

3241 aatattctta tttattttgt tacttggtac accagcatgt ccattttctt gtttattttg

3301 tgtttaataa aatgttcagt ttaacatccc agtggagaaa gttaaaaaa

PD-L2 polypeptide sequence [SEQ ID NO: 5]

LOCUS NP_079515 273 aa linear

DEFINITION programmed cell death 1 ligand 2 precursor [Homo sapiens] .

ORIGIN

1 miflllmlsl elglhgiaal ftvtvpkely iiehgsnvtl ecnfdtgshv nlgaitaslg

61 kvendtsphr eratlleegl plgkasfhip gvgvrdeggy gciiiygvaw dykyltlkvk

121 asyrkinthi lkvpetdeve ltcgatgypl aevswpnvsv pantshsrtp eglygvtsvl

181 rlkpppgrnf scvfwnthvr eltlasidlq sqmeprthpt wllhifipfc iiafifiatv 241 ialrkqlcqk lysskdttkr pvtttkrevn sai

PD-L2 nucleic acid sequence [SEQ ID NO: 6]

LOCUS NM_025239 2418 bp mRNA linear

DEFINITION Homo sapiens programmed cell death 1 ligand 2 (PDCD1LG2), mRNA.

ORIGIN

1 gcaaacctta agctgaatga acaacttttc ttctcttgaa tatatcttaa cgccaaattt

61 tgagtgcttt tttgttaccc atcctcatat gtcccagcta gaaagaatcc tgggttggag

121 ctactgcatg ttgattgttt tgtttttcct tttggctgtt cattttggtg gctactataa

181 ggaaatctaa cacaaacagc aactgttttt tgttgtttac ttttgcatct ttacttgtgg

241 agctgtggca agtcctcata tcaaatacag aacatgatct tcctcctgct aatgttgagc

301 ctggaattgc agcttcacca gatagcagct ttattcacag tgacagtccc taaggaactg

361 tacataatag agcatggcag caatgtgacc ctggaatgca actttgacac tggaagtcat

421 gtgaaccttg gagcaataac agccagtttg caaaaggtgg aaaatgatac atccccacac

481 cgtgaaagag ccactttgct ggaggagcag ctgcccctag ggaaggcctc gttccacata

541 cctcaagtcc aagtgaggga cgaaggacag taccaatgca taatcatcta tggggtcgcc

601 tgggactaca agtacctgac tctgaaagtc aaagcttcct acaggaaaat aaacactcac

661 atcctaaagg ttccagaaac agatgaggta gagctcacct gccaggctac aggttatcct

721 ctggcagaag tatcctggcc aaacgtcagc gttcctgcca acaccagcca ctccaggacc

781 cctgaaggcc tctaccaggt caccagtgtt ctgcgcctaa agccaccccc tggcagaaac

841 ttcagctgtg tgttctggaa tactcacgtg agggaactta ctttggccag cattgacctt

901 caaagtcaga tggaacccag gacccatcca acttggctgc ttcacatttt catccccttc

961 tgcatcattg ctttcatttt catagccaca gtgatagccc taagaaaaca actctgtcaa

1021 aagctgtatt cttcaaaaga cacaacaaaa agacctgtca ccacaacaaa gagggaagtg

1081 aacagtgcta tctgaacctg tggtcttggg agccagggtg acctgatatg acatctaaag

1141 aagcttctgg actctgaaca agaattcggt ggcctgcaga gcttgccatt tgcacttttc

1201 aaatgccttt ggatgaccca gcactttaat ctgaaacctg caacaagact agccaacacc

1261 tggccatgaa acttgcccct tcactgatct ggactcacct ctggagccta tggctttaag

1321 caagcactac tgcactttac agaattaccc cactggatcc tggacccaca gaattccttc

1381 aggatccttc ttgctgccag actgaaagca aaaggaatta tttcccctca agttttctaa

1441 gtgatttcca aaagcagagg tgtgtggaaa tttccagtaa cagaaacaga tgggttgcca

1501 atagagttat tttttatcta tagcttcctc tgggtactag aagaggctat tgagactatg

1561 agctcacaga cagggcttcg cacaaactca aatcataatt gacatgtttt atggattact

1621 ggaatcttga tagcataatg aagttgttct aattaacaga gagcatttaa atatacacta

1681 agtgcacaaa ttgtggagta aagtcatcaa gctctgtttt tgaggtctaa gtcacaaagc

1741 atttgtttta acctgtaatg gcaccatgtt taatggtggt tttttttttg aactacatct

1801 ttcctttaaa aattattggt ttctttttat ttgtttttac cttagaaatc aattatatac

1861 agtcaaaaat atttgatatg ctcatacgtt gtatctgcag caatttcaga taagtagcta

1921 aaatggccaa agccccaaac taagcctcct tttctggccc tcaatatgac tttaaatttg

1981 acttttcagt gcctcagttt gcacatctgt aatacagcaa tgctaagtag tcaaggcctt

2041 tgataattgg cactatggaa atcctgcaag atcccactac atatgtgtgg agcagaaggg

2101 taactcggct acagtaacag cttaattttg ttaaatttgt tctttatact ggagccatga

2161 agctcagagc attagctgac ccttgaacta ttcaaatggg cacattagct agtataacag

2221 acttacatag gtgggcctaa agcaagctcc ttaactgagc aaaatttggg gcttatgaga

2281 atgaaagggt gtgaaattga ctaacagaca aatcatacat ctcagtttct caattctcat

2341 gtaaatcaga gaatgccttt aaagaataaa actcaattgt tattcttcaa cgttctttat 2401 atattctact tttgggta

LOPD180 heavy chain variable region polypeptide sequence [SEQ ID NO: 7]

LOPD180_VH_AA

QVQLQESGPGLVKPSQTLSLTCTVSGGSISSGAYYWSWIRQHPGKGLEWIGYIYYNGNTYYNPSLRSRVTISVDTSK NQFSLKLSSVTAADTAVYYCVRASDYVWGGYHYFDAFDLWGRGTLVTVSS

LOPD180 heavy chain variable region nucleic acid sequence [SEQ ID NO: 8]

LOPD180_VH_DNA

CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCACAGACCCTGTCCCTCACCTGCACTGTCTCTGG TGGCTCCATCAGCAGTGGTGCTTATTACTGGAGCTGGATCCGCCAGCACCCAGGGAAGGGCCTGGAGTGGATTGGGT ACATCTATTACAATGGGAACACGTACTACAACCCGTCCCTCAGGAGTCGAGTTACCATATCAGTAGACACGTCTAAG AACCAGTTCTCCCTGAAGCTGAGCTCTGTGACTGCCGCGGACACGGCCGTCTATTACTGTGTGAGAGCGTCTGATTA CGTTTGGGGGGGTTATCATTATTTCGACGCGTTCGACCTCTGGGGCCGGGGAACCCTGGTCACCGTCTCCTCA

LOPD180 light chain variable region polypeptide sequence [SEQ ID NO: 9]

LOPD180_VL_AA

QSVLTQPPSASGTPGQRVTISCSGSNSNIGSNSVNWYQQLPGTAPKLLIYGNNQRPSGVPDRFSGSKSGTSASLAIS GLQSEDEADYYCAAWDDSLNGPVFGGGTKVTVL

LOPD180 light chain variable region nucleic acid sequence [SEQ ID NO: 10]

