Antibodies that bind to VISTA at acidic pH

Abstract

The present application relates to antibodies that specifically bind to an inhibitory factor of T cell activation (VISTA) containing an immunoglobulin V domain at acidic pH and their use in cancer treatment. In some embodiments, the antibody specifically binds to human VISTA at acidic pH, but does not bind significantly to human VISTA at neutral or physiological pH.

Description

Technical Field

[0001] The present application relates to antibodies that specifically bind to immunoglobulin V domain-containing inhibitor of T-cell activation (VISTA) at acidic pH and the use of said antibodies in cancer treatment.

[0002] Background and Summary of the Invention

[0003] V-domain Ig-containing inhibitor of T-cell activation, or VISTA, is a co-inhibitory member of the B7 family of immunoreceptors expressed by myelomonocytic cells and other leukocytes. However, the mechanism by which VISTA suppresses immune responses is not fully understood.

[0004] The present inventors have found that unlike other known immune receptors, VISTA engages its counter-receptor and selectively works at acidic pH, and has minimal activity at physiological pH (e.g., 7.3-7.4). VISTA can therefore suppress immune responses in acidic microenvironments such as tumor beds or inflammatory sites without disturbing cells circulating in the blood or cells present in non-inflamed non-acidic tissues. In addition, the present inventors have found that anti-VISTA antibodies can be engineered to selectively bind to VISTA at acidic pH, and to bind minimally or not at physiological pH, thereby reflecting the acidic pH selectivity of VISTA itself. Relative to antibodies that bind VISTA at physiological pH, these acidic pH selective antibodies can provide desirable properties for treating diseases such as cancer.

[0005] The present disclosure relates to antibodies that specifically bind to the extracellular domain (ECD) of VISTA, such as human VISTA ("hVISTA" or "huVISTA"), at acidic pH (e.g., under acidic conditions). The present disclosure also relates to antibodies that specifically bind to the extracellular domain (ECD) of VISTA, such as hVISTA, at acidic pH, and have minimal or no binding at neutral or physiological pH. The inventors show herein that the hVISTA-ECD amino acid sequence contains multiple conserved and non-conserved histidine residues, and that the frequency of histidine residues in the ECD of VISTA is exceptionally high relative to other B7 family members and other immunoglobulin superfamily members. (See Figure 1A and Figure 1B In solution, the amino acid histidine has a pK of approximately 6.5. a, meaning that at or below pH 6.5, the histidine residues in the protein are typically protonated and therefore positively charged, while at a pH above pH 6.5, they gradually become non-protonated and charge neutral. Tumor microenvironments and inflamed tissues are typically acidic, and therefore, the VISTA proteins found in these microenvironments may be at least partially protonated at their histidine residues. As discussed herein, the inventors hypothesize that histidine protonation may affect the conformation, surface structure, and / or charge density of VISTA, which in turn may produce pH-specific or pH-selective epitopes for receptor-ligand interactions and antibody binding. Targeting VISTA with antibodies that bind at acidic pH rather than neutral or physiological pH can prevent target-mediated drug disposal via circulating bone marrow mononuclear cells and bone marrow mononuclear cells present in lymphoid organs, thereby improving antibody PK, receptor occupancy, and activity in the tumor microenvironment. Acidic pH-selective antibodies can also improve the specificity of VISTA antibodies for target cells within the tumor rather than in the circulation in therapeutic modalities, such as antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), complement-dependent cytotoxicity (CDC), and delivery of payloads (antibody-drug conjugates). BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Color versions of several of the figures herein are provided with the U.S. Patent and Trademark Office upon request and payment of the necessary fee, provided that color drawings are provided once this application is published and the provisional application becomes publicly available.

[0007] Figure 1A -C shows that the extracellular domain of VISTA contains an exceptionally high frequency of histidine residues, many of which are conserved, and at least some of which may be involved in receptor-ligand binding. Figure 1A A graph showing proteins containing immunoglobulin domains is shown, with the number of amino acid residues in the extracellular domain of each protein plotted on the x-axis and the frequency of histidine residues within the extracellular domain of each protein plotted on the y-axis. The size of each data point corresponds to the total number of histidine residues in the extracellular domain of each protein. Figure 1B The comparison amino acid sequences of the extracellular domains of human, cynomolgus monkey and mouse VISTA are shown. The signal peptide (Sig) and transmembrane domain (TMD) sequence positions are marked. The histidine residues conserved between all three species are shown in bold and underlined; the histidine residues conserved between human and cynomolgus monkey are shown only in bold. Figure 1C A model showing the three-dimensional structure of the human VISTA immunoglobulin domain. Histidine residues are depicted as ball-and-stick traces.

[0008] Figure 2A -B shows a model in which the histidine residues in the extracellular domain of VISTA confer selectivity to the counter-receptor for acidic pH rather than physiological pH. Figure 2A The equilibrium between the absence and presence of protonation of the pyrrolic ammonium group (NH) in histidine residues is shown. The pKa of histidine in solution is 6.5, indicating that histidine residues are more likely to be protonated, and therefore positively charged, at pH 6.5 and lower than at higher pH. Figure 2B Model showing that VISTA selectively engages P-selectin glycoprotein ligand 1 (PSGL-1) or other counter-receptors and ligands ("VISTA-R") at acidic pH. Therefore, antibody binding to the extracellular domain of VISTA at acidic pH, but not at physiological pH, may be critical for inhibiting or modulating VISTA activity.

[0009] Figure 3 VISTA surface expression levels (mean fluorescence intensity (MFI) of anti-VISTA antibody staining) on tumor-infiltrating macrophages, dendritic cells, neutrophils, CD4+ effector T cells, CD4+ regulatory T cells, CD8+ T cells, natural killer (NK) cells, and B cells are shown. VISTA is expressed on many tumor-infiltrating leukocytes, especially bone marrow cells. The tumor microenvironment is typically acidic, allowing VISTA to engage counter-receptors and ligands.

[0010] Figure 4A -G shows that VISTA selectively binds to leukocytes and PSGL-1 at acidic pH, with minimal or no binding at neutral pH, and this binding can be blocked by anti-VISTA antibodies. Figure 4A The left side shows a representative histogram of the binding of fluorescently conjugated recombinant VISTA polymers to activated human CD4+ T cells. From darker gray to lighter, the filled histogram depicts the binding at pH 7.0, 6.5, 6.4, 6.3, 6.1 and 6.0. Some histograms are marked with their corresponding pH. The non-VISTA control polymer binding at pH 6.0 is shown as an unfilled histogram. On the right, the average MFI of VISTA (circles) and control (triangles) polymers bound to activated human CD4+ T cells from two donors at different pH values is shown. Figure 4BRepresentative histograms of the binding of recombinant VISTA polymers to peripheral blood mononuclear cells (PBMCs) at pH 6.0 and pH 7.4 are shown. From darker gray to lighter, the filled histogram depicts the binding to CD19+ B cells, CD4+ T cells, CD8+ T cells, CD56+ NK cells, and CD14+ monocytes at pH 6.0. The unfilled solid and dotted boundary histograms depict the binding to total PBMC lymphocytes and monocytes, respectively, at pH 7.4. Figure 4C The binding of representative recombinant VISTA polymers to activated human CD4+ T cells is shown in the presence of anti-VISTA blocking antibodies (squares) or non-VISTA specific isotype-matched control antibodies (circles). Antibody concentrations are plotted on a logarithmic scale. Nonlinear regression is also shown. Triangles depict background signals from activated human CD4+ T cells that were not stained with recombinant VISTA polymers. Figure 4D Representative two-dimensional flow cytometry plots of recombinant VISTA multimers bound to heparan sulfate-deficient Chinese hamster ovary (CHO) cells (strain pGSD-677, American Type Culture Collection) transfected to express human PSGL-1 at pH 6.0 are shown. Figure 4C Multimer binding was performed in the presence of the anti-VISTA blocking antibody shown in . Cells not stained with recombinant VISTA multimers are shown as controls. PSGL-1 antibody staining is plotted on the y-axis, and VISTA multimer staining is plotted on the x-axis. Figure 4E Representative histograms showing binding of recombinant mouse VISTA-Fc fusion protein to mouse splenocytes at pH 6.0 and pH 7.4. Filled histograms depict binding to CD8+ T cells, CD11b+ myeloid cells, and CD4+ T cells at pH 6.0, from darker gray to lighter. Unfilled histograms depict binding to total splenocytes at pH 7.4. Figure 4F G and G show the effect of pH 6.0 on human peripheral blood mononuclear cells ( Figure 4F ) and neutrophils ( Figure 4G ) Representative histograms of VISTA multimer staining. Cells were stained at pH 7.4, including controls that did not contain VISTA or remained unstained multimers.

[0011] Figure 5A -D shows that VISTA mediates T cell inhibition and cell:cell adhesion preferentially at acidic pH, and both effects can be reversed with anti-VISTA blocking antibodies. Figure 5ARepresentative cell:cell conjugate formation is shown between 293T cells expressing hVISTA or vector control at pH 6.0 and 7.0 (plotted on the y-axis) and CHO cells endogenously expressing cell surface heparan sulfate on the x-axis. Figure 5B is a graph of the frequency of cell conjugates formed between the same cells in the presence of anti-VISTA blocking antibodies, anti-VISTA non-blocking antibodies, or isotype-matched non-VISTA specific control antibodies at pH 6.0. Figure 5C Representative graphs of luciferase activity produced by Jurkat (human T cell line) cells expressing NFkB luciferase reporter genes at various pH values after co-culturing with 293T cells expressing hVISTA and a single-chain variable fragment of the anti-human T cell receptor agonist antibody OKT3 ("artificial antigen presenting cells"). Anti-VISTA blocking antibodies (squares) or isotype-matched non-VISTA specific control antibodies (circles) were added to the co-cultured cells. Figure 5D middle, Figure 5A The data shown in are plotted as the fold increase in luciferase signal upon anti-VISTA antibody treatment relative to control ("effect size").

[0012] Figure 6A -G shows that VISTA can be found in intracellular endosomes, especially Rab11+ recycling endosomes, and can be recycled to and from the cell surface via endosomal trafficking. Figure 6A Shown are the co-localization of VISTA, Rab5 (early endosome marker), Rab7 (late endosome marker), and Rabl 1 (recycling endosome marker) in 293T cells expressing human VISTA. Figure 6B VISTA and Rab11 co-localization in human monocytes is shown. VISTA co-localizes with Rab11+ recycling endosomes in cells. A non-VISTA binding control antibody ("cAb") with the same isotype as the VISTA antibody does not bind to monocytes in a detectable manner. Figure 6C Binding of three anti-VISTA antibodies to recombinant VISTA at pH 7.4 (black), 6.7 (dark grey), and 6 (light grey) is shown. Figure 6D Shown are the sensitivity of VISTA-expressing acute myeloid leukemia (AML) cell lines to killing by the same anti-VISTA antibodies 1 (inverted triangles), 2 (circles), 3 (squares) or a non-VISTA-specific control antibody (triangles) with a cathepsin B-sensitive linker and a cytotoxic payload. Cell viability (Cell Titer - Glo LU) is plotted on the y-axis and antibody concentration is plotted on the x-axis. Figure 6EBinding of anti-VISTA Antibody 3 to hVISTA was compared with an engineered variant ("VISTA mAb 3c") that did not exhibit impaired binding at acidic pH. Figure 6F Shown is an antibody drug-conjugate assay comparing the potency of anti-VISTA antibodies 3 (squares) and 3c (diamonds). Figure 6G Schematic diagram showing endosomal trafficking, where VISTA is recycled to and from the cell surface via early endosomes and recycling ring endosomes.

[0013] Figure 7A -F shows how the anti-VISTA antibody variant library was designed and screened to obtain acidic pH selective antibodies. Figure 7A The amino acid substitutions made in the VH CDR 3 of the anti-human VISTA antibody clone P1-061029 (abbreviated '029) to generate the '029 library for screening are shown. To potentially improve binding to the histidine-rich region of VISTA at acidic pH, the library was substituted with negatively charged amino acids aspartic acid and glutamic acid and pH-responsive histidine. X = H, D or E. The bracketed sequences were removed from the synthesis to avoid introducing unfavorable factors. A total of 647 unique sequences of P1-061029 HCDR3 with 1-2 mutations were synthesized. Figure 7B Figure 2 shows the iterative screening and selection process of the '029 library for acidic pH selective antibody variants. R indicates the selection round. Figure 7C Representative two-dimensional flow cytometry data are shown, which show the variant pool after 9 rounds of selection. VISTA binding is plotted on the y-axis, and variant antibody expression is plotted on the x-axis. Binding data are shown at various antibody concentrations and pH. Figure 7D Graph showing binding of P1-061029 and its progeny clones to human VISTA at pH 6.0 and 7.4. Figure 7E Graph showing the dissociation rates of P1-061029 and its progeny clones from human VISTA at pH 6.0. Figure 7F Shown are SPR binding data for antibodies P1-068761, P1-068767, and P1-061029 to human VISTA at pH 6.0 and pH 7.4.

[0014] Figure 8A -F shows the acidic pH selective cell binding, blocking and effector activities of VISTA antibodies P1-068761 and P1-068767. Figure 8A and Figure 8B Acidic pH selective antibody PI-068761 ( Figure 8A ) and P1-068767( Figure 8B) The mean fluorescence intensity of cells at approximately pH 6.0 (circles; Figure 8A ), 6.1 (square; third highest curve), 6.2 (triangle; second highest curve), 6.4 (inverted triangle; fourth highest curve, close to the pH 6.1 curve), 6.6 (diamond; fourth curve from the bottom), 7.0 (circle; third curve from the bottom), 7.2 (square; second curve from the bottom), and 8.1 unfilled (triangle; Figure 8A Binding was detected with a fluorescently conjugated anti-human IgG secondary antibody. Figure 8C Binding of P1-068767 (circles) and an isotype-matched nonspecific control antibody (triangles) at 3125 ng / mL to Raji cells ectopically expressing human VISTA at various pH values is shown. 50 ”, i.e. the pH at which 50% of the P1-068767 binding is lost is approximately 6.6. Figure 8D Isotype-matched nonspecific control antibody binding to human monocytes is shown (filled and unfilled circles at pH 7.0 and 6.0, respectively), anti-VISTA mAb 2 ("Control," see Figure 6C , pH 7.0 and 6.0 are filled and unfilled squares, respectively), P1-068761 (filled and unfilled triangles, respectively), and P1-068767 (filled and unfilled inverted triangles, respectively). Binding was detected by a fluorescently conjugated anti-human IgG secondary antibody. Figure 8E Comparable blocking of recombinant VISTA multimer binding to activated human CD4+ T cells at pH 6.0 is shown by P1-061029 (squares), P1-068761 (triangles), and P1-068767 (inverted triangles), while a non-VISTA-specific control antibody (circles) did not block VISTA binding. Figure 8F PI-068761 (triangle) and PI-068767 (inverted triangle) are shown to mediate the effect of antibody-dependent cellular cytotoxicity (ADCC) at physiological pH. PI-061029 (square), non-VISTA specific positive control antibody (circle) and non-VISTA specific negative control antibody (diamond) are also shown. The NK cell specific dissolution of target cells as a percentage of total target cells is plotted on the y-axis, and antibody concentration is plotted on the x-axis. Nonlinear regression is also shown.

[0015] Figure 9 Figure 2 shows enhanced pharmacokinetic (PK) of acidic pH selective anti-VISTA antibodies in cynomolgus monkeys. Figure 6C), VISTA antibody 3 ("acidic pH sensitivity", square, see Figure 6C ) or P1-068767 (triangles) over time.

[0016] Figure 10A and 10B Shown are the binding effects of mutations in the acidic pH selective anti-VISTA antibodies '761 and '767. Figure 10A Shown are kinetic binding data for P1-068761 revertants at pH 7.4, pH 6.7, and pH 6.0 and the positions of their revertants relative to P1-068761. Figure 10B Shown are kinetic binding data for P1-068767 revertants at pH 7.4, pH 6.7, and pH 6.0 and their revertant positions relative to P1-068767.

[0017] Figure 11A -C shows the epitope grouping and localization of various anti-VISTA antibodies. Figure 11A Shown are VISTA epitope competition by P1-068761 and P1-068767 compared to P1-061029 and a VISTA antibody control. Figure 11B and Figure 11C Shown are the results of the comparison with non-blocking hVISTA antibodies (mAb1; Figure 11C ) compared to the blocking hVISTA antibodies listed in Table 14 ( Figure 11B ). Amino acid residues 66 (H) and 162 (A) are designated to indicate the orientation of the molecule. Histidine residues are in grey, and epitope residues are in black.

[0018] Figure 12A -C shows imaged capillary isoelectric focusing (icIEF) data for: Figure 12A :P1-061029, Figure 12B :P1-068761, and Figure 12C : P1-068767. Indicates the isoelectric point (main pi) of the major species and pi markers.

[0019] Figures 13A and B show an alignment of the variable regions of the '029 and '015 progeny clones. Figure 13A shows an alignment of the amino acid sequences of the variable regions of the '029 and its progeny clones. Figure 13B An alignment of the amino acid sequences of the variable regions of '015 and its progeny clones is shown.

[0020] Figure 14A A and B show the nucleotide and amino acid sequences of 41F11 or VISTA.4 VH, indicating the positions of the CDRs.

[0021] Figure 15A A and B show the nucleotide and amino acid sequences of 41F11 or VISTA.4VK1, indicating the positions of the CDRs.

[0022] Figure 16A A and B show the nucleotide and amino acid sequences of 41F11 or VISTA.4VK2, indicating the positions of the CDRs.

[0023] Figure 17A A and B show the nucleotide and amino acid sequences of 41F11 or VISTA.4VK3, indicating the positions of the CDRs.

[0024] Figure 18A Blocking antibody VISTA.4 (pH 6.0, orange downward triangle; pH 7.0, red square), non-blocking antibody VISTA.5 (pH 6.0, green diamond; pH 7.0, blue circle) and non-VISTA binding antibody (pH 6.0, unfilled circle; pH 7.0, unfilled upward triangle) are shown to bind to cells of Raji cells expressing VISTA ectopically. Data represent more than four independent experiments. Figure 18B and 18C Blocking antibody VISTA.4 ( Figure 18B ; pH 6.0, light red; pH 6.7, red; pH 7.4, dark red) and non-blocking antibody VISTA.5 ( Figure 18C ; pH 6.0, light blue; pH 6.7, blue; pH 7.4, dark blue) human VISTA SPR binding sensorgram. Overlay sensorgram is 100nM VISTA binding response, which is normalized to the 'binding' reporter point. These data represent more than four independent experiments. Figure 18D VISTA antibody epitope grouping via VISTA.4 and VISTA.5 cross-blocking is shown. Each column represents a unique clone, and for each clone, light grey shading indicates the lack of cross-blocking and dark grey shading indicates cross-blocking. Also depicted is the binding force at pH 6.0 relative to the binding force at pH 7.4, where dark grey shading indicates that Kd is weakened by more than 3 times at pH 6.0. These data represent a single experiment.

[0025] Figure 19A -C shows VISTA.4 (pH 6.0, dotted line; pH 7.4, solid line) ( Figure 19A ), pH-independent variants of VISTA.4 (pH 6.0, dotted line; pH 7.4, solid line) ( Figure 19B ) and acidic pH selective variants of VISTA.4 (pH 6.0, dotted line; pH 7.4, solid line) ( Figure 19CFigure 3 SPR binding sensorgrams of human VISTA (100-0.2 nM series). These data represent two independent experiments.

[0026] Figure 20A and 20B The epitope of VISTA.4 as determined by MS-HDX is shown (by MS trace Figure 20A and sequence Figure 20B ).

[0027] Figure 21A and 21B Binding of VISTA multimers to activated human CD4+ T cells in the presence of antibodies VISTA.4 (triangles), VISTA.5 (squares), and non-VISTA binding (control, circles) at pH 6.0 is shown. Figure 21B The blocking efficiency of each antibody is shown relative to non-blocking T cells. One-way ANOVA with Dunnett's multiple comparison, ***, P < 0.001. These data represent more than four independent experiments. Error bars depict the standard error of the mean.

[0028] Figure 22A -D shows that antibodies that block VISTA binding at acidic pH are functional. Blocking antibody VISTA.4 (squares), non-blocking antibody VISTA.5 (triangles), and non-VISTA binding (control, circles) antibodies have an effect on the proliferation of human CD4+ T cells co-cultured with 293T cells engineered to express VISTA and a TCR agonist (293T-OKT3-VISTA) Figure 22A ) and interferon-γ production ( Figure 22B ) by displaying CellTrace TM Proliferation was measured as the percentage of cells diluted with Violet. One-way ANOVA with Dunnett's multiple comparisons was used. *, P < 0.05. These data are representative of three independent experiments. Figure 22C Shown with Figure 22A PBMC CD4+ T cells co-cultured with 293T-OKT3-VISTA cells as described in CellTrace TM Representative histograms of Violet dilutions. In the presence of VISTA.4, VISTA.5, non-VISTA binding isotype matching antibodies, or in the absence of 293T-OKT3-VISTA cells (grey filling), cells were co-cultured. As shown in the figure, VISTA.5 and control traces are closely superimposed, while in comparison, VISTA.4 traces are upward and shifted to the left. These data represent two independent experiments. Figure 22DResults from two independent experiments are shown, in which VISTA.4 or an isotype-matched non-VISTA binding control antibody was added to cells cultured with 293T-OKT3 or Figure 22A The frequencies of proliferating T cells after co-culture are plotted in the figure. Paired t-test, ***, P < 0.0001.

[0029] Figure 23A -D shows the effect of VISTA and VISTA.4 blockade on Jurkat T cell activation (as measured by NF-kB inhibition). Figure 23A The effect of pH on NFkB luciferase reporter gene Jurkat T cells co-cultured with 293T-scOKT3-VISTA cells is shown. Error bars depict the standard error of the mean. These data are a composite of three independent experiments. Figure 23B NF-kB luciferase signal in Jurkat NFkB-luciferase cells (circles) co-cultured with 293T-OKT3-VISTA cells as described in Figure 23 is shown. Jurkat cells not co-cultured (upward triangles) were included as controls. Data represent two independent experiments. Error bars depict the standard error of the mean. Figure 23C The effect of pH on VISTA inhibition of human CD4+ T cells is shown. Cells were stimulated with plate-coated OKT3 and VISTA-Fc in the presence of VISTA.4 (upward triangle), VISTA.5 (downward triangle) or non-VISTA binding antibodies (antibody control, square) at a specified pH. Cells stimulated with plate-coated OKT3 and control IgG (VISTA control, black circle) or without OKT3 (no OKT3, grey diamond) stimulation are also shown. These data represent two independent experiments. Figure 23D The effect of pH on VISTA inhibition of human CD8+ T cells is shown. Cells were stimulated with plate-coated OKT3 and VISTA-Fc in the presence of VISTA.4 (upward triangle), VISTA.5 (downward triangle) or non-VISTA binding antibodies (antibody control, square) at a specified pH. Cells stimulated with plate-coated OKT3 and control IgG (VISTA control, circle) or without OKT3 (no OKT3, grey diamond) stimulation are also shown. These data represent two independent experiments.

[0030] Figure 24A-R wild-type C57BL6 mice were implanted with MC38 tumors and treated with a non-binding isotype-matched control antibody (squares), the mouse VISTA blocking antibody VISTA.10 (upward-pointing triangles), a mouse PD-1 blocking antibody (squares), or a combination of VISTA and PD-1 blocking antibodies (purple downward-pointing triangles). (See Figure 24A -D.) All antibodies were mouse IgG1-D265A (Fc inert) isotype. These data represent three independent experiments. Figure 24A -D shows tumor volume over time. n=10 per group. "TF" indicates mice that rejected their tumors. Figure 24E -F shows the intratumoral CD8+ T cells 7 days after the start of treatment ( Figure 24E ) and CD4+ T cells ( Figure 24F ) The frequency of each group was n = 5. One-way ANOVA with Dunnett's multiple comparisons was used, P = 0.0001. Figure 24G and 24H Shown are the median tumor volumes over time in each group of mice (isotype control: circles; anti-PD1 D265A: squares; anti-VISTA D265A: upward-pointing triangles; combination of anti-PD-1 D265A and anti-VISTA D265A: downward-pointing triangles). Figure 24I : VISTA knockout mice and wild-type littermates were implanted with MC38 tumors and treated with either a non-binding isotype-matched control antibody (upper two curves (0 / 7TF and 0 / 5TF, marked with a circle and downward-pointing triangle), or a mouse PD-1 blocking antibody (lower two curves 0 / 5TF and 5 / 8TF, marked with a square and downward-pointing triangle). Median tumor growth and the number of tumor-free (TF) mice at the end of the study relative to the total number of mice are shown next to each curve. These data are representative of two independent experiments. Error bars depict the interquartile range. Figure 24J -M shows MC38 tumors implanted and treated with a non-binding isotype-matched control antibody ( Figure 24J ), mouse PD-1 blocking antibody ( Figure 24K ), a combination of mouse PD-1 blocking antibody and non-pH selective human VISTA blocking antibody P1-061029 ( Figure 24L ) or a combination of mouse PD-1 blocking antibody and acidic pH selective human VISTA blocking antibody P1-068767 ( Figure 24M Figure 2. Tumor volume of human VISTA knock-in (KI) mice treated with VISTA (Figure 2). All antibodies were mouse IgG1-D265A isotype. Tumor volume over time is shown. n = 5-8 per group. These data represent one independent experiment. Figure 24NShown are the serum antibody concentrations of human VISTA knock-in (KI) and wild-type (WT) littermates after intravenous injection of 5 mg / kg of P1-061029 ("VISTA.16") (WT, downward triangles; KI, squares) or P1-068767 ("VISTA.18") (WT, upward triangles; KI, diamonds). The calculated serum mean residence time (MRT) of P1-061029 and P1-068767 in KI mice was estimated to be 4.1 and 71 hours, respectively. N = 4 KI mice and 1-2 WT mice per antibody. These data represent a single experiment. Figure 24O Cynomolgus monkey serum antibody concentrations are shown after intravenous injection of 5 mg / kg of VISTA.4 (circles) or P1-068767 ("VISTA.18") (squares). The calculated serum mean residence time (MRT) of VISTA.4 and P1-068767 was estimated to be 7.6 hours and 717 hours, respectively. N = 1 macaque per antibody. These data represent a single experiment. Unless otherwise specified, error bars depict the standard error of the mean. Figure 24P A and Q show the lack of VISTA antibody single-agent activity in human VISTA knock-in mice. Figure 24J Human VISTA knock-in mice were implanted with MC38 tumors and treated as described in -M. Figure 24R Antibody blood concentrations in wild-type mice treated with a single intravenous injection of 200 μg of anti-mouse VISTA antibody (downward-facing triangles) or an isotype-matched control antibody (squares) are shown. n = 2 per antibody. These data represent two independent experiments. Error bars depict the standard error of the mean.

[0031] Figure 25A -C shows that PD-1 ( Figure 25A )、LAG-3( Figure 25B ) and TIM-3( Figure 25C ). Error bars depict standard error of the mean. In each subsection, the control, anti-PD-1, and anti-VISTA main peaks are closely superimposed on the right side of each figure, while the combined main peak is presented on the left.

