Recombinant antibodies against programmed death 1 (PD-1) and uses thereof

Description

Technical Field

[0001] The present invention relates to antibodies that bind to programmed cell death 1 (PD-1) and particularly therapeutic and diagnostic methods of using those antibodies. The present invention belongs to the field of biotechnology.Background Art

[0002] In general, a need exists to provide safe and effective therapeutic methods 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.

[0003] 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.

[0004] 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.

[0005] 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.

[0006] 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 or CD279) is an inhibitory receptor and a counterpart of CTLA-4. This disclosure relates to modulation of immune responses mediated by the PD-1 receptor.

[0007] 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 activated 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).

[0008] 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 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.

[0009] Experimental data implicates the interactions of PD-1 with its ligands in down regulation 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.

[0010] Since PD-1 plays an important role in autoimmunity, tumor immunity and infectious immunity, it is an ideal target for immunotherapy. Blocking PD-1 with antagonists, including monoclonal antibodies, has been studied in treatments of cancer and chronic viral infections (Sheridan 2012, Nature Biotechnology 30: 729-730). Monoclonal antibodies to PD-1 are known in the art and have been described, for example, in US Patent / Publication Nos. US8008449, US8779105, US9084776, US9358289, US9387247, US20090217401, US20130133091 ,US20140212422, US20140294852, US20140328833, US20140348743, US20150165025, US2016108123 and WO Patent / Publication Nos. WO2006121 168, WO20091 154335, WO2012145493, WO2013014668, WO200910161 1 , EP2262837, WO2016106159 EP2504028.Summary of Invention

[0011] The present invention relates to an anti-PD-1 antibody, or antigen binding fragment thereof, which specifically binds to PD-1 and comprises a VH region amino acid sequence comprising SEQ ID NO 74 and a VL region amino acid sequence comprising SEQ ID NO 76.Description of Embodiments

[0012] According to one embodiment, it is provided the use of the anti-PD-1 antibody, or antigen binding fragment thereof, according to the preceding paragraph for the detection of PD-1 in vitro or as diagnostic agent in vitro.

[0013] According to embodiments, the anti-PD-1 antibody is provided for use in treating a cancer, preferably a breast cancer, lung cancer, stomach cancer, colon cancer, kidney cancer or melanoma, or an infectious disease in a subject.

[0014] In a further preferred embodiments, the present invention provides humanized antibodies or fragments which comprise a heavy chain variable region (H-CVR) further containing human IgG1, IgG2, IgG3, IgG4 and / or a heavy chain FR region variant.

[0015] In a preferred embodiment, the antibodies or fragments comprise a light chain variable region (L-CVR) further containing human k , λ chain or a light chain FR region variant.

[0016] In a further preferred embodiments, the present invention provides humanized antibodies or fragments which further contain human IgG and / or a light chain constant region variant.

[0017] In a preferred embodiments, the anti-PD-1 antibodies or antigen-binding fragments comprise human IgG1, IgG2, IgG3, IgG4 and / or a heavy chain constant variant, preferred human IgG1 or IgG4.

[0018] In some embodiments, the anti-PD-1 antibody or fragment, consists of Fab, Fv, single chain variable fragment (scFv), F(ab') 2 and diabody.

[0019] In another aspect, disclosed are isolated nucleic acids, that encode the antibodies described herein.

[0020] In another aspect, antibody or antigen binding portion of the invention can be derivatized or linked to another functional molecule, e.g., another peptide or protein (e.g., another antibody or ligand receptor) to generate at least two different the bispecific binding sites or target molecules. Antibodies of the invention can in fact be derivatized or linked to more than one other functional molecule to generate more than two different binding sites and / or target molecule binding multispecific molecule; such multispecific molecules are also intended to be as used herein.

[0021] Also disclosed is an expression vector comprising the nucleic acids encoding the claimed antibody.

[0022] Also disclosed is a host cell transfected with said expression vector.

[0023] The host cell is selected from mammalian cells, more specifically, the mammalian cell is selected from Chinese hamster ovary cells.Examples

[0024] The following examples are provided to further explain and demonstrate some of the presently preferred embodiments and are not intended to limit the scope or content of the invention in any way.Example-1: Generation of rabbit anti-PD-1 Antibodies A. Immunization of rabbit with PD-1