LOPD180_VL_DNA

CAGTCTGTGCTGACTCAGCCACCCTCAGCGTCTGGGACCCCCGGGCAGAGGGTCACCATCTCTTGTTCTGGAAGCAA CTCCAACATCGGAAGTAATTCTGTAAACTGGTACCAGCAGCTCCCAGGAACGGCCCCCAAACTCCTCATCTATGGTA ATAATCAGCGGCCCTCAGGGGTCCCTGACCGATTCTCTGGCTCCAAGTCTGGCACCTCAGCCTCCCTGGCCATCAGT GGGCTCCAGTCTGAGGATGAGGCTGATTATTACTGTGCAGCATGGGATGACAGCCTGAATGGTCCGGTATTCGGCGG AGGGACCAAGGTCACCGTCCTA

LOPD180 heavy chain polypeptide sequence [SEQ ID NO: 11]

LOPD180 HC pEU15.1-TM za allotype

Average Mass = 50087.4406, Monoisotopic Mass = 50055.8736

Modified amino acids: Pyr(J) = Pyroglutamic acid

1 JVQLQ ESGPG LVKPS QTLSL TCTVS GGSIS SGAYY WSWIR QHPGK GLEWI 51 GYIYY NGNTY YNPSL RSRVT ISVDT SKNQF SLKLS SVTAA DTAVY YCVRA

101 SDYVW GGYHY FDAFD LWGRG TLVTV SSAST KGPSV FPLAP SSKST SGGTA

151 ALGCL VKDYF PEPVT VSWNS GALTS GVHTF PAVLQ SSGLY SLSSV VTVPS

201 SSLGT QTYIC NVNHK PSNTK VDKKV EPKSC DKTHT CPPCP APEFE GGPSV

251 FLFPP KPKDT LMISR TPEVT CWVD VSHED PEVKF NWYVD GVEVH NAKTK

301 PREEQ YNSTY RWSV LTVLH QDWLN GKEYK CKVSN KALPA SIEKT ISKAK

351 GQPRE PQVYT LPPSR DELTK NQVSL TCLVK GFYPS DIAVE WESNG QPENN

401 YKTTP PVLDS DGSFF LYSKL TVDKS RWQQG NVFSC SVMHE ALHNH YTQKS

451 LSLSP G

LOPD180 light chain polypeptide sequence [SEQ ID NO: 12]

LOPD180 LC

Modified amino acids: Pyr(J) = Pyroglutamic acid

1 JSVLT QPPSA SGTPG QRVTI SCSGS NSNIG SNSVN WYQQL PGTAP KLLIY

51 GNNQR PSGVP DRFSG SKSGT SASLA ISGLQ SEDEA DYYCA AWDDS LNGPV

101 FGGGT KVTVL GQPKA APSVT LFPPS SEELQ ANKAT LVCLI SDFYP GAVTV

151 AWKAD SSPVK AGVET TTPSK QSNNK YAASS YLSLT PEQWK SHRSY SCQVT

201 HEGST VEKTV APTEC S

In certain embodiments, the isolated antibody or antigen-binding fragment thereof binds to a PD-1 polypeptide and comprises a VH and/or a VL, where the VH and/or VL are each identical to or each have at least 90%, 95%, or 98% identity to the VH and VL amino acid sequences of SEQ ID NOs: 7 and 9.

In further embodiments, the isolated antibody or antigen-binding fragment thereof binds to a PD-1 polypeptide and comprises a VH region comprising the HI, H2 and H3 regions of LOPD180, where HI corresponds to amino acids 31-37 of SEQ ID NO: 7, where H2

corresponds to amino acids 52-67 of SEQ ID NO: 7, and where H3 corresponds to amino acids 110-116 of SEQ ID NO: 7.

In further embodiments, the isolated antibody or antigen-binding fragment thereof binds to a PD-1 polypeptide and comprises a VL region comprising the LI, L2 and L3 regions of LOPD180, where LI corresponds to amino acids 23-35 of SEQ ID NO: 9, where L2 corresponds to amino acids 51-57 of SEQ ID NO: 9, and where L3 corresponds to amino acids 90-100 of SEQ ID NO: 9. In additional embodiments, the isolated antibody or antigen-binding fragment thereof binds to a PD-1 polypeptide and comprises a VH region and a VL region wherein the VH region comprises the HI, H2 and H3 regions of LOPD180, where HI corresponds to amino acids 31-37 of SEQ ID NO: 7, where H2 corresponds to amino acids 52-67 of SEQ ID NO: 7, and where H3 corresponds to amino acids 110-116 of SEQ ID NO: 7.

In additional embodiments, the isolated antibody or antigen-binding fragment thereof binds to a PD-1 polypeptide and comprises a VH and a VL region where the VL region comprises the LI , L2 and L3 regions of LOPD180, where LI corresponds to amino acids 23-35 of SEQ ID NO: 9, where L2 corresponds to amino acids 51-57 of SEQ ID NO: 9, and where L3 corresponds to amino acids 90-100 of SEQ ID NO: 9.

In particular embodiments, the isolated antibody or antigen-binding fragment thereof binds to a PD-1 polypeptide and comprises a VH and a VL region where the VH region comprises the HI, H2 and H3 regions of LOPD180, where HI corresponds to amino acids 31-37 of SEQ ID NO: 7, where H2 corresponds to amino acids 52-67 of SEQ ID NO: 7, and where H3 corresponds to amino acids 110-116 of SEQ ID NO: 7 and the VL region comprises the LI , L2 and L3 regions of LOPD180, where LI corresponds to amino acids 23-35 of SEQ ID NO: 9, where L2 corresponds to amino acids 51-57 of SEQ ID NO: 9, and where L3 corresponds to amino acids 90-100 of SEQ ID NO: 9.

In certain embodiments, the isolated antibody or antigen-binding fragment thereof binds to a PD-1 polypeptide and comprises a H3, where the H3 corresponds to to amino acids 110-116 of SEQ ID NO: 7.

Anti-PD-1 antibodies may optionally comprise antibody constant regions or parts thereof. For example, a VL domain may have attached, at its C terminus, antibody light chain constant domains including human CK or CX chains. Similarly, a specific antigen-binding domain based on a VH domain may have attached all or part of an immunoglobulin heavy chain derived from any antibody isotope, e.g., IgG, IgA, IgE, and IgM and any of the isotope sub-classes, which include but are not limited to, IgGi and IgG₄. In the exemplary embodiments, PD1-17, PD1-28, PD1-33, and PD1-35, antibodies comprise C-terminal fragments of heavy and light chains of human IgG a, while PD1-F2 comprises C-terminal fragments of heavy and light chains of human IgGi_K. The DNA and amino acid sequences for the C-terminal fragment of are well known in the art (see, e.g., Kabat et al., Sequences of Proteins of Immunological Interest, No. 91-3242,

National Institutes of Health Publications, Bethesda, Md., 1991). Nonlimiting exemplary sequences are set forth in Table 4 of U.S. Pat. No. 7,488,802, which is herein incorporated by reference in its entirety.

