Functionalized FC receptor polypeptides and covalent FC complexes including the same

Abstract

Provided herein are, inter alia, polypeptides and covalent complexes including the same, with multivalent binding specificity. The polypeptides include an Fc receptor portion / domain (e.g., a CD16 domain, a CD32 domain, a CD64 domain and variants thereof) with a cysteine amino acid substitution capapble of forming a disulfide linkeage with a second cysteine amino acid substitution in an Fc domain (e.g., an Fc domain of IgG1, IgG2, IgG3, IgG4) thereby forming a covalent complex with multivalent binding ability. The compositions provided herein exhibit highly specific binding with reduced or no endogenous Fc receptor binding activity thereby resulting in therapeutics that lack undesirable side effects.

Description

PATENT Attorney Docket No.: 048440-211001 WOFunctionalized Fc Receptor Polypeptides and Covalent Fc Complexes including the sameRELATED APPLICATION DATA

[0001] This application claims the benefit of priority’ under 35 U. S. C. § 119(e) of the U. S. Patent Application No. 63 / 745,745, filed on January 15, 2025, which is hereby incorporated by reference in its entirety and for all purposes.SEQUENCE LISTING

[0002] The material in the accompanying Sequence Listing is hereby incorporated by reference in its entirety. The accompanying file, named “048440-21100 lWO_SL_ST26.xml” was created on January 15, 2026 and is 288,732 bytes.BRIEF SUMMARY

[0003] In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 106 of CD 16.

[0004] In another aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD32 domain including a cysteine at a position corresponding to amino acid position 121 of CD32.

[0005] In another aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 102 of CD64.

[0006] In another aspect is provided a covalent complex including: (i) a polypeptide provided herein including embodiments thereof: and (ii) an Fc domain including a second cysteine;wherein the polypeptide is covalently bound to the Fc domain through a disulfide linkage between (a) the cysteine at a position corresponding to amino acid position 106 of CD 16, (b) the cysteine at a position corresponding to amino acid position 121 of CD32 or (c) the cysteine at a position corresponding to amino acid position 102 of CD64 and the second cysteine.

[0007] In another aspect is provided a recombinant nucleic acid sequence encoding the polypeptide including embodiments thereof

[0008] In another aspect is provided an expression vector including the nucleic acid sequence provided herein including embodiments thereof.

[0009] In another aspect is provided a cell including the expression vector provided herein including embodiments thereof.

[0010] In an aspect is provided a pharmaceutical composition including the polypeptide provided herein including embodiments thereof and a pharmaceutically acceptable excipient.

[0011] In another aspect is provided a method of treating cancer in a subject in need thereof, the method including administering to the subject a therapeutically effective amount of the polypeptide provided herein including embodiments thereof, thereby treating cancer in the subject.

[0012] In one aspect, a multivalent ligand binding complex is provided. The complex includes a first protein dimerizing domain non-covalently bound to a second protein dimerizing domain to form a first ligand binding domain, where the first protein dimerizing domain is covalently bound to a second ligand binding domain through a first chemical linker, the second protein dimerizing domain is covalently linked to a second ligand binding domain enhancer through a second chemical linker, and the second ligand binding domain is covalently bound to said second ligand binding domain enhancer through a third chemical linker.

[0013] In another aspect, a multivalent ligand binding complex is provided. The complex includes a first protein dimerizing domain non-covalently bound to a second protein dimerizing domain to form a first ligand binding domain, where the first protein dimerizing domain is covalently bound to a second ligand binding domain enhancer through a first chemical linker, the second protein dimerizing domain is covalently linked to a second ligand binding domainthrough a second chemical linker, and the second ligand binding domain is covalently bound to the second ligand binding domain enhancer through a third chemical linker.

[0014] In another aspect, a pharmaceutical composition is provided. The pharmaceutical composition includes a complex of any one of the previous embodiments and a pharmaceutically acceptable excipient.

[0015] In one aspect, an isolated nucleic acid is provided. The nucleic acid encodes a peptide provided herein including embodiments thereof.

[0016] In another aspect, an expression vector including the nucleic acid provided herein including embodiments thereof is provided. In embodiments, the expression vector is a viral vector. In embodiments, the virus is a lentivirus or onco-retrovirus.

[0017] In another aspect, a T lymphocyte including the expression vector provided herein including embodiments thereof is provided.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 shows an exemplary schematic of the polypeptide described herein bound to CD 16. The Fc region of an IgG binds to FcRg(I-III) with detectable affinities. We can generate a covalent complex by strategically mutating select residues on each to cysteine to create a disulfide. Super position of Fc-FcgR complexes from the pdb ( lt89, 6eaq, 5xje, 5yc5, 7uru, 5xjf,5d6d, 3wn5 - using CD16 for the alignment) indicate one set of residues (one from the Fc and one from the FcgR) are well poised to create a disulfide. Using the numbering in the PDB file, 1189, A330 in the Fc and 188 in the FcgR are in close proximity. Mutations of these residues in the structure and selecting favorable rotamers using molecular visualization systems (e.g., Pymol) indicates the distance between sulfurs of each cysteine is 2.1 A. A distance of disulfide bond is 2.05 A.

[0019] FIGS. 2A-2C show binding of IgG and FcR isoforms. There are multiple forms of FcgR that bind IgG with different affinities. Nearly all bind to IgG3 with relatively high affinity. This is likely due to the extra spacer between the Fabs and the Fc. IgGl binds with moderate affinity to most isoforms. Moreover, there is a common isoform of FcgRIIIA, V158 and F158. V158 binds to the IgGl with higher affinity than 158F. Of note, people homozygous with V158typically have beter outcomes using, for example, therapeutic mAbs where the MOA is ADCC / ADCP - presumably due to the higher affinity. IgG2 show the least affinity to the FcgR isoforms with the exception of FcgRIIA(H131). IgG4 also shows reduced affinity to the FcgR isoforms with the exception of FcgRl. SPR studies of all isoforms further confirms these findings. As this interaction is critical to MOA, great efforts have been put forth to modulate the affinity. This includes protein engineering and carbohydrate modification such as defucosylation. These mutations can also be incorporated into polypeptides provided herein including embodiments thereof and may enhance the formation and stability of the disulfide bridged molecule.

[0020] FIGS. 3A-3H show data from size exclusion chromatography (SEC) experiments. Fc, FcgR and Fc / FcgR complex were run respectively at size-exclusion chromatography (HiLoad 16 / 600 Superdex 200 pg, Cytiva Lifesciences), room temperature in PBS after purifying from affinity chromatography. FIG.3A: h!gGl-Fc2 expressed alone (expected size: 50 kDa). FIG.3B: hIgGl-Fc2 A330C expressed alone (expected size: 50 kDa). FIG. 3C: hIgGl-Fc2-2X A330C expressed alone (expected size: 50 kDa). FIG. 3D: h!gGl-Fc2 co-expressed with CD16aV-His I106C at 1:1 ratio (expected size: 75 kDa). FIG. 3E: h!gGl-Fc2 A330C coexpressed with CD16aV-His I106C at 1:1 ratio (plasmid ratio) (expected size: 75 kDa). FIG.3F: h!gGl-Fc2-2X A330C co-expressed with CD16aV-His I106C at 1:1 ratio (expected size: 75 kDa). FIG. 3G: CD16aV-His I106C. FIG. 3H: Yield of SEC experiments for each of the Fc, FcgR, and Fc / FcgR complexes.

[0021] FIG. 4 shows an SDS Page gel of fractions from a size exclusion chromatography purification (NR - non reducing / R - reducing). Note in lanes 7 and 9 a shift to 75kd in the nonreducing gel and a collapse in the presence of reducing agent. This indicates the formation of a disulfide bond across the modified Fc and FcR interface. Also note, both plasmids (one encoding the Fc and another encoding the FcgR) are transfected into the cell at a ratio of 1 to 1. This was observed in size exclusion chromatogram where two peaks were observed. The SDS-PAGE shown above are fractions from the column (F15-16 and F14). In the non-reduced gel, lanes 7 and 9 run at a higher molecular weight, indicative of the formation of a disulfide bond.

[0022] FIGS. 5A-5B show h!gGl-Fc2 A330C / CD16aV-His I106C complex stability’ in PBS (FIG. 5A) and mouse serum (FIG. 5B).

[0023] FIGS. 6A-6C show protein thermal shifts of complexes provided herein. Differential Size Fluorescence is a viable method to confirm stability expected w ith the disulfide bond. The IgGl-Fc only (FIG. 6A), with the cysteine substitution at 330 (FIG. 6B), and with the cysteine substitution and the additional mutations (FIG. 6C) to enhance the binding affinity were individually tested. The Fc only and the 330C mutation produced melting temperatures, TM, of 69.3 and 68.9 °C, respectfully, whereas the two additional point mutations to enhance the interaction was considerably reduced, TM = 51.7 °C. The latter is surprising. The TM of the CD16V with the Cys mutation (I106C) was 56.0 °C. Both isolated disulfide complexes showed a higher melting temperature. The TM of Fc only and the 330C mutation disulfide bridged to CD 16V with the Cys mutation was 72.8 °C or approximately 4 degrees higher than the highest individual TMS. The TM of FC only and the 330C mutation and additional point mutations disulfide bridged to CD16V with the Cys mutation was 71 °C or approximately 15 degrees higher than the highest individual Tm (here CD 16). These results are consistent with the high binding affinity of the “2X” mutant.

[0024] FIGS. 7A-7E show Fc receptor (FcyRIIIA-CD16) binding of polypeptides including an Fc domain provided herein. The affinity of the different Fc modifications were characaterized by SPR>. The “2X” variant bound with a higher affinity as expected. Here, we expected that the disulfide complex would completely vitiate FcgRIIIA binding (FIGS. 7D-7E). While the SPR traces show- binding, there is a significant drop in the intensity' - consistent with complex not binding. We attribute the remaining binding to presence of additional, non-complexed Fc. No complex formed between h!gGl-Fc2 and CD16aV-His I106C without A330C mutation. No significant binding between CD16aV -His I106C and hFcyRIIIA was detected. FIG. 7A: hlgGl-Fc2 alone. FIG. 7B: MgGl-Fc2 A330C alone. FIG. 7C: h!gGl-Fc2-2X A330C alone. FIG. 7D: h!gGl-Fc2 A330 complexed with CD16aV-His I106C. FIG. 7D: h!gGl-Fc2-2X A330 complexed with CD16aV-His I106C.

[0025] FIG. 8 shows schematics of exemplary bispecific polypeptides described herein. In embodiments, the scFv can be an anti-CD3 scFv, an anti-peptide scFv (e.g., D amino acid peptide with a DOTA for pretargeted imaging / therapy), or a co-expressed target.

[0026] FIGS. 9A-9D show production and SEC purification of an an exemplary polypeptide (e.g., H26H8 A330C) and covalent complex (e.g., mabpack05). FIG. 9A: H26H8 A330C (e.g., aCD3 antigen binding domain) expressed alone (expected size: 150 kDA). FIG.9B: ILlRapH24-CD16aC expressed alone (expected size: 50 kDa). FIG.9C: H26H8 A330C co-expressed with ILlRapH24-CD16aC at 1:2 ratio (expected size: 200 kDa). FIG. 9D: SDS-PAGE gel of fractions from SEC purification.

[0027] FIG. 10 shows the H26H8 A330C / ILlRapH24-CD16aC complex did not interfere with the CD3 binding of a CD3 antigen domain (H26H8) on Jurkat cells.

[0028] FIGS. 11 show production and SEC purification of an exemplary polypeptide (e.g., ILlRapH24 A330C) and covalent complex described herein (e.g., mabpack04).

[0029] FIGS. 12A-12D show production and SEC purification of an exemplary polypeptide (e.g., meTras I83E A330C ) and covalent complex described herein (e.g., mabpackl 1). FIG. 12A: meTras I83E A330C (e.g., aHer2 antigen binding domain) expressed alone (expected size: 150 kDA). FIG. 12B: CD3sp34-CD16aC expressed alone (expected size: 50 kDa). FIG. 12C: meTras I83E A300C co-expressed with CD3sp34-CD16aC at 1:2 ratio (expected size: 200 kDa).FIG. 12D: SDS-PAGE gel of fractions from SEC purification.

[0030] FIGS. 13A-13D show Fc Receptor (FcyRIIIA-CD16) binding of an exemplary polypeptide (e.g., meTras I83E A330C) and covalent complex described herein (e.g., mabpackl 1). FIG. 13A: meTras 183 A330C alone. FIG. 13B: meTras I83E A330C / CD3sp34-CD16aC (e.g., mabpack 11). FIG. 13C: CD3sp34-CD16aC alone. FIG. 13D: No significant binding of FcSTR IgG to hFcyRIIIA was observed.

[0031] FIGS. 14A-14B show Her2 binding of an exemplar)’ polypeptide (e.g., meTras I83E A330C) and covalent complex described herein (e.g., mabpackll). FIG. 14A: meTras I83E A330C / CD3sp34-CD16aC (e.g., mabpack 11). FIG. 14B: meTras I83E A330C alone.

[0032] FIGS. 15A-15B show CD3 binding of an exemplar}' covalent complex (e.g., mabpack 11) and an CD3 antigen binding domain provided herein (e.g., SP34 Fab). FIG. 15A: meTras I83E A330C / CD3sp34-CD16aC (e.g., mabpack 11). FIG. 15B: SP34 Fab alone.

[0033] FIGS. 16A-16B show the exemplary complex provided herein (e.g., mabpack 11) did not interfere with the Her2 binding of a Her2 antigen binding domain (meTrastuzumab antibody) on BT474 cells.

[0034] FIGS. 17A-17B show the exemplary complex provided herein (e.g., mabpack 11) did not interfere with the CD3 binding of a CD3 antigen binding domain (CD3sp34-CD16aC fusion) on Jurkat cells.

[0035] FIGS. 18A-18D show production and SEC purification of an exemplary polypeptide (e.g., meTras I83E A330C) and covalent complex described herein (e.g., mabpack15). FIG. ISA: meTras T83E A330C (e.g., aHer2 antigen binding domain) expressed alone (expected size: 150 kDA). FIG. 18B: CD3sp34-CD16aC-2 expressed alone (expected size: 50 kDa). FIG. 18C: meTras I83E A330C co-expressed with CD3sp34-CD16aC-2 at 1:2 ratio (expected size: 200 kDa). FIG. 18D: SDS-PAGE gel of fractions from SEC purification.

[0036] FIGS. 19A-19B show the exemplary complex provided herein (e.g., mabpack 15) binding to Her2 on BT474 cells was detected through CD 16 fusion.

[0037] FIGS. 20A-20B show the exemplary complex provided herein (e.g., mabpack 15) binding to Her2 on SKOV3 cells was detected through CD16 fusion.

[0038] FIG. 21 shows Jurkat activation against BT474 cells for exemplary covalent complexes provided herein (e.g., mabpackl 1 and mabpack15).

[0039] FIG. 22 shows Jurkat activation against SKOV3 cells for exemplary covalent complexes provided herein (e.g., mabpackl 1 and mabpack15).

[0040] FIGS. 23A-23D show cell killing with exemplary covalent complex provided herein (e.g., mabpack15).

[0041] FIG. 24 shows IFNg production using an exemplary covalent complex provided herein (e.g., mabpacklS).

[0042] FIGS. 25A-25B show fluorescent dye coupling through spare ‘C’ on an exemplary covalent complex provided herein (e.g., mabpack15). The “spare cysteine is A330C, since the Fc is dimeric the second cysteine remains unpaired. The coupling process did not affect the complex.

[0043] FIG. 26 shows SKOV3 cell binding of an exemplary' covalent complex provided herein (e.g. mabpack15) coupled to Alexa Fluor 488 C5 maleimide via disulfide bond.

[0044] FIGS. 27A-27D show production and SEC purification of an exemplary polypeptide (e.g., ILlRapH24 A330C) and covalent complex described herein (e.g., mabpackl4). FIG.27A:ILlRapH24 A330C (e.g., a ILlRap antigen binding domain) expressed alone (expected size: 150 kDA). FIG. 27B: CD3sp34-CD16aC expressed alone (expected size: 50 kDa). FIG. 27C: ILlRapH24 A330C co-expressed with CD3sp34-CD16aC at 1:2 ratio (expected size: 200 kDa).FIG. 27D: SDS-PAGE gel of fractions from SEC purification.

[0045] FIGS. 28A-28B show the exemplary complex provided herein (e.g., mabpack 14) did not interfere with the CD3 binding of a CD3 antigen binding domain (CDsp34-CD16aC).

[0046] FIGS. 29A-29B show the exemplary complex provided herein (e.g., mabpack 14) did not interfere with the ILlRap binding of a ILlRap antigen binding domain (ILlRapH24 antibody) on THP-1 cells. ILlRapH24 A330C has an intact Fc.

[0047] FIGS. 30A-30B show the exemplary complex provided herein (e.g., mabpack 14) did not interfere with the CD3 binding of a CD3 antigen binding domain (CDsp34-CD16aC fusion) on Jurkat cells.

[0048] FIGS. 31 shows a schematic of an exemplary complex provided herein (e.g., mabpack 14).

[0049] FIGS. 32A-32D show production and SEC purification of an exemplary polypeptide (e.g., ILlRapH24 A330C) and covalent complex described herein (e.g., mabpackl6). FIG.32A:ILlRapH24 A330C (e.g., a ILlRap antigen binding domain) expressed alone (expected size: 150 kDA). FIG. 32B: CD3sp34-CD16aC-2 expressed alone (expected size: 50 kDa). FIG.32C: ILlRapH24 A330C co-expressed with CD3sp34-CD16aC-2 at 1:2 ratio (expected size: 200 kDa). FIG. 32D: SDS-PAGE gel of fractions from SEC purification.

[0050] FIGS. 33 shows ILlRap binding of an exemplary complex provided herein (e.g., mabpack 16).

[0051] FIGS. 34A-34B show the binding of an exemplar}' complex provided herein (e.g., mabpack 16) to ILlRap on Molml3 cells was detected through CD16 fusion.

[0052] FIGs. 35A-35B show the binding of an exemplary complex provided herein (e.g., mabpack 16) to ILlRap on Jurkat cells was detected through CD 16 fusion.

[0053] FIGS. 36A-36D show production and SEC purification of an exemplary polypeptide (e.g., EGFRD4-5C8 A330C) and covalent complex described herein (e.g., mabpack22). FIG. 36A: EGFRD4-5C8 A330C (e.g., a EGFRD4 antigen binding domain) expressed alone (expected size: 150 kDA). FIG. 36B: CD3sp34-CD16aC-2 expressed alone (expected size: 50 kDa). FIG. 36C: EGFRD4-5C8 A330C co-expressed with CD3sp34-CD16aC-2 at 1:2 ratio (expected size: 200 kDa). Complex was purified through His-tag before SEC. FIG. 36D: SDS-PAGE gel of fractions from SEC purification.

[0054] FIGS. 37A-37C show the binding of an exemplary' polynucleotide (e.g., EGFRD4-5C8 A330C) and a covalent complex provided herein (e.g., mabpack22) to EGFR.

[0055] FIGS. 38A-38B show the binding of an exemplary covalent complex provided herein (e.g., mabpack22) to EGFR on MDA-MB-468 cells, SKOV3 cells, and BT474 cells was detected through CD 16 fusion.

[0056] FIGS. 39A-39B show the binding of an exemplary' covalent complex provided herein (e.g., mabpack22) to CD3 on Jurkat cells was detected through parental antibody.

[0057] FIGS. 40A-40C show Jurkat activation against MDA-MB-468 cells (FIG. 40A), SKOV3 cells (FIG. 40B), and BT474 cells (FIG. 40C) for an exemplary covalent complex provided herein (e.g., mabpack22).

[0058] FIG. 41 show SEC purification CD30-33 A330C co-expressed with CD3sp34-CD16aC-2 at 1:2 ratio (expected size: 200 kDa). Complex was purified though His-tag before SEC.

[0059] FIGS. 42A-42E show SPR and cell binding data of exemplary’ covalent complexes provided herein with additional 5 amino acid linker inserted between Fab and Fc to Her2 (FIGS.42A-42B) and ILlRap (FIGS. 42C-42D). FIG.42E: Binding to CD3 on Jurkat cells. No discernable change on target binding from addition of 5 amino acid linker between Fab and Fc.

[0060] FIGS. 43 shows production and purification of CD3scFv (e.g., H26H8)-CD16 fusion optimized polypeptides.

[0061] FIG. 44 shows production and purification of tumor-activated CD3 scFv (e.g., H26H8)-CD 16 fusion.

[0062] FIGS. 45A-45B show production and purification (FIG. 45A) and binding to CD3 on T cells (FIG.45B) of C-terminual scFv-CD16 fusion (e.g., CD16aC-CD3sp34).

[0063] FIGS. 46A-46D shows an exemplary polypeptide provided herein (e.g., Split scFv-CD16 fusion). FIG. 46A: a schematic of an exemplary polypeptide provided herein (e.g., Split scFv-CD16 fusion). As the CD 16 (or other FcgR receptors) have an N and C termini and the domains termini are relatively close in proximity, we can “use” the CD 16 as a “linker” for ”hetero” dimeric proteins. Here, we demonstrate that we can replace the “gly-ser” linker (shown in inset) commonly used in the create of scFvs with the CD 16. Shown here is an atomically ’’correct” model. The cyan and light green ribbons are the variable domains isolated from the 4ioi structure and manually placed next to the N- and C-termini of the CD16. FIG.46B-46C:Production and SEC purification of CD3sp34-CD16aC-LH (FIG.46B) and CD3sp34-CD16aC-HL (FIG. 46C). FIG. 46D: Split scFv-CD16 binding to CD3 on T cell.

[0064] FIGS. 47A-47F show production and purification of an exemplary cytokine fusion polypeptide provided herein (e.g., mabpack26). FIG. 47A: Schematic of a cytokine fusion polypeptide provided herein. FIG.47B: meTras I83E A330C (e.g., aHer2 antigen binding domain) expressed alone (expected size: 150 kDA). FIG.48C: maskedIL2-CD16aC expressed alone (expected size: 70 kDa). FIG. 47D: meTras I83E A330C co-expressed with maskedIL2-CD16aC at 1:2 ratio (expected size: 220 kDa). Complex was purified through His-tag before SEC. FIG. 47E: SDS-PAGE gel of fractions from SEC purification. FIG. 47F: SDS-PAGE gel showing MMP7 cleaved mabpack26.

[0065] FIGS. 48A-48B show data from an exemplary polypeptide provided herein including a CD 16 domain, an IL2 receptor domain, and a tumor-activated masked IL2 domain.

[0066] FIGS. 49A-49E show an exemplary single chain polypeptide (e.g., a bivalent binder also referred to herein as bionic, which may include a Fab domain and a nanobody domain) attached to a CD 16 domain, which is attached through disulfide linkage to an Fc domain thereby extending the lifetime of the single chain polypeptide. FIG.49A: A schematic of an exemplary polypeptide provided herein (e.g., mabpack41). A common means of increasing the lifetime of a biologic is to add an Fc domain (other approaches including adding an albumin binding domain (peptide or nanobody), PEGylation, PASylation, etc.). We demonstrate herein we can simplyfuse the biologic of interest to CD16 and co-express the A330C Fc. FIGS. 49B-49D: Production and SEC purification of exemplary' polypeptides (e.g. hlgGl-Fc A330C and BN02-CD16aC) and a covalent complex provided herein (e.g., mabpack41). FIG. 49B: hlgGl-Fc A330C expressed alone (expected size: 50 kDA). FIG. 49C: BN02-CD16aC expressed alone (expected size: 85 kDa). FIG. 49D: hlgGl-Fc A330C co-expressed with BN02-CD16aC at 1:1 ratio (expected size: 135 kDa). FIG. 49E: BN02-CD16aC fusion binding to CD3 on T cells.

[0067] FIG. 50 shows data from a T cell activation assay using an exemplary' polypeptide provided herein (e.g., mabpack 43). The mabpack 43 polypeptide (meTras I83E A330C / masked IL2-CD16aC-2, split masked IL-2) is effective at activating T cells (e.g., NK cells, CD4+ / pSTAT5+cells, and CD8+ / pSTAT5+cells.

[0068] FIGS. 51 A-51B show sequence information for canonical immunoglobulin G (IgG) molecules. FIG. 51A: Sequence information for IGHG1, which is chosen as the canonical sequence. FIG. 51B: Sequence alignment of canonical IgG Fc regions. Shadded residues indicate positions for cysteine substitutions.

[0069] FIG. 52 shows a sequence alignment of CD16a and CD16b. Individual shadded residues indicate positions for cysteine substitutions.

[0070] FIG. 53 shows a sequence alignment for canonical CD16a proteins.

[0071] FIG. 54 show cysteine binding pair positions in CD16 (C chain) Fc (A chain) complex.

[0072] FIG. 55 shows cysteine binding pair positions in CD32B (C chain) Fc (A chain) complex.

[0073] FIG. 56 shows sequence information for CD16-I.

[0074] FIG. 57 shows the structural and sequence information for CD32.

[0075] FIG. 58 shows the structure of CD32B bound to an Fc region and the cysteine binding pair positions in CD32B (C chain) Fc (A chain) complex.

[0076] FIG. 59 shows the structure of CD32B bound to an Fc region and the cysteine binding pair positions in CD32B (C chain) Fc (B chain) complex.

[0077] FIG. 60 shows a sequence alignment of CD32B isoforms.

[0078] FIG. 61 shows sequence information for CD64.

[0079] FIGS. 62A-62B show the structure of CD64 bound to an FC region and the cysteine binding pair positions in CD64 (A chain) Fc (J chain) complex.

[0080] FIG. 63 shows sequence information for CD64.

[0081] FIG. 64 shows a sequence alignment. A blast of PDB also afforded 8DIN.

[0082] FIG. 65: The figure shows a schematic drawing of an exemplary conjugate provided herein.

[0083] FIG. 66: The figure shows schematic drawings of exemplary conjugates provided herein.

[0084] FIG. 67: The figure shows positions amenable to building disulfide bonds between sushi and IL15, including residue 67 on sushi to residue 90 on IL15 and residue 67 on sushi to residue 87 on IL 15.

[0085] FIG. 68: The figure shows that the positions for building disulfide bonds are remote from the receptor site.

[0086] FIG. 69: The figure provides a visual summary of second ligand binding domains and second ligand binding domain enhancers useful for the complexes and methods provided herein.

[0087] FIGS. 70A-70E: The figures show SDS-PAGE analysis of protease cleavage of exemplary conjugates provided herein.

[0088] FIG. 71: The figure shows cell binding depicting binding of exemplary conjugates provided herein.

[0089] FIG. 72A-72C: The figure shows exemplary representations of polypeptides including a cytokine domain, a cytokine receptor domain and / or a cytokine enhancer domain.

