Polypeptides that bind to NKP46

Abstract

The present disclosure provides polypeptides that specifically bind to NKp46. In particular embodiments, the polypeptide may be a multispecific binding molecule that comprises a VHH domain, an antibody binding domain or a knob domain and at least one other binding domain, e.g., a binding domain recognizes a cancer antigen. A method of increasing binding between an NK cell and a cancer cell, a method of killing a cancer cell and a method of treatment that make use of the polypeptide or a polynucleotide encoding the same (e.g., an RNA) are also provided.

Description

[0001] Atty. Dkt: OMNI-002WO POLYPEPTIDES THAT BIND TO NKP46 CROSS-REFERENCINGThis application claims the benefit of provisional application serial no.63 / 613,034, filed on December 20, 2023, 63 / 666,374, filed on July 1, 2024, 63 / 687,275, filed on August 26, 2024, and 63 / 717,253, filed on November 6, 2024, which applications are incorporated by reference herein in their entireties. INCORPORATIONBYREFERENCEOFSEQUENCELISTINGPROVIDEDASA SEQUENCELISTINGXMLFILEA Sequence Listing is provided herewith as a Sequence Listing XML, “OMNI-002WO_SEQLIST.xml” created on December 18, 2024 and having a size of 2,004,172 bytes. The contents of the Sequence Listing XML are incorporated by reference herein in their entirety. BACKGROUNDNKp46 is a natural cytotoxicity receptor expressed on most or all mature NK (natural killer) cells. NK cells can be weakly activated by engagement of NKp46 alone. However, co-stimulation of NKp46 and other activating co-receptors (particularly 2B4, DNAM1, or CD2) enhances NK cell activation greatly. NKp46 does not appear to be downregulated in tumor-infiltrated NK cells in several cancers (e.g., lung carcinoma, acute myeloid leukemia and breast cancer) and, as such, NKp46 may be a promising target for an NK cell engager (NKCE), such as a BiKE (bispecific killer cell engager) or TriKE (bispecific killer cell engager). NKCEs hold NK and cancer cells together and activate the NK cells while they are attached to the cancer cells. NK cells can also attack virally-infected cells. There is a need for new polypeptides that specifically recognize NKp46. SUMMARY The present disclosure provides a polypeptide comprising a VHH domain comprising: (a) CDR1, CDR2 and CDR3 regions that are identical to the CDR1, CDR2 and CDR3 regions of a VHH antibody selected from Tables 1 and 10; or (b) CDR1, CDR2 and CDR3 regions that are otherwise identical to the CDR1, CDR2 and CDR3 regions of a VHH antibody selected from Tables 1 and 10 except for up to 10 amino acid substitutions in the collective CDR regions. In these embodiments, the VHH domain binds to NKp46. Atty. Dkt: OMNI-002WO The present disclosure also provides a polypeptide comprising: an antibody binding domain comprising: (i) a heavy chain variable domain comprising CDR1, CDR2 and CDR3 regions that are identical to the heavy chain CDR1, CDR2 and CDR3 regions of a common light chain antibody selected from Table 3 or 6 or are otherwise identical to the heavy chain CDR1, CDR2 and CDR3 regions of a common light chain antibody selected from Table 3 or 6 except for up to 10 amino acid substitutions in the collective CDR regions; and (ii) a light chain variable domain comprising CDR1, CDR2 and CDR3 regions that are identical to the light chain CDR1, CDR2 and CDR3 regions of the selected common light chain antibody or are otherwise identical to the light chain CDR1, CDR2 and CDR3 regions of the selected common light chain antibody except for up to 10 amino acid substitutions in the collective CDR regions, wherein the antibody binding domain binds to NKp46. The present disclosure also provides a polypeptide comprising a knob domain comprising an amino acid sequence that is the same as or comprises up to 10 amino acid substitutions relative to the knob domain of an ultralong CDR3 domain selected from Table 9. In some embodiments, the polypeptide comprises an amino acid sequence that is at least 90% (e.g., at least 95%) identical to the amino acid sequence of the selected VHH antibody, common light chain antibody or ultralong CDR3 domain. In some embodiments, the polypeptide may be a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain, e.g., a binding domain that recognizes a cancer antigen. In these embodiments, the polypeptide may be a bispecific binding molecule that comprises (i) the VHH domain, the antibody binding domain or the knob domain (each of which binds to NKp46) and (ii) a binding domain that recognizes a first antigen found on the surface of cancer cells or a trispecific binding molecule that comprises (i) the VHH domain, the antibody binding domain or the knob domain (each of which binds to NKp46), (ii) a binding domain that recognizes a first antigen on the surface of cancer cells and (iii) either a binding domain that recognizes a co-stimulatory receptor or a binding domain that recognizes a second antigen on the surface of cancer cells. Methods of increasing binding between an NK cell and a cancer cell, killing a cancer cell, and treating a cancer that make use of the polypeptide are also provided. In some embodiments, the polypeptide contains a VHH domain based on a VHH antibody selected from Tables 1 and 10. The antibodies of Tables 1 and 10 are from chicken and, as such, can potentially bind to epitopes in NKp46 that are in a variety of mammals, such as humans, mice and monkeys. Those epitopes should not be immunogenic in mammals (since they are already present) and, having been made by chickens, at least some of the present VHH domains are believed to bind to new Atty. Dkt: OMNI-002WO epitopes, at least relative to antibodies that are raised in a mammal. These antibodies may activate the NK cells more efficiently or have other advantages. Moreover, because the VHH domains are expected to bind to NKp46 from multiple mammals, the present polypeptide may be advantageous because its therapeutic potential can be readily tested in mammalian model systems for cancer (e.g., mice). In other embodiments, the polypeptide may contain heavy and light chain sequences based on a common light chain antibody of Table 3 or 6. In these cases, multispecific embodiments of the polypeptide may have a common light chain. In other embodiments, the polypeptide may contain a knob domain based on a sequence of Table 9. BRIEFDESCRIPTION OF THEDRAWINGSFIG.1 shows a schematic of the VHH3 transgene design. The endogenous chicken heavy chain locus (top line) was genetically modified in a series of steps in chicken primordial germ cells (PGCs). First, the germline V-D-J genes were deleted by gene targeting in two steps34-35. In the targeting steps, loxP sites and selectable markers were inserted into the locus (middle line), including an attP site for insertion of an attB-bearing plasmid by phiC31 integrase, with a promoter-less neo gene (in reverse orientation relative to the locus). Upon insertion of the VHH3 transgene, a β-actin promoter on the incoming plasmid (not shown) activated the neo gene, allowing for G418-selection of transfectants. PGCs carrying the VHH3 insertion and selectable markers were injected into embryos to produce germline chimeras. Chimeric males producing germline progeny were bred to Cre-expressing females to remove the selectable markers, resulting in the structure on the bottom line, with the VHH3 functional gene, 14 pseudogenes and intervening sequences properly positioned to express and splice to the downstream chicken constant regions. The chicken VH pseudogenes remain upstream. Schematics are not to scale. Abbreviations: cVH, chicken VH gene; D, chicken diversity gene segments; cJH, chicken JH gene; Pseudo cVH, chicken VH pseudogenes; B-act-GFP, chicken β-actin promoter driving the EGFP gene; CAG-puro, CAG promoter (chicken β-actin promoter with CMV enhancer) driving the puromycin resistance gene; neo, promoterless neomycin resistance gene. FIGS.2A-2G: Transgenic bird evaluations for B-cell development and subsequent antibody discovery. Total circulating IgM or IgY titer (Fig.2A) of different versions of the transgenes (VHH3 / IgL- / - or VHH / tLCi) was compared to wild-type (WT) chicken based on plasma ELISA. Transgenic chickens exhibited only IgM antibodies, with no IgY isotype switching / expression. Flow cytometric analysis (Fig.2B) of PBMCs with immunostaining for chicken B-cells (Bu1), CH1-domain-specific IgM Atty. Dkt: OMNI-002WO (IgM), polyclonal IgM (IgM poly), light chain (IgL), the VHH3 transgene (VHH), and T-cell receptor staining controls (TCR1 and TCR2 / 3). Transgenic chickens presented with a reduced population of B- cells, IgM antibody expressed without CH1 domain, no light chain, but positively expressing the VHH3 transgene. Gel electrophoresis image (Fig.2C) of PBMC RT-PCR product showed a reduced size IgM after amplification, as compared to the wild-type chicken. Light chain mRNA was not observed in the VHH3 / IgL - / - genotype, while a reduced-sized light chain was observed in the VHH3 / tLCi genotype. Western blot (Fig.2D) of plasma samples for verification of IgM or VHH3 transgene protein expression exhibited a reduced-sized IgM (no CH1) and positive expression for the VHH3 transgene protein, as compared to the protein weight of the wild-type which expressed full-size IgM and no VHH3. A subset of OmnidAb chickens were immunized with either NKp46 extracellular domain protein or progranulin (PGRN) protein to verify immuno-responsiveness to immunization and development of candidate monoclonal antibodies. Antigen-specific immune responses (Fig.2E) were evaluated from plasma samples by ELISA. The pre-immune (PI) titer and final draw (FD) titers are presented against their respective antigen target used in immunizations or a His-tag control target. No background binding to the target antigen was observed in the PI samples. FD samples exhibited strong binding to their respective target antigen and no binding to the His-tag control antigens. A select group of NKp46- binding clones were screened for binding to native protein (transfected CHO-K1 cells) via flow cytometry (Fig.2F), showing mean fluorescence intensity (MFI) binding to the NKp46-expressing CHO cells and minimal binding to the non-transfected parental CHO cells. A commercially-purchased mouse anti-NKp46 antibody was used as a biological positive control. A select group of NKp46-binding clones was also screened for functional ability (Fig.2G) to induce IFNγ release from primary NK-cells in cell culture, with two clones exhibiting a significant ability to induce IFNγ as compared to the media-control threshold. Ionomycin served as an ionophore positive control. The isotype control antibody was a non- binding IgG1antibody, matching the experimental samples’ antibody isotype. Reference antibodies NKp46-1, -2 and -3 were published NKp46 antibodies. FIGS.3A-3B. Sequence analysis of antigen-specific HcAbs. Mutational frequences in the anti- PGRN and anti-NKp46 VH regions were calculated and compared to the frequencies of potential donor residues in the pseudogene pool. VH sequences to PGRN (38 clones) or NKp46 (128 clones) were aligned to the germline VHH3 sequence and mutational frequencies at each position are shown in a WebLogo plot. Fig.3A shows data for NKp46. The top plot shows the results for the antibody clones, and the lower plot shows the same analysis for the pseudogene sequences in the VHH3 construct for comparison. The location of the stabilizing framework changes in the VHH3 functional gene (relative to Atty. Dkt: OMNI-002WO the human VH3-23 gene) are indicated by asterisks under the top logo plot. The usage frequency of gene conversion (FIG.3B) anti-NKp46 HcAb clones by each pseudogene in the VHH3 construct is shown. Identification of gene conversion and its pseudogene source was first performed. For each pseudogene, the percentage of HcAb clones in which the pseudogene CDRs were utilized to mutate the clones was then calculated. Clones and CDRs in which gene conversion was not identified or where gene conversion was identified but the pseudogene was ambiguous were not included. Gene conversion by the three CDRs is shown in a different color as indicated. Examples of gene conversion by each individual pseudogene CDR were found. The reference VHH3 sequence is SEQ ID NO: 2197. FIG 4: Gene conversion in CDRs. Gene conversion tracts in the CDRs of anti-NKp46 HcAb clones were mapped to their pseudogene source. For each clone shown, the CDRs are represented by lines, with a box to indicate position and approximate length of each gene conversion tract. The numbers in the boxes indicate the identifier number of the pseudogene that donated sequence. Tracts with two or more numbers indicate that the pseudogene could not be unambiguously assigned and any of the listed pseudogenes could have donated the sequence. Only the CDRs are shown since the VHH3 construct pseudogenes contain no diversity in the FRs and thus gene conversion is only observable in the CDRs. CDRs with no boxes did not have recognizable gene conversion, but all CDRs did show mutation from the germline VHH3 sequence. Somatic hypermutation and point mutations are not shown in the diagrams. Representative clones from different lineages are shown. FIG.5: Immunogenicity Plot. In silico evaluation of immunogenicity was performed on a random subset of OMNIDAB® heavy chain only molecules with antibody sequences analyzed as overlapping 9-mer segments and screened with EpiVax software for the presence of Class II-restricted HLA ligands and putative T-cell epitopes to calculate binding potential. Tregitope-adjusted EpiMatrix scores <-15 are considered to have low predicted immunogenicity and scores <-30 are considered minimal immunogenicity. A JanusMatrix Human Homology score for putative T-cell epitopes >5 suggests reduced immunogenic potential. FIGS.6A-6B: Kinetic and affinity determinations for anti-PGRN and anti-NKp46 OmnidAb clones. Scatter plot showing affinity distribution (FIG.6A) with highest, median, and lowest affinities indicated. Global fits showing diverse kinetic profiles (FIG.6B) for high, medium, and weak affinities (KDvalues reported on plots) of select NKp46 clones. Measured data are shown in blue-green with global fits overlaid in red. Atty. Dkt: OMNI-002WO FIGS.7A-7C. Developability assessment of antibody clones. Differential scanning fluorimetry analysis was performed on the selected anti-PGRN (FIG.7A) and anti-NKp46 (FIG.7B) OmnidAb antibodies in sdAb-Fc format that showed high melting temperature (Tm) and aggregation temperature (Tagg). AC-SINS was performed to assess self-association for the selected anti-PGRN and anti-NKp46 clones (FIG.7C), with the positive reference (ficlatuzumab, veltuzumab, and trastuzumab) and negative reference (bococizumab and duligotuzumab) IgG antibodies with known low and high AC-SINS values, respectively3233.The FDA-approved VHH-Fc antibody caplacizumab was also included as a reference for the sdAb-Fc format. FIG.8: Pseudogene sequence alignment. The VHH3 transgene contains one functional, expressed variable region (VHH3, top line) and 14 pseudogenes (P-VHH aligned below). The alignment includes a human VH3-23 / D / JH4 variable region (second line) for comparison, in order to indicate the locations of the stabilizing framework mutations. These mutations can be found in camelid VHH domains and contribute to their overall stability and solubility. Changes relative to the VHH3 reference sequence are colored. The frameworks in the pseudogenes all match the functional VHH3 sequence, whereas the CDRs are diverse sequences derived from human germline VH3 family genes (for CDR1 and 2) or from human-derived somatic sequences (CDR3). The pseudogenes are in the order they are found in the transgene, with P-VHH-15 the most proximal to VHH3 and P-VHH-28 the most distal. From top to bottom: SEQ ID NOS 2196-2211. FIG.9. Grand average of hydropathy (GRAVY) calculations for the FRs and CDRs in anti- NKp46 HcAbs. The GRAVY value for each germline FR or CDR is indicated by the vertical dotted line. The negative and positive values represent hydrophilic and hydrophobic values of FRs, respectively. The GRAVY values of the VH regions are plotted as frequencies. CDRs showed much more variation and tendency toward increasing hydrophilicity whereas FRs showed less variability, consistent with the patterns of diversity shown in Figure 3. FIGS.10A-10B. CDR3 lengths. CDR3 lengths in anti-PGRN and anti-NKp46 OmnidAb antibodies were plotted (FIG.10A), showing the percentage of clones in each set that had the lengths indicated on the X-axis. The germline length is 17 amino acids (AA), and about half of the antigen- specific clones retained this length, with variation to both shorter and longer lengths. For the PGRN clones, one group of 10 clones contained a length of 9 AA. These clones all target subdomain p and are Atty. Dkt: OMNI-002WO grouped together on the tree and some have high affinity. For comparison, the CDR3 lengths in the pseudogenes were plotted (FIG.10B). Most of the pseudogenes had CDR3 lengths longer than the 17 AA in the functional VHH3 gene. FIGS.11A and 11B. Analytical size-exclusion chromatography (aSEC) profiles. 17 anti- NKp46 OmnidAb antibodies were purified and aSEC was performed, confirming monomeric and homogeneous peaks. No aggregation peak was observed. In the aSEC profiles, y-axis mAu corresponds to milliabsorbance units. FIGS.12A-12D. Shows capture kinetic data to NKp46. Schematics of two types of capture approaches are shown – a standard anti-human Fc capture approach (FIG.12A) and a tethered (sandwich) approach (FIG.12B) for use in affinity determinations of bispecific antibodies from anti- NKp46 OmnidAb and OMNICLIC® common light chain clones. Global fits showing diverse kinetic profiles for select bispecific antibodies from anti-NKp46 OmnidAb and OmniClic clones (KD values reported beneath plots) using either the standard anti-hFC capture approach (FIG. 12C) or the EGFR- tethered (sandwich) approach (FIG.12D). Measured data are shown in blue-green with global fits overlaid in red. Data shows that simultaneous binding of EGFR and NKp46 does not affect NKp46 binding kinetics. FIGS.13A-13C. Shows binding kinetics of select EGFR-NKp46 bispecific antibodies. A schematic of a standard anti-human Fc capture approach is shown (FIG.13A). Global fits showing diverse kinetic profiles for select bispecific antibodies from two anti-NKp46 OmnidAb clones and one OmniClic clone (FIG.13A and FIG.13B). Measured data are shown in blue-green with global fits overlaid in red. Data show EGFR binding kinetics are unaffected by reformatting into a NKp46 bispecific construct, with either an active or silenced Fc. FIG.14. Shows capture kinetics of select NKp46 stalk-knob (SK) IgG antibodies. Schematics of a NKp46 knob containing monospecific and bispecific format are shown. Global fits showing kinetic profiles for a select monospecific and bispecific format showed high affinity binding for either format. Measured data are shown in blue-green with global fits overlaid in red. Data demonstrate knobs can be used as versatile building blocks to construct custom molecular formats. Atty. Dkt: OMNI-002WO DETAILED DESCRIPTION Before the present invention is further described, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. It must be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a binding domain” includes a plurality of binding domains. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed. In the following description, the CDRs are defined by the IMGT system of Lefranc (Dev. Comp. Immun.200327: 55–77). Atty. Dkt: OMNI-002WO VHH domain polypeptides VHH antibodies are known in the art and have a heavy chain variable domain that can fold and bind to epitopes autonomously, i.e., without an associated light chain and without significantly aggregating. These antibodies may be referred to as “heavy chain-only”, “HCO” or single domain antibodies (sdAbs), shark antibodies, camelid antibodies and nanobodies in other publications. VHH antibodies occur naturally in shark, camel and llama. However, there are several strategies for producing such antibodies from VH antibodies. See, e.g., Janssens et al (Proc. Natl. Acad. Sci.2006103:15130-5), Brüggemann et al (Crit. Rev. Immunol.200626:377-90), Zou et al (J. Immunol.2005175:3769-79) and Nguyen et al (Immunology 2003109: 93-101), for example. A VHH variable domain can be made by introducing substitutions into the variable domain of a VH antibody. Such stabilized or ‘camelized’ VH antibodies are referred to as VHH antibodies herein and, as may be apparent, the term “VHH” could be substituted with the term “heavy chain-only”, “HCO”, “autonomous heavy chain” or “single domain” since these terms are intended to refer to the same thing. In the present disclosure, VHH antibodies were made by chickens that have been genetically engineered to produce VHH antibodies. Advantageous features of VHH antibodies include their small size, high solubility, high stability, and excellent tissue penetration in vivo. VHH antibodies can readily be linked genetically to, e.g., Fc-domains, other nanobodies or single chain antibodies, peptide tags, or toxins and can be conjugated chemically at a specific site to drugs, radionuclides, photosensitizers, and nanoparticles, etc. The binding domain of a VHH antibody does not require a light chain for correct folding or binding to an antigen. See, e.g., Bever et al (Anal Bioanal Chem.2016 Sep; 408: 5985–6002). As with conventional VH antibodies, VHH antibodies have three CDRs (CDR1, CDR2 and CDR3) that are flanked by framework. The structure of the binding domain (which may be referred to as a ‘variable domain’) of a VHH antibody is as follows: FW1-CDR1- FW2-CDR2-FW3-CDR3-FW4 (see, e.g., Noel et al, Biochimie 2016131:11-19 for a detailed description of VHH structure). Using Tables 1, 2, 10 and 11 as a reference, the present disclosure provides a polypeptide that comprises a VHH domain comprising: (a) CDR1, CDR2 and CDR3 regions that are identical to the CDR1, CDR2 and CDR3 regions of a VHH antibody selected from Tables 1 and 10 or (b) CDR1, CDR2 and CDR3 regions that are otherwise identical to the CDR1, CDR2 and CDR3 regions of a VHH antibody selected from Tables 1 and 10 except for up to 10 (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1) amino acid substitutions in the collective CDR regions, wherein the VHH domain binds to NKp46. In some embodiments, the amino acid sequence of the VHH domain may be at least 90% (e.g., at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% Atty. Dkt: OMNI-002WO or at least 99%) identical to the variable domain of the selected VHH antibody. These sequences are shown in Tables 2 and 11. In any embodiment, the polypeptide that comprises a VHH domain may comprise at least the FR2 (i.e., the sequence between CDR1 and CDR2) of the selected VHH antibody, or a FR2 that is otherwise identical to the FR2 of the selected VHH antibody except for up to 10 (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1) amino acid substitutions in the FR2 In some embodiments, the VHH may be humanized, i.e., modified so that it becomes more like a human antibody and therefore less immunogenic, methods for which are known. Common light chain antibodies Common light chain antibodies are antibodies that are composed of a heavy and light chain that are made in an animal that has a ‘fixed’ light chain, i.e., a light chain that has a diminished capacity to diversify. The antibodies produced by such an animal have a diversified heavy chain and the same light chain (i.e., a ‘common’ light chain). In these animals the heavy chain sequence is diversified and capable of high-affinity antigen-specific binding and broad epitope diversity when paired with a light chain (which, in many cases, will be a human light chain). The light chain provides the proper structure for assembly of the full antibody molecule but is a passive partner for antigen binding. Transgenic animals that produce common light chain antibodies include rats (see, e.g., Harris et al (Front Immunol.2018 24:9:889)) and chickens (Ching et al (MAbs.2021; 13(1): 1862451)), among others. Common light chain antibodies find particular use in producing multispecific antibodies, since it is advantageous if the light chain is common to all branches of the multispecific antibody, with the binding specificity determined solely by the heavy chain. For example, expression of a bispecific antibody is simplified because it only requires the two heavy chains and the one, common light chain. Common light chain antibodies have a conventional “VH” structure and have both a heavy chain sequence and a light chain sequence. Both the heavy and light chains of a common light chain antibody have the following structure: FW1-CDR1-FW2-CDR2-FW3-CDR3-FW4. Using Tables 3 and 4 (which describe common light chain rat antibodies) as well as Tables 6 and 7 (which describe common light chain chicken antibodies) as a reference, the present disclosure provides a polypeptide comprising an antibody binding domain that comprises a heavy chain variable domain and a light chain variable domain (which may be in a single chain or two chains (e.g., in the scFv or Fab formats)), where the binding domain comprises: (i) a heavy chain variable domain comprising CDR1, CDR2 and CDR3 regions that are identical to the heavy chain CDR1, CDR2 and CDR3 regions of a common light chain antibody selected from Table 3 or 6 or are otherwise identical to the heavy chain CDR1, CDR2 and CDR3 regions of a common light chain antibody selected from Table 3 or 6 except for Atty. Dkt: OMNI-002WO up to 10 (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1) amino acid substitutions in the collective CDR regions; and (ii) a light chain variable domain comprising CDR1, CDR2 and CDR3 regions that are identical to the light chain CDR1, CDR2 and CDR3 regions of the selected common light chain antibody or are otherwise identical to the light chain CDR1, CDR2 and CDR3 regions of the selected common light chain antibody except for up to 10 (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1) amino acid substitutions in the collective CDR regions, wherein the antibody binding domain binds to NKp46. In some embodiments, the antibody binding domain may comprise: (a) (i) a heavy chain variable domain comprising CDR1, CDR2 and CDR3 regions that are identical to the heavy chain CDR1, CDR2 and CDR3 regions of a common light chain antibody selected from Table 3 or 6; and (ii) a light chain variable domain comprising CDR1, CDR2 and CDR3 regions that are identical to the light chain CDR1, CDR2 and CDR3 regions of the selected common light chain antibody; or (b) (i) a heavy chain variable domain comprising CDR1, CDR2 and CDR3 regions that are otherwise identical to the heavy chain CDR1, CDR2 and CDR3 regions of a common light chain antibody selected from Table 3 or 6 except for up to 10 (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1) amino acid substitutions in the collective CDR regions; and (ii) a light chain variable domain comprising CDR1, CDR2 and CDR3 regions that are otherwise identical to the light chain CDR1, CDR2 and CDR3 regions of the selected common light chain antibody except for up to 10 (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1) amino acid substitutions in the collective CDR regions, where the antibody binding domain binds to NKp46. In some embodiments, the antibody binding domain may have one chain that has CDRs that are identical to the CDRs of an antibody from tables 3 and 6, where the CDRs of other chain are otherwise identical to the other chain of the selected antibody except for up to 10 (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1) amino acid substitutions in the collective CDRs. In these embodiments, the binding domain may comprise: (a) (i) a heavy chain variable domain comprising CDR1, CDR2 and CDR3 regions that are identical to the heavy chain CDR1, CDR2 and CDR3 regions of a common light chain antibody selected from Table 3 or 6; and (ii) a light chain variable domain comprising CDR1, CDR2 and CDR3 regions that are otherwise identical to the light chain CDR1, CDR2 and CDR3 regions of the selected common light chain antibody except for up to 10 (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1) amino acid substitutions in the collective CDR regions or (b) (i) a heavy chain variable domain comprising CDR1, CDR2 and CDR3 regions that are otherwise identical to the heavy chain CDR1, CDR2 and CDR3 regions of a common light chain antibody selected from Table 3 or 6 except for up to 10 (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1) amino acid substitutions in the collective CDR regions; and (ii) a light chain variable domain comprising CDR1, CDR2 and CDR3 regions that are identical to the light chain CDR1, CDR2 and CDR3 regions of the selected common light chain antibody; where the antibody binding domain binds to NKp46 Atty. Dkt: OMNI-002WO In some embodiments, the antibody binding domain comprises a heavy chain variable domain that is at least 90% (e.g., 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 heavy chain variable domain of the selected antibody and a light chain variable domain that is at least 90% (e.g., 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 light chain variable domain of the selected antibody. These sequences are shown in Tables 4 and 7. In some embodiments, the antibody binding domain may be humanized, i.e., modified so that it becomes more like a human antibody and, in theory, less immunogenic, methods for which are known. Knob domains Cattle (i.e., cows or bovines) produce antibodies that have a cysteine-rich ultralong CDR H3 that can be in the range of 30 to 70 amino acids in length and folds into a unique “stalk and knob” domain, with the knob protruding far out of the antibody surface (see, e.g., Huang et al Proc. Natl. Acad. Sci. 2023120: e2303455120). These knobs retain their ability to bind to the antigen when they are expressed on their own, i.e., independently from the rest of the antibody. In these embodiments, the knob can be expressed as a fusion protein which is then cleaved to release the knob (see, e.g., Huang et al Proc. Natl. Acad. Sci.2023120: e2303455120). Alternatively, the knob can be cleaved from an antibody or Fab scaffold (Macpherson et al. PLoS Biol 202018: e3000821) or synthesized chemically (Macpherson et al ACS Chem. Biol.202116, 9, 1757–1769). These knobs (which are referred to as “knob domains” herein and may be referred to as PICOBODIESTMelsewhere) are the smallest known fragment of an antibody that can bind to an antigen independently. A knob domain may be expressed on its own or as a fusion with another protein (referred to as a “fusion partner” herein), wherein the knob domain may be at the N- terminus, C-terminus or within the fusion partner. If the fusion partner is an antibody, the knob domain may be fused to the N- or C- terminus of the heavy or light chain (in which case the antibody could potentially be bispecific since the variable domain may be intact), or it could positioned in the variable domain of the antibody (e.g., in the heavy chain CDR3). In embodiments in which the knob domain is fused to another protein, the knob domain may in some cases additionally comprise a stalk and / or a flexible linker that connects the knob domain to the protein. For example, if the knob domain is in the heavy chain CDR3, then it may contain a stalk to allow it to protrude from the rest of the antibody. If the knob domain is expressed in conjunction with a stalk, then an almost unlimited number of sequences are available for the ascending and descending regions of the stalk. Specifically, in the context of bovine antibodies the stalk has a purely structural function (i.e., it does not participate in binding). In bovine antibodies, the stalk is a beta sheet (composed of two anti-parallel beta strands that are hydrogen bonded). Stalk sequences should be interchangeable between antibodies because, functionally, they only Atty. Dkt: OMNI-002WO serve to distance the knob from the rest of the antibody while keeping the ends of the knob in proximity with one another. Since the sequences of thousands of bovine antibodies are publicly available or could be readily obtained, a large number of options would be available. Moreover, methods for designing beta sheets (composed of two anti-parallel beta strands) de novo are well known (see, e.g., Hecht et al (Proc Natl Acad Sci U S A.199491: 8729–8730), Marcos (Nat Struct Mol Biol .201825: 1028-1034) and Pan et al (J. Biol. Chem.2021296, 100558), among many others)) and, as such, stalks can be readily designed. As such, a knob domain is typically in the range of 15 to 50 amino acids in length, cysteine-rich (i.e., may contain 4-10 cysteines, e.g., 4, 6, 8 or 10 cysteines) and may be based on an ultralong-CDR3 antibody (which, e.g., may be made by a cow or another species that naturally makes such antibodies, or by another species that has been engineered to produce such antibodies (e.g., a chicken)). Knob domains have the potential to bind antigens with concave epitopes and, as such, may have particular value for certain targets. Further details of knob domains may be found in, e.g., Svilenov et al (Nature Com.2021 12: 6737), Huang et al (Proc. Natl. Acad. Sci 2023120 (39) e2303455120) and Passon et al (Biotechnol Adv.2023 :64:108120). Table 9 of the present disclosure provides the sequences of a number of ultralong CDR H3s from cow antibodies that bind to NKp46. These sequences have stalk sequences at the ends and an internal knob domain. The knob domains of the ultralong CDR H3s are underlined in the sequences of Table 9. In some embodiments, the polypeptide may comprises a knob domain underlined in this table, where the knob domain may comprise an amino acid sequence that is the same as or comprises up to 10 (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1) amino acid substitutions relative to the knob domain of an ultralong CDR3 domain selected from Table 9. In some embodiments, the knob domain may be associated with stalk sequences (e.g., the sequences that are already associated with that domain in Table 9 or another pair of sequences that form an anti-parallel beta strand). In some embodiments, a knob domain may comprise an amino acid sequence that is at least 90% (e.g., 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 sequence of a knob domain or ultralong CDR3 selected from Table 9. In some embodiments, the knob domain may be grafted into the heavy chain CDR3 region of an antibody along with stalk sequences, i.e., to replace the heavy chain CDR3 region of an antibody. In these embodiments, the antibody may be a human antibody, a humanized antibody, or a variant of the same that has been modified to accommodate an ultralong heavy chain CDR. As such, in some embodiments, some embodiments provide an antibody that has a heavy chain CDR3 that comprises a knob domain, wherein the knob domain has been grafted onto the antibody. Atty. Dkt: OMNI-002WO Multispecific Antibodies In some embodiments, the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or knob domain, as described above, and at least one other binding domain. These domains are connected by a suitable linker, many of which are known in the art. The at least one other binding domain may be another VHH domain, a scFv, a ligand for a cell surface receptor, or it may be based on an alternative scaffold. In these embodiments, at least one of the other binding domains may recognize a cancer antigen (i.e., an antigen found on the surface of cancer cells). Such antigens include e.g., CD19, CD20, BCMA, ALPP, CS1 (SLAMF7), CLDN18.2, AXL, ROR2, TM4SF1, ICAM-1, L1CAM (CD171), CD4, CD5, CD7, CD10, CD38, CEA, FLT3, CD70, CD30, CD37, or CD147, although there are many others. The cancer antigen may be a blood cell antigen or a solid tumor antigen, depending on how the polypeptide is going to be used. In alternative embodiments, at least one of the other binding domains may recognize a viral antigen on a cell that is infected by a virus. In these embodiments, the polypeptide may be an NK cell engager (i.e., an NKCE, alternatively known as a killer cell engager) where, in some embodiments, the polypeptide may be a bispecific NK cell engager (referred to as a “BiKE” in some publications) or a trispecific K cell engager (referred to as a “TriKE” in some publications. BiKEs and TriKEs are reviewed in Felices et al (Methods Mol Biol. 2016; 1441: 333–346). Such molecules tether NK cells to a tumor cell and induce their activation at that site. BiKEs and TriKEs are molecules that contain a single variable portion of an antibody linked to one (BiKE) or two (TriKE) variable portions from other antibodies of different specificity. As such, in some embodiments, the polypeptide may be a bispecific binding molecule that comprises (i) the VHH domain, the antibody binding domain or the knob domain and (ii) a binding domain that recognizes a first antigen found on the surface of cancer cells. In other embodiments, the polypeptide may be a bispecific binding molecule that comprises (i) the VHH domain, the antibody binding domain or the knob domain, (ii) a binding domain that recognizes a first antigen on the surface of cancer cells and (iii) either a binding domain that recognizes a co-stimulatory receptor or a binding domain that recognizes a second antigen on the surface of cancer cells. In these latter embodiments, it has been noted that NKp46 synergizes with other immune receptors (referred as co-stimulatory receptors or co-receptors herein), e.g., 2B4, DNAM1 and CD2 (see, e.g., Zmai et al Cells 20209: 753) and, as such, a bispecific binding molecule may bind to NKp46 and one or more of 2B4, DNAM1, or CD2. NKp46 provides a better alternative to CD16 (another NK cell-specific stimulatory immune receptor) in some embodiments, because CD16 levels are downregulated by NK cells in the tumor microenvironment. Atty. Dkt: OMNI-002WO Multispecific antibodies can be in a variety of different formats, including, but not limited to IgG-like antibody formats (including an Fc domain) and non-IgG-like antibody formats (without an Fc domain). Multispecific antibodies with IgG-like antibody formats can be in a variety of different formats, including, but not limited to knob-into-hole (KIH), TrioMab, Duobody, κλ body, CrossMab, common light chain, strand exchange engineered domain bodies (SEEDBodies), Azymetric heterodimeric Fc, dual action Fab (DAF), dual-variable-domain immunoglobulin (DVD-Ig), IgG-scFv, Fab-Fab-Fc, DutaMab, and DutaFab. Non-IgG-like antibody formats may lack an Fc region entirely. For example, Fab, Fv and VHH antibody regions may be genetically engineered and combined in various orientations and pairings. Multispecific antibodies in non-IgG-like formats can be in a variety of different formats, including, but not limited to bivalent dual-affinity re-targeting protein (DART), tetravalent DART, half-life extended bispecific T-cell engager (HLE-BiTE), bispecific T-cell engager (BiTE), immune mobilizing monoclonal T-cell receptor (ImmTAC), tandem diabody (TandAb), bispecific killer T-cell engager (BiKE), trispecific killer T-cell engager (TRiKE), multispecific scFV single-chain variable fragment, trispecific T-cell activation construct (TriTAC), bispecific nanobody, and cross-over dual variable region (CODV). Multispecific antibodies may be bifunctional, trifunctional or even tetrafunctional. Multispecific antibodies may be IgG-fusion proteins. These antibody formats have been reviewed in a variety of publications, including Elshiaty et al. (2021), International Journal of Molecular Science, 22(11):5632; Jin et al. (2022), Signal Transduction Targeted Therapy, 7(39); Weidle et al. (2013), Cancer Genomics & Proteomics 10:1-18). Modified Fc domains A polypeptide of the present disclosure may have a modified Fc domain (i.e., an Fc domain with enhanced or decreased functionality) (see, e.g., van der Horst et al Cancers (Basel) 202012: 3041 and Wilkinson et at (PLoS One.2021; 16: e0260954) or no Fc domain. In some embodiments, a polypeptide may have an Fc region that has been modified to abolish or reduce binding to the Fc receptor. Amino acid substitutions that abolish or reduce Fc binding to the Fc receptor include, but are not limited to: L234A / L235A (LALA), L234F / L235E / P331S (FES), L234F / L235Q / K322Q (FQQ), L234A / G237A, L234A / L235A / G237A, L234A / L235A / G237A / P238S / H268A / A330sS / P330S, L234A / L235E, G236R / L328R, L234S / L235T / G236R (STR) and L234A / L235A / K322A. See, e.g., Wilkinson et at (PLoS One.2021; 16: e0260954). Antibody-Drug Conjugates (ADCs) In any embodiment, the present polypeptide can be conjugated to a drug. In these embodiments, the polypeptide may be a component of an antibody drug conjugate. Antibody drug conjugates (ADCs) Atty. Dkt: OMNI-002WO are targeted medicines that deliver therapeutic agents to cells, e.g., cancer cells. ADCs deliver