[0032] Figure 26A -C shows that VISTA binds to PSGL-1 at acidic pH, and this interaction is blocked by VISTA antibodies P1-061029, P1-068761, P1-068767, and VISTA.4. Figure 26A Shown are BLI binding sensorgrams of P-selectin-Fc and VISTA-Fc binding to captured PSGL1 at pH 6.0 and pH 7.4. Figure 26BA histogram showing that antibodies P1-061029, P1-068761, P1-068767, and VISTA.4 inhibit the binding of PSGL-1 to hVISTA. Figure 26C Antibody blocking of VISTA-Fc binding to CHO-PSGL-1 cells by VISTA.4 (upward triangle) and by anti-PSGL-1 antibody KPL-1 (circle) is shown. These data represent two independent experiments. Error bars depict the standard error of the mean.

[0033] Figure 27A -E shows P1-068767Fab and hVISTA or (in Figure 27E (center) Schematic representation of the co-crystal structure of the non-blocking antibody VISTA.5 and hVISTA. The VISTA IgV domain is characterized by an unusual, histidine-rich extension of its central beta sheet. The VISTA IgV domain was co-crystallized with the P1-068767 antigen-binding fragment (Fab). The crystal structure of the VISTA+P1-068767 complex was determined at high resolution. Figure 27A VISTA IgV domain:P1-068767Fab co-crystal structure is shown. Figure 27A Shown is the overall structure of the VISTA IgV domain in complex with P1-068767 Fab (heavy chain, dark grey; light chain, light grey). Figure 27B Superposition of the VISTA and PD-L1 IgV domains is shown. VISTA histidine residues are depicted in stick diagrams. Figure 27B The IgV domain of VISTA is shown to have an unusual, histidine-rich β-sheet extension. Figure 27C The molecular surface of the PI-068767 epitope as shown by the VISTA+PI-068767 crystal structure is shown (light grey electrostatic surface). Figure 27C Blocking antibodies are shown binding to the histidine-rich β-sheet extension of VISTA. Figure 27D Shown is a magnified view of the interface between VISTA (sketched grey ribbon with epitope residues H121, H122, and H123 depicted as stick figures) and P1-068767 (depicted as an electrostatic surface with its residues E100 and D102 in stick figure format). Figure 27D Acidic pH selectivity of P1-068767 is shown to conjugate VISTA histidine with an acidic residue. Figure 27E The non-blocking antibody VISTA.5 is shown to bind in a different region of hVISTA than P1-068767.

[0034] Figure 28A-K shows that VISTA:PSGL-1 binding specificity is determined by histidine and sulfotyrosine residues. Figure 28A As shown in , human PSGL-1 19-mer Fc recombinant proteins with or without sialyl Lewis X decoration (SLX+ and SLX-, respectively) were produced in cells. BLI binding values of VISTA-Fc and P-selectin-Fc at pH 6.0 (white) and 7.4 (black) are shown as indicated. Data represent a single independent experiment. Figure 28B As shown in , the generated human PSGL-1 19-mer Fc glycopeptide with sialyl Lewis X decoration is separated into a portion with more than 90% tyrosine sulfation (rich in sY) and a portion with less than 1% tyrosine sulfation (lacking sY). The BLI binding values of VISTA-Fc and P-selectin-Fc at pH 6.0 (white) and 7.4 (black) as indicated are shown. These data represent a single independent experiment. As Figures 28C-28D As provided in , human VISTA-Fc recombinant proteins were generated in which the histidine residues at positions 153-155 remained unchanged (WT VISTA) or were replaced with alanine (H2A mutant), aspartic acid (H2D mutant), or arginine (H2R mutant). Figure 28C Shown are BLI binding measurements of wild-type and mutant VISTA-Fc proteins bound to captured PSGL-1 at pH 6.0 and pH 7.4. These data represent a single experiment. Figure 28D Binding of WT VISTA (circles), H2A mutants (squares), H2D mutants (downward facing triangles), and H2R mutants (grey upward facing triangles), as well as controls (diamonds), to CHO-PSGL-1 cells at pH 6.0 is shown. These data represent two independent experiments. Figure 28E Computational model of the complex of the PSGL-1 19-mer glycopeptide (top) and the histidine-rich ligand interface of VISTA (grey ribbon, bottom). VISTA residues H98, H100, H153, and H154 are labeled. PSGL-1 residues Y46, Y48, E56, T57, and Y58 are also labeled. Figure 28FVISTA-Fc inhibition of primary T cell activation at pH 6.8 is shown, as measured by the level of phosphorylated NFkB, where VISTA-Fc is wild-type VISTA (second lane), VISTA H2A mutant (His 153-155 mutated to alanine; third lane), VISTA H2D mutant (His 153-155 mutated to aspartic acid; fourth lane), and VISTA H2R mutant (His 153-155 mutated to arginine; fifth lane). These data represent two independent experiments. Figure 28G and H show captured VISTA.5 (non-blocking antibody), Figure 28G ) and P1-061029 (blocking antibody), Figure 28H ) BLI binding magnitude values for the binding of captured wild-type (WT, extreme left bar), histidine to alanine mutant (H2A, second bar from the left), histidine to aspartic acid mutant (H2D, second bar from the right), and histidine to arginine mutant (H2R, extreme right) VISTA-Fc proteins at specified pH. These data represent an independent experiment. Figure 28I Shown are BLI binding measurements of the anti-PSGL-1 clone KPL1 to the captured population, sulfotyrosine-poor and sulfotyrosine-rich fractions of PSGL-1 19-mer Fc at pH 6.0 (left bar) and pH 7.4 (right bar). These data are representative of one independent experiment. Figure 28J Shown are wild-type PSGL-1 19-mer Fc (WT, left) and tyrosine to alanine mutant PSGL-1 19-mer Fc (Y2A, right) at specified pH with captured VISTA-Fc BLI binding values. These data represent an independent experiment. Figure 28K Figure 3 shows the complex of the PSGL-1 19-mer glycopeptide (top) and the histidine-rich ligand interface of VISTA (grey ribbon, bottom). Figure 28E Another view of the computational model.

[0035] Figure 29 Table showing the binding kinetics of mutant hVISTA proteins to hPSGL-1 or anti-VISTA antibodies. DETAILED DESCRIPTION

[0036] definition

[0037] In this application, the use of "or" means "and / or" unless otherwise stated. In the context of multiple dependent claims, the use of "or" only refers back to one or more preceding independent or dependent claims interchangeably. The terms "comprising," "including," and "having" are used interchangeably herein. According to the present invention, an "isolated" molecule is a molecule that has been removed from its natural environment. Thus, the term "isolated" does not necessarily reflect the degree to which a molecule has been purified.

[0038] The term "polypeptide" refers to a polymer of amino acid residues and is not limited by a minimum length. A "protein" may comprise one or more polypeptides. Such polymers of amino acid residues may contain natural or non-natural amino acid residues and include, but are not limited to, peptides, oligopeptides, dimers, trimers, and multimers of amino acid residues. Full-length proteins and fragments thereof are encompassed by the definition. The term also includes post-expression modifications of the polypeptide, such as glycosylation, sialylation, acetylation, phosphorylation, and similar modifications thereof. In addition, for the purposes of the present invention, "polypeptide" or "protein" refers to a polypeptide or protein comprising modifications such as deletions, additions, and substitutions (generally conservative substitutions in nature) of the native sequence, as long as the protein maintains the desired activity. These modifications may be intentional, such as induced by site-directed mutagenesis, or may be accidental, such as mutations in the host producing the protein or errors caused by PCR amplification. A protein may comprise two or more polypeptides.

[0039] "VISTA" is an abbreviation for T cell activation protein inhibitor containing immunoglobulin V domain, which is a member of the B7 family of immune checkpoint regulatory factors. VISTA is also known as PD-1 homolog (PD1H), B7-H5, C10orf54, differentiation of ESC-1 (Dies-1), platelet receptor Gi24 precursor and death domain 1 α (DD1α). In this article, the term "hVISTA" or "huVISTA" refers to human VISTA protein. The amino acid sequence of hVISTA (including its signal peptide) is provided in SEQ ID NO: 1, and the sequence without signal peptide is provided in SEQ ID NO: 2. (See sequence table below.) The extracellular domain of VISTA or "ECD" or "VISTA-ECD" refers to the part of the VISTA protein located in the extracellular space, which includes SEQ ID NO: 2 amino acids 1-162 in the case of hVISTA. (See also Figure 1B .) The "IgV domain" portion of hVISTA comprises residues 5-135 of SEQ ID NO:2.

[0040] The term "leader peptide" or "leader sequence" refers to a sequence of amino acid residues at the N-terminus of a polypeptide that promotes secretion of the polypeptide from mammalian cells. The leader sequence is cleaved to form the mature protein when the polypeptide is exported from the mammalian cell. Leader sequences can be natural or synthetic, and they can be heterologous or homologous to the protein to which they are linked.

[0041] The term "antibody" or "Ab" is used in the broadest sense herein and encompasses various antibody structures, including but not limited to monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g., bispecific antibodies), and antibody fragments, as long as they exhibit desired antigen-binding activity. As used herein, the term refers to a molecule comprising at least the complementary determining region (CDR) 1, CDR2, and CDR3 of a heavy chain and at least CDR1, CDR2, and CDR3 of a light chain, wherein the molecule is capable of binding to an antigen. The term antibody includes but is not limited to fragments capable of binding to antigens, such as "antigen binding fragments" or "antibody fragments," such as Fv, single-chain Fv (scFv), Fab, Fab', and (Fab')2. The term antibody also includes but is not limited to chimeric antibodies, humanized antibodies, human antibodies, and antibodies of various species such as mice and cynomolgus monkeys.

[0042] The term "heavy chain" or "HC" refers to a polypeptide comprising at least a heavy chain variable region, with or without a leader sequence. In some embodiments, a heavy chain comprises at least a portion of a heavy chain constant region. The term "full-length heavy chain" refers to a polypeptide comprising a heavy chain variable region and a heavy chain constant region, with or without a leader sequence and with or without a C-terminal lysine (K).

[0043] The term "heavy chain variable region" or "VH" refers to the region comprising the heavy chain complementarity determining region (CDR) 1, framework region (FR) 2, CDR2, FR3, and CDR3 of the heavy chain. In some embodiments, the heavy chain variable region further comprises at least a portion of FR1 and / or at least a portion of FR4. As specified below, in some embodiments, the heavy chain CDR1 comprises residues 26-35 of the VH SEQ ID NO herein; the heavy chain CDR2 comprises residues 50-66 of the VH SEQ ID NO herein, and the heavy chain CDR3 comprises residues 99-110 of the VH SEQ ID NO herein. In other embodiments, if specified, the heavy chain CDR1 corresponds to Kabat residues 31 to 35; the heavy chain CDR2 corresponds to Kabat residues 50 to 65; and the heavy chain CDR3 corresponds to Kabat residues 95 to 102. See, for example, Kabat sequences of proteins of immunological importance (1987 and 1991, NIH, Bethesda, Md.). In some embodiments, the heavy chain CDRs are as specified herein, such as in the sequence listing below or in Table 2.

[0044] The term "light chain" or "LC" refers to a polypeptide comprising at least one light chain variable region, with or without a leader sequence. In some embodiments, a light chain comprises at least a portion of a light chain constant region. The term "full-length light chain" refers to a polypeptide comprising a light chain variable region and a light chain constant region, with or without a leader sequence.

[0045] The term "light chain variable region" or "VL" refers to the region comprising the light chain CDR1, FR2, HVR2, FR3, and HVR3. In some embodiments, the light chain variable region further comprises FR1 and / or FR4. As specified below, in some embodiments, the light chain CDR1 comprises residues 24-35 of the VL SEQ ID NO herein; the light chain CDR2 comprises residues 51-57 of the VL SEQ ID NO herein, and the light chain CDR3 comprises residues 90-98 of the VL SEQ ID NO herein. In other embodiments, if specified, the light chain CDR1 corresponds to Kabat residues 24 to 34; the light chain CDR2 corresponds to Kabat residues 50 to 56; and the light chain CDR3 corresponds to Kabat residues 89 to 97. See, for example, Kabat sequences of proteins of immunological importance (1987 and 1991, NIH, Bethesda, Md.). In some embodiments, the light chain CDRs are as specified herein, such as in the sequence listing.

[0046] "Chimeric antibody" refers to an antibody in which a portion of the heavy chain and / or light chain is derived from a specific source or species, while the rest of the heavy chain and / or light chain is derived from a different source or species. In some embodiments, a chimeric antibody refers to an antibody comprising at least one variable region from a first species (such as a mouse, rat, cynomolgus monkey, etc.) and at least one constant region from a second species (such as a human, cynomolgus monkey, etc.). In some embodiments, a chimeric antibody comprises at least one mouse variable region and at least one human constant region. In some embodiments, a chimeric antibody comprises at least one cynomolgus monkey variable region and at least one human constant region. In some embodiments, all variable regions of a chimeric antibody are from a first species and all constant regions of a chimeric antibody are from a second species.

[0047] A "humanized antibody" refers to an antibody in which at least one amino acid in the framework region of a non-human variable region has been replaced by the corresponding amino acid from a human variable region. In some embodiments, a humanized antibody comprises at least one human constant region or a fragment thereof. In some embodiments, a humanized antibody is a Fab, scFv, (Fab')2, etc.

[0048] As used herein, "human antibody" refers to antibodies produced in humans, antibodies produced in non-human animals (such as ), and antibodies selected using in vitro methods (such as phage display) in which the antibody repertoire is based on human immunoglobulin sequences.

[0049] As used herein, a "VISTA antibody" or "anti-VISTA antibody" refers to an antibody that specifically binds to VISTA under at least some conditions, such as acidic pH. In some embodiments, the antibody may be a "huVISTA antibody" or "anti-huVISTA antibody," indicating that it specifically binds to the human VISTA protein under at least some conditions, such as acidic pH. A VISTA antibody that specifically binds to the extracellular domain (ECD) of VISTA may be referred to as, for example, a "VISTA-ECD antibody."

[0050] In some embodiments, the antibody can bind to VISTA with higher affinity at acidic pH than at neutral and / or physiological pH. In some embodiments, the antibody binds to VISTA with higher affinity at acidic pH and only negligibly or non-specifically binds at neutral and / or physiological pH.

[0051] The "K" of the binding of an antibody to a protein (e.g., VISTA-ECD protein) D " or "dissociation constant" is a measure of the affinity or specific binding of an antibody to a protein (e.g., VISTA-ECD protein). Compared to a higher K D , lower K D Indicating improved binding or affinity. K D The “off-rate” or k of antibodies and peptides off or k d and the “association rate” or k on or k a The off-rate and on-rate are the rates at which two binding partners in a system associate and dissociate. Thus, with the on-rate held roughly constant, a slower off-rate yields a higher overall affinity and therefore a lower K. D As used herein, a particular value of "or less" of k off Indicator k off Or the "off-rate" is as specified or slower than the specified rate.

[0052] The term "specific binding" or "specifically binds" or similar terms refers to the binding of two polypeptides, such as an antibody and its polypeptide target. D is smaller than that between two random polypeptides under the same conditions. In other words, K D Smaller than that caused by nonspecific aggregation of peptides in the system.

[0053] In some embodiments, the antibody specifically binds to the VISTA-ECD protein at a specific pH or pH range.Herein, "acidic pH" generally refers to a pH less than 7.0, "alkaline pH" generally refers to a pH higher than 7.0, and "neutral pH" generally refers to a pH of about 7.0.Herein, "physiological pH" refers to the pH under normal (i.e., non-cancerous) physiological conditions, for example, 7.35 to 7.45, or 7.3 to 7.4, such as about 7.4.Herein, phrases such as "combined under acidic conditions" or "combined under physiological conditions" and similar phrases used in the case of two molecules such as VISTA and VISTA binding partners or VISTA and T cells refer to combining under acidic pH and combining under physiological pH, respectively.

[0054] When referring to an antibody that "blocks binding of a ligand (or receptor) or competing antibody to a receptor (or ligand) alone or on a cell" or "inhibits binding of a ligand (or receptor) or competing antibody to a receptor (or ligand) alone or on a cell," binding is blocked if there is a statistically significant overall reduction, e.g., an overall reduction of 50% or greater, e.g., an overall reduction of 75%, 80%, 85%, 90%, 95% or greater, compared to a control. An "anti-VISTA blocking antibody" is an antibody that can block binding of VISTA to PSGL-1 or another VISTA ligand or receptor or heparan sulfate proteoglycan, e.g., under at least some conditions, such as at acidic pH.

[0055] As used herein, "tumor model" refers to an in vivo preclinical assay that can be used to study the biological activity of a VISTA-ECD antibody, and includes xenograft or natural mouse tumor assay systems. In some cases, a tumor model can allow tracking of tumor size or growth after treatment with the antibody, and / or tracking the presence of immune cells such as specific types of T cells or NK cells in the tumor to determine whether the antibody triggers or enhances an immune response.

[0056] As used herein, the term "immunostimulator" refers to a molecule that stimulates the immune system by acting as an agonist of an immunostimulatory molecule (including a costimulatory molecule) or as an antagonist of an immunosuppressive molecule (including a co-inhibitory molecule). Immunostimulatory molecules or immunosuppressive molecules can be immune checkpoint regulatory factors, such as VISTA or another B7 family member or another molecule as further described below. An immunostimulatory agent can be a biologic, such as an antibody or antibody fragment, other proteins or vaccines, or can be a small molecule drug. "Immunostimulatory molecules" include receptors or ligands that act to enhance, stimulate, induce or otherwise "turn on" an immune response. Immunostimulatory molecules as defined herein include costimulatory molecules. "Immunosuppressive molecules" include receptors or ligands that act to reduce, suppress, curb or otherwise "turn off" an immune response. Immunosuppressive molecules as defined herein include co-inhibitory molecules. Such immunostimulatory molecules and immunosuppressive molecules can be, for example, receptors or ligands found on immune cells (such as T cells) or found on cells (such as NK cells) that participate in innate immunity.

[0057] "Percentage (%) of amino acid sequence identity and "homology" relative to a peptide, polypeptide or antibody sequence is defined as the percentage of amino acid residues in a candidate sequence that are identical to the amino acid residues in a particular peptide or polypeptide sequence, after aligning the sequences and, if necessary, introducing gaps to achieve the maximum percentage of sequence identity, and not considering any conservative substitutions as part of the sequence identity. Alignment for the purpose of determining percentage amino acid sequence identity can be achieved in various ways within the skill of the art, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN or MEGALIGN™ (DNASTAR) software. Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithm required for achieving maximum alignment over the full length of the compared sequences.

[0058] The term "trigger" or "enhance" refers to the initiation or increase of any event (such as protein ligand binding), or the initiation or increase of any biological activity (such as an immune response) or phenotypic characteristic, or the initiation or increase of the incidence, degree or likelihood of the activity or characteristic. "Trigger" or "enhancement" is to cause an activity, function and / or amount to begin or increase compared to a reference. Triggering or enhancing does not need to be complete. For example, in certain embodiments, "enhancement" means the ability to cause an overall increase of 20% or greater. In another embodiment, "enhancement" means the ability to cause an overall increase of 50% or greater. In another embodiment, "enhancement" means the ability to cause an overall increase of 75%, 85%, 90%, 95% or greater.

[0059] The term "inhibition" or "inhibit" more generally refers to reducing or stopping any event (such as protein ligand binding), or reducing or stopping any phenotypic characteristic, or reducing or stopping the incidence, extent or likelihood of said characteristic. "Reduce" or "inhibit" is to cause an activity, function and / or amount to decrease, decrease or stagnate compared to a reference. The inhibition or reduction need not be complete. For example, in certain embodiments, "reduce" or "inhibit" means the ability to cause an overall reduction of 20% or greater. In another embodiment, "reduce" or "inhibit" means the ability to cause an overall reduction of 50% or greater. In another embodiment, "reduce" or "inhibit" means the ability to cause an overall reduction of 75%, 85%, 90%, 95% or greater.

[0060] As used herein, "treatment" encompasses any administration or administration of a therapeutic agent for a disease in a human, and includes inhibiting the disease or the progression of the disease or one or more symptoms of the disease, inhibiting or slowing the disease or its progression or one or more of its symptoms, arresting its development, partially or completely relieving the disease or one or more of its symptoms, or preventing the recurrence of one or more symptoms of the disease.

[0061] The terms "subject" and "patient" are used interchangeably herein to refer to a human.

[0062] The term "effective amount" or "therapeutically effective amount" refers to an amount of a drug effective to treat a disease or condition in a subject so as to partially or completely alleviate one or more symptoms. In some embodiments, an effective amount refers to an amount that is effective when administered and for the necessary period of time to achieve the desired therapeutic or preventive result.

[0063] As used herein, the term "cancer" refers to a group of cells that exhibit an abnormally high level of proliferation and growth. Cancer can be benign (also known as a benign tumor), premalignant, or malignant. Cancer cells can be solid cancer cells or leukemia cancer cells. As used herein, the term "tumor growth" refers to the proliferation or growth of one or more cells comprising a cancer, which results in a corresponding increase in the size or extent of the cancer.

[0064] Examples of cancers suitable for the methods of treatment herein include, but are not limited to, carcinomas, lymphomas, blastomas, sarcomas, and leukemias. More specific, non-limiting examples of such cancers include squamous cell carcinoma, small cell lung cancer, pituitary cancer, esophageal cancer, astrocytoma, soft tissue sarcoma, non-small cell lung cancer (including squamous cell non-small cell lung cancer), lung adenocarcinoma, lung squamous carcinoma, peritoneal cancer, hepatocellular carcinoma, gastrointestinal cancer, pancreatic cancer, glioblastoma, cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatoma, breast cancer, colon cancer, colorectal cancer, endometrial or uterine cancer, salivary gland cancer, kidney cancer, renal cell carcinoma, liver cancer, prostate cancer, vulvar cancer, thyroid cancer, liver cancer, brain cancer, endometrial cancer, testicular cancer, bile duct cancer, gallbladder cancer, stomach cancer, melanoma, and various types of head and neck cancer (including head and neck squamous cell carcinoma).

[0065] Administration "in combination with" one or more additional therapeutic agents includes simultaneous (concurrent) and consecutive (sequential) administration in any order.

[0066] A "pharmaceutically acceptable carrier" refers to a non-toxic solid, semi-solid, or liquid filler, diluent, encapsulating material, formulation aid, or vehicle conventional in the art, which is used with the therapeutic agent to form a "pharmaceutical composition" to be administered to a subject. A pharmaceutically acceptable carrier is non-toxic to the recipient at the dosage and concentration employed and is compatible with the other ingredients of the formulation. A pharmaceutically acceptable carrier is appropriate for the formulation being employed. For example, if the therapeutic agent is to be administered orally, the carrier may be a gel capsule. If the therapeutic agent is to be administered subcutaneously, the carrier is ideally non-irritating to the skin and does not cause injection site reactions.

[0067] A "chemotherapeutic agent" is a compound useful in the treatment of cancer. Examples of chemotherapeutic agents that can be administered in the methods herein include, but are not limited to, alkylating agents such as thiotepa and Cyclophosphamide; alkyl sulfonates such as busulfan, improsulfan, and piposulfan; aziridines such as benzodopa, carboquone, meturedopa, and uredopa; ethyleneimines and methylmelamines, including hexamethylmelamine, triethylenemelamine, triethylenephosphoramide, triethylenethiophosphoramide, and trimethylmelamine; polyacetyl groups (especially bullatacin and butadiene); bullatacinone; camptothecin (including its synthetic analogue topotecan); bryostatin; spongestatin; CC-1065 (including its synthetic analogues adozelesin, carzelesin, and bizelesin); nostoc (especially nostoc 1 and nostoc 8); pyrenoidin; duocarmycin (including its synthetic analogues KW-2189 and CB1-TM1); eleuthenoside (including its synthetic analogues KW-2189 and CB1-TM1); therobin; pancratistatin; sarcodictyin; spongistatin; nitrogen mustards such as chlorambucil, naphthiazolin, clofosamide, estramustine, ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, novembichin, phenesterine, prednimustine, trofosfos trofosfamide, uracil mustard; nitrosoureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, and ranimnustine; antibiotics such as enediyne antibiotics (e.g., calicheamicins, especially calicheamicin gamma and calicheamicin omega (see, e.g., Agnew, Chem Intl. Ed. Engl., 33:183-186 (1994); dynemicins, including dynemicin A; bisphosphonates such as clodronate; esperamicin; and neocarzinostatin chromophores and related chromoprotein enediyne antibiotic chromophores), aclacinomycin, actinomycin, authramycin, azoserine, bleomycins, cactinomycin, carabicin, carminomycin, carzinophilin, chromomycins, dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, Doxorubicin (including N-morpholino-doxorubicin, cyano-N-morpholino-doxorubicin, 2-pyrroline-doxorubicin and deoxydoxorubicin), epirubicin, esorubicin, idarubicin, marcellomycin, mitomycin (such as mitomycin C), mycophenolic acid, acid, nogalamycin, olivomycin, peplomycin, potfiromycin, puromycin, quelamycin, rodorubicin, streptonigrin, streptozocin, tubercidin, ubenimex, zinostatin, zorubicin; antimetabolites such as methotrexate and 5-fluorouracil (5-FU); folic acid analogs such as denosumab, pterin), methotrexate, pteropterin, trimetrexate; purine analogs such as fludarabine, 6-mercaptopurine, thiamiprine, thioguanine; pyrimidine analogs such as ancitabine, azacitidine, 6-azauridine, carmofur, cytarabine, dideoxyuridine, deoxyfluridine, enocitabine, floxuridine; androgens such as calusterone, dromostanolone propionate, propionate, epitiostanol, mepitiostane, testolactone; antiadrenergic drugs such as aminoglutethimide, mitotane, and trilostane; folic acid supplements such as folinic acid; aceglatone; aldophosphamide glycoside; aminolevulinic acid; eniluracil; amsacrine; bestrabucil; bisantrene; edatraxate;defofamine; demecolcine; diaziquone; elfornithine; elliptinium acetate; epothilone; etoglucid; gallium nitrate; hydroxyurea; lentinan; lonidainine; maytansinoids, such as maytansine and ansamitocin; mitoguazone; mitoxantrone; mopidanmol; nitraerine; pentostatin; phenamet; pirarubicin; losoxantrone; podophyllinic acid acid); 2-ethylhydrazide; procarbazine; Polysaccharide complex (JHS Natural Products, Eugene, OR); razoxane; rhizoxin; sizofiran; spirogermanium; tenuazonic acid acid; triaziquone; 2,2',2"-trichlorotriethylamine; trichothecenes (particularly T-2 toxin, verracurin A, roridin A, and anguidine); urethane; vindesine; dacarbazine; mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine; cytarabine ("Ara-C"); cyclophosphamide; thiotepa; taxoids, such as Paclitaxel (Bristol-Myers Squibb Oncology, Princeton, NJ), Paclitaxel-free polyoxyethylene ether, albumin-engineered nanoparticle formulation (American Pharmaceutical Partners, Schaumberg, Illinois) and Doxetaxel ( PoulencRorer,Antony,France);Chlorambucil; gemcitabine; 6-thioguanine; mercaptopurine; methotrexate; platinum analogs such as cisplatin, oxaliplatin, and carboplatin; vinblastine; platinum; etoposide (VP-16); ifosfamide; mitoxantrone; vincristine; Vinorelbine; novantrone; teniposide; edatrexate; daunomycin; aminopterin; xeloda; ibandronate; irinotecan (Camptosar, CPT-11) (including regimens using irinotecan with 5-FU and leucovorin); the topoisomerase inhibitor RFS2000; difluoromethylornithine (DMFO); retinoids, such as retinoic acid acid); capecitabine; combretastatin; leucovorin (LV); oxaliplatin, including the oxaliplatin-based regimen (FOLFOX); PKC-α inhibitors, Raf inhibitors, H-Ras inhibitors, EGFR inhibitors (e.g., erlotinib) ) and VEGF-A inhibitors (which reduce cell proliferation), and pharmaceutically acceptable salts, acids or derivatives of any of the above.