[0090] FIG. 73: Cell lysis by T cells using different versions of aHer2 TCE - in all cases, the mAb is trastuzumab. In mabpack15 - the sp34 scfv is fused to the N-terminus of the cys-CD16. In mabpack33, the scFv is fused to the C-terminus of cys-CD16. In mabpack31 and 32 replace the gly-ser linker used to create an scFv (e.g., joining the C-terminus of the variable heavydomain to the N-terminus of the variable light chain domain or vice versa) with the CD 16. CD 16 domain replaces the gly-ser linker connecting the the C-terminus of the variable heavy domain to the N-terminus of the variable light chain domain and vice versa. Mabpack37 is the cys-CD16 with no extension and serves as a control. Real time cell analysis is used to characterize the lysis of SKOV-GPF cells in the presence of T cells at different mabpack concentrations over time (each trace is cell viability). No cell killing is observed for the control (mabpack 37), the other configurations show potent killing but with slightly different EC50s.

[0091] FIG. 74: Data extracted from FIG.73. Cell viability at 72 hours (normalized cell index) is plotted against the concentration of each Mabpack.

[0092] FIG. 75: Cartoon of exemplary polypeptides provided herein. Two anti-CD3 scFvs (mabpack46) or one anti-CD28 scFv and one anti-CD3 sfv (mabpack47) may be assembled.

[0093] FIG. 76: Depicts Size exclusion chromatography of exemplary polypeptides provided herein.

[0094] FIG. 77: Real time cell analysis is used to characterize the lysis of SKOV-GPF cells in the presence of T cells at different mabpack concentrations over time (each trace is cell viability). No cell killing is observed for the control (mabpack 37), the other configurations show potent killing.

[0095] FIG. 78: Data extracted from FIG.77. Cell viability at 72 hours (normalized cell index) is plotted against the concentration of each Mabpack.

[0096] FIG. 79: Size exclusion chromatography shows produced mabpack26 a symmetric peak. Production and purification: mabpack26 (meTras I83E A330C / maskedIL2-CD16aC).

[0097] FIG. 80: Depicts protease cleavage: mabpack26. MaskedIL2-CD16aC on mabpack26 cleaved by mmp7.

[0098] FIG. 81: Detection of STAT5 phosphorylation in CD8-positive and CD4-positive T cells and CD56-positive NK cells from human PBMCs (M46) with mabpack26, IL2 and anti-Her2 antibody. Mabpack26 showed the significantly reduced IL2 engaged STAT5 phosphorylation on these cells.

[0099] FIG. 82: Depicts Protease cleavage: mabpack43. MaskedIL2-CD16aC-2 on mabpack43 cleaved by mmp7.

[0100] FIG. 83: Detection of STAT5 phosphorylation in CD8-positive and CD4-positive T cells and CD56-positive NK cells from human PBMCs (M46) with mabpack26, mabpack43, IL2 and anti-Her2 antibody. Mabpack43 showed an additional reduction of IL2 engaged STAT5 phosphorylation on these cells comparing to mabpack26.

[0101] FIG. 84: Protease-dependent T cell activation. Detection of STAT5 phosphorylation in CD8-positive and CD4-positive T cells and CD56-positiveNK cells from human PBMCs (M46) with IL2 and mabpack43 with / without mmp7 treatment. Without mmp7 treatment (null), mabpack43 showed the significantly reduced IL2 engaged STAT5 phosphorylation on these cells. However, with mmp7 treated mabpack43 (mmp7) restored IL2 engaged STAT5 phosphorylation.

[0102] FIG. 85: Size exclusion chromatography shows produced mabpack42 and mabpack54. Only symmetric peaks were collected for each.

[0103] FIG. 86: Size exclusion chromatography shows produced mabpack58 a symmetric peak.

[0104] FIG. 87: Size exclusion chromatography shows produced mabpack82, mabpack83, mabpack86 and mabpack82. Only symmetric peaks were collected for each.

[0105] FIG. 88: Free cysteine on one of the Fc chains, was chemically capped with iodoacetamide. Left graph. The free thiol quantification kit was used to measure free cysteines. The mabpack (aher2-acd3) indicated 0.4 molar ratio. Anti-Her2 only (parental) indicated no free cysteines, The a330c aher2 (no CD16 conjugation) show ~ 0.8. Compared to the complex (mabpack), roughly twice the number as expected. The right panel shows the free thiols after capping them with iodoacetamide. Critically the reduced and capped complex indicate minimal to zero free thiols, similar to the control (parental aHer2), indicating successful capping or eliminating of a second disulfide.

[0106] FIG. 89: SDS-PAGE indicates the iodoacetamide treatment left the complex intact.

[0107] FIG. 90: Fc is dimeric and there are two cysteines compared to one cysteine on the fcgR (cdl6). A second point mutation in the CD16 was introduced such that it could generate a second disulfide to the “free cys” on the second. There were still free cys observed on the complex with these pairs of cys mutations.

[0108] FIG. 91: Fc is dimeric and there are two cysteines compared to one cysteine on the fcgR (cdl 6). A second point mutation in the CD16 was introduced such that it could generate a second disulfide to the “free cys” on the second.

[0109] FIG. 92: The complex is stable over 168 hours in mouse serum at 37 °C.

[0110] FIG. 93: Mabpack44 is a complex with asymmetric IgG with enhanced CD 16 binding, and a single Cys which can be paired with single Cys on aCD3-CD16 fusion. Size exclusion chromatography shows produced mabpack44 and it failed to bind CD3 on Jurkat cells.

[0111] FIG. 94: Production and purification: mabpack41 (hIgGl-Fc2 A330C / BN02-CD16aC). Size exclusion chromatography shows produced mabpack41 a symmetric peak.

[0112] FIG. 95: CD3-CD38 Bionic-CD16 fusion binding to CD3 on T cell *PanT cells: prepared from PBMC (healthy donor, M46) using Pan T cell isolation kit (Miltenyi 130-096-535) Secondary Ab: HisAF488 (Mouse anti-His Tag Antibody, Alexa Fluor® 488, BioLegend # 652509).

[0113] FIG. 96: Real time cell analysis is used to characterize the lysis of SKOV-GPF cells in the presence of T cells at different mabpack concentrations over time (each trace is cell viability).

[0114] FIG. 97: Data extracted from FIG. 96. Cell viability at 72 hours (normalized cell index) is plotted against the concentration of each Mabpack.

[0115] FIG. 98: SKOV3 (Her2+, CDH6+), T cell engaged cell killing. Synergistic killing of SKOV3 cells mediated by combinations of aCDH6-aCD3 (10 pM) with either aHer2-IL2 (100 pM) or aHer2-aCD28 (100 pM) in the presence of T cells at a 10:1 E: T ratio. For comparison, SKOV3 cell killing mediated by the combination of aCDH6-aCD3 (10 pM) and aHer2-aCD3v2 (10 pM) is shown.

[0116] FIG. 99: T cell engaged SKOV3 killing: comparison FcRn enhanced mutation.

[0117] FIG. 100: Real time cell analysis is used to characterize the lysis of SKOV-GPF cells in the presence of T cells at different mabpack concentrations over time (each trace is cell viability').

[0118] FIG. 101: mabpackl07, -108, -109 binding to Her2 on SPR.

[0119] FIG. 102: mabpackl07, -108, -109 binding to CD3 on SPRDETAILED DESCRIPTION

[0120] While various embodiments and aspects of the present invention are shown and described herein, it will be obvious to those skilled in the art that such embodiments and aspects are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention.

[0121] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. All documents, or portions of documents, cited in the application including, without limitation, patents, patent applications, articles, books, manuals, and treatises are hereby expressly incorporated by reference in their entirety for any purpose.DEFINITIONS

[0122] The abbreviations used herein have their conventional meaning within the chemical and biological arts. The chemical structures and formulae set forth herein are constructed according to the standard rules of chemical valency known in the chemical arts.

[0123] As used herein, the term "about" means a range of values including the specified value, which a person of ordinary skill in the art would consider reasonably similar to the specified value. In embodiments, the term "about" means within a standard deviation using measurements generally acceptable in the art. In embodiments, about means a range extending to + / - 10% of the specified value. In embodiments, about means the specified value.

[0124] The terms "a" or "an," as used in herein means one or more. In addition, the phrase "substituted with a[n]," as used herein, means the specified group may be substituted with one or more of any or all of the named substituents. For example, where a group, such as an alkyl or heteroaryl group, is "substituted with an unsubstituted C1-C20 alkyl, or unsubstituted 2 to 20 membered heteroalkyl," the group may contain one or more unsubstituted C1-C20 alkyls, and / or one or more unsubstituted 2 to 20 membered heteroalkyls. Moreover, where a moiety is substituted with an R substituent, the group may be referred to as “R-substituted.” Where a moiety is R-substituted, the moiety is substituted with at least one R substituent and each R substituent is optionally different.

[0125] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art. See, e.g., Singleton et al., DICTIONARY OF MICROBIOLOGY AND MOLECULAR BIOLOGY 2nd ed., J. Wiley & Sons (New York. NY 1994); Sambrook et al., MOLECULAR CLONING, A LABORATORY MANUAL, Cold Springs Harbor Press (Cold Springs Harbor, NY 1989). Any methods, devices and materials similar or equivalent to those described herein can be used in the practice of this invention. The following definitions are provided to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.

[0126] " Nucleic acid" refers to deoxyribonucleotides or ribonucleotides and polymers thereof in either single- or double-stranded form, and complements thereof. The term "polynucleotide" refers to a linear sequence of nucleotides. The term "nucleotide" typically refers to a single unit of a polynucleotide, i.e., a monomer. Nucleotides can be ribonucleotides, deoxyribonucleotides, or modified versions thereof. Examples of polynucleotides contemplated herein include single and double stranded DNA. single and double stranded RNA (including siRNA), and hybrid molecules having mixtures of single and double stranded DNA and RNA. Nucleic acid as used herein also refers to nucleic acids that have the same basic chemical structure as a naturally occurring nucleic acid. Such analogues have modified sugars and / or modified ring substituents, but retain the same basic chemical structure as the naturally occurring nucleic acid. A nucleic acid mimetic refers to chemical compounds that have a structure that is different the general chemical structure of a nucleic acid, but that functions in a manner similar to a naturally occurring nucleic acid. Examples of such analogues include, without limitation,phosphorothioates, phosphorami dates, methyl phosphonates, chiral-methyl phosphonates, 2-0-methyl ribonucleotides, and peptide-nucleic acids (PNAs).

[0127] The term “amino acid” refers to naturally occurring and synthetic amino acids, as well as amino acid analogs and amino acid mimetics that function in a manner similar to the naturally occurring amino acids. Naturally occurring amino acids are those encoded by the genetic code, as well as those amino acids that are later modified, e.g., hydroxyproline, y-carboxy glutamate, and O-phosphoserine. Amino acid analogs refers to compounds that have the same basic chemical structure as a naturally occurring amino acid, i.e., an a carbon that is bound to a hydrogen, a carboxyl group, an amino group, and an R group, e.g., homoserine, norleucine, methionine sulfoxide, methionine methyl sulfonium. Such analogs have modified R groups (e.g., norleucine) or modified peptide backbones, but retain the same basic chemical structure as a naturally occurring amino acid. Amino acid mimetics refers to chemical compounds that have a structure that is different from the general chemical structure of an amino acid, but that functions in a manner similar to a naturally occurring amino acid.

[0128] Amino acids may be referred to herein by either their commonly known three letter symbols or by the one-letter symbols recommended by the IUPAC-IUB Biochemical Nomenclature Commission. Nucleotides, likewise, may be referred to by their commonly accepted single-letter codes.

[0129] The terms “polypeptide,” “peptide” and “protein” are used interchangeably herein to refer to a polymer of amino acid residues. The terms apply to amino acid polymers in which one or more amino acid residue is an artificial chemical mimetic of a corresponding naturally occurring amino acid, as well as to naturally occurring amino acid polymers and non-naturally occurring amino acid polymer.

[0130] An amino acid or nucleotide base "position" is denoted by a number that sequentially identifies each amino acid (or nucleotide base) in the reference sequence based on its position relative to the N-terminus (or 5'-end). Due to deletions, insertions, truncations, fusions, and the like that may be taken into account when determining an optimal alignment, in general the amino acid residue number in a test sequence determined by simply counting from the N-terminus will not necessarily be the same as the number of its corresponding position in the referencesequence. For example, in a case where a variant has a deletion relative to an aligned reference sequence, there will be no amino acid in the variant that corresponds to a position in the reference sequence at the site of deletion. Where there is an insertion in an aligned reference sequence, that insertion will not correspond to a numbered amino acid position in the reference sequence. In the case of truncations or fusions there can be stretches of amino acids in either the reference or aligned sequence that do not correspond to any amino acid in the corresponding sequence.

[0131] The terms "corresponding to" or "numbered with reference to," when used in the context of the numbering of a given amino acid or polynucleotide sequence, refers to the numbering of the residues of a specified reference sequence when the given amino acid or polynucleotide sequence is compared to the reference sequence. An amino acid residue in a protein "corresponds" to a given residue when it occupies the same essential structural position within the protein as the given residue. For example, the position of a selected residue (e.g., a cysteine) in an Fc receptor domain or an Fc domain corresponds, for example, to the amino acid position 106 of a reference protein, (e.g., CD16), when the selected residue occupies the same essential spatial or structural position as the amino acid at position 106 of the reference protein (e.g., CD16). In some embodiments, where a selected protein is aligned for maximum homology with the reference protein (e.g., CD 16) the position in the aligned selected protein aligning with the amino acid at position 106 is said to correspond to amino acid position 106. Instead of a primary sequence alignment, a three dimensional structural alignment can also be used, e.g., where the structure of the selected protein (e.g., a pdb structure as provided herein) is aligned for maximum correspondence with the reference protein at, for example, position 106, and the overall structures compared. In this case, an amino acid that occupies the same essential position as the amino acid at position 106 in the structural model is said to correspond to the amino acid at position 106.

[0132] Likewise, a selected residue in a selected protein or protein domain (e.g., an Fc gamma domain, a cytokine domain) corresponds, for example, to a residue at position 106, when the selected residue occupies the same essential spatial or other structural position within the protein or protein domain as the residue at position 106. In some embodiments, where a selected protein or protein domain is aligned for maximum homology with, the position in the aligned selectedprotein or protein domain aligning with position 106 is said to correspond to position 106. Instead of a primary sequence alignment, a three dimensional structural alignment can also be used, e.g., where the structure of the selected protein or protein domain is aligned for maximum correspondence with the residue at position 106. and the overall structures compared. In this case, an amino acid that occupies the same essential position as residue 106 in the structural model is said to correspond to the 106 residue. The position corresponding to the residue at position 106 in the amino acid sequence of CD16 (e.g., SEQ ID NO:4 or SEQ ID NO:5) as provided herein may be position 88 in the structural model (e.g., pdb).

[0133] For CD 16 provided herein including embodiments thereof, the amino acid positions contemplated for cysteine substitutions may include, for example, 106, 134, 137, 176, 131, 178, and 179. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 106 is position 88. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 131 is position 113. In embomdiments. the position occupied by the amino acid corresponding to amino acid position 134 is position 116. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 178 is position 160.

[0134] For CD32 provided herein including embodiments thereof, the amino acid positions contemplated for cysteine substitutions include, for example, 121. 146, 194, 162, and 167. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 121 is position 85. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 146 is position 110. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 194 is position 158. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 162 is position 126. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 167 is position 131.

[0135] For CD64 provided herein including embodiments thereof, the amino acid positions contemplated for cysteine substitutions include, for example, 102. 130, 173, 174, 143, 146, 148 and 134.

[0136] For the Fc domain provided herein including embodiments thereof, the amino acid positions contemplated for cysteine substitutions include, for example, 213, 261, 212, 260, 118, 119, 120, 121, 181, 150, 182, and 148. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 213 is position 330. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 261 is position 330. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 212 is position 329. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 260 is position 329. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 118 is position 235. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 119 is position 236. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 120 is position 237. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 121 is position 238. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 181 is position 298. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 150 is position 267. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 182 is position 299. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 150 is position 267. In embomdiments, the position occupied by the amino acid corresponding to amino acid position 148 is position 265.

[0137] " Conservatively modified variants" applies to both amino acid and nucleic acid sequences. With respect to particular nucleic acid sequences, "conservatively modified variants" refers to those nucleic acids that encode identical or essentially identical amino acid sequences. Because of the degeneracy of the genetic code, a number of nucleic acid sequences will encode any given protein. For instance, the codons GCA, GCC, GCG and GCU all encode the amino acid alanine. Thus, at every position where an alanine is specified by a codon, the codon can be altered to any of the corresponding codons described without altering the encoded polypeptide. Such nucleic acid variations are "silent variations." which are one species of conservatively modified variations. Every nucleic acid sequence herein which encodes a polypeptide also describes every possible silent variation of the nucleic acid. One of skill will recognize that each codon in a nucleic acid (except AUG, which is ordinarily the only codon for methionine, andTGG, which is ordinarily the only codon for tryptophan) can be modified to yield a functionally identical molecule. Accordingly, each silent variation of a nucleic acid which encodes a polypeptide is implicit in each described sequence.

[0138] As to amino acid sequences, one of skill will recognize that individual substitutions, deletions or additions to a nucleic acid, peptide, polypeptide, or protein sequence which alters, adds or deletes a single amino acid or a small percentage of amino acids in the encoded sequence is a "conservatively modified variant" where the alteration results in the substitution of an amino acid with a chemically similar amino acid. Conservative substitution tables providing functionally similar amino acids are well known in the art. Such conservatively modified variants are in addition to and do not exclude polymorphic variants, interspecies homologs, and alleles of the invention.

[0139] The following eight groups each contain amino acids that are conservative substitutions for one another:1) Alanine (A), Glycine (G);2) Aspartic acid (D), Glutamic acid (E);3) Asparagine (N), Glutamine (Q);4) Arginine (R), Lysine (K);5) Isoleucine (I), Leucine (L), Methionine (M), Valine (V);6) Phenylalanine (F), Tyrosine (Y), Tryptophan (W);7) Serine (S), Threonine (T); and8) Cysteine (C), Methionine (M)(see, e.g., Creighton, Proteins (1984)).

[0140] The terms "identical" or percent "identity," in the context of two or more nucleic acids or polypeptide sequences, refer to two or more sequences or subsequences that are the same or have a specified percentage of amino acid residues or nucleotides that are the same (i.e., 60% identity, optionally 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99% identity over aspecified region, e.g., of the entire polypeptide sequences of the invention or individual domains of the polypeptides of the invention), when compared and aligned for maximum correspondence over a comparison window, or designated region as measured using one of the following sequence comparison algorithms or by manual alignment and visual inspection. Such sequences are then said to be "substantially identical." This definition also refers to the complement of a test sequence. Optionally, the identity exists over a region that is at least about 50 nucleotides in length, or more preferably over a region that is 100 to 500 or 1000 or more nucleotides in length.

[0141] " Percentage of sequence identity" is determined by comparing two optimally aligned sequences over a comparison window, wherein the portion of the polynucleotide or polypeptide sequence in the comparison window may comprise additions or deletions (i.e., gaps) as compared to the reference sequence (which does not comprise additions or deletions) for optimal alignment of the two sequences. The percentage is calculated by determining the number of positions at which the identical nucleic acid base or amino acid residue occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the window of comparison and multiplying the result by 100 to yield the percentage of sequence identity.

[0142] For sequence comparison, typically one sequence acts as a reference sequence, to which test sequences are compared. When using a sequence comparison algorithm, test and reference sequences are entered into a computer, subsequence coordinates are designated, if necessary, and sequence algorithm program parameters are designated. Default program parameters can be used, or alternative parameters can be designated. The sequence comparison algorithm then calculates the percent sequence identities for the test sequences relative to the reference sequence, based on the program parameters.

[0143] A "comparison window", as used herein, includes reference to a segment of any one of the number of contiguous positions selected from the group consisting of, e.g., a full length sequence or from 20 to 600, about 50 to about 200, or about 100 to about 150 amino acids or nucleotides in which a sequence may be compared to a reference sequence of the same number of contiguous positions after the two sequences are optimally aligned. Methods of alignment of sequences for comparison are well-known in the art. Optimal alignment of sequences for comparison can be conducted, e.g., by the local homology algorithm of Smith and Waterman(1970) Adv. Appl. Math. 2:482c, by the homology alignment algorithm of Needleman and Wunsch (1970) J. Mol. Biol. 48:443, by the search for similarity method of Pearson and Lipman (1988) Proc. Nat’l. Acad. Sci. USA 85:2444, by computerized implementations of these algorithms (GAP, BESTFIT. FASTA, and TFASTA in the Wisconsin Genetics Software Package, Genetics Computer Group, 575 Science Dr., Madison, WI), or by manual alignment and visual inspection (see, e.g., Ausubel et al., Current Protocols in Molecular Biology (1995 supplement)).

[0144] An example of an algorithm that is suitable for determining percent sequence identity and sequence similarity are the BLAST and BLAST 2.0 algorithms, which are described in Altschul et al. (1977) Nuc. Acids Res. 25:3389-3402, and Altschul et al. (1990) J. Mol. Biol. 215:403-410, respectively. Software for performing BLAST analyses is publicly available through the National Center for Biotechnology Information (http: / / www.ncbi.nlm.nih.gov / ). This algorithm involves first identifying high scoring sequence pairs (HSPs) by identifying short words of length W in the query sequence, which either match or satisfy some positive-valued threshold score T when aligned with a word of the same length in a database sequence. T is referred to as the neighborhood word score threshold (Altschul et al., supra). These initial neighborhood word hits act as seeds for initiating searches to find longer HSPs containing them. The word hits are extended in both directions along each sequence for as far as the cumulative alignment score can be increased. Cumulative scores are calculated using, for nucleotide sequences, the parameters M (reward score for a pair of matching residues; always > 0) and N (penalty score for mismatching residues; always < 0). For amino acid sequences, a scoring matrix is used to calculate the cumulative score. Extension of the word hits in each direction are halted when: the cumulative alignment score falls off by the quantity X from its maximum achieved value; the cumulative score goes to zero or below, due to the accumulation of one or more negative-scoring residue alignments; or the end of either sequence is reached. The BLAST algorithm parameters W, T, and X determine the sensitivity and speed of the alignment. The BLASTN program (for nucleotide sequences) uses as defaults a word length (W) of 11, an expectation (E) or 10, M=5, N=-4 and a comparison of both strands. For amino acid sequences, the BLASTP program uses as defaults a word length of 3, and expectation (E) of 10, and the BLOSUM62 scoring matrix (see Henikoff and Henikoff (1989) Proc. Natl. Acad. Sci. USA89:10915) alignments (B) of 50, expectation (E) of 10, M=5, N=-4, and a comparison of both strands.

[0145] The BLAST algorithm also performs a statistical analysis of the similarity between two sequences (see, e.g., Karlin and Altschul (1993) Proc. Natl. Acad. Sci. USA 90:5873-5787). One measure of similarity provided by the BLAST algorithm is the smallest sum probability (P(N)), which provides an indication of the probability by which a match between two nucleotide or amino acid sequences would occur by chance. For example, a nucleic acid is considered similar to a reference sequence if the smallest sum probability in a comparison of the test nucleic acid to the reference nucleic acid is less than about 0.2, more preferably less than about 0.01. and most preferably less than about 0.001.

[0146] An indication that two nucleic acid sequences or polypeptides are substantially identical is that the polypeptide encoded by the first nucleic acid is immunologically cross reactive with the antibodies raised against the polypeptide encoded by the second nucleic acid, as described below. Thus, a polypeptide is typically substantially identical to a second polypeptide, for example, where the two peptides differ only by conservative substitutions. Another indication that two nucleic acid sequences are substantially identical is that the two molecules or their complements hybridize to each other under stringent conditions, as described below. Yet another indication that two nucleic acid sequences are substantially identical is that the same primers can be used to amplify the sequence.

[0147] Antibodies are large, complex molecules (molecular weight of ~150,000 or about 1320 amino acids) with intricate internal structure. A natural antibody molecule contains two identical pairs of polypeptide chains, each pair having one light chain and one heavy chain. Each light chain and heavy chain in turn consists of two regions: a variable (“V”) region, involved in binding the target antigen, and a constant (“C”) region that interacts with other components of the immune system. The light and heavy chain variable regions (also referred to herein as light chain variable (VL) domain and heavy chain variable (VH) domain, respectively) come together in 3-dimensional space to form a variable region that binds the antigen (for example, a receptor on the surface of a cell). Within each light or heavy chain variable region, there are three short segments (averaging 10 amino acids in length) called the complementarity determining regions (“CDRs”). The six CDRs in an antibody variable domain (three from the light chain and threefrom the heavy chain) fold up together in 3-dimensional space to form the actual antibody binding site which docks onto the target antigen. The position and length of the CDRs have been precisely defined by Kabat, E. et al., Sequences of Proteins of Immunological Interest, U. S. Department of Health and Human Services, 1983, 1987. The part of a variable region not contained in the CDRs is called the framework (" FR"), which forms the environment for the CDRs.

[0148] The terms " CDR LI", " CDR L2" and " CDR L3" as provided herein refer to the complementarity determining regions (CDR) 1, 2, and 3 of the variable light (L) chain of an antibody. In embodiments, the variable light chain provided herein includes in N-terminal to C-terminal direction a CDR LI, a CDR L2 and a CDR L3. Likewise, the terms " CDR Hl", " CDR H2" and " CDR H3" as provided herein refer to the complementarity determining regions (CDR) 1, 2, and 3 of the variable heavy (H) chain of an antibody. In embodiments, the variable heavy chain provided herein includes in N-terminal to C-terminal direction a CDR Hl, a CDR H2 and a CDR H3.

[0149] " Framework regions" (FRs) are those variable region residues other than the CDR residues. The FRs of VH are also referred to herein as FR Hl, FR H2, FR H3 and FR H4, respectively, wherein FR Hl corresponds to FR 1 of VH, FR H2 corresponds to FR 2 of VH, FR H3 corresponds to FR 3 of VH and FR H4 corresponds to FR 4 of VH. Likewise, the FRs of the variable region of the heavy chain are further referred to herein as HFRL HFR2, HFR3 and HFR4, respectively, wherein HFR1 corresponds to FR 1 of VH, HFR 2 corresponds to FR 2 of VH, HFR 3 corresponds to FR 3 of VH and HFR 4 corresponds to FR 4 of VH. Likewise, the FRs of VL are referred to herein as FR LI, FR L2. FR L3 and FR L4, respectively, wherein FR LI corresponds to FR 1 of VL. FR L2 corresponds to FR 2 of VL, FR L3 corresponds to FR 3 of VL and FR L4 corresponds to FR 4 of VL. Likewise, the FRs of the variable region of the light chain are further referred to herein as LFR1, LFR2, LFR3 and LFR4, respectively, wherein LFR1 corresponds to FR 1 of VL, LFR 2 corresponds to FR 2 of VL, LFR 3 corresponds to FR 3 of VL and LFR 4 corresponds to FR 4 of VL.