the agent via a linker attached polypeptide (typically an antibody) that binds to a specific target expressed on the cells. In some embodiments, after binding to its target, the ADC releases an agent into or on the cell. In some embodiments, the agent is not released and, rather, the polypeptide holds the drug close to the site at which it is believed to be effective (e.g., near to its binding site on a receptor). Antibody-drug conjugates are reviewed in several publications, including Peters (Biosci Rep.201535: e00225). ADC Payloads An ADC of the present disclosure comprises a pharmacologically active agent, e.g., an enzyme inhibitor, an ion channel inhibitor, a peptide, a nucleic acid, small molecule or a cytotoxic and / or cytostatic agent, which may be referred to as the “payload” of the ADC. The payload of an ADC of the present disclosure may be any pharmacologically active agent or drug suitable to achieve the intended physiological effect, e.g., modulating the expression of a gene, modulating the activity of an enzyme, modulating the activity of a signaling pathway, inhibiting cell division. In varying embodiments, the pharmacologically active agent may exert a physiological effect relevant for treating, by way of example, cancers, cardiovascular disorders, gastrointestinal disorders, genito-urological disorders, hematological disorders, hormonal disorders, infectious disease, metabolic disorders, muscular disorders, neurological disorders, ophthalmologic disorders, and respiratory disorders. The payload can be an anti-inflammatory agent, a ligand for a receptor (e.g., a growth factor or cytokine), or a nucleic acid (e.g., an oligonucleotide) that effects alters gene expression of the cell to which the polypeptide binds. In some embodiments, the payload of an ADC of the present disclosure may be a cytostatic and / or cytotoxic agent. Cytotoxic agents are drugs that result in cell death, whereas cytostatic agents are drugs that inhibit cellular proliferation. In practice many drugs act as cytotoxic and cytostatic agents depending on dosage or biological context. Accordingly, the designation “cytotoxic” and “cytostatic” are used interchangeably herein. Both cytotoxic and cytostatic agents may be chemotherapeutic and may shrink and / or limit growth of a tumor. Cytotoxic and / or cytostatic agents that are suitable for use as payloads in ADCs have been generally reviewed in several publications, including: Theocharopoulos et al.2021 (Theocharopoulos, Charalampos, et al. "Antibody-drug conjugates: Functional principles and applications in oncology and beyond." Vaccines 9.10 (2021): 1111) and Anand et al.2023 (Anand, Uttpal, et al. "Cancer chemotherapy and beyond: Current status, drug candidates, associated risks and progress in targeted therapeutics." Genes & Diseases 10.4 (2023): 1367-1401), the entirety of each being incorporated herein by reference. Microtubule Inhibitors Atty. Dkt: OMNI-002WO In some embodiments, the cytotoxic payload of an ADC of the present disclosure may be a microtubule inhibitor or microtubule disrupting agent. Microtubule assembly plays a critical role in cell division and cellular transport, among other key cellular functions, and inhibition of microtubule assembly leads to arrest of cell division and / or cell death. In some cases, the microtubule inhibitor may be an auristatin or analogues and derivatives thereof. Auristatins are synthetic analogues of the natural molecule Dolostatin 10, isolated from Dolabella Auricularia. Suitable auristatins and auristatin derivatives for use as a payload include, without limitation, monomethyl auristatin E (MMAE; CAS Registry No.474645-27-7), monomethyl auristatin F (MMAF; CAS Registry No.745017-94-1), and monomethyl auristatin D (MMAD; CAS Registry No.203849-91-6). The auristatin MMAE, for example, has been used as the cytotoxic payload in the clinically approved ADCs brentuximab vedotin, inotuzumab ozogamicin, gemtuzumab ozogamicin, polatuzumab vedotin. In some cases, the microtubule inhibitor may be a maytansinoid or derivatives thereof. Maytansinoids are derived from the natural molecule maytansine, isolated from Maytenus ovatus. Suitable maytansinoids and maytansinoid derivatives for use as a payload include, without limitation, maytansine (CAS Registry No.35846-53-8) and mertansine (DM1; CAS Registry No.139504-50-0). The maytansinoid DM1, for example, has been used as the cytotoxic payload in the clinically approved ADC trastuzumab emtansine. Other suitable microtubule inhibitors include, by way of example and without limitation, colchicine (CAS Registry No. 64868), halichondrin B (CAS Registry No.103614-76-2), rhizoxin (CAS Registry No.90996-54-6), paclitaxel (CAS Registry No.33069-62-4), and vinca alkaloids such as vindesine (CAS Registry No. 53643-48-4). Microtubule inhibitors / disrupting agents are known in the art and described, for example, in Wang et al.2023 (Wang, Xingyu, et al. "Microtubule‐targeting agents for cancer treatment: Seven binding sites and three strategies." MedComm–Oncology 2.3 (2023): e46), the entirety of which is incorporated herein by reference. DNA-damaging agents In some embodiments, the cytotoxic payload of an ADC of the present disclosure may be a DNA-damaging agent. DNA-damaging agents act through a variety of mechanisms and include, for example, alkylating agents, DNA intercalators, and topoisomerase inhibitors. In some cases, the DNA-damaging agent may be a calicheamicin or derivatives thereof. Calicheamicins are anticancer antiobiotics isolated from the actinomycete Micromonospora echinospora spp. Calichensis. Calicheamicins bind the minor groove of DNA in a site-specific manner and reductive cleavage by thiols present in a cell generates reactive diradical species that lead to strand scission of the DNA and, subsequently, cell death. Suitable calicheamicins and calicheamicin derivatives for use as a payload include, without limitation, calicheamicin γ1 (CAS Registry No.108212-75-5) and Atty. Dkt: OMNI-002WO N-acetyl-gamma calicheamicin 1,2-dimethyl hydrazine. Calicheamicins have, for example, been used as the cytotoxic payload in the clinically approved ADCs inotuzumab ozogamicin and gemtuzumab ozogamicin. Calicheamicin and derivatives thereof are known in the art and described, for example, in Maiese at al.1989 (Maiese, William M., et al. "Calicheamicins, a novel family of antitumor antibiotics: taxonomy, fermentation and biological properties." The Journal of antibiotics 42.4 (1989): 558-563), the entirety of which is incorporated herein by reference. In some cases, the DNA-damaging agent may be a pyrrolobenzodiazepine (PBD) or derivatives thereof. PBDs can alkylate and cross-link opposite DNA strands, preventing strand separation during genomic replication and inducing cell death. Suitable PBDs for use as a payload include, without limitation, tesirine (SG3249; CAS Registry No.1595275-62-9) and SJG-136 (CAS Registry No.232931- 57-6). The PBD tesirine, for example, has been used as the cytotoxic payload in the clinically approved ADC loncastuximab tesirine. PBDs and derivatives thereof are known in the art and are described, for example, in: Mantaj et al.2017 (Mantaj, Julia, et al. "From anthramycin to pyrrolobenzodiazepine (PBD)‐containing antibody–drug conjugates (ADCs)." Angewandte Chemie International Edition 56.2 (2017): 462-488), the entirety of which is incorporated herein by reference. In some cases, the DNA-damaging agent may be a topoisomerase inhibitor, e.g., a topoisomerase I or topoisomerase II inhibitor. Topoisomerases are necessary for regulating DNA topology and torsional stresses during DNA replication, repair and transcription. In certain embodiments, the topoisomerase inhibitor may be a topoisomerase I inhibitor, e.g., a camptothecin or a derivative thereof. Camptothecin and its derivates inhibit topoisomerase I, inhibiting replication and causing cleavage of the DNA. Suitable camptothecins and camptothecin derivatives for use as a payload include, without limitation, camptothecin (CAS Registry No.7689-03-4), topotecan (CAS Registry No.123948-87-8), irinotecan (CAS Registry No.97682-44-5), belotecan (CAS Registry No.256411-32-2), exatecan (CAS Registry No.171335-80-1), deruxtecan (CAS Registry No.1599440-13-7), and SN-38 (CAS Registry No.86639- 52-3). The camptothecin analog deruxtecan, for example, has been used as the payload in the clinically approved ADC trastuzumab deruxtecan. In certain embodiments, the topoisomerase inhibitor may be a topoisomerase II inhibitor, e.g., an anthracycline, anthracenedione, acridine, epipodophyllotoxin, or derivatives thereof. Anthracyclines intercalate DNA and poison DNA-topoisomerase II complexes, inhibiting DNA replication and causing cell death. Additionally, anthracyclines generate free-radicals in an iron-dependent manner, further enhancing their cytotoxic effects. Suitable anthracycline and anthracycline derivatives for use as a payload include, without limitation, doxorubicin (CAS Registry No.23214-92-8), epirubicin (CAS Registry No.56420-45-2), valrubicin (CAS Registry No.56124-62- 0), daunorubicin (CAS Registry No.20830-81-3), idarubicin (CAS Registry No.58957-92-9), and PNU- Atty. Dkt: OMNI-002WO 159682 (Cas Registry No.202350-68-3). Anthracenediones, acridines, epipodophyllotoxins, and derivatives thereof intercalate DNA and poison DNA-topoisomerase II complexes, inhibiting DNA replication and causing cell death. Suitable anthracenediones and anthracenedione derivatives for use as a payload include, without limitation, mitoxantrone (CAS Registry No.65271-80-9) and pixantrone (CAS Registry No.144510-96-3). Suitable epipodophyllotoxins and epipodophyllotoxin derivatives include, without limitation, etoposide (CAS Registry No.33419-42-0) and teniposide (CAS Registry No. 29767-20-2). Various classes of topoisomerase inhibitors are known in the art and described, for example, in Yakkala et al.2023 (Yakkala PA, Penumallu NR, Shafi S, Kamal A. “Prospects of Topoisomerase Inhibitors as Promising Anti-Cancer Agents”. Pharmaceuticals (Basel).2023 Oct 13;16(10):1456), the entirety of which is incorporated herein by reference. In some cases, the DNA-damaging agent may be an alkylating agent. Alkylating agents interact with DNA and form covalent adducts to cross-link DNA or cross-link DNA with protein, leading to DNA cleavage, inhibition of replication, and cell death. Suitable alkylating agents for use as a payload include, without limitation, adozelesin (CAS Registry No.110314-48-2) carboplatin (CAS Registry No. 41575-94-4), chlorambucil (CAS Registry No.305-03-3), cisplatin (CAS Registry No.15663-27-1), cyclophosphamide (CAS Registry No.50-18-0), lomustine (CAS Registry No.13010-47-4), melphalan (CAS Registry No.148-82-3), mitomycin C (CAS Registry No.50-07-7) and temozolomide (CAS Registry No.85622-93-1). Other Cytotoxic / Cytostatic Agents In some embodiments, the cytotoxic payload of an ADC of the present disclosure may be an antimetabolite, a protein-synthesis inhibitor, a mitochondrial inhibitor, a histone deacetylase (HDAC) inhibitor, or a cell-cycle disruptor. Antimetabolites inhibit metabolic pathways, e.g., nucleic acid or amino acid synthesis, necessary for cell proliferation and survival. Exemplary antimetabolites include 5- fluorouracil (5-FU; CAS Registry No.51-21-8) and fludarabine (CAS Registry No.21679-14-1), among others. Various classes of antimetabolites are known in the art and described, for example, in: Cole et al. 2005 (Cole, Peter D., John A. Zebala, and Barton A. Kamen. "Antimetabolites: A new perspective." Drug Discovery Today: Therapeutic Strategies 2.4 (2005): 337-342), the entirety of which is incorporated herein by reference. Protein-synthesis inhibitors disrupt translation of mRNAs through different mechanisms. Exemplary protein-synthesis inhibitors include tomivosertib (eFT-508; CAS Registry No.1849590-01-7), zotatifin (CAS Registry No.2098191-53-6), and silvestrol (CAS Registry No.697235-38-4). Various classes of protein-synthesis inhibitors are known in the art and described, for example, in Kovalski et al.2022 (Kovalski, Joanna R., Duygu Kuzuoglu‐Ozturk, and Davide Ruggero. "Protein synthesis control in cancer: selectivity and therapeutic targeting." The EMBO Journal 41.8 Atty. Dkt: OMNI-002WO (2022): e109823), the entirety of which is incorporated herein by reference. Mitochondrial inhibitors disrupt mitochondrial function and or cellular respiration. Exemplary mitochondrial inhibitors include tamoxifen (CAS Registry No.10540-29-1), gamitrinib (CAS Registry No.1131626-46-4), and tigecycline (CAS Registry No.220620-09-7). HDAC inhibitors disrupt the regulation of gene-expression by HDAC mediated remodeling of chromatin. Exemplary HDAC inhibitors include trichostatin A (CAS Registry No.58880-19-6), and SK-7041 (CAS Registry No.617690-98-9). Various classes of HDAC inhibitors are known in the art and described, for example, in Shanmugam et al.2022 (Shanmugam, Geetha, Sudeshna Rakshit, and Koustav Sarkar. "HDAC inhibitors: Targets for tumor therapy, immune modulation and lung diseases." Translational Oncology 16 (2022): 101312), the entirety of which is incorporated herein by reference. Cell-cycle disruptors interfere with the regulation of cell division, e.g., interfering with cyclin-CDK function. Exemplary cell-cycle disruptors include flavopiridol (CAS Registry No.146426-40-6), dinacicilib (CAS Registry No.779353-01-4), and roniciclib (CAS Registry No.1223498-69-8). Various classes of cell-cycle disruptors are known in the art and described, for example, in: Zhang et al.2021 (Zhang, Mengna, et al. "CDK inhibitors in cancer therapy, an overview of recent development." American journal of cancer research 11.5 (2021): 1913) and Bai et al.2017 (Bai, Jingwen, Yaochen Li, and Guojun Zhang. "Cell cycle regulation and anticancer drug discovery." Cancer biology & medicine 14.4 (2017): 348), the entirety of each being incorporated herein by reference. Nucleic Acid Payloads In some embodiments, the payload of an ADC of the present disclosure may be a nucleic acid, e.g., an RNA or DNA oligonucleotide. A key feature of nucleic acid payloads is the capability to offer highly selective modulation of, in theory, any gene of interest by designing to the nucleic acid payload to bind to a target nucleic acid through relatively simple Watson-Crick base pairing mechanisms. Nucleic acid payloads can be used to, for example, modulate the expression of a target gene through a variety of mechanisms that involve base-pairing to the target, e.g., base-pairing to a complementary sequence of a transcript of the target gene. Pharmacologically active nucleic acids, and uses thereof in ADCs, are known in the art and described, for example, in Dugal-Tessier et al.2021 (Dugal-Tessier, Julien, Srinath Thirumalairajan, and Nareshkumar Jain. "Antibody-oligonucleotide conjugates: a twist to antibody-drug conjugates." Journal of Clinical Medicine 10.4 (2021): 838) and Moumné et al.2022 (Moumné, Lara, Anne-Céline Marie, and Nicolas Crouvezier. "Oligonucleotide therapeutics: from discovery and development to patentability." Pharmaceutics 14.2 (2022): 260), of which the entirety of each is incorporated herein by reference. Anti-sense oligonucleotides (ASOs) Atty. Dkt: OMNI-002WO In some embodiments, the nucleic acid payload of an ADC of the present disclosure may be an anti-sense oligonucleotide (ASO). ASOs are designed to be complementary (i.e., anti-sense) to a target nucleic acid RNA transcript (e.g., an mRNA). In some cases, an ASO can modulate expression of a desired gene (e.g., a disease associated gene) by triggering degradation of the target gene transcript. For example, an DNA, or DNA-like, ASO can be designed to be complementary to a target RNA transcript and hybridize to form a DNA / RNA complex with the transcript. The ASO / transcript complex is then susceptible to the activity of RNAse H, which selectively degrades the RNA strands of DNA / RNA complexes, thereby degrading the hybridized target transcript. In some cases, the ASO can be designed to alter the expression of a specific isoform of a gene through modulation of RNA splicing. For example, an ASO can be designed to bind the intron-exon junction of the pre-mRNA of a target gene and sterically interfere with the spliceosome machinery and thereby alter splicing events. Suitable ASOs for use as a payload in an ADC of the present disclosure can include an ASO specific to, in principle, any conceivable gene of interest. In some embodiments, the ASO may be a known or clinically approved ASO specific to a known target. Exemplary known target gene-expression inhibiting ASOs suitable for use as a nucleic acid payload include, without limitation, TTR-targeting inotersen, TTR-targeting eplontersen, APOB targeting mipomersen, APOC3 targeting volanesorsen, APOC3-targeting olezarsen, CMV IE2-targeting fomivirsen, IRS1-targeting aganirsen, ICAM1-targeting alicaforsen, LPA-targeting, pelacarsen, SOD1-targeting tofersen, HTT-targeting tominersen, TGFB2- targeting trabedersen, GFAP-targeting zilganersen, GHR-targeting atesidorsen, GHR-targeting cimderlirsen, PCSK9-targeting cepadacursen, HBV-targeting bepirovirsen, STAT3-targeting danvatirsen, KLKB1-targeting donidalorsen, GRB2-targeting prexigebersen, and ANGPTL3-targeting vupanorsen. Exemplary known splice-modulating ASOs suitable for use as a nucleic acid payload include, without limitation, CEP290-targeting sepofarsen, DMD-targeting eteplirsen, DMD-targeting viltolarsen, DMD-targeting casimersen, DMD-targeting golodirsen, DMD-targeting renadirsen, and SMN2-targeting nusinersen. Short-interfering RNAs (siRNAs) In some embodiments, the nucleic acid payload of an ADC of the present disclosure may be a short-interfering RNA (siRNA). An siRNA is a double-stranded RNA molecule, a strand of which can hybridize to a complementary target RNA, that can induce degradation of the target RNA through recruitment of and incorporation into an RNA-induced silencing complex (RISC) in a target cell. Suitable siRNAs for use as a payload in an ADC of the present disclosure can include an siRNA specific to, in principle, any conceivable gene of interest. In some embodiments, the siRNA may be a known or Atty. Dkt: OMNI-002WO clinically approved siRNA. Exemplary known siRNAs suitable for use as a nucleic acid payload include, without limitation, TTR-targeting patisiran, TTR-targeting vutrisiran, ALAS1-targeting givosiran, PCSK9-targeting inclisiran, HAO1-targeting lumasiran, SERPINC1-targeting fitusiran, LDHA-targeting nedosiran, TP53-targeting teprasiran, TRPV1-targeting tivanisiran, ADRB2-targeting bamosiran, SERPINA1-targeting belcesiran, SERPINA1-targeting fazisiran, C5-targeting cemdisiran, LPA-targeting olpasiran, and AGT-targeting zilebesiran. Nucleic Acid Modifications In some embodiments, the nucleic acid payload of an ADC of the present disclosure comprises one or more modifications (e.g., a nucleobase modification, a sugar modification, a backbone modification) to improve, for example, affinity or the stability of the nucleic acid payload in circulating plasma. Suitable nucleic acid modifications include, by way of example, locked nucleic acid (LNA) modified nucleotides, peptide nucleic acid (PNA) modified nucleotides, 2’-O-Methyl modified nucleotides, 2’ fluoro modified nuclotides, and phosphorothioate linkages, among others. Nucleic acid modifications useful for nucleic acids (e.g., RNA or DNA oligonucleotides) with therapeutic applications are known in the art and described, for example, in WO 2007 / 047913, Ochoa et al.2020 (Ochoa, Steven, and Valeria T. Milam. "Modified nucleic acids: Expanding the capabilities of functional oligonucleotides." Molecules 25.20 (2020): 4659), Kulkarni et al.2021 (Kulkarni, Jayesh A., et al. "The current landscape of nucleic acid therapeutics." Nature nanotechnology 16.6 (2021): 630-643) and Moumné et al.2022 (Moumné, Lara, Anne-Céline Marie, and Nicolas Crouvezier. "Oligonucleotide therapeutics: from discovery and development to patentability." Pharmaceutics 14.2 (2022): 260), of which the entirety of each is incorporated herein by reference. G-protein Coupled Receptor (GPCR) Modulators In some embodiments, the payload of an ADC of the present disclosure may be a modulator of a G-protein coupled receptor (GPCR). GPCRs encompass the largest protein family encoded in the human genome and are involved in diverse physiological processes and have been implicated in many diseases ranging from type 2 diabetes to schizophrenia. GPCRs transduce extracellular signals in the form of varying ligands which induce a conformational change in the GPCR upon binding, subsequently leading to activation of G proteins and other downstream intracellular molecular pathways. GPCRs can be grouped into four classes based on their amino acid sequences: class A (rhodopsin-type), class B (secretin / adhesion-type), class C (glutamate-type), and class F (frizzled-type) GPCR subfamilies. The class A type GPCRs can be further subdivided into aminergic, peptide, lipid, protein, nucleotide, and steroid receptor GPCRs. Detailed investigation of the structure and function of GPCR activation has led Atty. Dkt: OMNI-002WO to the development of numerous molecular modulators for hundreds of GPCRs across each class described above. Suitable aminergic GPCR modulators for use as a payload may include any known or clinically approved aminergic GPCR modulator. Exemplary aminergic GPCR modulators suitable as payloads include, by way of example: Acebutolol, Acetophenazine, Acetylcholine, Aclidinium, Acrivastine, Benperidol, Benzphetamine, Benztropine, Bepotastine, Betahistine, Cabergoline, Carbachol, Carbinoxamine, Cariprazine, Carteolol, Dapiprazole, Darifenacin, Desipramine, Desloratadine, Dexbrompheniramine, Eletriptan, Emedastine, Ephedrine, Epinastine, Epinephrine, Famotidine, Fenoldopam, Fenoterol, Fesoterodine, Fexofenadine, Gilteritinib, Glycopyrronium, Guanabenz, Guanfacine, Haloperidol, Hexocyclium, Histamine, Homatropine methylbromide, Hydroxyzine, Iloperidone, Indacaterol, Indoramin, Ipratropium, Isoetharine, Ketotifen, Labetalol, Lasmiditan, Levobunolol, Levocabastine, Levocetirizine, Meclizine, Mepenzolate, Mephentermine, Mesoridazine, Metaproterenol, Nadolol, Naphazoline, Naratriptan, Nebivolol, Nefazodone, Olanzapine, Olodaterol, Olopatadine, Orphenadrine, Oxprenolol, Paliperidone, Pemirolast, Penbutolol, Pergolide, Perphenazine, Quetiapine, Ranitidine, Remoxipride, Revefenacin, Risperidone, Ritodrine, Salbutamol, Salmeterol, Scopolamine, Silodosin, Solifenacin, Tamsulosin, Tegaserod, Terazosin, Terbutaline, Terfenadine, Umeclidinium, Vilanterol, Vilazodone, Vortioxetine, Xylometazoline, Ziprasidone, Zolmitriptan, and Zuclopenthixol. Suitable peptide GPCR modulators for use as a payload may include any known or clinically approved peptide GPCR modulator. Exemplary peptide GPCR modulators suitable as payloads include, by way of example: Angiotensin II, Azilsartan medoxomil, Candesartan cilexetil, Eprosartan, Forasartan, Irbesartan, Losartan, Olmesartan medoxomil, Telmisartan, Valsartan, Icatibant, Ramipril, Captopril, Enalaprilat, Zinc, Zinc chloride, Zinc acetate , Zinc sulfate, Pentagastrin, Ambrisentan, Bosentan, Macitentan, Sitaxentan, Acetylsalicylic acid, Nedocromil , Macimorelin , Abarelix, Buserelin, Cetrorelix, Danazol, Degarelix, Ganirelix acetate, Gonadorelin, Goserelin, Histrelin, Leuprolide, Nafarelin, Triptorelin, Elagolix , Afamelanotide, Cosyntropin, Bremelanotide, Erythromycin, Cysteamine, Levocabastine, Alfentanil, Alvimopan, Anileridine, Buprenorphine, Butorphanol, Cocaine, Codeine, Dezocine, Difenoxin, Dihydrocodeine, Diphenoxylate, Eluxadoline, Ethylmorphine, Fentanyl, Hydrocodone, Hydromorphone, Ketobemidone, Levallorphan, Levorphanol, Levomethadyl acetate, Loperamide, Meperidine, Methadone, Methadyl acetate, Methylnaltrexone, Morphine, Nalbuphine, Naldemedine, Nalmefene, Naloxegol, Naloxone, Naltrexone, Oxycodone, Oxymorphone, Pentazocine, Propoxyphene, Remifentanil, Sufentanil, Tapentadol, Tramadol, Suvorexant, Lemborexant, Vorapaxar, Thrombin, Serelaxin, Gallium 68 DOTATOC, Lutetium Lu 177 dotatate, Pasireotide, Lanreotide, Atty. Dkt: OMNI-002WO Octreotide, Vapreotide, Aprepitant, Netupitant, Rolapitant, Fosnetupitant and palonestron, Protirelin, Atosiban, Conivaptan, Desmopressin, Oxytocin, Terlipressin, Tolvaptan, and Vasopressin. Suitable lipid GPCR modulators for use as a payload may include any known or clinically approved lipid GPCR modulator. Exemplary lipid GPCR modulators suitable as payloads include, by way of example: Dronabinol, Marinol, Nabilone, Tetrahydrocannabinol, Cannabidiol, Icosapent, Montelukast, Nedocromil, Pranlukast, Zafirlukast, Asfotase alfa, Fingolimod, Siponimod, Ozanimod, Rupatadine, Alprostadil, Bupivacaine, Bimatoprost, Carboprost tromethamine, Dinoprost tromethamine, Dinoprostone, Epoprostenol, Iloprost, Latanoprostene bunod, Latanoprost, Misoprostol, Ridogrelum, Selexipag, Tafluprost, Travoprost, Treprostinil, Gemeprost, Nedocromil, Indomethacin, and Sulindac. Suitable nucleotide GPCR modulators for use as a payload may include any known or clinically approved nucleotide GPCR modulator. Exemplary nucleotide GPCR modulators suitable as payloads include, by way of example: Adenosine, Caffeine, Regadenoson, Theophylline, Pentoxifylline, Defibrotide, Istradefylline, Tramadol, Gabapentin, Aminophylline, Oxtriphylline, Mefloquine, Lamotrigine, Fostamatinib, Cangrelor, Clopidogrel, Prasugrel, Suramin, Ticagrelor, Ticlopidine, Treprostinil, Epoprostenol, and Promethazine. Suitable class B GPCR modulators for use as a payload may include any known or clinically approved class B GPCR modulator. Exemplary class B GPCR modulators suitable as payloads include, by way of example: Calcitonin, Ubrogepant, Rimegepant, Pramlintide acetate, Secretin, Sermorelin, Tesamorelin, Albiglutide, Dulaglutide, Exenatide, Liraglutide, Lixisenatide, Semaglutide, Teduglutide, Glucagon, Abaloparatide, and Teriparatide. Suitable class C GPCR modulators for use as a payload may include any known or clinically approved class C GPCR modulator. Exemplary class C GPCR modulators suitable as payloads include, by way of example: Acamprosate, Baclofen, Cinacalcet, Etelcalcetide, Gamma hydroxybutyric acid, Progabide, and Vigabatrin. Suitable class F GPCR modulators for use as a payload may include any known or clinically approved class F GPCR modulator. Exemplary class F GPCR modulators suitable as payloads include, by way of example: Itraconazole, Sonidegib, Vismodegib, Glasdegib, Halcinonide, and Fluocinonide. Hundreds of known and clinically approved GPCR modulators are known in the art and reviewed extensively in several publications, including Hauser et al.2017 (Hauser, Alexander S., et al. "Trends in GPCR drug discovery: new agents, targets and indications." Nature reviews Drug discovery 16.12 (2017): 829-842) and Yang et al.2021 (Yang, Dehua, et al. "G protein-coupled receptors: structure-and function-based drug discovery." Signal transduction and targeted therapy 6.1 (2021): 7), of which the entirety of each is incorporated herein by reference. Atty. Dkt: OMNI-002WO Ion channel Modulators In some embodiments, the payload of an ADC of the present disclosure may be a modulator (e.g., an activator or inhibitor) of an ion channel. Ion channels are pore-forming transmembrane proteins that allow the passage of ions across cell and organelle membranes. Ion channels play key roles in diverse physiological processes such as regulating ion homeostasis, muscle contraction, nervous system signaling, and T cell activation, among others. Ion channels may be grouped by the ion species that the channel is permeable to, e.g., calcium, sodium, potassium, and proton channels. The ion permeability of many ion channels is conditionally dependent on surrounding physiological signals or conditions (i.e., the ion channels are “gated”). Ion channels may be further, or alternatively, grouped and classified by their gating mechanisms, e.g., voltage-gated, ligand-gated, and mechanosensitive ion channels. In some cases, the payload of an ADC of the present disclosure may be a calcium channel modulator. Calcium channels play important roles in a variety of physiological processes including muscle contraction, hormone release, neurotransmitter release, and gene transcription. Suitable calcium channel modulators for use as a payload include any known or clinically approved calcium channel inhibitor. Exemplary calcium channel modulators suitable for use as a payload include, without limitation, isradipine, nimodipine, cilnidipine, gabapentin, pregabalin, lamotrigine, topiramate, zonisamide, ethosuximide, ziconotide, valproate, nifedipine, SNX-482, agatoxins (e.g., ω-agatoxin IVA), conotoxins (e.g., ω-conotoxin MVIIA), calciseptine, and calcicludine. Calcium channel modulators are known in the art and described, for example, in Zamponi 2016 (Zamponi, Gerald W. "Targeting voltage- gated calcium channels in neurological and psychiatric diseases." Nature reviews Drug discovery 15.1 (2016): 19-34) and Pringos et al.2011 (Pringos, Emilie, et al. "Peptide neurotoxins that affect voltage- gated calcium channels: a close-up on ω-agatoxins." Toxins 3.1 (2011): 17-42), of which the entirety of each is incorporated herein by reference. In some cases, the payload of an ADC of the present disclosure may be a potassium channel modulator. Potassium channels can repolarize or hyperpolarize the membrane of excitable cell following potential firing, and thus work in conjunction with calcium and sodium channels in diverse physiological processes. Suitable potassium channel modulators for use as a payload include any known or clinically approved potassium channel modulator. Exemplary potassium channel modulators suitable for use as a payload include, without limitation, amiodarone, dofetilide, sotalol, azimilide, bretylium, clofilium, tedisamil, sematilide, astemizole, imipramine, verapamil, anemone BDS toxins, and mallotoxin. Potassium channel modulators are known in the art and described, for example, in Wolff et al.2009 (Wolff, H., N. A. Castle, and L. A. Pardo. "Voltage-gated potassium channels as therapeutic drug targets." Nat Rev Drug Discov 8 (2009): 982-1001) and Hopkins et al.1996 (Hopkins, W. F., J. L. Atty. Dkt: OMNI-002WO Miller, and G. P. Miljanich. "Voltage-gated potassium channel inhibitors." Current Pharmaceutical Design 2.4 (1996): 389-396). In some cases, the payload of an ADC of the present disclosure may be a sodium channel inhibitor. Sodium channels and channels are critical for the propagation of action potentials in excitable cells and, like calcium channels, play key roles in diverse physiological processes such as nerve signaling, muscle contraction, melanogenesis, and immune cell maturation, among others. Suitable sodium channel modulators for use as a payload include any known or clinically approved sodium channel modulator. Exemplary sodium channel modulators suitable for use as a payload include, without limitation, ciguatoxins, saxitoxins, gonyautoxins, batrachotoxins, tetrodotoxins, veratridine, grayanotoxin, aconitine, µ-conotoxins, µO-conotoxins, δ-conotoxins, ι-conotoxins, ProTx-I, ProTx-II, ProTx-III, HwTx-IV, ATX-II, and scorpion peptide toxins (ScTxs). Sodium channel modulators are known in the art and have been described, for example, in Cardoso et al.2018 (Cardoso, Fernanda C., and Richard J. Lewis. "Sodium channels and pain: From toxins to therapies." British journal of pharmacology 175.12 (2018): 2138-2157), the entirety of which is incorporated herein by reference. ADC Linkers The ADCs of the present disclosure comprise a polypeptide, e.g., an antibody, that is covalently linked to the payload via a linker. Linkers link payloads to the antibody through a covalent bond to the antibody at a first location of the linker and a covalent bond to the payload at a second location of the linker. Depending on the choice of linker, payload and antibody attachment site, various conjugation chemistries can be used to covalently attach linkers to the payload and antibody. Linkers may be broadly grouped into cleavable and non-cleavable linkers. The stability of the linker during circulation is critical for the controlled and targeted release of the payload to target cells and prevent off-target activity. Non-cleavable linkers require proteolysis of the antibody for release of the payload (e.g., lysosomal proteolysis of the antibody following internalization). Cleavable linkers enable the payload to be released from the ADC without proteolytic cleavage of the antibody, the cleavage of the linker being triggered by specific chemical or enzymatic cues (e.g., a chemical or enzymatic cue characteristic of a tumor microenvironment) to release the payload at its intended site of action. Suitable linkers can vary in length, hydrophilicity / hydrophobicity, and flexibility or can be comprised of distinct segments that each vary in one or more of the aforementioned properties. The properties of the linker can be varied in accordance with the properties of the payload. A hydrophilic linker, for example, may be chosen to pair with a hydrophobic payload to improve solubility and reduce aggregation of ADCs. In addition, a linker may be monovalent (i.e., link a single payload molecule to a Atty. Dkt: OMNI-002WO single site on the antibody) or polyvalent / branched (i.e., link more than one payload molecule to a single site on the antibody). ADC linkers have been generally reviewed in several publications, including: Jain et al.2025 (Jain, Nareshkumar, et al. "Current ADC linker chemistry." Pharmaceutical research 32.11 (2015): 3526- 3540), Maecker et al.2023 (Maecker, Heather, et al. "Exploration of the antibody–drug conjugate clinical landscape." MAbs. Vol.15. No.1. Taylor & Francis, 2023), Sasso et al.2023 (Sasso, Janet M., et al. "The Evolving Landscape of Antibody–Drug Conjugates: In Depth Analysis of Recent Research Progress." Bioconjugate Chemistry 34.11 (2023): 1951-2000), Sheyi et al.2022 (Sheyi, Rotimi, Beatriz G. de la Torre, and Fernando Albericio. "Linkers: An assurance for controlled delivery of antibody-drug conjugate." Pharmaceutics 14.2 (2022): 396), and Theocharopoulos et al.2021 (Theocharopoulos, Charalampos, et al. "Antibody-drug conjugates: Functional principles and applications in oncology and beyond." Vaccines 9.10 (2021): 1111), the entirety of each being incorporated herein by reference. Native and non-specific Attachment Sites In some embodiments the payload may be chemically conjugated to a native amino acid residue of the antibody (i.e., an amino acid residue that was not engineered into the antibody for the attachment of a linker) via a linker moiety. In some embodiments, the use of native amino acid residues as attachment sites requires no additional modification of the amino acid sequence of the antibody to enable attachment of the linker. In some cases, the conjugation of the linker and payload to native residues of the antibody is heterogeneous. In other words, the site of attachment and the total number of conjugated linkers with payloads can vary across ADCs in a given batch. In certain embodiments, the native amino acid residue is lysine, where the linker is covalently attached via the primary amine of the lysine residue. In such cases, the linker and payload may be reacted with the lysine via amide coupling using an activated carboxylic ester in the linker. For example, the primary amine of the lysine can be reacted with N-hydroxysuccinimide (NHS) esters introduced into the linker, forming a stable amide bond. Exemplary linker types that may be conjugated to a lysine residue include, without limitation, N-succinimidyl-4-(2-pyridyldithio)butanoate (SPDB) linkers, sulfo-SPDB linkers, maleimidomethyl cyclohexane-1-carboxylate (MCC), 4-(4-acetylphenoxy)butanoic acid (AcBut) linkers, and derivatives thereof. In certain embodiments, the native amino acid residue is cysteine, where the linker is covalently attached via the thiol group of the cysteine residue. In such cases, under controlled conditions, the antibody may be interchain disulfide bonds can be selectively reduced to generate reactive thiol groups in surface cysteine residues, while intrachain disulfides remain intact. The free thiol groups may then serve as reactive attachment sites to conjugate the linker via a variety of chemical reactions. For Atty. Dkt: OMNI-002WO example, the linker may be reacted with the free thiol group by Michael addition, a-halo carbonyl alkylation, or disulfide formation. Exemplary linker types that may be conjugated to a cysteine residue include, without limitation, maleimidocaproyl (MC) linkers, maleimidomethyl cyclohexane-1-carboxylate (MCC) linkers, and derivatives thereof. Available conjugation chemistries for attaching linkers to lysine and cysteine residues of an antibody are known in the art and reviewed, for example, in Lu et al.2016 (Lu, Jun, et al. "Linkers having a crucial role in antibody–drug conjugates." International journal of molecular sciences 17.4 (2016): 561), McDonagh et al.2006 (McDonagh, Charlotte F., et al. "Engineered antibody–drug conjugates with defined sites and stoichiometries of drug attachment." Protein Engineering, Design and Selection 19.7 (2006): 299-307), and Sun et al.2005 (Sun, Michael MC, et al. "Reduction− alkylation strategies for the modification of specific monoclonal antibody disulfides." Bioconjugate chemistry 16.5 (2005): 1282-1290). In addition, methods for conjugating linkers to cysteine residues of an antibody are described, for example, in WO 2014 / 197612. Engineered and Site-Specific Attachment Sites In some embodiments the payload may be conjugated via a linker to an engineered amino acid residue. In certain embodiments the engineered amino acid may be a cysteine residue, which can be introduced into specific sites of the antibody via recombinant methods. Site-specificity may be achieved, for example, by substituting a cysteine residue in a particular location to ensure that the cysteine is unpaired (i.e., not available to form an intra- or inter-chain disulfide with a spatially adjacent cysteine). Exemplary sites for insertion of cysteine substitutions include the constant regions and / or Fc regions of an antibody. Methods for inserting cysteine substitutions in an antibody are known in the art and described, for example in Lyons et al.1990 (Lyons, Alan, et al. "Site-specific attachment to recombinant antibodies via introduced surface cysteine residues." Protein Engineering, Design and Selection 3.8 (1990): 703-708), WO 2011 / 005481, WO2014 / 124316, and WO 2015 / 138615, of which the entirety of each is incorporated herein by reference. In certain embodiments, the engineered amino acid may be a selenocysteine, a cysteine analogue, which may be introduced into specific sites of the antibody via recombinant and / or co- translational methods. The selenol group is more nucleophilic than a thiol group and does not require reduction of the antibody. In such cases, linkers may be attached to engineered cysteines or selenocysteines via the conjugation chemistries for cysteine residues discussed above. In certain embodiments, the engineered amino acid may be a tyrosine. In some embodiments, the engineered amino acid may be an unnatural or non-canonical (NCAA) amino acid. By virtue of their orthogonal chemistry, unnatural amino acids enable site-specific Atty. Dkt: OMNI-002WO conjugation of linkers. Unnatural amino acids include, without limitation, p-acetylphenylalanine (pAcF), p-azidomethyl-L-phenylalanine (pAMF), azido-lysine (AzK). As an example, pAcF residues can be conjugates specifically to linkers comprising an oxime moiety. As another example, azide containing pAMF residues can be specifically conjugated to an alkyne-containing linker via Click chemistry. Chemical conjugation of linkers to unnatural amino acids, among other methods, are known in the art and described, for example, in Dennler et al.2015 (Dennler, Patrick, Eliane Fischer, and Roger Schibli. "Antibody conjugates: from heterogeneous populations to defined reagents." Antibodies 4.3 (2015): 197- 224) and Zimmerman et al.2014(Zimmerman ES, Heibeck TH, Gill A, Li X, Murray CJ, Madlansacay MR, et al. Production of site-specific antibody-drug conjugates using optimized non-natural amino acids in a cell-free expression system. Bioconjug Chem.2014; 25:351–61). Cleavable Linkers In some embodiments, the ADC linker is selectively cleavable in vivo. Cleavable linkers comprise a selectively cleavable, unstable, or degradable moiety that enables release of the payload at its intended site of action upon a specific stimulus or process, e.g, a stimulus or process characteristic of a tumor microenvironment or an intracellular compartment. In some cases, cleavage of the linker may be triggered by a chemical stimulus, e.g., a change in pH. In other cases, cleavage of the linker may be triggered by an enzyme. As such, cleavable linkers may be utilized to add an additional dimension of target selectivity in addition to the