[0068] Other non-limiting exemplary chemotherapeutic agents that can be administered in the methods herein include anti-hormonal agents used to modulate or inhibit hormonal effects on cancer, such as antiestrogens and selective estrogen receptor modulators (SERMs), including, for example, tamoxifen (including Tamoxifen), raloxifene, droloxifene, 4-hydroxytamoxifen, trioxifene, keoxifene, LY117018, onapristone, and Toremifene; aromatase inhibitors that inhibit aromatase, which regulates estrogen production in the adrenal glands, such as 4(5)-imidazole, aminoglutethimide, Megestrol acetate, Exemestane, formestane, fadrozole, Vorozole, Letrozole and anastrozole; and antiandrogens, such as flutamide, nilutamide, bicalutamide, leuprolide, and goserelin; and troxacitabine (a 1,3-dioxolane nucleoside cytosine analog); antisense oligonucleotides, particularly those that inhibit the expression of genes in signaling pathways involved in abnormal cell proliferation, such as PKC-α, Ralf, and H-Ras; ribozymes, such as VEGF expression inhibitors (e.g., ribozymes) and HER2 expression inhibitors; vaccines, such as gene therapy vaccines, e.g. vaccine, Vaccines and vaccine; rIL-2; topoisomerase 1 inhibitors; rmRH; and pharmaceutically acceptable salts, acids or derivatives of any of the above.

[0069] "Anti-angiogenic agent" or "angiogenesis inhibitor" refers to a small molecular weight substance, polynucleotide (including, for example, inhibitory RNA (RNAi or siRNA)), polypeptide, isolated protein, recombinant protein, antibody, or conjugate or fusion protein thereof that directly or indirectly inhibits angiogenesis, vasculogenesis, or undesirable vascular permeability. It should be understood that anti-angiogenic agents include those that bind to and block the angiogenic activity of angiogenic factors or their receptors. For example, anti-angiogenic agents that can be administered in the methods herein may include antibodies or other antagonists to angiogenic agents, such as antibodies to VEGF-A (e.g., bevacizumab). ) or antibodies to VEGF-A receptors (e.g., KDR receptor or Flt-1 receptor), anti-PDGFR inhibitors (such as (Imatinib Mesylate), small molecules that block VEGF receptor signaling (e.g., PTK787 / ZK2284, SU6668, (sunitinib malate), AMG706 or small molecules such as those described in International Patent Application WO 2004 / 113304.) Anti-angiogenic agents also include native angiogenesis inhibitors such as angiostatin, endostatin and the like. See, e.g., Klagsbrun and D'Amore (1991) Annu. Rev. Physiol. 53:217-39; Streit and Detmar (2003) Oncogene 22:3172-3179 (e.g., Table 3 listing antiangiogenic therapies for malignant melanoma); Ferrara and Alitalo (1999) Nature Medicine 5(12):1359-1364; Tonini et al. (2003) Oncogene 22:6549-6556 (e.g., Table 2 listing known antiangiogenic factors); and Sato (2003) Int. J. Clin. Oncol. 8:200-206 (e.g., Table 1 listing antiangiogenic agents used in clinical trials).

[0070] As used herein, "growth inhibitory agent" refers to a compound or composition that inhibits the growth of cells (such as cells expressing VEGF) in vitro or in vivo. Thus, the growth inhibitory agent that can be administered in the methods herein can be a growth inhibitor that significantly reduces the percentage of cells (such as cells expressing VEGF) in the S phase. Examples of growth inhibitory agents include, but are not limited to, agents that block cell cycle progression (places other than the S phase), such as agents that induce G1 arrest and M phase arrest. Classical M phase blockers include vinca (vincristine and vinblastine), taxanes, and type II topoisomerase inhibitors, such as doxorubicin, epirubicin, daunorubicin, etoposide, and bleomycin. Agents that block G1 also extend into S phase arrest, such as DNA alkylating agents, such as tamoxifen, prednisone, dacarbazine, nitrogen mustard, cisplatin, methotrexate, 5-fluorouracil, and ara-C. Further information can be found in Mendelsohn and Israel, eds., The Molecular Basis of Cancer, Chapter 1, entitled “Cell cycle regulation, oncogenes, and antineoplastic drugs Murakami et al. (WB Saunders, Philadelphia, 1995), e.g., page 13. Taxanes (paclitaxel and docetaxel) are both anticancer drugs derived from the yew tree. Docetaxel (Taxol) is derived from the European yew tree. Rhone-Poulenc Rorer) is paclitaxel ( Paclitaxel and docetaxel promote the assembly of microtubules from tubulin dimers and stabilize microtubules by preventing depolymerization, which contributes to the arrest of mitosis in cells.

[0071] The term "anti-neoplastic composition" refers to a composition comprising at least one active therapeutic agent suitable for treating cancer. Examples of therapeutic agents include, but are not limited to, chemotherapeutic agents, growth inhibitory agents, cytotoxic agents, agents used in radiotherapy, anti-angiogenic agents, cancer immunotherapeutic agents, apoptotic agents, anti-tubulin agents, and other agents for treating cancer, such as anti-HER-2 antibodies, anti-CD20 antibodies, epidermal growth factor receptor (EGFR) antagonists (e.g., tyrosine kinase inhibitors), HER1 / EGFR inhibitors (e.g., erlotinib), and other agents for treating cancer. Platelet-derived growth factor inhibitors (e.g., (imatinib mesylate), COX-2 inhibitors (e.g., celecoxib), interferons, CTLA4 inhibitors (e.g., the anti-CTLA antibody ipilimumab), ), PD-1 or PD-L1 inhibitors (e.g., ), TIM3 inhibitors (e.g., anti-TIM3 antibodies), cytokines, antagonists (e.g., neutralizing antibodies) that bind to one or more of the following targets: ErbB2, ErbB3, ErbB4, PDGFR-β, BlyS, APRIL, BCMA, CTLA4, TIM3 or VEGF receptor, TRAIL / Apo2, and other biologically active and organic chemical agents, etc. Combinations thereof are also included in the present disclosure.

[0072] Antibodies that specifically bind to VISTA-ECD at acidic pH

[0073] Since VISTA has multiple histidine residues in its extracellular domain (ECD), its fold and overall structure, and a surface available for ligand binding such as antibodies, the pK value of histidine is particularly close at acidic pH compared to neutral pH. a Because the tumor microenvironment is generally acidic, for antibodies to bind to VISTA in those microenvironments, they may need to bind specifically to VISTA at an acidic pH, where at least some surface histidine residues are more likely to be protonated.

[0074] The following sequence listing provides the amino acid sequence of human VISTA (hVISTA) with or without a signal peptide (SEQ ID NO: 1 and SEQ ID NO: 2 (mature hVISTA)). The signal peptide constitutes amino acid residues 1-32 of SEQ ID NO: 1. The extracellular domain (ECD) consists of amino acid residues 1-162 of SEQ ID NO: 2). The IgV domain constitutes amino acid residues 37-167 of SEQ ID NO: 1 and amino acid residues 5-135 of SEQ ID NO: 2. The stem region is at amino acid residues 172-194 of SEQ ID NO: 1 and amino acid residues 136-162 of SEQ ID NO: 2; the transmembrane domain is at amino acid residues 195-216 of SEQ ID NO: 1 and amino acid residues 163-184 of SEQ ID NO: 2. Amino acid residues 187 of SEQ ID NO: 1 and 155 of SEQ ID NO: 2 (bold and underlined) can be D or E, which indicates a polymorphism in hVISTA. The residues are shown in bold and underlined. Thus, SEQ ID NO: 1 and SEQ ID NO: 2 encompass two human polymorphisms at the residues. The histidine residues in the ECD of VISTA are shaded grey.

[0075] Anti-VISTA antibodies (Ab) can specifically bind to VISTA-ECD or a fragment thereof at acidic pH, the fragment comprising, for example, the IgV domain of VISTA, or a region from hVISTA comprising, for example, amino acids 20-95, 20-70, 35-70, 35-95, 35-127, or 37-125 of SEQ ID NO: 2. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 7.0. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 6.8. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 6.5. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 6.3. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 6.0. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 5.8. In certain embodiments, the Ab specifically binds to the VISTA-ECD protein at a pH less than pH 5.5. In certain embodiments, the Ab specifically binds to the VISTA-ECD protein at a pH less than pH 5.3. In certain embodiments, the Ab specifically binds to the VISTA-ECD protein at a pH less than pH 5.0.

[0076] Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 5.0-pH 7.0. Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 5.0-pH 6.5. Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 5.0-pH 6.0. Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 5.5-pH 7.0. Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 5.5-pH 6.5. Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 6.0-6.5.

[0077] Also provided herein is a method for producing a 10 -6 M or smaller K DAn Ab that specifically binds to a VISTA-ECD protein, such as hVISTA-ECD or a fragment thereof comprising the IgV domain of VISTA, or a region from hVISTA comprising, for example, amino acids 20-95, 20-70 35-70, 35-95, 35-127, or 37-125 of SEQ ID NO: 2. In some embodiments, the Ab is expressed in an amount of 10 -7 M or smaller K D In some embodiments, Ab is bound to -8 M or smaller K D In some embodiments, Ab is bound to -9 M's K D In some embodiments, Ab is bound to -10 M or smaller K D For example, Ab can bind at a pH of 6.5 or less. -8 M or smaller K D Binds to VISTA-ECD protein.

[0078] Also provided herein is a method for preparing a 10 -6 M or smaller K D In some embodiments, the Ab is bound to the VISTA-ECD protein. -7 M or smaller K D In some embodiments, Ab is bound to -8 M or smaller K D In some embodiments, Ab is bound to -9 M's K D In some embodiments, Ab is bound to -10 M or smaller K D For example, Ab can be bound at a pH of 6.5 or less, such as a pH in the range of 6.0-6.5. -7 M or smaller K D Bind to VISTA-ECD protein. In addition, the Ab can be 10 -8 M or smaller K D Binds to the VISTA-ECD protein. The Ab can be 10 -9 M or smaller K D Binds to hVISTA-ECD.

[0079] Also provided herein is, for example, at a pH of 6.5 or less, at 25°C or 37°C for 10 -5 s -1 or smaller k off An Ab that specifically binds to a VISTA-ECD protein, such as hVISTA-ECD or a fragment thereof comprising the IgV domain of VISTA, or a region from hVISTA comprising, for example, amino acids 20-95, 20-70 35-70, 35-95, 35-127, or 37-125 of SEQ ID NO: 2. In some embodiments, the Ab has a 10 -4 s -1 or smaller k off In some embodiments, Ab has a 2 10 -4 s -1 or smaller k off In some embodiments, Ab has a 5 10 -4 s -1 or smaller k off In some embodiments, Ab has a 7 10 -4 s -1 or smaller k off In some embodiments, Ab has a pH of 10 at 25°C or 37°C. -3 s -1 or smaller k off In some embodiments, Ab has a 2 10 -3 s -1 or smaller k off In some embodiments, Ab has a 5 10 -3 s -1 or smaller k off In some embodiments, Ab has a 7 10 -3 s -1 or smaller k off In some embodiments, Ab has a pH of 10 at 25°C or 37°C. -2 s -1 or smaller k off In some embodiments, Ab has a pH of 10 at 25°C or 37°C. -1 s -1 or smaller k off For example, Ab can be expressed at a pH of 6.5 or less at 25°C or 37°C for 10 -3 s -1 or smaller koff The Ab can bind specifically to the VISTA-ECD protein at a pH of 6.5 or less and at 25°C or 37°C for 10 -3 s -1 or smaller k off Specifically binds to hVISTA-ECD. In addition, Ab can be used at a pH of 6.5 or less for 10 min at 25°C or 37°C. -2 s -1 or smaller k off Binds specifically to the VISTA-ECD protein.

[0080] Provided herein are Abs that bind to a VISTA-ECD protein, such as hVISTA-ECD, or a fragment thereof comprising the IgV domain of VISTA, or a region from hVISTA comprising, e.g., amino acids 20-95, 20-70, 35-70, or 35-95, 35-95, 35-127, or 37-125 of SEQ ID NO: 2, e.g., at a pH of 6.5 or less, wherein (i) K D is 10 -6 M or smaller, 10 -7 M or smaller, 10 -8 M or smaller, 10 -9 M or smaller or 10 -10 M or less, and (ii) as measured, for example, at 25°C or 37°C, k off Rate is 10 -5 s -1 or smaller, 10 -4 (or 2, 5 or 7 10 -4 )s -1 or smaller, 10 -3 (or 2, 5 or 7 10 -4 )s -1 or smaller, 10 -2 s -1 or less or 10 -1 s -1 For example, Ab can be expressed at a pH of 6.5 or less with a concentration of 10 -7 M or smaller K D and 10 as measured, for example, at 25°C or 37°C -3 s -1 or smaller k off The Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less at a rate of 10 -8 M or smaller K D and 10 as measured, for example, at 25°C or 37°C -3 s -1or smaller k off The Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less at a rate of 10 -8 M or smaller K D and 10 as measured, for example, at 25°C or 37°C -2 s -1 or smaller k off For example, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less at a rate of 10 -7 M or smaller K D and 10 as measured, for example, at 25°C or 37°C -3 s -1 or smaller k off The Ab can bind to hVISTA-ECD at a pH of 6.5 or less at a rate of 10 -9 M or smaller K D and 10 as measured, for example, at 25°C or 37°C -3 s -1 or smaller k off The Ab can bind to hVISTA-ECD at a pH of 6.5 or less at a rate of 10 -9 M or smaller K D and 10 as measured, for example, at 25°C or 37°C -2 s -1 or smaller k off The Ab can bind to hVISTA-ECD at a pH of 6.5 or less at a rate of 10 -8 M or smaller K D and 10 as measured, for example, at 25°C or 37°C -4 (or 2, 5 or 7 10 -4 )s -1 or smaller k off The Ab can bind to hVISTA-ECD at a pH of 6.5 or less at a rate of 10 -8 M or smaller K D and 10 as measured, for example, at 25°C or 37°C -5 (or 2, 5 or 7 10 -5 )s -1 or smaller k off The Ab can bind to hVISTA-ECD at a pH of 6.5 or less at a rate of 10 -9 M or smaller K D and 10 as measured, for example, at 25°C or 37°C -4 (or 2, 5 or 7 10 -4 )s -1 or smaller k offThe Ab can bind to hVISTA-ECD at a pH of 6.5 or less at a rate of 10 -9 M or smaller K D and 10 as measured, for example, at 25°C or 37°C -5 (or 2, 5 or 7 10 -5 )s -1 or smaller k off Rate of binding to hVISTA-ECD.

[0081] Provided herein are, for example, at a pH of 6.5 or less, at 25°C or 37°C for 10 4 M -1 s -1 or higher k on In some embodiments, the Ab can be 10 5 M -1 s -1 or higher k on In some such embodiments, Ab can be 10 6 M -1 s -1 or higher k on In some such embodiments, Ab can be 10 7 M -1 s -1 or higher k on For example, Ab may bind at a pH of 6.5 or less with a 10 6 M -1 s -1 or higher k on Binds to the VISTA-ECD protein. For example, the Ab may bind to the VISTA-ECD protein at a pH of 6.5 or less with a 10 6 M -1 s -1 or higher k on Binds to the ECD of hVISTA.

[0082] Provided herein are Abs that bind to a VISTA-ECD protein, e.g., at a pH of 6.5 or less, wherein (i) K D is 10 -6 M or smaller, 10 -7 M or smaller, 10 -8 M or smaller, 10 -9 M or smaller or 10 -10 M or less, and (ii) as measured, for example, at 25°C or 37°C, k on is 10 4M -1 s -1 or higher, 10 5 M -1 s -1 or higher, 10 6 M -1 s -1 or higher, 10 7 M -1 s -1 For example, Ab can be expressed at a pH of 6.5 or less with a pH of 10 -7 M or smaller K D and 10 as measured, for example, at 25°C or 37°C 6 M -1 s -1 or higher k on For example, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less at a rate of 10 -8 M or smaller K D and 10 as measured, for example, at 25°C or 37°C 6 M -1 s -1 or higher k on For example, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less at a rate of 10 -7 M or smaller K D and 10 as measured, for example, at 25°C or 37°C 6 M -1 s -1 or higher k on For example, the Ab can bind to hVISTA-ECD at a pH of 6.5 or less at a rate of 10 -8 M or smaller K D and 10 as measured, for example, at 25°C or 37°C 6 M -1 s -1 or higher k on Rate of binding to hVISTA-ECD.

[0083] In some embodiments, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less, where K D is 10 - 7 M or less, and as measured, for example, at 25°C or 37°C, k off is 10 -5 s -1 or less, 2 10 -5 s -1 or less, 5 10- 5 s -1 or less, 7 10 -5 s -1 or smaller, 10 -4 s -1 or less, 2 10 -4 s -1 or less, 5 10 -4 s -1 or less, 7 10 -4 s -1 or smaller, 10 -3 s -1 or less, 2 10 -3 s -1 or less, 5 10 -3 s -1 or less, 7 10 -3 s -1 or smaller, 10 -2 s -1 or less or 10 -1 s -1 In some embodiments, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less, where K D is 10 -9 M or less, and as measured, for example, at 25°C or 37°C, k off is 10 -5 s -1 or smaller, 10 -4 s -1 or smaller, 10 -3 s -1 or smaller, 10 -2 s -1 or less or 10 -1 s -1 In some such embodiments, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less, wherein the K D is 10 -10 M or less, and as measured, for example, at 25°C or 37°C, k off is 10 -5 s -1 or smaller, 10 -4 s -1 or smaller, 10 -3 s -1 or smaller, 10 -2 s -1 or less or 10 -1 s -1 or smaller.

[0084] In some embodiments, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less, where K D is 10 - 7 M or less, and as measured, for example, at 25°C or 37°C, k on is 10 4 M -1 s -1 or higher, 10 5 M -1 s -1 or higher, 10 6 M -1 s -1 or higher, 10 7 M -1 s -1 In some embodiments, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less, where K D is 10 -8 M or less, and as measured, for example, at 25°C or 37°C, k on is 10 4 M -1 s -1 or higher, 10 5 M -1 s -1 or higher, 10 6 M -1 s -1 or higher, 10 7 M -1 s -1 In some embodiments, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less, where K D is 10 -9 M or less, and as measured, for example, at 25°C or 37°C, k on is 10 4 M -1 s -1 or higher, 10 5 M -1 s -1 or higher, 10 6 M -1 s -1 or higher, 10 7 M -1 s -1 In some embodiments, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less, where K D is 10 -10M or less, and as measured, for example, at 25°C or 37°C, k on is 10 4 M -1 s -1 or higher, 10 5 M -1 s -1 or higher, 10 6 M -1 s -1 or higher, 10 7 M -1 s -1 or higher.

[0085] In some embodiments, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less, where K D is 10 - 7 M or less, and as measured, for example, at 25°C or 37°C, k off is 10 -5 s -1 or smaller, 10 -4 s -1 or smaller, 10 -3 s -1 or smaller, 10 -2 s -1 or less or 10 -1 s -1 or less, and as measured, for example, at 25°C or 37°C, k on is 10 4 M -1 s -1 or higher, 10 5 M -1 s -1 or higher, 10 6 M -1 s -1 or higher, 10 7 M -1 s -1 In some embodiments, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less, where K D is 10 -8 M or less, and as measured, for example, at 25°C or 37°C, k off is 10 -5 s -1 or smaller, 10 -4 s -1 or smaller, 10 -3 s -1 or smaller, 10 -2 s -1or less or 10 -1 s -1 or less, and as measured, for example, at 25°C or 37°C, k on is 10 4 M -1 s -1 or higher, 10 5 M -1 s -1 or higher, 10 6 M -1 s -1 or higher, 10 7 M -1 s -1 In some embodiments, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less, where K D is 10 -9 M or less, and as measured, for example, at 25°C or 37°C, k off is 10 -5 s -1 or smaller, 10 -4 s -1 or smaller, 10 -3 s -1 or smaller, 10 -2 s -1 or less or 10 -1 s -1 or less, and as measured, for example, at 25°C or 37°C, k on is 10 4 M -1 s -1 or higher, 10 5 M -1 s -1 or higher, 10 6 M -1 s -1 or higher, 10 7 M -1 s -1 In some embodiments, the Ab can bind to the VISTA-ECD protein at a pH of 6.5 or less, where K D is 10 -10 M or less, and as measured, for example, at 25°C or 37°C, k off is 10 -5 s -1 or smaller, 10 -4 s -1 or smaller, 10 -3 s -1 or smaller, 10 -2 s -1 or less or 10-1 s -1 or less, and as measured, for example, at 25°C or 37°C, k on is 10 4 M -1 s -1 or higher, 10 5 M -1 s -1 or higher, 10 6 M -1 s -1 or higher, 10 7 M -1 s -1 or higher.

[0086] As also shown above, in some of the above embodiments, the VISTA-ECD protein is hVISTA-ECD, or is a part of hVISTA-ECD, such as an IgV domain. In some of the above embodiments, Ab can specifically bind to an epitope comprising SEQ ID NO: amino acids 20-95 of 2. In some of the above embodiments, Ab can specifically bind to an epitope comprising SEQ ID NO: amino acids 20-70 of 2. In some of the above embodiments, Ab can specifically bind to an epitope comprising SEQ ID NO: amino acids 35-95 of 2. In some of the above embodiments, Ab can specifically bind to an epitope comprising SEQ ID NO: amino acids 35-70 of 2. In some of the above embodiments, the epitope is a three-dimensional epitope that not only comprises one of the above portions of SEQ ID NO: 2 from residues 20-95, 20-70, 35-95 or 35-70, and also comprises another portion of SEQ ID NO: 2, such as residues 95-105 of SEQ ID NO: 2. In certain embodiments, Ab binds to the epitope of hVISTA bound by Ab described in WO2015 / 097536. For example, Ab can compete or cross-compete with hVISTA for binding with Ab disclosed in WO2015 / 097536. In certain embodiments, Ab binds to the conformational epitope of human VISTA. In certain embodiments, Ab binds to the conformational epitope of human VISTA comprising or present in the following: SEQ ID NO:2 residues 103-111 and SEQ ID NO:2 residues 136-146. In certain embodiments, Ab binds to the conformational epitope of human VISTA comprising or present in the following: SEQ ID NO:2 residues 24-36, 54-65 and 100-102. In certain embodiments, Ab binds to a conformational epitope comprising or present in the following: SEQ ID NO:2 residues 24-36, 54-65 and 100-102. In certain embodiments, Ab binds to an amino acid residue in the FG loop of human VISTA. In some embodiments, the Ab binds to a polypeptide comprising amino acid residues 35 to 127 and / or 37-125 of SEQ ID NO:2.In some embodiments, the Ab binds to a VISTAECD polypeptide comprising amino acid residues 350-127 of SEQ ID NO: 2, or a portion thereof, but the antibody does not bind or binds with reduced affinity to a VISTAECD polypeptide comprising amino acid substitutions, or a portion thereof, wherein substitution (1) is a substitution of one of the following amino acid residues: T35, Y37, K38, T39, Y41, R54, T61, F62, Q63, L65, H66, L67, H68, H69, F97, L115, V117, I119, H121, H122, S124, E125, R127, and SEQ ID NO: 2, or (2) is a substitution of one of the following amino acid residues: Y37, T39, R54, F62, Q63, H66, L115, V117, I119, S124, or E125. In some embodiments, the anti-VISTA antibodies have the same binding characteristics (or substantially the same binding characteristics) as the antibodies described herein, e.g., as listed in the Examples and / or claims.

[0087] Some of the above antibodies may exhibit different binding affinities to the VISTA-ECD protein depending on the pH. Certain Abs that specifically bind to the VISTA-ECD protein under acidic conditions, such as at pH 6.5 or less, also specifically bind to the VISTA-ECD protein with similar affinity at neutral and / or alkaline pH (i.e., they are "pan-binders"). For example, some such Abs may bind to the VISTA-ECD protein at both pH 6.5 and pH 7.0 with a binding affinity of 10. -7 M or smaller K D (at a constant temperature, such as 25°C or 37°C) to the VISTA-ECD protein such that the K at pH 6.5 D K at pH 7.0 D Some of these Abs can be expressed at pH 6.5 and at pH 7.0 at a rate of 10 -8 M or smaller K D (at a constant temperature, such as 25°C or 37°C) to the VISTA-ECD protein such that the K at pH 6.5 D K at pH 7.0 D Some of these Abs can be expressed at pH 6.5 and at pH 7.0 at a rate of 10 -8 M or smaller K D (at a constant temperature, such as 25°C or 37°C) to hVISTA-ECD, such that the K at pH 6.5 D K at pH 7.0 D within 1.5 times of .

[0088] Under acidic conditions, for example, certain Abs that specifically bind to the VISTA-ECD protein at pH 6.5 or less may bind to the VISTA-ECD protein with lower affinity under neutral, physiological, and / or alkaline conditions ("pH sensitive binders" or "pH sensitive Abs"). Under acidic conditions, for example, certain Abs that specifically bind to the VISTA-ECD protein at pH 6.5 or less may not significantly bind to the VISTA-ECD protein under neutral, physiological, and / or alkaline conditions, for example, barely detectably bind. For example, in some embodiments, an Ab may bind to the VISTA-ECD protein at pH 6.5 with a low affinity of 10 -8 M or smaller K D and at pH 7.0 and / or pH 7.4 with a concentration greater than 10 -8 M's K D In some such embodiments, the Ab can bind to the VISTA-ECD protein at pH 6.5 at 10 -8 M or smaller K D and at pH 7.0 and / or pH 7.4 with a K greater than that at pH 6.5 D 1.5 times K D In certain embodiments, a pH-sensitive Ab is provided that binds to the VISTA-ECD protein with a K at pH 7.0. D At least 1.5-fold, 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, 300-fold, 500-fold, 1000-fold, or 5000-fold lower than the K at pH 6.5. D (at a constant temperature, e.g., 25° C. or 37° C.) specifically binds to a VISTA-ECD protein. For example, in some cases, the Ab has a K at pH 6.0 that is at least 1.5-fold, 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, 300-fold, 500-fold, 1000-fold, or 5000-fold lower relative to pH 7.0 and / or pH 7.4 or higher. D (at a constant temperature, such as 25°C or 37°C) to the VISTA-ECD protein.

[0089] In certain embodiments, the Ab is expressed under acidic conditions at a k relative to its k under neutral, physiological, or alkaline conditions. off Lower k off Specifically binds to the VISTA-ECD protein. In certain embodiments, an Ab is provided that has a k under acidic conditions as measured, for example, at 25°C or 37°C, compared to that at pH 7.0 and / or pH 7.4. off at least 1.5-fold, 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, or 1000-fold lower than the k at pH 6.5. offBinds to the VISTA-ECD protein. In other words, the dissociation rate at acidic pH is slower than at neutral pH. For example, in some embodiments, the Ab has a k at pH 6.0 that is at least 1.5-fold, 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, or 1000-fold lower relative to pH 7.0 and / or pH 7.4, as measured, for example, at 25°C or 37°C. off In certain embodiments, an Ab is provided that specifically binds to the VISTA-ECD protein at a K of 0.040 at pH 7.4, as measured, for example, at 25°C or 37°C. off at least 1.5-fold, 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, or 1000-fold lower than the k at pH 6.5. off In some embodiments, the Ab has a k at pH 6.0 that is at least 1.5-fold, 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, or 1000-fold lower relative to pH 7.4, as measured, for example, at 25° C. or 37° C. off In certain embodiments, an Ab is provided that specifically binds to the VISTA-ECD protein at a K of 0.001 at pH 7.0-7.4, as measured, for example, at 25°C or 37°C. off at least 1.5-fold, 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, or 1000-fold lower than the k at pH 6.0-6.5. off Binds to VISTA-ECD protein.

