De novo designed binders targeting the tumor associated antigens her2, ceacam5, trop2, BCMA, FAP, and ROR1

Abstract

Polypeptide binders of tumor associated antigens HER2, CEACAM5, TROP2, BCMA, FAP, and ROR1 are provided, fusion proteins thereof, conjugates thereof, and methods for their use.

Description

[0001]UW 49862.01US1 De Novo Designed Binders Targeting the Tumor Associated Antigens HER2, CEACAM5, TROP2, BCMA, FAP, and ROR1 Federal Funding Statement This invention was made with government support under Grant Nos.1U19AG065156 and 1U19AG065156-01 and 5U19AG065156-03, awarded by the National Institute on Aging and Grant Nos. R01 CA 240339-01 and R01CA240339, awarded by the National Institute of Health - National Cancer Institute. The government has certain rights in the invention. Sequence Listing Statement A computer readable form of the Sequence Listing is filed with this application by electronic submission and is incorporated into this application by reference in its entirety. The Sequence Listing is contained in the file created on June 10, 2025 having the file name “24- 0749-WO.xml” and is 146,392 bytes in size. Background Multiple receptors are overexpressed on cancer cells including Receptor tyrosine- protein kinase erbB-2 (HER2), Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), Tumor-associated calcium signal transducer 2 (TROP2), Inactive tyrosine- protein kinase transmembrane receptor ROR1 (ROR1), and Tumor necrosis factor receptor superfamily member 17 (BCMA). These receptors are highly expressed on various cancer cells and have no or low expression in most healthy tissues, and thus are targets for tumor treatment, and for targeted drug delivery and diagnostic imaging. However, current therapies targeting these receptors are inadequate. Summary In a first aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:1-10, and wherein the polypeptide binds to Receptor tyrosine-protein kinase erbB-2 (HER2). In some embodiments, relative to the reference sequence, residue 29 is L, residue 30 is A, residue 33 is Y, residue 46 is D, residue 55 is A, and residue 56 is R. In other embodiments, substitutions relative to the reference sequence are selected from allowable amino acids listed in Table 2. In further embodiments, relative to the reference sequence, at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or all 19 interface residues are conserved. In some embodiments, relative to the reference sequence, at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or all 14 core residues are conserved. In another embodiment relative to the reference sequence, one or more residues are substituted with a C or a K residue. In a second aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:11-14, and wherein the polypeptide binds to carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5). In some embodiments, relative to the reference sequence, residue 15 is V, residue 51 is A, and residue 55 is F. In other embodiments, substitutions relative to the reference sequence are selected from allowable amino acids listed in Table 4. In further embodiments, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or all 16 interface residues are conserved. In some embodiments, relative to the reference sequence, at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or all 10 core residues are conserved. In one embodiment, relative to the reference sequence, one or more residues are substituted with a C or a K residue. In a third aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:15-26, and wherein the polypeptide binds to Tumor- associated calcium signal transducer 2 (TROP2). In some embodiments, relative to the reference sequence, residues noted as key residues are conserved. In other embodiments, substitutions relative to the reference sequence are conservative amino acid substitutions. In further embodiments, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues are conserved. In some embodiments, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved. In one embodiment, relative to the reference sequence, one or more residues are substituted with a C or a K residue. In a third aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:27-29, and wherein the polypeptide binds to Tumor necrosis factor receptor superfamily member 17 (BCMA). In some embodiments, relative to the reference sequence, residues noted as key residues are conserved. In other embodiments, substitutions relative to the reference sequence are conservative amino acid substitutions. In further embodiments, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues are conserved. In other embodiments, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved. In one embodiment, relative to the