target specific antibody. Cleavable linkers generally incorporate one or more chemically or enzymatically cleavable moieties, whereas the rest of the linker may remain uncleavable. In some embodiments, the cleavable linker may be a pH sensitive (i.e., acid-labile) linker or comprises a pH sensitive moiety. pH sensitive cleavable linkers and pH sensitive cleavable moieties are stable under alkaline conditions but are sensitive to hydrolysis under acidic conditions. For example, the release of a payload from an acid-labile linker is facilitated by the acidic conditions of the endosome and lysosome, encountered by an ADC following internalization via endocytosis. In addition, tumor microenvironments are often acidic, and pH sensitive moieties can offer an additional dimension of target selectivity for delivery of the cytotoxic payload to tumors. Suitable pH sensitive moieties for incorporation into an acid-labile linker include hydrazone moieties, which are hydrolyzed under acidic conditions. Additional acid labile moieties that may be incorporated into a pH sensitive include carbonate and cis-aconityl moieties. Exemplary cleavable linker types that incorporate pH sensitive moieties include, without limitation, AcBut-like linkers incorporating a hydrazone moiety, MC-like linkers incorporating a hydrazone moiety, and MCC-like linkers incorporating a hydrazone moiety. For example, suitable acid labile linkers incorporating an acid labile hydrazone moiety include the acid-labile Atty. Dkt: OMNI-002WO linkers utilized in gemtuzumab ozogamicin, inotuzumab ozogamicin, PF-06647263, CMD-193, CMB- 401, SGN-15, milatuzumab doxorubicin. In some embodiments, the cleavable linker may be a reducible or glutathione sensitive linker or comprises a reducible or glutathione sensitive moiety. For example, the release of a payload from a reducible linker into the cytosol of a cell is facilitated by the reducing environment and high glutathione concentration of the cytosol, encountered following internalization of an ADC into the cell. Glutathione is present at much higher concentrations intracellularly than in plasma, thus a marked difference in reduction potential exists intracellularly in comparison to plasma in circulation. In addition, glutathione is released during cell replication and thus proliferating cancer cells exhibit high concentrations of glutathione, offering an additional dimension of target-selectivity for delivery of the cytotoxic payload to proliferating cancer cells. A suitable glutathione sensitive moiety for incorporation into a reducible linker is a disulfide moiety. Exemplary cleavable linker types that incorporate glutathione sensitive moieties include, without limitation, AcBut-like linkers incorporating a disulfide moiety, MC-like linkers incorporating a disulfide moiety, SPDB-like linkers, and sulfo-SPDB-like linkers. For example, suitable reducible linkers incorporating an reducible moiety include the reducible linkers utilized in gemtuzumab ozogamicin, inotuzumab ozogamicin, cantuzumab mertansine, bivatuzumab mertansine, lorvotuzumab mertansine, MLN2704, SAR566658, cantuzumab ravtansine, IMGN388, HKT288, BIIB015, LY3076226, SAR428926, coltuximab ravtansine, AVE9633, DHES0815A, PF-06647263, CMD-193, and CMB-401. In some embodiments, the cleavable linker may be a proteolytically-cleavable linker or comprises a proteolytically-cleavable moiety. Proteolytically-cleavable linkers comprise peptide motifs that are specifically targeted and hydrolyzed by intracellular proteolytic enzymes (e.g., proteases). Notably, intracellular proteases, e.g., lysosomal proteases, generally have poor activity in the unfavorably alkaline conditions of circulating plasma in comparison to their activity in the acidic conditions of the endosome and lysosome. For example, the release of a payload from a proteolytically- cleavable linker is facilitated by the high concentration of proteases (e.g., cathepsin B) in the acidic endosomal and lysosomal compartments encountered by an ADC following internalization by endocytosis. In addition, proteases, such as cathepsin B, are often overexpressed in or secreted by tumor cells, offering an additional dimension of target-selectivity for delivery of the cytotoxic payload to cancerous cells. In certain embodiments, the proteolytically-cleavable moiety is a dipeptide moiety. Suitable dipeptide moieties for incorporation into a proteolytically-cleavable linker include, without limitation, valine-citrulline (Val-Cit), valine-alanine (Val-Ala), phenylalanine-valine (Phe-Val), and phenylalanine-lysine (Phe-Lys) dipeptide moieties. The Val-Cit dipeptide moiety, for example, can be Atty. Dkt: OMNI-002WO hydrolyzed by the cathepsin B protease. In certain embodiments, the proteolytically-cleavable peptide motif is a tetrapeptide. Suitable tetrapeptides moieties for incorporation into a proteolytically-cleavable linker include glycine-phenylalanine-leucine-glycine (Gly-Phe-Leu-Gly) and alanine-leucine-alanine- leucine (Ala-Lue-Ala-Leu) tetrapeptide moieties. For example, suitable linkers that incorporate proteolytically-cleavable moieties include, without limitation, the dipeptide incorporating linkers utilized in brentuximab vedotin, polatuzumab vedotin, loncastuximab tesirine, enapotamab vedotin, BAY79- 4620, losatuxizumab vedotin, indusatumab vedotin, glembatumumab vedotin, samrotamab vedotin, DLYE5953A, sofituzumab vedotin, DMOT4039A, DMUC4064A, lifastuzumab vedotin, sirtratumab vedotin, vandortuzumab vedotin, CDX-014, pinatuzumab vedotin, AGS67E, iladatuzumab vedotin, DFRF4539A, azintuxizumab vedotin, AbGn-107, PF-06650808, PF-06664178, BMS-986183, SC-004, rovalpituzumab tesirine, SC-002, tamrintamab pamozirine, ADCT-502, rolinsatamab talirine, ADCT- 401, SC-006, SGN-CD70A, SGN-CD19B, MEDI7247, MEDI2228, vadastuximab talirine, SGN- CD123A, SGN-CD352A, BMS-986148, and MDX-1203. In some embodiments, the cleavable linker may be a glycosidase-cleavable linker or comprise a glycosidase-cleavable moiety. Various glycosidase enzymes, such as β-glucuronidase or β-galactosidase, are localized to the acidic lysosomal compartment of a cell. For example, the release of a payload from a glycosidase-cleavable linker is facilitated by the presence of glycosidase enzymes, such as β- glucuronidase or β-galactosidase, in the lysosomal compartment of a cell encountered by an ADC following internalization by endocytosis. In addition, glycosidase enzymes are often overexpressed in or secreted by tumor cells, offering an additional dimension of target-selectivity for delivery of the cytotoxic payload to cancerous cells. In certain embodiments, the glycosidase-cleavable linker is a β-glucuronidase-cleavable linker or comprises a β-glucuronidase-cleavable moiety. The β-glucuronidase- cleavable moiety includes a β-glucuronide moiety that is specifically targeted and hydrolyzed by β-glucuronidase. For example, a suitable linker that incorporates a β-glucuronidase-cleavable moiety includes, without limitation, the β-glucuronidase-cleavable linker utilized in the ADC SGN-CD48A. In certain embodiments, the glycosidase-cleavable linker is a β-galactosidase-cleavable linker or comprises a β-galactosidase-cleavable moiety. β-galactosidase-cleavable linkers are similar to β-glucuronidase- cleavable linkers, but, instead of a β-glucuronide moiety, utilize a β-galactoside moiety that is hydrolyzed by β-galactosidase. In some embodiments, the cleavable linker is a phosphatase-cleavable linker or comprises a phosphatase-cleavable moiety. Acid pyrophosphatases and acid phosphatases are present in the lysosome and hydrolyze pyrophosphates and terminal phosphates, respectively, into alcohols. For example, the release of a payload from a phosphatase-cleavable linker is facilitated by the presence of Atty. Dkt: OMNI-002WO pyrophosphatase and phosphatase enzymes in the lysosomal compartment of a cell encountered by an ADC following internalization by endocytosis. In certain embodiments, the phosphatase-cleavable moiety is pyrophosphate or phosphate moiety. In some instances, a suitable phosphatase-cleavable linker may be covalently linked to the payload via a pyrophosphate or phosphate moiety. In certain embodiments, a cleavable linker may incorporate two or more cleavable moieties that are cleaved in response to different stimuli. For example, a cleavable linker may incorporate an acid- labile and a glutathione-sensitive moiety (e.g., a hydrazone and a disulfide). As another example, the cleavable linker may incorporate a proteolytically-cleavable moiety and a phosphatase-cleavable moiety (e.g., a Val-Cit dipeptide and a phosphate moiety). Cleavable linkers are known in the art and described, for example, in Bargh et al.2019 (Bargh, Jonathan D., et al. "Cleavable linkers in antibody–drug conjugates." Chemical Society Reviews 48.16 (2019): 4361-4374), Sheyi et al.2022 (Sheyi, Rotimi, Beatriz G. de la Torre, and Fernando Albericio. "Linkers: An assurance for controlled delivery of antibody-drug conjugate." Pharmaceutics 14.2 (2022): 396), and Jain et al.2025 (Jain, Nareshkumar, et al. "Current ADC linker chemistry." Pharmaceutical research 32.11 (2015): 3526-3540), the entirety of each being incorporated herein by reference. Non-Cleavable Linkers In some embodiments, the ADC is non-cleavable or substantially non-cleavable in vivo. Non-cleavable linkers comprise stable moieties that prevent enzymatic or chemical degradation and ensure higher stability in circulating plasma than cleavable linker counterparts. Release of payloads from ADCs utilizing non-cleavable linkers relies on lysosomal degradation of the antibody following internalization of the ADC. Exemplary non-cleavable linkers include maleimidocaproyl (MC) linkers, maleimidomethyl cyclohexane-1-carboxylate (MCC) linkers, N-succinimidyl-4-(maleimidomethyl) cyclohexane-1-carboxylate (SMCC) linkers, and derivatives thereof. For example, suitable linkers that incorporate non-cleavable moieties include, without limitation, the non-cleavable linkers utilized in trastuzumab emtansine, PF-06263507, depatuxizumab mafodotin, AGS16F, MEDI-547, vorsetuzumab mafodotin, denintuzumab mafodotin, lupartumab amadotin, aprutumab ixadotin, AMG 172, LOP628, laprituximab emtansine, AMG 595, PCA062, AMG 224, BAT8001, and BAT8003. Non-cleavable linkers are known in the art and described, for example, in Sheyi et al.2022 (Sheyi, Rotimi, Beatriz G. de la Torre, and Fernando Albericio. "Linkers: An assurance for controlled delivery of antibody-drug conjugate." Pharmaceutics 14.2 (2022): 396), and Jain et al.2025 (Jain, Nareshkumar, et al. "Current ADC linker chemistry." Pharmaceutical research 32.11 (2015): 3526-3540), the entirety of each being incorporated herein by reference. Spacers Atty. Dkt: OMNI-002WO In some embodiments, the linker (e.g., a cleavable or non-cleavable linker) may comprise one or more spacer moieties. In some cases, due to the size and / or structure of the payload a spacer may be required to avoid having the payload sterically interfere with the function of a cleavable moiety in the linker, e.g., a cleavable linker where an enzymatically cleavable moiety must remain accessible to the corresponding enzyme. Exemplary spacers for use in a linker include polyethylene glycol (PEG) polymeric moieties. In some instances, cleavage of a cleavable linker may result in the release of undesirable payload adducts when the payload is directly attached to the linker. In such cases a self- immolative spacer moiety may be used to link the payload to the cleavable linker. Self-immolative spacers can spontaneously decompose following disruption of an adjacently linked cleavable-moiety and allowing the release of a chemically unmodified (i.e., lacking undesirable adducts) payload. An exemplary self-immolative spacer for use in the presently described linkers is the p- aminobenzylcarbamate (PABC) spacer. As an example, a PABC linker may be linked to an adjacent cleavable dipeptide moiety through an amide bond. Following proteolytic cleavage of the amide bond, the PABC linker spontaneously decomposes via a 1,6-elimination reaction to release CO2 and aza-quinone methide and the desired payload. Self-immolative spacers are known in the art and reviewed, for example, in Alouane et al.2015 (Alouane, Ahmed, et al. "Self‐immolative spacers: kinetic aspects, structure–property relationships, and applications." Angewandte Chemie International Edition 54.26 (2015): 7492-7509), Bargh et al.2019 (Bargh, Jonathan D., et al. "Cleavable linkers in antibody– drug conjugates." Chemical Society Reviews 48.16 (2019): 4361-4374), Sheyi et al.2022 (Sheyi, Rotimi, Beatriz G. de la Torre, and Fernando Albericio. "Linkers: An assurance for controlled delivery of antibody-drug conjugate." Pharmaceutics 14.2 (2022): 396), of which the entirety of each is incorporated herein by reference. Branched / Polyvalent Linkers In some embodiments, the linker is a branched or polyvalent linker (i.e., link more than one payload molecule to a single site on the antibody). In some cases, the polyvalent linker is selectively cleavable in vivo. Methods of making and using a variety of polyvalent and branched linkers in ADCs are known in the art and described, for example, in WO 2009 / 073445, WO 2010 / 068795, WO 2010 / 138719, WO 2011 / 120053, WO 2011 / 171020, WO 2013 / 096901, WO 2014 / 008375, WO 2014 / 093379, WO 2014 / 093394, WO 2014 / 093640, WO / 2015 / 054659, WO 2018 / 098269, WO 2018 / 237262, WO 2021 / 142199, of which the entirety of each is incorporated herein by reference. Non-covalent linkers In some embodiments, the linker may be a non-covalent linker. For example, in some cases, the non-covalent linker may comprise a first member of a specific binding pair which can non-covalently Atty. Dkt: OMNI-002WO bind to a second member of the specific binding pair that is attached to or incorporated into the payload molecule. Exemplary linkers comprising a first and second member of a specific binding pair, suitable for use in an ADC of the present disclosure, are avidin-biotin linkers. The avidin linker comprises an avidin polypeptide e.g., an avidin, streptavidin, neutravidin) which can bind a biotin moiety attached to or incorporated into the payload molecule (i.e., a biotinylated payload molecule) with high-affinity (e.g., a KD ≈ 10-10to 10-15M). Avidin-based linkers for linking biotinylated payloads to antibodies are known in the art and described, for example, in Xia et al.2009 (Xia, Chun-Fang, Ruben J. Boado, and William M. Pardridge. "Antibody-mediated targeting of siRNA via the human insulin receptor using avidin− biotin technology." Molecular pharmaceutics 6.3 (2009): 747-751), the entirety of which is incorporated herein by reference. In some cases, the linker may be an ionic or electrostatic linker. For example, where the payload molecule exhibits a sufficient charge under the relevant physiological conditions, an oppositely charged linker may be used to link the charged payload to the antibody. For instance, where the payload molecule is negatively charged (e.g., as in cases where the payload is a nucleic acid) the linker may be a positively charged linker. Exemplary positively charged linkers for linking negatively charged payload molecules (e.g., nucleic acid payloads) include, without limitation, poly-arginine linkers, poly-lysine linkers, and protamine linkers. Ionic and electrostatic linkers for linking negatively charged payloads (e.g., nucleic acids) to antibodies are known in the art and described, for example, in Song et al.2005 (Song, Erwei, et al. "Antibody mediated in vivo delivery of small interfering RNAs via cell-surface receptors." Nature biotechnology 23.6 (2005): 709-717), Chandela et al.2019 (Chandela, Akash, and Yoshihito Ueno. "Systemic delivery of small interfering RNA therapeutics: Obstacles and advances." Reviews in Agricultural Science 7 (2019): 10-28), Shi et al.2019 (Shi, Sheng-Jia, et al. "Therapeutic effects of human monoclonal PSMA antibody-mediated TRIM24 siRNA delivery in PSMA-positive castration- resistant prostate cancer." Theranostics 9.5 (2019): 1247), and Lu et al.2013 (Lu, Hua, et al. "Site- specific antibody–polymer conjugates for siRNA delivery." Journal of the American Chemical Society 135.37 (2013): 13885-13891), of which the entirety of each is incorporated herein by reference. In some cases, where the payload is a nucleic acid (e.g., an RNA or DNA oligonucleotide), the linker may be an oligonucleotide designed to specifically hybridize with all, or a portion of, the nucleic acid payload, thereby non-covalently linking the nucleic acid payload to the antibody. Oligonucleotide linkers for linking nucleic acid payloads to an antibody via hybridization are known in the art and described, for example, in Hsu et al.2020 (Hsu, Nai-Shu, et al. "Development of a versatile and modular linker for antibody–drug conjugates based on oligonucleotide strand pairing." Bioconjugate Chemistry 31.7 (2020): 1804-1811) and Dovgan et al.2020 (Dovgan, Igor, et al. "On the use of DNA as a linker in Atty. Dkt: OMNI-002WO antibody-drug conjugates: synthesis, stability and in vitro potency." Scientific Reports 10.1 (2020): 7691), of which the entirety of each is incorporated herein by reference. Masked / Prodrug ADCs In some embodiments, an ADC of the present disclosure may comprise a masked (i.e., prodrug) antibody. Although the antibody of an ADC provides target-specificity to the associated payload, there is still a potential risk for off-target delivery of the payload, e.g., in cases where the antigen targeted by the antibody of the ADC is also expressed in non-target cells or non-target tissues (e.g., non-cancerous cells). In such cases, additional selectivity of the ADC may be achieved by masking, blocking, or otherwise preventing the paratope of the antibody from binding its antigen target (i.e., an inactive, prodrug form) when administered, and unmasking, unblocking, or otherwise allowing the paratope of the antibody to bind its cognate antigen (i.e., an active, drug form) when near the target tissue region (e.g., a tumor). In certain embodiments, the masked ADC may comprise an antibody with an anti-idiotypic mask (e.g., an epitope mimetic). In certain embodiments, the masked ADC may comprise an antibody with a steric mask. The un-masking of the antibody (i.e., conversion from the prodrug to the drug form) may be triggered by any suitable stimulus that differentiates the target tissue from non-target tissues. Masked and / or prodrug antibodies for use in the ADCs of the present disclosure are known in the art and reviewed, for example, in Lucci et al.2021 (Lucchi, Roberta, Jordi Bentanachs, and Benjamí Oller-Salvia. "The masking game: design of activatable antibodies and mimetics for selective therapeutics and cell control." ACS central science 7.5 (2021): 724-738), the entirety of which is incorporated herein by reference. Mask Linkers In certain embodiments, un-masking of the antibody may be triggered by a proteolytic enzyme acting on a cleavable linker polypeptide joining the mask to the antibody. In some cases, the cleavable polypeptide linker is a proteolytically cleavable polypeptide. Upon encountering a target-tissue environment characterized by high levels of active proteolytic enzymes, such as a tumor microenvironment, the proteolytically cleavable linker is cleaved and the mask is released, enabling the antibody to bind its target-antigen. The proteolytically cleavable polypeptide linker may comprise any suitable proteolytic enzyme substrate sequence. Suitable amino acid sequences for use in a proteolytically cleavable linker include substrates for matrix metalloproteinases (MMPs) such as MMP-2 or MMP-9. Cancer-associated proteolytic enzyme substrates are known in the art and described, for example, in Vasiljeva et al.2019 (Vasiljeva, Olga, et al. "The multifaceted roles of tumor-associated proteases and harnessing their activity for prodrug activation." Biological Chemistry 400.8 (2019): 965- Atty. Dkt: OMNI-002WO 977) and Sevenich et al.2014 (Sevenich, Lisa, and Johanna A. Joyce. "Pericellular proteolysis in cancer." Genes & development 28.21 (2014): 2331-2347), of which the entirety of each is incorporated herein by reference Anti-Idiotypic Masks In some embodiments, a masked ADC of the present disclosure comprises an antibody with an anti-idiotypic mask. An anti-idiotypic mask is specific to the paratope of the antibody and interacts with the paratope of the antibody specifically and thus prevents binding of the antibody to its cognate epitope. In certain embodiments, the anti-idiotypic mask is an epitope-mimetic polypeptide, also referred to as a mimotope, that is tethered via a cleavable polypeptide linker to the N-terminus of the antibody and specifically binds the paratope of the antibody. A mimotope or epitope-mimetic polypeptide structurally mimics the cognate epitope and thereby competes with the cognate epitope for binding to the paratope of the antibody. In some cases, the cleavable polypeptide linker is a proteolytically cleavable polypeptide as described above. Upon encountering a target-tissue environment characterized by high levels of active proteolytic enzymes the proteolytically cleavable linker is cleaved and the mimotope polypeptide is released, enabling the antibody to bind its target-antigen. Mimotope polypeptides for use in a masked antibody are known in the art and described, for example, in WO 2009 / 025846, WO 2010 / 081173, WO 2013 / 163631, and Kavanaugh 2020 (Kavanaugh, W. Michael. "Antibody prodrugs for cancer." Expert opinion on biological therapy 20.2 (2020): 163-171), of which the entirety of each is incorporated herein by reference. In certain embodiments, the anti-idiotypic mask is an antigen-binding polypeptide or may comprise an antigen-binding fragment polypeptide that is specific for the paratope or variable-fragment region of the antibody in such a way that the cognate epitope is occluded from binding the paratope of the antibody. In some cases, the antigen-binding polypeptide mask is bi-specific for a bulky serum protein (e.g., albumin) and for the antibody of the ADC, adding an additional steric hindrance to the binding of the ADC antibody to its cognate epitope. In certain embodiments, the antigen-binding polypeptide mask is tethered via a cleavable polypeptide linker to the N-terminus of the antibody. In some cases, the cleavable polypeptide linker is a proteolytically cleavable polypeptide as described above. Upon encountering a target-tissue environment characterized by high levels of active proteolytic enzymes the proteolytically cleavable linker is cleaved and the antigen-binding polypeptide mask is released, enabling the antibody to bind its target-antigen. Antigen-binding polypeptide masks are known in the art and described, for example, in WO 2019 / 222282, WO 2019 / 222283, WO 2023 / 064945, and Borras et al.2023 (Borras, Anna Mestre, et al. "Generation of an anti-idiotypic affibody-based masking Atty. Dkt: OMNI-002WO domain for conditional activation of EGFR-targeting." New Biotechnology 73 (2023): 9-18), of which the entirety of each is incorporated herein by reference. Steric Masks In some embodiments, a masked ADC of the present disclosure comprises an antibody with an steric mask. A steric mask is not specific to the antibody (e.g., it is not specific to the paratope of variable domains of the antibody) and instead prevents binding of the antibody to its cognate epitope through steric hindrance and physical occlusion of the antibody paratope. In certain embodiments, the steric mask is a polypeptide that specifically binds a bulky serum protein, such that binding of the bulky serum protein sterically inhibits the binding of the antibody to its target antigen, wherein the steric binding mask itself does not bind to the paratope or variable domain of the antibody. The bulky serum protein may be any suitably bulky protein found in high abundance in serum. Exemplary bulky serum proteins that a steric mask polypeptide may specifically bind include, without limitation, albumin, fibrinogen, fibronectin, hemoglobin, transferrin, and immunoglobulins. In some embodiments, the steric mask polypeptide is tethered via a cleavable polypeptide linker to the N-terminus of the antibody. In some cases, the cleavable polypeptide linker is a proteolytically cleavable polypeptide as described above. Upon encountering a target-tissue environment characterized by high levels of active proteolytic enzymes the proteolytically cleavable linker is cleaved and the steric mask polypeptide is released, enabling the antibody to bind its target-antigen. Steric mask polypeptides are known in the art and described, for example, in WO 2013 / 192546 and WO 2014 / 197612A1, of which the entirety of each is incorporated herein by reference. Nucleic acids A nucleic acid (e.g., expression vector) comprising a nucleotide sequence encoding a subject polypeptide is also provided. A subject nucleic acid may be produced by any method. Since the genetic code and recombinant techniques for manipulating nucleic acid are known, the design and production of nucleic acids encoding a subject fusion protein is well within the skill of an artisan. In certain embodiments, standard recombinant DNA technology (Ausubel, et al, Short Protocols in Molecular Biology, 3rd ed., Wiley & Sons, 1995; Sambrook, et al., Molecular Cloning: A Laboratory Manual, Second Edition, (1989) Cold Spring Harbor, N.Y.) methods are used. Purification methods The present disclosure provides methods of producing a subject polypeptide. The methods generally involve culturing, in a culture medium, a host cell that is genetically modified with one or more nucleic acids (e.g., one or more recombinant expression vectors) comprising nucleotide sequences encoding the polypeptide; and isolating the polypeptide from the genetically modified host cell and / or Atty. Dkt: OMNI-002WO the culture medium. A host cell that is genetically modified with one or more nucleic acids (e.g., one or more recombinant expression vectors) comprising nucleotide sequences encoding the polypeptide is also referred to as an “expression host.” As noted above, in some cases, the polypeptide may be encoded in separate nucleic acids (e.g., separate recombinant expression vectors). In some cases, the polypeptide may be encoded in a single nucleic acid (e.g., a single recombinant expression vector). Isolation of the polypeptide from the expression host cell (e.g., from a lysate of the expression host cell) and / or the culture medium in which the host cell is cultured, can be carried out using standard methods of protein purification. For example, a lysate may be prepared of the expression host and the lysate purified using high performance liquid chromatography (HPLC), exclusion chromatography, gel electrophoresis, affinity chromatography, or other purification technique. Alternatively, where the polypeptide is secreted from the expression host cell into the culture medium, the polypeptide can be purified from the culture medium using HPLC, exclusion chromatography, gel electrophoresis, affinity chromatography, or other purification technique. In some cases, the compositions which are used will comprise at least 80% by weight of the desired product (the polypeptide), at least about 85% by weight, at least about 95% by weight, or at least about 99.5% by weight, in relation to contaminants related to the method of preparation of the product and its purification. The percentages can be based upon total protein. Pharmaceutical compositions Also provided is a pharmaceutical composition comprising a polypeptide as described above or a polynucleotide encoding the same (e.g., an RNA) and a pharmaceutically acceptable carrier. In any of these embodiments, the polypeptide in the composition may be a multispecific binding molecule that comprises the domain and at least one other binding domain that binds to a cancer antigen. In some embodiments, the polypeptide may be a BiKE or TriKE, as described above. A wide variety of pharmaceutically acceptable ingredients are known in the art and hence are not discussed in detail herein. Moreover, pharmaceutically acceptable ingredients and compositions have been amply described in a variety of publications, including, but not limited to, A. Gennaro (2000) "Remington: The Science and Practice of Pharmacy", 20th edition, Lippincott, Williams, & Wilkins; Pharmaceutical Dosage Forms and Drug Delivery Systems (1999) H. C. Ansel et al., eds 7thed., Lippincott, Williams, & Wilkins; and Handbook of Pharmaceutical Excipients (2000) A. H. Kibbe et al., eds., 3rded. Amer. Pharmaceutical Assoc. Many other publications describing preparation of biopharmaceutical compositions may be consulted. The composition may be formulated according to the various routes of administration described below. Generally speaking, a polypeptide of this disclosure will be an aqueous liquid and typically will Atty. Dkt: OMNI-002WO be administered via an intravenous infusion. In some cases, the pharmaceutical composition comprising the polypeptide can be admixed with saline (e.g., 0.9% NaCl) prior to IV administration. Thus, the present disclosure provides a sterile composition comprising: a) a polypeptide of the present disclosure; and b) saline (e.g., 0.9% NaCl). Alternatively, it may be administered neat via an intravenous infusion, i.e., without further dilution. Alternatively, the pharmaceutical composition may be formulated so as to be administered by injection. Methods Also provided herein are a variety of methods. In some embodiments the method may increase binding between an NK cell (e.g., a CD3- / CD56+ cell that is also CD7+ / CD127- / NKp46+ / T-bet+ / Eomes+) and a cancer cell. These embodiments may comprise incubating the NK cell and a cancer cell with a subject polypeptide, wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain that binds to a cancer antigen on the cancer cell. As noted above, in these embodiments, the polypeptide may bind to both the NK cell and the cancer cell, which may cause activation of the NK cell and subsequent death of the cancer cell. This reaction may occur in vitro, in vivo or ex vivo. A method of increasing binding between an NK cell and a virally-infected cell is also provided. This method may comprise incubating the NK cell and a virally-infected cell with a subject polypeptide , wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain that binds to a viral antigen on the virally-infected cell. in these embodiments, the polypeptide may bind to both the NK cell and the virally-infected cell, which may cause activation of the NK cell and subsequent death of the virally-infected cell. This reaction may occur in vitro, in vivo or ex vivo. In related embodiments, the method may comprise contacting the cancer with an NK cell (e.g., a CD3- / CD56+ cell that is also CD7+ / CD127- / NKp46+ / T-bet+ / Eomes+) and a subject polypeptide, wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain that binds to a cancer antigen on the cancer cell. As noted above, in these embodiments, the polypeptide may bind to both the NK cell and the cancer cell, which may cause activation of the NK cell and subsequent death of the cancer cell. This reaction may occur in vitro, in vivo or ex vivo. A method of killing a virally-infected cell is also provided. In these embodiments, the method may comprise contacting the virally-infected cell with an NK cell and a subject polypeptide, wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding Atty. Dkt: OMNI-002WO domain or the knob domain and at least one other binding domain that binds to a viral antigen on the virally-infected cell. In these embodiments, the polypeptide may bind to both the NK cell and the virally- infected cell, which may cause activation of the NK cell and subsequent death of the virally-infected cell. This reaction may occur in vitro, in vivo or ex vivo. A method of treatment is also provided. In these embodiments, the method may comprise administering a subject polypeptide or a polynucleotide encoding the same (e.g., an RNA) to a subject that has cancer, wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain that binds to a cancer antigen on the cancer cell. The cancer antigen may be selected based on the cancer being treated. Suitable cancer antigen / cancers include: CD19, CD20 or BCMA (for B-cell malignancies, including acute myeloid leukemia (AML), multiple myeloma (MM), B-cell acute lymphoblastic leukemia (B-ALL), lymphoma, etc.), ALPP (for, e.g., ovarian and endometrial cancer), CS1 (SLAMF7) (for, e.g., R / R multiple myeloma), CLDN18.2 (for, e.g., pancreatic and gastric adenocarcinoma, gastric cancer), AXL (for, e.g., renal cell carcinoma), ROR2 (for, e.g., renal cell carcinoma), TM4SF1 (for, e.g., advanced solid tumors), ICAM-1 (for, e.g., anaplastic thyroid cancer), L1CAM (CD171) (for, e.g., neuroblastoma, ganglioneuroblastoma), CD4 (for, e.g., T-cell lymphoma, T-cell leukemia), CD5 (T-cell acute lymphoblastic lymphoma, non-Hodgkin T-cell lymphoma), CD7 (for, e.g., T-cell acute lymphoblastic lymphoma, T-cell acute lymphoblastic leukemia, non-Hodgkin T-cell lymphoma), CD10 (for, e.g., CD19-negative B-cell malignancies), CD38 (for, e.g., CD19-negative B-cell malignancies), CEA (for, e.g., lung, colorectal, liver, pancreatic, gastric, and breast cancer), FLT3 (for, e.g., R / R acute myeloid leukemia), CD70 (for, e.g., pancreatic, renal cell, ovarian, and breast cancer, melanoma), CD30 (for, e.g., Hodgkin lymphoma), CD37 (for leukemia and B-cell, T-cell, and Non-Hodgkin lymphoma), CD147 (for, e.g., glioblastoma). Alternatively, the method of treatment may comprise administering a subject polypeptide or a polynucleotide encoding the same (e.g., an RNA) to a subject that has a viral infection, wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain that binds to a viral antigen on a virally-infected cell. Subjects suitable for treatment with a method include individuals who have cancer, including individuals who have been diagnosed as having cancer, individuals who have been treated for cancer but who failed to respond to the treatment, and individuals who have been treated for cancer and who initially responded but subsequently became refractory to the treatment and / or whose disease progressed while on the prior treatment. Atty. Dkt: OMNI-002WO Cancers that can be treated with a method include any cancer that can be targeted with the present polypeptide. Cancers that can be treated with a method include carcinomas, sarcomas, melanoma, leukemias, lymphomas and multiple myeloma. Cancers that can be treated with a method include solid tumors, and cancers that begin in blood-forming tissue, i.e., hematological cancers such as leukemias, lymphomas and multiple myeloma. Cancers that can be treated with a method include metastatic cancers. Carcinomas that can treated by a method disclosed herein include, but are not limited to, esophageal carcinoma, hepatocellular carcinoma, basal cell carcinoma (a form of skin cancer), squamous cell carcinoma (various tissues), bladder carcinoma, including transitional cell carcinoma (a malignant neoplasm of the bladder), bronchogenic carcinoma, colon carcinoma, colorectal carcinoma, gastric carcinoma, lung carcinoma, including small cell carcinoma and non-small cell carcinoma of the lung, adrenocortical carcinoma, thyroid carcinoma, pancreatic carcinoma, breast carcinoma, ovarian carcinoma, prostate carcinoma, adenocarcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma, papillary adenocarcinoma, cystadenocarcinoma, medullary carcinoma, renal cell carcinoma, ductal carcinoma in situ or bile duct carcinoma, choriocarcinoma, seminoma, embryonal carcinoma, Wilm's tumor, cervical carcinoma, uterine carcinoma, testicular carcinoma, osteogenic carcinoma, epithelial carcinoma, and nasopharyngeal carcinoma. Sarcomas that can be treated by a method disclosed herein include, but are not limited to, fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, chordoma, osteogenic sarcoma, osteosarcoma, angiosarcoma, endotheliosarcoma, lymphangiosarcoma, lymphangioendotheliosarcoma, synovioma, mesothelioma, Ewing's sarcoma, leiomyosarcoma, rhabdomyosarcoma, and other soft tissue sarcomas. Other solid tumors that can be treated by a method disclosed herein include, but are not limited to, glioma, astrocytoma, medulloblastoma, craniopharyngioma, ependymoma, pinealoma, hemangioblastoma, acoustic neuroma, oligodendroglioma, menangioma, melanoma, neuroblastoma, and retinoblastoma. Leukemias that can be amenable to therapy by a method disclosed herein include, but are not limited to, a) chronic myeloproliferative syndromes (neoplastic disorders of multipotential hematopoietic stem cells); b) acute myelogenous leukemias (neoplastic transformation of a multipotential hematopoietic stem cell or a hematopoietic cell of restricted lineage potential; c) chronic lymphocytic leukemias (CLL; clonal proliferation of immunologically immature and functionally incompetent small lymphocytes), including B-cell CLL, T-cell CLL prolymphocytic leukemia, and hairy cell leukemia; and d) acute lymphoblastic leukemias (characterized by accumulation of lymphoblasts). Lymphomas that can be treated using a subject method include, but are not limited to, B-cell lymphomas (e.g., Burkitt's lymphoma); Hodgkin's lymphoma; non-Hodgkin's lymphoma, and the like. Atty. Dkt: OMNI-002WO Other cancers that can be treated according to the methods disclosed herein include atypical meningioma, islet cell carcinoma, medullary carcinoma of the thyroid, mesenchymoma, hepatocellular carcinoma, hepatoblastoma, clear cell carcinoma of the kidney, and neurofibroma mediastinum.In some cases, an “effective amount” of a polypeptide or a polynucleotide encoding the same (e.g., an RNA) is an amount that, when administered in one or more doses to an individual in need thereof, reduces the number of cancer cells in the individual. For example, in some cases, an “effective amount” of a polypeptide or a polynucleotide encoding the same (e.g., an RNA)is an amount that, when administered in one or more doses to an individual in need thereof, reduces the number of cancer cells in the individual by at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 95%, compared to the number of cancer cells in the individual before administration of the polypeptide, or in the absence of administration with the polypeptide. In some cases, an “effective amount” of a polypeptide or a polynucleotide encoding the same (e.g., an RNA) is an amount that, when administered in one or more doses to an individual in need thereof, reduces the number of cancer cells in the individual to undetectable levels. In some cases, an “effective amount” of a polypeptide or a polynucleotide encoding the same (e.g., an RNA) is an amount that, when administered in one or more doses to an individual in need thereof, reduces the tumor mass / tumor volume in the individual. In some cases, an “effective amount” of a polypeptide is an amount that, when administered in one or more doses to an individual in need thereof, increases survival time of the individual. For example, in some cases, an “effective amount” of a polypeptide or a polynucleotide encoding the same (e.g., an RNA) is an amount that, when administered in one or more doses to an individual in need thereof, increases survival time of the individual by at least 1 month, at least 2 months, at least 3 months, from 3 months to 6 months, from 6 months to 1 year, from 1 year to 2 years, from 2 years to 5 years, from 5 years to 10 years, or more than 10 years, compared to the expected survival time of the individual in the absence of administration with the polypeptide or a polynucleotide encoding the same (e.g., an RNA). Conventional and pharmaceutically acceptable routes of administration include intratumoral, peritumoral, intramuscular, intralymphatic, intratracheal, intracranial, intraventricular, subcutaneous, intradermal, topical application, intravenous, intraarterial, rectal, nasal, oral, and other enteral and parenteral routes of administration. As noted above, a pharmaceutical composition comprising a polypeptide or a polynucleotide encoding the same (e.g., an RNA) typically will be administered intravenously, but may also be administered by other routes that involve injection. In any embodiment, the polypeptide may be administered to the subject by administering a polynucleotide (e.g., an RNA) encoding the polypeptide to a patient. See, e.g., van Hoecke et al (Journal Atty. Dkt: OMNI-002WO of Translational Medicine 201917: 54, Deal et al (Vaccines 20219: 108), Tai et al (Nature Communications 202314: 8042) and Schlake et al (Molecular Therapy 201927: P773-784) for reviews of this category of therapeutic. Combination therapy In some cases, the polypeptide or a polynucleotide encoding the same (e.g., an RNA) may be administered along with at least one additional therapeutic agent or therapeutic treatment (together or sequentially). Suitable additional therapeutic