Certain embodiments comprise a V_H and/or V_L domain of an Fv fragment from

LOPD180. Further embodiments comprise at least one CDR of any of these Vjj and V_L domains.

Antibodies, comprising at least one of the CDR sequences set forth in Figure 1 are encompassed within the scope of this invention. An embodiment, for example, comprises an H3 fragment of the V_H domain of antibodies chosen from LOPD180.

In certain embodiments, the V_H and/or V_L domains may be germlined, i.e., the framework regions (FRs) of these domains are mutated using conventional molecular biology techniques to match those produced by the germline cells. In other embodiments, the framework sequences remain diverged from the consensus germline sequences.

In certain embodiments, the antibodies specifically bind an epitope within the

extracellular domain of human PD-1. The predicted extracellular domain consists of a sequence from about amino acid 21 to about amino acid 170 of PD-1 (Swissport Accession No. Q15116).

In certain other embodiments, the antibodies specifically bind an epitope within the extracellular domain of mouse PD-1, with an affinity of more than 10 7 M—1 , and preferably more than 108 M—1. The amino acid sequence of mouse PD-1 is set out forth at GenBank Accession No. NM 008798, and is as a whole about 60% identical to its human counterpart. In further embodiments, antibodies of the invention bind to the PD-L-binding domain of PD-1.

It is contemplated that antibodies of the invention may also bind with other proteins, including, for example, recombinant proteins comprising all or a portion of the PD-1

extracellular domain.

One of ordinary skill in the art will recognize that the antibodies of this invention may be used to detect, measure, and inhibit proteins that differ somewhat from PD-1. The antibodies are expected to retain the specificity of binding so long as the target protein comprises a sequence which is at least about 60%, 70%, 80%, 90%, 95%, or more identical to any sequence of at least 100, 80, 60, 40, or 20 of contiguous amino acids in the sequence set forth in SEQ ID NO: l. The percent identity is determined by standard alignment algorithms such as, for example, Basic Local Alignment Tool (BLAST) described in Altshul et al. (1990) J. Mol. Biol., 215: 403-410, the algorithm of Needleman et al. (1970) J. Mol. Biol., 48: 444-453, or the algorithm of Meyers et al. (1988) Comput. Appl. Biosci., 4: 11-17.

In addition to the sequence homology analyses, epitope mapping (see, e.g., Epitope Mapping Protocols, ed. Morris, Humana Press, 1996) and secondary and tertiary structure analyses can be carried out to identify specific 3D structures assumed by the disclosed antibodies and their complexes with antigens. Such methods include, but are not limited to, X-ray crystallography (Engstom (1974) Biochem. Exp. Biol., 11:7-13) and computer modeling of virtual representations of the presently disclosed antibodies (Fletterick et al. (1986) Computer Graphics and Molecular Modeling, in Current Communications in Molecular Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.).

Derivatives

This disclosure also provides a method for obtaining an antibody specific for PD-1. CDRs in such antibodies are not limited to the specific sequences of V_H and V_L identified herein, and may include variants of these sequences that retain the ability to specifically bind PD-1. Such variants may be derived from the sequences listed herein by a skilled artisan using techniques well known in the art. For example, amino acid substitutions, deletions, or additions, can be made in the FRs and/or in the CDRs. While changes in the FRs are usually designed to improve stability and immunogenicity of the antibody, changes in the CDRs are typically designed to increase affinity of the antibody for its target. Variants of FRs also include naturally occurring immunoglobulin allotypes. Such affinity-increasing changes may be determined empirically by routine techniques that involve altering the CDR and testing the affinity antibody for its target. For example, conservative amino acid substitutions can be made within any one of the disclosed CDRs. Various alterations can be made according to the methods described in

Antibody Engineering, 2^nd ed., Oxford University Press, ed. Borrebaeck, 1995. These include but are not limited to nucleotide sequences that are altered by the substitution of different codons that encode a functionally equivalent amino acid residue within the sequence, thus producing a "silent" change. For example, the nonpolar amino acids include alanine, leucine, isoleucine, valine, proline, phenylalanine, tryptophan, and methionine. The polar neutral amino acids include glycine, serine, threonine, cysteine, tyrosine, asparagine, and glutamine. The positively charged (basic) amino acids include arginine, lysine, and histidine. The negatively charged (acidic) amino acids include aspartic acid and glutamic acid. Substitutes for an amino acid within the sequence may be selected from other members of the class to which the amino acid belongs (see Table 2). Furthermore, any native residue in the polypeptide may also be substituted with alanine (see, e.g., MacLennan et al. (1998) Acta Physiol. Scand. Suppl. 643:55-67; Sasaki et al. (1998) Adv. Biophys. 35: 1-24).

Table 2.

Original Exemplary Typical

Residues Substitutions Substitutions

Ala (A) Val, Leu, Tie Val

Afg (R) Lys, Gin, Asn Lys

Asn (N) Gin Gin,

Asp (D) Glu Glu

Cys (C) Ser, Ak Ser

Gin (Q) As.n .Asn

Giy (G) Pro, Ala Ala

His (Ή) Asn, Gin, Lys, Arg Afg

lie (1) Leu, Val, Met, Ala, PJie, Norieuciiie Leu

Leu (L) Norieuciiie, lie, Val, Met, Ala, Plie lie

Lys (K) Arg, 1 ,4- Pianino-butyric Acid, Gin, Asn Arg

Met (M) Leu, Phe, lie Leu

Ptie (F) Leu, Val, He, Ala, Tyr Leu

Pro (F) Ala^" Gly

Ser (S) Thr, Ala, Cys Thr

T r (T) Ser Ser

Tip (W) Tyr, Plie Tyr

Tyr (Y) Trp, Plie, Thr, Ser Phe

Val (V) lie. Met, Leu, Plie, Ala, Norieuciiie Leu

Derivatives and analogs of antibodies of the invention can be produced by various techniques well known in the art, including recombinant and synthetic methods (Maniatis (1990) Molecular Cloning, A Laboratory Manual, 2^nd ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y., and Bodansky et al. (1995) The Practice of Peptide Synthesis, 2ⁿ ed., Spring Verlag, Berlin, Germany).

In one embodiment, a method for making a V_H domain which is an amino acid sequence variant of a V_H domain of the invention comprises a step of adding, deleting, substituting, or inserting one or more amino acids in the amino acid sequence of the presently disclosed V_H domain, optionally combining the V_H domain thus provided with one or more V_L domains, and testing the V_H domain or V_H V_L combination or combinations for a specific binding to PD-1 or and, optionally, testing the ability of such antigen-binding domain to modulate PD-1 activity. The V_L domain may have an amino acid sequence that is identical or is substantially to a polypeptide of the invention.

An analogous method can be employed in which one or more sequence variants of a V_L domain disclosed herein are combined with one or more V_H domains.