reference sequence, one or more residues are substituted with a C or a K residue. In a fourth aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:30-35, and wherein the polypeptide binds to Prolyl endopeptidase / Fibroblast Activation Protein (FAP). In some embodiments, relative to the reference sequence, residues noted as key residues are conserved (i.e., identical); or wherein the polypeptide comprises the amino acid sequence of SEQ ID NO:36-37. In further embodiments, substitutions relative to the reference sequence are conservative amino acid substitutions. In other embodiments, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues are conserved. In some embodiments, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved. In one embodiment, relative to the reference sequence, one or more residues are substituted with a C or a K residue. In a fifth aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:38-54, and wherein the polypeptide binds to Inactive tyrosine-protein kinase transmembrane receptor ROR1 (ROR1). In some embodiments, relative to the reference sequence, residues noted as key residues are conserved; or the polypeptide comprises the amino acid sequence of SEQ ID NO:55-58. In other embodiments, substitutions relative to the reference sequence are conservative amino acid substitutions. In further embodiments, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues are conserved. In some embodiments, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved. In one embodiment, relative to the reference sequence, one or more residues are substituted with a C or a K residue. The disclosure also provides fusion proteins, comprising (a) the polypeptide of any embodiment or combination of embodiments of the first, second, third, fourth, or fifth aspects of the disclosure; and (b) one or more functional domains at the N-terminus and / or at the C- terminus of the polypeptide. In one embodiment the one or more functional domains comprises a domain for half-life extension, optionally wherein the domain for half-life extension comprises an albumin domain. In other embodiments, the one or more functional domains comprises at least a second polypeptide of embodiment or combination of embodiments of the first, second, third, fourth, or fifth aspects of the disclosure that bind to a different target than the first polypeptide, to provide a heterofunctional binder. The disclosure also provides conjugates, comprising (a) the polypeptide or fusion protein of any embodiment or combination of embodiments of the first, second, third, fourth, or fifth aspects of the disclosure; and (b) an anti-tumor therapeutic covalently linked to the polypeptide or fusion protein. In some embodiments, the anti-tumor therapeutic is selected from the group consisting of angiogenesis inhibitors, tubulin inhibitors, topoisomerase inhibitors, DNA damage inducers, immune checkpoint inhibitors, mTOR inhibitors, PI3K inhibitors, histone deacetylase inhibitors, and Hedgehog pathway blockers. The disclosure also provides (a) nucleic acids encoding the polypeptide or fusion protein of any embodiment or combination of embodiments herein, (b) expression vectors comprising the nucleic acids operatively linked to a suitable control sequence, such as a promoter, (c) host cells comprising the polypeptide, fusion protein, nucleic acid, or expression vector of any embodiment or combination of embodiments herein, and (d) pharmaceutical compositions, comprising (i) the polypeptide, fusion protein, conjugate, nucleic acid, expression vector, and / or host cell of any embodiment or combination of embodiments herein; and (ii) a pharmaceutically acceptable carrier. The disclosure also provides methods for treating a tumor, comprising administering to a subject in need thereof an amount effective to treat the tumor of the polypeptide, fusion protein, conjugate, nucleic acid, expression vector, host cell, and / or pharmaceutical composition of any embodiment or combination of embodiments herein. The disclosure further provides methods for imaging a tumor, comprising administering to a subject in need thereof a detectable polypeptide, fusion protein, or conjugate of any embodiment or combination of embodiments herein under conditions suitable to bind a target of the polypeptide on the tumor, and detecting binding of the polypeptide, fusion protein, or conjugate to the tumor. Description of the Figures Figure 1. Cell viability of breast adenocarcinoma cell lines MCF7 (HER2-negative) and SKBR3 (HER2-positive) incubated with a HER2 minibinder (SEQ ID 6) conjugated to the potent cytotoxin MMAE through a site-specific cysteine. The HER2 minibinder drug conjugate shows potent toxicity (LC50600 pM) against the