agents include, but are not limited to, a small molecule cancer chemotherapeutic agent, and an immune checkpoint inhibitor. Suitable additional therapeutic treatments include, e.g., radiation, surgery (e.g., surgical resection of a tumor), and the like. A treatment method of the present disclosure can comprise co-administration of a polypeptide or a polynucleotide encoding the same (e.g., an RNA) and at least one additional therapeutic agent. By “co- administration” is meant that both a polypeptide and at least one additional therapeutic agent are administered to an individual, although not necessarily at the same time, in order to achieve a therapeutic effect that is the result of having administered both the polypeptide and the at least one additional therapeutic agent. The administration of the polypeptide and the at least one additional therapeutic agent can be substantially simultaneous, e.g., the polypeptide can be administered to an individual within about 1 minute to about 24 hours (e.g., within about 1 minute, within about 5 minutes, within about 15 minutes, within about 30 minutes, within about 1 hour, within about 4 hours, within about 8 hours, within about 12 hours, or within about 24 hours) of administration of the at least one additional therapeutic agent. In some cases, a polypeptide of the present disclosure is administered to an individual who is undergoing treatment with, or who has undergone treatment with, the at least one additional therapeutic agent. The administration of the polypeptide can occur at different times and / or at different frequencies. In some cases, the subject is an individual undergoing treatment with an immune checkpoint inhibitor. In some cases, the subject is an individual who has undergone treatment with an immune checkpoint inhibitor, but whose disease has progressed despite having received such treatment. In some cases, the subject is an individual who is undergoing treatment with, or who has undergone treatment with, a cancer chemotherapeutic agent. In some cases, the subject is an individual who is preparing to undergo treatment with, is undergoing treatment with, or who has undergone treatment with, an immune checkpoint inhibitor. In some cases, the subject is an individual who is preparing to undergo treatment with, is undergoing treatment with, or who has undergone treatment with, a cancer chemotherapeutic agent, radiation treatment, surgery, and / or treatment with another therapeutic agent. In some cases, a Atty. Dkt: OMNI-002WO pharmaceutical composition comprising the polypeptide is administered in the adjuvant or neoadjuvant setting. Exemplary immune checkpoint inhibitors include inhibitors that target an immune checkpoint polypeptide such as CD27, CD28, CD40, CD122, CD96, CD73, CD47, OX40, GITR, CSF1R, JAK, PI3K delta, PI3K gamma, TAM, arginase, CD137 (also known as 4-1BB), ICOS, A2AR, B7-H3, B7-H4, BTLA, CTLA-4, LAG3, TIM3, VISTA, CD96, TIGIT, CD122, PD-1, PD-L1 and PD-L2. In some cases, the immune checkpoint polypeptide is a stimulatory checkpoint molecule selected from CD27, CD28, CD40, ICOS, OX40, GITR, CD122 and CD137. In some cases, the immune checkpoint polypeptide is an inhibitory checkpoint molecule selected from A2AR, B7-H3, B7-H4, BTLA, CTLA-4, IDO, KIR, LAG3, PD-1, TIM3, CD96, TIGIT and VISTA. Co-therapies include for example, (a) anthracycline therapy (e.g., by administering daunomycin, doxorubicin, or mitoxantrone), (b) alkylating agent therapy (e.g., by administering mechlorethane, cyclophosphamide, ifosfamide, melphalan, cisplatin, carboplatin, nitrosourea, dacarbazine and procarbazine or busulfan), (c) topoisomerase II inhibitor therapy (e.g., by administering etoposide or teniposide), (d) bleomycin therapy, (e) anti-metabolite therapy (e.g., by administering methotrexate, 5- fluorocil, cytarabine, 6-mercaptopurine or 6-thioguanine), (f) vinca alkyloid therapy (e.g., by administering vincristine or vinblastine), (g) steroid therapy (e.g., by administering prednisone or dexamethasone and (h) radiation treatment, etc. Alternative therapies include targeted therapies and non- targeted chemotherapies, where targeted therapy includes treatment with erlotinib (Tarceva), afatinib (Gilotrif), gefitinib (Iressa) or osimertinib (Tagrisso) which may be administered to patients having an activating mutation in EGFR, crizotinib (Xalkori), ceritinib (Zykadia), alectinib (Alecensa) or brigatinib (Alunbrig) which may be administered to patients having an ALK fusion, crizotinib (Xalkori), entrectinib (RXDX-101), lorlatinib (PF-06463922), crizotinib (Xalkori), entrectinib (RXDX-101), lorlatinib (PF-06463922), ropotrectinib (TPX-0005), DS-6051b, ceritinib, ensartinib or cabozantinib which may be administered to patients having an ROS1 fusion, or dabrafenib (Tafinlar) or trametinib (Mekinist) which may be administered to patients having an activating mutation in BRAF. Many other actionable mutations are known. If the patient is going to be switched to a non-targeted chemotherapy, the therapy may be, for example, a platinum-based doublet chemotherapy (in which the platinum-based doublet chemotherapy may comprise a platinum-based agent selected from cisplatin (CDDP), carboplatin (CBDCA), and nedaplatin (CDGP)) and one third-generation agent (selected from docetaxel (DTX), paclitaxel (PTX), vinorelbine (VNR), gemcitabine (GEM), irinotecan (CPT-11), pemetrexed (PEM), and tegafur gimeracil oteracil (S1)). Atty. Dkt: OMNI-002WO SEQUENCE AND DATA TABLES The appendix of this disclosure provides sequences and data that are referred to elsewhere in the disclosure. A brief description of the tables found in the appendix can be found below. Table 1 provides the CDR sequences of 96 VHH domain antibodies that were raised in an engineered chicken (referred to as an OmnidAb chicken); and bind to NKp46. Table 2 provides the full sequences of the variable domains of the antibodies listed in Table 1. Table 3 provides the heavy chain CDR sequences of 245 antibodies that were generated by a fixed light chain rat, i.e., a rat referred to as an OMNIFLIC®rat (OmniAb, Inc.) in which the light chain has limited diversification. Table 4 provides the full sequences of the heavy chain variable domains of the rat antibodies listed in Table 3. The heavy chains whose sequences are listed in Tables 3 and 4 all pair with the same light chain (a “common” light chain) to produce antibodies that bind to NKp46. The light chain CDRs of the antibodies listed in Tables 3 and 4 have the following sequences: CDRL1: QSVSSN (SEQ ID NO:2212), CDRL2: GAS and CDRL3: QQYNNWPWT (SEQ ID NO:2213). The full sequence of the light chain variable domain of the antibodies listed in Tables 3 and 4 is: EIVMTQSPATLSVSPGERATLSCRASQSVSSNLAWYQQKPGQAPRLLIYGASTRATGIPA RFSGSGSGTEFTLTISSLQSEDFAVYYCQQYNNWPWTFGQGTKVEIK (SEQ ID NO:2214). Table 5 provides the dissociation constants for the NKp46 antibodies listed in Tables 3 and 4, as measured by Surface Plasmon Resonance (SPR). Table 6 provides the heavy chain CDR sequences of 170 antibodies that were generated by a fixed light chain chicken, i.e., a chicken referred to as an “OmniClic chicken” in which the light chain has limited diversification. Table 7 provides the full sequences of the heavy chain variable domains of the chicken antibodies listed in Table 6. The heavy chains whose sequences are listed in Tables 6 and 7 all pair with the same light chain (a “common” light chain) to produce antibodies that bind to NKp46. The light chain CDRs of the antibodies listed in Tables 6 and 7 have the following sequences: CDRL1: QSVSSN (SEQ ID NO:2215), CDRL2: GAS and CDRL3: QQYNNWPPWT (SEQ ID NO:2216). The full sequence of the light chain variable domain of the antibodies listed in Tables 6 and 7 is: EIVMTQSPATLSVSPGERATLSCRASQSVSSNLAWYQQKPGQAPRLLIYGASTRATGIPA RFSGSGSGTEFTLTISSLQSEDFAVYYCQQYNNWPPWTFGQGTKVEIK (SEQ ID NO:2217). Atty. Dkt: OMNI-002WO Table 8 provides the dissociation constants (for binding to NKp46) for the antibodies listed in Tables 6 and 7, as measured by SPR. Table 9 provides the sequences of the ultralong heavy chain CDR3s from 9 bovine antibodies that bind to NKp46. Sequences corresponding to the knob domain are underlined in this table. Table 10 provides the CDR sequences of 35 additional VHH domain antibodies that were raised in an engineered chicken (referred to as an “OmnidAb chicken; Crystal Bioscience, Inc.) and bind to NKp46. Table 11 provides the full sequences of the variable domains of the antibodies listed in Table 10. Antibodies CL-2491, CL-27978, CL-27965, CL-2486, CL-27182, CL-25178, CL-25092, CL- 25992, CL-25883, CL-25880, CL-26579, CL-8869, CL-8953, CL-8855, CL-8909, CL-28043, CL-2425, NGS-03 (antibody SK5 in Table 9), NGS-02 (antibody SK7 in Table 9), NGS-118 and NGS-145 were selected for follow-up studies based on their ability to induce ADCC as an EGFR bispecific, the epitope to which they bind, or another attribute (e.g., affinity). Other antibodies may be selected in addition to or in place of any of these antibodies. Table 12 below is a look-up table that links the names of the antibodies described in the examples section of this disclosure with clone IDs, as listed in Tables 1-11. Ab name Clone IDM12-C06CL-24938M14-C12CL-25178L 2426 2 9 134 5 679 0 125 1 691 7 Atty. Dkt: OMNI-002WO M17-B01 CL-27170 M5-A03 CL-3473M16-C05CL-8004M17-B02CL-27178M5-A08CL-3513M16-D02CL-7981 EXAMPLESThe following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use the present invention, and are not intended to limit the scope of what the inventors regard as their invention nor are they intended to represent that the experiments below are all or the only experiments performed. Efforts have been made to ensure Atty. Dkt: OMNI-002WO accuracy with respect to numbers used (e.g. amounts, temperature, etc.) but some experimental errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, molecular weight is average molecular weight, temperature is in degrees Celsius, and pressure is at or near atmospheric. Standard abbreviations may be used, e.g., AA = amino acid, AC-SINS = affinity-capture self-interaction nanoparticle spectroscopy, aSEC = analytical size exclusion chromatography, BiP = immunoglobulin binding protein, bp = base pair, BRL = buffalo rat liver, BSA = bovine serum albumin, CDR = complementarity determining region, CH = heavy chain constant domain, CHO = Chinese hamster ovary, cJH = chicken JH gene, CL = light chain constant domain, cVH = chicken VH gene, ELISA = enzyme-linked immunosorbent assay, FACS = fluorescence-activated cell sorting, Fc = fragment crystallizable, FCS = fetal calf serum, FD = final draw, FDA = Food and Drug Administration, FR = fragment region, GC = gene conversion, GEM = gel encapsulated microenvironment, GFP = green fluorescent protein, GRAVY = grand average of hydropathy, GRN = granulin domain, HcAb = heavy chain only antibodies, HLA = human leukocyte antigen, HPLC = high performance liquid chromatography, HRP = horse radish peroxidase, ID = identification, IFNγ = interferon gamma, IgG = immunoglobulin G, IgH = immunoglobulin heavy chain, IgL = immunoglobulin light chain, IgM = immunoglobulin M, IgNAR = immunoglobulin new antigen receptor, IgY = immunoglobulin Y, IMGT = international ImMunoGeneTics information system, KD = equilibrium dissociation constant, KO = knock out, mAb = monoclonal antibody, MFI = mean fluorescence intensity, MHC = major histocompatibility complex, mRNA = messenger ribonucleic acid, n / d = not determined, NK = natural killer, PBMC = peripheral blood mononuclear cell, PBS = phosphate-buffered saline, PGC = primordial germ cell, PGRN = progranulin, PI = pre-immune, P-VHH = pseudogene of variable heavy domain of heavy chain OmnidAb transgene, qPCR = quantitative polymerase chain reaction, RT-PCR = reverse transcription polymerase chain reaction, scFv = single chain variable fragment, sdAb = single domain antibodies, SDS-PAGE = sodium dodecyl sulfate polyacrylamide gel electrophoresis, SHM = somatic hypermutation, Tagg= aggregation temperature, TCR = T-cell receptor, tLCi = truncated light chain transgene, Tm= melting temperature, VH = variable domain of heavy chain, VHH = variable heavy domain of heavy chain-only antibody, VHH3 = variable heavy domain of heavy chain OmnidAb transgene, VL = variable domain of light chain, WT = wild-type. EXAMPLE 1 GENERATION AND CHARACTERIZATION OF ANTI-NKP46 VHH ANTIBODIES Anti-NKp46 monoclonal antibodies were generated using transgenic chickens that are engineered to express VHH antibodies. These chickens have been genetically modified with a transgene Atty. Dkt: OMNI-002WO expressing a human single domain VH based on VH3-23, inserted into the chicken heavy chain immunoglobulin locus and spliced to the endogenous chicken constant regions. Upstream of the single prerearranged VH gene is an array of 14 pseudogenes with frameworks 1-3 identical in DNA sequence to that of the functional VH. Immunization Three transgenic chickens (bird numbers 72766, 72767, 72773) were immunized with 100 ug of NKp46 ECD protein, which was fused in-frame with a T cell epitope tag and a His tag. The birds were given a prime (in complete Freund's adjuvant) followed by 2 boosts (in incomplete Freund's adjuvant) IM, and a final IV boost without adjuvant (4 injections total, 100 ug protein each injection). Plasma immunoglobulin titer in the immunized birds was monitored by ELISA. NKp46-His protein (and negative control protein progranulin-His) were coated at 50uL / well onto ELISA plates at 2ug / mL in PBS overnight at 4C. Wells were blocked with 3% skim milk in PBS blocking buffer (BB) at 150uL / well for 1 hour at room temperature. The plate was washed with PBS+0.5% Tween 20 (PBST) using the plate washer (5 washes). Serum was diluted in blocking buffer (1:500 dilution, followed by 5-fold serial dilution). Serum samples were applied to the plate at 50uL / well and incubated for 1 hour at room temperature. The plate was washed with PBST using the plate washer. Anti-chicken IgM-HRP was diluted to 1:5000 in blocking buffer and applied to the plate at 50uL / well. Secondary was incubated for 1 hour at room temperature. The plate was washed with PBST using the plate washer. TMB substrate was applied to the wells at 50uL / well and substrate developed for 10 minutes at room temperature. Color development was stopped with 50uL / well 1N HCl. The plate was read at 450nm using the BioTek plate reader. Screening Birds 72773 and 72766 were screened for sdAb monoclonal antibodies using GEM technology for single B cell screening (Mettler-Izquierdo, S. Microscopy (Oxf).2016;65:341–52. 72766 and 72767 were screened using the xPloration® high-throughput B cell screening platform (OmniAb, Inc.). Beads were coated with NKp46 ECD protein and used to screen for single B cells secreting antibody that bound to the beads. Positive cells were picked for downstream cloning of the sdAb antibody. Antibody cloning Atty. Dkt: OMNI-002WO Individual B cells (from either GEMs or xPloration) were placed in individual wells of a 96-well plate and subjected to a one-step reverse transcription-PCR amplification of the sdAb heavy chain variable region. A Qiagen One-step kit was used for the RT-PCR reaction. Reverse transcription was chVH-F9 (in 5’ UTR of the heavy chain transcript) CACCAGTCGGCTCCGCAACCATG (SEQ ID NO:2218) cIgM-CH2-R (in the CH2 domain of the IgM constant region) GGGGTGCATGGTGACGAAAAG (SEQ ID NO:2219) PCR conditions for amplifying the V regions: Initial denaturation: 95°, 2 min Denature: 95°, 15 sec Anneal: 58° 30 sec Extend: 68°, 1 min 39 cycles Final Extension: 68°, 10 min After amplification, PCR reactions were run on an agarose gel and the variable region amplicons were pooled and gel purified. The amplicons were cloned as a pool into a modified pcDNA3.4 vector containing a human Fc sequence. The sdAb variable regions were cloned in-frame into the vector using In-Fusion and the cloning reaction was transformed into competent E coli. Single bacterial colonies were picked and miniprep DNA prepared in a 96 well plate array. Depending on how many of the original B cells were amplified, either one or two 96-well plates of colonies were picked for DNA preparation. Miniprep DNA was tranfected into HEK293 cells in a deepwell format. After several days, cell supernatant containing expressed sdAb-Fc antibodies was harvested and tested in ELISA for binding. Positive clones were sequenced by Sanger sequencing with three primers to cover the entire sdAb-Fc insert and the sdAb sequences assembled into contigs for each clone. Unique clones were then re-tested in ELISA (confirmatory), see below. The sequences of the VHH CDRs of 96 of these antibodies are shown in Table 1. The full length variable domains for these antibodies are shown in Table 2. Selected antibodies were tested by ELISA. In this assay, antibodies were normalized to a concentration of 1 ug / ml and then 5-fold serially diluted to 0.2, 0.04 and 0.008 ul / ml (dilutions 1 through 4). Plates were coated with 2ug / mL of NKp46-His protein diluted in PBS at 50uL / well and incubated for 1 hour at room temperature. Atty. Dkt: OMNI-002WO Coated plates were blocked at 150uL / well with 3% milk in PBS for 1 hour at room temperature. Sample supernatants were diluted in blocking buffer as described above and applied to the blocked plates at 50uL / well and incubated for 1 hour at room temperature. Plates were washed with an AquaMax plate washer at 350uL / well 5 times. Secondary (rabbit anti-human Fc-HRP diluted to 1:5,000 in blocking buffer) was applied at 50uL / well and incubated at room temperature for 1 hour. Plates were washed as before. TMB substrate was applied at 50uL / well and allowed to develop for 10 minutes at room temperature. The reaction was stopped by applying 50uL / well 1N HCl. Plates were read using the BioTek plate reader at 450nm absorbance. This data is shown below: ELISA (Confirmatory) : AR-139 (72767 3 f ELISA AG 35 NK 46 n Atty. Dkt: OMNI-002WO CL-4993 2.368 2.339 2.136 1.308 ELISA (Confirmatory) : AR-102 (72766 n Atty. Dkt: OMNI-002WO CL-3475 3.3 3.005 2.591 1.373 CL-3473 3.648 3.386 2.83 1.623 n Atty. Dkt: OMNI-002WO Binding affinities of the antibodies to NKp46 ECD were determined by Surface Plasmon Resonance (SPR) using an LSA instrument (Carterra, Inc.) in a “capture kinetic” assay format using an HC30M chip (Carterra) surface amine-crosslinked with a rabbit anti-human IgG Fc-specific polyclonal (Rockland) as the capture reagent. Using the 96-printhead, antibodies, which were diluted up to 100-fold in 10 mM HEPES pH 7.4, 150 mM NaCl, 3 mM EDTA, and 0.05% Tween-20 (HBSTE), were captured onto the anti-Human IgG Fc chip surface as ligands. The chip surface was then blocked with an isotype control followed by multiple injections of the running buffer (HBSTE + 0.5 mg / mL BSA) before the kinetics assay. Recombinant human NKp46 ECD was prepared as a 3-fold dilution series spanning 0.4 nM – 300 nM and samples were injected for 10 min each in ascending concentrations, allowing a 15-min dissociation phase following each association phase, in a non-regenerative manner. The Carterra Kinetics software was used to process and analyze the data of each antibody globally by fitting the sensorgrams with a Langmuir 1:1 binding model. The affinity, or equilibrium dissociation constant (KD) for NKp46 ECD interacting with each captured mAb, was determined by the ratio of the kinetic rate constants, KD = kd / ka. Results of this assay are shown below: Carterra LSA (data only) : AR-452 (72767-M9 kinetics) : AG-35 Atty. Dkt: OMNI-002WO CL-3608 1.56E-07 CL-3607 4.63E-08 - Carterra LSA (data only) : AR-212 e- 6 Atty. Dkt: OMNI-002WO CL-2455 2.76E-07 CL-2450 1.90E-07 1.75E-07 Select on Nimbus using Protein A PhyTips. Samples were eluted with 50 mM Citrate Buffer, 150 mM NaCl, and neutralized with a 1:5 ratio of 500 mM Na2HPO4pH 9 Buffer. Samples were then desalted into PBS. Purified material was spun down at 10000 rpm for 3 minutes to pellet down any insoluble material. Then samples were run on an Unchained Labs Uncle instrument using Full-spectrum Fluorescence, Static Light Scattering, and Dynamic Light Scattering to determine Tm, Tagg, and monodispersity, respectively. Samples were run from 25° C to 95° C with a ramp rate of 0.3 C / min, and analyzed by monitoring change in the absorbance ratio of 350 / 330 nm. DLS was captured at 25° C with an incubation time of 180 sec, with a total of 10 acquisitions, each 10 seconds long. Results of this assay are shown below. Clone ID Tm1 (°C) Tagg 266 (°C) CL-3473 6608 7987 Atty. Dkt: OMNI-002WO CL-3557 70.18 72.56 CL-3558 68.42 76.86 EXAMPLE 2 GENERATION AND CHARACTERIZATION OF HUMAN ANTI-NKP46 ANTIBODIES IN A TRANSGENIC RAT Anti-NKp46 monoclonal antibodies were generated using fixed light chain human transgenic rats (OmniFlic rats); see, e.g., Harris et al (Front Immunol.201824:9:889)) that expresses human antibodies comprising a diverse repertoire of heavy chains with a single common rearranged kappa light chain (IgKV3-15-JK1). Atty. Dkt: OMNI-002WO The sequences of 245 of those antibodies are set forth in Tables 3 and 4. Binding data for the antibodies are set forth in Table 5. EXAMPLE 3 GENERATION AND CHARACTERIZATION OF HUMAN ANTI-NKP46 ANTIBODIES IN TRANSGENIC CHICKEN Anti-NKp46 monoclonal antibodies were generated using fixed light chain human transgenic chickens (OmniClic chickens; see, e.g., Ching et al (MAbs.2021; 13(1): 1862451)) that expresses diverse human heavy chain variable regions capable of high-affinity antigen-specific binding and broad epitope diversity when paired with the germline human kappa light chain (the VK3-15 light chain). The sequences of 170 of those antibodies are set forth in Tables 6 and 7. Binding data for the antibodies are set forth in Table 8. EXAMPLE 4 GENERATION ANDCHARACTERIZATION OFBOVINEULTRA-LONGHCSCDR3THATBIND TONKP46 A cow was immunized with NKp46 using conventional methods. cDNA sequences encoding ultralong H3 heavy chains were amplified from the cow, expressed, and tested for binding to NKp46. The sequences of the heavy chain CDR3 of 9 antibodies that bind to NKp46 are set forth in Table 9. EXAMPLE 5 GENERATION AND CHARACTERIZATION OF ADDITIONAL ANTI-NKP46 VHH ANTIBODIES Additional anti-NKp46 VHH antibodies were identified and analyzed using the methods of Example 1 above. The sequences of the VHH CDRs of 35 of these antibodies are shown in Table 10. The full- length variable domains for these antibodies are shown in Table 11. Initial data for these antibodies is shown below: ELISA (Confirmatory): AR-765 (79337p2 n Atty. Dkt: OMNI-002WO CL-28044 1.449 0.175 0.059 0.046 CL-28043 2.916 2.461 1.134 0.232 n n n MATERIALS AND METHODS Atty. Dkt: OMNI-002WO Transgene design and development: The design and development of the truncated light chain (tLCi) was previously published (Leighton et al. J Immunol 2024; 212:1744–53). The OmnidAb transgene (called VHH3) was designed with a pre-rearranged V region consisting of a human VH3-23 and JH4, with an artificial CDR3 of 17 residues in length, consisting mainly of Gly and Ser residues (Figure 1). This germline-encoded CDR3 is expected to undergo somatic mutation in the chicken B cell to produce novel repertoires. The variable region frameworks (FRs) contain stabilizing mutations. The VHH3 transgene contains this single functional V region and non-coding sequences (V gene promoter, leader intron, and 5’ and 3’ untranslated regions) from the chicken heavy chain locus. Upstream of the single expressed VHH3 germline gene an array of designed pseudogenes (P-VHH) with diverse CDR sequences was cloned, for use in gene conversion to mutate the expressed functional V gene in B cells. CDRs 1 and 2 in the pseudogenes were derived from germline human VH3 family members, whereas CDR3s were sourced from expressed human repertoires and selected for a range of lengths and sequence diversity. These pseudogenes contain FRs that are identical to the functional VHH3 gene to preserve the embedded stabilizing mutations. In the case of FR4, sequences encoding the last 5 residues were omitted from the pseudogenes to remove potential primer binding sites from the genome. For insertion into the genome of chicken primordial germ cells and production of transgenic birds, a β-actin promoter and attB site were included on the vector for integration by phiC31 integrase into an attP site previously targeted to the chicken heavy chain locus. A loxP site was also included for removal of all selectable markers and plasmid backbone elements by Cre recombination36. Chicken primordial germ cells (PGCs) were derived and cultured as previously described, in KO-DMEM (ThermoFisher, 0829018) containing 40% buffalo rat liver (BRL)-conditioned medium, 7.5% fetal calf serum (FCS) (Hyclone, SH30088.03), 2.5% chicken serum (ThermoFisher, 16110082), 2 mM Glutamax (ThermoFisher, 35050-061), 1 mM pyruvate (ThermoFisher, 11360-070), 1X non- essential amino acids (ThermoFisher, 11140-050), 0.1 mM β-mercapto-ethanol (ThermoFisher, 21985- 023), 6 ng / ml recombinant murine stem cell factor (R&D Systems, 455-MC) and 4 ng / ml recombinant human FGF basic (R&D Systems, 234-FSE) on irradiated BRL feeder cells36. Cells were passaged every 2-3 days. PGC line VDJ10-9 was rederived from the germinal crescent of a transgenic bird carrying the IgH knockout and loxP sites flanking the VDJ region, and these cells were used for transfection. 5x106cells were resuspended in Nucleofector V buffer (Lonza, Walkersville, MD, VCA-1003) with 15 µg of linearized VHH3 insertion vector and 15 µg of a CMV-phiC31 integrase vector39in a total volume of 100 µl and transfected in a 2 mm cuvette using a BMX ECM830 square wave pulse electroporator (BTX, Holliston, MA) at 350V, 100 µsec, 8 pulses. Cells were resuspended in complete growth medium and transferred to a 48-well plate with G418-resistant irradiated BRL feeder cells36. G418 (Teknova, Atty. Dkt: OMNI-002WO Hollister, CA, G5005) was added at 350 μg / ml 3 days after transfection and the medium changed every 2-3 days. G418-resistant clones were expanded and confirmed to carry the correct VHH3 insertion into the heavy chain locus using PCR for the 5’ insertion (B-act-F2, 5’- CTCTGCTAACCATGTTCATGCCTTC-3’ (SEQ ID NO:2220) and neo-R1, 5’- AGTGACAACGTCGAGCACAGCT-3’ (SEQ ID NO:2221)) and 3’ insertion (huJH4-F2, 5’- TTTGACTACTGGGGCCAAGG-3’ (SEQ ID NO:2222) and chJC-R45, 5’- GCCCAAAATGGCCCCAAAAC-3’ (SEQ ID NO:2223)) and for the VHH3 gene using primers VHH3- F (5’-GTGAACGTCGGTCCAGGATT-3’ (SEQ ID NO:2224)) and VHH3-R (5- CTCGACCGTCAGCTGGTATC-3’ (SEQ ID NO:2225)) in a quantitative PCR (qPCR) assay. Three independent PGC clones and a pool of 3 other clones were injected into day 3.5 embryos to produce germline chimeras as previously described. Breeding male chimeras to Cre-expressing hens removed selectable markers and GFP and produced fully transgenic, VHH3 containing birds. Twenty of 25 chimeras transmitted through the germline with 6 chimeras transmitting >50%. Transgenic chicken evaluations Genotyping: Genotype confirmation was completed on either lysis of comb tissue (collected at hatch) or blood sample (collected at any older timepoint). Tissue lysis was completed in 0.5 mL ATL buffer containing 0.5% Proteinase K with incubation at 56ºC overnight with shaking. Ethanol precipitation of DNA was performed on lysed samples and used for downstream genotyping qPCR. For blood samples, lysis was completed with 0.25 μL whole blood in 1 mL of TEN buffer containing 0.005% pronase E with incubation at 37ºC overnight with shaking. Lysis reactions were inactivated by incubation at 65ºC for 10 minutes and sample used directly for genotyping qPCR. Birds were confirmed twice by genotyping qPCR before proceeding to bird evaluations. Sample collection and pre-processing: Birds were evaluated for B-cell development at 11 weeks of age, with n=1 chicken serving the wild-type reference control, n=3 from the IgL KO / VHH3 genotype, and n=6 from the tLCi / VHH3 transgenic genotype. These samples were used for analysis on flow cytometry, western blot, RT-PCR, and ELISA evaluations. For each bird, 2 mL whole blood in ethylenediaminetetraacetic acid anti-coagulant was collected for isolation of plasma or PBMC. An aliquot of 200 μL of whole blood was centrifuged at 600xg for 10 minutes at 4ºC to pellet down red blood cells and collect the plasma sample. Remaining whole blood was layered over 5 mL of Histopaque-1077 (Sigma-Aldrich, 10771) for PBMC isolation following the manufacturer’s protocol. The buffy coat containing the PBMCs was collected from the interface and washed once in PBS supplemented with 0.1% bovine serum albumin (BSA) (PBS+0.1% BSA), then aliquoted into 96-well U- Atty. Dkt: OMNI-002WO bottom plates for immediate downstream flow cytometry or pelleted and stored at -80ºC for RT-PCR processing. Flow cytometry: Plated PBMCs were incubated with primary antibodies diluted in PBS+0.1% BSA buffer for 1 hour on ice. Anti-chicken primary antibodies were used as follows: monoclonal mouse anti-Bu1 at 5 µg / mL for the chicken B-cell marker Bu1 (Southern Biotech, Birmingham, AL, 8395-01), monoclonal mouse anti-IgM at 5 µg / mL against IgM CH1 (Southern Biotech, 8310-01), monoclonal mouse anti-IgL at 5 µg / mL (Southern Biotech, 8340-01), monoclonal anti-TCR1 (TCRδγ) at 1:800 dilution (Southern Biotech, 8230-01), combined monoclonal anti-TCR2 (TCRαβ / Vβ1) and anti-TCR3 (TCRαβ / Vβ2) at 1:200 dilution (Southern Biotech, 8240-01 and 8250-01), and polyclonal goat anti-IgM at 4 µg / mL (Bethyl Laboratories, Montgomery, TX, A30-102A). Additionally, polyclonal serum against the VHH3 variable region domain included in the transgene design was produced via hyperimmunization of rabbits for transgene-specific antibody detection and used at 1:100 dilution. After primary antibody incubation, cells were washed 3 times in 200 μL / well PBS containing 1% BSA and 0.1% Na-azide (fluorescence-activated cell sorting (FACS) buffer) and then incubated with secondary antibodies conjugated with AlexaFluor647 for 1 hour on ice. The secondary antibodies used were: donkey anti- mouse at 5 μg / mL (ThermoFisher, A31571), donkey anti-goat at 4 μg / mL (Abcam, Waltham, MA, AB150131), or goat anti-rabbit at 4 μg / mL (ThermoFisher, A21244). After secondary incubation, cells were washed 3 times with PBS+0.1% BSA and read on an Attune NxT flow cytometer (Thermo Scientific) for analysis of 10,000 cells per sample. Produced data were processed in FlowJo software (version 10.8.1). Figures were produced in Prism software (version 9). ELISA: High-binding ELISA plates (Greiner Bio-One, 655061) were coated with 50 μL / well of either 2 μg / mL anti-chicken IgY (Sigma-Aldrich, C2288) or IgM (Sigma-Aldrich, SAB3700236), diluted in PBS. Plates were coated for 1 hour at room temperature or overnight at 4ºC. Plates were then blocked with 3% skim milk in PBS blocking buffer at 150 μL / well for 1 hour at room temperature. Plasma samples were diluted to 1:1,000 starting dilution with 5-fold serial dilution in the blocking buffer, then applied to the plate at 50 μL / well. Samples were incubated on the plate for 1 hour at room temperature. Plates were washed 5 times with 300 μL / well PBST wash buffer (PBS containing 0.05% Tween 20), then secondary was applied for 1 hour at room temperature. The goat anti-chicken IgM-horse radish peroxidase (HRP) (Bethyl, A30-120P) or rabbit anti-chicken IgY-HRP (Sigma, A90406) was diluted 1:5,000 in blocking buffer and applied to the plate at 50 μL / well. After incubation, the plate was washed 5 times in PBST. 3,3′,5,5′-Tetramethylbenzidine substrate (ThermoFisher, 002023) was applied at 50 μL / well and allowed to incubate for 10 minutes. Color development was stopped with 50 μL / well 1 N HCL and plates read for absorbance at 450nm in a BioTek Synergy H1 plate reader. Atty. Dkt: OMNI-002WO Western blot: Plasma samples were diluted to 1:100 in PBS, then prepared to contain a final concentration of 1X sample loading buffer and 1.5 mM tris-carboxyl-ethyl-phosphene reducing buffer and heated to 98ºC for 10 minutes. Samples were loaded into 4-12% bis-tris NuPage SDS-PAGE gels (ThermoFisher, NP0321) in 2-(N-morpholino)ethanesulfonic acid sodium dodecyl sulfate running buffer at a constant 200V. Gels were transferred to 0.2 uM nitrocellulose membranes using the iBlot27-minute dry transfer system (ThermoFisher). Membranes were immediately blocked in 3% skim milk in PBS blocking buffer for 1 hour at room temperature with shaking. After blocking, membranes were incubated with the primary antibody diluted in blocking buffer for 1 hour. Primary antibodies included polyclonal goat anti-chicken IgM diluted to 1:5,000 (Sigma, SAB3700236) or rabbit anti-VHH polyclonal serum at a dilution of 1:500. After primary incubation, membranes were washed 5 times at 5 minutes with oscillation with PBST buffer, then mouse anti-goat-HRP (Rockland, 18-8814-31) or goat anti-rabbit-HRP (Jackson ImmunoResearch, 111-035-144) secondary antibodies applied at either 1:10,000 or 1:5,000 dilutions, respectively, in blocking buffer for 30 minutes with shaking. After secondary incubation, membranes were washed as previously stated. West Pico PLUS chemiluminescent substrate (ThermoFisher, 34580) was applied for 15 minutes of development, then membranes were imaged on a BioRad ChemiDoc XRS+ gel imager under the chemiluminescence filter. Reverse transcription PCR: Total RNA was extracted from the pelleted PBMC samples using the RNAeasy Plus kit (Qiagen 74034) using 107cells per sample for extraction and following the manufacturer’s protocol. Extracted RNA was resuspended in 30 μL water and quantified using the Nano UV-Vis spectrometer. Quantifications obtained were used for normalization of samples. Then 2 μL of RNA was used in a reverse transcription / amplification reaction using the Qiagen One-Step RT-PCR kit (Qiagen 210212). Primers used in these reactions targeted IgM (chVH-F9: 5’- CACCAGTCGGCTCCGCAACCATG-3' (SEQ ID NO:2226) and cIgM-CH2-R5: 5’- GGGATGGGAATCGGGGGACC-3’ (SEQ ID NO:2227)) or IgL (cVL-5'UTR-F: 5’- GACACACAGCTGCTGGGATTC-3' (SEQ ID NO:2228) and chIgL-C-R: 5’- CCTGCAGGTGTAGGTCTCGT-3' (SEQ ID NO:2229)). RT-PCR parameters consisted of a 30-minute reverse-transcription at 50ºC, followed by 40 cycles of: 30 seconds of denaturation at 94ºC, 1 minute of annealing at 60ºC, and 45 seconds of extension at 72ºC, with a final extension of 10 minutes. RT-PCR products were loaded and run on 1% agarose-ethidium bromide tris acetate ethylenediaminetetraacetic acid gels and imaged with a BioRad ChemiDoc XRS+ gel imager. Antibody Discovery Immunizations and sample collection: OmnidAb transgenic chickens were selected for immunization after confirmation of B-cell development in PBMC by flow cytometry and plasma Atty. Dkt: OMNI-002WO immunoglobulin titer by ELISA (as mentioned above). Birds were immunized with either soluble NKp46 extracellular domain protein (produced in-house) or soluble human progranulin protein (Acro Biosystems PGN-H52H3) at 100 μg of protein per dose per bird via intramuscular administration. Primary immunization contained 1:1 v / v Complete Freund’s Adjuvant (Thermo Fisher, 77140), while boosts contained 1:1 v / v Incomplete Freund’s Adjuvant (Thermo Fisher, 77145). Immunization schedule followed an every-other-week pattern of immunization one week with sample blood draw the following week. Upon hyperimmunization and achievement of high titer response (based on ELISA, procedure described below), a final non-adjuvated boost was administered intravenously. Final plasma sample collection and splenocyte harvest was completed 4 days after the final intravenous boost. Spleen outer membranes were removed and parenchyma tissue processed using 40 μM cell strainers into PBS+0.1 BSA buffer. Single-cell splenocyte samples were then layered over Histopaque-1077 (Sigma-Aldrich, 10771) polysucrose gradients to collect buffy coats containing lymphocytes and mononuclear cells from the total splenocyte samples. Collected cells were cryopreserved in medium containing 10% FCS and 10% dimethyl sulfoxide, and aliquots were stored in liquid nitrogen until used for screening. Single B-cell screening and cloning: Single B-cell screening was completed on cryopreserved cells using either the GEM assay method41(US Patents: 8,030,095 and 8,415,173) or the xPloration method42(US Patents: 10,227,583; 11,085,039; 11,473,081; and 12,024,705). For the GEM method, 5 μM latex-aldehyde beads (Thermo Fisher, A37306) were coated with 37.6 μg soluble protein per 100 μL of bead solution in PBS buffer overnight at 4ºC on a rotator. After overnight coating, beads were washed and blocked with 3% skim milk in PBS for 1 hour, followed by 5 washes with PBS, then finally brought back to original bead volume. Coated beads were stored at 4ºC until use in gel encapsulated microenvironment (GEM) screening. The GEM method facilitates single B-cell screening by encapsulating single B cells with the antigen-coated beads into agarose gel micro-droplets. B cells secreting antibodies specific to the antigen are detected by a fluorophore-labeled secondary antibody and manually screened / extracted under the microscope. GEMs containing the B cells and antigen-coated beads were prepared, incubated for 3 hours at 37ºC in RPMI media supplemented with 10% FCS and Glutamax, pre-mixed with 2 μL / mL goat anti-chicken IgM-DyLight 594 secondary antibody (Novus Biologicals, NBP2-60690DL594). GEMs were washed 3 times in CO2-Independent Media containing 10% FCS and Glutamax media before viewing under the microscope. GEMs containing single B cells and positive staining on beads were extracted for cloning. For the xPloration screening method, the antigen target protein is coated onto M450 Dynabeads (Thermo Scientific, 14044) following manufacturer coating procedures. Cells were washed in PBS supplemented with 0.1% BSA and mixed with coated beads at a ratio of 4800 cells per 1 μL of coated beads in RPMI base media containing 4-(2- Atty. Dkt: OMNI-002WO hydroxyethyl)-1-piperazineethanesulfonic acid and glutamine supplemented with 10% FCS, pre-mixed with goat anti-chicken IgM-DyLight 650 secondary antibody (Novus Biologicals, NBP2-60690DL650) at 1:1000 dilution. The cell-bead-secondary mix was spread onto a microcapillary chip containing 1.5 million capillaries, a 1% agarose overlay was applied, and the entire chip was incubated for 2 hours at 37ºC. After incubation, the chip was loaded into the xPloration instrument and screened for binding to the antigen-coated beads for each capillary well. Contents of individual positive wells were laser- extracted from the chip for cloning. After extraction of antigen-specific single B cells (either by GEM or xPloration), cells were lysed using TurboCapture mRNA kits (Qiagen, 72251) following manufacturer instructions for single-cell mRNA preparations. Reverse transcription PCR was performed on the samples to amplify the entire heavy variable region using primers in the 5’ UTR: 5’- ACACTCTTTCCCTACACGACGCTCTTCCGATCTCACCAGTCGGCTCCGCAACCATG (SEQ ID NO:2230) and IgM CH2 exon: 5’- GACTGGAGTTCAGACGTGTGCTCTTCCGATCTGGGGTGCATGGTG ACGAAAAG-3’ (SEQ ID NO:2231) regions. This was followed by a nested PCR using primers with overhangs in the VH-leader: 5’-TCGAACCCTTGCTAGCCGCCATGGAGTTTGGGCTTAGCTGGATC (SEQ ID NO:2232) and JH-region: 5’-TGAGGAGACGGTGACCTGGGT (SEQ ID NO:2233). These amplified VH regions were then inserted into a mammalian expression vector containing an IgG1 CH2-CH3 human Fc domain using the In-Fusion method (Takada Bio, 638911), creating a sdAb-Fc format, also referred to as HcAb. Clones were transfected into Expi293 cells for protein expression and used for downstream analysis. Control antibodies to PGRN representing in-house clones from wild-type chicken21and transgenic OmniChicken®and OmniClic™animals27-29and to NKp46 (NKp46-1, NKp46-2, NKp46-3, and NKp46- 4; US patent application US20240034816 and PDB ID 6IAP) from OmniClic and OmniFlic were generated as scFv-Fc (PGRN) or full IgG (NKp46) constructs with a human IgG1-Fc and purified by standard protein A chromatography, as described for the OmnidAb antibodies. Antigen-specific ELISAs: ELISA for antigen-specific binding followed the same standard procedures as previously mentioned, but with these stated modifications. Plates were coated with the target antigen at 2 μg / mL. Detection of antigen-specific binding antibodies utilized either the goat anti- chicken IgM-HRP (Bethyl, A30-120P) for screening during the immunization stage or rabbit anti- human-Fc-HRP (Rockland, 609-4303) during the monoclonal screening phase. During screening for immunoresponse to antigen during the immunization stage, plasma samples were applied at a starting dilution of 1 / 100 in blocking buffer (for PGRN immunizations) or 1 / 500 (for NKp46 immunizations), followed by 7-rounds of a 5-fold serial dilution. During the monoclonal screening phase, transfected Expi293 supernatant was initially screened for antigen-binding using a sample dilution of 1 / 50. After Atty. Dkt: OMNI-002WO initial qualitative screening, these