[0150] An exemplars’ immunoglobulin (antibody) structural unit comprises a tetramer. Each tetramer is composed of two identical pairs of polypeptide chains, each pair having one “light” (about 25 kD) and one “heavy” chain (about 50-70 kD). The N-terminus of each chain defines avariable region of about 100 to 110 or more amino acids primarily responsible for antigen recognition. The terms variable light chain (VL), variable light chain (VL) domain or light chain variable region and variable heavy chain (VH), variable heavy chain (VH) domain or heavy chain variable region refer to these light and heavy chain regions, respectively. The terms variable light chain (VL), variable light chain (VL) domain and light chain variable region as referred to herein may be used interchangeably. The terms variable heavy chain (VH), variable heavy chain (VH) domain and heavy chain variable region as referred to herein may be used interchangeably. The Fc (i.e. fragment crystallizable region) is the "base" or "tail" of an immunoglobulin and is typically composed of two heavy chains that contribute two or three constant domains depending on the class of the antibody. By binding to specific proteins, the Fc region ensures that each antibody generates an appropriate immune response for a given antigen. The Fc region also binds to various cell receptors, such as Fc receptors, and other immune molecules, such as complement proteins.

[0151] The term "antibody" is used according to its commonly known meaning in the art. Antibodies exist, e.g., as intact immunoglobulins or as a number of well-characterized antibody fragments produced by digestion with various peptidases. Thus, for example, pepsin digests an antibody below the disulfide linkages in the hinge region to produce F(ab)'2, a dimer of Fab which itself is a light chain joined to VH-CHI by a disulfide bond. The F(ab)'2 may be reduced under mild conditions to break the disulfide linkage in the hinge region, thereby converting the F(ab)'2 dimer into an Fab' monomer. The Fab' monomer is essentially Fab with part of the hinge region (see Fundamental Immunology (Paul ed., 3d ed. 1993). While various antibody¬ fragments are defined in terms of the digestion of an intact antibody, one of skill will appreciate that such fragments may be synthesized de novo either chemically or by using recombinant DNA methodology. Thus, the term antibody, as used herein, also includes antibody fragments either produced by the modification of whole antibodies, or those synthesized de novo using recombinant DNA methodologies (e.g., single chain Fv) or those identified using phage display libraries (see. e.g., McCafferty et al.. Nature 348:552-554 (1990)). The term “antibody” as referred to herein further includes antibody variants such as single domain antibodies. Thus, in embodiments an antibody includes a single monomeric variable antibody domain. Thus, in embodiments, the antibody, includes a variable light chain (VL) domain or a variable heavychain (VH) domain. In embodiments, the antibody is a variable light chain (VL) domain or a variable heavy chain (VH) domain.

[0152] An “antibody variant” as provided herein refers to a polypeptide capable of binding to an antigen and including one or more structural domains (e.g., light chain variable domain, heavy chain variable domain) of an antibody or fragment thereof. Non-limiting examples of antibody variants include single-domain antibodies or nanobodies, monospecific Fab2, bispecific Fab2, trispecific Fabs, monovalent IgGs, scFv, bispecific antibodies, bispecific diabodies, trispecific triabodies, scFv-Fc, minibodies, IgNAR, V-NAR, hcIgG, VhH, or peptibodies. A “peptibody” or “affibody” as provided herein refers to a peptide moiety attached (through a covalent or non-covalent linker) to the Fc domain or Fc region of an antibody. Further nonlimiting examples of antibody variants known in the art include antibodies produced by cartilaginous fish or camelids. A general description of antibodies from camelids and the variable regions thereof and methods for their production, isolation, and use may be found in references WO97 / 49805 and WO 97 / 49805 which are incorporated by reference herein in their entirety and for all purposes. Likewise, antibodies from cartilaginous fish and the variable regions thereof and methods for their production, isolation, and use may be found in W02005 / 118629, which is incorporated by reference herein in its entirety and for all purposes.

[0153] An “affibody” as described herein is commonly well known in the art and refers to small, robust proteins engineered to bind to a large number of target proteins or peptides with high affinity, by imitating monoclonal antibodies. Affibodies are therefore a member of the family of antibody mimetics. In embodiments, an affibody is a molecule including of three alpha helices with about 58 amino acids and a molar mass of about 6 kDa.

[0154] The term "biparatopic antibody" provided herein is used according to its common meaning in the biological arts and refers to a bispecific antibody including two antigen binding regions, each of which recognizes unique, non-overlapping epitopes on the same target antigen. Without being bound to any particular theory, compared to monoclonal antibodies, biparatopic antibodies may exhibit a superior ability to promote receptor clustering, which may in turn result in improved receptor internalization, lysosomal trafficking, and receptor down regulation and therefore improved drug potency. In embodiments, a biparatopic antibody includes a first antibody region including a heavy chain and a light chain; and a second antibody regionincluding a heavy chain and a light chain. In embodiments, the heavy chain of the first antibody region and the heavy chain of the second antibody region are different. In embodiments, the light chain of the first antibody region and the light chain of the second antibody region are different. In embodiments, a biparatopic antibody includes a first heavy chain, a first light chain, a second heavy chain and a second light chain, wherein the first heavy chain and the second heavy chain are different and wherein the first light chain and the second light chain are different. As provided herein the antibody regions (e.g., a first antibody region, a second antibody region) of a biparatopic antibody are different, when the first antibody region binds a first epitope of a target antigen and the second antibody region binds a second epitope of the same target antigen and the first epitope does not overlap with the second epitope. Thus, the first epitope and the second epitope form different parts of the same antigen. Likewise, the respective light chains and heavy chains (e.g., first light chain and second light chain, first heavy chain and second heavy chain) of a biparatopic antibody are different, when the first light chain and first heavy chain binds a first epitope of a target antigen and the second light chain and second heavy chain binds a second epitope of the same target antigen and the first epitope does not overlap with the second epitope.

[0155] For preparation of monoclonal or polyclonal antibodies, any technique known in the art can be used (see, e.g., Kohler & Milstein, Nature 256:495-497 (1975); Kozbor et al..Immunology Today 4:72 (1983); Cole et al., pp. 77-96 in Monoclonal Antibodies and Cancer Therapy (1985)). " Monoclonal" antibodies (mAb) refer to antibodies derived from a single clone. Techniques for the production of single chain antibodies (U. S. Pat. No. 4,946,778) can be adapted to produce antibodies to polypeptides of this invention. Also, transgenic mice, or other organisms such as other mammals, may be used to express humanized antibodies. Alternatively, phage display technology can be used to identify antibodies and heteromeric Fab fragments that specifically bind to selected antigens (see, e.g., McCafferty et al., Nature 348:552-554 (1990); Marks et al., Biotechnology 10:779-783 (1992)).

[0156] The epitope of a mAb is the region of its antigen to which the mAb binds. Two antibodies bind to the same or overlapping epitope if each competitively inhibits (blocks) binding of the other to the antigen. That is, a lx, 5x, lOx, 20x or lOOx excess of one antibody inhibits binding of the other by at least 30% but preferably 50%, 75%, 90% or even 99% asmeasured in a competitive binding assay (see, e.g., Junghans et al., Cancer Res. 50:1495, 1990). Alternatively, two antibodies have the same epitope if essentially all amino acid mutations in the antigen that reduce or eliminate binding of one antibody reduce or eliminate binding of the other. Two antibodies have overlapping epitopes if some amino acid mutations that reduce or eliminate binding of one antibody reduce or eliminate binding of the other.

[0157] A single-chain variable fragment (scFv) is typically a fusion protein of the variable regions of the heavy (VH) and light chains (VL) of immunoglobulins, connected with a linker. The linker may be a short linker peptide of 10 to about 25 amino acids and be rich in glycine for flexibility, as well as serine or threonine for solubility. The linker can either connect the N-terminus of the VH with the C-terminus of the VL, or vice versa. For the purpose of the compositions provided therein the linker may be an Fc gamma receptor domain (e.g., a CD 16 domain, a CD32 domain, a CD64 domain). Thus, in embodiments, the Fc gamma receptor domain (e.g., a CD16 domain, a CD32 domain, a CD64 domain) connects the N-terminus of the VH with the C-terminus of the VL, or vice versa.

[0158] For preparation of suitable antibodies of the invention and for use according to the invention, e.g., recombinant, monoclonal, or polyclonal antibodies, many techniques known in the art can be used (see, e.g., Kohler & Milstein, Nature 256:495-497 (1975); Kozbor et al., Immunology Today 4: 72 (1983); Cole et al., pp. 77-96 in Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, Inc. (1985); Coligan, Current Protocols in Immunology (1991); Harlow & Lane, Antibodies, A Laboratory Manual (1988); and Goding, Monoclonal Antibodies:Principles and Practice (2d ed. 1986)). The genes encoding the heavy and light chains of an antibody of interest can be cloned from a cell, e.g., the genes encoding a monoclonal antibody can be cloned from a hybridoma and used to produce a recombinant monoclonal antibody. Gene libraries encoding heavy and light chains of monoclonal antibodies can also be made from hybridoma or plasma cells. Random combinations of the heavy and light chain gene products generate a large pool of antibodies with different antigenic specificity (see, e.g., Kuby, Immunology (3rd ed. 1997)). Techniques for the production of single chain antibodies or recombinant antibodies (U. S. Patent 4,946,778, U. S. Patent No. 4,816,567) can be adapted to produce antibodies to polypeptides of this invention. Also, transgenic mice, or other organisms such as other mammals, may be used to express humanized or human antibodies (see, e.g., U. S.Patent Nos. 5,545,807; 5,545,806; 5,569,825; 5,625,126; 5,633,425; 5,661,016, Marks et al., Bio / Technology 10:779-783 (1992); Lonberg et al., Nature 368:856-859 (1994); Morrison, Nature 368:812-13 (1994); Fishwild et al., Nature Biotechnology 14:845-51 (1996); Neuberger, Nature Biotechnology 14:826 (1996); and Lonberg & Huszar. Intern. Rev. Immunol. 13:65-93 (1995)). Alternatively, phage display technology can be used to identify antibodies and heteromeric Fab fragments that specifically bind to selected antigens (see, e.g., McCafferty et al., Nature 348:552-554 (1990); Marks et al., Biotechnology 10:779-783 (1992)). Antibodies can also be made bispecific, i.e., able to recognize two different antigens (see, e.g., WO 93 / 08829, Traunecker et al.. EMBO J. 10:3655-3659 (1991); and Suresh et al., Methods in Enzymology 121:210 (1986)). Antibodies can also be heteroconjugates, e.g., two covalently joined antibodies, or immunotoxins (see, e.g., U. S. Patent No. 4,676,980, WO 91 / 00360; WO 92 / 200373; and EP 03089).

[0159] The term "antigen" as provided herein refers to molecules being bound by the antigen binding domain provided herein. An "antigen binding domain" as provided herein is or includes a region of an antibody or antibody variant as provided herein that binds to an antigen (epitope). As described above, the antigen binding domain may include one constant and one variable domain of each of the heavy and the light chain (VL, VH, CL and CHI, respectively) or binding domains characteristic of antibody variants or fragments. The paratope or antigen-binding site is formed on the N-terminus of the antigen binding domain. The two variable domains of an antigen binding domain typically bind the epitope on an antigen. The antigen binding domain provided herein may include a domain of an antibody (e.g., a light chain variable (VL) domain, a heavy chain variable (VH) domain) or a fragment of an antibody (e.g., Fab). The antigen binding domain may include a light chain variable (VL) domain and / or a heavy chain variable (VH) domain. Thus, in embodiments, the antigen binding domain includes a single domain antibody. In embodiments, the antigen binding domain includes a light chain variable (VL) domain. In embodiments, the antigen binding domain includes a heavy chain variable (VH) domain. In embodiments, the antigen binding domain is a single domain antibody. In embodiments, the single domain antibody includes a heavy chain variable (VH) domain. In embodiments, the single domain antibody includes a light chain variable (VL) domain. Inembodiments, the single domain antibody is a heavy chain variable (VH) domain. In embodiments, the single domain antibody is a light chain variable (VL) domain.

[0160] Non-limiting examples of antigen binding domains include antibodies, antibody fragments, antibody variants as well as recombinant polypeptides having the ability to bind antigens. In embodiments, the antigen binding domain is a Fab. In embodiments, the antigen binding domain is a single domain antibody (sdAb).

[0161] Methods for humanizing or primatizing non-human antibodies are well known in the art (e.g., U. S. Patent Nos. 4,816,567; 5,530,101; 5,859,205; 5,585,089; 5,693,761; 5,693,762;5,777,085; 6,180,370; 6,210,671; and 6,329.511; WO 87 / 02671; EP Patent Application 0173494; Jones et al. (1986) Nature 321:522; and Verhoyen et al. (1988) Science 239:1534). Humanized antibodies are further described in, e.g., Winter and Milstein (1991)Nature 349:293. Generally, a humanized antibody has one or more amino acid residues introduced into it from a source which is non-human. These non-human amino acid residues are often referred to as import residues, which are typically taken from an import variable domain. Humanization can be essentially performed following the method of Winter and co-workers (see, e.g., Morrison et al., PNAS USA, 81:6851-6855 (1984), Jones et al., Nature 321:522-525 (1986); Riechmann et al., Nature 332:323-327 (1988); Morrison and Oi, Adv. Immunol., 44:65-92 (1988), Verhoeyen et al., Science 239:1534-1536 (1988) and Presta, Curr. Op. Struct. Biol. 2:593-596 (1992), Padlan, Molec. Immun., 28:489-498 (1991); Padlan, Molec. Immun., 31(3): 169-217 (1994)), by substituting rodent CDRs or CDR sequences for the corresponding sequences of a human antibody. Accordingly, such humanized antibodies are chimeric antibodies (U. S. Patent No. 4,816,567), wherein substantially less than an intact human variable domain has been substituted by the corresponding sequence from a non-human species. In practice, humanized antibodies are typically human antibodies in which some CDR residues and possibly some FR residues are substituted by residues from analogous sites in rodent antibodies. For example, polynucleotides comprising a first sequence coding for humanized immunoglobulin framework regions and a second sequence set coding for the desired immunoglobulin complementarity determining regions can be produced synthetically or by combining appropriate cDNA and genomic DNA segments. Human constant region DNA sequences can be isolated in accordance with well known procedures from a variety of human cells.

[0162] A "chimeric antibody" is an antibody molecule in which (a) the constant region, or a portion thereof, is altered, replaced or exchanged so that the antigen binding site (variable region) is linked to a constant region of a different or altered class, effector function and / or species, or an entirely different molecule which confers new properties to the chimeric antibody, e.g., an enzyme, toxin, hormone, growth factor, drug, etc.; or (b) the variable region, or a portion thereof, is altered, replaced or exchanged with a variable region having a different or altered antigen specificity. The preferred antibodies of, and for use according to the invention include humanized and / or chimeric monoclonal antibodies.

[0163] Techniques for conjugating therapeutic agents to antibodies are well known (see, e.g., Amon et al., " Monoclonal Antibodies For Immunotargeting Of Drugs In Cancer Therapy", in Monoclonal Antibodies And Cancer Therapy, Reisfeld et al. (eds.), pp. 243-56 (Alan R. Liss, Inc. 1985); Hellstrom et al., “Antibodies For Drug Delivery”in Controlled Drug Delivery (2ndEd.), Robinson et al. (eds.), pp. 623-53 (Marcel Dekker. Inc. 1987); Thorpe, " Antibody Carriers Of Cytotoxic Agents In Cancer Therapy: A Review" in Monoclonal Antibodies ‘84: Biological And Clinical Applications, Pinchera et al. (eds.), pp. 475-506 (1985); and Thorpe et al., " The Preparation And Cytotoxic Properties Of Antibody-Toxin Conjugates", Immunol. Rev., 62:119-58 (1982)). As used herein, the term “antibody-drug conjugate” or “ADC” refers to a therapeutic agent conjugated or otherwise covalently bound to to an antibody.

[0164] A "therapeutic agent" as referred to herein, is a composition useful in treating or preventing a disease such as cancer (e.g., leukemia). In embodiments, the therpaeutic agent is an anti-cancer agent. “Anti-cancer agent” is used in accordance with its plain ordinary meaning and refers to a composition (e.g. compound, drug, antagonist, inhibitor, modulator) having antineoplastic properties or the ability to inhibit the growth or proliferation of cells. In embodiments, an anti-cancer agent is a chemotherapeutic. In embodiments, an anti-cancer agent is an agent identified herein having utility in methods of treating cancer. In embodiments, an anti-cancer agent is an agent approved by the FDA or similar regulatory agency of a country other than the USA, for treating cancer.

[0165] The phrase "specifically (or selectively) binds" to an antibody or "specifically (or selectively) immunoreactive with," when referring to a protein or peptide, refers to a binding reaction that is determinative of the presence of the protein, often in a heterogeneous populationof proteins and other biologies. Thus, under designated immunoassay conditions, the specified antibodies bind to a particular protein at least two times the background and more typically more than 10 to 100 times background. Specific binding to an antibody under such conditions requires an antibody that is selected for its specificity for a particular protein. For example, polyclonal antibodies can be selected to obtain only a subset of antibodies that are specifically immunoreactive with the selected antigen and not with other proteins. This selection may be achieved by subtracting out antibodies that cross-react with other molecules. A variety of immunoassay formats may be used to select antibodies specifically immunoreactive with a particular protein. For example, solid-phase ELISA immunoassays are routinely used to select antibodies specifically immunoreactive with a protein (see, e.g., Harlow & Lane, Using Antibodies, A Laboratory Manual (1998) for a description of immunoassay formats and conditions that can be used to determine specific immunoreactivity).

[0166] A "ligand" refers to an agent, e.g., a polypeptide or other molecule, capable of binding to a receptor or antibody, antibody variant, antibody region or fragment thereof.

[0167] The term " IL 1 RAP" as used herein refers to any recombinant or naturally-occurring forms of interleukin- 1 receptor accessory protein (IL 1 RAP) or variants or homologs thereof that maintain IL1RAP activity' (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to IL 1 RAP). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 10, 20, 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring IL 1 RAP polypeptide. In embodiments, IL 1 RAP is substantially identical to the protein identified by the UniProt reference number Q9NPH3 or a variant or homolog having substantial identity thereto.

[0168] " CD3" as referred to herein includes any of the recombinant or naturally-occurring forms of the Cluster of Differentiation 3 (CD3) proteins or variants or homologs thereof that comprise the CD3 complex that mediates signal transduction and maintains CD3 complex activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to the CD3 complex). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared toa naturally occurring CD3 proteins in the CD3 complex. In embodiments, the CD3 protein is substantially identical to the protein identified by the UniProt reference number P04234 or a variant or homolog having substantial identity thereto. In embodiments, the CD3 protein is substantially identical to the protein identified by the UniProt reference number P09693 or a variant or homolog having substantial identity thereto. In embodiments, the CD3 protein is substantially identical to the protein identified by the UniProt reference number P07766 or a variant or homolog having substantial identity thereto.

[0169] " Her2" as referred to herein includes any of the recombinant or naturally-occurring forms of the human epidermal growth factor receptor 2 protein, also known as receptor tyrosineprotein kinase erbB-2, or variants or homologs thereof that maintain Her2 activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to Her2). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring Her2 protein. In embodiments, the Her2 protein is substantially identical to the protein identified by the UniProt reference number P04626 or a variant or homolog having substantial identity thereto.

[0170] " CD123" as referred to herein includes any of the recombinant or naturally -occurring forms of CD123, also known as interleukin 3 receptor, alpha, or variants or homologs thereof that maintain CD 123 activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to CD 123). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring CD 123 protein. In embodiments, the CD 123 protein is substantially identical to the protein identified by the UniProt reference number P26951 or a variant or homolog having substantial identity thereto.

[0171] " CD20" as referred to herein includes any of the recombinant or naturally -occurring forms of CD20, also known as B-lymphocyte antigen CD20, or variants or homologs thereof that maintain CD20 activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to CD20). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence ora portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring CD20 protein. In embodiments, the CD20 protein is substantially identical to the protein identified by the UniProt reference number P11836 or a variant or homolog having substantial identity thereto.

[0172] " Tumor-associated glycoprotein 72" (TAG72) as referred to herein includes any of the recombinant or naturally-occurring forms of TAG72, or variants or homologs thereof that maintain TAG72 activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity' compared to TAG72). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring TAG72 protein.

[0173] " Carcinoembryonic antigen" (CEA) as referred to herein describes a set of highly related glycoproteins involved in cell adhesion and includes any of the recombinant or naturally-occurring forms of CEA variants or homologs thereof that maintain CEA activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to CEA). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to naturally occurring CEA proteins. In embodiments, the CEA protein is substantially identical to the protein identified by the UniProt reference number QI 3984 or a variant or homolog having substantial identity thereto.

[0174] " CD252" as referred to herein includes any of the recombinant or naturally -occurring forms of CD252, also known as 0X40 ligand (OX40L) and tumor necrosis factor ligand superfamily member 4. or variants or homologs thereof that maintain CD252 activity (e.g. within at least 50%. 80%, 90%, 95%. 96%. 97%. 98%. 99% or 100% activity compared to CD252). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring CD252 protein. In embodiments, the CD252 protein is substantially identical to the protein identified by the UniProt reference number P23510 or a variant or homolog having substantial identity’ thereto.

[0175] " Glucocorticoid-induced tumor necrosis factor receptor" (GITR) as referred to herein includes any of the recombinant or naturally -occurring forms of GITR, also known as tumor necrosis factor receptor superfamily member 18, or variants or homologs thereof that maintain GITR activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity- compared to GITR). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring GITR protein. In embodiments, the GITR protein is substantially identical to the protein identified by the UniProt reference number Q9Y5U5 or a variant or homolog having substantial identity thereto.

[0176] " 41BB" or "4-lBB"as referred to herein includes any of the recombinant or naturally-occurring forms of 4 IBB, also known as tumor necrosis factor ligand superfamily member 9, or variants or homologs thereof that maintain 41BB activity (e g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to 4 IBB). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity- across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring 4 IBB protein. In embodiments, the 4 IBB protein is substantially identical to the protein identified by the UniProt reference number P41273 or a variant or homolog having substantial identity thereto.

[0177] The term "effector cell ligand" as provided herein refers to a cell surface molecule expressed on an effector cell of the immune system (e.g., a cytotoxic T cell, a helper T cell, a B cell, a natural killer cell). Upon binding of the first antibody region to the effector cell ligand expressed on the effector cell, the effector cell is activated and able to exert its function (e.g.. selective killing or eradication of malignant, infected or otherwise unhealthy cells). In embodiments, the effector cell ligand is a CD3 protein. In embodiments, the effector cell ligand is a CD 16 protein. In embodiments, the effector cell ligand is a CD32 protein. In embodiments, the effector cell ligand is a NKp46 protein. The first antibody region as provided herein may be an antibody, an antibody variant, a fragment of an antibody or a fragment of an antibody variant.

[0178] A " CD3 protein" as referred to herein includes any of the recombinant or naturally-occurring forms of the Cluster of Differentiation 3 (CD3) proteins or variants or homologsthereof that comprise the CD3 complex that mediates signal transduction and maintains CD3 complex activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to the CD3 complex). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring CD3 proteins in the CD3 complex.

[0179] A "label" or a "detectable moiety" is a composition detectable by spectroscopic, photochemical, biochemical, immunochemical, chemical, or other physical means. For example, useful labels include 32P, fluorescent dyes, electron-dense reagents, enzymes (e.g.. as commonly used in an ELISA), biotin, digoxigenin, or haptens and proteins or other entities which can be made detectable, e.g., by incorporating a radiolabel into a peptide or antibody specifically reactive with a target peptide. Any appropriate method known in the art for conjugating an antibody to the label may be employed, e.g., using methods described in Hermanson, Bioconjugate Techniques 1996, Academic Press, Inc., San Diego.

[0180] " Contacting" is used in accordance with its plain ordinary meaning and refers to the process of allowing at least two distinct species (e.g. antibodies and antigens) to become sufficiently proximal to react, interact, or physically touch. It should be appreciated; how ever, that the resulting reaction product can be produced directly from a reaction between the added reagents or from an intermediate from one or more of the added reagents which can be produced in the reaction mixture.

[0181] The term "contacting" may include allowing two species to react, interact, or physically touch, wherein the tw o species may be, for example, a pharmaceutical composition as provided herein and a cell. In embodiments contacting includes, for example, allowing a pharmaceutical composition as described herein to interact with a cell.

[0182] An “inhibitor” refers to a compound (e.g. antibodies or recombinant protein compositions described herein) that reduces activity when compared to a control, such as absence of the compound or a compound with known inactivity.

[0183] As defined herein, the term “activation”, “activate”, “activating”, “activator” and the like in reference to a protein-inhibitor interaction means positively affecting (e.g. increasing) theactivity or function of the protein relative to the activity or function of the protein in the absence of the activator. In embodiments activation means positively affecting (e.g. increasing) the concentration or levels of the protein relative to the concentration or level of the protein in the absence of the activator. The terms may reference activation, or activating, sensitizing, or up-regulating signal transduction or enzymatic activity or the amount of a protein decreased in a disease. Thus, activation may include, at least in part, partially or totally increasing stimulation, increasing or enabling activation, or activating, sensitizing, or up-regulating signal transduction or enzymatic activity or the amount of a protein associated with a disease (e.g., a protein which is decreased in a disease relative to a non-diseased control). Activation may include, at least in part, partially or totally increasing stimulation, increasing or enabling activation, or activating, sensitizing, or up-regulating signal transduction or enzymatic activity or the amount of a protein

[0184] The terms “agonist,” “activator,” “upregulator,” etc. refer to a substance capable of detectably increasing the expression or activity of a given gene or protein (e.g., IL1RAP or IL-1 receptor). The agonist can increase expression or activity 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or more in comparison to a control in the absence of the agonist. In embodiments, agonist can increase expression or activity 10% in comparison to a control in the absence of the agonist. In embodiments, agonist can increase expression or activity 20% in comparison to a control in the absence of the agonist. In embodiments, agonist can increase expression or activity 30% in comparison to a control in the absence of the agonist. In embodiments, agonist can increase expression or activity 40% in comparison to a control in the absence of the agonist. In embodiments, agonist can increase expression or activity 50% in comparison to a control in the absence of the agonist. In embodiments, agonist can increase expression or activity’ 60% in comparison to a control in the absence of the agonist. In embodiments, agonist can increase expression or activity 70% in comparison to a control in the absence of the agonist. In embodiments, agonist can increase expression or activity 80% in comparison to a control in the absence of the agonist. In embodiments, agonist can increase expression or activity 90% in comparison to a control in the absence of the agonist. In embodiments, agonist can increase expression or activity 95% in comparison to a control in the absence of the agonist. In embodiments, agonist can increase expression or activity’ 95% or more in comparison to a control in the absence of the agonist. In certain instances, expression oractivity is 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 10-fold or higher than the expression or activity in the absence of the agonist. In embodiments, expression or activity is 1.5-fold higher than the expression or activity in the absence of the agonist. In embodiments, expression or activity is 2-fold higher than the expression or activity in the absence of the agonist. In embodiments, expression or activity’ is 3-fold higher than the expression or activity in the absence of the agonist. In embodiments, expression or activity is 4-fold higher than the expression or activity’ in the absence of the agonist. In embodiments, expression or activity is 5-fold higher than the expression or activity in the absence of the agonist. In embodiments, expression or activity’ is 10-fold higher than the expression or activity in the absence of the agonist. In embodiments, expression or activity’ is 10-fold or higher than the expression or activity in the absence of the agonist.