[0025] Four female rabbits aged 4 months were used for immunizations. The each rabbit was subcutaneously primed with 50 µg of own-made recombinant human PD-1 mixed well with complete Freund's adjuvant (Sigma-Aldrich,Cat#263810). Two to three weeks later, the rabbits were boosted with 25 µg of soluble PD-1 with incomplete Freund's adjuvant (Sigma- Aldrich, Cat#263910). The immune response was monitored by checked antiserum taken from rabbit's auricular vein blood. A serial dilutions of the antiserum from immunized animals were then screened for binding to the coated human PD-1 by ELISA. The same purified protein in PBS used for immunizations diluted to 1µg / ml, was coated overnight microtiter plate (Nunc MAXISORP), 100µl / well, incubated at 4°C overnight, then blocked with 200µl / well containing 5% fetal calf serum, PBS solution of 0.05% Tween 20. A serially diluted immunized sera were added to each well and incubated at room temperature for 1 hour. With PBS / Tween 20 solution washing the plate, horseradish peroxidase-conjugated goat anti-rabbit IgG antibody (Jackson Immunoresearch Labs, Cat #:111-035-046) was incubated for 1 hour at room temperature. After the plate was washed with washing buffer, 100pl / well of TMB substrate was added, then (Pierce, Cat # 34021) colored, stopped reaction and measured OD value at 450 nm.B. Screening of rabbit anti-PD-1 Antibodies for Binding to Human PD-1

[0026] According to titer comparison, the rabbits with anti-PD-1 high titer immunoglobulin were chosen for isolation of rabbit PD-1-specific B cell. Cells were interrogated for antigen-specific B cells, unstimulated or stimulated, using LPS (Invivogen) at a concentration of 20 ng / mL. The cells, unstimulated or stimulated, were then loaded into pre-coated and blocked plate as described below. 384 well plate coated with anti-rabbit IgG antibody (Jackson Immunoresearch, Cat #111-005-008) was blocked with PBS solution containing 5% fetal calf serum and 0.05% Tween 20, then used to capture the antigen-specific B cells, contained the secreted output of the B cells. The antibodies secreted by the B cells in each well were then assayed for reactivity against human PD-1, or an unrelated antigen, and also assayed for IgG reactivity. Mainly, following three combined approaches were further applied for efficiently screened rabbit anti-PD-1 antibodies with blocking function and high binding affinity.(i) Screening of functional anti-PD-1 antibody by Fluorometric Microvolume Assay Technology, FMAT

[0027] Recombinant antibodies from cultured supernatants were also used in cell-based binding studies. HEK293 cells were transfected with expression plasmids encoding the Ig heavy and light chains of rabbit anti-PD-1 antibodies. After 3-5 days, recombinant antibodies in the supernatants of transfected cells were harvested. Stable HEK293 cells expressing human PD-1 or primary cells were used for the cell-based binding confirmation studies. Antibodies from cultured supernatants were assessed for binding to cell surface PD-1 using fluorescently labeled anti-rabbit IgG antibody (Jackson Immunoresearch, Cat #111-095-046). Fluorescence microscopy studies revealed that a number of anti-PD-1 antibodies obtained from transfection supernatants bound to PD-1 expressed on the surface of HEK293 cells. In this screening assay, own-made anti-PD-1 antibody and isotype control rabbit IgG were used as controls. The fig.1A represents one of multiple 384-well plates detecting PD-1 antibodies from immunized rabbits that inhibit PD-1 function. Antibodies which show no inhibition are seen as signals above the plane of the graph. Antibodies that inhibit PD-1 function remain "flat" with the plane of the graph and represent the majority in FMAT screens. Fig.1B further summarize results of tests of binding of various rabbit anti-PD-1 antibodies to PD-1 expressed on the surface of HEK293 cells. Four antibodies with desired inhibition function and biding affinity were selected and confirmed by other assays below.(ii) Screening of binding anti-PD-1 antibody by Enzyme-Linked Immunosorbent Assay, ELISA

[0028] To begin the ELISA, 384-well plates were coated with human PD-1, blocked with assay diluent buffer, and washed, prior to incubation with serial dilutions of supernatants from the cultured PD-1-specific B-cells. The samples were incubated for one hour, and then the ELISA plates were washed. The detection goat anti-rabbit antibody-conjugated with HRP in the same assay diluent buffer, was then added, the assay plate was washed, and substrate solution was added to the wells in the assay plate. After the enzyme reaction was stopped, colorimetric density at 450 nm was measured in a conventional plate reader. Over hundred of PD-1-positive clones were screened by ELISA. Furthermore, the four of rabbit anti-PD-1 antibodies with specifically and strongly binding activity, named as Abs-r-923, Abs-r-924, Abs-r-925 and Abs-r-926 were defined and selected for characterizations (See in Fig.1C). Binding data showed that they did not react with other unrelated proteins as coated, but also did not have cross-reactivity with mouse PD-1.(iii) The interaction of PD-1 with PD-L1 blocked by selected anti-PD-1 antibody (See Example 3 below).C. Isolation of PD-1 Antibodies that bind to Human PD-1