clones were sequenced to sort out clones with unique sequences. Representative clones for each unique sequence group were then selected for normalized ELISA analysis and downstream flow cytometry, kinetics, epitope binning, and functional assays. Normalized ELISA for unique sequence clone representatives were applied at a starting dilution of 1 μg / mL, followed by 3- rounds of 5-fold serial dilutions to observe dose-response binding curves. Selected unique sequence clones which maintained strong binding were selected to move forward for further evaluation. Antigen-specific flow cytometry for NKp46 clones: A randomly selected subset of NKp46- binding HcAbs was screened for the ability to bind to native NKp46 protein on transfected CHO-K1 cells (KYinno Bio, KC-1789). The CHO-K1 cells (parental and NKp46-expressing) were cultured in Ham’s F12K media (Gibco, 21127022) supplemented with 10% FBS. The NKp46-expressing CHO-K1 cells were grown with 10 μg / mL puromycin selection. On the day of flow cytometry, cells were removed from the adherent surface with cell dissociation buffer (Corning, 25-066-CI) for 10 minutes at 37ºC, washed with FACS buffer (400xg for 10 minutes at 4ºC), and counted using a hemocytometer. For each cell type, washed cells were resuspended in 250 μL human Fc block (BD, 564220) and incubated at room temperature for 10 minutes, protected from light. Cells were plated at 1.5x105cells / well at 200 μL / well in FACS buffer and pelleted before applying primary antibodies. NKp46- binding antibodies were applied to the well at a starting dilution of 10 μg / mL, with three 5-fold serial dilutions, at 50 μL / well and incubated for 45 minutes on ice. A NK-binding mouse anti-CD335 monoclonal positive control antibody was also included in the assay (Invitrogen, 16-3359-82) at the same working concentrations. After primary incubation, the cell plate was washed twice with FACS buffer and the secondary applied at 50 μL / well for 45 minutes on ice, protected from light. The secondary antibodies used were: goat anti-human IgG-AlexaFluor 647 (Thermo, A21445) or goat anti- mouse IgG-AlexaFluor 647 (Thermo, A21235) at 1:500 dilutions. After secondary incubation, cell plates were washed twice and resuspended in 200 μL of FACS buffer before processing for analysis on the Attune NxT flow cytometer (Thermo Scientific). IFNγ release assay: CD56 / CD16-positive human primary NK cells (Lonza, 2W-502) were cultured in ImmunoCult NK Cell Expansion media (Stemcell Technologies, 100-0711) for 10-14 days according to manufacturer’s recommended protocols at 37ºC with 5% CO2. On the day of testing, cells were harvested and seeded into sterile 96-well microplates at a density of 150,000 cells / well in 50 μL of culture media. A randomly selected subset of NKp46-binding clones (same clones as above) was tested at 30 nM and controls applied at 100 nM, 30 nM, 10 nM, 3 nM, 1 nM, 0.3 nM, and 0.1 nM. Reference antibodies from the patent literature were included (NKp46-1, NKp46-2, and NKp46-3; US20240034816). Ionomycin (Sigma-Aldrich, I0634) was used as an assay positive control and applied Atty. Dkt: OMNI-002WO at a final concentration of 1 μM. A human IgG antibody isotype control (ThermoFisher, 02-7102) was also included and applied at final concentration of 30 nM (matching the concentration used for experimental samples). Samples were run in 4 replicates over 2 separate assay runs, totaling 8 replicates per sample. Treatments were prepared at 2X the final testing concentration in media, with 50 μL of each 2X concentration sample applied to the wells containing the 50μL of cells (1:1 v / v) for 24 hours treatment incubation. After incubation, plates were briefly centrifuged at 500xg for 10 minutes and 50 μL of supernatant collected to a fresh 96-well microplate for ELISA processing. IFΝγ concentrations of samples were determined using a commercially available human IFNγ ELISA kit (Abcam, AB300323), following the manufacturer’s protocol and included standard curve controls. Sample supernatants were diluted to 1:20 for the ELISA. Results were measured on a BMG Clariostar plate reader and absorbance values were converted to concentration using the IFNγ standard curve calculated from the linear fit regression equation. Statistical significance calculated in comparison to the media-only control. Evaluation and developability of antigen-specific antibody clones Sequence analysis: AA sequence diversity of antigen-specific HcAbs was completed by multiple sequence alignment of the heavy-chain variable regions and germline sequences using the IMGT numbering system to identify the CDR regions (CDR1: 27-38, CDR2: 56-65, and CDR3: 105- 117). At each position, the occurrence of all non-germline amino acids was calculated and plotted using Logomaker, dmslogo, funcgroup, and ANARCI45. Pseudogene usage identification of antigen-specific clones was completed by first locating regions of gene conversion on the DNA sequence. Queried CDR sequences with 4 bp or more identity match to germline pseudogene sequence were considered a result of gene conversion. Sequence fragments were required to be 100% match to the germline pseudogene sequence to be considered. Sequences 3 bp or less were considered too short to definitively confirm gene conversion and may be a result of somatic hypermutation. Some germline pseudogenes had matching stretches of sequences, at which point the specific pseudogene origin for that gene conversion event could not be determined and was considered an undefined gene conversion with multiple potential pseudogene sources. Analysis of gene conversion usage and pseudogene origin was completed with the SequenceMatcher tool from Biopython. The phylogenic tree was generated by first aligning sequences using Clustal Omega (ClustalO), calculating pairwise distances based on the sequence identity of the entire variable heavy chain region, and constructing the tree with the UPGMA algorithm from Biopython Phylo TreeConstruction package. The tree was visualized in a circular style, with the clones on the leaves of the tree colored to match the bin color used in the binning experiments. Sequence lineages were defined as a group of antibody sequences with up to 2 AA edit distance in the concatenated CDR1 and CDR2 regions and up to 2 AA edit distance in the CDR3 region. The lineage identifications (ID) Atty. Dkt: OMNI-002WO were ranked, with the lineage containing the largest number of unique sequences ranked at the top as Lineage ID 1. Immunogenicity Analysis: To examine the potential for immunogenicity, an in silico evaluation was performed on a subset of antigen-specific OmnidAb antibodies selected to encompass a diversity of sequences to four different targets. The antibody sequences were analyzed as overlapping 9-mer segments and screened with EpiVax software for the presence of Class II (HLA-DR) restricted human leukocyte antigen (HLA) ligands and putative T-cell epitopes47-48. The software calculates binding potential to the most common HLA molecules within HLA “supertypes”. The total number of putative T-cell epitopes is used to generate an EpiMatrix score which is further adjusted for T-regulatory (Tregitope) binding sites. Binding to T-regulatory cells may reduce immunogenicity, and thus offset the raw EpiMatrix score. Tregitope-adjusted EpiMatrix scores <-15 are considered to have low immunogenicity and scores <-30 are considered to have minimal immunogenicity. Putative T-cell epitopes identified in the EpiVax screen were further characterized with the JanusMatrix software49. Activation of T-cells requires peptides to bind HLA binding clefts on antigen presenting cells and present the MHC:peptide complex to T-cell receptors (TCR). The simultaneous binding results in two ‘faces’: TCR-facing AA residues and major histocompatibility complex (MHC)-facing AA residues. TCR-facing residues that are highly conserved within the human proteome are less likely to generate an immune response whereas novel sequences may be recognized as foreign and activate T-cell responses. The JanusMatrix algorithm matches the predicted T-cell epitopes to human proteins. A high JanusMatrix Human Homology Score (>5) suggests a reduced immunogenic potential50. Antibody Purification: HcAbs were high-throughput purified from Expi293 supernatant using a Hamilton Nimbus equipped with PhyTip Protein A Columns (Biotage, PTH-91-40-07). Columns were equilibrated in PBS pH7.4 before capturing sdAb-Fc antibodies. The columns were subsequently washed twice in PBS pH7.4. Samples were eluted off the column in 50 mM sodium citrate pH3.0, 150 mM sodium chloride, and immediately neutralized by addition of 0.5 M sodium phosphate pH9. Neutralized solutions were buffer exchanged into PBS pH7.4 in high throughput 96-well desalting plates (ThermoFisher, #89807). Thermal stability and aggregation: Differential scanning fluorimetry (UNCLE-0330, Unchained Labs, Pleasanton, CA) was used for assessment of the melting temperature (Tm) and aggregation temperature (Tagg) on selected NKp46 and PGRN antibody clones in sdAb-Fc format. The samples, which are in PBS pH7.4, were loaded onto the microcuvette arrays at low injection volume (9 μL) and in a broad concentration range from 0.05–5 mg / ml. A temperature ramp from 20ºC to 95ºC was applied with a 1.0ºC / min increment, incubation time of 180 seconds, and a plate hold of 60 seconds. Change in Atty. Dkt: OMNI-002WO 350 / 330-nm absorbance ratio was used to analyze Tm and Tagg. Intrinsic protein fluorescence (excitation: 266 nm, emission: 280-450nm) was monitored for measurement of Tm. The aggregation curve was generated through measurement of temperature-dependent intensity of static light scattering (excitation: 266 nm). Static light scattering at 473 nm was monitored for measurement of Tagg. All data were analyzed directly with UNcle Analysis Software (V.6.0). and Tm and Tagg were determined using 350 / 330 nm absorbance ratio or SLS473 (counts.nm) vs. temperature (ºC) plots, respectively. AC-SINS: Both polyclonal goat anti-human IgG Fc (Jackson ImmunoResearch, #109-005-098) (capture) and whole goat IgG (Jackson ImmunoResearch, #005-000-003) (non-capture) antibodies were buffer exchanged into 20 mM potassium acetate (pH 4.3) buffer and normalized to 0.4 mg / mL. The two antibodies were mixed at a ratio of 4:1 of capture:non-capture. Antibodies were incubated with gold nanoparticles (Ted Pella Inc. #15705) at a ratio of 9:1 of gold nanoparticle to antibody for 2 hours at room temperature. Empty sites were then blocked by addition of 0.1 μM (final conc.) poly-ethylene glycol methyl ether thiol (2000 MW, Sigma-Aldrich #729140). The coated and blocked particles were passed through a 0.22 μm polyvinylidene fluoride membrane (Millipore Sigma #SLGVV255F) and eluted with 10% starting volume of PBS. To assess self-association, 10 μL nanoparticles were mixed with 100 μL purified antibody at 50 μg / mL in PBS, pH7.4 in a 96-well polypropylene plate. As a control, buffer was mixed with coated and blocked gold nanoparticles. Absorbance was measured on a BioTek Synergy H1 plate reader from 510 to 570 nm in increments of 1 nm. The peak absorbance wavelength was calculated manually using Excel. Control buffer peak absorbance wavelength was subtracted from the sample peak absorbance wavelength, and these data were plotted. Analytical SEC: Analytical SEC-HPLC was performed for OmnidAb samples using a Superdex 200 Increase 5 / 150 GL column (Cytiva, GE28-9909-45) on an UltiMate 3000 HPLC (Thermo Scientific). Concentration of antibodies ranged from 0.2-1 mg / mL with a couple outliers below 0.1 mg / mL and above 1.5 mg / mL. The buffer formulation for both the sample and running buffer was PBS pH7.4 with a flow rate of 0.25 mL / min at room temperature over 15 minutes. Biosensor analysis: Binding kinetics, epitope mapping, and epitope binning experiments were performed by high-throughput surface plasmon resonance on Carterra’s LSA platform equipped with HC-30 M sensor chips. The method has been previously described in detail elsewhere. To calculate binding affinity, a capture kinetic method was used on a chip coupled with goat anti-human IgG Fc- specific polyclonal (Southern Biotech, 2047–01) capture reagent. Purified recombinant His-tagged PGRN (R&D systems) and NKp46 (prepared in-house) were used as monovalent analytes and prepared as a 3-fold dilution series with top concentrations of 300 nM or 1 μM. Epitope mapping of anti-PGRN HcAbs to specific granulin subdomains was accomplished using a chimeric swap strategy as described Atty. Dkt: OMNI-002WO previously. Epitope binning experiments were performed using a classical sandwich method as described previously merged with a curated panel of antibody standards to guide bin assignments. For PGRN binning, the standards represented a panel of previously characterized clones of known specificities whereas for NKp46 binning, the standards represented so called ‘anchor’ clones from in- house unpublished OmniFlic and OmniClic repertoires generated by standard protein-based immunizations, and literature benchmarks (NKp46-1, NKp46-2, NKp46-3, and NKp46-4; see “single B- cell screening and cloning section” above). Anti-His mAb was used as a universal sandwiching control for all epitope binning experiments. For NKp46 binning, a ‘many-on-few’ approach was used where a large panel of HcAb analytes (in solution) was tested for blocking against a small, curated panel of ligands (on chip) comprising anchor clones and a limited set of HcAbs that tolerated multiple cycles of acid-regeneration. Since a comprehensive pairwise analysis was not performed for NKp46 HcAbs, they were not tested for mutual competition against one another, so were assigned to ‘blocking profiles’ (herein referred to as ‘bins’). In this definition, HcAbs belonging to the same blocking profile do not necessarily block one another but show the same blocking pattern when tested against the ligand set. EXAMPLE 6 PRODUCTION OFOMNIDAB TRANSGENIC CHICKENSTo express a heavy chain variable region without a light chain in a transgenic animal, two challenges associated with removal of the light chain need to be addressed: exposure of the VH / VL interface on the VH region and lack of a pairing partner for the CH1 domain of the heavy chain constant region that is normally paired with the CL. A heavy chain variable region based on human VH3-23 and JH4 germline sequences was designed, with 10 stabilizing mutations that enable its expression as an autonomous VH (FIG.8). These stabilizing mutations are found in camelid VHH and serve to stabilize the overall structure of the single unpaired domain by reshaping the former contact regions with VL and CH1 and increasing hydrophilicity of positions that become solvent-exposed when VL and CH1 are removed25. This variable region was inserted into the chicken heavy chain locus in which the endogenous V, D, and J gene segments had been deleted (FIG.1). The construct contains the regulatory elements of the chicken IgH locus for proper temporal and tissue-specific expression. In wild-type chickens, single VH and JH genes and a small number of highly related D genes are utilized in VDJ recombination26. Because VDJ recombination provides minimal diversity to the antibody repertoire in chickens, a pre-rearranged VH region for OmnidAb antibodies was used, bypassing the recombination step. This germline variable region and the transgene that carries it is referred to as “VHH3”. Repertoire diversity in chicken immunoglobulins is normally generated by gene conversion from upstream Atty. Dkt: OMNI-002WO pseudogenes; this process was replicated by the inclusion of an array of designed human-based pseudogenes that are available in developing B cells for gene conversion of the single, expressed VHH3 gene (FIG.8). The stabilizing mutations are present in the FRs of the pseudogenes, serving to maintain their presence in the somatic repertoire. Any random mutations in the FRs would be reverted to the original sequence by gene conversion. In contrast, the complementarity-determining regions (CDRs) contain diverse sequences for production of a diverse repertoire of antibody sequences. As for the CH1 domain in the constant region, which normally requires pairing with the light chain to displace BiP and enable proceeding through the secretory pathway, a second transgene was engineered in the light chain: a truncated light chain (tLCi) consisting of only the constant region without a variable region. This transgene was inserted into the light chain locus, in which the endogenous V, J, and C regions had been deleted. These transgenes were inserted into primordial germ cells, chimeras were produced, and the chimeras bred to establish fully transgenic lines. Birds with both the VHH3 and tLCi transgenes were produced, in addition to VHH3 birds with a homozygous IgL knock out (KO). At the heavy chain locus, the genotype was heterozygous VHH3 / IgH KO and at the light chain locus, either: heterozygous tLCi / IgL KO or homozygous IgL KO / IgL KO. To simplify references to these transgenic genotypes, these genotypes will be referred to here as VHH3-tLCi (for tLCi / IgL KO light chain alleles with VHH3 / IgH KO heavy chain) or VHH3-IgL KO (for homozygous IgL KO / IgL KO light chain alleles with VHH3 / IgH KO heavy chain). EXAMPLE 7 B-CELL DEVELOPMENT AND ANTIBODY EXPRESSION IN OMNIDAB CHICKENS Analysis of B-cell development in these heavy chain-only chickens showed similar titers of circulating IgM, but very limited isotype switching to IgY (FIG.2A), based on enzyme-linked immunosorbent assay (ELISA), correlating with the limited isotype switching observed in the previously developed heavy chain-only chicken expressing wild-type chicken HcAbs24. Flow cytometric analysis (FIG.2B) of the VHH3-tLCi transgenic chicken peripheral blood mononuclear cells (PBMCs) exhibited proper development of B cells, based on Bu-1 staining, with the B-cell population averaging about 30- 60% of normal (3% of total PBMC compared to 5-10% in wild-type chickens). Polyclonal staining for surface IgM also confirmed expression of antibodies on these B cells, but monoclonal IgM staining specific to the CH1 domain did not detect a positive population in the VHH3-tLCi or VHH3-IgL KO transgenic genotypes. Monoclonal IgL staining was also negative for both transgenic genotypes, consistent with the lack of a CH1 domain for CL binding, but remained positive for the wild-type Atty. Dkt: OMNI-002WO control. Additionally, polyclonal rabbit serum raised against the transgenic VHH3 domain was produced to serve as an additional VHH3 transgene-specific detection method during analysis of B-cell development. In flow cytometry, this anti-VHH3 antibody only detected cells in the transgenic birds and did not stain any cells in the wild-type chickens. Sample control staining to the T-cell receptors (TCRs) was comparable between the wild-type control and the transgenic birds. Reverse transcription (RT)-PCR of the PBMC samples for detection of IgL or IgM messenger RNA (mRNA) was also performed (FIG. 2C). For IgL transcription, the VHH3-IgL KO genotype contained no light chain, as expected, while the VHH3-tLCi genotype contained the truncated light chain, smaller than the full-sized light chain exhibited in the wild-type chicken. For IgM transcription, both transgenic genotypes contained heavy chains that were ~300 base pair (bp) smaller than the wild-type heavy chain, consistent with CH1 deletion in the heavy chain. Western blots of the plasma samples for detection of IgM antibody (FIG.2D) are consistent with the flow cytometry and RT-PCR data (FIGS.2B and 2C), in that the heavy chain protein exhibited smaller bands compared to the wild-type, confirming the OmnidAb transgenic chickens, both the VHH3-IgL KO and VHH3-tLCi versions of the genotypes, do not express the CH1 domain. EXAMPLE 8 ANTIBODY DISCOVERY INOMNIDAB TRANSGENIC CHICKENSOmnidAb transgenic chickens were immunized with either human progranulin (PGRN) protein or the extracellular domain of the human natural killer (NK) cell receptor, NKp46. PGRN is a multi- domain protein that has served as an antigen target for multiple transgenic chicken evaluations, with well-established reference controls for each of the granulin domains in epitope binning21. NKp46 was also chosen as a target because of the potential for the development of bispecific, NK-cell engager antibodies as therapeutics. Strong antigen-specific plasma titers were observed in these birds, with no background binding to non-specific protein detected (FIG.2E). Upon reaching sufficient titer, splenocytes were collected and screened for secretion of antigen-specific antibodies using GEM and xPloration technologies. GEM and xPloration are both single B-cell screening technologies, the former utilizing agarose gel microenvironments for screening on a microscope with manual removal of selected cells and the latter utilizing a microcapillary chip with laser extraction of selected wells. Following single B-cell screening for antigen-specific binding, variable regions were amplified and cloned into an expression vector carrying a human Fc. Recombinant sdAb-Fc antibody was the format tested in all downstream assays. A total of 38 anti-PGRN clones and 128 anti-NKp46 clones were identified and confirmed in ELISA. Binding was specific as no binding to an unrelated protein or His-tag was observed. Atty. Dkt: OMNI-002WO A randomly selected subset of 12 antibodies was screened for their ability to bind native NKp46 protein expressed on the surface of Chinese hamster ovary (CHO) cells by flow cytometry (FIG.2F) and all exhibited binding to the NKp46-expressing cells with little to no background binding to the parental CHO cells. Thus, binding to the immobilized protein on ELISA (data not shown) correlated well with binding to native protein for the NKp46 target. Most of this subset was also tested for the ability to activate primary human NK cells to release interferon gamma (IFNγ) in cell culture. Of the 11 clones tested, two clones were able to significantly induce the release of IFNγ, as compared to the media-only negative control, and were comparable to the positive reference control antibody included in the assay (FIG.2G). As expected in antibody discovery, not all of the antigen-binding antibodies, in this case NKp46, have the ability to activate the target receptor, but functional activity can be easily included in the pipeline during antibody discovery should this be a desired characteristic for the antibody. Sequence analysis of the anti-PGRN and anti-NKp46 OmnidAb clones showed that FRs 1, 3, and 4 were largely unchanged, with the stabilizing mutations still present in most of the clones (anti-NKp46 data shown in FIG.3A). This was expected since the VHH3 pseudogenes contained FR sequences identical to those in the functional gene, so gene conversion in the FRs would serve to maintain the original sequence rather than mutate it. The one exception was FR2, in which substantial levels of mutation were observed, even though the pseudogenes contained identical sequences. These mutations must have occurred through random somatic hypermutation (SHM) and were not reverted or erased by gene conversion (GC). These changes were mainly in the hallmark FR2 stabilizing residues that are defined as framework by the international ImMunoGeneTics information system (IMGT), but the other residues also affected are considered CDR1 or 2 in the Kabat definition, suggesting that they could be antigen-contact residues. One of the stabilizing changes is in Vernier residue W52 (IMGT) and shows diverse mutations, suggesting it may affect the CDR structure in those clones. In a few clones, W118 (the first residue of FR4) was mutated to arginine, as is observed in some camelid VHHs. These FR2 and FR4 changes are likely undergoing positive selection, considering the other FRs did not show similar levels of mutation. The overall hydrophobicity of FR2 as measured by GRAVY remained in the hydrophilic range, with some clones having a higher score (tending toward hydrophobic) than the germline and others lower (more hydrophilic) (FIG.9). Thus, the mutations in FR2 were not the result of a consistent selection for increased hydrophilicity, although selection for other biophysical attributes such as stability could be occurring. The CDRs also showed high levels of variation in the set of clones. The CDR3 lengths for the set of PGRN and NKp46 clones were centered around a length of 17, which is the length in the germline VHH3 gene (FIGS 10A and 10B). However, for both targets, some shorter or longer CDR3s were observed, indicating that gene conversion and / or SHM can lead to insertions or Atty. Dkt: OMNI-002WO deletions in the repertoire in birds. For the PGRN clones, a prominent lineage with a CDR3 length of only nine residues was apparent. Gene conversion by the designed pseudogenes was analyzed for the set of PGRN and NKp46 clones using an algorithm that detects stretches of sequence that can be traced to a pseudogene. Gene conversion was detected in most of the sequences (Table 1), whereas some clones contained mutations such as point mutations or stretches shorter than four base pairs that could not be assigned to gene conversion with the algorithm. Most of the gene conversion events could be assigned to a specific pseudogene, while some of them were ambiguous and had sequence matches in more than one pseudogene. Table 13. Gene conversion frequencies. CDR # Tota # CDR Target l # CDR w / GC # CDR # CDR w / GC CDR not found w / GC defined w / GC d ana lyzed for evidence of gene conversion (GC) by the upstream designed pseudogenes in the VHH3 construct. For most of the CDRs, gene conversion could be assigned, with only a few sequences showing mutations that could not be traced to a pseudogene (GC not found). None of the CDRs showed the germline VHH3 sequence. For the GC events, most were traced to a specific pseudogene (GC defined) whereas in some cases, it was ambiguous as more than one pseudogene could have donated the sequence (GC undefined). All pseudogenes were found to participate in gene conversion and contribute sequence diversity to the clones (FIG.3B). Mapping of the gene conversion events showed that up to 6 events within a CDR could be involved in mutating the sequence (FIG.4). CDRs showed a range in terms of number of gene conversion events and lengths of sequence donated by pseudogenes in each case. OmnidAb antibody sequences were evaluated in silico for potential immunogenicity and were compared with benchmark controls as well as clinical-stage VHH molecules. Tregitope-Adjusted EpiMatrix Scores were calculated and plotted relative to JanusMatrix Human Homology Score (FIG.5). Atty. Dkt: OMNI-002WO The plot can be divided into quadrants based upon high / low T-cell epitope density (EpiMatrix score) and high / low human homology (JanusMatrix score). The sequences with the lowest immunogenic potential have low T-cell epitope density and the putative epitopes that are present have high homology with the human proteome. Conversely, high T-cell epitope density and low homology with human proteins predicts a high risk of immunogenic response. All OmnidAb sequences had a high JanusMatrix human homology score. Tregitope-adjusted EpiMatrix scores were variable, but primarily fell into the low to minimal risk categories. Consequently, the majority of the sequences analyzed fell within the lowest risk quadrant and no OmnidAb sequences were observed in the highest risk quadrant. A small number of the sequences had higher (>-15) EpiMatrix scores, but this may be partially offset by high human homology. The immunogenic potential of OmnidAb sequences was comparable to other clinical-stage VHH molecules. EXAMPLE 9 OMNIDAB ANTIBODIES SHOW BROAD EPITOPE COVERAGETo assess the epitope coverage of antibodies produced from the immunization of OmnidAb engineered animals, a detailed epitope binning studies on panels of OmnidAb clones was performed. Epitope binning studies served to corroborate and expand upon the results determined by our chimeric- swap epitope mapping strategy, which was restricted (by design) to only human-specific, and not mouse cross reactive, clones. Despite the small sample size of only 38 OmnidAb antibodies, their epitope coverage not only overlapped with, but extended beyond, that of our standards, which represented a curated set of clones from previous PGRN campaigns in wild-type (Abdiche et al, mAbs 2016; 8:264– 77), OmniChicken (Ching et al, PLoS One 2020; 15:e0228164 and Ching et al, mAbs 2018; 10:71–80), and OmniClic (Ching et al mAbs 2021; 13) chickens. A total of 11 blocking profiles or ‘bins’ were identified, covering all 7 granulin subdomains (A, B, C, D, E, F, and G) including the small N-terminal paragranulin (p). Some newly identified epitopes not represented by our standards included a CD epitope that bridged two non-overlapping epitopes represented by our standards (CD + CD’), an E bin epitope that did not block our E bin standard (E’), an E bin epitope that bridged E+E’, a new G bin (G’), and a B epitope that blocked our B standards, but showed no binding to any of the chimeras, thereby deviating from the mapping result characteristic of B bin clones (chimera-2 binders). The most populated bins were p and F with 16 and 7 members each, with other bins each being populated by one to three clones. Epitope bin assignments correlated with antibody sequence for anti-PGRN antibodies. As expected, clones with highly similar sequences targeted the same bin, but it was also observed cases Atty. Dkt: OMNI-002WO of dissimilar clonal lineages converging on the same bin, as shown for p and F binders, which were each represented by three distinct clonal lineages. The epitope coverage produced for a panel of 102 unique-sequence anti-NKp46 antibodies was also analyzed. Bin assignments were deduced from a merged analysis of three heat maps generated from a series of epitope binning experiments that used an intersecting but non-identical set of clones. A total of 12 blocking profiles were identified, representing five non-overlapping bins (1, 2, 3, 4, and 5) with nuanced blocking behaviors fracturing bin 1 through bin 4 into sub-bins; 1b / c / d, 2a / b / c, 3a / b, and 4a / b / c. In comparison, the four literature benchmarks used (NKp46-1, NKp46-2, NKp46-3, and NKp46-4) were assigned to bins 1a, 2c, 3b, and 1e, respectively. Therefore, the OmnidAb antibodies not only closely recapitulated the blocking profiles of all the benchmarks used, but showed expanded epitope coverage that produced new and distinct epitopes, bin 4 (comprising 4a / b / c sub-bins) and bin 5. Anti-NKp46 clones clustered by their antibody sequences. As observed for our PGRN example, clones with highly similar sequences targeted the same bin, while, for some bins, multiple disparate clonal lineages converged on the same bin. Fine epitope differences, as defined by sub-bins, were also highly correlated with antibody sequences, showing the exquisite discriminatory power of our binning method. The he affinities of the antibodies produced against both model targets were also determined and it was found that they exhibited a range of kinetic profiles, with some of the highest affinity clones attaining single digit nM KD values (FIGS.6A and 6B). Full kinetics and bin assignments for the NKp46 antibodies are provided in Table 14 below. Clone ID ka (M-1s-1) kd (s-1) KD(nM) Bin Lineage_id M2-C06 770E+04 361E-02 469 1b 22 Atty. Dkt: OMNI-002WO M17-A01 5.37E+04 2.77E-02 517 4a 1 M17-A10 1.39E+05 1.02E-02 73 4a 1 Atty. Dkt: OMNI-002WO M12-D05 5.46E+04 9.58E-03 175 4c 2 M12-E03 7.52E+03 3.96E-03 527 4c 29 Table 14: Kinetic and affinity determinations for anti-NKp46 OmnidAb clones merged with bin assignments and clonal lineage IDs. Results for 102 unique-sequence anti-NKp46 HcAbs. n / d = not determined. Atty. Dkt: OMNI-002WO EXAMPLE 10 DEVELOPABILITY ASSESSMENT OmnidAb antibodies specific for PGRN and NKp46 were evaluated in sdAb-Fc format for various development metrics, such as thermal stability, analytical size exclusion chromatography (aSEC), and self-interaction using affinity-capture self-interaction nanoparticle spectroscopy (AC-SINS). All of the antibodies specific for NKp46 exhibited high Tm and Tagg, as determined by thermal stability analysis (FIG.7A and 7B). The aSEC analysis confirmed that all the antibody hits showed a homogeneous monomeric peak corresponding to a size of approximately 70 kDa based on elution time (FIGS.11A and 11B), the expected size for this format, indicating no aggregation of the antibody preparations. AC-SINS is an assay developed to monitor the propensity for antibody self-association. Self- association at high concentrations can result in developability challenges such as poor solubility, aggregation, and high viscosity. Δλmax <5 nm was defined as a fairly stringent limit for selection of only well-behaved monoclonal antibodies (mAbs) for downstream development.The AC-SINS studies revealed that most identified OmnidAb antibodies displayed minimal plasmon shifts (Δλmax < 5 nm), supporting their potential for developability. As references, eight human and humanized antibodies in late-stage clinical trials and one FDA-approved humanized VHH-Fc (caplacizumab) were included (FIG. 7C). All of these clinical antibodies have Δλmax values less than 5 nm, confirming their good developability. Analysis of a set of antibodies confirmed in previous literature to have poor AC-SINS scores and all showed Δλmax values greater than 5 nm, suggesting strong self-association in phosphate- buffered saline (PBS) at pH7.4. DISCUSSION Disclosed herein is a heavy chain-only chicken expressing human variable regions, referred to as OmnidAb chicken. Expression of HcAbs in the intact immune system requires engineering of the variable region, which lacks a VL partner, and dealing with the CH1 domain, which lacks a CL partner. Our engineered single domain variable region framework in the VHH3 transgene was able to express well as an autonomous VH region, and for the CH1 domain a light chain consisting of only the constant region was provided, the tLCi transgene. However, upon expression of the VHH3 transgene,n OmnidAb, it was discovered that the tLCi chaperone light chain was not required for B-cell development or antibody expression in these birds. The tLCi transgene did have some effect however, as somewhat higher antibody expression was observed in the tLCi birds (FIG.2A), but the homozygous IgL knock-out birds were still able to produce adequate levels of functioning B cells and antibodies. The mechanism Atty. Dkt: OMNI-002WO remains unknown, but this suggests that tLCi aided in B-cell development or expression of the heavy chain, yet was not required when the variable region was engineered for single domain expression. Previous work with heavy chain-only wild-type chickens showed that expression of tLCi was essential for proper B-cell development and heavy chain expression. It was somewhat surprising that the wild- type, non-engineered chicken VH region, which normally pairs with the VL, could readily express as a HcAb both in vivo and as recombinant antibody. In contrast, when a non-engineered fully human VH transgene was combined with the tLCi transgene in birds, no expression or B-cell development was observed. Thus, the engineered framework in the OmnidAb birds was essential for expression, support of B-cell development, and subsequent antibody discovery of human HcAbs in transgenic chickens. The introduction of VHH3 did not resolve the birds’ inability to class switch to IgY, but it was observed that the antigen-specific IgM antibodies produced were affinity matured with diverse epitope coverage. The optimized single VH scaffold in the OmnidAb birds was designed to be maintained by the process of gene conversion, in which the pseudogenes upstream of the single functional gene in the transgene contain the same stabilizing changes. For the most part, the stabilizing changes engineered into the VH scaffold were maintained, and the biophysical characterization of the antibodies suggest that these changes provide important stability and solubility to the antibodies. The one notable exception was in the hallmark “tetrad” in FR2, where random mutation occurred despite the propensity of gene conversion to erase it. It was speculated that the high level of mutation to a variety of different amino acids (AA), not just of one type, suggests that those residues may be involved in antigen contact. Another possible scenario is that the elongated CDR3 in HcAbs may fold down and contact FR2, with variation in these contacts. These FR2 mutations would thus be selected for improving biophysical characteristics of the variable region such as stability or lack of aggregation rather than participating in antigen-binding. Structural studies will be necessary to investigate these ideas further. High levels of diversity were introduced by gene conversion in the CDRs, as designed. CDR3 lengths were centered around the germline length of 17 residues, even though most of the pseudogenes have longer CDR3s, consistent with most gene conversion events involving partial sequence replacement rather than complete CDR replacement. Although OmnidAb antibodies showed a high level of sequence variation, from both gene conversion and somatic hypermutation, they had low predicted immunogenicity. The natural in vivo B-cell selection process for these diverse sequences may underscore the viability of these changes as they favor good biophysical properties, such as high-level expression, stability, and solubility. A subset of the NKp46-specific antibodies activated IFNγ release. For multispecifics, if the aim is to use the receptor as a tether for targeting of an NK or T cell to a tumor, receptor activation could potentially be disadvantageous. Therefore, a cohort of antibodies displaying functional diversity could Atty. Dkt: OMNI-002WO be an advantage during an antibody discovery campaign to give options compatible with custom molecular formats and geometries designed to achieve the intended mechanism of action. In self- interaction studies, the anti-NKp46 antibodies seemed to have slightly elevated self-association as compared to the anti-PGRN clones, although they were still within an acceptable range for developability. The different target specificity could have resulted in these differences based on the paratopes that evolved for the NKp46 clones. No correlation with GRAVY was observed. As with the other transgenic chicken platforms OmniChicken and OmniClic, the OmnidAb chickens recognized a broad range of epitopes, consistent with the superior recognition of human targets by the chicken as a host immunization species, due to its divergent phylogenetic distance22. OmnidAb chickens also produced clones with a range of affinities, including high affinities showing KD values in the single digit nM range. When designing a bispecific, kinetic diversity is an advantage since moderate affinity may be sufficient for therapeutic effect, and since avidity effects with 2+2 bispecifics could produce unwanted or excessive activation if the binding affinity were too high. For PGRN, it was observed a relatively high number of clones that targeted the small paragranulin (p) domain, many of which had a short CDR3 of only nine residues. PGRN is composed of seven ~55 AA highly disulfide- bridged granulin domains (GRN) separated by linker regions (P1-P7) of 10-26 AA. At the N-terminus is the 25 AA p domain with a linker of 15 AA to the first granulin domain, GRN-G. Based on the chimera experiments, the p binders could possibly bind the linker as well. There is no structural information for PGRN, so it is unknown whether the linkers would be accessible to antibody binding. For NKp46, it was observed a broad epitope coverage that overlapped with and extended beyond that of four literature benchmark clones, each targeting non-overlapping epitopes. Five distinct, non-overlapping epitope bins were determined, of which three (bins 1, 2, and 3) overlapped with the benchmarks (which were assigned to bins 1a, 1e, 2c, and 3b) and two (bins 4 and 5) were not represented by the benchmarks. This suggests that the HcAb format in OmnidAb chickens may enable targeting of epitopes inaccessible to the other chicken strains expressing conventional heavy and light-paired antibodies. Taken together, these two case studies on unrelated model antigens demonstrate that OmnidAb chickens can produce clones with broad epitope coverage, a range of affinities, including high affinities in the low nM range, and favorable developability metrics. While the present invention has been described with reference to the specific embodiments thereof, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of Atty. Dkt: OMNI-002WO matter, process, process step or steps, to the objective, spirit and scope of the present invention. All such modifications are intended to be within the scope of the claims appended hereto.