[0185] As defined herein, the term “inhibition”, “inhibit”, “inhibiting” and the like in reference to a protein-inhibitor interaction means negatively affecting (e.g. decreasing) the activity or function of the protein protein (e.g., IL1RAP or IL-1 receptor) relative to the activity or function of the protein in the absence of the inhibitor. In embodiments inhibition means negatively affecting (e.g. decreasing) the concentration or levels of the protein protein (e.g., IL1RAP or IL-1 receptor) relative to the concentration or level of the protein in the absence of the inhibitor. In embodiments inhibition refers to reduction of a disease or symptoms of disease. In embodiments, inhibition refers to a reduction in the activity’ of a particular protein target. Thus, inhibition includes, at least in part, partially or totally blocking stimulation, decreasing, preventing, or delaying activation, or inactivating, desensitizing, or down-regulating signal transduction or enzymatic activity or the amount of a protein. In embodiments, inhibition refers to a reduction of activity of a target protein protein (e.g., IL1RAP or IL-1 receptor) resulting from a direct interaction (e.g. an inhibitor binds to the target protein). In embodiments, inhibition refers to a reduction of activity’ of a target protein protein (e.g., IL 1 RAP or IL-1 receptor) from an indirect interaction (e.g. an inhibitor binds to a protein that activates the target protein, thereby preventing target protein activation).

[0186] The terms “inhibitor,” “repressor” or “antagonist” or “downregulator” interchangeably refer to a substance capable of detectably decreasing the expression or activity of a given gene or protein protein (e.g., IL 1 RAP or IL-1 receptor). The antagonist can decrease expression oractivity 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or more in comparison to a control in the absence of the antagonist. In embodiments, the antagonist can decrease expression or activity 10% in comparison to a control in the absence of the antagonist. In embodiments, the antagonist can decrease expression or activity 20% in comparison to a control in the absence of the antagonist. In embodiments, the antagonist can decrease expression or activity 30% in comparison to a control in the absence of the antagonist. In embodiments, the antagonist can decrease expression or activity 40% in comparison to a control in the absence of the antagonist. In embodiments, the antagonist can decrease expression or activity 50% in comparison to a control in the absence of the antagonist. In embodiments, the antagonist can decrease expression or activity 60% in comparison to a control in the absence of the antagonist. In embodiments, the antagonist can decrease expression or activity 70% in comparison to a control in the absence of the antagonist. In embodiments, the antagonist can decrease expression or activity 80% in comparison to a control in the absence of the antagonist. In embodiments, the antagonist can decrease expression or activity 90% in comparison to a control in the absence of the antagonist. In embodiments, the antagonist can decrease expression or activity 95% in comparison to a control in the absence of the antagonist. In embodiments, the antagonist can decrease expression or activity’ 95% or more in comparison to a control in the absence of the antagonist. In certain instances, expression or activity is 1.5-fold, 2-fold, 3-fold, 4-fold, 5-fold, 10-fold or lower than the expression or activity in the absence of the antagonist. In embodiments, expression or activity is 1.5-fold lower than the expression or activity in the absence of the antagonist. In embodiments, expression or activity is 2-fold lower than the expression or activity in the absence of the antagonist. In embodiments, expression or activity is 3-fold lower than the expression or activity in the absence of the antagonist. In embodiments, expression or activity is 4-fold lower than the expression or activity in the absence of the antagonist. In embodiments, expression or activity is 5-fold lower than the expression or activity in the absence of the antagonist. In embodiments, expression or activity is 10-fold lower than the expression or activity in the absence of the antagonist. In embodiments, expression or activity’ is 10-fold or lower than the expression or activity in the absence of the antagonist.

[0187] The term "expression" includes any step involved in the production of the polypeptide including, but not limited to, transcription, post-transcriptional modification, translation, post-translational modification, and secretion. Expression can be detected using conventional techniques for detecting protein (e.g., ELISA, Western blotting, flow cytometry, immunofluorescence, immunohistochemistry, etc.).

[0188] A "cell" as used herein, refers to a cell carrying out metabolic or other function sufficient to preserve or replicate its genomic DNA. A cell can be identified by well-known methods in the art including, for example, presence of an intact membrane, staining by a particular dye, ability to produce progeny or, in the case of a gamete, ability to combine with a second gamete to produce a viable offspring. Cells may include prokaryotic and eukaryotic cells. Prokaryotic cells include but are not limited to bacteria. Eukaryotic cells include, but are not limited to, yeast cells and cells derived from plants and animals, for example mammalian, insect (e.g., spodoptera) and human cells.

[0189] A "stem cell" as provided herein refers to a cell characterized by the ability of self-renewal through mitotic cell division and the potential to differentiate into a tissue or an organ. Among mammalian stem cells, embryonic stem cells (ES cells) and somatic stem cells (e.g., HSC) can be distinguished. Embryonic stem cells reside in the blastocyst and give rise to embryonic tissues, whereas somatic stem cells reside in adult tissues for the purpose of tissue regeneration and repair. In embodiments, the stem cell is a leukemia stem cell (LSC). A “leukemia stem cell or “LSC” as provided herein refers to a cell capable of initiating the disease (leukemia) when transplanted into immunodeficient animals and can self-renew by giving rise to leukemia in serial transplantations and also partially differentiate into non-LSC bulk blasts that resemble the original disease but are unable to self-renew. An LSC may carry a gene mutation and be able to self-renew through mitotic cell division and differentiate into the hematopoietic lineage carrying said gene mutant or an LSC may remain as immature progenitor cells, also known as blast cells. In embodiments, the LSC expresses CD34.

[0190] The term "recombinant" when used with reference, e.g., to a cell, nucleic acid, protein, or vector, indicates that the cell, nucleic acid, protein or vector, has been modified by the introduction of a heterologous nucleic acid or protein or the alteration of a native nucleic acid or protein, or that the cell is derived from a cell so modified. Thus, for example, recombinant cells express genes that are not found within the native (non-recombinant) form of the cell or express native genes that are otherwise abnormally expressed, under expressed or not expressed at all.Transgenic cells and plants are those that express a heterologous gene or coding sequence, typically as a result of recombinant methods.

[0191] The term "heterologous" when used with reference to portions of a nucleic acid indicates that the nucleic acid comprises two or more subsequences that are not found in the same relationship to each other in nature. For instance, the nucleic acid is typically recombinantly produced, having two or more sequences from unrelated genes arranged to make a new functional nucleic acid, e.g., a promoter from one source and a coding region from another source. Similarly, a heterologous protein indicates that the protein comprises two or more subsequences that are not found in the same relationship to each other in nature (e.g.. a fusion protein).

[0192] The term "exogenous" refers to a molecule or substance (e.g., a compound, nucleic acid or protein) that originates from outside a given cell or organism. For example, an "exogenous promoter" as referred to herein is a promoter that does not originate from the cell or organism it is expressed by. Conversely, the term "endogenous" or "endogenous promoter" refers to a molecule or substance that is native to, or originates within, a given cell or organism.

[0193] As defined herein, the term "inhibition", "inhibit", "inhibiting" and the like in reference to cell proliferation (e.g., cancer cell proliferation) means negatively affecting (e.g., decreasing proliferation) or killing the cell. In some embodiments, inhibition refers to reduction of a disease or symptoms of disease (e.g., cancer, cancer cell proliferation). Thus, inhibition includes, at least in part, partially or totally blocking stimulation, decreasing, preventing, or delaying activation, or inactivating, desensitizing, or dow n-regulating signal transduction or enzymatic activity or the amount of a protein. Similarly, an "inhibitor" is a compound or protein that inhibits a receptor or another protein, e.g., by binding, partially or totally blocking, decreasing, preventing, delaying, inactivating, desensitizing, or down-regulating activity (e.g., a receptor activity or a protein activity).

[0194] “Biological sample” or “sample” refer to materials obtained from or derived from a subject or patient. A biological sample includes sections of tissues such as biopsy and autopsy¬ samples, and frozen sections taken for histological purposes. Such samples include bodily fluids such as blood and blood fractions or products (e.g., serum, plasma, platelets, red blood cells, andthe like), sputum, tissue, cultured cells (e.g., primary cultures, explants, and transformed cells) stool, urine, synovial fluidjoint tissue, synovial tissue, synoviocytes, fibroblast-like synoviocytes, macrophage-like synoviocytes, immune cells, hematopoietic cells, fibroblasts, macrophages, T cells, etc. A biological sample is typically obtained from a eukaryotic organism, such as a mammal such as a primate e.g., chimpanzee or human; cow; dog; cat; a rodent, e.g., guinea pig, rat, mouse; rabbit; or a bird; reptile; or fish.

[0195] A “control” or “standard control” refers to a sample, measurement, or value that serves as a reference, usually a known reference, for comparison to a test sample, measurement, or value. For example, a test sample can be taken from a patient suspected of having a given disease (e.g. cancer) and compared to a known normal (non-diseased) individual (e.g. a standard control subject). A standard control can also represent an average measurement or value gathered from a population of similar individuals (e.g. standard control subjects) that do not have a given disease (i.e. standard control population), e.g., healthy individuals with a similar medical background, same age, weight, etc. A standard control value can also be obtained from the same individual, e.g. from an earlier-obtained sample from the patient prior to disease onset. For example, a control can be devised to compare therapeutic benefit based on pharmacological data (e.g, half-life) or therapeutic measures (e.g., comparison of side effects). Controls are also valuable for determining the significance of data. For example, if values for a given parameter are widely variant in controls, variation in test samples will not be considered as significant. One of skill will recognize that standard controls can be designed for assessment of any number of parameters (e.g. RNA levels, protein levels, specific cell types, specific bodily fluids, specific tissues, synoviocytes, synovial fluid, synovial tissue, fibroblast-like synoviocytes, macrophagelike synoviocytes, etc).

[0196] One of skill in the art will understand which standard controls are most appropriate in a given situation and be able to analyze data based on comparisons to standard control values. Standard controls are also valuable for determining the significance (e.g. statistical significance) of data. For example, if values for a given parameter are widely variant in standard controls, variation in test samples will not be considered as significant.

[0197] “Patient” or “subject in need thereof’ refers to a living organism suffering from or prone to a disease or condition that can be treated by administration of a composition orpharmaceutical composition as provided herein. Non-limiting examples include humans, other mammals, bovines, rats, mice, dogs, monkeys, goat, sheep, cows, deer, and othernon-mammalian animals. In some embodiments, a patient is human.

[0198] The terms “disease” or “condition” refer to a state of being or health status of a patient or subject capable of being treated with the compounds or methods provided herein. The disease may be a cancer. In some further instances, “cancer” refers to human cancers and carcinomas, sarcomas, adenocarcinomas, lymphomas, leukemias, including solid and lymphoid cancers, kidney, breast, lung, bladder, colon, ovarian, prostate, pancreas, stomach, brain, head and neck, skin, uterine, testicular, glioma, esophagus, and liver cancer, including hepatocarcinoma. lymphoma, including B-acute lymphoblastic lymphoma, non-Hodgkin’s lymphomas (e.g., Burkitt’s, Small Cell, and Large Cell lymphomas), Hodgkin’s lymphoma, leukemia (including acute myeloid leukemia (AML), ALL, and CML), or multiple myeloma.

[0199] As used herein, the term “cancer” refers to all types of cancer, neoplasm or malignant tumors found in mammals (e.g., humans), including leukemia, carcinomas and sarcomas.Exemplary cancers that may be treated with a compound or method provided herein include breast cancer, colon cancer, kidney cancer, leukemia, lung cancer, melanoma, ovarian cancer, prostate cancer, pancreatic cancer, brain cancer, liver cancer, gastric cancer or a sarcoma.

[0200] The term “leukemia” refers broadly to progressive, malignant diseases of the blood-forming organs and is generally characterized by a distorted proliferation and development of leukocytes and their precursors in the blood and bone marrow. Leukemia is generally clinically classified on the basis of (1) the duration and character of the disease-acute or chronic; (2) the type of cell involved; myeloid (myelogenous), lymphoid (lymphogenous), or monocytic; and (3) the increase or non-increase in the number abnormal cells in the blood-leukemic or aleukemic (subleukemic). Exemplary leukemias that may be treated with a compound or method provided herein include, for example, acute myeloid leukemia, acute nonlymphocytic leukemia, chronic lymphocytic leukemia, acute granulocytic leukemia, chronic granulocytic leukemia, acute promyelocytic leukemia, adult T-cell leukemia, aleukemic leukemia, a leukocythemic leukemia, basophylic leukemia, blast cell leukemia, bovine leukemia, chronic myelocytic leukemia, leukemia cutis, embryonal leukemia, eosinophilic leukemia. Gross' leukemia, hairy-cell leukemia, hemoblastic leukemia, hemocytoblastic leukemia, histiocytic leukemia, stem cellleukemia, acute monocytic leukemia, leukopenic leukemia, lymphatic leukemia, lymphoblastic leukemia, lymphocytic leukemia, lymphogenous leukemia, lymphoid leukemia, lymphosarcoma cell leukemia, mast cell leukemia, megakaryocytic leukemia, micromyeloblastic leukemia, monocytic leukemia, myeloblastic leukemia, myelocytic leukemia, myeloid granulocytic leukemia, myelomonocytic leukemia, Naegeli leukemia, plasma cell leukemia, multiple myeloma, plasmacytic leukemia, promyelocytic leukemia, Rieder cell leukemia, Schilling's leukemia, stem cell leukemia, subleukemic leukemia, or undifferentiated cell leukemia.

[0201] The term “sarcoma” generally refers to a tumor which is made up of a substance like the embryonic connective tissue and is generally composed of closely packed cells embedded in a fibrillar or homogeneous substance. Sarcomas that may be treated with a compound or method provided herein include a chondrosarcoma, fibrosarcoma, lymphosarcoma, melanosarcoma, myxosarcoma, osteosarcoma, Abernethy's sarcoma, adipose sarcoma, liposarcoma, alveolar soft part sarcoma, ameloblastic sarcoma, botryoid sarcoma, chloroma sarcoma, chorio carcinoma, embryonal sarcoma, Wilms' tumor sarcoma, endometrial sarcoma, stromal sarcoma, Ewing's sarcoma, fascial sarcoma, fibroblastic sarcoma, giant cell sarcoma, granulocytic sarcoma, Hodgkin's sarcoma, idiopathic multiple pigmented hemorrhagic sarcoma, immunoblastic sarcoma of B cells, lymphoma, immunoblastic sarcoma of T-cells, Jensen's sarcoma, Kaposi's sarcoma, Kupffer cell sarcoma, angiosarcoma, leukosarcoma. malignant mesenchymoma sarcoma, parosteal sarcoma, reticulocytic sarcoma, Rous sarcoma, serocystic sarcoma, synovial sarcoma, or telangiectaltic sarcoma.

[0202] The term “melanoma” is taken to mean a tumor arising from the melanocytic system of the skin and other organs. Melanomas that may be treated with a compound or method provided herein include, for example, acral -lentiginous melanoma, amelanotic melanoma, benign juvenile melanoma, Cloudman's melanoma, S91 melanoma, Harding-Passey melanomajuvenile melanoma, lentigo maligna melanoma, malignant melanoma, nodular melanoma, subungal melanoma, or superficial spreading melanoma.

[0203] The term “carcinoma” refers to a malignant new growth made up of epithelial cells tending to infiltrate the surrounding tissues and give rise to metastases. Exemplary carcinomas that may be treated with a compound or method provided herein include, for example, medullary thyroid carcinoma, familial medullary thyroid carcinoma, acinar carcinoma, acinous carcinoma,adenocystic carcinoma, adenoid cystic carcinoma, carcinoma adenomatosum, carcinoma of adrenal cortex, alveolar carcinoma, alveolar cell carcinoma, basal cell carcinoma, carcinoma basocellulare, basaloid carcinoma, basosquamous cell carcinoma, bronchioalveolar carcinoma, bronchiolar carcinoma, bronchogenic carcinoma, cerebriform carcinoma, cholangiocellular carcinoma, chorionic carcinoma, colloid carcinoma, comedo carcinoma, corpus carcinoma, cribriform carcinoma, carcinoma en cuirasse, carcinoma cutaneum, cylindrical carcinoma, cylindrical cell carcinoma, duct carcinoma, carcinoma durum, embryonal carcinoma, encephaloid carcinoma, epiermoid carcinoma, carcinoma epitheliale adenoides. exophytic carcinoma, carcinoma ex ulcere, carcinoma fibrosum, gelatinifomi carcinoma, gelatinous carcinoma, giant cell carcinoma, carcinoma gigantocellulare, glandular carcinoma, granulosa cell carcinoma, hair-matrix carcinoma, hematoid carcinoma, hepatocellular carcinoma, Hurthle cell carcinoma, hyaline carcinoma, hypemephroid carcinoma, infantile embryonal carcinoma, carcinoma in situ, intraepidermal carcinoma, intraepithelial carcinoma, Krompecher's carcinoma, Kulchitzky-cell carcinoma, large-cell carcinoma, lenticular carcinoma, carcinoma lenticulare, lipomatous carcinoma, lymphoepithelial carcinoma, carcinoma medullare, medullary carcinoma, melanotic carcinoma, carcinoma molle, mucinous carcinoma, carcinoma muciparum, carcinoma mucocellulare, mucoepidermoid carcinoma, carcinoma mucosum, mucous carcinoma, carcinoma myxomatodes, nasopharyngeal carcinoma, oat cell carcinoma, carcinoma ossificans, osteoid carcinoma, papillary carcinoma, periportal carcinoma, preinvasive carcinoma, prickle cell carcinoma, pultaceous carcinoma, renal cell carcinoma of kidney, reserve cell carcinoma, carcinoma sarcomatodes. Schneiderian carcinoma, scirrhous carcinoma, carcinoma scroti, signetring cell carcinoma, carcinoma simplex, small-cell carcinoma, solanoid carcinoma, spheroidal cell carcinoma, spindle cell carcinoma, carcinoma spongiosum, squamous carcinoma, squamous cell carcinoma, string carcinoma, carcinoma telangiectaticum, carcinoma telangiectodes, transitional cell carcinoma, carcinoma tuberosum, tuberous carcinoma, verrucous carcinoma, or carcinoma villosum.

[0204] As used herein, the terms "metastasis," "metastatic," and "metastatic cancer" can be used interchangeably and refer to the spread of a proliferative disease or disorder, e.g., cancer, from one organ or another non-adjacent organ or body part. Cancer occurs at an originating site, e.g., breast, which site is referred to as a primary tumor, e.g., primary breast cancer. Somecancer cells in the primary tumor or originating site acquire the ability to penetrate and infiltrate surrounding normal tissue in the local area and / or the ability to penetrate the walls of the lymphatic system or vascular system circulating through the system to other sites and tissues in the body. A second clinically detectable tumor formed from cancer cells of a primary tumor is referred to as a metastatic or secondary tumor. When cancer cells metastasize, the metastatic tumor and its cells are presumed to be similar to those of the original tumor. Thus, if lung cancer metastasizes to the breast, the secondary tumor at the site of the breast consists of abnormal lung cells and not abnormal breast cells. The secondary tumor in the breast is referred to a metastatic lung cancer. Thus, the phrase metastatic cancer refers to a disease in which a subject has or had a primary tumor and has one or more secondary tumors. The phrases non-metastatic cancer or subjects with cancer that is not metastatic refers to diseases in which subjects have a primary tumor but not one or more secondary tumors. For example, metastatic lung cancer refers to a disease in a subject with or with a history of a primary lung tumor and with one or more secondary' tumors at a second location or multiple locations, e.g., in the breast.

[0205] The term "associated" or "associated with" in the context of a substance or substance activity or function associated with a disease (e.g., cancer (e.g. leukemia, acute myeloid leukemia)) means that the disease (e.g., cancer (e.g. leukemia, acute myeloid leukemia)) is caused by (in whole or in part), or a symptom of the disease is caused by (in whole or in part) the substance or substance activity or function. Alternatively, the substance (e.g., IL1RAP) may be an indicator of the disease (e.g., cancer (e.g. leukemia, acute myeloid leukemia)). Thus, an associated substance may serve as a means of targeting disease tissue (e.g., cancer cells (e.g., leukemia stem cells, acute myeloid leukemia cells)).

[0206] As used herein, “treating” or “treatment of’ a condition, disease or disorder or symptoms associated with a condition (e.g., AML), disease or disorder refers to an approach for obtaining beneficial or desired results, including clinical results. Beneficial or desired clinical results can include, but are not limited to, alleviation or amelioration of one or more symptoms or conditions, diminishment of extent of condition, disorder or disease, stabilization of the state of condition, disorder or disease, prevention of development of condition, disorder or disease, prevention of spread of condition, disorder or disease, delay or slowing of condition, disorder or disease progression, delay or slowing of condition, disorder or disease onset, amelioration orpalliation of the condition, disorder or disease state, and remission, whether partial or total. “Treating” can also mean prolonging survival of a subject beyond that expected in the absence of treatment. “Treating” can also mean inhibiting the progression of the condition, disorder or disease, slowing the progression of the condition, disorder or disease temporarily, although in some instances, it involves halting the progression of the condition, disorder or disease permanently. As used herein the terms treatment, treat, or treating refers to a method of reducing the effects of one or more symptoms of a disease or condition characterized by expression of the protease or symptom of the disease or condition characterized by expression of the protease. Thus in the disclosed method, treatment can refer to a 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% reduction in the severity of an established disease, condition, or symptom of the disease or condition. For example, a method for treating a disease is considered to be a treatment if there is a 10% reduction in one or more symptoms of the disease in a subject as compared to a control. Thus the reduction can be a 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, or any percent reduction in between 10% and 100% as compared to native or control levels. It is understood that treatment does not necessarily refer to a cure or complete ablation of the disease, condition, or symptoms of the disease or condition. Further, as used herein, references to decreasing, reducing, or inhibiting include a change of 10%. 20%. 30%. 40%, 50%, 60%, 70%, 80%, 90% or greater as compared to a control level and such terms can include but do not necessarily include complete elimination.

[0207] The terms “dose” and “dosage” are used interchangeably herein. A dose refers to the amount of active ingredient given to an individual at each administration. The dose will vary depending on a number of factors, including the range of normal doses for a given therapy, frequency of administration; size and tolerance of the individual; severity of the condition; risk of side effects; and the route of administration. One of skill will recognize that the dose can be modified depending on the above factors or based on therapeutic progress. The term “dosage form” refers to the particular format of the pharmaceutical or pharmaceutical composition, and depends on the route of administration. For example, a dosage form can be in a liquid form for nebulization, e.g., for inhalants, in a tablet or liquid, e.g., for oral delivery, or a saline solution, e.g., for injection.

[0208] By “therapeutically effective dose or amount” as used herein is meant a dose that produces effects for which it is administered (e.g. treating or preventing a disease such as AML). The exact dose and formulation will depend on the purpose of the treatment, and will be ascertainable by one skilled in the art using known techniques (see, e.g., Lieberman, Pharmaceutical Dosage Forms (vols. 1-3, 1992); Lloyd, The Art, Science and Technology of Pharmaceutical Compounding (1999); Remington: The Science and Practice of Pharmacy, 20th Edition, Gennaro, Editor (2003), and Pickar, Dosage Calculations (1999)). For example, for the given parameter, a therapeutically effective amount will show an increase or decrease of at least 5%. 10%, 15%, 20%, 25%, 40%, 50%, 60%, 75%, 80%, 90%, or at least 100%. Therapeutic efficacy can also be expressed as “-fold” increase or decrease. For example, a therapeutically effective amount can have at least a 1.2-fold, 1.5-fold, 2-fold, 5-fold, or more effect over a standard control. A therapeutically effective dose or amount may ameliorate one or more symptoms of a disease. A therapeutically effective dose or amount may prevent or delay the onset of a disease or one or more symptoms of a disease when the effect for which it is being administered is to treat a person who is at risk of developing the disease.

[0209] As used herein, the term "administering" means oral administration, administration as a suppository, topical contact, intravenous, intraperitoneal, intramuscular, intralesional, intrathecal, intranasal or subcutaneous administration, or the implantation of a slow-release device, e.g., a mini-osmotic pump, to a subject. Administration is by any route, including parenteral and transmucosal (e.g., buccal, sublingual, palatal, gingival, nasal, vaginal, rectal, or transdermal). Parenteral administration includes, e.g., intravenous, intramuscular, intra-arteriole, intradermal, subcutaneous, intraperitoneal, intraventricular, and intracranial. Other modes of delivery include, but are not limited to, the use of liposomal formulations, intravenous infusion, transdermal patches, etc. By "co-administer" it is meant that a composition described herein is administered at the same time, just prior to, or just after the administration of one or more additional therapies, for example cancer therapies such as chemotherapy, hormonal therapy, radiotherapy, or immunotherapy. The compounds of the invention can be administered alone or can be coadministered to the patient. Coadministration is meant to include simultaneous or sequential administration of the compounds individually or in combination (more than one compound). Thus, the preparations can also be combined, when desired, with other activesubstances (e.g. to reduce metabolic degradation). The compositions of the present invention can be delivered by transdermally, by a topical route, formulated as applicator sticks, solutions, suspensions, emulsions, gels, creams, ointments, pastes, jellies, paints, powders, and aerosols.

[0210] The compositions of the present invention may additionally include components to provide sustained release and / or comfort. Such components include high molecular weight, anionic mucomimetic polymers, gelling polysaccharides and finely -divided drug carrier substrates. These components are discussed in greater detail in U. S. Pat. Nos. 4,911,920;5,403,841; 5,212,162; and 4,861,760. The entire contents of these patents are incorporated herein by reference in their entirety’ for all purposes. The compositions of the present invention can also be delivered as microspheres for slow release in the body. For example, microspheres can be administered via intradermal injection of drug-containing microspheres, which slowly release subcutaneously (see Rao, J. Biomater Sci. Polym. Ed. 7:623-645, 1995; as biodegradable and injectable gel formulations (see, e.g., Gao Pharm. Res. 12:857-863. 1995); or, as microspheres for oral administration (see, e.g., Eyles, J. Pharm. Pharmacol. 49:669-674, 1997). In embodiments, the formulations of the compositions of the present invention can be delivered by the use of liposomes which fuse with the cellular membrane or are endocytosed, i.e.. by employing receptor ligands attached to the liposome, that bind to surface membrane protein receptors of the cell resulting in endocytosis. By using liposomes, particularly where the liposome surface carries receptor ligands specific for target cells, or are otherwise preferentially directed to a specific organ, one can focus the delivery of the compositions of the present invention into the target cells in vivo. (See, e.g., Al-Muhammed, J. Microencapsul. 13:293-306, 1996; Chonn, Curr. Opin. Biotechnol. 6:698-708, 1995; Ostro, Am. J. Hosp. Pharm. 46: 1576-1587, 1989). The compositions of the present invention can also be delivered as nanoparticles.

[0211] As used herein, the term “pharmaceutically acceptable” is used synonymously with “physiologically acceptable” and “pharmacologically acceptable”. A pharmaceutical composition will generally comprise agents for buffering and preservation in storage, and can include buffers and carriers for appropriate delivery, depending on the route of administration.