HER2 expressing cell line, SKBR3 and no toxicity against the cell line lacking HER2 expression, MCF7. This demonstrates the high target selectivity of the minibinder that makes it suitable for use in targeted drug delivery or detection. Figure 2. Alignment of SEQ ID NO:1-10 (from top to bottom). Stars at the bottom of the figure represent conserved residues, while colons or periods represent conservative amino acid differences. Figure 3. Alignment of SEQ ID NO:11-14 (from top to bottom). Stars at the bottom of the figure represent conserved residues, while colons represent conservative amino acid differences. Detailed Description All references cited are herein incorporated by reference in their entirety. Within this application, unless otherwise stated, the techniques utilized may be found in any of several well-known references such as: Molecular Cloning: A Laboratory Manual (Sambrook, et al., 1989, Cold Spring Harbor Laboratory Press), Gene Expression Technology (Methods in Enzymology, Vol.185, edited by D. Goeddel, 1991. Academic Press, San Diego, CA), “Guide to Protein Purification” in Methods in Enzymology (M.P. Deutshcer, ed., (1990) Academic Press, Inc.); PCR Protocols: A Guide to Methods and Applications (Innis, et al. 1990. Academic Press, San Diego, CA), Culture of Animal Cells: A Manual of Basic Technique, 2ndEd. (R.I. Freshney.1987. Liss, Inc. New York, NY), Gene Transfer and Expression Protocols, pp.109-128, ed. E.J. Murray, The Humana Press Inc., Clifton, N.J.), Dang, B. et al. SNAC-tag for sequence-specific chemical protein cleavage. Nat. Methods 16, 319–322 (2019), and the Ambion 1998 Catalog (Ambion, Austin, TX). As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. As used herein, the amino acid residues are abbreviated as follows: alanine (Ala; A), asparagine (Asn; N), aspartic acid (Asp; D), arginine (Arg; R), cysteine (Cys; C), glutamic acid (Glu; E), glutamine (Gln; Q), glycine (Gly; G), histidine (His; H), isoleucine (Ile; I), leucine (Leu; L), lysine (Lys; K), methionine (Met; M), phenylalanine (Phe; F), proline (Pro; P), serine (Ser; S), threonine (Thr; T), tryptophan (Trp; W), tyrosine (Tyr; Y), and valine (Val; V). Any N-terminal methionine residue in any polypeptide of the disclosure may be present or may be deleted. In all embodiments of the polypeptides disclosed herein, 1, 2, 3, 4, or 5 residues may be deleted from the N-terminus and / or the C-terminus of the polypeptide while retaining activity. All embodiments of any aspect of the disclosure can be used in combination, unless the context clearly dictates otherwise. Unless the context clearly requires otherwise, throughout the description and the claims, the words ‘comprise’, ‘comprising’, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. Words using the singular or plural number also include the plural and singular number, respectively. Additionally, the words “herein,” “above,” and “below” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of the application. The description of embodiments of the disclosure is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. While the specific embodiments of, and examples for, the disclosure are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the disclosure, as those skilled in the relevant art will recognize. In a first aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:1-10, and wherein the polypeptide binds to Receptor tyrosine-protein kinase erbB-2 (HER2). As described below, the inventors developed computer designed binding proteins called “minibinders” against multiple receptors overexpressed on cancer cells including Receptor tyrosine-protein kinase erbB-2 (HER2), Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), Tumor-associated calcium signal transducer 2 (TROP2), Inactive tyrosine-protein kinase transmembrane receptor ROR1 (ROR1), and slightly larger binders against Tumor necrosis factor receptor superfamily member 17 (BCMA). These receptors are highly expressed on various cancer cells and have no or low expression in most healthy tissues. These de novo designed binders have enhanced tumor penetration due to their small size relative to antibodies targeting the receptors, and are highly thermostable allowing radio labeling at temperatures above 80°C , which is not possible with most biologics. The target specificity and unique target binding modes of these minibinders makes them useful for treating tumors on their own, and for targeted drug delivery and diagnostic imaging. In some cases the target binding mode of the minibinders can induce receptor mediated endocytosis, thus further facilitating the potential for their use in treating tumors and as drug delivery vehicles. The de novo designed minibinders