[0002] TABLE 1: VHH CDR sequences Clone ID HCDR1 SEQ ID HCDR2 SEQ ID HCDR3 SEQ IDCL-6623 GFTFSSYA 1 INGGGGAT 97 AAGTDTGDSGGSGKFVY 19345678901234567890123456789012345678901234567 CL-3560 GFSFSGYA 46 INTDGTRTY 142 ARVAAGSGGSGGRWPLDY 238CL-3559 GFTFSSYD 47 TYTRSNT 143 SAAPGSGGSGGSGKIDY 239012345678901234567890123456789012345678901234 CL-2410 GFTFSSHP 93 ISETGKKT 189 ARATIGSGGIGDVKFDY 285CL-2408 GFTFSSYN 94 FYKSGNT 190 AAASGNGGSGGSGKIDY 28678

[0003] TABLE 2: VHH sequences Clone ID SEQ ID SequenceEVQLVESGGGSVQPGGSLRLSCTASGFTFSSYAMGWMRQAPGKETEVVSVIN D N G N G N D G G D G Y I Y F Y I Y I D G D G Y G Y I D G EVQLVESGGGSVQPGGSLRLSCVASGFTFPSYWMGWSRHAPGKEKEGVSMID CL-5021 304GNGIRTAYADSVKGRFTVSRDNAKNTLYLQMNSLKPEDTAIYYCGAAAVNGG H R H R D G D G D G H R Y I D G Y R Y S S V N G S S N G EVQLVESGGGNVQPGGSLRLSCAASGFTFSSYNMGWVRQAPGKKREVVAVIY CL-3618 319TRSNTWYADSVKGRFTISRDNAKNTVYLQMNSLKPEDTAVYYCSAAPGSGGS Y S N G K G V L K G S E N G R S N G G G D G G G S V H F EVQLVESGGGSVQPGGSLRLSCAASGFSFSGYAMTWFRQAPGKEREDVSGIN CL-3560 334TDGTRTYYGADSVKGRFTISRDNVNNTVYLQMNSLKPEDTAVYYCARVAAGS Y S G G N G N G N F N G S V H G Y S D G Y G K G Y S R G EVQLVESGGGSVQPGGSLRLSCAASGFNFSNYWMFWVRQAPGKENVAVSSID CL-3479 349TTTRTAYADYVKGRFTISRDNTKNTVYLQMNSLKPEDTALYYCAATTDSGGS Y G Y S D G Y S S V G S N D Y V Y G S A S G N E K E Y G AVTLVESGGGSVQPGGSLRLSCAASGFTFSSYGMRWIRQAPGKEREAVAAIY CL-2491 364SDGTIYYAGSVKGRFTISRDNAKNTVYLQMNSLKPEDTAVYYCSKDGSGGSG S P Y S S G S G F G S G N G Y G D E Y G I G S S N G N G AVTLVESGGGSVQPGGSLRLSCAASGFTFSSYGMRWIRQAPGKEREAVAAIY CL-2416 379SGGSTYYADSVKGRFTISRDNAKNTVYLQMNSLKPEDTAVYYCAKDASAGSG S G S G Y S D E G E