A further aspect of the disclosure provides a method of preparing antigen-binding fragment that specifically binds with PD-1. The method comprises:

(a) providing a starting repertoire of nucleic acids encoding a V_H domain that either includes a CDR3 to be replaced or lacks a CDR3 encoding region;

(b) combining the repertoire with a donor nucleic acid encoding an amino acid

sequence substantially as set out herein for a V_H CDR3 (i.e., H3) such that the donor nucleic acid is inserted into the CDR3 region in the repertoire, so as to provide a product repertoire of nucleic acids encoding a V_H domain;

(c) expressing the nucleic acids of the product repertoire;

(d) selecting a binding fragment specific for PD-1 ; and

(e) recovering the specific binding fragment or nucleic acid encoding it.

Again, an analogous method may be employed in which a V_L CDR3 (i.e., L3) of the invention is combined with a repertoire of nucleic acids encoding a V_L domain, which either include a CDR3 to be replaced or lack a CDR3 encoding region.

A sequence encoding a CDR of the invention (e.g., CDR3) may be introduced into a repertoire of variable domains lacking the respective CDR (e.g., CDR3), using recombinant DNA technology, for example, using methodology described by Marks et al. (Bio/Technology (1992) 10: 779-783). In particular, consensus primers directed at or adjacent to the 5' end of the variable domain area can be used in conjunction with consensus primers to the third framework region of human V_H genes to provide a repertoire of V_H variable domains lacking a CDR3. The repertoire may be combined with a CDR3 of a particular antibody. Using analogous techniques, the CDR3-derived sequences may be shuffled with repertoires of V_H or V_L domains lacking a CDR3, and the shuffled complete V_H or V_L domains combined with a cognate V_L or V_H domain to make the PD-1 -specific antibodies of the invention. The repertoire may then be displayed in a suitable host system such as the phage display system such as described in WO92/01047 so that suitable antigen-binding fragments can be selected.

Analogous shuffling or combinatorial techniques are also disclosed by Stemmer (Nature (1994) 370: 389-391), who describes the technique in relation to a β-lactamase gene but observes that the approach may be used for the generation of antibodies.

In further embodiments, one may generate novel Vn or V_L regions carrying one or more sequences derived from the sequences disclosed herein using random mutagenesis of one or more selected V_H and/or V_L genes. One such technique, error-prone PCR, is described by Gram et al. (Proc. Nat. Acad. Sci. U.S.A. (1992) 89: 3576-3580).

Another method that may be used is to direct mutagenesis to CDRs of V_H or V_L genes. Such techniques are disclosed by Barbas et al. (Proc. Nat. Acad. Sci. U.S.A. (1994) 91 : 3809- 3813) and Schier et al. (J. Mol. Biol. (1996) 263: 551-567).

Similarly, one or more, or all three CDRs may be grafted into a repertoire of V_H or V_L domains, which are then screened for an antigen-binding fragment specific for PD-1.

A portion of an immunoglobulin variable domain will comprise at least one of the CDRs substantially as set out herein and, optionally, intervening framework regions from the scFv fragments as set out herein. The portion may include at least about 50% of either or both of FRl and FR4, the 50% being the C-terminal 50% of FRl and the N-terminal 50% of FR4. Additional residues at the N-terminal or C-terminal end of the substantial part of the variable domain may be those not normally associated with naturally occurring variable domain regions. For example, construction of antibodies by recombinant DNA techniques may result in the introduction of N- or C-terminal residues encoded by linkers introduced to facilitate cloning or other manipulation steps. Other manipulation steps include the introduction of linkers to join variable domains to further protein sequences including immunoglobulin heavy chain constant regions, other variable domains (for example, in the production of diabodies), or proteinaceous labels as discussed in further detail below.

Although the embodiments illustrated in the Examples comprise a "matching" pair of V_H and V_L domains, a skilled artisan will recognize that alternative embodiments may comprise antigen-binding fragments containing only a single CDR from either V_L or V_H domain. Either one of the single chain specific binding domains can be used to screen for complementary domains capable of forming a two-domain specific antigen-binding fragment capable of, for example, binding to PD-1. The screening may be accomplished by phage display screening methods using the so-called hierarchical dual combinatorial approach disclosed in WO92/01047, in which an individual colony containing either an H or L chain clone is used to infect a complete library of clones encoding the other chain (L or H) and the resulting two-chain specific binding domain is selected in accordance with phage display techniques as described.

Anti-PDl antibodies described herein can be linked to another functional molecule, e.g., another peptide or protein (albumin, another antibody, etc.), toxin, radioisotope, cytotoxic or cytostatic agents. For example, the antibodies can be linked by chemical cross-linking or by recombinant methods. The antibodies may also be linked to one of a variety of nonproteinaceous polymers, e.g., polyethylene glycol, polypropylene glycol, or polyoxyalkylenes, in the manner set forth in U.S. Pat. Nos. 4,640,835; 4,496,689; 4,301,144; 4,670,417; 4,791,192; or 4,179,337. The antibodies can be chemically modified by covalent conjugation to a polymer, for example, to increase their circulating half-life. Exemplary polymers and methods to attach them are also shown in U.S. Pat. Nos. 4,766,106; 4,179,337; 4,495,285, and 4,609,546.

The disclosed antibodies may also be altered to have a glycosylation pattern that differs from the native pattern. For example, one or more carbohydrate moieties can be deleted and/or one or more glycosylation sites added to the original antibody. Addition of glycosylation sites to the presently disclosed antibodies may be accomplished by altering the amino acid sequence to contain glycosylation site consensus sequences known in the art. Another means of increasing the number of carbohydrate moieties on the antibodies is by chemical or enzymatic coupling of glycosides to the amino acid residues of the antibody. Such methods are described in WO 87/05330 and in Aplin et al. (1981) CRC Crit. Rev. Biochem., 22: 259-306. Removal of any carbohydrate moieties from the antibodies may be accomplished chemically or enzymatically, for example, as described by Hakimuddin et al. (1987) Arch. Biochem. Biophys., 259: 52; and Edge et al. (1981 ) Anal. Biochem., 1 18: 131 and by Thotakura et al. (1987) Meth. Enzymol., 138: 350. The antibodies may also be tagged with a detectable, or functional, label. Detectable labels include radiolabels such as ¹³¹I or ⁹⁹Tc, which may also be attached to antibodies using conventional chemistry. Detectable labels also include enzyme labels such as horseradish peroxidase or alkaline phosphatase. Detectable labels further include chemical moieties such as biotin, which may be detected via binding to a specific cognate detectable moiety, e.g., labeled avidin.

Typically, an amino acid is substituted by a related amino acid having similar charge, hydrophobic, or stereochemical characteristics. Such substitutions would be within the ordinary skills of an artisan. Unlike in CDRs, more substantial changes can be made in FRs without adversely affecting the binding properties of an antibody. Changes to FRs include, but are not limited to, humanizing a non-human derived or engineering certain framework residues that are important for antigen contact or for stabilizing the binding site, e.g., changing the class or subclass of the constant region, changing specific amino acid residues which might alter the effector function such as Fc receptor binding, e.g., as described in U.S. Pat. Nos. 5,624,821 and 5,648,260 and Lund et al. (1991) J. Immun. 147: 2657-2662 and Morgan et al. (1995)

Immunology 86: 319-324, or changing the species from which the constant region is derived.

One of skill in the art will appreciate that the modifications described above are not all- exhaustive, and that many other modifications would obvious to a skilled artisan in light of the teachings of the present disclosure.