[0029] Antibody-producing cells identified from screening above were used for isolated the genetic sequences encoding antibody heavy and light chains The genes encoding the specific antibodies that recognize human PD-1 were retrieved using RT-PCR. Retrieved cells were placed into reverse transcription buffer, and the mRNA from each individual cell was reverse transcribed into cDNA. After generating these amplicons by standard nested polymerase chain reaction (PCR), these amplicons were subjected to direct sequencing. These DNA sequences were then bioinformatically filtered for sequence quality and organized into a sequence database for cladistics analysis, in order to identify how many unique antibody clades were isolated that recognize PD-1. According to the manufacturer's protocol, the amplified and selected sequences were cloned into HEK293 expression system for producing PD-1 antibody. Complete antibody variable regions comprising a pair of heavy (V H ) and light chain variable regions (V L ) were reformatted into plasmids with the proper elements for transient expression in mammalian cell lines, e.g., HEK293 using standard molecular biology techniques. For example, the variable heavy (SEQ ID NO:54) and variable light (SEQ ID NO:56) cDNA sequences were sub-cloned into the vector backbone. Supernatants from transiently transfected mammalian cell lines were used to test for antibody expression, specificity and affinity. Various V H and V L were paired to yield more than hundred of clones, in which 10 (a to j clones) of them were selected and expressed in HEK293 cells and assayed for PD-1 functional inhibition assay (See Fig.1C). These analyses identified unique clades of sequences that recognize human PD-1. Selected sequences were sub-cloned into PCR 2.1 (LifeTech) for further propagation.

[0030] The sequences of the individual heavy chain and light chain variable regions are shown in Figs. 3A, 4A, 5A and 6A (HCVR) and Figs. 3B, 4B, 5B and 6B (LCVR). The complementarity determining regions (CDRs) and framework regions (FRs) are indicated as well. Tables 1, 2, 5, 6, 9,10,13 and 14 list each H-CDR or L-CDR by clone name and corresponding sequence identifier, Abs-r-923, Abs-r-924, Abs-r-925 and Abs-r-926. They are also described in PD-1 antibody sequence listing.

[0031] Fig.1D also showed that an example of an ELISA-based binding assay. The results represent an average of two experiments. According to PD-1 antibody ability to block the binding of PD-L1, Abs-r-923, Abs-r-924, Abs-r-925 and Abs-r-926 clones are selected as a candidates for further development of a humanized antibody (See also in Example 2 below).Example-2. Humanization of Rabbit Anti-PD-1 Antibodies

[0032] Humanization of selected rabbit anti-PD-1 antibodies was performed in order to reduce the apparent immunogenicity of the rabbit-based antibodies. Using antibody engineering information well-known in the art, and conventional bioinformatics tools, amino acid sequences of certain rabbit anti-PD-1 antibodies were analyzed and compared against known human antibody sequences. Based on these analyses and comparisons, certain human sequences were chosen for conventional rabbit CDR grafting, and inclusion of suitable back mutations. In tests for binding to human PD-1, these humanized antibodies were evaluated with respect to criteria such as function, affinity, avidity, binding kinetics, and biochemical behavior such as aggregation as well as expression levels.A. Humanized heavy chain variable region sequence

[0033] With the known human germline immunoglobulin heavy chain sequences are compared, selected low immunogenicity human germline framework sequence to finalize humanization of four rabbit PD-1 antibodies, Abs-r-923, Abs-r-924, Abs-r-925 and Abs-r-926. The DNA and amino acid sequences of the four rabbit recombinant monoclonal antibodies are shown in Figs. 3A, 4A, 5A and 6A, and also in SEQ ID NOs: 49, 50, 53, 54, 57, 58, 61 and 62, as well as further H-CDRs in Tables 1, 5, 9 and 13 below. See these sequences also in PD-1 antibody sequence listing.

[0034] The DNA and amino acid sequences of the heavy chain variable region of humanized Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 are shown in SEQ ID NOs: 65, 66, 69, 70, 73, 74, 77 and 78, and further H-CDR sequences in Tables 3, 7,11 and 15. See these sequences also in PD-1 antibody sequence listing.B. Humanized light chain variable region sequence

[0035] With the known human germline immunoglobulin light chain sequences are compared, selected low immunogenicity human germline framework sequence to finalize humanization of four rabbit PD-1 antibodies, Abs-r-923, Abs-r-924, Abs-r-925 and Abs-r-926. The DNA and amino acid sequence of the light chain variable region of the four rabbit recombinant monoclonal antibodies are shown in Figs. 3B, 4B, 5B and 6B, and also in SEQ ID NOs: 51, 52, 55, 56, 59, 60, 63 and 64, and further L-CDRs in Tables 2, 6,10 and 14. See these sequences also in PD-1 antibody sequence listing.