[0004] TABLE 3: Rat VH CDR sequences Clone ID HCDR1 SEQ ID HCDR2 SEQ ID HCDR3 SEQ ID18203 GGSFSGYY 385 INHTGST 630 ARDTMVTTDHYHGMDV 87567890123456789012345678901234567890123456789 19486 GGSISSGGYY 430 IFYSGTT 675 ARVPGNWFDP 9204642 GGSINSAGYF 431 IFYSGTT 676 VRTPGNWFDP 921234567890123456789012345678901234567890123456 7059 GFNFSSHA 477 ISGSGGRT 722 AKGGSYYSNWADY 96716789 AFTFSSYA 478 ISGSGGRT 723 AKGGSYYSNWADY 968901234567890123456789012345678901234567890123 Rat_35 GYTFTSYD 524 MNPSSGNA 769 ARGRLVVASNFFDY 1014Rat_36 GGSINSAGYF 525 IYYSGTT 770 ARTPGNWFDP 1015678901234567890123456789012345678901234567890 Rat_83 GYSISSGGYY 571 IFYSGTT 816 ARDSWGGAFAI 1061Rat_84 GASVNSSGYY 572 IYYSGTT 817 ARDSWGGAFAI 1062345678901234567890123456789012345678901234567 Rat_143 GYTFTSYD 618 MNPNSGNA 863 ARGRLVVASNFFDY 1108Rat_144 GYTFTSFD 619 MNPNSGNT 864 ARGRVVVAGNFFDY 11090123456789