[0212] " Pharmaceutically acceptable excipient" and "pharmaceutically acceptable carrier" refer to a substance that aids the administration of an active agent to and absorption by a subject and can be included in the compositions of the present invention without causing a significantadverse toxicological effect on the patient. Non-limiting examples of pharmaceutically acceptable excipients include water, NaCl, normal saline solutions, lactated Ringer’s, normal sucrose, normal glucose, binders, fillers, disintegrants, lubricants, coatings, sweeteners, flavors, salt solutions (such as Ringer's solution), alcohols, oils, gelatins, carbohydrates such as lactose, amylose or starch, fatty acid esters, hydroxymethy cellulose, polyvinyl pyrrolidine, and colors, and the like. Such preparations can be sterilized and, if desired, mixed with auxiliary agents such as lubricants, preservatives, stabilizers, wetting agents, emulsifiers, salts for influencing osmotic pressure, buffers, coloring, and / or aromatic substances and the like that do not deleteriously react with the compounds of the invention. One of skill in the art will recognize that other pharmaceutical excipients are useful in the present invention.

[0213] The term "pharmaceutically acceptable salt" refers to salts derived from a variety of organic and inorganic counter ions well known in the art and include, by way of example only, sodium, potassium, calcium, magnesium, ammonium, tetraalkylammonium, and the like; and when the molecule contains a basic functionality, salts of organic or inorganic acids, such as hydrochloride, hydrobromide, tartrate, mesylate, acetate, maleate, oxalate and the like.

[0214] The term "preparation" is intended to include the formulation of the active compound with encapsulating material as a carrier providing a capsule in which the active component with or without other carriers, is surrounded by a carrier, which is thus in association with it.Similarly, cachets and lozenges are included. Tablets, powders, capsules, pills, cachets, and lozenges can be used as solid dosage forms suitable for oral administration.

[0215] The pharmaceutical preparation is optionally in unit dosage form. In such form the preparation is subdivided into unit doses containing appropriate quantities of the active component. The unit dosage form can be a packaged preparation, the package containing discrete quantities of preparation, such as packeted tablets, capsules, and powders in vials or ampoules. Also, the unit dosage form can be a capsule, tablet, cachet, or lozenge itself, or it can be the appropriate number of any of these in packaged form. The unit dosage form can be of a frozen dispersion.

[0216] " Interleukin 15" or " IL-15" or as referred to herein includes any of the recombinant or naturally-occurring forms of IL-15 protein or variants or homologs thereof that maintain IL-15activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to IL-15 protein). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring IL-15 protein. In embodiments, the IL-15 protein is substantially identical to the protein identified by the NCBI Reference Sequence: NP_001230468.1 or a variant or homolog having substantial identity thereto.

[0217] " IL-15RA" as referred to herein includes any of the recombinant or naturally -occurring forms of IL- 15 receptor alpha protein or variants or homologs thereof that maintain IL- 15 receptor alpha activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to IL- 15 receptor alpha protein). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100. 150 or 200 continuous amino acid portion) compared to a naturally occurring IL- 15 receptor alpha protein. In embodiments, the IL-15 receptor alpha protein is substantially identical to the protein identified by the NCBI Reference Sequence: NP_000576.1 or a variant or homolog having substantial identity thereto. In embodiments, the IL- 15 receptor alpha protein is substantially identical to the protein identified by the NCBI Reference Sequence: NP_001243694.1 or a variant or homolog having substantial identity thereto. In embodiments, the IL-15 receptor alpha protein is substantially identical to the protein identified by the NCBI Reference Sequence: NP_002180.1 or a variant or homolog having substantial identity thereto. In embodiments, the IL- 15 receptor alpha protein is substantially identical to the protein identified by the NCBI Reference Sequence: NP_751950.2 or a variant or homolog having substantial identity thereto. In embodiments, the IL- 15 receptor alpha protein is substantially identical to the protein identified by the NCBI Reference Sequence: NP_001338024.1 or a variant or homolog having substantial identity thereto. In embodiments, the second ligand binding domain enhancer is an IL- 15 domain enhancer. In embodiments, the IL-15 domain enhancer is an IL-15RA domain. In embodiments, the IL-15RA domain includes a sushi domain. In embodiments, the IL-15RA domain is a sushi domain.

[0218] An " PD-1 protein" or " PD-1" as referred to herein includes any of the recombinant or naturally-occurring forms of the Programmed cell death protein 1 (PD-1) also known as clusterof differentiation 279 (CD 279) or variants or homologs thereof that maintain PD-1 protein activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to PD-1 protein). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring PD-1 protein. In embodiments, the PD-1 protein is substantially identical to the protein identified by the UniProt reference number Q15116 or a variant or homolog having substantial identity thereto. In embodiments, the PD-1 protein is substantially identical to the protein identified by the UniProt reference number Q02242 or a variant or homolog having substantial identity thereto.

[0219] An " PD-L1 protein" or " PD-L1" as referred to herein includes any of the recombinant or naturally-occurring forms of the Programmed death ligand 1 (PD-L1) also know n as cluster of differentiation 274 (CD 274) or B7 homolog, or variants or homologs thereof that maintain PD-L1 protein activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to PD-L1 protein). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring PD-L1 protein. In embodiments, the PD-L1 protein is substantially identical to the protein identified by the UniProt reference number Q9NZQ7 or a variant or homolog having substantial identity thereto. In embodiments, the PD-L1 protein is substantially identical to the protein identified by the UniProt reference number Q9EP73 or a variant or homolog having substantial identity thereto.COMPOSITIONS

[0220] Provided herein are, inter alia, polypeptides and covalent complexes including the same with multivalent binding specificity. The polypeptides include an Fc receptor portion / domain (e.g., a CD 16 domain, a CD32 domain, a CD64 domain and variants thereof) with a cysteine amino acid substitution capapble of forming a disulfide linkeage with a second cysteine amino acid substitution in an Fc domain (e.g., an Fc domain of IgGl, IgG2, IgG3, IgG4) thereby forming a covalent complex. The covalent disulfide linkage between the Fc receptor portion / domain provided herein including embodiments thereof, and the Fc domain occurs inaddition to the natural binding of an Fc and an Fc receptor molecule. The Fc domain may be attached to an antigen binding domain (e.g., a Fab, an scFv, an antibody variant). Likewise, the Fc receptor domain may be decorated with a functional biologic moiety (e.g., an antigen binding domain, an effector binding domain, a cytokine domain, a cytokine receptor domain or any combination thereof) on its N-terminus or C-terminus or on its N-terminus and C-terminus. Therefore, the covalent complexes provided herein including embodiments thereof, may be multivalent binding complexes with multiple immunotherapeutic functionalities including cancer cell targeting, effector cell (e.g., T cells, NK cells) activation and recruitment as well as inducing ADCC (antibody -dependent cellular cytotoxicity). Upon administration in vivo the polypeptides and covalent complexes provided herein exhibit highly specific binding and reduced or no endogenous Fc receptor binding activity thereby resulting in therapeutics that lack undesirable side effects.FC GAMMA RECEPTOR DOMAINS

[0221] The recombinant polypeptides provided herein including embomdiments thereof, inter alia, include an Fc gamma receptor domain with a cysteine amino acid substitution. The cysteine amino acid substitution provides for the recombinant polypeptide to be covalently linked to an Fc domain through a disulfide linkeage between said cysteine amino acid substitution and a cysteine amino acid substitution included in the Fc domain. The Fc gamma receptor domain provided herewith may include any naturally occurring Fc gamma receptor (e.g., FCRGI, II, or III), Fc gamma receptor variants or functional portions thereof which are modified to include a cysteine amino acid substitution to form the disulfide linkeage. Provided herein are, iner alia, exemplary (wildtype) Fc gamma receptor domains and sequences thereof to be used as template sequence to form Fc gamma receptor domains including a cysteine amino acid substitution for disulfide linkeage formation. Further provided herein are exemplary modified Fc gamma receptor domains which include a cysteine amino acid substitution at a certain position. Any Fc gamma receptor domain known in the art may be modified to include a cysteine substitution to provide for the compositions provided herein. Fc gamma receptor domains include without limitation, Fc gamma receptors I, Fc gamma receptors II, Fc gamma receptors III, (.e.g., CD16, CD32, and CD64), any variants (e.g., CD16A, CD16B), or variantsincluding allelic variants thereof, (e.g., SNPs), homologs, isoforms or functional fragments thereof.

[0222] An Fc gamma receptor is modified to include a cysteine amino acid substitution using standard methods known and used in the molecular biology arts to modify a polypeptide to include an amino acid mutation (substitution) at one or more positions relative to the wildtype sequence. If a protein, peptide or polypeptide (e.g., a CD 16 domain) has been modified to include an amino acid substitution at a certain position (e.g., position 106), the protein, peptide or polypeptide (e.g., a CD 16 domain) includes an amino acid (e.g., cysteine) that is different relative to the original amino acid (e.g., isoleucine) at that position.I. Polypeptides including a CD16 domain

[0223] In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 106 of CD 16.

[0224] In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 134 of CD16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 137 of CD 16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD 16 domain including a cysteine at a position corresponding to amino acid position 176 of CD16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD 16 domain including a cysteine at a position corresponding to amino acid position 131 of CD 16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD 16 domain including a cysteine at a position corresponding to amino acid position 134 of CD16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 178 of CD 16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 179 of CD16.

[0225] In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 150 of CD 16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD 16 domain including a cysteine at a position corresponding to amino acid position 152 of CD16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD 16 domain including a cysteine at a position corresponding to amino acid position 153 of CD16.

[0226] In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 106 of CD 16 and a third cysteine at a position corresponding to amino acid position 134 of CD 16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD 16 domain including a cysteine at a position corresponding to amino acid position 106 of CD16 and a third cysteine at a position corresponding to amino acid position 137 of CD16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD 16 domain including a cysteine at a position corresponding to amino acid position 106 of CD16 and a third cysteine at a position corresponding to amino acid position 179 of CD16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 137 of CD16 and a third cysteine at a position corresponding to amino acid position 179 of CD 16. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 137 of CD16, a third cysteine at a position corresponding to amino acid position 179 of CD16 and a fourth cysteine at a position corresponding to amino acid position 180 of CD 16.

[0227] In aspects wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 106 of CD16 the polypeptides provided herein including embodiments thereof may include at least one additional cysteine. In embodiments, the polypeptide includes one additional cysteine. In embodiments, the oneadditional cysteine is a third cysteine. In embodiments, the third cysteine is at a position corresponding to amino acid position 134 of CD 16. In embodiments, the third cysteine is at a position corresponding to amino acid position 137 of CD 16. In embodiments, the third cysteine is at a position corresponding to amino acid position 179 of CD 16.

[0228] In aspects wherein the Fc gamma receptor domain is a CD16 domain including a cysteine at a position corresponding to amino acid position 137 of CD16 the polypeptides provided herein including embodiments thereof may include at least one additional cysteine (e.g., 1, 2, 3, or 4 additional cysteins in addition to the cysteine at a position corresponding to amino acid position 137). In embodiments, the polypeptide includes one additional cysteine. In embodiments, the one additional cysteine is a third cysteine. In embodiments, the third cysteine is at a position corresponding to amino acid position 179 of CD 16. In embodiments, the polypeptide includes two additional cysteines. In embodiments, the two additional cysteines are a third cysteine and a fourth cysteine. In embodiments, the third cysteine is at a position corresponding to amino acid position 179 of CD 16 and the fourth cysteine is at a position corresponding to amino acid position 180 of CD16

[0229] In embodiments, the CD 16 domain is a CD 16a domain or a CD 16b domain. The terms “CD 16” and “CD 16 domain,” “CD 16a” and “CD 16a domain,” “CD 16b” and “CD 16b domain” as set forth herein may be used interchangeably. In embodiments, the CD16 domain is a CD16a domain. In embodiments, the CD 16 domain is a CD 16b domain. In a further embodiment, the CD 16a domain includes the sequence of SEQ ID NO:4. In a further embodiment, the CD16a domain is the sequence of SEQ ID NO:4. In a further embodiment, the CD16b domain includes the sequence of SEQ ID NO:5. In a further embodiment, the CD16a domain includes the sequence of SEQ ID NO:20. In a further embodiment, the CD16a domain is the sequence of SEQ ID NO:20. In a further embodiment, the CD 16b domain includes the sequence of SEQ ID NO:21. In a further embodiment, the CD16b domain is the sequence of SEQ ID NO:21.

[0230] In embodiments, the CD 16 domain includes an amino acid sequence corresponding to amino acids 8-174 of CD16. In embodiments, the CD16 domain includes an amino acid sequence corresponding to amino acids 19-193 of CD 16.

[0231] " CD16" as referred to herein includes any of the recombinant or naturally -occurring forms of the Cluster of Differentiation 16a (CD16a) and Cluster of Differentiation 16b (CD16b) protein, also known as low affinity immunoglobulin gamma Fc region receptor III-A (FCGR3A) and low affinity immunoglobulin gamma Fc region receptor III-B (FCGR3B), or isoforms, variants or homologs thereof that maintain CD16 activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to CD16). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring CD16 protein. In embodiments, the CD 16 protein is substantially identical to the protein identified by the UniProt reference number P08637 or a variant or homolog having substantial identity thereto. In embodiments, the CD 16 protein is substantially identical to the protein identified by the UniProt reference number 075015 or a variant or homolog having substantial identity thereto. In embodiments, the CD 16 protein is substantially identical to the protein identified by the UniProt reference number A0A8V8TNB3 or a variant or homolog having substantial identity thereto. In embodiments, the CD 16 protein is substantially identical to the protein identified by the UniProt reference number A0A8V8TNB8 or a variant or homolog having substantial identity thereto. In embodiments, the CD 16 protein is substantially identical to the protein identified by the UniProt reference number A0A8V8TPL1 or a variant or homolog having substantial identity thereto. In embodiments, the CD 16 protein is substantially identical to the protein identified by the UniProt reference number H0Y755 or a variant or homolog having substantial identity thereto. In embodiments, the CD 16 protein is substantially identical to the protein identified by the UniProt reference number C9JC71 or a variant or homolog having substantial identity thereto. In embodiments, the CD 16 protein is substantially identical to the protein identified by the UniProt reference number C9JC71 or a variant or homolog having substantial identity thereto. In embodiments, the CD 16 protein is substantially identical to the protein identified by the UniProt reference number 075015 or a variant or homolog having substantial identity thereto.

[0232] In embodiments, the CD16 is a CD16 domain including an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 is a CD16 domain including an amino acidsequence having 85% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues.

[0233] In embodiments, the CD 16 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20. or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:4. In embodiments, the CD16 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD16 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:21.

[0234] In embodiments, the CD 16 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having 85% sequence identity7to the sequence of SEQ ID NO:4. In embodiments, the CD16 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD 16 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD 16 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO:21.

[0235] In embodiments, the CD 16 is a CD 16 domain including an amino acid sequence having at least 90% sequence identity7to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 is a CD16 domain including an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acidresidues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120. 130, 140. 150, 160, or 170 continguous amino acid residues.

[0236] In embodiments, the CD 16 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO:4. In embodiments, the CD 16 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD16 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO:21.

[0237] In embodiments, the CD 16 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO:4. In embodiments, the CD16 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD 16 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO: 20. In embodiments, the CD 16 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO:21.

[0238] In embodiments, the CD 16 is a CD 16 domain including an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD 16 is a CD16 domain including an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. Inanother further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues.

[0239] In embodiments, the CD 16 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:4. In embodiments, the CD16 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD16 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:21.

[0240] In embodiments, the CD 16 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO:4. In embodiments, the CD16 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD 16 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO:21.

[0241] In embodiments, the CD 16 is a CD 16 domain including an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 is a CD16 domain including an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100. 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20. 30. 40. 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues.

[0242] In embodiments, the CD 16 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO:4. In embodiments, the CD 16 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD16 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO:21.

[0243] In embodiments, the CD 16 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO:4. In embodiments, the CD 16 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD 16 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO:21.

[0244] In embodiments, the CD 16 is a CD 16 domain including an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 is a CD16 domain including an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues.

[0245] In embodiments, the CD 16 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having at least97% sequence identity to the sequence of SEQ ID NO:4. In embodiments, the CD16 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD16 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:21.

[0246] In embodiments, the CD 16 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO:4. In embodiments, the CD16 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD 16 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO:21.

[0247] In embodiments, the CD 16 is a CD 16 domain including an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 is a CD16 domain including an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100. 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20. 30. 40. 50. 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues.

[0248] In embodiments, the CD 16 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO:4. In embodiments, the CD 16 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD16 domain includes an amino acid sequence having at least98% sequence identity to the sequence of SEQ ID NO: 20. In embodiments, the CD 16 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO:21.

[0249] In embodiments, the CD 16 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NON. In embodiments, the CD16 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD 16 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO:21

[0250] In embodiments, the CD 16 is a CD 16 domain including an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 is a CD16 domain including an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues.

[0251] In embodiments, the CD 16 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO:4. In embodiments, the CD16 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO:5. In embodiments, the CD16 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO:21.

[0252] In embodiments, the CD 16 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO: 4. In embodiments, the CD 16 domain includes an amino acid sequence having 99% sequence identity’ to the sequence of SEQ ID NO:5. In embodiments, the CD 16 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO:21.

[0253] In embodiments, the CD 16 is a CD 16 domain including an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In a further embodiment, the sequence identity’ is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40. 50. 60. 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 continguous amino acid residues.

[0254] In embodiments, the CD 16 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:20, or SEQ ID NO:21. In embodiments, the CD16 domain includes an amino acid sequence having 100% sequence identity’ to the sequence of SEQ ID NON. In embodiments, the CD16 domain includes an amino acid sequence having 100% sequence identity’ to the sequence of SEQ ID NO:5. In embodiments, the CD 16 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO:20. In embodiments, the CD 16 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO:21.

[0255] In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity’ is across 20-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 30-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 40-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity’ is across 50-200 continguous aminoacid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 60-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 70-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 80-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 90-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 100-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 110-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 120-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 130-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 140-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 150-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 160-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 170-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 180-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 190-200 continguous amino acid residues.

[0256] In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-190 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-180 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-170 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-160 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-150 continguous amino acid residues. In embodiments, the 85%, 90%,95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-140 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-130 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-120 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-110 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-100 continguous amino acid residues In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-90 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-80 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-70 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-60 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-50 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-40 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-30 continguous amino acid residues.

[0257] In embodiments, the CD16 includes the sequence of SEQ ID NO:4. In embodiments, the CD16 includes the sequence of SEQ ID NO:5. In embodiments, the CD16 is the sequence of SEQ ID NO:4. In embodiments, the CD16 is the sequence of SEQ ID NO:5. In embodiments, the CD16 includes the sequence of SEQ ID NO:20. In embodiments, the CD16 includes the sequence of SEQ ID NO:21. In embodiments, the CD16 is the sequence of SEQ ID NO:20. In embodiments, the CD16 is the sequence of SEQ ID NO:21. In embodiments, the CD16 is CD16a. In embodiments, the CD 16 is CD 16b. In embodiments, the CD 16 is CD 16a domain. In embodiments, the CD 16 is CD 16b domain.

[0258] In embodiments, the CD 16 domain is a mammal CD 16 domain. In embodiments, the CD 16 domain is a human CD 16 domain. In embodiments, the CD 16 domain is a mouse CD 16 domain.

[0259] In embodiments, the CD16 domain includes the sequence of SEQ ID NO:4 modified to include a cysteine at a position corresponding to amino acid position 106. In embodiments, the CD 16 domain includes the sequence of SEQ ID NO: 5 modified to include a cysteine at a position corresponding to amino acid position 106. In embodiments, the CD 16 domain is the sequence of SEQ ID NON modified to include a cysteine at a position corresponding to amino acid position 106. In embodiments, the CD16 domain is the sequence of SEQ ID NO:5 modified to include a cysteine at a position corresponding to amino acid position 106. In embodiments, the CD 16 domain includes the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 106. In embodiments, the CD16 domain is the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 106. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 106. In embodiments, the CD16 domain is the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 106. In one further embodiment, the cysteine substitutes an isoleucine at a position corresponding to amino acid position 106.

[0260] In embodiments, the CD16 domain includes the sequence of SEQ ID NO:4 modified to include a cysteine at a position corresponding to amino acid position 134. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:5 modified to include a cysteine at a position corresponding to amino acid position 134. In embodiments, the CD16 domain is the sequence of SEQ ID NO:4 modified to include a cysteine at a position corresponding to amino acid position 134. In embodiments, the CD16 domain is the sequence of SEQ ID NO:5 modified to include a cysteine at a position corresponding to amino acid position 134. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 134. In embodiments, the CD16 domain is the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 134. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 134. In embodiments, the CD16 domain is the sequence of SEQ ID NO: 21 modified to include a cysteine at a position corresponding to amino acid position 134. In one further embodiment, the cysteine substitutes a threonine at a position corresponding to amino acid position 134.

[0261] In embodiments, the CD16 domain includes the sequence of SEQ ID NO:4 modified to include a cysteine at a position corresponding to amino acid position 137. In embodiments, the CD 16 domain includes the sequence of SEQ ID NO: 5 modified to include a cysteine at a position corresponding to amino acid position 137. In embodiments, the CD16 domain is the sequence of SEQ ID NO:4 modified to include a cysteine at a position corresponding to amino acid position 137. In embodiments, the CD16 domain is the sequence of SEQ ID NO:5 modified to include a cysteine at a position corresponding to amino acid position 137. In embodiments, the CD 16 domain includes the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 137. In embodiments, the CD16 domain is the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 137. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 137. In embodiments, the CD16 domain is the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 137. In one further embodiment, the cysteine substitutes a histidine at a position corresponding to amino acid position 137.

[0262] In embodiments, the CD16 domain includes the sequence of SEQ ID NO:4 modified to include a cysteine at a position corresponding to amino acid position 176. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:5 modified to include a cysteine at a position corresponding to amino acid position 176. In embodiments, the CD16 domain is the sequence of SEQ ID NO:4 modified to include a cysteine at a position corresponding to amino acid position 176. In embodiments, the CD16 domain is the sequence of SEQ ID NO:5 modified to include a cysteine at a position corresponding to amino acid position 176. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 176. In embodiments, the CD16 domain is the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 176. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 176. In embodiments, the CD16 domain is the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 176. In one further embodiment, the cysteine substitutes a phenylalanine at a position corresponding to amino acid position 176.

[0263] In embodiments, the CD16 domain includes the sequence of SEQ ID NO:4 modified to include a cysteine at a position corresponding to amino acid position 131. In embodiments, the CD 16 domain includes the sequence of SEQ ID NO: 5 modified to include a cysteine at a position corresponding to amino acid position 131. In embodiments, the CD 16 domain is the sequence of SEQ ID NON modified to include a cysteine at a position corresponding to amino acid position 131. In embodiments, the CD16 domain is the sequence of SEQ ID NO:5 modified to include a cysteine at a position corresponding to amino acid position 131. In embodiments, the CD 16 domain includes the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 131. In embodiments, the CD16 domain is the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 131. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 131. In embodiments, the CD16 domain is the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 131. In one further embodiment, the cysteine substitutes a tryptophane at a position corresponding to amino acid position 131.

[0264] In embodiments, the CD16 domain includes the sequence of SEQ ID NON modified to include a cysteine at a position corresponding to amino acid position 178. In embodiments, the CD 16 domain includes the sequence of SEQ ID NON modified to include a cysteine at a position corresponding to amino acid position 178. In embodiments, the CD16 domain is the sequence of SEQ ID NON modified to include a cysteine at a position corresponding to amino acid position 178. In embodiments, the CD16 domain is the sequence of SEQ ID NON modified to include a cysteine at a position corresponding to amino acid position 178. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 178. In embodiments, the CD16 domain is the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 178. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 178. In embodiments, the CD1 domain is the sequence of SEQ ID NO: 21 modified to include a cysteine at a position corresponding to amino acid position 178. In one further embodiment, the cysteine substitutes a serine at a position corresponding to amino acid position 178.

[0265] In embodiments, the CD16 domain includes the sequence of SEQ ID NO:4 modified to include a cysteine at a position corresponding to amino acid position 179. In embodiments, the CD 16 domain includes the sequence of SEQ ID NO: 5 modified to include a cysteine at a position corresponding to amino acid position 179. In embodiments, the CD16 domain is the sequence of SEQ ID NON modified to include a cysteine at a position corresponding to amino acid position 179. In embodiments, the CD16 domain is the sequence of SEQ ID NO:5 modified to include a cysteine at a position corresponding to amino acid position 179. In embodiments, the CD 16 domain includes the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 179. In embodiments, the CD16 domain is the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 179. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 179. In embodiments, the CD16 domain is the sequence of SEQ ID NO:21 modified to include a cysteine at a position corresponding to amino acid position 179. In one further embodiment, the cysteine substitutes a lysine at a position corresponding to amino acid position 179.

[0266] In embodiments, the CD16 domain includes the sequence of SEQ ID NO: 1 or SEQ ID NO:2. In embodiments, the CD16 domain includes the sequence of SEQ ID NO: 1. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:2. In embodiments, the CD 16 domain is the sequence of SEQ ID NO: 1 or SEQ ID NO:2. In embodiments, the CD16 domain is the sequence of SEQ ID NO: 1. In embodiments, the CD16 domain is the sequence of SEQ ID NO:2. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:238. In embodiments, the CD 16 domain is the sequence of SEQ ID NO:238.

[0267] In embodiments, the CD16 domain includes the sequence of SEQ ID NO:20 or SEQ ID NO:21. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:20. In embodiments, the CD16 domain includes the sequence of SEQ ID NO:21. In embodiments, the CD16 domain is the sequence of SEQ ID NO:20 or SEQ ID NO:21. In embodiments, the CD16 domain is the sequence of SEQ ID NO:20. In embodiments, the CD16 domain is the sequence of SEQ ID NO:21.

[0268] The amino acid sequence of any of the CD 16 domains provided herein may be mapped to a potein data bank (pdb) CD16 structure conventionally known in the art (e.g., 1183) and aperson having ordinary skill in the art will recognize immediately that, for example, a “position corresponding to amino acid 106” in the CD16 amino acid sequence may be position 88 in the corresponding pdb structure. Likewise, a position corresponding to amino acid 131, may be position 113 in the corresponding pdb structure, a position corresponding to amino acid 134, may be position 116 in the corresponding pdb structure, a position corresponding to amino acid 178, may be position 160 in the corresponding pdb structure, or a position corresponding to amino acid 179, may be position 161 in the corresponding pdb structure.II. Polypeptides including a CD32 domain

[0269] In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD32 domain including a cysteine at a position corresponding to amino acid position 121 of CD32.

[0270] In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD32 domain including a cysteine at a position corresponding to amino acid position 146 of CD32. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD32 domain including a cysteine at a position corresponding to amino acid position 194 of CD32. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD32 domain including a cysteine at a position corresponding to amino acid position 162 of CD32. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD32 domain including a cysteine at aposition corresponding to amino acid position 167 of CD32.

[0271] In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD32 domain including a cysteine at a position corresponding to amino acid position 85 of CD32. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD32 domain including a cysteine at a position corresponding to amino acid position 110 of CD32. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD32 domain including a cysteine at a position corresponding to amino acid position 158 of CD32. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD32 domain including a cysteineat a position corresponding to amino acid position 126 of CD32. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD32 domain including a cysteine at a position corresponding to amino acid position 131 of CD32.