[0036] The DNA and amino acid sequence of the light chain variable region of humanized Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 are shown in SEQ ID NOs: 67, 68, 71, 72, 75, 76, 79 and 80, and further L-CDRs in Tables 4, 8, 12 and 16. See these sequences also in PD-1 antibody sequence listing.Example-3: Blocking of humanized PD-1 antibodies binding to PD-L1

[0037] 100 µl of unlabeled human PD-L1 (R & D Systems, Cat# 156-B7-100) was coated at a concentration of 1 µg / mL in PBS on a 96-well microtiter plates overnight at 4°C. Nonspecific binding sites were subsequently blocked using a 0.5% (w / v) solution of BSA and 0.05% (w / v) Tween 20 in PBS. In a blocking assay, a constant concentration of 1.5nM (0.5ug / ml) of human PD-1 protein was added to a serial dilutions of humanized anti-PD-1 antibodies or Nivolumab or isotype control antibody. The antibody-protein complexes with 1.5 nM constant human PD-1 were transferred to microtiter plates coated with human PD-L1. After incubating for 1 hour at RT, the wells were washed, and plate-bound human PD-1 was detected with an anti-human IgG Fc antibody conjugated with horseradish peroxidase (HRP) (Abcam, Cat#ab97225). After the plate was washed with washing buffer, 100 µl / well of TMB substrate was added, then colored, stopped reaction and measured OD value at 450 nm. As shown in Fig.2, the humanized anti-PD-1 antibodies, Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 still maintained their functions and specifically blocked the binding of PD-1 to its ligand PD-L1, and significantly better than the blocking effect of Nivolumab.Example 4. Construction and expression of a fully humanized PD-1 antibody

[0038] Human IgG4 heavy chain constant region fragment IgG4 Fc sequence and κ light chain constant region fragment sequences were synthesized by the company IDT (Integrated DNA Technologies, Coralville, Iowa) respectively, then put to pcDNA3 vector backbone to pBA-H4 and pBA-Ck, pBA-H4 (containing human IgG4 heavy chain constant region IgG4Fc) and pBA-Ck (containing the human κ light chain constant region fragment) vector built by Bioabs company, using the CMV promoter pBA-H4 in VH and CH, puromycin resistance gene use PGK promoter, in pBA-Ck in VL use CMV promoter, neomycin resistance gene SV40 promoter. According to the protein sequence of the antibody heavy chain variable region sequence and light chain variable region encoding the heavy chain and light design chain variable region DNA sequences, and in accordance with optimizing expression in CHO cells, and further optimize the DNA sequences encoding the heavy and light chain variable region, wherein the encoding of the present invention is the humanized anti-PD-1 antibody heavy chain variable region DNA sequences are shown in SEQ ID NOs: 73 (Abs-h-925) the present invention encoding the humanized anti-PD-1 antibody light chain variable region DNA sequence as SEQ ID NOs: 75 (Abs-h-925) and. All tested PD-1 antibodies were purified by protein A column containing suitable resin, MabSelect ™< from GE Healthcare.Example 5. Specificity and affinity of humanized PD-1Antibodies

[0039] The binding affnity of the anti-PD-1 antibodies Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 were determined by surface plasmon resonance (SPR) using the Biacore ™< technology. This technology allows the label-free determination of the microscopic rate constants for binding (k a ) and dissociation (k d ) of a ligand to a receptor. It is therefore especially suited for characterizing the antibody-antigen interactions. Indirect binding of antibodies to the Biacore ™< chip surface was done via an anti-human IgG antibody (GE Healthcare Bio-Sciences AB; Cat# BR-1008-39) 25 pg / ml in immobilization buffer (10mM Sodium acetate pH 5.0). Anti-PD-1 antibody in 2-fold increasing concentrations from 0.14 to 7.68 nM was diluted into assay buffer to measure affinity of Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926. The kinetic traces were evaluated with the Biacore ™< T2000. The full set of these traces with increasing concentrations is taken together and is called a run. Two zero concentration samples (blank runs) were included in each analyte concentration series to allow double-referencing during data evaluation. The kinetic rate constants for association (k a ) and dissociation (k d ) as well as the dissociation equilibrium constant (K D ) were calculated. The affinity data of Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 are shown in Table 17.Example 6. Competitive Binding of Humanized PD-1 Antibodies with Nivolumab

[0040] Competitive binding analysis was performed on humanized antibodies, Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 with Nivolumab, using ELISA-based assay. The assay was conducted essentially as follows. A different of concentration of PD-1 antibodies, Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 were pre-incubated with constant concentration, 50 ng / ml of Nivolumab or an isotype antibody (negative control) for 1 hour at 37°C. The mixtures were added into 96-well plate coated human PD-1 at concentration of 100 ng / well and further incubated for other hour, then washed. HRP-conjugated anti-human antibody was added and incubated. After the plate was washed with washing buffer, 100µl / well of TMB substrate was added, then (Pierce, Cat # 34021,) colored, stopped reaction and measured OD value at 450 nm.

[0041] All humanized antibodies competitively inhibited the binding of Nivolumab to PD-1. However, antibody Abs-h-923 performed weak competition binding to PD-1. Antibody Abs-h-926 had the highest competition activity compared to the other three. In contrast, isotype antibody did not competitively inhibit binding of Nivolumab to PD-1 at all. Representative results are shown in Fig.7.