[0090] In certain embodiments, the Ab is expressed with a higher k under acidic conditions relative to neutral, physiological, or alkaline conditions. on Specifically binds to the VISTA-ECD protein. In certain embodiments, an Ab is provided that has a k at pH 7.0 and / or pH 7.4 under acidic conditions, as measured, for example, at 25°C or 37°C. on at least 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, or 1000-fold the k at pH 6.5. on Binds to the VISTA-ECD protein. For example, in some embodiments, the Ab has a k at pH 7.0 and / or pH 7.4 as measured, for example, at 25°C or 37°C. on at least 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, or 1000-fold the k at pH 6.0. on Binds specifically to the VISTA-ECD protein.

[0091] In certain embodiments, the Ab specifically binds to the VISTA-ECD protein at a pH at which at least one histidine residue, e.g., His 98 of SEQ ID NO: 1, is protonated. In certain embodiments, the Ab specifically binds to the VISTA-ECD protein at a pH at which a majority of the histidine residues in the ECD are protonated, which is expected to be pH 6.5 or less, e.g., between pH 6.0 and pH 6.5.

[0092] Also contemplated herein are Abs that specifically bind to the VISTA-ECD protein with higher affinity at neutral, physiological, or alkaline pH relative to acidic pH, provided that the binding affinity at acidic pH remains high. For example, an Ab may bind to the VISTA-ECD protein with a higher affinity at pH 6.5 and pH 7.0. -8 M or smaller K D The Ab binds to the VISTA-ECD protein, but the Ab binds to the VISTA-ECD protein with a K that is at least 1.5-fold, 2-fold, 5-fold, 10-fold, 20-fold, 50-fold, 100-fold, 300-fold, 500-fold, 1000-fold lower at pH 7.0 than at pH 6.5. D combination.

[0093] Abs that share one or more of the above characteristics of this section are also encompassed herein. D 、k off 、k on The above properties of specific epitopes should not be viewed separately. Thus, an Ab may bind to an epitope in one of the regions described above comprising SEQ ID NO: 2 and may also have pan-binding or pH-sensitive or pH-selective binding properties as described above, such as its K at different pHs. D 、k off or k on as indicated by one or more of the behaviors.

[0094] In any of the above embodiments, the Ab can be, for example, a full-length antibody (i.e., comprising a full-length heavy chain (with or without a C-terminal lysine) and a full-length light chain), or an antigen-binding fragment, such as a Fab fragment, a Fab' fragment, a (Fab')2 fragment, a scFv fragment, a Fv fragment, or the Ab can be a chimeric, humanized or human antibody, or the Ab can be a bispecific or multispecific antibody.

[0095] Determining the extent to which an Ab binds to a VISTA-ECD protein at a given pH can be performed using several different methods. For example, by surface plasmon resonance (SPR), such as by An exemplary SPR assay comprises using a CM4 sensor chip with an immobilized capture reagent (e.g., using Anti-Human Fc Capture Kit, GE Healthcare Cat. No. BR-1008-39, or Anti-mouse capture kit, GE Healthcare catalog number BR-1008-39) captures one or several antibodies, and a series of concentrations of VISTA antigen as analyte flow to determine the binding kinetics and affinity in a running buffer with a desired pH. In one embodiment, VISTA is injected at a flow rate of 30ul / min at two to five concentrations in the range of 0.1nM to 500nM (e.g., 0.1nM, 1nM, 10nM, 100nM, 500nM), with a maximum association time of four minutes and a maximum dissociation time of ten minutes. Between binding cycles, the capture surface is regenerated following the manufacturer's instructions for the corresponding capture kit. All data are double-referenced using a reference flow cell and a blank injection. The T200 evaluation software fits the data with simple 1:1 kinetics to a Langmuir binding model with mass shift.The SPR method described in the Examples can also be used.

[0096] The affinity of Ab for VISTA ECD polypeptides can be determined using cells expressing VISTA ECD polypeptides, PSGL-1 or heparan sulfate on the surface, the method including flow cytometry, and wherein the binding of Ab to cell-bound VISTA-ECD is determined at a given pH (e.g., pH 6.5 or less). An exemplary flow cytometry assay comprises the following: 293T cells or other cells ectopically expressing hVISTA ECD are resuspended in a buffer composed of HBSS+1% BSA adjusted to the desired pH, for example, adjusted to pH 6.0 with MES or adjusted to pH 7.4 with HEPES. Anti-hVISTA Ab (e.g., human IgG) is serially diluted from approximately 20 μg / mL and incubated with resuspended cells at 4°C for 30 minutes. The cells are then washed twice with the same buffer, maintaining the desired pH (e.g., at a pH of 6.0 or 7.4), and incubated with a second antibody conjugated to a fluorophore that recognizes the first antibody (e.g., human IgG) and is stable at a reduced pH. The cells were then washed as before and immediately acquired on a BD Fortessa or other flow cytometer without fixation. The affinity of the Abs for the VISTA ECD polypeptides can be determined as described in the Examples.

[0097] In certain embodiments, Ab bound to hVISTA ECD blocks hVISTA from binding to its binding partner (e.g., VISTA receptor) on, for example, a cell. Inhibition or blocking may be 100% or at least 99%, 95%, 90%, 85%, 80%, 75% or 50%. In certain embodiments, Ab binds to VISTA-ECD protein at acidic pH, such as pH 6.5 or less, and inhibits the binding of VISTA to its binding partner by at least 50%, such as at least 75%, 80%, 85%, 90%, 95% or 100%. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 7.0 and inhibits the binding of VISTA to its binding partner by at least 50%. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 6.8 and inhibits the binding of VISTA to its binding partner by at least 50%. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 6.5 and inhibits the binding of VISTA to its binding partner by at least 50%. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 6.3 and inhibits the binding of VISTA to its binding partner by at least 50%. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 6.0 and inhibits the binding of VISTA to its binding partner by at least 50%. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 5.8 and inhibits the binding of VISTA to its binding partner by at least 50%. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 5.5 and inhibits the binding of VISTA to its binding partner by at least 50%. In certain embodiments, Ab specifically binds to VISTA-ECD protein at a pH less than pH 5.3 and inhibits the binding of VISTA to its binding partner by at least 50%. In certain embodiments, the Ab specifically binds to the VISTA-ECD protein at a pH less than pH 5.0 and inhibits the binding of VISTA to its binding partner by at least 50%.

[0098] Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 5.0-pH 7.0 and inhibit the binding of VISTA to its binding partner by at least 50%. Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 5.0-pH 6.5 and inhibit the binding of VISTA to its binding partner by at least 50%. Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 5.0-pH 6.0 and inhibit the binding of VISTA to its binding partner by at least 50%. Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 5.5-pH 7.0 and inhibit the binding of VISTA to its binding partner by at least 50%. Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 5.5-pH 6.5 and inhibit the binding of VISTA to its binding partner by at least 50%. Certain Abs specifically bind to the VISTA-ECD protein at a pH in the range of pH 6.0-6.5 and inhibit the binding of VISTA to its binding partner by at least 50%. The inhibition of binding can be determined as described in the Examples.

[0099] The VISTA binding partner can be PSGL-1, such as human PSGL-1. The sequences of human PSGL-1 isoforms are provided herein as SEQ ID NOs: 3-10. VISTA binds to PSGL-1 with or without sialyl Lewis X. The binding partner can also be, for example, heparan sulfate proteoglycans present on certain cells.

[0100] Inhibition of binding to a VISTA binding partner can be determined by measuring the inhibition of binding of VISTA (or VISTA ECD or VISTA IgV domain or VISTA positive cells) to cells to which VISTA binds (e.g., T cells (e.g., activated or inactivated CD4+ T cells, CD8+ T cells), NK cells, or other cells to which VISTA binds) in the presence and absence of the antibody. An exemplary experiment that can be used to determine whether an antibody inhibits the binding of VISTA to its binding partner or T cells expressing the binding partner is a flow cytometry assay, such as an assay comprising the following: human peripheral blood mononuclear cells from a donor, buffy coat, or leukopak are resuspended in a buffer consisting of HBSS + 1% BSA adjusted to the desired pH, for example, to pH 6.0 with MES or to pH 7.4 with HEPES. The cells were then incubated at 4°C for 30 minutes with 20 μg / mL of a recombinant chimeric protein consisting of hVISTA ECD (VISTA-Fc) fused to human IgG1 Fc and varying concentrations of candidate VISTA blocking antibodies or control antibodies. The cells were then washed twice in the same buffer, maintaining the desired pH (e.g., a pH at 6.0 or 7.4), and incubated at 4°C for 30 minutes with a fluorophore-conjugated secondary antibody that recognizes VISTA-Fc, but not the candidate blocking antibody or control antibody, and is stable at a reduced pH. The cells were then washed as described above and acquired immediately on a BD Fortessa or other flow cytometer without fixation. Inhibition of binding can be determined, for example, as described in the Examples.

[0101] In specific embodiments, the Ab described herein can trigger or enhance an immune response, such as an antigen-specific immune response. In certain embodiments, the Ab stimulates T cell activity, particularly at acidic pH, such as that found in a tumor microenvironment. Stimulation of T cell activity can be measured, for example, in a mixed lymphocyte reaction (MLR) or in an in vitro assay using antigen-presenting cells (natural or artificial) and T cells. Stimulation of T cell activity can also be measured using, for example, the Jurkat assay described in the Examples. Stimulation of T cell activity can also be measured as described in other Examples herein, for example, by measuring IFN-γ secretion from T cells, wherein enhanced IFN-γ secretion indicates T cell stimulation. Secretion of other cytokines from activated T cells can also be measured. In certain embodiments, as described in the Examples, signal transduction of activated T cells, such as NF-kB levels, is measured.

[0102] In specific embodiments, the Abs described herein inhibit cell adhesion, which can be measured as described in the Examples.

[0103] The activity of anti-VISTA Abs can also be shown in monocyte assays, ADCC assays, and ADCP assays, particularly at acidic pH, such as that found in the tumor microenvironment.

[0104] In certain embodiments, the anti-VISTA Ab inhibits tumor growth in a tumor model, such as a human VISTA gene knock-in tumor model.

[0105] As shown in the Examples herein, anti-VISTA Ab is recycled in endosomes to enhance the pharmacokinetic (PK) properties of the antibody, i.e., half-life, requiring anti-VISTA antibodies to bind to VISTA under acidic conditions. Therefore, it is also expected that as further described herein at low pH, for example, anti-VISTA Ab bound to VISTA at a pH of 6.5 or lower will have a longer acceptable half-life relative to VISTA antibodies that are not bound to VISTA at acidic pH.

[0106] Exemplary hVISTA-ECD Binding Abs

[0107] Provided herein are Abs that preferentially bind to hVISTA(ECD) at acidic pH (e.g., under acidic conditions) relative to physiological or neutral pH.

[0108] In certain embodiments, the anti-hVISTA Ab comprises a heavy chain variable region ("VH") comprising the VH CDR1, CDR2, and / or CDR3 of any one of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises a VH comprising the VH CDR1, CDR2, and CDR3 of any one of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises a VH comprising the VH CDR1, CDR2, and CDR3 of any one of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises a VH comprising the VH CDR1, CDR2, and / or CDR3 of: P1-061029 or P1-061015, or a progeny thereof,Such as P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1 -069061, P1-069063, P1-069065, P1-069067, P1-069069, P1-069071, P1-0 69073, P1-069075, P1-069077, P1-061015, P1-068736, P1-068738, P1-0687 40. P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-068752 P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-0687 61_E55A_E56N, P1-068761_E30D, P1-068761_E30D_E55A, P1-068761_E56N _H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100f F. P1-068761_E55A_E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_ E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_E32Y_E55 A. P1-068761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G , P1-068761_E32Y_E100fF, P1-068767_D52N_D102V, P1-068767_D52N, P1-0 68767_D52N_E55A, P1-068767_E55A_D102V, P1-068767_D102V, P1-068767 _E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068767_E30D, P 1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100f F. P1-068767_D52N_E100fF, P1-068767_E100fF, P1-068767_E30D_E100fF,Or a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P) or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17. The VH CDR1, CDR2, and CDR3 of each of these species comprise amino acid positions 26-35 (VH CDR1), 50-66 (VH CDR2), and 99-110 (VH CDR3) of the VH sequences of each of the above antibody species provided in the sequence listing below. The CDRs are also underlined and in bold on each of the VH sequences of the above antibody species provided in the sequence listing below.

[0109] In certain embodiments, the anti-hVISTA Ab comprises a VL comprising a VL CDR1, CDR2, and CDR3 of any one of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises a VL comprising a VH of one of the following: CDR1, CDR2 and / or CDR3: P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1-069061, P1-069063, P1-069065, P1-069067, P1-069069, P1-069071, P1-069073, P1-069075, 69077, P1-061015, P1-068736, P1-068738, P1-068740, P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-068752P1-068 754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-068761_E55A_E56N, P1-068761_E30D, P1-068761_E30D_E55A, P1-068 761_E56N_H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100fF, P1-068761_E55A_E100fF, P1-068761_H100G_ E100fF, P1-068761_E30D_E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_E32Y_E55A, P1-068761_E32Y_E56N, P1-06 8761_E30D_E32Y, P1-068761_E32Y_H100G, P1-068761_E32Y_E100fF, P1-068767_D52N_D102V, P1-068767_D52N, P1-068767_D52N_E5 5A, P1-068767_E55A_D102V, P1-068767_D102V, P1-068767_E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068767_E30D,P1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100fF, P1-068767_D52N_E100fF, P1-068767_E100fF, P1-068767_E30D_E100fF, or a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P) or P1065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17. The VLCDR1, CDR2 and CDR3 of each of these species comprise amino acid positions 24-35 (VL CDR1), 51-57 (VL CDR2) and 90-98 (VL CDR3) of the VL sequence of each of the above antibody species provided in the sequence listing below. The CDRs are also underlined and in bold in each of those sequences.

[0110] In certain embodiments, the anti-hVISTA Ab comprises a VH comprising the VH CDR1, CDR2 and / or CDR3 of any of the anti-hVISTA Abs provided herein and a VL comprising the CDR1, CDR2 and / or CDR3 of any of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises a VH comprising the VH CDR1, CDR2 and CDR3 of any of the anti-hVISTA Abs provided herein and a VL comprising the CDR1, CDR2 and CDR3 of any of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises a VH comprising the VH CDR1, CDR2 and / or CDR3 of: P1-061029 or P1-061015 or a progeny thereof,Such as P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1 -069061, P1-069063, P1-069065, P1-069067, P1-069069, P1-069071, P1-0 69073, P1-069075, P1-069077, P1-061015, P1-068736, P1-068738, P1-0687 40. P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-068752 P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-0687 61_E55A_E56N, P1-068761_E30D, P1-068761_E30D_E55A, P1-068761_E56N _H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100f F. P1-068761_E55A_E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_ E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_E32Y_E55 A. P1-068761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G , P1-068761_E32Y_E100fF, P1-068767_D52N_D102V, P1-068767_D52N, P1-0 68767_D52N_E55A, P1-068767_E55A_D102V, P1-068767_D102V, P1-068767 _E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068767_E30D, P 1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100f F. P1-068767_D52N_E100fF, P1-068767_E100fF, P1-068767_E30D_E100fF,or a VISTA.4 (also referred to as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17; and a VL containing the following: VL of CDR1, CDR2 and CDR3: P1-061029 or P1-061015 or progeny thereof,Such as P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1 -069061, P1-069063, P1-069065, P1-069067, P1-069069, P1-069071, P1-0 69073, P1-069075, P1-069077, P1-061015, P1-068736, P1-068738, P1-0687 40. P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-068752 P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-0687 61_E55A_E56N, P1-068761_E30D, P1-068761_E30D_E55A, P1-068761_E56N _H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100f F. P1-068761_E55A_E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_ E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_E32Y_E55 A. P1-068761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G , P1-068761_E32Y_E100fF, P1-068767_D52N_D102V, P1-068767_D52N, P1-0 68767_D52N_E55A, P1-068767_E55A_D102V, P1-068767_D102V, P1-068767 _E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068767_E30D, P 1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100f F. P1-068767_D52N_E100fF, P1-068767_E100fF, P1-068767_E30D_E100fF,Or a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17.

[0111] In some embodiments, an anti-hVISTA Ab may comprise:

[0112] (a) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-061029, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-061029;

[0113] (b) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-061015, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-061015;

[0114] (c) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068757, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068757;

[0115] (d) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068759, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068759;

[0116] (e) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761;

[0117] (f) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068763, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068763;

[0118] (g) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068765, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068765;

[0119] (h) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068767, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767;

[0120] (i) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068769, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068769;

[0121] (j) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068771, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068771;

[0122] (k) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068773, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068773;

[0123] (1) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068775, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068775;

[0124] (m) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-069059, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-069059;

[0125] (n) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-069061, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-069061;

[0126] (o) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-069063, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-069063;

[0127] (p) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-069065, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-069065;

[0128] (q) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-069067, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-069067;

[0129] (r) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-069069, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-069069;

[0130] (s) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-069071, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-069071;

[0131] (t) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-069073, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-069073;

[0132] (u) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-069075, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-069075;

[0133] (v) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-069077, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-069077;

[0134] (w) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068736, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068736;

[0135] (x) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068738, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068738;

[0136] (y) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068740, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068740;

[0137] (z) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068742, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068742;

[0138] (aa) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068744, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068744;

[0139] (bb) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068746, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068746;

[0140] (cc) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068748, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068748;

[0141] (dd) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068750, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068750;

[0142] (ee) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068752, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068752;

[0143] (ff) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068754, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068754;

[0144] (gg) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_E55A, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E55A;

[0145] (hh) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_H100G, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_H100G;

[0146] (ii) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_E56N, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E56N;

[0147] (jj) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068761_E55A_E56N, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E55A_E56N;

[0148] (kk) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_E30D, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E30D;

[0149] (11) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068761_E30D_E55A, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E30D_E55A;

[0150] (mm) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068761_E56N_H100G, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E56N_H100G;

[0151] (nn) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068761_E30D_H100G, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E30D_H100G;

[0152] (oo) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068761_E30D_E56N, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E30D_E56N;

[0153] (pp) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_E100fF, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E100fF;

[0154] (qq) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068761_E55A_E100fF, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E55A_E100fF;

[0155] (rr) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068761_H100G_E100fF, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_H100G_E100fF;

[0156] (ss) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_E30D_E100fF, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E30D_E100fF;

[0157] (tt) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_E56N_E100fF, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E56N_E100fF;

[0158] (uu) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_E32Y, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E32Y;

[0159] (vv) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_E32Y_E55A, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E32Y_E55A;

[0160] (ww) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_E32Y_E56N, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E32Y_E56N;

[0161] (xx) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068761_E30D_E32Y, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E30D_E32Y;

[0162] (yy) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_E32Y_H100G, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E32Y_H100G;

[0163] (zz) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068761_E32Y_E100fF, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068761_E32Y_E100fF;

[0164] (aaa) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068767_D52N_D102V, and a VL comprising the amino acid sequence of VLCDR1, CDR2, and CDR3 of P1-068767_D52N_D102V;

[0165] (bbb) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068767_D52N, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_D52N;

[0166] (ccc) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068767_D52N_E55A, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_D52N_E55A;

[0167] (ddd) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068767_E55A_D102V, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_E55A_D102V;

[0168] (eee) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068767_D102V, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_D102V;

[0169] (fff) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068767_E55A, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068767_E55A;

[0170] (ggg) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068767_E30D_D52N, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_E30D_D52N;

[0171] (hhh) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068767_E30D_D102V, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_E30D_D102V;

[0172] (iii) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068767_E30D, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-068767_E30D;

[0173] (jjj) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-068767_E30D_E55A, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_E30D_E55A;

[0174] (kkk) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068767_E100fF_D102V, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_E100fF_D102V;

[0175] (111) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068767_E55A_E100fF, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_E55A_E100fF;

[0176] (mmm) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068767_D52N_E100fF, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_D52N_E100fF;

[0177] (nnn) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068767_E100fF, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_E100fF;

[0178] (ooo) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of P1-068767_E30D_E100fF, and a VL comprising the VL CDR1, CDR2, and CDR3 of P1-068767_E30D_E100fF;

[0179] (ppp) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of VISTA.4, and a VL comprising VL CDR1, CDR2, and CDR3 of VISTA.4;

[0180] (qqq) a VH comprising the amino acid sequence of VH CDR1, CDR2, and CDR3 of VISTA.4_VL_A64G, and a VL comprising the VL CDR1, CDR2, and CDR3 of VISTA.4_VL_A64G;

[0181] (rrr) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-070976, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-070976;

[0182] (sss) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-071799, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-071799;

[0183] (ttt) a VH comprising the amino acid sequences of VH CDR1, CDR2, and CDR3 of P1-071801, and a VL comprising VL CDR1, CDR2, and CDR3 of P1-071801;

[0184] (uuu) A VH comprising the amino acid sequences of VH CDR1, CDR2 and CDR3 of P1-065333, and a VL comprising VL CDR1, CDR2 and CDR3 of P1-065333.

[0185] In addition, the following sequence listing provides the heavy and light chain variable region sequences and full-length heavy and light chain sequences of the antibodies listed above with an IgG1.3 heavy chain constant region (unless a different HC constant region is indicated in the table), and the positions of their VH CDR1, CDR2, and CDR3, as well as VL CDR1, CDR2, and CDR3, are indicated by amino acid residues, and the CDRs in each VH and VL sequence are bolded and underlined. Thus, for example, the VH CDR1 of P1-061029 comprises amino acids 26-35 of SEQ ID NO: 67, while the VH CDR2 comprises amino acids 50-66 of SEQ ID NO: 67, and the VH CDR3 comprises amino acids 99-110 of SEQ ID NO: 67, etc., as indicated by the bolded and underlined amino acids of SEQ ID NO: 67 shown in the sequence listing.

[0186] In certain embodiments, the anti-hVISTA Ab comprises a VH comprising the amino acid sequence of the VH of any of the anti-h VISTA Abs provided herein. Individual VH sequences of specific antibody species provided herein are listed in the sequence listing. In certain embodiments, the anti-hVISTA Ab comprises a VH comprising the amino acid sequence of the following VH: P1-061029 or P1-061015 or a progeny thereof,Such as P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1 -069061, P1-069063, P1-069065, P1-069067, P1-069069, P1-069071, P1-0 69073, P1-069075, P1-069077, P1-061015, P1-068736, P1-068738, P1-0687 40. P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-068752 P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-0687 61_E55A_E56N, P1-068761_E30D, P1-068761_E30D_E55A, P1-068761_E56N _H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100f F. P1-068761_E55A_E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_ E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_E32Y_E55 A. P1-068761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G , P1-068761_E32Y_E100fF, P1-068767_D52N_D102V, P1-068767_D52N, P1-0 68767_D52N_E55A, P1-068767_E55A_D102V, P1-068767_D102V, P1-068767 _E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068767_E30D, P 1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100f F. P1-068767_D52N_E100fF, P1-068767_E100fF, P1-068767_E30D_E100fF,Or a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17.

[0187] In certain embodiments, the anti-hVISTA Ab comprises a VH CDR1, CDR2, and CDR3 comprising the amino acid sequence of the VH CDRs of any of the anti-hVISTA Abs provided herein, and comprises a VH that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH of any of the anti-hVISTA Abs provided herein. The Ab comprises a VH comprising an amino acid sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of the VH of P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775 , P1-069059, P1-069061, P1-069063, P1-069065, P1-069067, P1-069069, P1-069071, P1-069073, P1-069075, P1-06907 7. P1-061015, P1-068736, P1-068738, P1-068740, P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-06875 2P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-068761_E55A_E56N, P1-068761_E30D, P1-0687 61_E30D_E55A, P1-068761_E56N_H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100fF, P1-06876 1_E55A_E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1- 068761_E32Y_E55A, P1-068761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G, P1-068761_E32Y_E100fF,P1-068767_D52N_D102V、P1-068767_D52N、P1-068767_D52N_E55A、P1-068767_E55A_D102V、P1-068767_D102V、 P1-068767_E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068767_E30D, P1-068767_E30D_E55A, P1 -068767_E100fF_D102V, P1-068767_E55A_E100fF, P1-068767_D52N_E100fF, P1-068767_E100fF, P1-068767_E30D_E100fF, or VISTA.4 (also known as 41F11)-derived antibodies described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P) or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17.

[0188] In certain embodiments, the anti-hVISTA Ab comprises a VH consisting of the amino acid sequence of the VH of any of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises a VH consisting of the amino acid sequence of the VH of: P1-061029 or P1-061015 or a progeny thereof,Such as P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1 -069061, P1-069063, P1-069065, P1-069067, P1-069069, P1-069071, P1-0 69073, P1-069075, P1-069077, P1-061015, P1-068736, P1-068738, P1-0687 40. P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-068752 P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-0687 61_E55A_E56N, P1-068761_E30D, P1-068761_E30D_E55A, P1-068761_E56N _H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100f F. P1-068761_E55A_E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_ E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_E32Y_E55 A. P1-068761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G , P1-068761_E32Y_E100fF, P1-068767_D52N_D102V, P1-068767_D52N, P1-0 68767_D52N_E55A, P1-068767_E55A_D102V, P1-068767_D102V, P1-068767 _E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068767_E30D, P 1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100f F. P1-068767_D52N_E100fF, P1-068767_E100fF, P1-068767_E30D_E100fF,Or a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17.

[0189] In certain embodiments, the anti-hVISTA Ab comprises a VL comprising the amino acid sequence of the VL of any of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises a VL comprising the amino acid sequence of the VL of: P1-061029 or P1-061015 or a progeny thereof,Such as P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1 -069061, P1-069063, P1-069065, P1-069067, P1-069069, P1-069071, P1-0 69073, P1-069075, P1-069077, P1-061015, P1-068736, P1-068738, P1-0687 40. P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-068752 P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-0687 61_E55A_E56N, P1-068761_E30D, P1-068761_E30D_E55A, P1-068761_E56N _H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100f F. P1-068761_E55A_E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_ E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_E32Y_E55 A. P1-068761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G , P1-068761_E32Y_E100fF, P1-068767_D52N_D102V, P1-068767_D52N, P1-0 68767_D52N_E55A, P1-068767_E55A_D102V, P1-068767_D102V, P1-068767 _E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068767_E30D, P 1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100f F. P1-068767_D52N_E100fF, P1-068767_E100fF, P1-068767_E30D_E100fF,Or a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17.