[0272] In embodiments, the CD32 domain includes an amino acid sequence corresponding to amino acids 32-207 of CD32. In embodiments, the CD32 domain is an amino acid sequence corresponding to amino acids 32-207 of CD32.

[0273] " CD32" as referred to herein includes any of the recombinant or naturally -occurring forms of the Cluster of Differentiation 32 (CD32a) and Cluster of Differentiation 32b (CD32b) protein, also known as low affinity immunoglobulin gamma Fc region receptor II-A and low affinity immunoglobulin gamma Fc region receptor II-B, or isoforms, variants or homologs thereof that maintain CD32 activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity' compared to CD32). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity’ across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring CD32 protein. In embodiments, the CD32 protein is substantially identical to the protein identified by the UniProt reference number Pl 2318 or a variant or homolog having substantial identity thereto. In embodiments, the CD32 protein is substantially identical to the protein identified by the UniProt reference number P31994-5 or a variant or homolog having substantial identity thereto. In embodiments, the CD32 protein is substantially identical to the protein identified by the UniProt reference number P31994-4 or a variant or homolog having substantial identity thereto. In embodiments, the CD32 protein is substantially identical to the protein identified by the UniProt reference number P31994-3 or a variant or homolog having substantial identity thereto. In embodiments, the CD32 protein is substantially identical to the protein identified by the UniProt reference number P31994-2 or a variant or homolog having substantial identity thereto. In embodiments, the CD32 protein is substantially identical to the protein identified by the UniProt reference number P31994-1 or a variant or homolog having substantial identity thereto. In embodiments, the CD32 includes the sequence of SEQ ID NO:6. In embodiments, the CD32 includes the sequence of SEQ ID NO:7. In embodiments, the CD32 includes the sequence of SEQ ID NO:8. In embodiments, the CD32includes the sequence of SEQ ID NO:9. In embodiments, the CD32 includes the sequence of SEQ ID NO: 10. In embodiments, the CD32 includes the sequence of SEQ ID NO:11. In embodiments, the CD32 includes the sequence of SEQ ID NO:22. In embodiments, the CD32 is the sequence of SEQ ID NO:6. In embodiments, the CD32 is the sequence of SEQ ID NO: 7. In embodiments, the CD32 is the sequence of SEQ ID NO: 8. In embodiments, the CD32 is the sequence of SEQ ID NO:9. In embodiments, the CD32 is the sequence of SEQ ID NO: 10. In embodiments, the CD32 is the sequence of SEQ ID NO: 11. In embodiments, the CD32 is the sequence of SEQ ID NO:22.

[0274] In embodiments, the CD32 is a CD32 domain including an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 is a CD32 domain including an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO:6, SEQ ID NO:7. SEQ ID NO:8. SEQ ID NO:9. SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210,220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40. 50, 60, 70, 80, 90, 100, 110, 120, 130. 140, 150, 160, 170, 180, 190. 200, 210. 220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210,220, 230, or 240 continguous amino acid residues.

[0275] In embodiments, the CD32 domain includes an amino acid sequence having at least 85% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10. SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:6. In embodiments, the CD32 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:7. In embodiments, the CD32 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:8. In embodiments, the CD32 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:9. In embodiments, the CD32 domain includes an amino acid sequence having at least 85% sequence identity7to the sequence of SEQID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:22.

[0276] In embodiments, the CD32 domain includes an amino acid sequence having 85% sequence identity to the sequence SEQ ID NON, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NON, SEQ ID NO:10, SEQ ID NO:11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO: 6. In embodiments, the CD32 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO: 7. In embodiments, the CD32 domain includes an amino acid sequence having 85% sequence identity7to the sequence of SEQ ID NO: 8. In embodiments, the CD32 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NON. In embodiments, the CD32 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO:22.

[0277] In embodiments, the CD32 is a CD32 domain including an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NON, SEQ ID NON, SEQ ID NO: 8, SEQ ID NON, SEQ ID NO: 10, SEQ ID NO:11, or SEQ ID NO: 22. In embodiments, the CD32 is a CD32 domain including an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NON, SEQ ID NON. SEQ ID NO:8. SEQ ID NON, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210,220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210. 220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210,220, 230, or 240 continguous amino acid residues.

[0278] In embodiments, the CD32 domain includes an amino acid sequence having at least 90% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO:6. In embodiments, the CD32 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO: 7. In embodiments, the CD32 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO:8. In embodiments, the CD32 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO:9. In embodiments, the CD32 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO:22.

[0279] In embodiments, the CD32 domain includes an amino acid sequence having 90% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO: 6. In embodiments, the CD32 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO: 7. In embodiments, the CD32 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO: 8. In embodiments, the CD32 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO: 9. In embodiments, the CD32 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO:22.

[0280] In embodiments, the CD32 is a CD32 domain including an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32is a CD32 domain including an amino acid sequence having 95% sequence identity to the sequence of SEQ ID N0:6, SEQ ID NO:7, SEQ ID N0:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120. 130, 140, 150, 160, 170. 180, 190. 200, 210,220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20. 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150. 160, 170. 180. 190, 200. 210.220. 230, or 240 continguous ammo acid residues.

[0281] In embodiments, the CD32 domain includes an amino acid sequence having at least 95% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:6. In embodiments, the CD32 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:7. In embodiments, the CD32 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:8. In embodiments, the CD32 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:9. In embodiments, the CD32 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:22.

[0282] In embodiments, the CD32 domain includes an amino acid sequence having 95% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO:11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO: 6. In embodiments, the CD32 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO: 7. In embodiments, the CD32 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO: 8. Inembodiments, the CD32 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO: 9. In embodiments, the CD32 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO:22.

[0283] In embodiments, the CD32 is a CD32 domain including an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11. or SEQ ID NO:22. In embodiments, the CD32 is a CD32 domain including an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO:11, or SEQ ID NO:22. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120. 130, 140, 150, 160, 170, 180, 190. 200, 210,220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150. 160, 170. 180, 190, 200, 210,220. 230, or 240 continguous amino acid residues.

[0284] In embodiments, the CD32 domain includes an amino acid sequence having at least 96% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO:6. In embodiments, the CD32 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO:7. In embodiments, the CD32 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO:8. In embodiments, the CD32 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO: 9. In embodiments, the CD32 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having at least 96% sequence identity7to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domainincludes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO:22.

[0285] In embodiments, the CD32 domain includes an amino acid sequence having 96% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11. or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO: 6. In embodiments, the CD32 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO: 7. In embodiments, the CD32 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO: 8. In embodiments, the CD32 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO: 9. In embodiments, the CD32 domain includes an amino acid sequence having 96% sequence identity7to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO: 22.

[0286] In embodiments, the CD32 is a CD32 domain including an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 is a CD32 domain including an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO:11, or SEQ ID NO:22. In a further embodiment, the sequence identity7is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190. 200, 210,220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity7is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170. 180, 190, 200, 210,220. 230, or 240 continguous amino acid residues.

[0287] In embodiments, the CD32 domain includes an amino acid sequence having at least 97% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 domainincludes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:6. In embodiments, the CD32 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:7. In embodiments, the CD32 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:8. In embodiments, the CD32 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:9. In embodiments, the CD32 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:22.

[0288] In embodiments, the CD32 domain includes an amino acid sequence having 97% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO: 6. In embodiments, the CD32 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO: 7. In embodiments, the CD32 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO: 8. In embodiments, the CD32 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO: 9. In embodiments, the CD32 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO:22.

[0289] In embodiments, the CD32 is a CD32 domain including an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 is a CD32 domain including an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO:11, or SEQ ID NO:22. In a further embodiment, the sequence identity is across at least20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210,220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190. 200, 210. 220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210,220, 230, or 240 continguous amino acid residues.

[0290] In embodiments, the CD32 domain includes an amino acid sequence having at least 98% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO:6. In embodiments, the CD32 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO: 7. In embodiments, the CD32 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO: 8. In embodiments, the CD32 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO:9. In embodiments, the CD32 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO:22.

[0291] In embodiments, the CD32 domain includes an amino acid sequence having 98% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11. or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO: 6. In embodiments, the CD32 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO: 7. In embodiments, the CD32 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO: 8. In embodiments, the CD32 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO: 9. In embodiments, the CD32 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, theCD32 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO:22.

[0292] In embodiments, the CD32 is a CD32 domain including an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO:11, or SEQ ID NO: 22. In embodiments, the CD32 is a CD32 domain including an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO 6, SEQ ID NO:7. SEQ ID NO:8. SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210,220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210. 220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210,220, 230, or 240 continguous amino acid residues.

[0293] In embodiments, the CD32 domain includes an amino acid sequence having at least 99% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO:6. In embodiments, the CD32 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO: 7. In embodiments, the CD32 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO: 8. In embodiments, the CD32 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO:9. In embodiments, the CD32 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO:22.

[0294] In embodiments, the CD32 domain includes an amino acid sequence having 99% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO: 6. In embodiments, the CD32 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO: 7. In embodiments, the CD32 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO: 8. In embodiments, the CD32 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO:9. In embodiments, the CD32 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO:22.

[0295] In embodiments, the CD32 is a CD32 domain including an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO: 22. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140. 150, 160, 170. 180, 190. 200, 210,220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, or 240 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130. 140, 150. 160, 170, 180, 190, 200. 210,220, 230, or 240 continguous amino acid residues.

[0296] In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 30-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 40-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 50-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequenceidendity is across 60-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 70-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 80-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 90-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 100-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 110-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 120-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 130-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 140-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 150-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 160-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 170-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 180-200 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 190-200 continguous amino acid residues.

[0297] In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-190 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-180 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-170 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%. or 100% sequence idendity is across 20-160 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-150 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-140 continguous aminoacid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-130 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-120 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-110 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-100 continguous amino acid residues In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-90 continguous amino acid residues. In embodiments, the 85%. 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-80 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-70 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-60 continguous amino acid residues. In embodiments, the 85%. 90%. 95%. 96%. 97%. 98%. 99%. or 100% sequence idendity is across 20-50 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-40 continguous amino acid residues. In embodiments, the 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence idendity is across 20-30 continguous amino acid residues.

[0298] In embodiments, the CD32 domain includes an amino acid sequence having 100% sequence identity to the sequence SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, or SEQ ID NO:22. In embodiments, the CD32 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO: 6. In embodiments, the CD32 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO: 7. In embodiments, the CD32 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO:8. In embodiments, the CD32 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO:9. In embodiments, the CD32 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO: 10. In embodiments, the CD32 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO: 11. In embodiments, the CD32 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO:22.

[0299] In embodiments, the CD32 domain includes the sequence of SEQ ID NO:6, SEQ ID NO:7 SEQ ID NO: 8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO:20 or SEQ ID NO: 11 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain includes the sequence of SEQ ID NO: 6 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain includes the sequence of SEQ ID NO:7 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain includes the sequence of SEQ ID NO: 8 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain includes the sequence of SEQ ID NO:9 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain includes the sequence of SEQ ID NO: 10 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain includes the sequence of SEQ ID NO: 11 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain includes the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 121.

[0300] In embodiments, the CD32 domain is the sequence of SEQ ID NO:6, SEQ ID NO:7 SEQ ID NO: 8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO:20 or SEQ ID NO: 11 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain is the sequence of SEQ ID NO: 6 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain is the sequence of SEQ ID NO:7 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain is the sequence of SEQ ID NO:8 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain is the sequence of SEQ ID NO:9 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain is the sequence of SEQ ID NO: 10 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain is the sequence of SEQ ID NO: 11 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32domain is the sequence of SEQ ID NO:20 modified to include a cysteine at a position corresponding to amino acid position 121.

[0301] In embodiments, the CD32 domain includes the sequence of SEQ ID NO:6 modified to include a cysteine at a position corresponding to amino acid position 121. In embodiments, the CD32 domain is the sequence of SEQ ID NO: 6 modified to include a cysteine at a position corresponding to amino acid position 121. In one further embodiment, the cysteine substitutes a serine at a position corresponding to amino acid position 121.

[0302] In embodiments, the CD32 domain includes the sequence of SEQ ID NO:6 modified to include a cysteine at a position corresponding to amino acid position 146. In embodiments, the CD32 domain is the sequence of SEQ ID NO:6 modified to include a cysteine at a position corresponding to amino acid position 146. In one further embodiment, the cysteine substitutes a tryptophane at a position corresponding to amino acid position 146.

[0303] In embodiments, the CD32 domain includes the sequence of SEQ ID NO:6 modified to include a cysteine at a position corresponding to amino acid position 194. In embodiments, the CD32 domain is the sequence of SEQ ID NO:6 modified to include a cysteine at a position corresponding to amino acid position 194. In one further embodiment, the cysteine substitutes a threonine at a position corresponding to amino acid position 194.

[0304] In embodiments, the CD32 domain includes the sequence of SEQ ID NO:6 modified to include a cysteine at a position corresponding to amino acid position 162. In embodiments, the CD32 domain is the sequence of SEQ ID NO:6 modified to include a cysteine at a position corresponding to amino acid position 162. In one further embodiment, the cysteine substitutes a serine at a position corresponding to amino acid position 162.

[0305] In embodiments, the CD32 domain includes the sequence of SEQ ID NO:6 modified to include a cysteine at a position corresponding to amino acid position 167. In embodiments, the CD32 domain is the sequence of SEQ ID NO:6 modified to include a cysteine at a position corresponding to amino acid position 167. In one further embodiment, the cysteine substitutes a histidine at a position corresponding to amino acid position 167.

[0306] In embodiments, the CD32 includes the sequence of SEQ ID NO:6. In embodiments, the CD32 is the sequence of SEQ ID NO:6.

[0307] The amino acid sequence of the CD32 domain provided herein may be mapped to a potein data bank (pdb) CD32 structure conventionally known in the art (e.g., 3wjj) and a person having ordinary skill in the art will recognize immediately that, for example, a “position corresponding to amino acid 121” in the CD32 amino acid sequence may be position 85 in the corresponding pdb structure. Likewise, a position corresponding to amino acid 194, may be position 158 in the corresponding pdb structure, a position corresponding to amino acid 162, may be position 126 in the corresponding pdb structure, or a position corresponding to amino acid 167, may be position 131 in the corresponding pdb structure.III. Polypeptides including a CD64 domain

[0308] In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 102 of CD64.

[0309] In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 130 of CD64. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 173 of CD64. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 174 of CD64. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 143 of CD64. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 146 of CD64. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 148 of CD64. In an aspect is provided a polypeptideincluding a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 134 of CD64.

[0310] In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 102 of CD64. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 131 of CD64. In an aspect is provided a polypeptide including a Fc gamma receptor domain, wherein the Fc gamma receptor domain is a CD64 domain including a cysteine at a position corresponding to amino acid position 115 of CD64.

[0311] In embodiments, the CD64 domain includes an amino acid sequence corresponding to amino acids 16-187 of CD64. In embodiments, the CD64 domain is an amino acid sequence corresponding to amino acids 16-187 of CD64.

[0312] " CD64" as referred to herein includes any of the recombinant or naturally -occurring forms of the Cluster of Differentiation 64a (CD64a) protein, also known as low affinity immunoglobulin gamma Fc region receptor III-A (FCGR3A) and low affinity immunoglobulin gamma Fc region receptor I, CD64, FCG1, FCRI, FCGR1; IGFR1, FcgammaRI or isoforms, variants or homologs thereof that maintain CD64 activity (e.g. within at least 50%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or 100% activity compared to CD64). In some aspects, the variants or homologs have at least 90%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity across the whole sequence or a portion of the sequence (e.g. a 50, 100, 150 or 200 continuous amino acid portion) compared to a naturally occurring CD64 protein. In embodiments, the CD64 protein is substantially identical to the protein identified by the NCBI reference number NP_000557.1 or a variant or homolog having substantial identity thereto. In embodiments, the CD64 protein is substantially identical to the protein identified by the UniProt reference number P12314 or a variant or homolog having substantial identity thereto.

[0313] In embodiments, the CD64 includes the sequence of SEQ ID NO:83. In embodiments, the CD64 is the sequence of SEQ ID NO: 83. In embodiments, the CD64 includes the sequence of SEQ ID NO:84. In embodiments, the CD64 is the sequence of SEQ ID NO:84. Inembodiments, the CD64 includes the sequence of SEQ ID NO:239. In embodiments, the CD64 is the sequence of SEQ ID NO:239. In embodiments, the CD64 includes the sequence of SEQ ID NO:3. In embodiments, the CD64 is the sequence of SEQ ID NO:3.

[0314] In embodiments, the CD64 is a CD64 domain including an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 is a CD64 domain including an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140. 150, 160. 170, 180, 190, 200, 210. 220, 230, 240, 250, 260. 270, 280. 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350. 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues.

[0315] In embodiments, the CD64 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:83 or SEQ ID NO:84. In embodiments, the CD64 domain includes an ammo acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO:83. In embodiments, the CD64 domain includes an amino acid sequence having at least 85% sequence identity to the sequence of SEQ ID NO: 84.

[0316] In embodiments, the CD64 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 domain includes an ammo acid sequence having 85% sequence identity to the sequence of SEQ ID NO: 83. In embodiments, the CD64 domain includes an amino acid sequence having 85% sequence identity to the sequence of SEQ ID NO: 84.

[0317] In embodiments, the CD64 is a CD64 domain including an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 is a CD64 domain including an amino acid sequence having 90%sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160. 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330. 340, 350. 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20. 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150. 160, 170. 180. 190, 200. 210, 220. 230, 240, 250, 260, 270. 280, 290. 300, 310, 320.330, 340, 350, 360, 370, or 380 continguous amino acid residues.

[0318] In embodiments, the CD64 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO:83 or SEQ ID NO:84. In embodiments, the CD64 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO:83. In embodiments, the CD64 domain includes an amino acid sequence having at least 90% sequence identity to the sequence of SEQ ID NO: 84.

[0319] In embodiments, the CD64 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO: 83. In embodiments, the CD64 domain includes an amino acid sequence having 90% sequence identity to the sequence of SEQ ID NO: 84.

[0320] In embodiments, the CD64 is a CD64 domain including an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 is a CD64 domain including an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350. 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40. 50. 60. 70. 80, 90, 100, 110. 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues. In another furtherembodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues.

[0321] In embodiments, the CD64 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:83 or SEQ ID NO:84. In embodiments, the CD64 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO:83. In embodiments, the CD64 domain includes an amino acid sequence having at least 95% sequence identity to the sequence of SEQ ID NO: 84.

[0322] In embodiments, the CD64 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO: 83. In embodiments, the CD64 domain includes an amino acid sequence having 95% sequence identity to the sequence of SEQ ID NO: 84.

[0323] In embodiments, the CD64 is a CD64 domain including an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 is a CD64 domain including an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140. 150, 160. 170, 180, 190, 200, 210. 220, 230, 240, 250, 260, 270, 280. 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350. 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues.

[0324] In embodiments, the CD64 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO:83 or SEQ ID NO:84. In embodiments, the CD64 domain includes an ammo acid sequence having at least 96% sequence identity to thesequence of SEQ ID NO:83. In embodiments, the CD64 domain includes an amino acid sequence having at least 96% sequence identity to the sequence of SEQ ID NO: 84.

[0325] In embodiments, the CD64 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO: 83. In embodiments, the CD64 domain includes an amino acid sequence having 96% sequence identity to the sequence of SEQ ID NO: 84.

[0326] In embodiments, the CD64 is a CD64 domain including an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 is a CD64 domain including an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160. 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330. 340, 350. 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20. 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues.

[0327] In embodiments, the CD64 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:83 or SEQ ID NO:84. In embodiments, the CD64 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO:83. In embodiments, the CD64 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO: 84.

[0328] In embodiments, the CD64 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 domain includes an amino acid sequence having 97% sequence identity to the sequence ofSEQ ID NO: 83. In embodiments, the CD64 domain includes an amino acid sequence having 97% sequence identity to the sequence of SEQ ID NO: 84.

[0329] In embodiments, the CD64 is a CD64 domain including an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 is a CD64 domain including an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160. 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330. 340, 350. 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20. 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues.

[0330] In embodiments, the CD64 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO:83 or SEQ ID NO:84. In embodiments, the CD64 domain includes an amino acid sequence having at least 98% sequence identity to the sequence of SEQ ID NO:83. In embodiments, the CD64 domain includes an amino acid sequence having at least 97% sequence identity to the sequence of SEQ ID NO: 84.

[0331] In embodiments, the CD64 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO: 83. In embodiments, the CD64 domain includes an amino acid sequence having 98% sequence identity to the sequence of SEQ ID NO: 84.

[0332] In embodiments, the CD64 is a CD64 domain including an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 is a CD64 domain including an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In a furtherembodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40. 50. 60. 70. 80, 90, 100, 110. 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170. 180, 190, 200, 210, 220. 230, 240, 250, 260, 270, 280, 290. 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues.

[0333] In embodiments, the CD64 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO:83 or SEQ ID NO:84. In embodiments, the CD64 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO:83. In embodiments, the CD64 domain includes an amino acid sequence having at least 99% sequence identity to the sequence of SEQ ID NO: 84.

[0334] In embodiments, the CD64 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO: 83. In embodiments, the CD64 domain includes an amino acid sequence having 99% sequence identity to the sequence of SEQ ID NO: 84.

[0335] In embodiments, the CD64 is a CD64 domain including an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO:83 or SEQ ID NO:84. In a further embodiment, the sequence identity is across at least 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160. 170, 180, 190, 200, 210. 220, 230, 240, 250, 260, 270, 280. 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350. 360, 370, or 380 continguous amino acid residues. In another further embodiment, the sequence idendity is across 20. 30. 40. 50, 60, 70, 80, 90, 100, 110, 120, 130.140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, or 380 continguous amino acid residues.

[0336] In embodiments, the CD64 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO: 83 or SEQ ID NO: 84. In embodiments, the CD64 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO:83. In embodiments, the CD64 domain includes an amino acid sequence having 100% sequence identity to the sequence of SEQ ID NO:84.

[0337] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 102. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 102. In one further embodiment, the cysteine substitutes an arginine at a position corresponding to amino acid position 102.

[0338] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 102. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 102. In one further embodiment, the cysteine substitutes an arginine at a position corresponding to amino acid position 102.

[0339] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 130. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 130. In one further embodiment, the cysteine substitutes a lysine at a position corresponding to amino acid position 130.

[0340] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 130. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 130. In one further embodiment, the cysteine substitutes a lysine at a position corresponding to amino acid position 130.

[0341] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 173. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 83 modified to include a cysteine at a positioncorresponding to amino acid position 173. In one further embodiment, the cysteine substitutes a lysine at a position corresponding to amino acid position 173.

[0342] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 173. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 173. In one further embodiment, the cysteine substitutes a lysine at a position corresponding to amino acid position 173.

[0343] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 174. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 174. In one further embodiment, the cysteine substitutes a histidine at a position corresponding to amino acid position 174.

[0344] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 174. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 174. In one further embodiment, the cysteine substitutes a histidine at a position corresponding to amino acid position 174.

[0345] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 143. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 143. In one further embodiment, the cysteine substitutes a alanine at aposition corresponding to amino acid position 143.

[0346] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 143. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 143. In one further embodiment, the cysteine substitutes a alanine at aposition corresponding to amino acid position 143.

[0347] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 146. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 146. In one further embodiment, the cysteine substitutes a phenylalanine at a position corresponding to amino acid position 146.

[0348] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 146. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 146. In one further embodiment, the cysteine substitutes a phenylalanine at a position corresponding to amino acid position 146.

[0349] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 148. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 148. In one further embodiment, the cysteine substitutes a histidine at a position corresponding to amino acid position 148.

[0350] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 148. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 148. In one further embodiment, the cysteine substitutes a histidine at a position corresponding to amino acid position 148.

[0351] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 134. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 83 modified to include a cysteine at a position corresponding to amino acid position 134. In one further embodiment, the cysteine substitutes an asparagine at a position corresponding to amino acid position 134.

[0352] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 84 modified to include a cysteine at a position corresponding to amino acid position 134. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 84 modified to include a cysteine at a positioncorresponding to amino acid position 134. In one further embodiment, the cysteine substitutes an asparagine at a position corresponding to amino acid position 134.

[0353] In embodiments, the CD64 domain includes the sequence of SEQ ID NO: 85. In embodiments, the CD64 domain is the sequence of SEQ ID NO: 85.

[0354] The amino acid sequence of the CD64 domain provided herein may be mapped to a potein data bank (pdb) CD64 structure conventionally known in the art (e.g., 4NZE) and a person having ordinary skill in the art will recognize immediately that, for example, a “position corresponding to amino acid 102” in the CD64 amino acid sequence may be position 102 in the corresponding pdb structure

[0355] The Fc gamma receptor domains (e.g., CD 16 domain, CD32 domain, CD64 domain) provided herein including embodiments thereof may be bound through chemical linkers to antigen binding domains either at the N- or C-terminus of the Fc gamma receptor domain.

[0356] A “chemical linker,” as provided herein, is a covalent linker, a non-covalent linker, a peptide or peptidyl linker (a linker including a peptide moiety), a cleavable peptide linker, a substituted or unsubstituted alkylene, substituted or unsubstituted heteroalkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted heterocycloalkylene, substituted or unsubstituted arylene or substituted or unsubstituted heteroarylene or any combination thereof. Thus, a chemical linker as provided herein may include a plurality of chemical moieties, wherein each of the plurality of chemical moieties is chemically different. Alternatively, the chemical linker may be a non-covalent linker. Examples of non-covalent linkers include without limitation, ionic bonds, hydrogen bonds, halogen bonds, van der Waals interactions (e g. dipoledipole, dipole-induced dipole, London dispersion), ring stacking (pi effects), and hydrophobic interactions. In embodiments, a chemical linker is formed using conjugate chemistry including, but not limited to nucleophilic substitutions (e.g., reactions of amines and alcohols with acyl halides, active esters), electrophilic substitutions (e.g., enamine reactions) and additions to carbon-carbon and carbon-heteroatom multiple bonds (e.g., Michael reaction, Diels-Alder addition).

[0357] The chemical linker as provided herein (e.g., first or second chemical linker), may be -O-,-S-, -C(O)-, -C(O)O-, -C(O)NH-. -S(O)2NH-, -NH-, -NHC(O)NH-, substituted (e.g.,substituted with a substituent group, a size-limited substituent or a lower substituent group) or unsubstituted alkylene, substituted (e.g., substituted with a substituent group, a size-limited substituent or a lower substituent group) or unsubstituted heteroalkylene, substituted (e.g., substituted with a substituent group, a size-limited substituent or a lower substituent group) or unsubstituted cycloalkylene, substituted (e.g., substituted with a substituent group, a size-limited substituent or a lower substituent group) or unsubstituted heterocycloalkylene, substituted (e.g., substituted with a substituent group, a size-limited substituent or a lower substituent group) or unsubstituted arylene or substituted (e.g., substituted with a substituent group, a size-limited substituent or a lower substituent group) or unsubstituted heteroarylene.