[0042] The EC 50 of Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 is estimated by determining concentration of Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 that exhibit roughly one-half maximal absorbance from the point at which the Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 display saturation behavior (See Table 18).Example 7. Humanized PD-1 Antibodies induced IL-2 Cytokine Secretion in MLR Assays

[0043] increased secretion of IL-2 cytokine was observed in response to four antibodies Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 in mixed lymphocyte reaction (MLR) assays. One commercial stage anti-PD-1 antibody, Nivolumab was used as benchmarks for this experiment. The MLR assay was performed using commercially available monocyte-derived dendritic cells as stimulator cells and purified CD4 +< T lymphocytes as responder cells from a different healthy blood donor. Supernatants were collected at 2.5 days after beginning the assay. Cytokine secretion was measured in a capture sandwich immunoassay using MagPlex ®< microspheres (Luminex), according to the vendor's instructions.

[0044] Fig.8 summarized the results of an MLR assay performed on human PBMCs treated with the anti-PD-1 antibodies. The data indicated that treatment with humanized PD-1 antibodies, Abs-h-924, Abs-h-925 and Abs-h-926 resulted in significantly increased secretion of cytokine IL-2, in comparison with antibody Nivolumab or the IgG4 isotype control (Biolegend). Interestedly, antibody Abs-h-923 showed weaker induced IL-2 response than other three antibodies Abs-h-924, Abs-h-925 and Abs-h-926. [Table 1]Table 1. A H-CDR and full heavy chain variable sequences of rabbit anti-PD-1 antibody Abs-r-923 No Heavy Chain domain & Full Heavy Chain Sequence & Note Sequence Code IH-CDR1GFTLSSYASEQ ID NO: 1IIH-CDR2SNAGNGNTSEQ ID NO: 2IIIH-CDR3YWYFDLSEQ ID NO: 3VIDNASee sequence listing and Fig.3ASEQ ID NO: 49VProteinThe same aboveSEQ ID NO: 50 [Table 2] Table 2. A L-CDR and full light chain variable sequences of rabbit anti-PD-1 antibody Abs-r-923 No Light Chain Domain & Full Light Chain Sequence & Note Sequence Code IL-CDR1QSGSSFSEQ ID NO: 13IIL-CDR2ANNKRESEQ ID NO: 14IIIL-CDR3GTYTDSPPTSEQ ID NO: 15VIDNASee sequence listing and Fig.3BSEQ ID NO: 51VProteinThe same aboveSEQ ID NO: 52 [Table 3] Table-3. A H-CDR and full heavy chain variable sequence of humanized anti-PD-1 antibody Abs-h-923 No Heavy Chain domain & Full Heavy Chain Sequence & Note Sequence Code IH-CDR1GYTFTSYASEQ ID NO: 25IIH-CDR2SNAGNGNTSEQ ID NO: 26IIIH-CDR3YWYFDLSEQ ID NO: 27VIDNASee sequence listing and Fig.3CSEQ ID NO: 65VProteinThe same aboveSEQ ID NO: 66 [Table 4] Table 4. A L-CDR and full light chain variable sequence of humanized anti-PD-1 antibody Abs-h-923 No Light Chain Domain & Full Light Chain Sequence & Note Sequence Code IL-CDR1QSGSSFSEQ ID NO: 37IIL-CDR2ANNKRESEQ ID NO: 38IIIL-CDR3GTYTDSPPTSEQ ID NO: 39VIDNASee sequence listing and Fig.3DSEQ ID NO: 67VProteinThe same aboveSEQ ID NO: 68 [Table 5] Table 5. A H-CDR and full heavy chain variable sequences of rabbit anti-PD-1 antibody Abs-r-924 No Heavy Chain domain & Full Heavy Chain Sequence & Note Sequence Code IH-CDR1GFSISSYGSEQ ID NO: 4IIH-CDR2ISYDGSNKSEQ ID NO: 5IIIH-CDR3YYYYYGMDVSEQ ID NO: 6VIDNASee sequence listing and Fig.4ASEQ ID NO: 53VProteinThe same aboveSEQ ID NO: 54 [Table 6] Table 6. A L-CDR and full light chain variable sequences of rabbit anti-PD-1 antibody Abs-r-924 No Light Chain Domain & Full Light Chain Sequence & Note Sequence Code IL-CDR1QSLSSYSEQ ID NO: 16IIL-CDR2DVSNRASEQ ID NO: 17IIIL-CDR3QQRTNWPRASEQ ID NO: 18VIDNASee sequence listing and Fig.4BSEQ ID NO: 55VProteinThe same