[0005] TABLE 4: Rat VH sequences Clone ID SEQ ID SequenceQVQLQQWGAGLLKPSETLSLTCAVYGGSFSGYYWSWIRQPPGKGLEWIGEIN D N V S M N A S F N P L Y Y G S N S M S F Y W T G S G N P QVQLVQSGAEVKKSGSSVKVSCKSSGGTFSSYAISWIRQAPGQGPEWMGGII 14580 1135PFFGTTNYAQKFQGRVTITADESTSTAYMELTNLKSEDTAVYYCASDNYDFL N A I D I S S L S L S Y N R W N Y L Y W Y W Y W Y W Y W QVQLQESGPGLVKPSQTLSLTCTVSGGSINSAGYFWSWVRQHPGKGLEWIGY 20083 1150IYYSGTTYYNPSLKSRVTISLDTSKNQFSLTLTSVTAADTAIYYCARVPGNW Y W Y L Y W Y W Y L Y L Y L Y L Y W Y L Y L Y W Y W Y L QVQLQESGPGLVKPSQTLSLTCTVSGGSISSGGYYWSWIRQHPGKGLEWIGY 19486 1165IFYSGTTYYNPSLKSRVTISLDTSKNQFSLTLTSVTAADTAIYYCARVPGNW Y W Y L Y W Y W Y W Y W Y W Y W Y W Y L Y W Y L Y W Y W QVQLQESGPGLVKPSQTLSLTCTVSGGSISSGGYYWSWIRQHPGKGLEWIGY 19403 1180IFYSGTTYYNPSLKSRVTISVDASKNQFSLTLTSVTAADTAIYYCARVPGNW Y L Y L Y W Y W Y W Y L Y L Y L Y L Y W Y W Y W Y L Y L EVQLVQSGAEVKKPGESLKISCKGFGYNLTTYWIGWVRQMPGKGLEWMGIIY 15697 1195PGDSDTRYSPSFQGQVTISADKSISTAYLQWTSLKAADTAIYFCARPNIVIL Y W Y L Y L Y L Y L Y L Y L Y L Y L Y L Y L S S S S S S EVQLLESGGGLVQPGGSLRLSCAASGFTFSSQAMNWVRQAPGKGLEWVSAIS 10828 1210GSGGRTYYVDSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAKGGSYYS S S S S S S S S S S S S Y G Y G Y G Y G Y G Y G Y G Y G QVQLQESGPGLVQPSQTLSLTCTVSGASVNSSGYYWSWIRQHPGKGLEWIGY 16794 1225IYYSGTTYYNPSLRSRVTISVDTSTNQFSLILSSVTAADTAVYYCARDSWGG N A N A N A N A N A N A N A N A N A N A N A N A N A N A QVQLVQSGAELKKPGASVKVSCKASGYTFTSYDINWVRQATGQGLEWMGWMN 1240 PNSGNADYAQMFQGRVTMTRNTSINTAYMELSSLRSEDTAVYYCARGRVVVA N A N A N A N A N A N A N A N A N A N A N A N A N A N A QVQLVQSGAKVKKPGASVKVSCKASGYTFTSYDINWVRQATGQGLEWMGWVN 1255 PNSGNADYAQMFQGRVTMTRNTSISTAYMELSSLRSEDTAVYYCVRGRLVVA N A N A N A N A Y W Y W Y W Y W Y W Y W Y W Y W Y W Y W QVQLQESGPGLVKPSQTLSLTCTVSGGSISGGGYYWSWIRQHPGKGLEWIGY 1270 IYYSGTTYYNPSLKSRLTISVDTSNNQFSLRLSSVTAADTAVYYCARVPGNW Y W Y W Y W Y W Y W Y W Y W Y W Y W Y W Y W Y W Y W Y W QVQLQESGPGLVKPSQTLSLTCSVSGGSISSGGYYWSWIRQHPGKGLEWIGY 1285 IYYSGTIYYTPSLKSRVTISLDTSKNQFSLKLSSVTAADTAVYYCARTPGNW Y L Y L Y L Y L Y L Y L C L Y L Y L Y L Y L Y L Y L Y L EVQLVQSGAEVKKPGESLKISCKGSGYNFTTYWIGWVRQMPGKGLEWMGIIY 1300 PGDSDTRYSPSFQGQATISADKSISTAYLQWTSLKASDTAMYFCARPNIVKL Y G Y G Y G Y G Y G Y G Y G Y G Y G S S S S S S S S S V QVQLQESGPGLVKPSQTLSLTCTVSGGSISSGGYYWSWIRQHPGKGLEWIGY 1315 IFYSGTTYYNPSLKSRVTISVDASKNQFSLKLSSVTAADTAVYYCVRTPGNW Y W Y W Y W Y W Y W Y L Y L Y L Y L Y L Y L Y L S V S S EVQLLESGGGLVQPGGSLRLSCAASGFNFSSHAMNWVRQAPGKGLEWVSAIS 1330 GSGGRTYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAKGGSYYS S S S S S S S S S S Y W Y W Y W Y W Y W Y W Y W Y W Y W QVQLQESGPRLVKPSQTLSLMCTVSGGSINSAGYFWSWIRQHPGKGLEWIGY 1345 IYYSGTTYYNPSLRSRVIISLDTSKNQFSLKLSSVTAADTAVYYCARTPGNW N A N A N A N A N A N A N A N A N A F F F F Y G Y G Y G QVQLQESGPGLVKPSQALSLTCNVSGYSISSGGYYWSWIRQHPGKGLEWIGY 1360 IFYSGTTYYNPSLKSRVTISVDTSTNQFSLILSSVTAADTAVYYCARDSWGG Y G Y G Y G Y L

[0006] TABLE 5: Rat binding data Clone ID KD (M) Clone ID KD (M) Clone ID KD (M) Clone ID KD (M)18203 3.68E-08 14357 1.61E-08 Rat_22 3.60E-08 Rat_86 9.96E-0977778779998888788898787777999999999888888888 19486 5.18E-08 Rat_3 1.75E-08 Rat_67 5.39E-08 Rat_144 1.13E-084642 1.00E-07 Rat_4 1.36E-08 Rat_68 1.51E-07 Rat_148 7.40E-088 087 88 98 98 98 98 78 78 888 98987

[0007] TABLE 6: Chicken VH CDR sequences Clone ID HCDR1 SEQ ID HCDR2 SEQ ID HCDR3 SEQ ID719 GFTFSSYS 1365 INWNSDTY 1535 AKGINGEYFDY 170567890123456789012345678901234567890123456789 1021 GFIFTGYD 1410 INWNTGGTT 1580 VKVQATRHHFDY 175029 GFTFDDYA 1411 ISWNSGNI 1581 AKQGGNGPTYFDY 1751234567890123456789012345678901234567890123456 1209 GFIFSGYD 1457 INWNSGDTT 1627 AKLQATRYYFDY 17971104 GFIFSGYD 1458 INWNSGDTT 1628 AKLQATRYYFDY 1798901234567890123456789012345678901234567890123 779 GFRFDDYP 1504 INWNSAGI 1674 TKGDSWNHYFDY 18440756_v2 GFIFSGYD 1505 ISWNTGGTT 1675 AKLQATRYYFDY 184567890123456789012345678901234

[0008] TABLE 7: Chicken VH sequences Clone ID SEQ ID SequenceNW FD NW FD NW FD NW FD NW FD NW FD NW FD NW FD NW FD NW FD NW FD NW FD NW FD NW FD NW FD EVHLLESGGGLVQPGGSLRLSCAASGFTFSSYSMTWVRQAPGKGLEWVSVINW 1441 1890NSDTYYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAKGINGEYFD NW FD NW FD NW FD SW DY KW GY KQ YW NW YF NW YF NW YF NW YF NW YF NW YF DR EY DR QY EVQLLESGGGLVQPGGSLRLSCAASGFTFSGSTMSWVRQAPGKGLEWFSAIDR 1905GGRTYHADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARTRLNNYFEY DR EY DR EY NW YF NW YF NW YF NW YF NW YF NW YF NW DY NW YY NW YY SW YY NW YF DW YH EVQLLESGGGLVQPGGSLRLSCAASGFIFTGYDMSWVRQAPGKGPEWVAYINW 1021 1920NTGGTTYYADSVKGRFSISRDNYKNTLYLQMNSLRAEDTAVYYCVKVQATRHH SW TY YS SW YT YW GW YF SW AF KW AF SW AF TT TH TT TH GL DY AT YW AT YW AT YW NS TR EVQLLESGGGLVQPGGSLRLSCAASGFTFSDYWMSWVRQAPGKGLEWVSAISS 757 1935SRNVHNTYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAKILVTWN SS WN YR YF YR YF YR YF TG DY TG DY TG DY TS ND YS YF SI DW SF DW YS KW AW PT AW PT EVQLLESGGGLVQPGGSLRLSCAASGFTFDDYAMTWVRQAPGKGLEWVSSIGW 1821 1950NGGNIFYADSVKGRFTISRDNSKNTLYLQMNSLTAEDTAVYYCARIGLYLFDY GW DY GW DY ST HY SW FD YS YW SW WG NW YF NW YF YS YW SS YW SW LF YS YN NW YF NW YY EVQLLESGGGLVQPGGSLRLSCAASGFIFSGYDMSWVRQAPGKGLEWVAYINW 1668 1965NSGDTTYYADSVKGRFTISRDNYENTLYLKMNSLRAEDTAVYYCAKLQATRYY NW YY NW YY NW YY NW YY NW YY SW YY NW YH DW YH NW FD SI DW SW HY NW YY SW HY SI DW EVQLLESGGGMVQPGGSLRLSCAASGFIFSGYDMSWVRQAPGKGLEWVAYINW 1534 1980NTGGTTYYADSVKGRFTISRDNSWNTLYLLMNSLRAEDTAVYYCAKVQATRYY NW YY SI DW NW YY SI DW NW YY NW YH NW YY NW YF NW YF NW YF NW YF NW FD NW YF GL DY EVQLLESGGGLVQPGGSLRLSCAASGFIFSGYDMSWIRQAPGKGLEWVAYINW 1035 1995NTGDTTYYADSVKGRFTISRDNYENTLYLQMNSLRAEDTAVYYCAKLQATRYY NW HH SI DW SW YY NW YF NW YF GL DY NW YY SW HY NW YY NW YY SW YY NW YF NW YF NW YY EVQLLESGGGLVQPGGSLRLSCEASGFIFTGYDMSWVRQAPGKGLEWVAYINW 825 2010NTGGTTYYADSVKGRFTISRDNSKNTLYLQMNSLRVEDTAVYYCAKVQATRHH NW YH NW YY NW YF NW YF SW YY SI DW NW YF NW YF NW YF NW YF NW YF NW YF NW YF NW YF EVQLLESGGGLVQPGGSLRLSCAASGFIFGDYPMNWVRQAPGKGLEWVSAINW 54384 2025NGAGIDYADSVKGRFTISSDNSKNTLYLQMNSLTAEDTAVYYCAKGNSWNHYF NW YF NW YF NW YF NW YF NW YF NW YF NW YF NW YF NW YF NW YF NW YF NW YF SR EL NW YF EVQLLESGGGLVQPGGSLRLSCAASGFIFGDYPMNWVRQAPGKGLEWVSAINW 23486 2040NGAGIDYADSVKGRFTISRDNSKNTLYLQRNSLTAEDTAVYYCAKGNSWNHYF NW YF NW YF NW YF NW YF

[0009] TABLE 8: Chicken binding data Clone ID KD (M) Clone ID KD (M) Clone ID KD (M) Clone ID KD (M)719 7.53E-08 1021 3.08E-09 1668 6.31E-10 825 8.11E-100989990999999999999900989900009999 TABLE 9: Bovine ultra-long CDR H3s Clone ID SEQ ID SequenceTTVLQTTKKSCPDGWTYSSGCDSGYGCGCCDCCINRGSAVGGSTGVGCTSYSF 2045 F F F F E E G E D S

[0010] TABLE 10: Additional VHH CDR sequences Clone ID HCDR1 SEQ ID HCDR2 SEQ ID HCDR3 SEQ ID45678901234567890123456789012345678 TABLE 11: Additional VHH sequences Clone ID SEQ ID SequenceTY G TY G YY T T VT YY GT YY Q SY G YY GT TA V TY G YY W NG G TY W RT Y ST G EVTFVESGGGSVQPGGSLRLSCAASGFTFSNFWMTWFRQAPGKEREAVSTINDDGNR CL-27055 2174TYYADSVKGRFTISRDNANDTVYLQMSTLKPEDTAVYYCARAIKISPYTGGIGGGGTFDY R Y TY Q T G ST G RT W TY Q ST G AT G RT Y T T Y GQ RI V NT T TA Q EVQLVESGGGSVQSGGSLRLSCAASGFSFSSRGMSWVRQAPGKEREAVSAINWNGNT CL-25088 2189TWYADSVKGRFTISRDNAKNTVYLQMNSLKPEDTAVYYCATLLNEGRIDNRGQGTQVT AR T A Q T T AT T

Claims

Atty. Dkt: OMNI-002WO CLAIMS What is claimed is:

1. A polypeptide comprising:a VHH domain comprising: (a) CDR1, CDR2 and CDR3 regions that are identical to the CDR1, CDR2 andCDR3 regions of a VHH antibody selected from Tables 1 and 10; or (b) CDR1, CDR2 and CDR3 regions that are otherwise identical to the CDR1,CDR2 and CDR3 regions of a VHH antibody selected from Tables 1 and 10 except for up to 10 amino acid substitutions in the collective CDR regions; wherein the VHH domain binds to NKp46.

2. A polypeptide comprising:an antibody binding domain comprising: (i) a heavy chain variable domain comprising CDR1, CDR2 and CDR3 regionsthat are identical to the heavy chain CDR1, CDR2 and CDR3 regions of a common light chain antibody selected from Table 3 or 6 or are otherwise identical to the heavy chain CDR1, CDR2 and CDR3 regions of a common light chain antibody selected from Table 3 or 6 except for up to 10 amino acid substitutions in the collective CDR regions; and (ii) a light chain variable domain comprising CDR1, CDR2 and CDR3 regionsthat are identical to the light chain CDR1, CDR2 and CDR3 regions of the selected common light chain antibody or are otherwise identical to the light chain CDR1, CDR2 and CDR3 regions of the selected common light chain antibody except for up to 10 amino acid substitutions in the collective CDR regions, wherein the antibody binding domain binds to NKp46.

3. A polypeptide comprising:a knob domain comprising an amino acid sequence that is the same as or comprises up to 10 amino acid substitutions relative to the knob domain of an ultralong CDR3 domain selected from Table 9.Atty. Dkt: OMNI-002WO 4. The polypeptide of claim 1, 2 or 3, wherein:the amino acid sequence of the VHH domain is at least 90% identical to the variable domain of the selected VHH antibody; or the antibody binding domain comprises a heavy chain variable domain that is at least 90% identical to the heavy chain variable domain of the selected common light chain antibody and a light chain variable domain that is at least 90% identical to the light chain variable domain of the selected common light chain antibody; or the knob domain comprises an amino acid sequence that is at least 90% identical to the sequence of an ultralong CDR3 domain selected from Table 9.

5. The polypeptide of any of claims 1-4, wherein:the amino acid sequence of the VHH domain is at least 95% identical to the variable domain of the selected VHH antibody; the antibody binding domain comprises a heavy chain variable domain that is at least 95% identical to the heavy chain variable domain of the selected common light chain antibody and a light chain variable domain that is at least 95% identical to the light chain variable domain of the selected common light chain antibody; and the knob domain comprises an amino acid sequence that is at least 95% identical to the sequence of an ultralong CDR3 domain selected from Table 9.

6. The polypeptide of any prior claim, wherein the VHH domain or antibody bindingdomain is humanized.

7. The polypeptide of any prior claim, wherein the antibody binding domain is a scFv orFab.

8. The polypeptide of any prior claim, wherein the polypeptide is a multispecific bindingmolecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain.

9. The polypeptide of claim 8, wherein the at least one other binding domain recognizes acancer antigen or a viral antigen.Atty. Dkt: OMNI-002WO 10. The polypeptide of claim 9, wherein the cancer antigen is CD19, CD20, BCMA, ALPP,CS1 (SLAMF7), CLDN18.2, AXL, ROR2, TM4SF1, ICAM-1, L1CAM (CD171), CD4, CD5, CD7, CD10, CD38, CEA, FLT3, CD70, CD30, CD37, or CD147.

11. The polypeptide of any prior claim, wherein the polypeptide is a bispecific bindingmolecule that comprises (i) the VHH domain, the antibody binding domain or the knob domain and (ii) a binding domain that recognizes a cancer antigen or a viral antigen.

12. The polypeptide of any prior claim, wherein the polypeptide is a bispecific bindingmolecule that comprises (i) the VHH domain, the antibody binding domain or the knob domain, (ii) a binding domain that recognizes a cancer antigen and (iii) either a binding domain that recognizes a co- stimulatory receptor on NK cells or a binding domain that recognizes a second cancer antigen or a second viral antigen.

13. The polypeptide of claim 12, wherein the co-stimulatory receptor is 2B4, DNAM1, orCD2.

14. The polypeptide of any of claims 9-13, wherein the cancer antigen is a blood cancerantigen.

15. The polypeptide of claims 9-13, wherein the cancer antigen is a solid tumor antigen.

16. The polypeptide of any prior claim, wherein the polypeptide is conjugated to apharmacologically active agent.

17. A pharmaceutical composition comprising:a) the polypeptide of any prior claim or a polynucleotide, e.g., an RNA, encoding thesame; and b) a pharmaceutically acceptable carrier.

18. The pharmaceutical composition of claim 17, wherein the polypeptide is a multispecificbinding molecule that comprises the VHH domain, the antibody binding domain or the knob domain andAtty. Dkt: OMNI-002WO at least one other binding domain that binds to a cancer antigen.

19. A method of increasing binding between an NK cell and a cancer cell, comprisingincubating the NK cell and a cancer cell with a polypeptide of any of claims 1-16, wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain that binds to a cancer antigen on the cancer cell.

20. A method of killing a cancer cell, comprising contacting the cancer cell with an NK celland a polypeptide of any of claims 1-16, wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain that binds to a cancer antigen on the cancer cell.

21. A method of treatment comprising administering a polypeptide of any of claims claim 1-16 or a polynucleotide encoding the same (e.g., an RNA) to a subject that has cancer, wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain that binds to a cancer antigen on the cancer cell.

22. A method of increasing binding between an NK cell and a virally-infected cell,comprising incubating the NK cell and a virally-infected cell with a polypeptide of any of claims 1-16, wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain that binds to a viral antigen on the virally-infected cell.

23. A method of killing a virally-infected cell, comprising contacting the virally-infectedcell with an NK cell and a polypeptide of any of claims 1-16, wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody binding domain or the knob domain and at least one other binding domain that binds to a viral antigen on the virally-infected cell.

24. A method of treatment comprising administering a polypeptide of any of claims 1-16 ora polynucleotide encoding the same (e.g., an RNA) to a subject that has a viral infection, wherein the polypeptide is a multispecific binding molecule that comprises the VHH domain, the antibody bindingAtty. Dkt: OMNI-002WO domain or the knob domain and at least one other binding domain that binds to a viral antigen on a virally-infected cell.

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