Nucleic Acids, Cloning and Expression Systems

The present disclosure further provides isolated nucleic acids encoding the disclosed antibodies. The nucleic acids may comprise DNA or RNA and may be wholly or partially synthetic or recombinant. Reference to a nucleotide sequence as set out herein encompasses a DNA molecule with the specified sequence, and encompasses a RNA molecule with the specified sequence in which U is substituted for T, unless context requires otherwise.

The nucleic acids provided herein comprise a coding sequence for a CDR, a V_H domain, and/or a V_L domain disclosed herein. The present disclosure also provides constructs in the form of plasmids, vectors, phagemids, transcription or expression cassettes which comprise at least one nucleic acid encoding a CDR, a V_H domain, and/or a V_L domain disclosed herein.

The disclosure further provides a host cell which comprises one or more constructs as above.

Also provided are nucleic acids encoding any CDR (HI, H2, H3, LI, L2, or L3), V_H or V_L domain, as well as methods of making of the encoded products. The method comprises expressing the encoded product from the encoding nucleic acid. Expression may be achieved by culturing under appropriate conditions recombinant host cells containing the nucleic acid.

Following production by expression a V_H or V_L domain, or specific binding member may be isolated and/or purified using any suitable technique, then used as appropriate.

Antigen-binding fragments, V_H and/or V_L domains and encoding nucleic acid molecules and vectors may be isolated and/or purified from their natural environment, in substantially pure or homogeneous form, or, in the case of nucleic acid, free or substantially free of nucleic acid or genes of origin other than the sequence encoding a polypeptide with the required function.

Systems for cloning and expression of a polypeptide in a variety of different host cells are well known in the art. For cells suitable for producing antibodies, see Gene Expression Systems, Academic Press, eds. Fernandez et al., 1999. Briefly, suitable host cells include bacteria, plant cells, mammalian cells, and yeast and baculovirus systems. Mammalian cell lines available in the art for expression of a heterologous polypeptide include Chinese hamster ovary cells, HeLa cells, baby hamster kidney cells, NSO mouse myeloma cells, and many others. A common bacterial host is E. coli. Any protein expression system compatible with the invention may be used to produce the disclosed antibodies. Suitable expression systems include transgenic animals described in Gene Expression Systems, Academic Press, eds. Fernandez et al., 1999.

Suitable vectors can be chosen or constructed, so that they contain appropriate regulatory sequences, including promoter sequences, terminator sequences, polyadenylation sequences, enhancer sequences, marker genes and other sequences as appropriate. Vectors may be plasmids or viral, e.g., phage, or phagemid, as appropriate. For further details see, for example, Sambrook et al., Molecular Cloning: A Laboratory Manual, 2nd ed., Cold Spring Harbor Laboratory Press, 1989. Many known techniques and protocols for manipulation of nucleic acid, for example, in preparation of nucleic acid constructs, mutagenesis, sequencing, introduction of DNA into cells and gene expression, and analysis of proteins, are described in detail in Current Protocols in Molecular Biology, 2nd Edition, eds. Ausubel et al., John Wiley & Sons, 1992.

A further aspect of the disclosure provides a host cell comprising a nucleic acid as disclosed here. A still further aspect provides a method comprising introducing such nucleic acid into a host cell. The introduction may employ any available technique. For eukaryotic cells, suitable techniques may include calcium phosphate transfection, DEAE-Dextran,

electroporation, liposome-mediated transfection and transduction using retrovirus or other virus, e.g., vaccinia or, for insect cells, baculovirus. For bacterial cells, suitable techniques may include calcium chloride transformation, electroporation and transfection using bacteriophage. The introduction of the nucleic acid into the cells may be followed by causing or allowing expression from the nucleic acid, e.g., by culturing host cells under conditions for expression of the gene.

Methods of Use

The disclosed anti-PD-1 antibodies are capable of negatively regulating PD-1 -associated immune responses. In particular embodiments, the immune response is TcR/CD28-mediated. The disclosed antibodies can act as either agonists or antagonists of PD-1 -associated immune responses, depending on the method of their use. The antibodies can be used to prevent, diagnose, or treat medical disorders in mammals, especially, in humans. Antibodies of the invention can also be used for isolating PD-1 or PD-1 -expressing cells. Furthermore, the antibodies can be used to treat a subject at risk of or susceptible to a disorder or having a disorder associated with aberrant PD-1 expression or function.

Antibodies of the invention can be used in methods for induction of tolerance to a specific antigen (e.g., a therapeutic protein). In one embodiment, tolerance is induced against a specific antigen by co-administration of antigen and an anti-PD-1 antibody of the invention. For example, patients that received Factor VIII frequently generate antibodies to this protein; coadministration of an anti-PD-1 antibody of the invention in combination with recombinant Factor VIII is expected to result in the downregulation of immune responses to this clotting factor.

Antibodies of the invention can be used in circumstances where a reduction in the level of immune response may be desirable, for example, in certain types of allergy or allergic reactions (e.g., by inhibition of IgE production), autoimmune diseases (e.g., rheumatoid arthritis, type I diabetes mellitus, multiple sclerosis, inflammatory bowel disease, Crohn's disease, and systemic lupus erythematosis), tissue, skin and organ transplant rejection, and graft- versus-host disease (GVHD).

When diminished immune response is desirable, the anti-PD- 1 antibodies of the invention may be used as agonists to PD-1 in order to enhance the PD-1 -associated attenuation of the immune response. In these embodiments, co-presentation and physical proximity between positive (i.e., mediated by an antigen receptor, e.g., TcR or BcR) and negative (i.e., PD-1) signals are required. The preferred distance is less than or comparable to the size of a naturally occurring antigen-presenting cell, i.e., less than about 100 μπι; more preferably, less than about 50 μπι; and most preferably, less than about 20 μπι.

In some embodiments, the positive (activating) and the negative (inhibiting) signals are provided by a ligand or antibodies immobilized on solid support matrix, or a carrier. In various embodiments, the solid support matrix may be composed of polymer such as activated agarose, dextran, cellulose, polyvinylidene fluoride (PVDF). Alternatively, the solid support matrix may be based on silica or plastic polymers, e.g., as nylon, dacron, polystyrene, polyacrylates, polyvinyls, teflons, etc.

The matrix can be implanted into the spleen of a patient. Alternatively, the matrix may be used for the ex vivo incubation of T cells obtained from a patient, which are then separated and implanted back into the patient. The matrix may also be made from a biodegradable material such polyglycolic acid, polyhydroxyalkanoate, collagen, or gelatin so that they can be injected into the patient's peritoneal cavity, and dissolve after some time following the injection. The carrier can be shaped to mimic a cell (e.g., bead or microsphere).

In some embodiments, the positive signal is delivered by a T-cell-activating anti-CD3 antibody, which binds TcR. Activating anti-CD3 antibodies are known in the art (see, for example, U.S. Pat. Nos. 6,405,696 and 5,316,763). The ratio between the activating TcR signal and negative PD-1 signal is determined experimentally using conventional procedures known in the art or as described in Examples 8, 9, and 10.