targeting Her2 are around 7 kDa and have low picomolar affinities as determined by octet BLI. Additionally, site saturation mutagenesis (SSM) of the binders displayed on yeast revealed the functional tolerance of all possible single point mutations, of which combinations of mutations can be selected to enhance function (binding affinity, binding specificity, stability, solubility, or cysteine conjugation). Size-exclusion chromatography (SEC) showed the designs are well-behaved monodisperse proteins, and cell binding assays show the designs can target human cells expressing the Her2 receptor, verifying they can be used for diagnostic imaging of her2 positive cancers. The binders can also be used for targeted delivery of cytotoxic drugs to cancer cells expressing her2 by (for example) conjugation of a cytotoxic drug (small molecules, nucleic acids, or proteins) or radionuclide, to site specific cysteines on the binders. Exemplary such cytotoxic drugs are described in detail below. Conjugation of the potent cytotoxin MMAE to the binders is capable of killing cancer cells expressing Her2 with an LC50 of 600 pM in in vitro experiments while sparing non- expressing cells. Variants containing cysteine and / or defined number of lysines are described herein for payload conjugation. Additionally, variants of the binding interface have been made that span almost three orders of magnitude affinity from 10 pM (her2_cb_0672; SEQ ID NO:2, as well as the designs listed as SEQ ID NO:3-7) to 200 pM (her2_cb_0672_15C_45H; SEQ ID NO:9) to 18 nM (her2_cb_0672_15C_33H; SEQ ID NO:8) to 80 nM (her2_cb_0672_15C_52H; SEQ ID NO:10). The amino acid sequences of SEQ ID NO:1-10 are provided in Table 1. In one embodiment, the polypeptide comprises an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:1-10, wherein the polypeptide binds to HER2. In another embodiment, the polypeptide comprises an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:1-10, wherein the polypeptide binds to HER2. In a further embodiment, the polypeptide comprises an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:1-10, wherein the polypeptide binds to HER2. In one embodiment, the polypeptide comprises an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:1-10, wherein the polypeptide binds to HER2. Table 1. HER2 Targeting Sequences In other embodiments, relative to the reference sequence, residue 29 is L, residue 30 is A, residue 33 is Y, residue 46 is D, residue 55 is A, and residue 56 is R. Each of these residues is present at a binding interface with HER2, and were identified as being important for high affinity binding, although conservative mutations can be made that retain high affinity binding. In a further embodiment, substitutions relative to the reference sequence are selected from allowable amino acids listed in Table 2. Allowable amino acid residues, as determined by SSM studies, are shown in the far right column of Table 2. Table 2 In another embodiment, relative to the reference sequence, at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or all 19 interface residues present at a binding interface with Her2 are conserved. Interface residues with Her2 are denoted by “I” in the fourth column of Table 2. In a further embodiment, relative to the reference sequence, at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or all 14 core residues are conserved. Core residues are denoted by “C” in the fourth column of Table 2. In one embodiment, relative to the reference sequence, one or more residues are substituted with a C or a K residue. As shown herein, substitution with C or K can facilitate conjugation of other moieties (such as cytotoxic therapeutics) to the polypeptide. In some embodiments, the one or more C or K residue can be substituted for a surface residue, as denoted by an “S” in column 4 of Table 2. In another embodiment, substitutions relative to the reference sequence are conservative amino acid substitutions. In another embodiment, the polypeptide comprises an amino acid sequence at least 80%, 85%, 90%, 95%, 98%, or 100% identical to the amino acid of SEQ ID NO:59, wherein residues in parentheses are optional residues at the position, and X1, X2, X3, X4, X5, X6, X7, and X8 may be any amino acid. The genus of SEQ ID NO:59 is based on a sequence alignment of the polypeptides of SEQ ID NO:1-10. See Figure 2. SV(D / E)EKIEELYEKVK(X1)LAK(K / R)GDREATA(K / R)VLAE(L / M)(H / Y)R LA(X2)(X3)(X4)GD(X5)(K / R)(F / V)(X6)DRL(X7)EA(H / Y / F)(K / Q / N)(X8)A RENLS (SEQ ID NO:59) In another embodiment, X1, X2, X3, X4, X5, X6, X7, and X8 in SEQ ID NO:59 are defined as follows: X1: C or E; X2: V or Q; X3: Q, A, or E; X4: S, R, or K; X5: D, P, or A; X6: F, H, or I; X7: D, V, or G; X8: T, I, or