[0358] The chemical linker as provided herein (e.g., first or second chemical linker), may be -0-,-S-, -C(O)-, -C(O)O-, -C(O)NH-, -S(O)2NH-, -NH-, -NHC(O)NH-, substituted or unsubstituted (e.g., C1-C20, C1-C10, C1-C5) alkylene, substituted or unsubstituted (e.g., 2 to 20 membered, 2 to 10 membered, 2 to 5 membered) heteroalkylene, substituted or unsubstituted (e.g., C3-C8, C3-C6, C3-C5) cycloalkylene, substituted or unsubstituted (e.g., 3 to 8 membered, 3 to 6 membered, 3 to 5 membered) heterocycloalkylene, substituted or unsubstituted (e.g., Ce-Cio, C6-C8, C6-C5) arylene or substituted or unsubstituted (e.g., 5 to 10 membered, 5 to 8 membered, 5 to 6 membered,) heteroarylene.

[0359] In embodiments, the first chemical linker and the second chemical linker are independently a covalent linker or a non-covalent linker. In embodiments, the first chemical linker and the second chemical linker are independently a peptidyl linker. In embodiments, the first chemical linker and the second chemical linker are independently a cleavable linker. In embodiments, the cleavable linker is a protease cleavable linker. Thus, in embodiments, the first chemical linker and the second chemical linker are independently an enzymatically cleavable linker. In embodiments, the first chemical linker and the second chemical linker are independently a protease cleavable linker. In embodiments, the cleavable linker is a tumor-associated protease cleavable linker.

[0360] In embodiments, the first chemical linker and the second chemical linker are independently a cleavable linker including a protease cleavage site. In some embodiments, the first chemical linker is a cleavable linker that includes a protease cleavage site. In some embodiments, the second chemical linker is a cleavable linker that includes a protease cleavagesite. A "cleavable linker" refers to a linker including an element (e.g., peptide sequence) that is labile to cleavage upon suitable manipulation (e.g., protease activity ). Accordingly, a cleavable linker may comprise any of a number of chemical entities, including amino acids, nucleic acids, or small molecules, among others. A cleavable linker may be cleaved by, for instance, chemical, enzymatic, or physical means. Non-limiting examples of labile elements included in cleavable linkers include protease cleavage sites, nucleic acid sequences cleaved by nucleases, photolabile, acid-labile, or base-labile functional groups. In embodiments, the chemical linker is a protease cleavable linker. In embodiments, the chemical linker is a tumor-associated protease cleavable linker.

[0361] In embodiments, the chemical linker includes a bovine serum albumin (BSA) binding moiety. In embodiments, the chemical linker is pH sensitive linker. The chemical linkers provided herein may include a BSA binding moiety (i.e., a peptide sequence capable of binding to BSA). At a physiological pH said BSA binding moiety is capable of binding to BSA. In embodiments, the BSA binding moiety does not bind to BSA at an acidic pH (e.g., a pH below 7, 6, 5, 4, 3, 2 or 1). While BSA binds to the BSA binding moiety at a physiological pH (i.e. neutral pH, pH 7), BSA increases the half-life and / or stability of the complex provided herein including embodiments thereof relative to the absence of BSA. Upon transition of the complex bound to BSA through the BSA binding moiety from a non-tumor environment to a tumor environment the pH may change from physiological to acidic thereby causing the BSA to dissociate from the BSA binding moiety and releasing the complex to bind to a cancer cell.

[0362] The chemical linkers provided herein, including embodiments thereof, may have different lengths (e.g., include varying numbers of amino acid residues). Thus, in embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of about 0 to about 15 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of about 0 to about 10 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of about 0 to about 9 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of about 0 toabout 8 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of about 0 to about 7 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of about 0 to about 6 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of about 0 to about 5 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of about 0 to about 4 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of about 0 to about 3 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of about 0 to about 2 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of about 0 to about 1 amino acid residues.

[0363] In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 0 to 15 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 0 to 10 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 0 to 9 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 0 to 8 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 0 to 7 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 0 to 6 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 0 to 5 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the thirdchemical linker, and the fourth chemical linker independently have a length of 0 to 4 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 0 to 3 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 0 to 2 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 0 to 1 amino acid residues.

[0364] In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 15 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 10 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 9 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 8 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 7 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 6 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 5 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 4 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 3 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 2 amino acid residues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 1 amino acidresidues. In embodiments, the first chemical linker, the second chemical linker, the third chemical linker, and the fourth chemical linker independently have a length of 0 amino acid residues.

[0365] A "cleavage site" as used herein, refers to a recognizable site for cleavage of a portion of a linker described herein. Thus, a cleavage site may be found in the sequence of a cleavable peptide linker as described herein, including embodiments thereof. In embodiments, the cleavage site is an amino acid sequence that is recognized and cleaved by a cleaving agent (e.g., a peptidyl sequence). In some embodiments, the cleavage site comprises the amino acid sequence VPLSLY (SEQ ID NO: 143). In some embodiments, the cleavage site comprises the amino acid sequence SPLAQAVRSS (SEQ ID NO: 144). Exemplary cleaving agents include proteins, enzymes, DNAzymes, RNAzymes, metals, acids, and bases. In embodiments, the protease cleavage site is a matrix metalloprotease (MMP) cleavage site, a disintegrin and metalloprotease domain-containing (ADAM) metalloprotease cleavage site, a prostate specific antigen (PSA) protease cleavage site, a urokinase-type plasminogen activator (uPA) protease cleavage site, a membrane type serine protease 1 (MT-SP1) protease cleavage site or a legumain protease cleavage site. In embodiments, the matrix metalloprotease (MMP) cleavage site is a MMP 9 cleavage site, a MMP 13 cleavage site or a MMP 2 cleavage site. In embodiments, the disintegrin and metalloprotease domain-containing (ADAM) metalloprotease cleavage site is an ADAM 9 metalloprotease cleavage site, an ADAM 10 metalloprotease cleavage site or an ADAM 17 metalloprot ease cleavage site.

[0366] Further exemplary cleavage sites include the cleavage site of ABHD12, ADAM12, ABHD12B, ABHD13, ABHD17A, ADAM19, ADAM20. ADAM21, ADAM28, ADAM30, ADAM33, ADAM8. ABHD17A, ADAMDEC1, ADAMTS1. ADAMTS10, ADAMTS12, ADAMTS13, ADAMTS14, ADAMTS15, ADAMTS16, ADAMTS17, ADAMTS18, ADAMTS19, ADAMTS2, ADAMTS20, ADAMTS3, ADAMTS4, ABHD17B, ADAMTS5, ADAMTS6, ADAMTS7, ADAMTS8, ADAMTS9, ADAMTSL1, ADAMTSL2, ADAMTSL3, ABHD17C, ADAMTSL5, ASTL, BMP1, CELA1, CELA2A, CELA2B, CELA3A. CELA3B, ADAM10, ADAM15, ADAM17, ADAM9, ADAMTS4, CTSE, CTSF, ADAMTSL4, CMA1, CTRB1, CTRC, CTSO, CTRl, CTSA, CTSW, CTSB, CTSC, CTSD, ESP1, CTSG, CTSH, GZMA, GZMB, GZMH, CTSK, GZMM, CTSL, CTSS, CTSV, CTSZ, HTRA4, KLK10,KLK11, KLK13, KLK14, KLK2, KLK4, DPP4, KLK6, KLK7, KLKB1, ECE1, ECE2, ECEL1, MASP2, MEP1A, MEP1B, ELANE, FAP, GZMA, MMP11, GZMK, HGFAC, HPN, HTRA1, MMP11, MMP16, MMP17, MMP19, HTRA2, MMP20, MMP21, HTRA3, HTRA4, KEL, MMP23B, MMP24, MMP25, MMP26, MMP27, MMP28, KLK5, MMP3, MMP7. MMP8, MMP9, LGMN, LNPEP, MASP1, PAPPA, PAPPA2, PCSK1, NAPSA, PCSK5, PCSK6, MME, MMP1, MMP10, PLAT, PLAU, PLG, PRSS1, PRSS12, PRSS2, PRSS21, PRSS3, PRSS33, PRSS4, PRSS55, PRSS57, MMP12, PRSS8, PRSS9, PRTN3, MMP13, MMP14, ST14,TMPRSS1O, TMPRSS11A, TMPRSS11D, TMPRSS11E, TMPRSS11F, TMPRSS12, TMPRSS13, MMP15, TMPRSS15, MMP2. TMPRSS2. TMPRSS3, TMPRSS4, TMPRSS5. TMPRSS6, TMPRSS7, TMPRSS9, NRDC, OVCH1, PAMR1, PCSK3, PHEX, TINAG, TPSAB1, TPSD1, or TPSG1.

[0367] In embodiments, the cleavable linker is a tumor-associated cleavable linker. In embodiments, the chemical linker is a protease cleavable linker. In embodiments, the chemical linker is a tumor-associated protease cleavable linker. A "tumor-associated protease cleavable linker" as provided herein is an amino acid sequence recognized by a protease, whose expression is specific for a tumor cell or tumor cell environment thereof.

[0368] " Proteases" (or "proteinases", "peptidases", or "proteolytic" enzy mes) generally refer to a class of enzymes that cleave peptide bonds between amino acids of proteins. Because proteases use a molecule of water to effect hydrolysis of peptide bonds, these enzymes can also be classified as hydrolases. Six classes of proteases are presently known: serine proteases, threonine proteases, cysteine proteases, aspartic acid proteases, metalloproteases, and glutamic acid proteases (see, e.g., Barrett A. J. et al. The Handbook of Proteolytic Enzymes, 2nd ed.Academic Press, 2003). A “tumor-associated protease” refers to a class of enzy mes whose expression is specific for a tumor cell or tumor cell environment thereof. A tumor-associated protease may be expressed by a tumor and / or non-tumor cells. Non-limiting examples of proteases contemplated for the invention provided herein including embodiments thereof include ABHD12, ADAM12, ABHD12B, ABHD13, ABHD17A, ADAM19, ADAM20, ADAM21, ADAM28, ADAM30, ADAM33, ADAM8, ABHD17A, ADAMDEC1, ADAMTS1, ADAMTS10, ADAMTS12, ADAMTS13, ADAMTS14, ADAMTS15, ADAMTS16, ADAMTS17, ADAMTS18, ADAMTS19, ADAMTS2, ADAMTS20, ADAMTS3, ADAMTS4,ABHD17B, ADAMTS5, ADAMTS6, ADAMTS7, ADAMTS8, ADAMTS9, ADAMTSL1, ADAMTSL2, ADAMTSL3, ABHD17C, ADAMTSL5, ASTL, BMP1, CELA1, CELA2A, CELA2B, CELA3A, CELA3B, ADAM10, ADAM15, ADAM17, ADAM9, ADAMTS4, CTSE, CTSF, ADAMTSL4. CMA1, CTRB1. CTRC. CTSO, CTRl, CTSA, CTSW, CTSB, CTSC, CTSD, ESP1, CTSG, CTSH, GZMA, GZMB, GZMH, CTSK, GZMM, CTSL, CTSS, CTSV, CTSZ, HTRA4, KLK10, KLK11, KLK13, KLK14, KLK2, KLK4, DPP4, KLK6, KLK7, KLKB1, ECE1, ECE2, ECEL1, MASP2, MEP1A, MEP1B, ELANE, FAP, GZMA, MMP11, GZMK, HGFAC, HPN, HTRA1, MMP11, MMP16, MMP17. MMP19. HTRA2, MMP20, MMP21, HTRA3, HTRA4, KEL, MMP23B, MMP24, MMP25, MMP26, MMP27. MMP28, KLK5, MMP3, MMP7, MMP8, MMP9, LGMN, LNPEP, MASP1, PAPPA, PAPPA2, PCSK1, NAPSA, PCSK5, PCSK6, MME, MMP1, MMP10, PLAT, PLAU, PLG, PRSS1, PRSS12, PRSS2. PRSS21, PRSS3, PRSS33, PRSS4, PRSS55, PRSS57, MMP12, PRSS8, PRSS9.PRTN3, MMP13, MMP14, STM, TMPRSS1O, TMPRSS11A, TMPRSS11D, TMPRSS11E. TMPRSS11F, TMPRSS12, TMPRSS13, MMP15, TMPRSS15, MMP2, TMPRSS2, TMPRSS3, TMPRSS4, TMPRSS5, TMPRSS6, TMPRSS7, TMPRSS9, NRDC, OVCH1, PAMR1, PCSK3, PHEX, TINAG, TPSAB1, TPSD1, and TPSG1

[0369] In embodiments, the chemical linker is a covalent linker. In embodiments, the chemical linker is a bond. In embodiments, the chemical linker is a hydrocarbon linker. In embodiments, the chemical linker is a cleavable peptide linker.

[0370] Thus, a chemical linker as provided herein may include a plurality of chemical moieties, wherein each of the plurality' of chemical moieties is chemically different.Alternatively, the chemical linker may be a non-covalent linker. Examples of non-covalent linkers include without limitation, ionic bonds, hydrogen bonds, halogen bonds, van der Waals interactions (e g. dipole-dipole, dipole-induced dipole, London dispersion), ring stacking (pi effects), and hydrophobic interactions. In embodiments, a chemical linker is formed using conjugate chemistry including, but not limited to nucleophilic substitutions (e.g., reactions of amines and alcohols with acyl halides, active esters), electrophilic substitutions (e.g., enamine reactions) and additions to carbon-carbon and carbon-heteroatom multiple bonds (e.g., Michael reaction, Diels-Alder addition).

[0371] In embodiments, the polypeptide further includes a first antigen binding domain bound to the Fc gamma receptor domain through a first chemical linker. In embodiments, the first antigen binding domain is bound to the N-terminus of the Fc gamma receptor domain. In embodiments, the first antigen binding domain is bound to the C-terminus of the Fc gamma receptor domain.

[0372] In embodiments, the polypeptide further includes a second antigen binding domain bound to the Fc gamma receptor domain through a second chemical linker. In embodiments, the second antigen binding domain is bound to the N-terminus of the Fc gamma receptor domain. In embodiments, the second antigen binding domain is bound to the C-terminus of the Fc gamma receptor domain.

[0373] In embodiments, the first antigen binding domain and the second antigen binding domain are independently an antibody, an antibody domain or an antibody variant. In embodiments, the first antigen binding domain and the second antigen binding domain are the same. In embodiments, the first antigen binding domain and the second antigen binding domain are different. Where the first antigen binding domain and the second antigen binding domain are different, the first antigen binding domain includes a first VL, first VH, first CDR LI, first CDR L2, first CDR L3, first CDR Hl, first CDR H2 and first CDR H3 and the second antigen binding domain includes a second VL, second VH, second CDR LI. second CDR L2. second CDR L3. second CDR Hl, second CDR H2 and second CDR H3, respectively. For the compositions provided herein the first antigen binding domain and the second antigen binding domain may be different, when they bind to different antigens (e.g., a tumor antigen (e.g., ILlRap) and a T cell antigen (e.g., CD3)).

[0374] In embodiments, the first antigen binding domain or the second antigen binding domain is an antibody, an antibody domain or an antibody variant. In embodiments, the first antigen binding domain or the second antigen binding domain is an antibody. In one further embodiment, the first antigen binding domain and the second antigen binding domain bind different antigens. In embodiments, the first antigen binding domain or the second antigen binding domain is an antibody domain. In embodiments, the first antigen binding domain or the second antigen binding domain is a Fab. In embodiments, the first antigen binding domain or the second antigen binding domain is an scFv. In embodiments, the first antigen binding domainor the second antigen binding domain is an antibody variant. In embodiments, the first antigen binding domain or the second antigen binding domain is nanobody.

[0375] In embodiments, the first antigen binding domain is an antibody, an antibody domain or an antibody variant. In embodiments, the first antigen binding domain is an antibody. In embodiments, the first antigen binding domain is an antibody domain. In embodiments, the first antigen binding domain is an antibody variant. In embodiments, the first antigen binding domain is a Fab. In embodiments, the first antigen binding domain is an scFv. In embodiments, the first antigen binding domain is a nanobody.

[0376] In embodiments, the second antigen binding domain is an antibody, an antibody domain or an antibody variant. In embodiments, the second antigen binding domain is an antibody. In embodiments, the second antigen binding domain is an antibody domain. In embodiments, the second antigen binding domain is an antibody variant. In embodiments, the second antigen binding domain is a Fab. In embodiments, the second antigen binding domain is an scFv. In embodiments, the second antigen binding domain is a nanobody.

[0377] In embodiments, the first antigen binding domain and the second antigen binding domain are an antibody, an antibody domain or an antibody variant. In embodiments, the first antigen binding domain and the second antigen binding domain are an antibody. In embodiments, the first antigen binding domain and the second antigen binding domain are an antibody domain. In embodiments, the first antigen binding domain and the second antigen binding domain are an antibody variant. In embodiments, the first antigen binding domain and the second antigen binding domain is an scFv. In embodiments, the first antigen binding domain and the second antigen binding domain is an antibody variant. In embodiments, the first antigen binding domain and the second antigen binding domain is nanobody.

[0378] In embodiments, the first antigen binding domain and the second antigen binding domain are independently a variable light (VL) domain or a variable heavy (VH) domain. In embodiments, the first antigen binding domain or the second antigen binding domain is a variable light (VL) domain or a variable heavy (VH) domain. In embodiments, the first antigen binding domain or the second antigen binding domain is a variable light (VL) domain. Inembodiments, the first antigen binding domain or the second antigen binding domain is a variable heavy (VH) domain.

[0379] In embodiments, the first antigen binding domain is a variable light (VL) domain or a variable heavy (VH) domain. In embodiments, the first antigen binding domain is a variable light (VL) domain. In embodiments, the first antigen binding domain is a variable heavy (VH) domain.

[0380] In embodiments, the second antigen binding domain is a variable light (VL) domain or a variable heavy (VH) domain. In embodiments, the second antigen binding domain is a variable light (VL) domain. In embodiments, the second antigen binding domain is a variable heavy (VH) domain.

[0381] In embodiments, the first antigen binding domain is a variable light domain and the second antigen binding domain is a variable heavy domain. In embodiments, the first antigen binding domain is a variable heavy domain and the second antigen binding domain is a variable light domain.

[0382] In embodiments, first antigen binding domain is attached to the N-terminus of the Fc gamma receptor domain and the second antigen binding domain is attached to the C-terminus of the Fc gamma receptor domain.

[0383] In embodiments, the first antigen binding domain and the second antigen binding domain are independently an scFv. In embodiments, the first antigen binding domain or the second antigen binding domain is an scFv. In embodiments, the first antigen binding domain is an scFv. In embodiments, the second antigen binding domain is an scFv. In embodiments, the first antigen binding domain and the second antigen binding domain are an scFv.

[0384] In embodiments, the first antigen binding domain and the second antigen binding domain are independently a CD3 binding domain. In embodiments, the first antigen binding domain or the second antigen binding domain is a CD3 binding domain. In embodiments, the first antigen binding domain is a CD3 binding domain. In embodiments, the second antigen binding domain is a CD3 binding domain. In embodiments, the first antigen binding domain and the second antigen binding domain are a CD3 binding domain.

[0385] In embodiments, the first antigen binding domain and the second antigen binding domain independently include the sequence of SEQ ID NO:34, SEQ ID NO:39, or SEQ ID NO:58. In embodiments, the first antigen binding domain or the second antigen binding domain include the sequence of SEQ ID NO:34, SEQ ID NO:39, or SEQ ID NO:58. In embodiments, the first antigen binding domain includes the sequence of SEQ ID NO:34, SEQ ID NO:39, or SEQ ID NO:58. In embodiments, the first antigen binding domain includes the sequence of SEQ ID NO: 34. In embodiments, the first antigen binding domain includes the sequence of SEQ ID NO: 39. In embodiments, the first antigen binding domain includes the sequence of SEQ ID NO:58. In embodiments, the second antigen binding domain includes the sequence of SEQ ID NO:34, SEQ ID NO:39, or SEQ ID NO:58. In embodiments, the second antigen binding domain includes the sequence of SEQ ID NO:34. In embodiments, the second antigen binding domain includes the sequence of SEQ ID NO:39. In embodiments, the second antigen binding domain includes the sequence of SEQ ID NO:58.

[0386] In embodiments, the first antigen binding domain and the second antigen binding domain independently are the sequence of SEQ ID NO:34, SEQ ID NO:39, or SEQ ID NO:58. In embodiments, the first antigen binding domain or the second antigen binding domain is the sequence of SEQ ID NO:34, SEQ ID NO:39, or SEQ ID NO:58. In embodiments, the first antigen binding domain is the sequence of SEQ ID NO:34, SEQ ID NO:39. or SEQ ID NO:58. In embodiments, the first antigen binding domain is the sequence of SEQ ID NO:34. In embodiments, the first antigen binding domain is the sequence of SEQ ID NO: 39. In embodiments, the first antigen binding domain is the sequence of SEQ ID NO: 58. In embodiments, the second antigen binding domain is the sequence of SEQ ID NO: 34, SEQ ID NO:39, or SEQ ID NO:58. In embodiments, the second antigen binding domain is the sequence of SEQ ID NO:34. In embodiments, the second antigen binding domain is the sequence of SEQ ID NO:39. In embodiments, the second antigen binding domain is the sequence of SEQ ID NO:58.

[0387] In embodiments, the first antigen binding domain and the second antigen binding domain are independently a cancer antigen binding domain. In embodiments, the first antigen binding domain or the second antigen binding domain is a cancer antigen binding domain. In embodiments, the first antigen binding domain is a cancer antigen binding domain. Inembodiments, the second antigen binding domain is a cancer antigen binding domain. In embodiments, the first antigen binding domain and the second antigen binding domain are a cancer antigen binding domain.

[0388] The first antigen binding domain and second antigen binding domain provided herein may independently be an antibody, an antibody fragment (e.g., a Fab), or an antibody variant (e.g., scFv, a nanobody or a single domain antibody). Thus, in embodiments, the first antigen binding domain and the second antigen binding domain independently include (i) a CDR LI, a CDR L2, a CDR L3, a CDR Hl, a CDR H2, and a CDR H3; (ii) a CDR LI, a CDR L2. and a CDR L3; or (iii) a CDR Hl, a CDR H2, and a CDR H3. In embodiments, the first antigen binding domain and the second antigen binding domain include a CDR LI, a CDR L2, a CDR L3, a CDR Hl, a CDR H2, and a CDR H3. In embodiments, the first antigen binding domain and the second antigen binding domain include a CDR LI, a CDR L2, and a CDR L3. In embodiments, the first antigen binding domain and the second antigen binding domain include a CDR H1, a CDR H2, and a CDR H3.

[0389] In embodiments, the first antigen binding domain includes a CDR LI, a CDR L2, a CDR L3, a CDR Hl, a CDR H2, and a CDR H3. In embodiments, the first antigen binding domain includes a CDR LI, a CDR L2, and a CDR L3. In embodiments, the first antigen binding domain includes a CDR Hl, a CDR H2. and a CDR H3.

[0390] In embodiments, the second antigen binding domain includes (i) a CDR L1, a CDR L2, a CDR L3, a CDR Hl, a CDR H2, and a CDR H3; (ii) a CDR LI, a CDR L2, and a CDR L3; or (iii) a CDR Hl, a CDR H2, and a CDR H3. In embodiments, the second antigen binding domain includes a CDR LI, a CDR L2, a CDR L3, a CDR Hl, a CDR H2, and a CDR H3. In embodiments, the second antigen binding domain includes a CDR LI, a CDR L2, and a CDR L3. In embodiments, the second antigen binding domain includes a CDR H1, a CDR H2, and a CDR H3.

[0391] The antigen binding domains provided herein including embodiments thereof may be any antigen binding domain known and available in the art. Therefore, any of the CDR combinations included in the exemplary list of therapeutic antibodies of Table 1 may be used for the antigen binding domains included in the compositions and complexes provided herein. Forexample, the antigen binding domain may be an scFv and may therefore include the VL and VH or VL CDRs and VH CDRs of any of the antibodies listed in Table 1. Likewise, the antigen binding domain may be a Fab and may therefore include the VL, CL, VH and CHI domains of any of the antibodies listed in Table 1. The antigen binding domain may be a nanobody and may therefore include the VH or VL of any of the antibodies listed in Table 1.

[0392] The antigen binding domains provided herein including embodiments thereof compete for antigen-binding with, specifically bind to the same antigen or epitope as, and / or contain one, more, or all CDRs (or CDRs comprising at least at or about 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 % identity’ to the CDRs), e.g., including a heavy chain CDR 1, 2, and / or 3 and / or a light chain CDR1, 2, and / or 3, of one or more known antibodies, including any commercially available antibody or any of the antibodies listed in Table 1.

[0393] In embodiments, the first antigen binding domain and the second antigen binding domain independently include the CDR LI, the CDR L2, the CDR L3, the CDR Hl, the CDR H2. and the CDR H3 of any one of the antigen binding domains of Table 1. In embodiments, the first antigen binding domain or the second antigen binding domain includes the CDR LI, the CDR L2, the CDR L3, the CDR Hl, the CDR H2, and the CDR H3 of any one of the antigen binding domains of Table 1. In embodiments, the first antigen binding domain includes the CDR LI, the CDR L2, the CDR L3, the CDR Hl, the CDR H2, and the CDR H3 of any one of the antigen binding domains of Table 1. In embodiments, the second antigen binding domain includes the CDR LI, the CDR L2, the CDR L3, the CDR Hl, the CDR H2, and the CDR H3 of any one of the antigen binding domains of Table 1. In embodiments, the first antigen binding domain and the second antigen binding domain include the CDR LI, the CDR L2, the CDR L3, the CDR H1, the CDR H2, and the CDR H3 of the same antigen binding domain of Table 1. In embodiments, the first antigen binding domain and the second antigen binding domain include the CDR LI, the CDR L2, the CDR L3, the CDR Hl, the CDR H2, and the CDR H3 of different antigen binding domains of Table 1.

[0394] In embodiments, the first antigen binding domain and the second antigen binding domain independently include the VH domain and the VL domain of any one of the antigen binding domains of Table 1. In embodiments, the first antigen binding domain or the second antigen binding domain includes the VH domain and the VL domain of any one of the antigenbinding domains of Table 1. In embodiments, the first antigen binding domain includes the VH domain and the VL domain of any one of the antigen binding domains of Table 1. In embodiments, the second antigen binding domain includes the VH domain and the VL domain of any one of the antigen binding domains of Table 1. In embodiments, the first antigen binding domain and the second antigen binding domain include the VH domain and the VL domain of any one of the antigen binding domains of Table 1. In embodiments, the first antigen binding domain and the second antigen binding domain include the VH domain and the VL domain of the same antigen binding domain of Table 1. In embodiments, the first antigen binding domain and the second antigen binding domain include the VH domain and the VL domain of different antigen binding domains of Table 1.

[0395] In embodiments, the first antigen binding domain and the second antigen binding domain independently include the heavy chain and the light chain of any one of the antigen binding domains of Table 1. In embodiments, the first antigen binding domain or the second antigen binding domain includes the heavy chain and the light chain of any one of the antigen binding domains of Table 1. In embodiments, the first antigen binding domain includes the heavy chain and the light chain of any one of the antigen binding domains of Table 1. In embodiments, the second antigen binding domain includes the heavy chain and the light chain of any one of the antigen binding domains of Table 1. In embodiments, the first antigen binding domain and the second antigen binding domain include the heavy chain and the light chain of any one of the antigen binding domains of Table 1. In embodiments, the first antigen binding domain and the second antigen binding domain include the heavy chain and the light chain of the same antigen binding domain of Table 1. In embodiments, the first antigen binding domain and the second antigen binding domain include the heavy chain and the light chain of different antigen binding domains of Table 1.