[0190] In certain embodiments, the anti-hVISTA Ab comprises a VL CDR1, CDR2, and CDR3 comprising the amino acid sequence of the VL CDR of any of the anti-hVISTA Abs provided herein, and comprises a VL that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VL of any of the anti-hVISTA Abs provided herein. The Ab comprises a VL comprising an amino acid sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the amino acid sequence of the VL of P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775 , P1-069059, P1-069061, P1-069063, P1-069065, P1-069067, P1-069069, P1-069071, P1-069073, P1-069075, P1-06907 7. P1-061015, P1-068736, P1-068738, P1-068740, P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-06875 2P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-068761_E55A_E56N, P1-068761_E30D, P1-0687 61_E30D_E55A, P1-068761_E56N_H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100fF, P1-06876 1_E55A_E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1- 068761_E32Y_E55A, P1-068761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G, P1-068761_E32Y_E100fF,P1-068767_D52N_D102V、P1-068767_D52N、P1-068767_D52N_E55A、P1-068767_E55A_D102V、P1-068767_D102V、 P1-068767_E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068767_E30D, P1-068767_E30D_E55A, P1 -068767_E100fF_D102V, P1-068767_E55A_E100fF, P1-068767_D52N_E100fF, P1-068767_E100fF, P1-068767_E30D_E100fF, or VISTA.4 (also known as 41F11)-derived antibodies described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P) or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17.

[0191] In certain embodiments, the anti-hVISTA Ab comprises a VL consisting of the amino acid sequence of the VL of any of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises a VL consisting of the amino acid sequence of the VL of: P1-061029 or P1-061015 or a progeny thereof,Such as P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1 -069061, P1-069063, P1-069065, P1-069067, P1-069069, P1-069071, P1-0 69073, P1-069075, P1-069077, P1-061015, P1-068736, P1-068738, P1-0687 40. P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-068752 P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-0687 61_E55A_E56N, P1-068761_E30D, P1-068761_E30D_E55A, P1-068761_E56N _H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100f F. P1-068761_E55A_E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_ E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_E32Y_E55 A. P1-068761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G , P1-068761_E32Y_E100fF, P1-068767_D52N_D102V, P1-068767_D52N, P1-0 68767_D52N_E55A, P1-068767_E55A_D102V, P1-068767_D102V, P1-068767 _E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068767_E30D, P 1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100f F. P1-068767_D52N_E100fF, P1-068767_E100fF, P1-068767_E30D_E100fF,Or a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17.

[0192] In certain embodiments, the anti-hVISTA Ab comprises a VH comprising the amino acid sequence of the VH of any of the anti-hVISTA Abs provided herein, and comprises a VL comprising the amino acid sequence of the VL of any of the anti-hVISTA Abs provided herein. In certain of these embodiments, the anti-hVISTA The Ab comprises a VH comprising the amino acid sequence of the VH of P1-061029 or P1-061015 or a progeny thereof, such as P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1-069061, P1-069063, P1-069065, P1-069067, P1-069069, P1- 069071, P1-069073, P1-069075, P1-069077, P1-061015, P1-068736, P1-068738, P1-068740, P1-068742, P1-068744, P1-068766, P1- 068748, P1-068750, P1-068752P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-068761_E55A_E56N, P1-06876 1_E30D, P1-068761_E30D_E55A, P1-068761_E56N_H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100fF, P1-0 68761_E55A_E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_ E32Y_E55A, P1-068761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G, P1-068761_E32Y_E100fF, P1-068767_D52N_D1 02V, P1-068767_D52N, P1-068767_D52N_E55A, P1-068767_E55A_D102V, P1-068767_D102V, P1-068767_E55A, P1-068767_E30D_D52N,P1-068767_E30D_D102V, P1-068767_E30D, P1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100fF, P1-068767_D52N_E100fF, P1-068767_E100fF or P1-068767_E30D_E100fF; and a VL comprising the amino acid sequence of the VL of P1-061029 or P1-061015. In certain embodiments, the anti-hVISTA Ab comprises a VH and VL comprising the amino acid sequence of VH and VL of P1-061029 or P1-061015 or a progeny thereof, such as P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1-069061, P1-069063, P1 -069065, P1-069067, P1-069069, P1-069071, P1-069073, P1-069075, P1-069077, P1-061015, P1-068736, P1-068738 , P1-068740, P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-068752P1-068754, P1-068761_E55A, P1- 068761_H100G, P1-068761_E56N, P1-068761_E55A_E56N, P1-068761_E30D, P1-068761_E30D_E55A, P1-068761_E56N _H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100fF, P1-068761_E55A_E100fF, P1-068761_H 100G_E100fF, P1-068761_E30D_E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_E32Y_E55A, P1-068 761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G, P1-068761_E32Y_E100fF, P1-068767_D52N_D102V,P1-068767_D52N, P1-068767_D52N_E55A, P1-068767_E55A_D102V, P1-068767_D 102V, P1-068767_E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068 767_E30D, P1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100fF, P1-068767_D52N_E100fF, P1-068767_E100fF, or P1-068767_E30D_E100f. In certain embodiments, the VH and VL comprise the amino acid sequences of the following VH and VL: a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17.

[0193] In certain embodiments, the anti-hVISTA Ab comprises a VH CDR1, CDR2, and CDR3 comprising the amino acid sequence of the VH CDR of any of the anti-hVISTA Abs provided herein, and a VL CDR1, CDR2, and CDR3 comprising the amino acid sequence of the VL CDR of any of the hVISTA Abs provided herein, and further comprises a VH and VL that are each at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the corresponding VH and VL of any of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises all 6 CDRs of the anti-hVISTA Ab provided herein, and further comprises VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the corresponding VH and VL of the anti-hVISTA Ab, such as the VH and VL of: P1-061029 or P1-061015, or a progeny thereof,Such as P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1 -069061, P1-069063, P1-069065, P1-069067, P1-069069, P1-069071, P1-0 69073, P1-069075, P1-069077, P1-061015, P1-068736, P1-068738, P1-0687 40. P1-068742, P1-068744, P1-068766, P1-068748, P1-068750, P1-068752 P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-0687 61_E55A_E56N, P1-068761_E30D, P1-068761_E30D_E55A, P1-068761_E56N _H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100f F. P1-068761_E55A_E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_ E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_E32Y_E55 A. P1-068761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G , P1-068761_E32Y_E100fF, P1-068767_D52N_D102V, P1-068767_D52N, P1-0 68767_D52N_E55A, P1-068767_E55A_D102V, P1-068767_D102V, P1-068767 _E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V, P1-068767_E30D, P 1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100f F. P1-068767_D52N_E100fF, P1-068767_E100fF, P1-068767_E30D_E100fF,Or a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17.

[0194] In certain embodiments, the anti-hVISTA Ab comprises a VH and a VL consisting of the amino acid sequences of the VH and VL of any of the anti-hVISTA Abs provided herein. Ab comprises a VH and a VL each consisting of the amino acid sequence of the following VH and VL: P1-061029 or P1-061015 or a progeny thereof, such as P1-061029, P1-068757, P1-068759, P1-068761, P1-068763, P1-068765, P1-068767, P1-068769, P1-068771, P1-068773, P1-068775, P1-069059, P1-069061, P1-069063, P1-069065, P1-069067, P1-069069, P 1-069071, P1-069073, P1-069075, P1-069077, P1-061015, P1-068736, P1-068738, P1-068740, P1-068742, P1-068744, P1-068766, P1-06 8748, P1-068750, P1-068752P1-068754, P1-068761_E55A, P1-068761_H100G, P1-068761_E56N, P1-068761_E55A_E56N, P1-068761_E30D , P1-068761_E30D_E55A, P1-068761_E56N_H100G, P1-068761_E30D_H100G, P1-068761_E30D_E56N, P1-068761_E100fF, P1-068761_E55A _E100fF, P1-068761_H100G_E100fF, P1-068761_E30D_E100fF, P1-068761_E56N_E100fF, P1-068761_E32Y, P1-068761_E32Y_E55A, P1-0 68761_E32Y_E56N, P1-068761_E30D_E32Y, P1-068761_E32Y_H100G, P1-068761_E32Y_E100fF, P1-068767_D52N_D102V, P1-068767_D52N , P1-068767_D52N_E55A, P1-068767_E55A_D102V, P1-068767_D102V, P1-068767_E55A, P1-068767_E30D_D52N, P1-068767_E30D_D102V,P1-068767_E30D, P1-068767_E30D_E55A, P1-068767_E100fF_D102V, P1-068767_E55A_E100fF, P1-068767_D52N_E100fF, P1-068767_E100fF, or P1-068767_E30D_E100fF. In certain embodiments, the amino acid sequences of VH and VL each consist of the amino acid sequences of the VH and VL of a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17.

[0195] Anti-hVISTA Abs may include:

[0196] (a) a VH comprising the amino acid sequence of VH of P1-061029, and a VL comprising the amino acid sequence of VL of P1-061029;

[0197] (b) a VH comprising the amino acid sequence of VH of P1-061015, and a VL comprising the amino acid sequence of VL of P1-061015;

[0198] (c) a VH comprising the amino acid sequence of VH of P1-068757, and a VL comprising the amino acid sequence of VL of P1-068757;

[0199] (d) a VH comprising the amino acid sequence of VH of P1-068759, and a VL comprising the amino acid sequence of VL of P1-068759;

[0200] (e) a VH comprising the amino acid sequence of VH of P1-068761, and a VL comprising the amino acid sequence of VL of P1-068761;

[0201] (f) a VH comprising the amino acid sequence of VH of P1-068763, and a VL comprising the amino acid sequence of VL of P1-068763;

[0202] (g) a VH comprising the amino acid sequence of VH of P1-068765, and a VL comprising the amino acid sequence of VL of P1-068765;

[0203] (h) a VH comprising the amino acid sequence of VH of P1-068767, and a VL comprising the amino acid sequence of VL of P1-068767;

[0204] (i) a VH comprising the amino acid sequence of VH of P1-068769, and a VL comprising the amino acid sequence of VL of P1-068769;

[0205] (j) a VH comprising the amino acid sequence of VH of P1-068771, and a VL comprising the amino acid sequence of VL of P1-068771;

[0206] (k) a VH comprising the amino acid sequence of VH of P1-068773, and a VL comprising the amino acid sequence of VL of P1-068773;

[0207] (1) a VH comprising the amino acid sequence of VH of P1-068775, and a VL comprising the amino acid sequence of VL of P1-068775;

[0208] (m) a VH comprising the amino acid sequence of VH of P1-069059, and a VL comprising the amino acid sequence of VL of P1-069059;

[0209] (n) a VH comprising the amino acid sequence of VH of P1-069061, and a VL comprising the amino acid sequence of VL of P1-069061;

[0210] (o) a VH comprising the amino acid sequence of VH of P1-069063, and a VL comprising the amino acid sequence of VL of P1-069063;

[0211] (p) a VH comprising the amino acid sequence of VH of P1-069065, and a VL comprising the amino acid sequence of VL of P1-069065;

[0212] (q) a VH comprising the amino acid sequence of VH of P1-069067, and a VL comprising the amino acid sequence of VL of P1-069067;

[0213] (r) a VH comprising the amino acid sequence of VH of P1-069069, and a VL comprising the amino acid sequence of VL of P1-069069;

[0214] (s) a VH comprising the amino acid sequence of VH of P1-069071, and a VL comprising the amino acid sequence of VL of P1-069071;

[0215] (t) a VH comprising the amino acid sequence of VH of P1-069073, and a VL comprising the amino acid sequence of VL of P1-069073;

[0216] (u) a VH comprising the amino acid sequence of VH of P1-069075, and a VL comprising the amino acid sequence of VL of P1-069075;

[0217] (v) a VH comprising the amino acid sequence of VH of P1-069077, and a VL comprising the amino acid sequence of VL of P1-069077;

[0218] (w) a VH comprising the amino acid sequence of VH of P1-068736, and a VL comprising the amino acid sequence of VL of P1-068736;

[0219] (x) a VH comprising the amino acid sequence of VH of P1-068738, and a VL comprising the amino acid sequence of VL of P1-068738;

[0220] (y) a VH comprising the amino acid sequence of VH of P1-068740, and a VL comprising the amino acid sequence of VL of P1-068740;

[0221] (z) a VH comprising the amino acid sequence of VH of P1-068742, and a VL comprising the amino acid sequence of VL of P1-068742;

[0222] (aa) a VH comprising the amino acid sequence of VH of P1-068744, and a VL comprising the amino acid sequence of VL of P1-068744;

[0223] (bb) a VH comprising the amino acid sequence of VH of P1-068746, and a VL comprising the amino acid sequence of VL of P1-068746;

[0224] (cc) a VH comprising the amino acid sequence of VH of P1-068748, and a VL comprising the amino acid sequence of VL of P1-068748;

[0225] (dd) a VH comprising the amino acid sequence of VH of P1-068750, and a VL comprising the amino acid sequence of VL of P1-068750;

[0226] (ee) a VH comprising the amino acid sequence of VH of P1-068752, and a VL comprising the amino acid sequence of VL of P1-068752;

[0227] (ff) a VH comprising the amino acid sequence of VH of P1-068754, and a VL comprising the amino acid sequence of VL of P1-068754;

[0228] (gg) a VH comprising the amino acid sequence of VH of P1-068761_E55A, and a VL comprising the amino acid sequence of VL of P1-068761_E55A;

[0229] (hh) a VH comprising the amino acid sequence of VH of P1-068761_H100G, and a VL comprising the amino acid sequence of VL of P1-068761_H100G;

[0230] (ii) a VH comprising the amino acid sequence of VH of P1-068761_E56N, and a VL comprising the amino acid sequence of VL of P1-068761_E56N;

[0231] (jj) a VH comprising the amino acid sequence of VH of P1-068761_E55A_E56N, and a VL comprising the amino acid sequence of VL of P1-068761_E55A_E56N;

[0232] (kk) a VH comprising the amino acid sequence of VH of P1-068761_E30D, and a VL comprising the amino acid sequence of VL of P1-068761_E30D;

[0233] (11) a VH comprising the amino acid sequence of VH of P1-068761_E30D_E55A, and a VL comprising the amino acid sequence of VL of P1-068761_E30D_E55A;

[0234] (mm) a VH comprising the amino acid sequence of VH of P1-068761_E56N_H100G, and a VL comprising the amino acid sequence of VL of P1-068761_E56N_H100G;

[0235] (nn) a VH comprising the amino acid sequence of VH of P1-068761_E30D_H100G, and a VL comprising the amino acid sequence of VL of P1-068761_E30D_H100G;

[0236] (oo) a VH comprising the amino acid sequence of VH of P1-068761_E30D_E56N, and a VL comprising the amino acid sequence of VL of P1-068761_E30D_E56N;

[0237] (pp) a VH comprising the amino acid sequence of VH of P1-068761_E100fF, and a VL comprising the amino acid sequence of VL of P1-068761_E100fF;

[0238] (qq) a VH comprising the amino acid sequence of VH of P1-068761_E55A_E100fF, and a VL comprising the amino acid sequence of VL of P1-068761_E55A_E100fF;

[0239] (rr) a VH comprising the amino acid sequence of VH of P1-068761_H100G_E100fF, and a VL comprising the amino acid sequence of VL of P1-068761_H100G_E100fF;

[0240] (ss) a VH comprising the amino acid sequence of VH of P1-068761_E30D_E100fF, and a VL comprising the amino acid sequence of VL of P1-068761_E30D_E100fF;

[0241] (tt) a VH comprising the amino acid sequence of VH of P1-068761_E56N_E100fF, and a VL comprising the amino acid sequence of VL of P1-068761_E56N_E100fF;

[0242] (uu) a VH comprising the amino acid sequence of VH of P1-068761_E32Y, and a VL comprising the amino acid sequence of VL of P1-068761_E32Y;

[0243] (vv) a VH comprising the amino acid sequence of VH of P1-068761_E32Y_E55A, and a VL comprising the amino acid sequence of VL of P1-068761_E32Y_E55A;

[0244] (ww) a VH comprising the amino acid sequence of VH of P1-068761_E32Y_E56N, and a VL comprising the amino acid sequence of VL of P1-068761_E32Y_E56N;

[0245] (xx) a VH comprising the amino acid sequence of VH of P1-068761_E30D_E32Y, and a VL comprising the amino acid sequence of VL of P1-068761_E30D_E32Y;

[0246] (yy) a VH comprising the amino acid sequence of VH of P1-068761_E32Y_H100G, and a VL comprising the amino acid sequence of VL of P1-068761_E32Y_H100G;

[0247] (zz) a VH comprising the amino acid sequence of VH of P1-068761_E32Y_E100fF, and a VL comprising the amino acid sequence of VL of P1-068761_E32Y_E100fF;

[0248] (aaa) a VH comprising the amino acid sequence of VH of P1-068767_D52N_D102V, and a VL comprising the amino acid sequence of VL of P1-068767_D52N_D102V;

[0249] (bbb) a VH comprising the amino acid sequence of VH of P1-068767_D52N, and a VL comprising the amino acid sequence of VL of P1-068767_D52N;

[0250] (ccc) a VH comprising the amino acid sequence of VH of P1-068767_D52N_E55A, and a VL comprising the amino acid sequence of VL of P1-068767_D52N_E55A;

[0251] (ddd) a VH comprising the amino acid sequence of VH of P1-068767_E55A_D102V, and a VL comprising the amino acid sequence of VL of P1-068767_E55A_D102V;

[0252] (eee) a VH comprising the amino acid sequence of VH of P1-068767_D102V, and a VL comprising the amino acid sequence of VL of P1-068767_D102V;

[0253] (fff) a VH comprising the amino acid sequence of VH of P1-068767_E55A, and a VL comprising the amino acid sequence of VL of P1-068767_E55A;

[0254] (ggg) a VH comprising the amino acid sequence of VH of P1-068767_E30D_D52N, and a VL comprising the amino acid sequence of VL of P1-068767_E30D_D52N;

[0255] (hhh) a VH comprising the amino acid sequence of VH of P1-068767_E30D_D102V, and a VL comprising the amino acid sequence of VL of P1-068767_E30D_D102V;

[0256] (iii) a VH comprising the amino acid sequence of VH of P1-068767_E30D, and a VL comprising the amino acid sequence of VL of P1-068767_E30D;

[0257] (jjj) a VH comprising the amino acid sequence of VH of P1-068767_E30D_E55A, and a VL comprising the amino acid sequence of VL of P1-068767_E30D_E55A;

[0258] (kkk) a VH comprising the amino acid sequence of VH of P1-068767_E100fF_D102V, and a VL comprising the amino acid sequence of VL of P1-068767_E100fF_D102V;

[0259] (111) a VH comprising the amino acid sequence of VH of P1-068767_E55A_E100fF, and a VL comprising the amino acid sequence of VL of P1-068767_E55A_E100fF;

[0260] (mmm) a VH comprising the amino acid sequence of VH of P1-068767_D52N_E100fF, and a VL comprising the amino acid sequence of VL of P1-068767_D52N_E100fF;

[0261] (nnn) a VH comprising the amino acid sequence of VH of P1-068767_E100fF, and a VL comprising the amino acid sequence of VL of P1-068767_E100fF; or

[0262] (ooo) a VH comprising the amino acid sequence of VH of P1-068767_E30D_E100fF, and a VL comprising the amino acid sequence of VL of P1-068767_E30D_E100fF;

[0263] (ppp) a VH comprising the amino acid sequence of VH of VISTA.4, and a VL comprising the VL of VISTA.4;

[0264] (qqq) a VH comprising the amino acid sequence of the VH of VISTA.4_VL_A64G, and a VL comprising the VL of VISTA.4_VL_A64G;

[0265] (rrr) a VH comprising the amino acid sequence of the VH of P1-070976, and a VL comprising VLP1-070976;

[0266] (sss) a VH comprising the amino acid sequence of VH of P1-071799, and a VL comprising the VL of P1-071799;

[0267] (ttt) a VH comprising the amino acid sequence of VH of P1-071801, and a VL comprising the VL of P1-071801;

[0268] (uuu) VH comprising the amino acid sequence of VH P1-065333, and VL comprising the VL of P1-065333.

[0269] Anti-hVISTA Abs may include:

[0270] (a) a VH comprising the VH CDRs of the VH of P1-061029 and a VL comprising the VL CDRs of P1-061029, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-061029;

[0271] (b) a VH comprising the VH CDRs of the VH of P1-061015 and a VL comprising the VL CDRs of P1-061015, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-061015;

[0272] (c) a VH comprising the VH CDRs of the VH of P1-068757 and a VL comprising the VL CDRs of P1-068757, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068757;

[0273] (d) a VH comprising the VH CDRs of the VH of P1-068759 and a VL comprising the VL CDRs of P1-068759, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068759;

[0274] (e) a VH comprising the VH CDRs of the VH of P1-068761 and a VL comprising the VL CDRs of P1-068761, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761;

[0275] (f) a VH comprising the VH CDRs of the VH of P1-068763 and a VL comprising the VL CDRs of P1-068763, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068763;

[0276] (g) a VH comprising the VH CDRs of the VH of P1-068765 and a VL comprising the VL CDRs of P1-068765, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068765;

[0277] (h) a VH comprising the VH CDRs of the VH of P1-068767 and a VL comprising the VL CDRs of P1-068767, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767;

[0278] (i) a VH comprising the VH CDRs of the VH of P1-068769 and a VL comprising the VL CDRs of P1-068769, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068769;

[0279] (j) a VH comprising the VH CDRs of the VH of P1-068771 and a VL comprising the VL CDRs of P1-068771, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068771;

[0280] (k) a VH comprising the VH CDRs of the VH of P1-068773 and a VL comprising the VL CDRs of P1-068773, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068773;

[0281] (l) a VH comprising the VH CDRs of the VH of P1-068775 and a VL comprising the VL CDRs of P1-068775, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068775;

[0282] (m) a VH comprising the VH CDRs of the VH of P1-069059 and a VL comprising the VL CDRs of P1-069059, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-069059;

[0283] (n) a VH comprising the VH CDRs of the VH of P1-069061 and a VL comprising the VL CDRs of P1-069061, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-069061;

[0284] (o) a VH comprising the VH CDRs of the VH of P1-069063 and a VL comprising the VL CDRs of P1-069063, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-069063;

[0285] (p) a VH comprising the VH CDRs of the VH of P1-069065 and a VL comprising the VL CDRs of P1-069065, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-069065;

[0286] (q) a VH comprising the VH CDRs of the VH of P1-069067 and a VL comprising the VL CDRs of P1-069067, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-069067;

[0287] (r) a VH comprising the VH CDRs of the VH of P1-069069 and a VL comprising the VL CDRs of P1-069069, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-069069;

[0288] (s) a VH comprising the VH CDRs of the VH of P1-069071 and a VL comprising the VL CDRs of P1-069071, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-069071;

[0289] (t) a VH comprising the VH CDRs of the VH of P1-069073 and a VL comprising the VL CDRs of P1-069073, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-069073;

[0290] (u) a VH comprising the VH CDRs of the VH of P1-069075 and a VL comprising the VL CDRs of P1-069075, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-069075;

[0291] (v) a VH comprising the VH CDRs of the VH of P1-069077 and a VL comprising the VL CDRs of P1-069077, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-069077;

[0292] (w) a VH comprising the VH CDRs of the VH of P1-068736 and a VL comprising the VL CDRs of P1-068736, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068736;

[0293] (x) a VH comprising the VH CDRs of the VH of P1-068738 and a VL comprising the VL CDRs of P1-068738, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068738;

[0294] (y) a VH comprising the VH CDRs of the VH of P1-068740 and a VL comprising the VL CDRs of P1-068740, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068740;

[0295] (z) a VH comprising the VH CDRs of the VH of P1-068742 and a VL comprising the VL CDRs of P1-068742, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068742;

[0296] (aa) a VH comprising the VH CDRs of the VH of P1-068744, and a VL comprising the VL CDRs of P1-068744, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068744;

[0297] (bb) a VH comprising the VH CDRs of the VH of P1-068746 and a VL comprising the VL CDRs of P1-068746, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068746;

[0298] (cc) a VH comprising the VH CDRs of the VH of P1-068748 and a VL comprising the VL CDRs of P1-068748, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068748;

[0299] (dd) a VH comprising the VH CDRs of the VH of P1-068750 and a VL comprising the VL CDRs of P1-068750, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068750;

[0300] (ee) a VH comprising the VH CDRs of the VH of P1-068752 and a VL comprising the VL CDRs of P1-068752, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068752;

[0301] (ff) a VH comprising the VH CDRs of the VH of P1-068754 and a VL comprising the VL CDRs of P1-068754, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068754;

[0302] (gg) a VH comprising the VH CDRs of the VH of P1-068761_E55A, and a VL comprising the VL CDRs of P1-068761_E55A, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E55A;

[0303] (hh) a VH comprising the VH CDRs of the VH of P1-068761_H100G, and a VL comprising the VL CDRs of P1-068761_H100G, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_H100G;

[0304] (ii) a VH comprising the VH CDRs of the VH of P1-068761_E56N and a VL comprising the VL CDRs of P1-068761_E56N, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E56N;

[0305] (jj) a VH comprising the VH CDRs of the VH of P1-068761_E55A_E56N, and a VL comprising the VL CDRs of P1-068761_E55A_E56N, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E55A_E56N;

[0306] (kk) a VH comprising the VH CDRs of the VH of P1-068761_E30D, and a VL comprising the VL CDRs of P1-068761_E30D, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E30D;

[0307] (ll) a VH comprising the VH CDRs of the VH of P1-068761_E30D_E55A and a VL comprising the VL CDRs of P1-068761_E30D_E55A, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E30D_E55A;

[0308] (mm) a VH comprising the VH CDRs of the VH of P1-068761_E56N_H100G, and a VL comprising the VL CDRs of P1-068761_E56N_H100G, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E56N_H100G;

[0309] (nn) a VH comprising the VH CDRs of the VH of P1-068761_E30D_H100G, and a VL comprising the VL CDRs of P1-068761_E30D_H100G, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E30D_H100G;

[0310] (oo) a VH comprising the VH CDRs of the VH of P1-068761_E30D_E56N, and a VL comprising the VL CDRs of P1-068761_E30D_E56N, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E30D_E56N;

[0311] (pp) a VH comprising the VH CDRs of the VH of P1-068761_E100fF and a VL comprising the VLCDRs of P1-068761_E100fF, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E100fF;

[0312] (qq) a VH comprising the VH CDRs of the VH of P1-068761_E55A_E100fF, and a VL comprising the VL CDRs of P1-068761_E55A_E100fF, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E55A_E100fF;

[0313] (rr) a VH comprising the VH CDRs of the VH of P1-068761_H100G_E100fF, and a VL comprising the VL CDRs of P1-068761_H100G_E100fF, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_H100G_E100fF;

[0314] (ss) a VH comprising the VH CDRs of the VH of P1-068761_E30D_E100fF, and a VL comprising the VL CDRs of P1-068761_E30D_E100fF, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E30D_E100fF;

[0315] (tt) a VH comprising the VH CDRs of the VH of P1-068761_E56N_E100fF, and a VL comprising the VL CDRs of P1-068761_E56N_E100fF, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E56N_E100fF;

[0316] (uu) a VH comprising the VH CDRs of the VH of P1-068761_E32Y, and a VL comprising the VL CDRs of P1-068761_E32Y, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E32Y;

[0317] (vv) a VH comprising the VH CDRs of the VH of P1-068761_E32Y_E55A, and a VL comprising the VL CDRs of P1-068761_E32Y_E55A, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E32Y_E55A;

[0318] (ww) a VH comprising the VH CDRs of the VH of P1-068761_E32Y_E56N, and a VL comprising the VL CDRs of P1-068761_E32Y_E56N, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E32Y_E56N;

[0319] (xx) a VH comprising the VH CDRs of the VH of P1-068761_E30D_E32Y and a VL comprising the VL CDRs of P1-068761_E30D_E32Y, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E30D_E32Y;

[0320] (yy) a VH comprising the VH CDRs of the VH of P1-068761_E32Y_H100G, and a VL comprising the VL CDRs of P1-068761_E32Y_H100G, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E32Y_H100G;

[0321] (zz) a VH comprising the VH CDRs of the VH of P1-068761_E32Y_E100fF, a VL comprising the VL CDRs of P1-068761_E32Y_E100fF, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068761_E32Y_E100fF;

[0322] (aaa) a VH comprising the VH CDRs of the VH of P1-068767_D52N_D102V, and a VL comprising the VL CDRs of P1-068767_D52N_D102V, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_D52N_D102V;

[0323] (bbb) a VH comprising the VH CDRs of the VH of P1-068767_D52N, and a VL comprising the VL CDRs of P1-068767_D52N, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_D52N;

[0324] (ccc) a VH comprising the VH CDRs of the VH of P1-068767_D52N_E55A, and a VL comprising the VL CDRs of P1-068767_D52N_E55A, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_D52N_E55A;

[0325] (ddd) a VH comprising the VH CDRs of the VH of P1-068767_E55A_D102V, and a VL comprising the VL CDRs of P1-068767_E55A_D102V, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_E55A_D102V;

[0326] (eee) a VH comprising the VH CDRs of the VH of P1-068767_D102V, and a VL comprising the VL CDRs of P1-068767_D102V, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_D102V;

[0327] (fff) a VH comprising the VH CDRs of the VH of P1-068767_E55A, and a VL comprising the VL CDRs of P1-068767_E55A, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_E55A;

[0328] (ggg) a VH comprising the VH CDRs of the VH of P1-068767_E30D_D52N, and a VL comprising the VL CDRs of P1-068767_E30D_D52N, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_E30D_D52N;

[0329] (hhh) a VH comprising the VH CDRs of the VH of P1-068767_E30D_D102V, and a VL comprising the VL CDRs of P1-068767_E30D_D102V, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_E30D_D102V;

[0330] (iii) a VH comprising the VH CDRs of the VH of P1-068767_E30D and a VL comprising the VL CDRs of P1-068767_E30D, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_E30D;

[0331] (jjj) a VH comprising the VH CDRs of the VH of P1-068767_E30D_E55A, and a VL comprising the VL CDRs of P1-068767_E30D_E55A, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_E30D_E55A;

[0332] (kkk) a VH comprising the VH CDRs of the VH of P1-068767_E100fF_D102V, and a VL comprising the VL CDRs of P1-068767_E100fF_D102V, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_E100fF_D102V;

[0333] (lll) a VH comprising the VH CDRs of the VH of P1-068767_E55A_E100fF and a VL comprising the VL CDRs of P1-068767_E55A_E100fF, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_E55A_E100fF;

[0334] (mmm) a VH comprising the VH CDRs of the VH of P1-068767_D52N_E100fF, and a VL comprising the VL CDRs of P1-068767_D52N_E100fF, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_D52N_E100fF;

[0335] (nnn) a VH comprising the VH CDRs of the VH of P1-068767_E100fF and a VL comprising the VLCDRs of P1-068767_E100fF, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_E100fF; or

[0336] (ooo) a VH comprising the VH CDRs of the VH of P1-068767_E30D_E100fF, and a VL comprising the VL CDRs of P1-068767_E30D_E100fF, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-068767_E30D_E100fF;

[0337] (ppp) a VH comprising the VH CDRs of the VH of VISTA.4 and a VL comprising the VL CDRs of VISTA.4, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of VISTA.4;

[0338] (qqq) a VH comprising the VH CDRs of the VH of VISTA.4_VL_A64G, and a VL comprising the VL CDRs of VISTA.4_VL_A64G, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of VISTA.4_VL_A64G;

[0339] (rrr) a VH comprising the VH CDRs of the VH of P1-070976 and a VL comprising the VL CDRs of P1-070976, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-070976;

[0340] (sss) a VH comprising the VH CDRs of the VH of P1-071799 and a VL comprising the VL CDRs of P1-071799, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-071799;

[0341] (ttt) a VH comprising the VH CDRs of the VH of P1-071801 and a VL comprising the VL CDRs of P1-071801, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-071801; or

[0342] (uuu) a VH comprising the VH CDRs of the VH of P1-065333 and a VL comprising the VL CDRs of P1-065333, and VH and VL amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the VH and VL of P1-071799.