K. In a second aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:11-14, and wherein the polypeptide binds to carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5). The amino acid sequences of SEQ ID NO:11-14 are provided in Table 3. In one embodiment, the polypeptide comprises an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:11-14, wherein the polypeptide binds to CEACAM5. In another embodiment, the polypeptide comprises an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:11-14, wherein the polypeptide binds to CEACAM5. In a further embodiment, the polypeptide comprises an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:11-14, wherein the polypeptide binds to CEACAM5. In one embodiment, the polypeptide comprises an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:11-14, wherein the polypeptide binds to CEACAM5. In various embodiments, relative to the reference sequence, residue 15 is V, residue 51 is A, and residue 55 is F. Each of these residues is present at a binding interface with CEACAM5, and were identified as being important for high affinity binding, although conservative mutations can be made that retain high affinity binding. In other embodiments, wherein substitutions relative to the reference sequence are selected from allowable amino acids listed in Table 4. Allowable amino acid residues, as determined by SSM studies, are shown in the far right column of Table 4. In further embodiments, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or all 16 interface residues with CEACAM5 are conserved. Interface residues are denoted by “I” in the fourth column of Table 4. In other embodiments, relative to the reference sequence, at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or all 10 core residues are conserved. Core residues are denoted by “C” in the fourth column of Table 4. In one embodiment, relative to the reference sequence, one or more residues are substituted with a C or a K residue. As shown herein, substitution with C or K can facilitate conjugation of other moieties (such as cytotoxic therapeutics) to the polypeptide. In some embodiments, the one or more C or K residue can be substituted for a surface residue, as denoted by an “S” in column 4 of Table 4. In another embodiment, substitutions relative to the reference sequence are conservative amino acid substitutions. Table 4 In another embodiment, the polypeptide comprises an amino acid sequence at least 80%, 85%, 90%, 95%, 98%, or 100% identical to the amino acid of SEQ ID NO:60, wherein residues in parentheses are optional residues at the position, and X1, X2, X3, X4, and X5, may be any amino acid. The genus of SEQ ID NO:60 is based on a sequence alignment of the polypeptides of SEQ ID NO:11-14. See Figure 3. D(X1)K(D / Q / E)ELK(R / K)(A / S)FL(X2)AMVR(X3)(X4)VE(E / K)MEKILEELREL AEKHND(X5)ELRELYE(K / R)A(D / E)KA(F / L)EKFA (SEQ ID NO:60) In another embodiment, X1, X2, X3, X4, and X5 are defined as follow X1: L or R; X2: H, V, E, or D; X3: H or G; X4: D, R, or E; X5: H, D, or P. In a third aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:15-26, and wherein the polypeptide binds to Tumor- associated calcium signal transducer 2 (TROP2). The amino acid sequences of SEQ ID NO:15-26 are provided in Table 5. In one embodiment, the polypeptide comprises an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:15-26, wherein the polypeptide binds to TROP2. In another embodiment, the polypeptide comprises an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:15-26, wherein the polypeptide binds to TROP2. In a further embodiment, the polypeptide comprises an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:15-26, wherein the polypeptide binds to TROP2. In one embodiment, the polypeptide comprises an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:15-26, wherein the polypeptide binds to TROP2. Table 5 In one embodiment, relative to the reference sequence, residues noted as key residues are conserved (i.e., identical). Each of these “key” residues (identified by “K” in the annotation of “Key residues” for each design as listed in Table 5) is present at a binding interface with TROP2, and were identified as important but not necessarily required for high affinity binding. For example, in SEQ ID NO:15, residues 1, 7, 8, 11, 15, 17, 24, 26, and 30 are identified as “key” residues in the annotation shown in Table 5. Those of skill in the art will clearly understand what residues are the “key” residues in the other sequences shown in Table 5 based on the annotations provided. In another embodiment, substitutions relative to the reference sequence are conservative amino acid substitutions. As used herein with respect to all aspects and embodiments, conservative