aboveSEQ ID NO: 56 [Table 7] Table-7. A H-CDR and full heavy chain variable sequence of humanized anti-PD-1 antibody Abs-h-924 No Heavy Chain domain & Full Heavy Chain Sequence & Note Sequence Code IH-CDR1GFTFSSYGSEQ ID NO: 28IIH-CDR2ISYDGSNKSEQ ID NO: 29IIIH-CDR3YYYYYGMDVSEQ ID NO: 30VIDNASee sequence listing and Fig.4CSEQ ID NO: 69VProteinThe same aboveSEQ ID NO: 70 [Table 8] Table 8. A L-CDR and full light chain variable sequence of humanized anti-PD-1 antibody Abs-h-924 No Light Chain Domain & Full Light Chain Sequence & Note Sequence Code IL-CDR1QSLSSYSEQ ID NO: 40IIL-CDR2DVSNRASEQ ID NO: 41IIIL-CDR3QQRTNWPRASEQ ID NO: 42VIDNASee sequence listing and Fig.4DSEQ ID NO: 71VProteinThe same aboveSEQ ID NO: 72 [Table 9] Table 9. A H-CDR and full heavy chain variable sequences of rabbit anti-PD-1 antibody Abs-r-925 No Heavy Chain domain & Full Heavy Chain Sequence & Note Sequence Code IH-CDR1GFTLSSYASEQ ID NO: 7IIH-CDR2ISYDGSNKSEQ ID NO: 8IIIH-CDR3YYYYYYMDVSEQ ID NO: 9VIDNASee sequence listing and Fig.5ASEQ ID NO: 57VProteinThe same aboveSEQ ID NO: 58 [Table 10] Table-10. A L-CDR and full light chain variable sequences of rabbit anti-PD-1 antibody Abs-r-925 No Light Chain Domain & Full Light Chain Sequence & Note Sequence Code IL-CDR1QSVSSYSEQ ID NO: 19IIL-CDR2EASNRASEQ ID NO: 20IIIL-CDR3QQRTNWPPASEQ ID NO: 21VIDNASee sequence listing and Fig.5BSEQ ID NO: 59VProteinThe same aboveSEQ ID NO: 60 [Table 11] Table 11. A H-CDR and full heavy chain variable sequence of humanized anti-PD-1 antibody Abs-h-925 No Heavy Chain domain & Full Heavy Chain Sequence & Note Sequence Code IH-CDR1AFTFSSYASEQ ID NO: 31IIH-CDR2ISYDGSNKSEQ ID NO: 32IIIH-CDR3YYYYYYMDVSEQ ID NO: 33VIDNASee sequence listing and Fig.5CSEQ ID NO: 73VProteinThe same aboveSEQ ID NO: 74 [Table 12] Table 12. A L-CDR and full light chain variable sequence of humanized anti-PD-1 antibody Abs-h-925 No Light Chain Domain & Full Light Chain Sequence & Note Sequence Code IL-CDR1QSVSSYSEQ ID NO: 43IIL-CDR2EASNRASEQ ID NO: 44IIIL-CDR3QQRTNWPPASEQ ID NO: 45VIDNASee sequence listing and Fig.5DSEQ ID NO: 75VProteinThe same aboveSEQ ID NO: 76 [Table 13] Table 13. A H-CDR and full heavy chain variable sequences of rabbit anti-PD-1 antibody Abs-r-926 No Heavy Chain domain & Full Heavy Chain Sequence & Note Sequence Code IH-CDR1GISLSSYYSEQ ID NO: 10IIH-CDR2IYYSGSTNSEQ ID NO: 11IIIH-CDR3WYFDLSEQ ID NO: 12VIDNASee sequence listing and Fig.6ASEQ ID NO: 61VProteinThe same aboveSEQ ID NO: 62 [Table 14] Table 14. A L-CDR and full light chain variable sequences of rabbit anti-PD-1 antibody Abs-r-926 No Light Chain Domain & Full Light Chain Sequence & Note Sequence Code IL-CDR1NSVSSSSEQ ID NO: 22IIL-CDR2DTSNRESEQ ID NO: 23IIIL-CDR3QQRDNWPRASEQ ID NO: 24VIDNASee sequence listing and Fig.6BSEQ ID NO: 63VProteinThe same aboveSEQ ID NO: 64 [Table 15] Table 15. A H-CDR and full heavy chain variable sequence of humanized anti-PD-1 antibody Abs-h-926 No Heavy Chain domain & Full Heavy Chain Sequence & Note Sequence Code IH-CDR1GGSISSYYSEQ ID NO: 34IIH-CDR2IYYSGSTNSEQ ID NO: 35IIIH-CDR3WYFDLSEQ ID NO: 36VIDNASee sequence listing and Fig.6CSEQ ID NO: 77VProteinThe same aboveSEQ ID NO: 78 [Table 16] Table 16. A L-CDR and full light chain variable sequence of humanized anti-PD-1 antibody Abs-h-926 No Light Chain Domain & Full Light Chain Sequence & Note Sequence Code IL-CDR1NSVSSSSEQ ID NO: 46IIL-CDR2DTSNRESEQ ID NO: 47IIIL-CDR3QQRDNWPRASEQ ID NO: 48VIDNASee sequence listing and Fig.6DSEQ ID NO: 79VProteinThe same aboveSEQ ID NO: 80 [Table 18] Table 18. EC50 of humanized antibodies bindingAntibodyEC50 (nM)Abs-h-9230.41Abs-h-9240.14Abs-h-9250.15Abs-h-9260.18 Reference to Deposited Biological Material