[0343] Anti-hVISTA Abs may include:

[0344] (a) VH consisting of the amino acid sequence of VH of P1-061029 and VL consisting of VL of P1-061029;

[0345] (b) a VH consisting of the amino acid sequence of VH of P1-061015 and a VL consisting of VL of P1-061015;

[0346] (c) a VH consisting of the amino acid sequence of VH of P1-068757 and a VL consisting of VL of P1-068757;

[0347] (d) a VH consisting of the amino acid sequence of VH of P1-068759 and a VL consisting of VL of P1-068759;

[0348] (e) a VH consisting of the amino acid sequence of VH of P1-068761 and a VL consisting of VL of P1-068761;

[0349] (f) a VH consisting of the amino acid sequence of VH of P1-068763 and a VL consisting of VL of P1-068763;

[0350] (g) a VH consisting of the amino acid sequence of VH of P1-068765 and a VL consisting of VL of P1-068765;

[0351] (h) a VH consisting of the amino acid sequence of VH of P1-068767 and a VL consisting of VL of P1-068767;

[0352] (i) a VH consisting of the amino acid sequence of VH of P1-068769 and a VL consisting of VL of P1-068769;

[0353] (j) a VH consisting of the amino acid sequence of VH of P1-068771 and a VL consisting of VL of P1-068771;

[0354] (k) a VH consisting of the amino acid sequence of VH of P1-068773 and a VL consisting of VL of P1-068773;

[0355] (1) a VH consisting of the amino acid sequence of VH of P1-068775 and a VL consisting of VL of P1-068775;

[0356] (m) a VH consisting of the amino acid sequence of VH of P1-069059 and a VL consisting of VL of P1-069059;

[0357] (n) a VH consisting of the amino acid sequence of VH of P1-069061 and a VL consisting of VL of P1-069061;

[0358] (o) a VH consisting of the amino acid sequence of VH of P1-069063 and a VL consisting of VL of P1-069063;

[0359] (p) a VH consisting of the amino acid sequence of VH of P1-069065 and a VL consisting of VL of P1-069065;

[0360] (q) a VH consisting of the amino acid sequence of VH of P1-069067 and a VL consisting of VL of P1-069067;

[0361] (r) a VH consisting of the amino acid sequence of VH of P1-069069 and a VL consisting of VL of P1-069069;

[0362] (s) VH consisting of the amino acid sequence of VH of P1-069071 and VL consisting of VL of P1-069071;

[0363] (t) a VH consisting of the amino acid sequence of VH of P1-069073 and a VL consisting of VL of P1-069073;

[0364] (u) a VH consisting of the amino acid sequence of VH of P1-069075 and a VL consisting of VL of P1-069075;

[0365] (v) a VH consisting of the amino acid sequence of VH of P1-069077 and a VL consisting of VL of P1-069077;

[0366] (w) a VH consisting of the amino acid sequence of VH of P1-068736 and a VL consisting of VL of P1-068736;

[0367] (x) a VH consisting of the amino acid sequence of VH of P1-068738 and a VL consisting of VL of P1-068738;

[0368] (y) a VH consisting of the amino acid sequence of VH of P1-068740 and a VL consisting of VL of P1-068740;

[0369] (z) a VH consisting of the amino acid sequence of VH of P1-068742 and a VL consisting of VL of P1-068742;

[0370] (aa) VH consisting of the amino acid sequence of VH of P1-068744 and VL consisting of VL of P1-068744;

[0371] (bb) a VH consisting of the amino acid sequence of VH of P1-068746 and a VL consisting of VL of P1-068746;

[0372] (cc) a VH consisting of the amino acid sequence of VH of P1-068748 and a VL consisting of VL of P1-068748;

[0373] (dd) a VH consisting of the amino acid sequence of the VH of P1-068750 and a VL consisting of the VL of P1-068750;

[0374] (ee) a VH consisting of the amino acid sequence of VH of P1-068752 and a VL consisting of VL of P1-068752;

[0375] (ff) a VH consisting of the amino acid sequence of VH of P1-068754 and a VL consisting of VL of P1-068754;

[0376] (gg) a VH consisting of the amino acid sequence of the VH of P1-068761_E55A and a VL consisting of the amino acid sequence of the VL of P1-068761_E55A;

[0377] (hh) VH consisting of the amino acid sequence of VH of P1-068761_H100G and VL consisting of the amino acid sequence of VL of P1-068761_H100G;

[0378] (ii) a VH consisting of the amino acid sequence of VH of P1-068761_E56N and a VL consisting of the amino acid sequence of VL of P1-068761_E56N;

[0379] (jj) a VH consisting of the amino acid sequence of VH of P1-068761_E55A_E56N and a VL consisting of the amino acid sequence of VL of P1-068761_E55A_E56N;

[0380] (kk) VH consisting of the amino acid sequence of VH of P1-068761_E30D and VL consisting of the amino acid sequence of VL of P1-068761_E30D;

[0381] (11) a VH consisting of the amino acid sequence of VH of P1-068761_E30D_E55A and a VL consisting of the amino acid sequence of VL of P1-068761_E30D_E55A;

[0382] (mm) VH consisting of the amino acid sequence of VH of P1-068761_E56N_H100G and VL consisting of the amino acid sequence of VL of P1-068761_E56N_H100G;

[0383] (nn) a VH consisting of the amino acid sequence of VH of P1-068761_E30D_H100G and a VL consisting of the amino acid sequence of VL of P1-068761_E30D_H100G;

[0384] (oo) a VH consisting of the amino acid sequence of the VH of P1-068761_E30D_E56N and a VL consisting of the amino acid sequence of the VL of P1-068761_E30D_E56N;

[0385] (pp) a VH consisting of the amino acid sequence of VH of P1-068761_E100fF and a VL consisting of the amino acid sequence of VL of P1-068761_E100fF;

[0386] (qq) VH consisting of the amino acid sequence of VH of P1-068761_E55A_E100fF and VL consisting of the amino acid sequence of VL of P1-068761_E55A_E100fF;

[0387] (rr) a VH consisting of the amino acid sequence of the VH of P1-068761_H100G_E100fF and a VL consisting of the amino acid sequence of the VL of P1-068761_H100G_E100fF;

[0388] (ss) VH consisting of the amino acid sequence of VH of P1-068761_E30D_E100fF and VL consisting of the amino acid sequence of VL of P1-068761_E30D_E100fF;

[0389] (tt) a VH consisting of the amino acid sequence of VH of P1-068761_E56N_E100fF and a VL consisting of the amino acid sequence of VL of P1-068761_E56N_E100fF;

[0390] (uu) VH consisting of the amino acid sequence of VH of P1-068761_E32Y and VL consisting of the amino acid sequence of VL of P1-068761_E32Y;

[0391] (vv) a VH consisting of the amino acid sequence of VH of P1-068761_E32Y_E55A and a VL consisting of the amino acid sequence of VL of P1-068761_E32Y_E55A;

[0392] (ww) VH consisting of the amino acid sequence of VH of P1-068761_E32Y_E56N and VL consisting of the amino acid sequence of VL of P1-068761_E32Y_E56N;

[0393] (xx) a VH consisting of the amino acid sequence of VH of P1-068761_E30D_E32Y and a VL consisting of the amino acid sequence of VL of P1-068761_E30D_E32Y;

[0394] (yy) VH consisting of the amino acid sequence of VH of P1-068761_E32Y_H100G and VL consisting of the amino acid sequence of VL of P1-068761_E32Y_H100G;

[0395] (zz) a VH consisting of the amino acid sequence of the VH of P1-068761_E32Y_E100fF and a VL consisting of the amino acid sequence of the VL of P1-068761_E32Y_E100fF;

[0396] (aaa) VH consisting of the amino acid sequence of VH of P1-068767_D52N_D102V and VL consisting of the amino acid sequence of VL of P1-068767_D52N_D102V;

[0397] (bbb) a VH consisting of the amino acid sequence of the VH of P1-068767_D52N and a VL consisting of the amino acid sequence of the VL of P1-068767_D52N;

[0398] (ccc) a VH consisting of the amino acid sequence of the VH of P1-068767_D52N_E55A and a VL consisting of the amino acid sequence of the VL of P1-068767_D52N_E55A;

[0399] (ddd) a VH consisting of the amino acid sequence of the VH of P1-068767_E55A_D102V and a VL consisting of the amino acid sequence of the VL of P1-068767_E55A_D102V;

[0400] (eee) VH consisting of the amino acid sequence of VH of P1-068767_D102V and VL consisting of the amino acid sequence of VL of P1-068767_D102V;

[0401] (fff) a VH consisting of the amino acid sequence of VH of P1-068767_E55A and a VL consisting of the amino acid sequence of VL of P1-068767_E55A;

[0402] (ggg) a VH consisting of the amino acid sequence of the VH of P1-068767_E30D_D52N and a VL consisting of the amino acid sequence of the VL of P1-068767_E30D_D52N;

[0403] (hhh) VH consisting of the amino acid sequence of VH of P1-068767_E30D_D102V and VL consisting of the amino acid sequence of VL of P1-068767_E30D_D102V;

[0404] (iii) a VH consisting of the amino acid sequence of VH of P1-068767_E30D and a VL consisting of the amino acid sequence of VL of P1-068767_E30D;

[0405] (jjj) VH consisting of the amino acid sequence of VH of P1-068767_E30D_E55A and VL consisting of the amino acid sequence of VL of P1-068767_E30D_E55A;

[0406] (kkk) a VH consisting of the amino acid sequence of VH of P1-068767_E100fF_D102V and a VL consisting of the amino acid sequence of VL of P1-068767_E100fF_D102V;

[0407] (111) a VH consisting of the amino acid sequence of VH of P1-068767_E55A_E100fF and a VL consisting of the amino acid sequence of VL of P1-068767_E55A_E100fF;

[0408] (mmm) VH consisting of the amino acid sequence of VH of P1-068767_D52N_E100fF and VL consisting of the amino acid sequence of VL of P1-068767_D52N_E100fF;

[0409] (nnn) a VH consisting of the amino acid sequence of VH of P1-068767_E100fF and a VL consisting of the amino acid sequence of VL of P1-068767_E100fF; or

[0410] (ooo) a VH consisting of the amino acid sequence of the VH of P1-068767_E30D_E100fF and a VL consisting of the amino acid sequence of the VL of P1-068767_E30D_E100fF;

[0411] (ppp) VH consisting of the amino acid sequence of VH of VISTA.4 and VL consisting of VL of VISTA.4;

[0412] (qqq) VH consisting of the amino acid sequence of VH of VISTA.4_VL_A64G and VL consisting of VL of VISTA.4_VL_A64G;

[0413] (rrr) VH consisting of the amino acid sequence of VH of P1-070976 and VL consisting of VL of P1-070976;

[0414] (sss) VH consisting of the amino acid sequence of VH of P1-071799 and VL consisting of VL of P1-071799;

[0415] (ttt) a VH consisting of the amino acid sequence of VH of P1-071801 and a VL consisting of VL of P1-071801; or

[0416] (uuu) VH consisting of the amino acid sequence of VH of P1-065333 and VL consisting of VL of P1-065333.

[0417] In certain embodiments, an anti-VISTA Ab comprises any of the variable regions and / or variable region CDRs 1-3 of the antibodies described above and elsewhere herein, such as:

[0418] (1) one or more of the VH CDR1, CDR2, and CDR3 of:

[0419] (2) VH CDR1, CDR2, and CDR3 of:

[0420] (3) VH of the following:

[0421] (4) one or more of the VH CDR1, CDR2, and CDR3 and one or more of the VL CDR1, CDR2, and CDR3 of:

[0422] (5) the VH CDR1, CDR2 and CDR3 and the VL CDR1, CDR2 and CDR3 of:

[0423] or

[0424] (6) VH and VL of the following:

[0425] P1-061029、P1-068757、P1-068759、P1-068761、P1-068763、P1-068765、P1-068767、P1-068769、P1-068771、P1-068773、P1-068775、P1-069059、P1-069061、P1-069063、P1-069065、P1-069067、P1-069069、P1-069071、P1-069073、P1-069075、P1-069077、P1-061015、P1-068736、P1-068738、P1-068740、P1-068742、P1-068744、P1-068766、P1-068748、P1-068750、P1-068752P1-068754、P1-068761_E55A、P1-068761_H100G、P1-068761_E56N、P1-068761_E55A_E56N、P1-068761_E30D、P1-068761_E30D_E55A、P1-068761_E56N_H100G、P1-068761_E30D_H100G、P1-068761_E30D_E56N、P1-068761_E100fF、P1-068761_E55A_E100fF、P1-068761_H100G_E100fF、P1-068761_E30D_E100fF、P1-068761_E56N_E100fF、P1-068761_E32Y、P1-068761_E32Y_E55A、P1-068761_E32Y_E56N、P1-068761_E30D_E32Y、P1-068761_E32Y_H100G、P1-068761_E32Y_E100fF、P1-068767_D52N_D102V、P1-068767_D52N、P1-068767_D52N_E55A、P1-068767_E55A_D102V、P1-068767_D102V、P1-068767_E55A、P1-068767_E30D_D52N、P1-068767_E30D_D102V、P1-068767_E30D、P1-068767_E30D_E55A、P1-068767_E100fF_D102V、P1-068767_E55A_E100fF、P1-068767_D52N_E100fF、P1-068767_E100fF、P1-068767_E30D_E100fF,or a VISTA.4 (also referred to as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17; and an anti-VISTA Ab is also an IgG antibody, such as an IgG1, IgG2, IgG3, or IgG4 antibody or a modified form thereof as described in the following sections. In some embodiments, the constant region has effector function, and in some embodiments, the constant region has no effector. In certain embodiments, the constant region is the constant region of IgG1.3.

[0426] In certain embodiments, an anti-VISTA Ab comprises any of the variable regions and / or variable region CDRs 1-3 of the antibodies described above and elsewhere herein, such as:

[0427] (1) one or more of the VH CDR1, CDR2, and CDR3 of:

[0428] (2) VH CDR1, CDR2, and CDR3 of:

[0429] (3) VH of the following:

[0430] (4) one or more of the VH CDR1, CDR2, and CDR3 and one or more of the VL CDR1, CDR2, and CDR3 of:

[0431] (5) the VH CDR1, CDR2 and CDR3 and the VL CDR1, CDR2 and CDR3 of:

[0432] or

[0433] (6) VH and VL of the following:

[0434] P1-061029、P1-068757、P1-068759、P1-068761、P1-068763、P1-068765、P1-068767、P1-068769、P1-068771、P1-068773、P1-068775、P1-069059、P1-069061、P1-069063、P1-069065、P1-069067、P1-069069、P1-069071、P1-069073、P1-069075、P1-069077、P1-061015、P1-068736、P1-068738、P1-068740、P1-068742、P1-068744、P1-068766、P1-068748、P1-068750、P1-068752P1-068754、P1-068761_E55A、P1-068761_H100G、P1-068761_E56N、P1-068761_E55A_E56N、P1-068761_E30D、P1-068761_E30D_E55A、P1-068761_E56N_H100G、P1-068761_E30D_H100G、P1-068761_E30D_E56N、P1-068761_E100fF、P1-068761_E55A_E100fF、P1-068761_H100G_E100fF、P1-068761_E30D_E100fF、P1-068761_E56N_E100fF、P1-068761_E32Y、P1-068761_E32Y_E55A、P1-068761_E32Y_E56N、P1-068761_E30D_E32Y、P1-068761_E32Y_H100G、P1-068761_E32Y_E100fF、P1-068767_D52N_D102V、P1-068767_D52N、P1-068767_D52N_E55A、P1-068767_E55A_D102V、P1-068767_D102V、P1-068767_E55A、P1-068767_E30D_D52N、P1-068767_E30D_D102V、P1-068767_E30D、P1-068767_E30D_E55A、P1-068767_E100fF_D102V、P1-068767_E55A_E100fF、P1-068767_D52N_E100fF、P1-068767_E100fF、P1-068767_E30D_E100fF,or a VISTA.4 (also referred to as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17;

[0435] And also contain one or more of the following characteristics:

[0436] - specifically binds to hVISTA, e.g., the histidine-rich region of the ECD, or a polypeptide comprising amino acid residues 35-127 of SEQ ID NO: 2, at acidic pH, e.g., pH 6.0 or pH 6.5;

[0437] - does not have significant binding to hVISTA, e.g., the histidine-rich region of the ECD, or a polypeptide comprising amino acid residues 35-127 of SEQ ID NO: 2, at physiological pH or neutral pH, e.g., pH 7.4 or pH 7.0;

[0438] - specifically binds to cynomolgus monkey VISTA, e.g., the histidine-rich region of the ECD, at acidic pH, e.g., pH 6.0 or pH 6.5;

[0439] - has no significant binding to the histidine-rich region of cynomolgus monkey VISTA, e.g., the ECD, at physiological pH or neutral pH, e.g., pH 7.4 or pH 7.0;

[0440] - reduced binding to hVISTA-ECD having substitutions at one or more of the following amino acids relative to the hVISTA ECD having SEQ ID NO: 2: T35, Y37, K38, T39, Y41, R54, T61, F62, Q63, L65, H66, L67, H68, H69, F97, L115, V117, I119, H121, H122, S124, E125, R127;

[0441] - Cross-competes with P1-061029, P1-068761, P1-068767, and / or P1-061015 for binding to hVISTA;

[0442] - inhibiting the binding of hVISTA to human T cells expressing VISTA (e.g., naive or activated T cells) at acidic pH, e.g., pH 6.0 or pH 6.5;

[0443] - inhibiting the binding of hVISTA to PSGL-1 with or without sialyl Lewis X at acidic pH, e.g., pH 6.0 or pH 6.5 (e.g., inhibiting the interaction between H153 and H154 of hVISTA having SEQ ID NO: 1 and PSGL-1 tyrosines Y46 and Y48, wherein PSGL-1 has or does not have sialyl Lewis X, and wherein the tyrosine is preferably sulfotyrosine);

[0444] - a mean residence time (MRT) of at least 100, 200, 300, 350, 400, 450, 500, 600 or 700 hours (e.g., at least 350 hours) in cynomolgus monkeys, e.g., measured as described in the Examples;

[0445] - stimulating T cell activation by, for example, enhancing T cell proliferation; enhancing IFN-γ production by T cells; and / or stimulating T cell receptor-mediated NF-κB signaling;

[0446] -Inhibit VISTA-mediated cell:cell adhesion;

[0447] - specifically binds to hVISTA in a VISTA-expressing human tumor cell sample or inflamed human tissue sample;

[0448] - contacts hVISTA through one or more (e.g., at least 1 to 3, 1 to 5, 1 to 10, 5 to 10, 5 to 15, or all) energetically important contact residues Y37, T39, R54, F62, H66, V117, I119, or S124 as determined, e.g., using the yeast surface display and NGS assay described in Example 15; and wherein the numbering is that of mature hVISTA;

[0449] - binds to region 1 of hVISTA having SEQ ID NO: 1: 57 LGPVDKGHDVTF 68 (SEQ ID NO:498); Zone 2: 86 RRPIRNLTFQDL 97 (SEQ ID NO: 497); and region 3: 148 VVEIRHHHSEHRVHGAME 165 (SEQ ID NO: 499), and optionally wherein binding is strongest to region 2 as determined by MS-HDX as described in Example 18;

[0450] - binds to the histidine-rich beta-sheet extension of hVISTA as described, e.g., in the Examples, e.g., as determined by crystallography;

[0451] - as described in the Examples, e.g., as determined by crystallography, such as by hydrogen bonding contacts with (i) H121, H122, and / or H123 or (ii) H66, H68, H121, H122, and / or H123 of mature hVISTA (at a distance of 4.0 angstroms). or smaller);

[0452] - Contacts hVISTA via at least one or more glutamic acid, aspartic acid, or histidine residues located in VH CDR1, CDR2, or CDR3;

[0453] - Low or undetectable levels of TMDD;

[0454] - Low or undetectable levels of neutropenia; and

[0455] - Any additional features listed in the claims and / or examples.

[0456] In certain embodiments, the anti-hVISTA Ab comprises a heavy chain (HC) comprising the amino acid sequence of the heavy chain of any one of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises a heavy chain comprising the amino acid sequence of the heavy chain of P1-061029 or P1-061015 or a progeny thereof, as shown in the sequence listing below, comprising an IgG1.3 heavy chain constant region, such as P1-061029.IgG1.3 (SEQ ID NO:69), P1-068757.IgG1.3, P1-068759.IgG1.3, P1-068761.IgG1.3, P1-068763.IgG1.3, P1-068765.IgG1.3, P1-068767 .IgG1.3, P1-068769.IgG1.3, P1-068771.IgG1.3, P1-068773.IgG1.3, P1-068775.IgG1.3, P1-069059.IgG1.3, P1-06906 1.IgG1.3, P1-069063.IgG1.3, P1-069065.IgG1.3, P1-069067.IgG1.3, P1-069069.IgG1.3, P1-069071.IgG1.3, P1-0690 73.IgG1.3, P1-069075.IgG1.3, P1-069077.IgG1.3, P1-061015.IgG1.3, P1-068736.IgG1.3, P1-068738.IgG1.3, P1-0687 40.IgG1.3, P1-068742.IgG1.3, P1-068744.IgG1.3, P1-068766.IgG1.3, P1-068748.IgG1.3, P1-068750.IgG1.3, P1-068 752.IgG1.3, P1-068754.IgG1.3, P1-068761_E55A.IgG1.3, P1-068761_H100G.IgG1.3, P1-068761_E56N.IgG1.3, P1-0687 61_E55A_E56N.IgG1.3, P1-068761_E30D.IgG1.3, P1-068761_E30D_E55A.IgG1.3, P1-068761_E56N_H100G.IgG1.3, P1-0 68761_E30D_H100G.IgG1.3, P1-068761_E30D_E56N.IgG1.3, P1-068761_E100fF.IgG1.3, P1-068761_E55A_E100fF.IgG1.3. P1-068761_H100G_E100fF.IgG1.3, P1-068761_E30D_E100fF.IgG1.3, P1-068761_E56N_E100 fF.IgG1.3, P1-068761_E32Y.IgG1.3, P1-068761_E32Y_E55A.IgG1.3, P1-068761_E32Y_E56N.Ig G1.3, P1-068761_E30D_E32Y.IgG1.3, P1-068761_E32Y_H100G.IgG1.3, P1-068761_E32Y_E100f F.IgG1.3, P1-068767_D52N_D102V.IgG1.3, P1-068767_D52N.IgG1.3, P1-068767_D52N_E55A.Ig G1.3, P1-068767_E55A_D102V.IgG1.3, P1-068767_D102V.IgG1.3, P1-068767_E55A.IgG1.3, P1 -068767_E30D_D52N.IgG1.3, P1-068767_E30D_D102V.IgG1.3, P1-068767_E30D.IgG1.3, P1-068 767_E30D_E55A.IgG1.3, P1-068767_E100fF_D102V.IgG1.3, P1-068767_E55A_E100fF.IgG1.3, P1-068767_D52N_E100fF.IgG1.3, P1-068767_E100fF.IgG1.3, or P1-068767_E30D_E100fF.IgG1.3. In certain embodiments, the antibody comprises the following heavy chain amino acid sequence: a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or another antibody disclosed in Example 17, optionally comprising an IgG1.3 heavy chain constant region.