amino acid substitutions involve replacing a residue by a residue having similar physiochemical characteristics, e.g., substituting one aliphatic residue for another (such as Ile, Val, Leu, or Ala for one another), or substitution of one polar residue for another (such as between Lys and Arg; Glu and Asp; or Gln and Asn). Other such conservative substitutions, e.g., substitutions of entire regions having similar hydrophobicity characteristics, are known. Amino acids can be grouped according to similarities in the properties of their side chains (in A. L. Lehninger, in Biochemistry, second ed., pp.73-75, Worth Publishers, New York (1975)): (1) non-polar: Ala (A), Val (V), Leu (L), Ile (I), Pro (P), Phe (F), Trp (W), Met (M); (2) uncharged polar: Gly (G), Ser (S), Thr (T), Cys (C), Tyr (Y), Asn (N), Gln (Q); (3) acidic: Asp (D), Glu (E); (4) basic: Lys (K), Arg (R), His (H). Alternatively, naturally occurring residues can be divided into groups based on common side-chain properties: (1) hydrophobic: Met, Ala, Val, Leu, Ile; (2) neutral hydrophilic: Cys, Ser, Thr, Asn, Gln; (3) acidic: Asp, Glu; (4) basic: His, Lys, Arg; (5) residues that influence chain orientation: Gly, Pro; (6) aromatic: Trp, Tyr, Phe, His. In various embodiments, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues present at a binding interface with TROP2 are conserved. Interface residues are denoted by “I” in the annotation of “Interface residues” for each design as listed in Table 5. In other embodiments, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved. Residues present in helices are denoted by “H” in the annotation of “Secondary structure” for each design as listed in Table 5. In a further embodiment, relative to the reference sequence, one or more residues are substituted with a C or a K residue. As shown herein, substitution with C or K can facilitate conjugation of other moieties (such as cytotoxic therapeutics) to the polypeptide. In a fourth aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:27-29, and wherein the polypeptide binds to Tumor necrosis factor receptor superfamily member 17 (BCMA). The amino acid sequences of SEQ ID NO:27-29 are provided in Table 6. In one embodiment, the polypeptide comprises an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:27-29, wherein the polypeptide binds to BCMA. In another embodiment, the polypeptide comprises an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:27-29, wherein the polypeptide binds to BCMA. In a further embodiment, the polypeptide comprises an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:27-29, wherein the polypeptide binds to BCMA. In one embodiment, the polypeptide comprises an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:27-29, wherein the polypeptide binds to BCMA. Table 6 In some embodiments, relative to the reference sequence, residues noted as key residues are conserved (i.e., identical). Each of these “key” residues (identified by “K” in the annotation of “Key residues” for each design as listed in Table 6) is present at a binding interface with BCMA, and were identified as important but not necessarily required for high affinity binding. In other embodiments substitutions relative to the reference sequence are conservative amino acid substitutions. In further embodiments, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues present at a binding interface with BCMA are conserved. Interface residues are denoted by “I” in the annotation of “Interface residues” for each design as listed in Table 6. In some embodiments, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved. Residues present in helices are denoted by “H” in the annotation of “Secondary structure” for each design as listed in Table 6. In one embodiment, relative to the reference sequence, one or more residues are substituted with a C or a K residue. As shown herein, substitution with C or K can facilitate conjugation of other moieties (such as cytotoxic therapeutics) to the polypeptide. In a fifth aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:30-35, and wherein the polypeptide binds to Prolyl endopeptidase / Fibroblast Activation Protein (FAP). The amino acid sequences of SEQ ID NO:30-35 are provided in Table 7. In one embodiment, the polypeptide comprises an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:30-35, wherein the polypeptide binds to FAP. In another embodiment, the polypeptide comprises an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:30-35, wherein the polypeptide binds to FAP. In a further embodiment, the polypeptide comprises an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:30-35, wherein the polypeptide binds to FAP. In one embodiment, the polypeptide comprises