Under certain circumstances, it may be desirable to elicit or enhance a patient's immune response in order to treat an immune disorder or cancer. The disorders being treated or prevented by the disclosed methods include but are not limited to infections with microbes (e.g. bacteria), viruses (e.g., systemic viral infections such as influenza, viral skin diseases such as herpes or shingles), or parasites; and cancer (e.g., melanoma and prostate cancers).

Stimulation of T cell activation with anti-PD-1 antibodies enhances T-T cell responses. In such cases, antibodies act as antagonists of PD-1. Thus, in some embodiments, the antibodies can be used to inhibit or reduce the downregulatory activity associated with PD-1, i.e., the activity associated with downregulation of TcR/CD28-mediated immune response. In these

embodiments, the antibodies are not coupled to a positive signal such as the TcR-mediated stimulation, e.g., the antibodies are in their soluble, support-unbound, form. As demonstrated in the Examples, a blockade of PD-l/PD-L interaction with antagonizing anti-PD-1 antibodies leads to enhanced T cell proliferative responses, consistent with a downregulatory role for the PD-1 pathway in T-T interactions. In various embodiments, the antibodies inhibit binding of PD-L to PD-1 with an IC50 of less than 10 nM, and more preferably less then 5 nM, and most preferably less than 1 nM. Inhibition of PD-L binding can be measured as described in Example 6 or using techniques known in the art.

The antibodies or antibody compositions of the present invention are administered in therapeutically effective amounts. Generally, a therapeutically effective amount may vary with the subject's age, condition, and sex, as well as the severity of the medical condition of the subject. A therapeutically effective amount of antibody ranges from about 0.001 to about 30 mg/kg body weight, preferably from about 0.01 to about 25 mg/kg body weight, from about 0.1 to about 20 mg/kg body weight, or from about 1 to about 10 mg/kg. The dosage may be adjusted, as necessary, to suit observed effects of the treatment. The appropriate dose is chosen based on clinical indications by a treating physician.

The antibodies may given as a bolus dose, to maximize the circulating levels of antibodies for the greatest length of time after the dose. Continuous infusion may also be used after the bolus dose.

Immune cells (e.g., activated T cells, B cells, or monocytes) can also be isolated from a patient and incubated ex vivo with antibodies of the invention. In some embodiments, immune responses can be inhibited by removing immune cells from a subject, contacting the immune cells in vitro with an anti-PD-1 antibody of the invention concomitantly with activation of the immune cells (e.g., by antibodies to the TcR and/or BcR antigen receptor). In such embodiments, the anti-PD-1 antibody should be used in a multivalent form such that PD-1 molecules on the surface of an immune cell become "crosslinked" upon binding to such antibodies. For example, the anti-PD-1 antibodies can be bound to solid support, such as beads, or crosslinked via a secondary antibody. The immune cells may be then isolated using methods known in the art and reimplanted into the patient.

In another aspect, the antibodies of the invention can be used as a targeting agent for delivery of another therapeutic or a cytotoxic agent (e.g., a toxin) to a cell expressing PD-1. The method includes administering an anti-PD-1 antibody coupled to a therapeutic or a cytotoxic agent or under conditions that allow binding of the antibody to PD-1.

The antibodies of the invention may also be used to detect the presence of PD-1 in biological samples. The amount of PD-1 detected may be correlated with the expression level of PD-1, which, in turn, is correlated with the activation status of immune cells (e.g., activated T cells, B cells, and monocytes) in the subject.

Detection methods that employ antibodies are well known in the art and include, for example, ELISA, radioimmunoassay, immunoblot, Western blot, immunofluorescence, immunoprecipitation. The antibodies may be provided in a diagnostic kit that incorporates one or more of these techniques to detect PD-1. Such a kit may contain other components, packaging, instructions, or other material to aid the detection of the protein.

Where the antibodies are intended for diagnostic purposes, it may be desirable to modify them, for example, with a ligand group (such as biotin) or a detectable marker group (such as a fluorescent group, a radioisotope or an enzyme). If desired, the antibodies of the invention may be labeled using conventional techniques. Suitable detectable labels include, for example, fluorophores, chromophores, radioactive atoms, electron-dense reagents, enzymes, and ligands having specific binding partners. Enzymes are typically detected by their activity. For example, horseradish peroxidase can be detected by its ability to convert tetramethylbenzidine (TMB) to a blue pigment, quantifiable with a spectrophotometer. For detection, suitable binding partners include, but are not limited to, biotin and avidin or streptavidin, IgG and protein A, and the numerous receptor-ligand couples known in the art. Other permutations and possibilities will be readily apparent to those of ordinary skill in the art, and are considered as equivalents within the scope of the instant invention.

Antibodies of the invention can be used in screening methods to identify inhibitors of the PD-1 pathway effective as therapeutics. In such a screening assay, a first binding mixture is formed by combining PD-1 and an antibody of the invention; and the amount of binding in the first binding mixture (MO) is measured. A second binding mixture is also formed by combining PD-1, the antibody, and the compound or agent to be screened, and the amount of binding in the second binding mixture (Ml) is measured. A compound to be tested may be another anti-PD-1 antibody, as illustrated in the Examples. The amounts of binding in the first and second binding mixtures are then compared, for example, by calculating the Ml /MO ratio. The compound or agent is considered to be capable of modulating a PD-1 -associated downregulation of immune responses if a decrease in binding in the second binding mixture as compared to the first binding mixture is observed. The formulation and optimization of binding mixtures is within the level of skill in the art, such binding mixtures may also contain buffers and salts necessary to enhance or to optimize binding, and additional control assays may be included in the screening assay of the invention. Compounds found to reduce the PD-1 -antibody binding by at least about 10% (i.e., Ml/M0<0.9), preferably greater than about 30% may thus be identified and then, if desired, secondarily screened for the capacity to ameliorate a disorder in other assays or animal models as described below. The strength of the binding between PD-1 and an antibody can be measured using, for example, an enzyme-linked immunoadsorption assay (ELISA), radio-immunoassay (RIA), surface plasmon resonance-based technology (e.g., Biacore), all of which are techniques well known in the art.

The compound may then be tested in vitro as described in the Examples or in an animal model (see, generally, Immunologic Defects in Laboratory Animals, eds. Gershwin et al., Plenum Press, 1981), for example, such as the following: the SWR X NZB (SNF1) transgenic mouse model (Uner et al. (1998) J. Autoimmune. 11 (3): 233-240), the KRN transgenic mouse (K/BxN) model (Ji et al. (1999) Immunol. Rev. 169: 139); NZB X NZW (B/W) mice, a model for SLE (Riemekasten et al. (2001) Arthritis Rheum., 44(10): 2435-2445); experimental autoimmune encephalitis (EAE) in mouse, a model for multiple sclerosis (Tuohy et al. (1988) J. Immunol. 141: 1126-1130, Sobel et al. (1984) J. Immunol. 132: 2393-2401, and Traugott, Cell Immunol. (1989) 119: 114-129); the NOD mouse model of diabetes (Baxter et al. (1991) Autoimmunity, 9(1): 61-67), etc.).