[0045] Not apply in this application.Sequence Listing Free Text

[0046] SEE PD-1 ANTIBODY SEQUENCE LISTING FILEPatent Literature

[0047] PTL1: WO2013173223A1 PTL2: WO2015036394A1, PTL3: WO2015112800A1, PTL4: WO2015112900A1, PTL5: WO2016020856A3, PTL6: WO2016068801A1 PTL7: WO2016077397A3 PTL8: WO2016106159A1 PTL9: US 8735553 B1 Non Patent Literature

[0048] NPL1: Sharma P, Allison JP. immune checkpoint targeting in cancer therapy: toward combination strategies with curative potential. Cell. 2015;161(2):205-14. NPL2: Webster RM. The immune checkpoint inhibitors: where are we now? Nat Rev Drug Discov. 2014;13(12):883-4. NPL3: Garon EB, Rizvi NA, Hui R, Leighl N, Balmanoukian AS, Eder JP, et al. Pembrolizumab for the treatment of non-small-cell lung cancer. N Engl J Med. 2015;372(21):2018-28 NPL4:Benson Jr DM, Bakan CE, Mishra A, Hofmeister CC, Efebera Y, Becknell B, et al. The PD-1 / PD-L1 axis modulates the natural killer cell versus multiple myeloma effect: a therapeutic target for CT-011, a novel monoclonal anti- PD-1 antibody. Blood. 2010;116(13):2286-94. NPL5:Brahmer J, Reckamp KL, Baas P, Crino L, Eberhardt WE, Poddubskaya E, et al. Nivolumab versus docetaxel in advanced squamous-cell non-small-cell lung cancer. N Engl J Med. 2015;373(2):123-35. Brief Description of Drawings