[0457] In certain embodiments, the anti-hVISTA Ab comprises a heavy chain comprising the amino acid sequence of the heavy chain of any of the anti-hVISTA Abs comprising an IgG1.3 heavy chain constant region provided herein, and the amino acid sequence of the light chain of any of the anti-hVISTA Abs provided herein. In certain embodiments, the anti-hVISTA Ab comprises a heavy chain comprising the amino acid sequence of the VH of P1-061029 or P1-061015 or a progeny thereof, comprising an IgG1.3 HC constant region, such as P1-061029.IgG1.3 (SEQ ID NO:69), P1-068757.IgG1.3, P1-068759.IgG1.3, P1-068761.IgG1.3, P1-068763.IgG1.3, P1-068765.IgG1.3, P1-06 8767.IgG1.3, P1-068769.IgG1.3, P1-068771.IgG1.3, P1-068773.IgG1.3, P1-068775.IgG1.3, P1-069059.IgG1.3, P 1-069061.IgG1.3, P1-069063.IgG1.3, P1-069065.IgG1.3, P1-069067.IgG1.3, P1-069069.IgG1.3, P1-069071.IgG1 .3. P1-069073.IgG1.3, P1-069075.IgG1.3, P1-069077.IgG1.3, P1-061015.IgG1.3, P1-068736.IgG1.3, P1-068738. IgG1.3, P1-068740.IgG1.3, P1-068742.IgG1.3, P1-068744.IgG1.3, P1-068766.IgG1.3, P1-068748.IgG1.3, P1-06 8750.IgG1.3, P1-068752.IgG1.3, P1-068754.IgG1.3, P1-068761_E55A.IgG1.3, P1-068761_H100G.IgG1.3, P1-0687 61_E56N.IgG1.3, P1-068761_E55A_E56N.IgG1.3, P1-068761_E30D.IgG1.3, P1-068761_E30D_E55A.IgG1.3, P1-0687 61_E56N_H100G.IgG1.3, P1-068761_E30D_H100G.IgG1.3, P1-068761_E30D_E56N.IgG1.3, P1-068761_E100fF.IgG1.3. P1-068761_E55A_E100fF.IgG1.3, P1-068761_H100G_E100fF.IgG1.3, P1-068761_E30D_E100fF.IgG1. 3. P1-068761_E56N_E100fF.IgG1.3, P1-068761_E32Y.IgG1.3, P1-068761_E32Y_E55A.IgG1.3, P1-068761 _E32Y_E56N.IgG1.3, P1-068761_E30D_E32Y.IgG1.3, P1-068761_E32Y_H100G.IgG1.3, P1-068761_E32Y_ E100fF.IgG1.3, P1-068767_D52N_D102V.IgG1.3, P1-068767_D52N.IgG1.3, P1-068767_D52N_E55A.IgG1. 3. P1-068767_E55A_D102V.IgG1.3, P1-068767_D102V.IgG1.3, P1-068767_E55A.IgG1.3, P1-068767_E30 D_D52N.IgG1.3, P1-068767_E30D_D102V.IgG1.3, P1-068767_E30D.IgG1.3, P1-068767_E30D_E55A.IgG1. 3, P1-068767_E100fF_D102V.IgG1.3, P1-068767_E55A_E100fF.IgG1.3, P1-068767_D52N_E100fF.IgG1.3, P1-068767_E100fF.IgG1.3, or P1-068767_E30D_E100fF.IgG1.3; and a light chain comprising the amino acid sequence of the light chain of P1-061029 or P1-061015. In certain embodiments, the antibody comprises a heavy chain of a VISTA.4 (also known as 41F11)-derived antibody described in Tables 22-30 of Example 17, such as VISTA.4, VISTA.4_VL_A64G, P1-070976 (VISTA.4 VH_T28P, Y50W, S55E, D95H, L96E, P97E, Y100E; VL_A64G), P1-071799 (P1-070976_VH_H95D), P1-071801 (P1-070976_VH_E97P), or P1-065333 (VISTA.4 VH_T28P, Y50W, S55E, L96E, Y100E; VL_A64G), or an IgG1-like antibody disclosed in Example 17.3. Another antibody of the same antibody, and the light chain of the same antibody.

[0458] Anti-hVISTA Abs may include:

[0459] (a) a heavy chain comprising the amino acid sequence of the heavy chain of P1-061029.IgG1.3 (SEQ ID NO: 69) and a light chain comprising the light chain amino acid sequence of P1-061029 (SEQ ID NO: 70);

[0460] (b) a heavy chain comprising the amino acid sequence of the heavy chain of P1-061015.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-061015;

[0461] (c) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068757.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068757;

[0462] (d) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068759.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068759;

[0463] (e) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761;

[0464] (f) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068763.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068763;

[0465] (g) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068765.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068765;

[0466] (h) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of P1-068767;

[0467] (i) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068769.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of P1-068769;

[0468] (j) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068771.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068771;

[0469] (k) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068773.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068773;

[0470] (l) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068775.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068775;

[0471] (m) a heavy chain comprising the amino acid sequence of the heavy chain of P1-069059.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-069059;

[0472] (n) a heavy chain comprising the amino acid sequence of the heavy chain of P1-069061.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-069061;

[0473] (o) a heavy chain comprising the amino acid sequence of the heavy chain of P1-069063.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-069063;

[0474] (p) a heavy chain comprising the amino acid sequence of the heavy chain of P1-069065.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-069065;

[0475] (q) a heavy chain comprising the amino acid sequence of the heavy chain of P1-069067.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-069067;

[0476] (r) a heavy chain comprising the amino acid sequence of the heavy chain of P1-069069.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-069069;

[0477] (s) a heavy chain comprising the amino acid sequence of the heavy chain of P1-069071.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-069071;

[0478] (t) a heavy chain comprising the amino acid sequence of the heavy chain of P1-069073.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-069073;

[0479] (u) a heavy chain comprising the amino acid sequence of the heavy chain of P1-069075.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-069075;

[0480] (v) a heavy chain comprising the amino acid sequence of the heavy chain of P1-069077.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of P1-069077;

[0481] (w) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068736.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068736;

[0482] (x) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068738.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068738;

[0483] (y) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068740.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of P1-068740;

[0484] (z) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068742.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068742;

[0485] (aa) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068744.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068744;

[0486] (bb) a heavy chain comprising the amino acid sequence of VH of P1-068746.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068746;

[0487] (cc) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068748.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of P1-068748;

[0488] (dd) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068750.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068750;

[0489] (ee) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068752.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068752;

[0490] (ff) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068754.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068754;

[0491] (gg) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E55A.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E55A;

[0492] (hh) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_H100G.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_H100G;

[0493] (ii) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E56N.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E56N;

[0494] (jj) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E55A_E56N.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E55A_E56N;

[0495] (kk) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E30D.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E30D;

[0496] (11) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E30D_E55A.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E30D_E55A;

[0497] (mm) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E56N_H100G.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E56N_H100G;

[0498] (nn) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E30D_H100G.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E30D_H100G;

[0499] (oo) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E30D_E56N.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E30D_E56N;

[0500] (pp) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E100fF.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E100fF;

[0501] (qq) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E55A_E100fF.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E55A_E100fF;

[0502] (rr) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_H100G_E100fF.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_H100G_E100fF;

[0503] (ss) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E30D_E100fF.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E30D_E100fF;

[0504] (tt) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E56N_E100fF.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E56N_E100fF;

[0505] (uu) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E32Y.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E32Y;

[0506] (vv) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E32Y_E55A.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E32Y_E55A;

[0507] (ww) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E32Y_E56N.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E32Y_E56N;

[0508] (xx) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E30D_E32Y.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E30D_E32Y;

[0509] (yy) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E32Y_H100G.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068761_E32Y_H100G;

[0510] (zz) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068761_E32Y_E100fF.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of P1-068761_E32Y_E100fF;

[0511] (aaa) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_D52N_D102V.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_D52N_D102V;

[0512] (bbb) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_D52N.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_D52N;

[0513] (ccc) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_D52N_E55A.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_D52N_E55A;

[0514] (ddd) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_E55A_D102V.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_E55A_D102V;

[0515] (eee) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_D102V.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_D102V;

[0516] (fff) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_E55A.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_E55A;

[0517] (ggg) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_E30D_D52N.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_E30D_D52N;

[0518] (hhh) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_E30D_D102V.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_E30D_D102V;

[0519] (iii) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_E30D.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_E30D;

[0520] (jjj) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_E30D_E55A.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_E30D_E55A;

[0521] (kkk) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_E100fF_D102V.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_E100fF_D102V;

[0522] (111) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_E55A_E100fF.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_E55A_E100fF;

[0523] (mmm) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_D52N_E100fF.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_D52N_E100fF;

[0524] (nnn) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_E100fF.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_E100fF;

[0525] (ooo) a heavy chain comprising the amino acid sequence of the heavy chain of P1-068767_E30D_E100fF.IgG1.3 and a light chain comprising the light chain amino acid sequence of P1-068767_E30D_E100fF;

[0526] (ppp) a heavy chain comprising the amino acid sequence of the heavy chain of VISTA.4.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of VISTA.4.IgG1.3;

[0527] (qqq) a heavy chain comprising the amino acid sequence of the heavy chain of VISTA.4_VL_A64G.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of VISTA.4_VL_A64G.IgG1.3;

[0528] (rrr) a heavy chain comprising the amino acid sequence of the heavy chain of P1-070976.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of P1-070976.IgG1.3;

[0529] (sss) a heavy chain comprising the amino acid sequence of the heavy chain of P1-071799.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of P1-071799.IgG1.3; or

[0530] (ttt) a heavy chain comprising the amino acid sequence of the heavy chain of P1-071801.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of P1-071801.IgG1.3;

[0531] (uuu) A heavy chain comprising the amino acid sequence of the heavy chain of P1-065333.IgG1.3 and a light chain comprising the amino acid sequence of the light chain of P1-065333.IgG1.3.

[0532] Anti-hVISTA Abs may include:

[0533] (a) a heavy chain (HC) comprising the HC CDRs of the HC of P1-061029 and a light chain (LC) comprising the LC CDRs of P1-061029, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-061029.IgG1.3, respectively;

[0534] (b) a HC comprising the HC CDRs of the HC of P1-061015 and a LC comprising the LC CDRs of P1-061015, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-061015.IgG1.3, respectively;

[0535] (c) a HC comprising the HC CDRs of the HC of P1-068757 and a LC comprising the LC CDRs of P1-068757, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068757.IgG1.3, respectively;

[0536] (d) a HC comprising the HC CDRs of the HC of P1-068759 and a LC comprising the LC CDRs of P1-068759, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068759.IgG1.3, respectively;

[0537] (e) a HC comprising the HC CDRs of the HC of P1-068761 and a LC comprising the LC CDRs of P1-068761, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761.IgG1.3, respectively;

[0538] (f) a HC comprising the HC CDRs of the HC of P1-068763 and a LC comprising the LC CDRs of P1-068763, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068763.IgG1.3, respectively;

[0539] (g) a HC comprising the HC CDRs of the HC of P1-068765 and a LC comprising the LC CDRs of P1-068765, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068765.IgG1.3, respectively;

[0540] (h) a HC comprising the HC CDRs of the HC of P1-068767 and a LC comprising the LC CDRs of P1-068767, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767.IgG1.3, respectively;

[0541] (i) a HC comprising the HC CDRs of the HC of P1-068769 and a LC comprising the LC CDRs of P1-068769, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068769.IgG1.3, respectively;

[0542] (j) a HC comprising the HC CDRs of the HC of P1-068771 and a LC comprising the LC CDRs of P1-068771, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068771.IgG1.3, respectively;

[0543] (k) a HC comprising the HC CDRs of the HC of P1-068773 and a LC comprising the LC CDRs of P1-068773, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068773.IgG1.3, respectively;

[0544] (l) a HC comprising the HC CDRs of the HC of P1-068775 and a LC comprising the LC CDRs of P1-068775, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068775.IgG1.3, respectively;

[0545] (m) a HC comprising the HC CDRs of the HC of P1-069059 and a LC comprising the LC CDRs of P1-069059, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-069059.IgG1.3, respectively;

[0546] (n) a HC comprising the HC CDRs of the HC of P1-069061 and a LC comprising the LC CDRs of P1-069061, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-069061.IgG1.3, respectively;

[0547] (o) a HC comprising the HC CDRs of the HC of P1-069063 and a LC comprising the LC CDRs of P1-069063, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-069063.IgG1.3, respectively;

[0548] (p) a HC comprising the HC CDRs of the HC of P1-069065 and a LC comprising the LC CDRs of P1-069065, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-069065.IgG1.3, respectively;

[0549] (q) a HC comprising the HC CDRs of the HC of P1-069067 and a LC comprising the LC CDRs of P1-069067, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-069067.IgG1.3, respectively;

[0550] (r) a HC comprising the HC CDRs of the HC of P1-069069 and a LC comprising the LC CDRs of P1-069069, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-069069.IgG1.3, respectively;

[0551] (s) a HC comprising the HC CDRs of the HC of P1-069071 and a LC comprising the LC CDRs of P1-069071, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-069071.IgG1.3, respectively;

[0552] (t) a HC comprising the HC CDRs of the HC of P1-069073 and a LC comprising the LC CDRs of P1-069073, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-069073.IgG1.3, respectively;

[0553] (u) a HC comprising the HC CDRs of the HC of P1-069075 and a LC comprising the LC CDRs of P1-069075, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-069075.IgG1.3, respectively;

[0554] (v) a HC comprising the HC CDRs of the HC of P1-069077 and a LC comprising the LC CDRs of P1-069077, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-069077.IgG1.3, respectively;

[0555] (w) a HC comprising the HC CDRs of the HC of P1-068736 and a LC comprising the LC CDRs of P1-068736, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068736.IgG1.3, respectively;

[0556] (x) a HC comprising the HC CDRs of the HC of P1-068738 and a LC comprising the LC CDRs of P1-068738, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068738.IgG1.3, respectively;

[0557] (y) a HC comprising the HC CDRs of the HC of P1-068740 and a LC comprising the LC CDRs of P1-068740, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068740.IgG1.3, respectively;

[0558] (z) a HC comprising the HC CDRs of the HC of P1-068742 and a LC comprising the LC CDRs of P1-068742, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068742.IgG1.3, respectively;

[0559] (aa) a HC comprising the HC CDRs of the HC of P1-068744, and a LC comprising the LC CDRs of P1-068744, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068744.IgG1.3, respectively;

[0560] (bb) a HC comprising the HC CDRs of the HC of P1-068746 and a LC comprising the LC CDRs of P1-068746, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068746.IgG1.3, respectively;

[0561] (cc) a HC comprising the HC CDRs of the HC of P1-068748, and a LC comprising the LC CDRs of P1-068748, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068748.IgG1.3, respectively;

[0562] (dd) a HC comprising the HC CDRs of the HC of P1-068750, and a LC comprising the LC CDRs of P1-068750, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068750.IgG1.3, respectively;

[0563] (ee) a HC comprising the HC CDRs of the HC of P1-068752, and a LC comprising the LC CDRs of P1-068752, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068752.IgG1.3, respectively;

[0564] (ff) a HC comprising the HC CDRs of the HC of P1-068754, and a LC comprising the LC CDRs of P1-068754, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068754.IgG1.3, respectively;

[0565] (gg) a HC comprising the HC CDRs of the HC of P1-068761_E55A.IgG1.3 and a LC comprising the LC CDRs of P1-068761_E55A, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E55A.IgG1.3, respectively;

[0566] (hh) a HC comprising the HC CDRs of the HC of P1-068761_H100G.IgG1.3, and a LC comprising the LC CDRs of P1-068761_H100G, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_H100G.IgG1.3, respectively;

[0567] (ii) a HC comprising the HC CDRs of the HC of P1-068761_E56N.IgG1.3 and a LC comprising the LC CDRs of P1-068761_E56N, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E56N.IgG1.3, respectively;

[0568] (jj) a HC comprising the HC CDRs of the HC of P1-068761_E55A_E56N.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E55A_E56N, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E55A_E56N.IgG1.3, respectively;

[0569] (kk) a HC comprising the HC CDRs of the HC of P1-068761_E30D.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E30D, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E30D.IgG1.3, respectively;

[0570] (ll) a HC comprising the HC CDRs of the HC of P1-068761_E30D_E55A.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E30D_E55A, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E30D_E55A.IgG1.3, respectively;

[0571] (mm) a HC comprising the HC CDRs of the HC of P1-068761_E56N_H100G.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E56N_H100G, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E56N_H100G.IgG1.3, respectively;

[0572] (nn) a HC comprising the HC CDRs of the HC of P1-068761_E30D_H100G.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E30D_H100G, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E30D_H100G.IgG1.3, respectively;

[0573] (oo) a HC comprising the HC CDRs of the HC of P1-068761_E30D_E56N.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E30D_E56N, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E30D_E56N.IgG1.3, respectively;

[0574] (pp) a HC comprising the HC CDRs of the HC of P1-068761_E100fF.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E100fF, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E100fF.IgG1.3, respectively;

[0575] (qq) a HC comprising the HC CDRs of the HC of P1-068761_E55A_E100fF.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E55A_E100fF, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E55A_E100fF.IgG1.3, respectively;

[0576] (rr) a HC comprising the HC CDRs of the HC of P1-068761_H100G_E100fF.IgG1.3, and a LC comprising the LC CDRs of P1-068761_H100G_E100fF, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_H100G_E100fF.IgG1.3, respectively;

[0577] (ss) a HC comprising the HC CDRs of the HC of P1-068761_E30D_E100fF.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E30D_E100fF, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E30D_E100fF.IgG1.3, respectively;

[0578] (tt) a HC comprising the HC CDRs of the HC of P1-068761_E56N_E100fF.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E56N_E100fF, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E56N_E100fF.IgG1.3, respectively;

[0579] (uu) a HC comprising the HC CDRs of the HC of P1-068761_E32Y.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E32Y, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E32Y.IgG1.3, respectively;

[0580] (vv) a HC comprising the HC CDRs of the HC of P1-068761_E32Y_E55A.IgG1.3 and a LC comprising the LC CDRs of P1-068761_E32Y_E55A, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E32Y_E55A.IgG1.3, respectively;

[0581] (ww) a HC comprising the HC CDRs of the HC of P1-068761_E32Y_E56N.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E32Y_E56N, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E32Y_E56N.IgG1.3, respectively;

[0582] (xx) a HC comprising the HC CDRs of the HC of P1-068761_E30D_E32Y.IgG1.3 and a LC comprising the LC CDRs of P1-068761_E30D_E32Y, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E30D_E32Y.IgG1.3, respectively;

[0583] (yy) a HC comprising the HC CDRs of the HC of P1-068761_E32Y_H100G.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E32Y_H100G, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E32Y_H100G.IgG1.3, respectively;

[0584] (zz) a HC comprising the HC CDRs of the HC of P1-068761_E32Y_E100fF.IgG1.3, and a LC comprising the LC CDRs of P1-068761_E32Y_E100fF, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068761_E32Y_E100fF.IgG1.3, respectively;

[0585] (aaa) a HC comprising the HC CDRs of the HC of P1-068767_D52N_D102V.IgG1.3, and a LC comprising the LC CDRs of P1-068767_D52N_D102V, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_D52N_D102V.IgG1.3, respectively;

[0586] (bbb) a HC comprising the HC CDRs of the HC of P1-068767_D52N.IgG1.3, and a LC comprising the LC CDRs of P1-068767_D52N, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_D52N.IgG1.3, respectively;

[0587] (ccc) a HC comprising the HC CDRs of the HC of P1-068767_D52N_E55A.IgG1.3, and a LC comprising the LC CDRs of P1-068767_D52N_E55A, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_D52N_E55A.IgG1.3, respectively;

[0588] (ddd) a HC comprising the HC CDRs of the HC of P1-068767_E55A_D102V.IgG1.3, and a LC comprising the LC CDRs of P1-068767_E55A_D102V, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_E55A_D102V.IgG1.3, respectively;

[0589] (eee) a HC comprising the HC CDRs of the HC of P1-068767_D102V.IgG1.3, and a LC comprising the LC CDRs of P1-068767_D102V, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_D102V.IgG1.3, respectively;

[0590] (fff) a HC comprising the HC CDRs of the HC of P1-068767_E55A.IgG1.3, and a LC comprising the LC CDRs of P1-068767_E55A, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_E55A.IgG1.3, respectively;

[0591] (ggg) a HC comprising the HC CDRs of the HC of P1-068767_E30D_D52N.IgG1.3, and a LC comprising the LC CDRs of P1-068767_E30D_D52N, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_E30D_D52N.IgG1.3, respectively;

[0592] (hhh) a HC comprising the HC CDRs of the HC of P1-068767_E30D_D102V.IgG1.3, and a LC comprising the LC CDRs of P1-068767_E30D_D102V, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_E30D_D102V.IgG1.3, respectively;

[0593] (iii) a HC comprising the HC CDRs of the HC of P1-068767_E30D.IgG1.3 and a LC comprising the LC CDRs of P1-068767_E30D, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_E30D.IgG1.3, respectively;

[0594] (jjj) a HC comprising the HC CDRs of the HC of P1-068767_E30D_E55A.IgG1.3, and a LC comprising the LC CDRs of P1-068767_E30D_E55A, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_E30D_E55A.IgG1.3, respectively;

[0595] (kkk) a HC comprising the HC CDRs of the HC of P1-068767_E100fF_D102V.IgG1.3, and a LC comprising the LC CDRs of P1-068767_E100fF_D102V, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_E100fF_D102V.IgG1.3, respectively;

[0596] (lll) a HC comprising the HC CDRs of the HC of P1-068767_E55A_E100fF.IgG1.3, and a LC comprising the LC CDRs of P1-068767_E55A_E100fF, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_E55A_E100fF.IgG1.3, respectively;

[0597] (mmm) a HC comprising the HC CDRs of the HC of P1-068767_D52N_E100fF.IgG1.3, and a LC comprising the LC CDRs of P1-068767_D52N_E100fF, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_D52N_E100fF.IgG1.3, respectively;

[0598] (nnn) a HC comprising the HC CDRs of the HC of P1-068767_E100fF.IgG1.3, and a LC comprising the LC CDRs of P1-068767_E100fF, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_E100fF.IgG1.3, respectively;

[0599] (ooo) a HC comprising the HC CDRs of the HC of P1-068767_E30D_E100fF.IgG1.3 and a LC comprising the LC CDRs of P1-068767_E30D_E100fF, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-068767_E30D_E100fF.IgG1.3, respectively

[0600] (ppp) a heavy chain (HC) comprising the HC CDRs of the HC of VISTA.4 and a light chain (LC) comprising the LC CDRs of VISTA.4, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of VISTA.4.IgG1.3, respectively;

[0601] (qqq) a heavy chain (HC) comprising the HC CDRs of the HC of VISTA.4_VL_A64G, and a light chain (LC) comprising the LC CDRs of VISTA.4_VL_A64G, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of VISTA.4_VL_A64G.IgG1.3, respectively;

[0602] (rrr) a heavy chain (HC) comprising the HC CDRs of the HC of P1-070976 and a light chain (LC) comprising the LC CDRs of P1-070976, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-070976.IgG1.3, respectively;

[0603] (sss) a heavy chain (HC) comprising the HC CDRs of the HC of P1-071799 and a light chain (LC) comprising the LC CDRs of P1-071799, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-071799.IgG1.3, respectively;

[0604] (ttt) a heavy chain (HC) comprising the HC CDRs of the HC of P1-071801, and a light chain (LC) comprising the LC CDRs of P1-071801, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the HC and LC of P1-071801.IgG1.3, respectively; or

[0605] (uuu) a heavy chain (HC) comprising the HC CDRs of the HC of P1-065333 and a light chain (LC) comprising the LC CDRs of P1-065333, and HC and LC amino acid sequences that are at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99% identical to the HC and LC of P1-065333.IgG1.3, respectively.

[0606] In some embodiments, an anti-hVISTA Ab may comprise:

[0607] (a) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-061029.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-061029;

[0608] (b) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-061015.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-061015;

[0609] (c) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068757.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068757;

[0610] (d) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068759.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068759;

[0611] (e) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761;

[0612] (f) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068763.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068763;

[0613] (g) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068765.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068765;

[0614] (h) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767;

[0615] (i) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068769.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068769;

[0616] (j) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068771.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068771;

[0617] (k) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068773.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068773;

[0618] (l) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068775.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068775;

[0619] (m) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-069059.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-069059;

[0620] (n) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-069061.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-069061;

[0621] (o) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-069063.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-069063;

[0622] (p) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-069065.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-069065;

[0623] (q) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-069067.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-069067;

[0624] (r) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-069069.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-069069;

[0625] (s) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-069071.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-069071;

[0626] (t) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-069073.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-069073;

[0627] (u) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-069075.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-069075;

[0628] (v) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-069077.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-069077;

[0629] (w) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068736 and a light chain consisting of the amino acid sequence of the light chain of P1-068736;

[0630] (x) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068738.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068738;

[0631] (y) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068740.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068740;

[0632] (z) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068742.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068742;

[0633] (aa) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068744.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068744;

[0634] (bb) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068746.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068746;

[0635] (cc) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068748.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068748;

[0636] (dd) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068750.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068750;

[0637] (ee) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068752.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068752;

[0638] (ff) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068754 and a light chain consisting of the amino acid sequence of the light chain of P1-068754;

[0639] (gg) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E55A.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E55A;

[0640] (hh) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_H100G.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_H100G;

[0641] (ii) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E56N.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E56N;

[0642] (jj) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E55A_E56N.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E55A_E56N;

[0643] (kk) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E30D.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E30D;

[0644] (11) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E30D_E55A.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E30D_E55A;

[0645] (mm) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E56N_H100G.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E56N_H100G;

[0646] (nn) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E30D_H100G.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E30D_H100G;

[0647] (oo) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E30D_E56N.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E30D_E56N;

[0648] (pp) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E100fF.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E100fF;

[0649] (qq) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E55A_E100fF.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E55A_E100fF;

[0650] (rr) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_H100G_E100fF.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_H100G_E100fF;

[0651] (ss) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E30D_E100fF.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E30D_E100fF;

[0652] (tt) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E56N_E100fF.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E56N_E100fF;

[0653] (uu) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E32Y.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E32Y;

[0654] (vv) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E32Y_E55A.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E32Y_E55A;

[0655] (ww) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E32Y_E56N.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E32Y_E56N;

[0656] (xx) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E30D_E32Y.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E30D_E32Y;

[0657] (yy) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E32Y_H100G.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E32Y_H100G;

[0658] (zz) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068761_E32Y_E100fF.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068761_E32Y_E100fF;

[0659] (aaa) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_D52N_D102V.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_D52N_D102V;

[0660] (bbb) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_D52N.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_D52N;

[0661] (ccc) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_D52N_E55A.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_D52N_E55A;

[0662] (ddd) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_E55A_D102V.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_E55A_D102V;

[0663] (eee) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_D102V.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_D102V;

[0664] (fff) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_E55A.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_E55A;

[0665] (ggg) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_E30D_D52N.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_E30D_D52N;

[0666] (hhh) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_E30D_D102V.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_E30D_D102V;

[0667] (iii) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_E30D.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_E30D;

[0668] (jjj) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_E30D_E55A.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_E30D_E55A;

[0669] (kkk) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_E100fF_D102V.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_E100fF_D102V;

[0670] (111) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_E55A_E100fF.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_E55A_E100fF;

[0671] (mmm) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_D52N_E100fF.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_D52N_E100fF;

[0672] (nnn) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_E100fF.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_E100fF;

[0673] (ooo) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-068767_E30D_E100fF.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-068767_E30D_E100fF;

[0674] (ppp) a heavy chain consisting of the amino acid sequence of the heavy chain of VISTA.4.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of VISTA.4;

[0675] (qqq) a heavy chain consisting of the amino acid sequence of the heavy chain of VISTA.4_VL_A64.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of VISTA.4_VL_A64;

[0676] (rrr) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-070976.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-070976;

[0677] (sss) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-071799.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-071799;

[0678] (ttt) a heavy chain consisting of the amino acid sequence of the heavy chain of P1-071801.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-071801; or

[0679] (uuu) A heavy chain consisting of the amino acid sequence of the heavy chain of P1-065333.IgG1.3 and a light chain consisting of the amino acid sequence of the light chain of P1-065333.