Preliminary doses as, for example, determined according to animal tests, and the scaling of dosages for human administration is performed according to art-accepted practices. Toxicity and therapeutic efficacy can be determined by standard pharmaceutical procedures in cell cultures or experimental animals. The data obtained from the cell culture assays or animal studies can be used in formulating a range of dosage for use in humans. Therapeutically effective dosages achieved in one animal model can be converted for use in another animal, including humans, using conversion factors known in the art (see, e.g., Freireich et al. (1966) Cancer Chemother. Reports, 50(4): 219-244).

Pharmaceutical Compositions and Methods of Administration

The disclosure provides compositions comprising anti-PD-1 antibodies. Such

compositions may be suitable for pharmaceutical use and administration to patients. The compositions typically comprise one or more antibodies of the present invention and a pharmaceutically acceptable excipient. The phrase "pharmaceutically acceptable excipient" includes any and all solvents, dispersion media, coatings, antibacterial agents and antifungal agents, isotonic agents, and absorption delaying agents, and the like, that are compatible with pharmaceutical administration. The use of such media and agents for pharmaceutically active substances is well known in the art. The compositions may also contain other active compounds providing supplemental, additional, or enhanced therapeutic functions. The pharmaceutical compositions may also be included in a container, pack, or dispenser together with instructions for administration.

A pharmaceutical composition of the invention is formulated to be compatible with its intended route of administration. Methods to accomplish the administration are known to those of ordinary skill in the art. The administration may, for example, be intravenous, intraperitoneal, intramuscular, intracavity, subcutaneous or transdermal. It may also be possible to obtain compositions which may be topically or orally administered, or which may be capable of transmission across mucous membranes. Solutions or suspensions used for intradermal or subcutaneous application typically include one or more of the following components: a sterile diluent such as water for injection, saline solution, fixed oils, polyethylene glycols, glycerin, propylene glycol, or other synthetic solvents; antibacterial agents such as benzyl alcohol or methyl parabens; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates; and agents for the adjustment of tonicity such as sodium chloride or dextrose. The pH can be adjusted with acids or bases, such as hydrochloric acid or sodium hydroxide. Such preparations may be enclosed in ampoules, disposable syringes or multiple dose vials made of glass or plastic.

Pharmaceutical compositions suitable for injection include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersion. For intravenous administration, suitable carriers include physiological saline, bacteriostatic water, Cremophor EL (BASF, Parsippany, N.J.) or phosphate buffered saline (PBS). In all cases, the composition must be sterile and should be fluid to the extent that easy syringability exists. It should be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms such as bacteria and fungi. Prevention of the action of microorganisms can be achieved by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, ascorbic acid, thimerosal, and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars; polyalcohols such as mannitol, sorbitol, and sodium chloride in the composition. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyetheylene glycol, and the like), and suitable mixtures thereof. The proper fluidity 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/or by the use of surfactants. Prolonged absorption of the injectable compositions can be brought about by including in the composition an agent which delays absorption, for example, aluminum monostearate, and gelatin.

Oral compositions generally include an inert diluent or an edible carrier. They can be enclosed in gelatin capsules or compressed into tablets. For oral administration, the antibodies can be combined with excipients and used in the form of tablets, troches, or capsules. Pharmaceutically compatible binding agents, and/or adjuvant materials can be included as part of the composition. The tablets, pills, capsules, troches, and the like can contain any of the following ingredients, or compounds of a similar nature; a binder such as microcrystalline cellulose, gum tragacanth or gelatin; an excipient such as starch or lactose, a disintegrating agent such as alginic acid, Primogel, or corn starch; a lubricant such as magnesium stearate or Sterotes; a glidant such as colloidal silicon dioxide; a sweetening agent such as sucrose or saccharin; or a flavoring agent such as peppermint, methyl salicylate, or orange flavoring.

Systemic administration can also be by transmucosal or transdermal means. For transmucosal or transdermal administration, penetrants appropriate to the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art, and include, for example, detergents, bile salts, and fusidic acid derivatives. Transmucosal administration may be accomplished, for example, through the use of lozenges, nasal sprays, inhalers, or suppositories. For example, in case of antibodies that comprise the Fc portion, compositions may be capable of transmission across mucous membranes in intestine, mouth, or lungs (e.g., via the FcRn receptor- mediated pathway as described in U.S. Pat. No. 6,030,613). For transdermal administration, the active compounds may be formulated into ointments, salves, gels, or creams as generally known in the art. For administration by inhalation, the antibodies may be delivered in the form of an aerosol spray from pressured container or dispenser, which contains a suitable propellant, e.g., a gas such as carbon dioxide, or a nebulizer.

In certain embodiments, the presently disclosed antibodies are prepared with carriers that will protect the compound against rapid elimination from the body, 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. Methods for preparation of such formulations will be apparent to those skilled in the art. Liposomal suspensions containing the presently disclosed antibodies can also be used as pharmaceutically acceptable carriers. These can be prepared according to methods known to those skilled in the art, for example, as described in U.S. Pat. No. 4,522,811.

It may be advantageous to formulate oral or parenteral compositions in a dosage unit form for ease of administration and uniformity of dosage. The term "dosage unit form" as used herein refers to physically discrete units suited as unitary dosages for the subject to be treated; each unit containing a predetermined quantity of active compound calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier.

Toxicity and therapeutic efficacy of the composition of the invention can be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., for determining the LD₅₀ (the dose lethal to 50% of the population) and the ED₅₀ (the dose therapeutically effective in 50% of the population). The dose ratio between toxic and therapeutic effects is the therapeutic index and it can be expressed as the ratio LD₅₀ ED₅₀. Compositions that exhibit large therapeutic indices are preferred.

For any composition used in the present invention, the therapeutically effective dose can be estimated initially from cell culture assays. Examples of suitable bioassays include DNA replication assays, cytokine release assays, transcription-based assays, PD-1/PD-L1 binding assays, creatine kinase assays, assays based on the differentiation of pre-adipocytes, assays based on glucose uptake in adipocytes, immunological assays other assays as, for example, described in the Examples. The data obtained from the cell culture assays and animal studies can be used in formulating a range of dosage for use in humans. A dose may be formulated in animal models to achieve a circulating plasma concentration range that includes the IC₅₀ (i.e., the concentration of the antibody which achieves a half-maximal inhibition of symptoms). Circulating levels in plasma may be measured, for example, by high performance liquid chromatography. The effects of any particular dosage can be monitored by a suitable bioassay. The dosage lies preferably within a range of circulating concentrations with little or no toxicity. The dosage may vary depending upon the dosage form employed and the route of administration utilized.

Kits

The invention provides kits for the treatment or prevention of an immune response. In one embodiment, the kit includes a therapeutic or prophylactic composition containing an effective amount of an inhibitory anti-PDl antibody that disrupts the biological activity of a PDl and/or PD-L1 polynucleotide or polypeptide in unit dosage form. In another embodiment, the kit includes a therapeutic or prophylactic composition containing an effective amount of the anti- PD 1 antibody LOPD 180 in unit dosage form. In some embodiments, the kit comprises a sterile container which contains a therapeutic or prophylactic cellular composition; such containers can be boxes, ampoules, bottles, vials, tubes, bags, pouches, blister-packs, or other suitable container forms known in the art. Such containers can be made of plastic, glass, laminated paper, metal foil, or other materials suitable for holding medicaments.