[0049] Fig.1A [fig.1A] shows summarizing data on specific and high-affinity binding of selected rabbit anti-human-PD-1 recombinant antibodies by FMAT assay. Fig.1B [fig.1B] shows summarizing data on both PD-1 inhibition function and binding affinity of selected rabbit anti-human-PD-1 recombinant antibodies, Abs-r-923, Abs-r-924, Abs-r-925 and Abs-r-926. Fig.1C [fig.1C] shows summarizing data on binding specificity of selected rabbit anti-human-PD-1 recombinant antibodies, Abs-r-923, Abs-r-924, Abs-r-925 and Abs-r-926 by ELISA. Fig.1D [fig.1D] shows summarizing data on inhibition activity of selected ten rabbit anti-human-PD-1 recombinant antibodies and picked four of them for humanization, Abs-r-923, Abs-r-924, Abs-r-925 and Abs-r-926. Fig.2 [fig.2] shows summarizing data on PD-1 binding to PD-L1 inhibited by four humanized anti-human-PD-1 recombinant antibodies, Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926. Fig.3A [fig.3A] shows DNA sequence (SEQ ID NO:49) and amino acid sequence (SEQ ID NO:50) of Heavy Chain Variable Regions (H-CVR) from rabbit anti-human-PD-1 recombinant antibody, Abs-r-923. Complementarity determining regions of H-CDR1 through H-CDR3 are also shown in Table 1. Fig.3B [fig.3B] shows DNA sequence (SEQ ID NO:51) and amino acid sequence (SEQ ID NO:52) of Light Chain Variable Regions (L-CVR) from rabbit anti-human-PD-1 recombinant antibody, Abs-r-923. Complementarity determining regions of L-CDR1 through L-CDR3 are also shown in Table 2. Fig.3C [fig.3C] shows DNA sequence (SEQ ID NO:65) and amino acid sequence (SEQ ID NO:66) of Heavy Chain Variable Regions (H-CVR) from humanized anti-human-PD-1 recombinant antibody, Abs-h-923. Complementarity determining regions of H-CDR1 through H-CDR3 are also shown in Table 3. Fig.3D [fig.3D] shows DNA sequence (SEQ ID NO:67) and amino acid sequence (SEQ ID NO:68) of Light Chain Variable Regions (L-CVR) from humanized anti-human-PD-1 recombinant antibody, Abs-h-923. Complementarity determining regions of L-CDR1 through L-CDR3 are also shown in Table 4. Fig.4A [fig.4A] shows DNA sequence (SEQ ID NO:53) and amino acid sequence (SEQ ID NO:54) of Heavy Chain Variable Regions (H-CVR) from rabbit anti-human-PD-1 recombinant antibody, Abs-r-924. Complementarity determining regions of H-CDR1 through H-CDR3 are also shown in Table 5. Fig.4B [fig.4B] shows DNA sequence (SEQ ID NO:55) and amino acid sequence (SEQ ID NO:56) of Light Chain Variable Regions (L-CVR) from rabbit anti-human-PD-1 recombinant antibody, Abs-r-924. Complementarity determining regions of L-CDR1 through L-CDR3 are also shown in Fig.4C [fig.4C] shows DNA sequence (SEQ ID NO:69) and amino acid sequence (SEQ ID NO:70) of Heavy Chain Variable Regions (H-CVR) from humanized anti-human-PD-1 recombinant antibody, Abs-h-924. Complementarity determining regions of H-CDR1 through H-CDR3 are also shown in Table 7. It is further demonstrated in Example 3A of present invention. Fig.4D [fig.4D] shows DNA sequence (SEQ ID NO:71) and amino acid sequence (SEQ ID NO:72) of Light Chain Variable Regions (L-CVR) from humanized anti-human-PD-1 recombinant antibody, Abs-h-924. Complementarity determining regions of L-CDR1 through L-CDR3 are also shown in Table 8. It is further demonstrated in Example 3B of present invention. Fig.5A [fig.5A] shows DNA sequence (SEQ ID NO:57) and amino acid sequence (SEQ ID NO:58) of Heavy Chain Variable Regions (H-CVR) from rabbit anti-human-PD-1 recombinant antibody, Abs-r-925. Complementarity determining regions of H-CDR1 through H-CDR3 are also shown in Table 9. Fig.5B [fig.5B] shows DNA sequence (SEQ ID NO:59) and amino acid sequence (SEQ ID NO:60) of Light Chain Variable Regions (L-CVR) from rabbit anti-human-PD-1 recombinant antibody, Abs-r-925. Complementarity determining regions of L-CDR1 through L-CDR3 are also shown in Table 10. Fig.5C [fig.5C] shows DNA sequence (SEQ ID NO:73) and amino acid sequence (SEQ ID NO:74) of Heavy Chain Variable Regions (H-CVR) from humanized anti-human-PD-1 recombinant antibody, Abs-h-925. Complementarity determining regions of H-CDR1 through H-CDR3 are also shown in Table 11. It is further demonstrated in Example 3A of present invention. Fig.5D [fig.5D] shows DNA sequence (SEQ ID NO:75) and amino acid sequence (SEQ ID NO:76) of Light Chain Variable Regions (L-CVR) from humanized anti-human-PD-1 recombinant antibody, Abs-h-925. Complementarity determining regions of L-CDR1 through L-CDR3 are also shown in Table 12. It is further demonstrated in Example 3B of present invention. Fig.6A [fig.6A] shows DNA sequence (SEQ ID NO:61) and amino acid sequence (SEQ ID NO:62) of heavy chain variable regions (H-CVR) from rabbit anti-human-PD-1 recombinant antibody, Abs-r-926. Complementarity determining regions of H-CDR1 through H-CDR3 are also shown in Table 13. Fig.6B [fig.6B] shows DNA sequence (SEQ ID NO:63) and amino acid sequence (SEQ ID NO:64) of Light Chain Variable Regions (L-CVR) from rabbit anti-human-PD-1 recombinant antibody, Abs-r-926. Complementarity determining regions of L-CDR1 through L-CDR3 are also shown in Table 14. Fig.6C [fig.6C] shows DNA sequence (SEQ ID NO:77) and amino acid sequence (SEQ ID NO:78) of Heavy Chain Variable Regions (H-CVR) from humanized anti-human-PD-1 recombinant antibody, Abs-h-926. Complementarity determining regions of H-CDR1 through H-CDR3 are also shown in Table 15. Fig.6D [fig.6D] shows DNA sequence (SEQ ID NO:79) and amino acid sequence (SEQ ID NO:80) of Light Chain Variable Regions (L-CVR) from humanized anti-human-PD-1 recombinant antibody, Abs-h-926. Complementarity determining regions of L-CDR1 through L-CDR3 are also shown in Table 16. Fig.7 [fig.7] shows summarizing data on competitive binding to PD-1 of four humanized anti-human-PD-1 recombinant antibodies, Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926 with Nivolumab in competition ELISA in Vitro. Fig.8 [fig.8] shows is a bar graph summarizing the results of a mixed lymphocyte reaction (MLR) assay performed on human PBMCs treated with anti-PD-1 antibodies Abs-h-923, Abs-h-924, Abs-h-925 and Abs-h-926. These results indicate that three of four humanized anti-PD-1 antibodies significantly induce increased levels of IL-2 compared to antibody isotype controls (Negative control), two PD-1 antibodies (reference controls) and Nivolumab (Positive control).

Claims

1. An anti-PD-1 antibody, or antigen binding fragment thereof, which specifically binds to PD-1 and comprises a VH region amino acid sequence comprising SEQ ID NO 74 and a VL region amino acid sequence comprising SEQ ID NO 76.

2. Use of the anti-PD-1 antibody, or antigen binding fragment, according to claim 1 for the detection of PD-1 in vitro, or as a diagnostic agent in vitro.

3. An antibody molecule according to claim 1 for use in treating a cancer, preferably a breast cancer, lung cancer, stomach cancer, colon cancer, kidney cancer or melanoma, or an infectious disease in a subject.