[0680] In some embodiments, the present invention encompasses an anti-VISTA mAb comprising:

[0681] A heavy chain consisting of the amino acid sequence of the heavy chain listed above (a) to (uuu) followed by a Lys residue; and

[0682] A light chain consisting of the light chain amino acid sequence listed above (a) to (uuu);

[0683] The heavy chain and light chain amino acid sequences are selected from the same antibody species listed in (a) to (uuu) above.

[0684] In some embodiments, an anti-hVISTA Ab may comprise a heavy chain amino acid sequence comprising the VH amino acid sequence of the antibody species herein, but relative to the IgG1.3 heavy chain constant region provided as the HC sequence in the sequence listing herein (and see SEQ ID NO: 163), the antibody may comprise a different heavy chain constant region sequence, such as the following: a human wild-type IgG1 constant region such as human IgG1 allotype f (IgG1f) (SEQ ID NO: 182), or a modified human IgG1 constant region such as IgG1.1f (SEQ ID NO: 183), or a modified human IgG1 constant region such as IgG1.P238K (SEQ ID NO: 184). Accordingly, embodiments of the present invention include anti-VISTA Abs comprising:

[0685] (a) a heavy chain comprising (i) the amino acid sequence of VH of P1-061029 (SEQ ID NO: 67) and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-061029 (SEQ ID NO: 70);

[0686] (b) a heavy chain comprising (i) the amino acid sequence of VH of P1-061015 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-061015;

[0687] (c) a heavy chain comprising (i) the amino acid sequence of VH of P1-068757 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068757;

[0688] (d) a heavy chain comprising (i) the amino acid sequence of VH of P1-068759 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068759;

[0689] (e) a heavy chain comprising (i) the amino acid sequence of VH of P1-068761 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761;

[0690] (f) a heavy chain comprising (i) the amino acid sequence of VH of P1-068763 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068763;

[0691] (g) a heavy chain comprising (i) the amino acid sequence of VH of P1-068765 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068765;

[0692] (h) a heavy chain comprising (i) the amino acid sequence of VH of P1-068767 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767;

[0693] (i) a heavy chain comprising (i) the amino acid sequence of VH of P1-068769 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068769;

[0694] (j) a heavy chain comprising (i) the amino acid sequence of VH of P1-068771 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068771;

[0695] (k) a heavy chain comprising (i) the amino acid sequence of VH of P1-068773 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068773;

[0696] (1) a heavy chain comprising (i) the amino acid sequence of VH of P1-068775 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068775;

[0697] (m) a heavy chain comprising (i) the amino acid sequence of VH of P1-069059 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-069059;

[0698] (n) a heavy chain comprising (i) the amino acid sequence of VH of P1-069061 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-069061;

[0699] (o) a heavy chain comprising (i) the amino acid sequence of VH of P1-069063 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-069063;

[0700] (p) a heavy chain comprising (i) the amino acid sequence of VH of P1-069065 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-069065;

[0701] (q) a heavy chain comprising (i) the amino acid sequence of VH of P1-069067 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-069067;

[0702] (r) a heavy chain comprising (i) the amino acid sequence of VH of P1-069069 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-069069;

[0703] (s) a heavy chain comprising (i) the amino acid sequence of VH of P1-069071 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-069071;

[0704] (t) a heavy chain comprising (i) the amino acid sequence of VH of P1-069073 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-069073;

[0705] (u) a heavy chain comprising (i) the amino acid sequence of VH of P1-069075 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-069075;

[0706] (v) a heavy chain comprising (i) the amino acid sequence of VH of P1-069077 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-069077;

[0707] (w) a heavy chain comprising (i) the amino acid sequence of VH of P1-068736 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068736;

[0708] (x) a heavy chain comprising (i) the amino acid sequence of VH of P1-068738 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068738;

[0709] (y) a heavy chain comprising (i) the amino acid sequence of VH of P1-068740 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068740;

[0710] (z) a heavy chain comprising (i) the amino acid sequence of VH of P1-068742 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068742;

[0711] (aa) a heavy chain comprising (i) the amino acid sequence of VH of P1-068744 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068744;

[0712] (bb) a heavy chain comprising (i) the amino acid sequence of VH of P1-068746 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068746;

[0713] (cc) a heavy chain comprising (i) the amino acid sequence of VH of P1-068748 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068748;

[0714] (dd) a heavy chain comprising (i) the amino acid sequence of VH of P1-068750 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068750;

[0715] (ee) a heavy chain comprising (i) the amino acid sequence of VH of P1-068752 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068752;

[0716] (ff) a heavy chain comprising (i) the amino acid sequence of VH of P1-068754 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068754;

[0717] (gg) a heavy chain comprising (i) the amino acid sequence of VH of P1-068761_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E55A;

[0718] (hh) a heavy chain comprising (i) the amino acid sequence of VH of P1-068761_H100G and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_H100G;

[0719] (ii) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E56N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E56N;

[0720] (jj) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E55A_E56N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E55A_E56N;

[0721] (kk) a heavy chain comprising (i) the amino acid sequence of VH of P1-068761_E30D and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E30D;

[0722] (ll) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E30D_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E30D_E55A;

[0723] (mm) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E56N_H100G and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E56N_H100G;

[0724] (nn) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E30D_H100G and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E30D_H100G;

[0725] (oo) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E30D_E56N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E30D_E56N;

[0726] (pp) a heavy chain comprising (i) the amino acid sequence of VH of P1-068761_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E100fF;

[0727] (qq) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E55A_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E55A_E100fF;

[0728] (rr) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_H100G_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_H100G_E100fF;

[0729] (ss) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E30D_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E30D_E100fF;

[0730] (tt) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E56N_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E56N_E100fF;

[0731] (uu) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E32Y and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E32Y;

[0732] (vv) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E32Y_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E32Y_E55A;

[0733] (ww) a heavy chain comprising the amino acid sequence of (i) VH of P1-068761_E32Y_E56N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E32Y_E56N;

[0734] (xx) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E30D_E32Y and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E30D_E32Y;

[0735] (yy) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E32Y_H100G and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E32Y_H100G;

[0736] (zz) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E32Y_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068761_E32Y_E100fF;

[0737] (aaa) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068767_D52N_D102V and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_D52N_D102V;

[0738] (bbb) a heavy chain comprising (i) the amino acid sequence of VH of P1-068767_D52N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_D52N;

[0739] (ccc) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068767_D52N_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_D52N_E55A;

[0740] (ddd) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068767_E55A_D102V and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_E55A_D102V;

[0741] (eee) a heavy chain comprising (i) the amino acid sequence of VH of P1-068767_D102V and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_D102V;

[0742] (fff) a heavy chain comprising (i) the amino acid sequence of VH of P1-068767_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_E55A;

[0743] (ggg) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068767_E30D_D52N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_E30D_D52N;

[0744] (hhh) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068767_E30D_D102V and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_E30D_D102V;

[0745] (iii) a heavy chain comprising the amino acid sequence of (i) VH of P1-068767_E30D and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_E30D;

[0746] (jjj) a heavy chain comprising (i) the amino acid sequence of VH of P1-068767_E30D_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_E30D_E55A;

[0747] (kkk) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068767_E100fF_D102V and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_E100fF_D102V;

[0748] (111) a heavy chain comprising (i) the amino acid sequence of VH of P1-068767_E55A_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_E55A_E100fF;

[0749] (mmm) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068767_D52N_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_D52N_E100fF;

[0750] (nnn) a heavy chain comprising (i) the amino acid sequence of VH of P1-068767_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_E100fF;

[0751] (ooo) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068767_E30D_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-068767_E30D_E100fF;

[0752] (ppp) a heavy chain comprising (i) the amino acid sequence of VH of VISTA.4 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of VISTA.4;

[0753] (qqq) a heavy chain comprising the amino acid sequence of (i) the VH of VISTA.4_VL_A64 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of VISTA.4_VL_A64;

[0754] (rrr) a heavy chain comprising (i) the amino acid sequence of VH of P1-070976 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-070976;

[0755] (sss) a heavy chain comprising (i) the amino acid sequence of VH of P1-071799 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-071799;

[0756] (ttt) a heavy chain comprising (i) the amino acid sequence of VH of P1-071801 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-071801; or

[0757] (uuu) a heavy chain comprising (i) the amino acid sequence of VH of P1-065333 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain comprising the light chain amino acid sequence of P1-065333.

[0758] Certain embodiments of the present disclosure include an anti-VISTA Ab comprising:

[0759] (a) a heavy chain consisting of (i) the amino acid sequence of VH of P1-061029 (SEQ ID NO: 67) and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-061029 (SEQ ID NO: 70);

[0760] (b) a heavy chain consisting of (i) the amino acid sequence of VH of P1-061015 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-061015;

[0761] (c) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068757 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068757;

[0762] (d) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068759 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068759;

[0763] (e) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761;

[0764] (f) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068763 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068763;

[0765] (g) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068765 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068765;

[0766] (h) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767;

[0767] (i) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068769 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068769;

[0768] (j) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068771 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068771;

[0769] (k) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068773 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068773;

[0770] (l) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068775 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068775;

[0771] (m) a heavy chain consisting of (i) the amino acid sequence of VH of P1-069059 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-069059;

[0772] (n) a heavy chain consisting of (i) the amino acid sequence of VH of P1-069061 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-069061;

[0773] (o) a heavy chain consisting of (i) the amino acid sequence of VH of P1-069063 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-069063;

[0774] (p) a heavy chain consisting of (i) the amino acid sequence of VH of P1-069065 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-069065;

[0775] (q) a heavy chain consisting of (i) the amino acid sequence of VH of P1-069067 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-069067;

[0776] (r) a heavy chain consisting of (i) the amino acid sequence of VH of P1-069069 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-069069;

[0777] (s) a heavy chain consisting of (i) the amino acid sequence of VH of P1-069071 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-069071;

[0778] (t) a heavy chain consisting of (i) the amino acid sequence of VH of P1-069073 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-069073;

[0779] (u) a heavy chain consisting of (i) the amino acid sequence of VH of P1-069075 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-069075;

[0780] (v) a heavy chain consisting of (i) the amino acid sequence of VH of P1-069077 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-069077;

[0781] (w) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068736 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068736;

[0782] (x) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068738 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068738;

[0783] (y) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068740 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068740;

[0784] (z) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068742 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068742;

[0785] (aa) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068744 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068744;

[0786] (bb) a heavy chain consisting of the amino acid sequence of VH of P1-068746 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068746;

[0787] (cc) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068748 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068748;

[0788] (dd) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068750 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068750;

[0789] (ee) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068752 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068752;

[0790] (ff) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068754 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068754;

[0791] (gg) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E55A;

[0792] (hh) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_H100G and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_H100G;

[0793] (ii) a heavy chain consisting of the amino acid sequence of (i) the VH of P1-068761_E56N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E56N;

[0794] (jj) a heavy chain consisting of the amino acid sequence of (i) the VH of P1-068761_E55A_E56N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E55A_E56N;

[0795] (kk) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_E30D and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E30D;

[0796] (ll) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_E30D_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E30D_E55A;

[0797] (mm) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_E56N_H100G and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E56N_H100G;

[0798] (nn) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_E30D_H100G and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E30D_H100G;

[0799] (oo) a heavy chain consisting of the amino acid sequence of (i) the VH of P1-068761_E30D_E56N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E30D_E56N;

[0800] (pp) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E100fF;

[0801] (qq) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_E55A_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E55A_E100fF;

[0802] (rr) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_H100G_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_H100G_E100fF;

[0803] (ss) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_E30D_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E30D_E100fF;

[0804] (tt) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_E56N_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E56N_E100fF;

[0805] (uu) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_E32Y and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E32Y;

[0806] (vv) a heavy chain consisting of the amino acid sequence of (i) the VH of P1-068761_E32Y_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E32Y_E55A;

[0807] (ww) a heavy chain consisting of the amino acid sequence of (i) the VH of P1-068761_E32Y_E56N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E32Y_E56N;

[0808] (xx) a heavy chain consisting of the amino acid sequence of (i) the VH of P1-068761_E30D_E32Y and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E30D_E32Y;

[0809] (yy) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068761_E32Y_H100G and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E32Y_H100G;

[0810] (zz) a heavy chain consisting of the amino acid sequence of (i) the VH of P1-068761_E32Y_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068761_E32Y_E100fF;

[0811] (aaa) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_D52N_D102V and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_D52N_D102V;

[0812] (bbb) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_D52N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_D52N;

[0813] (ccc) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_D52N_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_D52N_E55A;

[0814] (ddd) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_E55A_D102V and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_E55A_D102V;

[0815] (eee) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_D102V and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_D102V;

[0816] (fff) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_E55A;

[0817] (ggg) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_E30D_D52N and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_E30D_D52N;

[0818] (hhh) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_E30D_D102V and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_E30D_D102V;

[0819] (iii) a heavy chain consisting of the amino acid sequence of (i) the VH of P1-068767_E30D and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_E30D;

[0820] (jjj) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_E30D_E55A and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_E30D_E55A;

[0821] (kkk) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_E100fF_D102V and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_E100fF_D102V;

[0822] (111) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_E55A_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_E55A_E100fF;

[0823] (mmm) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_D52N_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_D52N_E100fF;

[0824] (nnn) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_E100fF;

[0825] (ooo) a heavy chain consisting of (i) the amino acid sequence of VH of P1-068767_E30D_E100fF and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-068767_E30D_E100fF,

[0826] (ppp) a heavy chain consisting of (i) the amino acid sequence of VH of VISTA.4 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of VISTA.4;

[0827] (qqq) a heavy chain consisting of (i) the amino acid sequence of VH of VISTA.4_VL_A64 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of VISTA.4_VL_A64;

[0828] (rrr) a heavy chain consisting of (i) the amino acid sequence of VH of P1-070976 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-070976;

[0829] (sss) a heavy chain consisting of (i) the amino acid sequence of VH of P1-071799 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-071799;

[0830] (ttt) a heavy chain consisting of (i) the amino acid sequence of VH of P1-071801 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-071801; or

[0831] (uuu) a heavy chain consisting of (i) the amino acid sequence of VH of P1-065333 and (ii) the amino acid sequence of SEQ ID NO: 182, and a light chain consisting of the light chain amino acid sequence of P1-065333,

[0832] The C-terminal amino acid of VH forms a peptide bond with the N-terminal amino acid of SEQ ID NO: 182.

[0833] In some embodiments, the present disclosure encompasses an anti-VISTA mAb comprising:

[0834] A heavy chain consisting of the following amino acid sequence: (i) VH of (a) to (uuu) listed above, (ii) SEQ ID NO: 182, and (iii) a Lys residue, wherein the C-terminal amino acid of VH forms a peptide bond with the N-terminal amino acid of SEQ ID NO: 182, and wherein the C-terminal amino acid of SEQ ID NO: 182 is linked to the N-terminus of Lys; and

[0835] A light chain consisting of the light chain amino acid sequence listed above (a) to (uuu);

[0836] The VH and light chain amino acid sequences are selected from the same antibody species listed in (a) to (uuu).

[0837] Certain embodiments of the present disclosure include an anti-VISTA Ab comprising:

[0838] (a) a heavy chain comprising (i) the amino acid sequence of VH of P1-061029 (SEQ ID NO: 67) and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-061029 (SEQ ID NO: 70);

[0839] (b) a heavy chain comprising (i) the amino acid sequence of VH of P1-061015 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-061015;

[0840] (c) a heavy chain comprising (i) the amino acid sequence of VH of P1-068757 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068757;

[0841] (d) a heavy chain comprising (i) the amino acid sequence of VH of P1-068759 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068759;

[0842] (e) a heavy chain comprising (i) the amino acid sequence of VH of P1-068761 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068761;

[0843] (f) a heavy chain comprising (i) the amino acid sequence of VH of P1-068763 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068763;

[0844] (g) a heavy chain comprising (i) the amino acid sequence of VH of P1-068765 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068765;

[0845] (h) a heavy chain comprising (i) the amino acid sequence of VH of P1-068767 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068767;

[0846] (i) a heavy chain comprising (i) the amino acid sequence of VH of P1-068769 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068769;

[0847] (j) a heavy chain comprising (i) the amino acid sequence of VH of P1-068771 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068771;

[0848] (k) a heavy chain comprising (i) the amino acid sequence of VH of P1-068773 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068773;

[0849] (1) a heavy chain comprising (i) the amino acid sequence of VH of P1-068775 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068775;

[0850] (m) a heavy chain comprising (i) the amino acid sequence of VH of P1-069059 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-069059;

[0851] (n) a heavy chain comprising (i) the amino acid sequence of VH of P1-069061 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-069061;

[0852] (o) a heavy chain comprising (i) the amino acid sequence of VH of P1-069063 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-069063;

[0853] (p) a heavy chain comprising (i) the amino acid sequence of VH of P1-069065 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-069065;

[0854] (q) a heavy chain comprising (i) the amino acid sequence of VH of P1-069067 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-069067;

[0855] (r) a heavy chain comprising (i) the amino acid sequence of VH of P1-069069 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-069069;

[0856] (s) a heavy chain comprising (i) the amino acid sequence of VH of P1-069071 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-069071;

[0857] (t) a heavy chain comprising (i) the amino acid sequence of VH of P1-069073 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-069073;

[0858] (u) a heavy chain comprising (i) the amino acid sequence of VH of P1-069075 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-069075;

[0859] (v) a heavy chain comprising (i) the amino acid sequence of VH of P1-069077 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-069077;

[0860] (w) a heavy chain comprising (i) the amino acid sequence of VH of P1-068736 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068736;

[0861] (x) a heavy chain comprising (i) the amino acid sequence of VH of P1-068738 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068738;

[0862] (y) a heavy chain comprising (i) the amino acid sequence of VH of P1-068740 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068740;

[0863] (z) a heavy chain comprising (i) the amino acid sequence of VH of P1-068742 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068742;

[0864] (aa) a heavy chain comprising (i) the amino acid sequence of VH of P1-068744 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068744;

[0865] (bb) a heavy chain comprising (i) the amino acid sequence of VH of P1-068746 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068746;

[0866] (cc) a heavy chain comprising (i) the amino acid sequence of VH of P1-068748 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068748;

[0867] (dd) a heavy chain comprising (i) the amino acid sequence of VH of P1-068750 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068750;

[0868] (ee) a heavy chain comprising (i) the amino acid sequence of VH of P1-068752 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068752;

[0869] (ff) a heavy chain comprising (i) the amino acid sequence of VH of P1-068754 and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068754;

[0870] (gg) a heavy chain comprising (i) the amino acid sequence of VH of P1-068761_E55A and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068761_E55A;

[0871] (hh) a heavy chain comprising (i) the amino acid sequence of VH of P1-068761_H100G and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid sequence of P1-068761_H100G;

[0872] (ii) a heavy chain comprising the amino acid sequence of (i) the VH of P1-068761_E56N and (ii) the amino acid sequence of SEQ ID NO: 183, and a light chain comprising the light chain amino acid se...

Claims

1. An antibody that specifically binds to human VISTA (hVISTA) under acidic conditions, wherein the antibody comprises a heavy chain and a light chain, wherein the heavy chain and the light chain contain VH CDR1, CDR2 and CDR3 and VL CDR1, CDR2 and CDR3 as shown in SEQ ID NOs: 509-511 and 500-502, respectively, or contain VH CDR1, CDR2 and CDR3 and VL CDR1, CDR2 and CDR3 as shown in SEQ ID NOs: 512-514 and 500-502, respectively, wherein the acidic conditions are conditions at a pH of 6.0 to 6.

5.

2. The antibody of claim 1, wherein the antibody comprises a VH comprising an amino acid sequence at least 90% identical to SEQ ID NO: 474 or SEQ ID NO: 477; wherein the antibody comprises a VL comprising an amino acid sequence that is at least 90% identical to SEQ ID NO: 493 or SEQ ID NO: 479; or wherein the antibody comprises a VH and a VL that are at least 90% identical to SEQ ID NOs: 474 and 479, SEQ ID NOs: 474 and 493, SEQ ID NOs: 477 and 479, or SEQ ID NOs: 477 and 493, respectively.

3. The antibody of claim 1, wherein the antibody comprises a VH as shown in SEQ ID NO: 474 or SEQ ID NO: 477; wherein the antibody comprises a VL as shown in SEQ ID NO: 493 or SEQ ID NO: 479; or wherein the antibody comprises a VH and a VL as shown in SEQ ID NOs: 474 and 479, SEQ ID NOs: 474 and 493, SEQ ID NOs: 477 and 479, or SEQ ID NOs: 477 and 493, respectively.

4. The antibody according to any one of claims 1 to 3, wherein the antibody comprises a heavy chain (HC) that is at least 90% identical to SEQ ID NO: 476 or SEQ ID NO: 480; wherein the antibody comprises a light chain (LC) that is at least 90% identical to SEQ ID NO: 494 or SEQ ID NO: 482; or wherein the antibody comprises a HC and a LC that are at least 90% identical to the HC and LC of SEQ ID NOs: 476 and 494, SEQ ID NOs: 476 and 482, SEQ ID NOs: 480 and 494, or SEQ ID NOs: 480 and 482, respectively.

5. The antibody according to any one of claims 1 to 3, wherein the antibody comprises the HC shown in SEQ ID NO: 476 or SEQ ID NO: 480; wherein the antibody comprises the LC shown in SEQ ID NO: 494 or SEQ ID NO: 482; or wherein the antibody comprises HC and LC as shown in SEQ ID NOs: 476 and 494, SEQ ID Nos: 476 and 482, SEQ ID NOs: 480 and 494, or SEQ ID Nos: 480 and 482, respectively.

6. an antibody that specifically binds to hVISTA and inhibits VISTA-mediated T cell activation, wherein the antibody comprises a heavy chain and a light chain, and the heavy chain and light chain contain VH CDR1, CDR2 and CDR3 and VL CDR1, CDR2 and CDR3 as shown in SEQ ID NO: 509-511 and 500-502, respectively, or contain VH CDR1, CDR2 and CDR3 and VL CDR1, CDR2 and CDR3 as shown in SEQ ID NO: 512-514 and 500-502, respectively.

7. The antibody of claim 6, wherein the antibody comprises a VH comprising an amino acid sequence that is at least 90% identical to the amino acid sequence shown in SEQ ID NO: 474 or 477; wherein the antibody comprises a VL comprising an amino acid sequence that is at least 90% identical to the amino acid sequence shown in SEQ ID NO: 493 or SEQ ID NO: 479; or wherein the antibody comprises a VH and a VL that are at least 90% identical to SEQ ID NOs: 474 and 479, SEQ ID NOs: 474 and 493, SEQ ID NOs: 477 and 479, or SEQ ID NOs: 477 and 493, respectively.

8. The antibody of claim 6, wherein the antibody comprises a VH as shown in SEQ ID NO: 474 or SEQ ID NO: 477; wherein the antibody comprises a VL comprising an amino acid sequence as shown in SEQ ID NO: 493 or 479; or wherein the antibody comprises a VH and a VL as shown in SEQ ID NOs: 474 and 479, SEQ ID NOs: 474 and 493, SEQ ID NOs: 477 and 479, or SEQ ID NOs: 477 and 493, respectively.

9. The antibody according to any one of claims 6 to 8, wherein the antibody comprises a heavy chain (HC) that is at least 90% identical to the heavy chain of SEQ ID NO: 476 or SEQ ID NO: 480; wherein the antibody comprises a light chain (LC) that is at least 90% identical to the light chain of SEQ ID NO: 494 or SEQ ID NO: 482; or wherein the antibody comprises a HC and a LC that are at least 90% identical to the HC and LC of SEQ ID NOs: 476 and 494, SEQ ID NOs: 476 and 482, SEQ ID NOs: 480 and 494, or SEQ ID NOs: 480 and 482, respectively.

10. The antibody according to any one of claims 6 to 8, wherein the antibody comprises the HC shown in SEQ ID NO: 476 or SEQ ID NO: 480; wherein the antibody comprises the LC shown in SEQ ID NO: 494 or SEQ ID NO: 482; or wherein the antibody comprises HC and LC as shown in SEQ ID NOs: 476 and 494, SEQ ID NOs: 476 and 482, SEQ ID NOs: 480 and 494, or SEQ ID NOs: 480 and 482, respectively.

11. The antibody according to any one of claims 1 to 3 or 6 to 8, comprising a heavy chain constant region comprising the amino acid sequence shown in SEQ ID NO: 163, SEQ ID NO: 182, wild-type IgG2, wild-type IgG3, wild-type IgG4, wild-type IgG4 comprising S228P, SEQ ID NO: 183, or SEQ ID NO: 184, wherein the heavy chain constant region has or does not have a C-terminal lysine.

12. The antibody according to any one of claims 1-3 or 6-8, comprising a HC comprising the amino acid sequence shown in SEQ ID NO: 476 or 480, and the HC may or may not comprise a signal peptide.

13. The antibody according to any one of claims 1-3 or 6-8, comprising a light chain comprising the amino acid sequence shown in SEQ ID NO: 482, 472 or 494, and the light chain comprising or not comprising a signal peptide.

14. The antibody according to claim 1-3 or 6-8, comprising a heavy chain and a light chain, wherein the heavy chain and the light chain comprise the amino acid sequence shown below: (a) SEQ ID NO: 476 and SEQ ID NO: 482, respectively; (b) SEQ ID NO: 476 and SEQ ID NO: 472, respectively; (c) SEQ ID NO: 476 and SEQ ID NO: 494, respectively; (d) SEQ ID NO: 480 and SEQ ID NO: 482, respectively; (e) SEQ ID NO: 480 and SEQ ID NO: 472, respectively; or (f) SEQ ID NO: 480 and SEQ ID NO: 494, respectively.

15. The antibody according to any one of claims 1 to 3 or 6 to 8, wherein the antibody has one or more of the following properties: (a) Specific binding to hVISTA under acidic conditions, but no significant binding under neutral or physiological conditions; (b) K binding to hVISTA under acidic conditions D than its K under neutral or physiological conditions D At least 10 times lower; (b) k of binding to hVISTA under acidic conditions off than its k under neutral or physiological conditions off At least 5 times lower; (d) Inhibition of hVISTA binding to human T cells at pH less than pH 7.0; Wherein acidic conditions are conditions at pH 6.0 to 6.5, wherein neutral conditions are conditions at pH 7, and wherein physiological conditions are conditions at pH 7.

4.

16. A nucleic acid or a set of at least two nucleic acids encoding the antibody according to any one of claims 1 to 15.

17. A cell comprising the nucleic acid of claim 16.

18. A method for producing an antibody, comprising culturing the cell according to claim 17 under conditions where the antibody is expressed.

19. A composition comprising the antibody, nucleic acid or cell according to any one of claims 1 to 17 and a pharmaceutically acceptable carrier.

20. Use of an antibody according to any one of claims 1 to 15 in the preparation of a medicament for treating a subject with colorectal cancer, wherein the medicament stimulates an immune response in the subject and / or wherein the antibody is a VISTA antagonist.

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