If desired an antibody or agent of the invention is provided together with instructions for administering the antibody or agent to a subject having or at risk of developing an immune disorder (e.g., a disorder associated with aberrant PD-1 expression or function). The instructions will generally include information about the use of the composition for the treatment or prevention of an immune disorder. In other embodiments, the instructions include at least one of the following: description of the therapeutic agent; dosage schedule and administration for treatment or prevention of an immune disorder or symptoms thereof; precautions; warnings; indications; counter-indications; overdosage information; adverse reactions; animal

pharmacology; clinical studies; and/or references. The instructions may be printed directly on the container (when present), or as a label applied to the container, or as a separate sheet, pamphlet, card, or folder supplied in or with the container.

The practice of the present invention employs, unless otherwise indicated, conventional techniques of molecular biology (including recombinant techniques), microbiology, cell biology, biochemistry and immunology, which are well within the purview of the skilled artisan. Such techniques are explained fully in the literature, such as, "Molecular Cloning: A Laboratory

Manual", second edition (Sambrook, 1989); "Oligonucleotide Synthesis" (Gait, 1984); "Animal Cell Culture" (Freshney, 1987); "Methods in Enzymology" "Handbook of Experimental Immunology" (Weir, 1996); "Gene Transfer Vectors for Mammalian Cells" (Miller and Calos, 1987); "Current Protocols in Molecular Biology" (Ausubel, 1987); "PCR: The Polymerase Chain Reaction", (Mullis, 1994); "Current Protocols in Immunology" (Coligan, 1991). These techniques are applicable to the production of the polynucleotides and polypeptides of the invention, and, as such, may be considered in making and practicing the invention. Particularly useful techniques for particular embodiments will be discussed in the sections that follow.

The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use the anti-PDl antibodies in assay, screening, and therapeutic methods of the invention, and are not intended to limit the scope of what the inventors regard as their invention.

EXAMPLES

Example 1: Identification and Characterization of Anti-PD-1 Antibody, LOPD180

The invention provides the amino acid and nucleic acid sequences of an exemplary anti- PD1 antibody, LOPD180 light chain, heavy chain, light chain variable region, and heavy chain variable region as set forth above.

The identified antibody shows superior binding and inhibitory characteristics relative to other PDl antibodies known in the art, for example relative to the PD-1 35 parent antibody as shown below in Table 1. Characteristics of the PD-1 35 parent antibody are also described in U.S. Pat. No. 7,488,802, which is herein incorporated by reference in its entirety.

PD1/ PD- L2 ligand Inhibition (nM ) Biacore Human PD

Human PD1 Cynomolgous PD1 M ouse PD1 Human PD1 Kd kon k lower 95% upper 95% lower 95% upper 95% lower 95% upper 95% u er 95%

GeoM ean CL CL GeoM ean CL CL n GeoM ean CL CL n GeoM ean lower 95%CL CL _n (nM) ( -1S-1) (

PD1-35 parent 0.838 0.467 1.5 2 1.07 0.306 3.74 2 28.5 1.12 728 2 3.86 1.64 9.08 2 >1000nM

Germ_Lopd180 0.0328 0.000694 1.55 2 0.103 0.0455 0.234 2 4.38 1.28 15 2 0.0657 0.0516 0.0837 2 25 5.6E+05 1.4

Other Embodiments

From the foregoing description, it will be apparent that variations and modifications may be made to the invention described herein to adopt it to various usages and conditions. Such embodiments are also within the scope of the following claims.

The recitation of a listing of elements in any definition of a variable herein includes definitions of that variable as any single element or combination (or subcombination) of listed elements. The recitation of an embodiment herein includes that embodiment as any single embodiment or in combination with any other embodiments or portions thereof.

All patents, publications, and accession numbers mentioned in this specification are herein incorporated by reference to the same extent as if each independent patent, publication, and accession number was specifically and individually indicated to be incorporated by reference.

Claims

WHAT IS CLAIMED IS:

1. An isolated antibody or antigen-binding fragment thereof that specifically binds to a PD-1 polypeptide and comprises a VH and/or a VL domain, where the VH and/or VL domain are each identical to or each have at least 90%, 95%, or 98% identity to the VH and VL amino acid sequences of SEQ ID NOs: 7 and 9.

2. An isolated antibody or antigen-binding fragment thereof comprising: a V_H domain of LOPD180 corresponding to SEQ ID NO: 7.

3. An isolated antibody or antigen-binding fragment thereof comprising: a V_L domain of LOPD180 corresponding to SEQ ID NO: 9.

4. An isolated antibody or antigen-binding fragment thereof comprising: a V_H domain of LOPD 180 corresponding to SEQ ID NO: 7 and aV_L domain of LOPD 180 corresponding to SEQ ID NO: 9.

5. An isolated antibody or antigen-binding fragment thereof comprising: a V_H domain or an antigen-binding fragment thereof that comprises 3 CDRs of LOPD 180; and a V_L domain or an antigen-binding fragment thereof that comprises 3 CDRs of LOPD 180.

6. An isolated antibody or antigen-binding fragment thereof that consists essentially of LOPD 180.

7. The isolated antibody or antigen-binding fragment thereof of any one of claims 1-6 that specifically binds an epitope within the extracellular domain of human or mouse PD-1.

8. The isolated antibody or antigen-binding fragment thereof of any one of claims 1-6, wherein the antibody is an antigen binding fragment Fab, F(ab')₂, Fv, scFv, Fd or dAb.

9. The isolated antibody or antigen-binding fragment thereof of any one of claims 1-8, wherein the antibody specifically binds to the extracellular domain of PD-1 with an affinity constant greater than 10⁷ M^_1.

10. The isolated antibody or antigen-binding fragment thereof of any one of claims 1-8, where the antibody inhibits the binding of PD-L1 or PD-L2 to PD-1 with an IC₅o of less than ΙΟηΜ.

11. The isolated antibody or antigen-binding fragment thereof of any one of claims 1-10, wherein the antibody is a human antibody.

12. The isolated antibody or antigen-binding fragment thereof of any one of claims 1-11, wherein the antibody is IgGi or IgG₄.

13. The isolated antibody or antigen-binding fragment thereof of any one of claims 1-12, wherein the antibody is IgG^or IgGi_K.

14. The isolated antibody or antigen-binding fragment thereof of any one of claims 1-13, wherein the VH domain comprises HI, H2 and H3 regions, where HI corresponds to amino acids 31-37 of SEQ ID NO: 7, where H2 corresponds to amino acids 52-67 of SEQ ID NO: 7, and where H3 corresponds to amino acids 110-116 of SEQ ID NO: 7 and/or the VL domain comprises LI, L2 and L3 regions, where LI corresponds to amino acids 23-35 of SEQ ID NO: 9, where L2 corresponds to amino acids 51-57 of SEQ ID NO: 9, and where L3 corresponds to amino acids 90-100 of SEQ ID NO: 9.

15. A pharmaceutical composition comprising the isolated antibody or antigen-binding fragment thereof of any one of claims 1-14.

16. A kit comprising the isolated antibody of any of claims 1-14, and directions for the use of the antibody in an immunological assay.