[0396] In embodiments, the first chemical linker and the second chemical linker are independently a peptide linker. In embodiments, the first chemical linker or the second chemical linker is a peptide linker. In embodiments, the first chemical linker is a peptide linker. In embodiments, the second chemical linker is a peptide linker. In embodiments, the first chemical linker and the second chemical linker are a peptide linker.

[0397] In embodiments, the first chemical linker and the second chemical linker are independently a protease cleavable linker. In embodiments, the first chemical linker or the second chemical linker is a protease cleavable linker. In embodiments, the first chemical linker is a protease cleavable linker. In embodiments, the second chemical linker is a protease cleavable linker. In embodiments, the first chemical linker and the second chemical linker are a protease cleavable linker.

[0398] In embodiments, the first chemical linker and the second chemical linker independently include the sequence of SEQ ID NO:28, SEQ ID NO:49, SEQ ID NO:71, SEQ ID NO:72, or SEQ ID NO: 75. In embodiments, the first chemical linker or the second chemical linker includes the sequence of SEQ ID NO:28. In embodiments, the first chemical linker or the second chemical linker includes the sequence of SEQ ID NO:49. In embodiments, the first chemical linker or the second chemical linker includes the sequence of SEQ ID NO:71. In embodiments, the first chemical linker or the second chemical linker includes the sequence of SEQ ID NO: 72. In embodiments, the first chemical linker or the second chemical linker includes the sequence of SEQ ID NO: 75.

[0399] In embodiments, the first chemical linker includes the sequence of SEQ ID NO:28, SEQ ID NO:49, SEQ ID NO:71, SEQ ID NO:72, or SEQ ID NO:75. In embodiments, the first chemical linker includes the sequence of SEQ ID NO:28. In embodiments, the first chemical linker includes the sequence of SEQ ID NO:49. In embodiments, the first chemical linker includes the sequence of SEQ ID NO:71. In embodiments, the first chemical linker includes the sequence of SEQ ID NO: 72. In embodiments, the first chemical linker includes the sequence of SEQ ID NO: 75.

[0400] In embodiments, the second chemical linker includes the sequence of SEQ ID NO:28, SEQ ID NO:49, SEQ ID NO:71. SEQ ID NO:72, or SEQ ID NO:75. In embodiments, the second chemical linker includes the sequence of SEQ ID NO:28. In embodiments, the second chemical linker includes the sequence of SEQ ID NO:49. In embodiments, the second chemical linker includes the sequence of SEQ ID NO:71. In embodiments, the second chemical linker includes the sequence of SEQ ID NO:72,. In embodiments, the second chemical linker includes the sequence of SEQ ID NO:75.

[0401] In embodiments, the first chemical linker and the second chemical linker include the sequence of SEQ ID NO:28, SEQ ID NO:49, SEQ ID NO:71, SEQ ID NO:72, or SEQ ID NO:75. In embodiments, the first chemical linker and the second chemical linker include the sequence of SEQ ID NO:28. In embodiments, the first chemical linker and the second chemical linker include the sequence of SEQ ID NO: 49. In embodiments, the first chemical linker and the second chemical linker include the sequence of SEQ ID NO:71. In embodiments, the first chemical linker and the second chemical linker include the sequence of SEQ ID NO: 72,. In embodiments, the first chemical linker and the second chemical linker include the sequence of SEQ ID NO:75.

[0402] In embodiments, the first chemical linker and the second chemical linker independently are the sequence of SEQ ID NO:28, SEQ ID NO:49, SEQ ID NO:71, SEQ ID NO:72, or SEQ ID NO:75. In embodiments, the first chemical linker or the second chemical linker is the sequence of SEQ ID NO:28. In embodiments, the first chemical linker or the second chemical linker is the sequence of SEQ ID NO:49. In embodiments, the first chemical linker or the second chemical linker is the sequence of SEQ ID NO:71. In embodiments, the first chemical linker or the second chemical linker is the sequence of SEQ ID NO:72,. In embodiments, the first chemical linker or the second chemical linker is the sequence of SEQ ID NO: 75.

[0403] In embodiments, the first chemical linker is the sequence of SEQ ID NO:28, SEQ ID NO:49, SEQ ID NO:71, SEQ ID NO:72, or SEQ ID NO:75. In embodiments, the first chemical linker is the sequence of SEQ ID NO:28. In embodiments, the first chemical linker is the sequence of SEQ ID NO:49. In embodiments, the first chemical linker is the sequence of SEQ ID NO:71. In embodiments, the first chemical linker is the sequence of SEQ ID NO: 72. In embodiments, the first chemical linker is the sequence of SEQ ID NO:75.

[0404] In embodiments, the second chemical linker is the sequence of SEQ ID NO:28, SEQ ID NO:49, SEQ ID NO:71, SEQ ID NO:72, or SEQ ID NO:75. In embodiments, the second chemical linker is the sequence of SEQ ID NO:28. In embodiments, the second chemical linker is the sequence of SEQ ID NO:49. In embodiments, the second chemical linker is the sequence of SEQ ID NO:71. In embodiments, the second chemical linker is the sequence of SEQ ID NO:72. In embodiments, the second chemical linker is the sequence of SEQ ID NO:75.

[0405] In embodiments, the first chemical linker and the second chemical linker are the sequence of SEQ ID NO:28, SEQ ID NO:49, SEQ ID NO:71, SEQ ID NO:72, or SEQ ID NO:75. In embodiments, the first chemical linker and the second chemical linker are the sequence of SEQ ID NO:28. In embodiments, the first chemical linker and the second chemical linker are the sequence of SEQ ID NO:49. In embodiments, the first chemical linker and the second chemical linker are the sequence of SEQ ID NO:71. In embodiments, the first chemical linker and the second chemical linker are the sequence of SEQ ID NO:72. In embodiments, the first chemical linker and the second chemical linker are the sequence of SEQ ID NO:75.IV. Polypeptides including a cytokine domain, a cytokine receptor domain and / or a cytokine enhancer domain

[0406] The polypeptides (e.g., a polypeptide including a CD16 domain, a CD32 domain, or a CD64 domain) provided herein including embodiments thereof can further include a cytokine domain. Thus, in embodiments, the polypeptide provided herein including embodiments thereof further includes a cytokine domain bound to the Fc gamma receptor domain through a first chemical linker. In embodiments, the cytokine domain is bound to the N-terminus of the Fc gamma receptor domain. In embodiments, the cytokine domain is bound to the C -terminus of the Fc gamma receptor domain.

[0407] In embodiments, the polypeptide provided herein including embodiments thereof further includes a cytokine receptor domain bound to the Fc gamma receptor domain through a second chemical linker. In embodiments, the cytokine receptor domain is bound to the N-terminus of the Fc gamma receptor domain. In embodiments, the cytokine receptor domain is bound to the C-terminus of the Fc gamma receptor domain.

[0408] In embodiments, from the N-terminus to the C-terminus the polypeptide includes a cytokine domain, a first chemical linker, a Fc gamma receptor domain, a second chemical linker and a cytokine receptor domain. In embodiments, the cytokine domain is an IL-2 domain, the Fc gamma receptor domain is a CD 16 domain, and the cytokine receptor domain is a IL-2RA domain. In a further embodiment, the first chemical linker is a protease cleavable linker.

[0409] In embodiments, the cytokine domain is an IL-2 domain, the Fc gamma receptor domain is a CD 16 domain, and the cytokine receptor domain is an IL-2RB domain. In a furtherembodiment, the first chemical linker is a protease cleavable linker. In one further embodiment, the polypeptide includes the sequence of SEQ ID NO: 157. In one further embodiment, the polypeptide includes the sequence of SEQ ID NO: 266.

[0410] In embodiments, the cytokine domain is an IL-15 domain, the Fc gamma receptor domain is a CD 16 domain, and the cytokine receptor domain is a IL-2RB domain. In a further embodiment, the first chemical linker is a protease cleavable linker. In one further embodiment, the polypeptide includes the sequence of SEQ ID NO: 155. In one further embodiment, the polypeptide includes the sequence of SEQ ID NO: 264.

[0411] The polypeptides provided herein may include a cytokine enhancer domain as described herein (e.g., a sushi domain which is an extracellular domain of IL-15RA). The cytokine enhancer domain (e.g., sushi domain) may bind to the cytokine domain (e.g., IL15 domain) covalently (through disulfide linkage) or non-covalently thereby forming a complex also referred to herein as super agonist. Without being bound to any particular scientific theory', the stability and / or affinity of the cytokine domain (e.g.. IL- 15) is increased and its entropy is reduced when it forms part of a super agonist (i.e., is bound to the sushi domain) relative to IL-15 alone (not bound to the sushi domain). IL- 15 bound covalently or non-covalently to a sushi domain has increased stability resulting in improved binding to its respsective receptors (IL-2RB and IL-2RG).

[0412] Thus, in embodiments, the polypeptide provided herein including embodiments thereof further includes a cytokine enhancer domain. The cytokine enhancer domain may be bound to the Fc gamma receptor domain through a chemical linker and the chemical linker may be a protease cleavable linker.

[0413] In embodiments, the cytokine enhancer domain is bound to the N-terminus of the Fc gamma receptor domain. In embodiments, the cytokine enhancer domain is bound to the C-terminus of the Fc gamma receptor domain. In embodiments, the cytokine enhancer domain is a sushi domain. In embodiments, the cytokine enhancer domain includes the sequence of SEQ ID NO: 150. In embodiments, the cytokine enhancer domain is the sequence of SEQ ID NO: 150.

[0414] In embodiments, from the N-terminus to the C-terminus the polypeptide includes a cytokine domain, a first chemical linker, a Fc gamma receptor domain, a second chemical linkerand a cytokine enhancer domain. In embodiments, the cytokine domain is an IL- 15 domain, the Fc gamma receptor domain is a CD16 domain, and the cytokine enhancer domain is a sushi domain. In a further embodiment, the first chemical linker is a protease cleavable linker. In one further embodiment, the polypeptide includes the sequence of SEQ ID NO: 154. In one further embodiment, the polypeptide includes the sequence of SEQ ID NO: 263.

[0415] In embodiments, from the N-terminus to the C-terminus the polypeptide includes a cytokine domain, a first chemical linker, a cytokine enhancer domain, a second linker, a Fc gamma receptor domain, a third chemical linker and a cytokine receptor domain. In embodiments, the cytokine domain is an IL-15 domain, the cytokine enhancer domain is a sushi domain, the Fc gamma receptor domain is a CD16 domain, and the cytokine receptor domain is a IL-2RB domain. In a further embodiment, the second chemical linker is a protease cleavable linker. In one further embodiment, the polypeptide includes the sequence of SEQ ID NO: 156. In one further embodiment, the polypeptide includes the sequence of SEQ ID NO: 265.

[0416] In emodiments. the cytokine domain is an IL -2 domain, or an IL- 15 domain domain. In emodiments, the cytokine domain is an IL-2 domain. In emodiments, the cytokine domain is an an IL- 15 domain.

[0417] In embodiments, the cytokine domain is an IL-2 domain. In some embodiments, the IL-2 domain includes the amino acid sequence of SEQ ID NO: 86. In some embodiments, the IL-2 domain comprises an amino acid sequence that has at least 90%. 91%. 92%. 93%. 94%. 95%, 96%, 97%, 98%, or 99% amino acid sequence identity to the amino acid sequence of SEQ ID NO: 86 across the whole sequence or a portion of the sequence (e.g. a 50, 75, 100, or 125 continuous amino acid portion). In embodiments, the cytokine domain is an IL- 15 domain. In some embodiments, the IL-15 domain comprises the amino acid sequence of SEQ ID NO: 87. In some embodiments, the IL-15 domain comprises an amino acid sequence that has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% amino acid sequence identity to the amino acid sequence of SEQ ID NO: 87 across the whole sequence or a portion of the sequence (e.g. a 50, 75, 100, or 125 continuous amino acid portion). Any cytokine domain including at least two receptor binding sites is contemplated for the invention provided herein. An IL-2 domain or IL-15 domain as provided herein includes at least 40 amino acid residues corresponding to 40 consecutive amino acid residues of IL-2 or IL-15, respectively. In embodiments, the cytokinedomain is between 100 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 110 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 120 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 130 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 140 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 150 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 160 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 170 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 180 and 500 ammo acid residues in length. In embodiments, the cytokine domain is between 190 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 200 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 250 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 300 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 350 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 400 and 500 amino acid residues in length. In embodiments, the cytokine domain is between 450 and 500 amino acid residues in length. In embodiments, the cytokine domain is 100, 110, 120, 130, 140. 150, 160, 170, 180, 190. 200, 250. 300, 350, 400, 450, or 500 amino acid residues in length. In further embodiments, the 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 250, 300, 350, 400, 450, or 500 amino acid residues correspond to 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 250, 300, 350, 400, 450, or 500 consecutive ammo acid residues of IL-2 or IL-15, respectively. In embodiments, the cytokine domain is 133 amino acid residues in length. In further embodiments, the 133 amino acid residues correspond to 133 consecutive amino acid residues of IL-2.

[0418] In embodiments, the cytokine domain includes the sequence of SEQ ID NO: 86. In embodiments, the cytokine domain includes the sequence of SEQ ID NO: 87.

[0419] In embodiments, the cy tokine receptor domain is an IL-2R domain, or an IL-15R domain. In embodiments, the cytokine receptor domain is an IL-2R domain. In embodiments, the cytokine receptor domain is an IL-15R domain.

[0420] The cytokine receptor domain may be an IL-2Ra domain. In embodiments, the cytokine receptor domain includes the amino acid sequence of SEQ ID NO: 88. Inembodiments, the cytokine receptor domain includes an amin...

Claims

1. WHAT IS CLAIMED IS:

1. A polypeptide comprising a Fc gamma receptor domain, wherein said Fc gamma receptor domain is a CD 16 domain comprising a cysteine at a position corresponding to amino acid position 106 of CD 16.

2. The polypeptide of claim 1, wherein said CD 16 domain comprises an amino acid sequence corresponding to amino acids 8-174 of CD16.

3. The polypeptide of claim 1, wherein said CD 16 comprises the sequence of SEQ ID NO:4 or SEQ ID NO:5.

4. A polypeptide comprising a Fc gamma receptor domain, wherein said Fc gamma receptor domain is a CD32 domain comprising a cysteine at a position corresponding to amino acid position 121 of CD32.

5. The polypeptide of claim 4, wherein said CD32 domain comprises an amino acid sequence corresponding to amino acids 32-207 of CD32.

6. The polypeptide of claim 4, wherein said CD32 comprises the sequence of SEQ ID NO:6.

7. A polypeptide comprising a Fc gamma receptor domain, wherein said Fc gamma receptor domain is a CD64 domain comprising a cysteine at a position corresponding to amino acid position 102 of CD64.

8. The polypeptide of claim 7, wherein said CD64 domain comprises an amino acid sequence corresponding to amino acids 16-187 of CD64.

9. The polypeptide of claim 7, wherein said CD64 comprises the sequence of SEQ IDNO:83.

10. The polypeptide of any one of claims 1, 4, or 7, further comprising a first antigen binding domain bound to said Fc gamma receptor domain through a first chemical linker.

11. The polypeptide of claim 10, wherein said first antigen binding domain is bound to the N-terminus of said Fc gamma receptor domain.

12. The polypeptide of claim 10, wherein said first antigen binding domain is bound to the C-terminus of said Fc gamma receptor domain.

13. The polypeptide of claim 10, further comprising a second antigen binding domain bound to said Fc gamma receptor domain through a second chemical linker.

14. The polypeptide of claim 13, wherein said second antigen binding domain is bound to the N-terminus of said Fc gamma receptor domain.

15. The polypeptide of claim 13, wherein said second antigen binding domain is bound to the C-terminus of said Fc gamma receptor domain.

16. The polypeptide of claim 10, wherein said first antigen binding domain and said second antigen binding domain are independently an antibody, an antibody domain or an antibody variant.

17. The polypeptide of claim 13, wherein said first antigen binding domain and said second antigen binding domain are independently a variable light (VL) domain or a variable heavy (VH) domain.

18. The polypeptide of claim 13, wherein said first antigen binding domain is a variable light domain and said second antigen binding domain is a variable heavy domain.

19. The polypeptide of claim 13, wherein said first antigen binding domain is a variable heavy domain and said second antigen binding domain is a variable light domain.

20. The polypeptide of claim 10 or 13, wherein said first antigen binding domain is attached to the N-terminus of said Fc gamma receptor domain and wherein said second antigen binding domain is attached to the C-terminus of said Fc gamma receptor domain.

21. The polypeptide of claim 10 or 13, wherein said first antigen binding domain and said second antigen binding domain are independently an scFv.

22. The polypeptide of claim 10 or 13, wherein said first antigen binding domain and said second antigen binding domain are independently a CD3 binding domain.

23. The polypeptide of claim 10 or 13, wherein said first antigen binding domain and said second antigen binding domain independently comprise the sequence of SEQ ID NO: 18, SEQ ID NO:23, or SEQ IDNO:42.

24. The polypeptide of claim 10 or 13, wherein said first antigen binding domain and said second antigen binding domain are independently a cancer antigen binding domain.

25. The polypeptide of claim 10 or 13, wherein said first antigen binding domain and said second antigen binding domain independently comprise (i) a CDR LI, a CDR L2, a CDR L3, a CDR Hl, a CDR H2, and a CDR H3; (ii) a CDR LI, a CDR L2, and a CDR L3; or (iii) a CDR Hl, a CDR H2, and a CDR H3.

26. The polypeptide of claim 10 or 13, wherein said first antigen binding domain and said second antigen binding domain independently comprise the CDR LI, the CDR L2, the CDR L3, the CDR Hl, the CDR H2, and the CDR H3 of any one of the antigen binding domains of Table 1.

27. The polypeptide of claim 10 or 13, wherein said first antigen binding domain and said second antigen binding domain independently comprise the VH domain and the VL domain of any one of the antigen binding domains of Table 1.

28. The polypeptide of claim 10 or 13, wherein said first antigen binding domain and said second antigen binding domain independently comprise the heavy chain and the light chain of any one of the antigen binding domains of Table 1.

29. The polypeptide of claim 1, further comprising a cytokine domain bound to said Fc gamma receptor domain through a first chemical linker.

30. The polypeptide of claim 29, wherein said cytokine domain is bound to the N-terminus of said Fc gamma receptor domain.

31. The polypeptide of claim 29, wherein said cytokine domain is bound to the C-terminus of said Fc gamma receptor domain.

32. The polypeptide of claim 1 or 31, further comprising a cytokine receptor domain bound to said Fc gamma receptor domain through a second chemical linker.

33. The polypeptide of claim 32, wherein said cytokine receptor domain is bound to the N-terminus of said Fc gamma receptor domain.

34. The polypeptide of claim 32, wherein said cytokine receptor domain is bound to the C-terminus of said Fc gamma receptor domain.

35. The polypeptide of claim 29, wherein said cytokine domain is an IL-2 domain, an IL-15 domain or a CXCL12 domain.

36. The polypeptide of claim 35, wherein said cytokine domain comprises the sequence of SEQ ID NO:86.

37. The polypeptide of claim 29, wherein said cytokine receptor domain is an IL-2R domain, an IL-15R domain or a CXCL12R domain.

38. The polypeptide of claim 37, wherein said cytokine receptor domain comprises the sequence of SEQ ID NO: 88, SEQ ID NO: 89 or SEQ ID NO:261.

39. The polypeptide of any one of claims 1, 4 or 7, further comprising a recombinant cytokine receptor binding protein bound to said Fc gamma receptor domain through a first chemical linker,wherein said recombinant cytokine receptor binding protein comprises:(i) an IL-2 domain comprising an IL-2 receptor a binding site, an IL-2 receptor p binding site and an IL-2 receptor binding site;(ii) an IL-2 receptor a domain that specifically binds to said IL-2 receptor a binding site; and(iii) an occlusion domain positioned to sterically hinder binding of said IL-2 receptor 0 binding site to an IL-2 receptor 0 domain; wherein the C-terminus of said IL-2 domain is bound to the N-terminus of said occlusion domain through a cleavable linker; andthe C-terminus of said occlusion domain is bound to the N-terminus of said IL2 receptor a domain through a third chemical linker.

40. The polypeptide of claim 39, wherein said occlusion domain is an anti-CD3 nanobody.

41. The polypeptide of claim 39 or 40, further comprising an antigen binding domain bound to said Fc gamma receptor domain through a second chemical linker.

42. The polypeptide of 41, wherein said antigen binding domain is an anti-CD28 antibody domain.

43. The polypeptide of claim 42, wherein said recombinant cytokine receptor binding protein and said antigen binding domain are bound on opposite ends of said Fc gamma receptor domain.

44. The polypeptide of claim 43, wherein said antigen binding domain is a cancer antigen binding domain.

45. The polypeptide of claim 44, wherein said antigen binding domain comprises (i) a CDR LI, a CDR L2, a CDR L3, a CDR Hl, a CDR H2, and a CDR H3; (ii) a CDR LI, a CDR L2, and a CDR L3; or (iii) a CDR Hl, a CDR H2, and a CDR H3.

46. The polypeptide of claim 45, wherein said antigen binding domain comprises the CDR LI, the CDR L2, the CDR L3, the CDR Hl, the CDR H2, and the CDR H3 of any one of the antigen binding domains of Table 1.

47. The polypeptide of claim 46, wherein said first antigen binding domain and said second antigen binding domain independently comprise the VH domain and the VL domain of any one of the antigen binding domains of Table 1.

48. The polypeptide of claim 47, wherein said antigen binding domain comprises the heavy chain and the light chain of any one of the antigen binding domains of Table 1.

49. The polypeptide of claim 48, wherein said first chemical linker and said second chemical linker are independently a peptide linker.

50. The polypeptide of claim 49, wherein said first chemical linker and said second chemical linker are independently a protease cleavable linker.

51. The polypeptide of claim 50, wherein said first chemical linker and said second chemical linker independently comprise the sequence of SEQ ID NO:28, SEQ ID NO:49, SEQ ID NO:71, SEQ ID NO:72, or SEQ ID NO:75..

52. The polypeptide of any one of claims 1, 4 or 7, further comprising a a single chain polypeptide bound to said Fc gamma receptor domain through a first chemical linker, wherein said single chain polypeptide comprises:(i) a first protein dimerizing domain bound to a first ligand binding domain through a third chemical linker; and(ii) a second protein dimerizing domain bound to said first ligand binding domain through a fourth chemical linker;wherein said first protein dimerizing domain is capable of binding to said second protein dimerizing domain to form a second ligand binding domain.

53. The polypeptide of claim 52, wherein said first ligand binding domain is a nanobody.

54. The polypeptide of claim 53, wherein said first protein dimerizing domain is an antibody light chain55. The polypeptide of claim 54, wherein said second protein dimerizing domain is an antibody heavy chain.

56. The polypeptide of claim 55, wherein said second ligand binding domain is a Fab domain.

57. The polypeptide of claim 56, wherein said first chemical linker, said third chemical linker and said fourth chemical linker are independently a peptidyl linker.

58. The polypeptide of claim 57, wherein said first chemical linker, said third chemical linker and said fourth chemical linker are independently a protease cleavable linker.

59. The polypeptide of claim 58, further comprising an antigen binding domain bound to said Fc gamma receptor domain through a second chemical linker.

60. The polypeptide of claim 59, wherein said antigen binding domain is a cancer antigen binding domain.

61. The polypeptide of claim 60, wherein said antigen binding domain comprises (i) a CDR LI, a CDR L2, a CDR L3, a CDR Hl, a CDR H2, and a CDR H3; (ii) a CDR LI, a CDR L2, and a CDR L3; or (iii) a CDR Hl, a CDR H2, and a CDR H3.

62. The polypeptide of claim 61, wherein said antigen binding domain comprises the CDR LI, the CDR L2, the CDR L3, the CDR Hl, the CDR H2, the CDR H3 of any one of the antigen binding domains of Table 1.

63. The polypeptide of claim 62, wherein said first antigen binding domain and said second antigen binding domain independently comprise the VH domain and the VL domain of any one of the antigen binding domains of Table 1.

64. The polypeptide of claim 63, wherein said antigen binding domain comprises the heavy chain and the light chain of any one of the antigen binding domains of Table 1.

65. A covalent complex comprising:(i) a polypeptide of any one of claims 1, 4 or 7; and(ii) an Fc domain comprising a second cysteine;wherein said polypeptide is covalently bound to said Fc domain through a disulfide linkage between (a) said cysteine at a position corresponding to amino acid position 106 of CD16, (b) said cysteine at a position corresponding to amino acid position 121 of CD32 or (c) said cysteine at a position corresponding to amino acid position 102 of CD64 and said second cysteine.

66. The covalent complex of claim 65, wherein said second cysteine is at a position corresponding to amino acid position 330 of the Fc domain of IgGl.

67. The covalent complex of claim 66, wherein said Fc domain is bound to an antigen binding domain.

68. The covalent complex of claim 67, wherein said antigen binding domain is an antibody, an antibody domain or an antibody variant.

69. The covalent complex of claim 68, wherein said antigen binding domain is a Fab, an scFv, or a nanobody.

70. The covalent complex of claim 69, wherein said antigen binding domain is a cancer antigen binding domain.

71. The covalent complex of claim 70, wherein said antigen binding domain comprises (i) a CDR LI, a CDR L2, a CDR L3, a CDR Hl, a CDR H2, and a CDR H3; (ii) a CDR LI, a CDR L2, and a CDR L3; or (iii) a CDR Hl, a CDR H2, and a CDR H3.

72. The covalent complex of claim 71, wherein said antigen binding domain comprises the CDR LI, the CDR L2, the CDR L3, the CDR Hl, the CDR H2, the CDR H3 of any one of the antigen binding domains of Table 1.

73. The covalent complex of claim 72, wherein said first antigen binding domain and said second antigen binding domain independently comprise the VH domain and the VL domain of any one of the antigen binding domains of Table 1.

74. The covalent complex of claim 73, wherein said antigen binding domain comprises the heavy chain and the light chain of any one of the antigen binding domains of Table 1.

75. The covalent complex of claim 73, wherein said Fc domain is bound to an Fc receptor on a cell.

76. The covalent complex of claim 75, wherein said cell is an effector T cell.

77. The covalent complex of claim 76, wherein said antigen binding domain binds to a cancer cell.

78. A recombinant nucleic acid sequence encoding the polypeptide of any one of claims 1, 4 or 7.

79. An expression vector comprising the nucleic acid sequence of claim 78.

80. A cell comprising the expression vector of claim 79.

81. A pharmaceutical composition comprising the polypeptide of any one of claims 1, 4 or 7 and a pharmaceutically acceptable excipient.

82. A method of treating cancer in a subject in need thereof, said method comprising administering to said subject a therapeutically effective amount of the polypeptide of any one of claims 1, 4 or 7, thereby treating cancer in said subject.

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