an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:30-35, wherein the polypeptide binds to FAP. In another embodiment, the polypeptide comprises the amino acid sequence of SEQ ID NO:36-37. Table 7 In some embodiments, relative to the reference sequence, residues noted as key residues are conserved (i.e., identical); or wherein the polypeptide comprises the amino acid sequence of SEQ ID NO:36-37. Each of these “key” residues (identified by “K” in the annotation of “Key residues” for each design as listed in Table 7) is present at a binding interface with FAP, and were identified as important but not necessarily required for high affinity binding. SEQ ID NO:36 and 37 are consensus sequences of some of the sequences disclosed in Table 7. In other embodiments, substitutions relative to the reference sequence are conservative amino acid substitutions. In further embodiments, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues present at a binding interface with FAP are conserved. Interface residues present at a binding interface with FAP are denoted by “I” in the annotation of “Interface residues” for each design as listed in Table 7. In some embodiments, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved. Residues present in helices are denoted by “H” in the annotation of “Secondary structure” for each design as listed in Table 7. In one embodiment, relative to the reference sequence, one or more residues are substituted with a C or a K residue. As shown herein, substitution with C or K can facilitate conjugation of other moieties (such as cytotoxic therapeutics) to the polypeptide. In a sixth aspect, the disclosure provides polypeptides comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:38-54, and wherein the polypeptide binds to Inactive tyrosine-protein kinase transmembrane receptor ROR1 (ROR1). The amino acid sequences of SEQ ID NO:38-54 are provided in Table 8. In one embodiment, the polypeptide comprises an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:38-54, wherein the polypeptide binds to ROR1. In another embodiment, the polypeptide comprises an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:38-54, wherein the polypeptide binds to ROR1. In a further embodiment, the polypeptide comprises an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:38-54, wherein the polypeptide binds to ROR1. In one embodiment, the polypeptide comprises an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:38-54, wherein the polypeptide binds to ROR1. In another embodiment, the polypeptide comprises the amino acid sequence of SEQ ID NO:55-58. Table 8 In some embodiments, relative to the reference sequence, residues noted as key residues are conserved (i.e., identical); or wherein the polypeptide comprises the amino acid sequence of SEQ ID NO:55-58. Each of these “key” residues (identified by “K” in the annotation of “Key residues” for each design as listed in Table 8) is present at a binding interface with ROR1, and were identified as important but not necessarily required for high affinity binding. SEQ ID NO:55-58 are consensus sequences of some of the sequences disclosed in Table 8. In other embodiments, substitutions relative to the reference sequence are conservative amino acid substitutions. In further embodiments, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues present at a binding interface with ROR1 are conserved. Interface residues are denoted by “I” in the annotation of “Interface residues” for each design as listed in Table 8. In some embodiments, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved. Residues present in helices are denoted by “H” in the annotation of “Secondary structure” for each design as listed in Table 8. In one embodiment, relative to the reference sequence, one or more residues are substituted with a C or a K residue. As shown herein, substitution with C or K can facilitate conjugation of other moieties (such as cytotoxic therapeutics) to the polypeptide. The disclosure also provides fusion proteins of any aspect of the disclosure, comprising: (a) the polypeptide of any embodiment or combination of embodiments herein; and (b) one or more functional domains at the N-terminus and / or at the C-terminus of the polypeptide. In these embodiments, any functional domain may be fused to the polypeptides of the disclosure. In various non-limiting embodiments, the functional domain may comprise, for example, a targeting domain, a detectable domain, a scaffold domain, a secretion signal, an Fc domain, an oligomerization domain, a domain for half-life extension (e.g. albumin binding domain) or a therapeutic peptide domain (including but not limited to a therapeutic antibody or active fragment thereof). In one specific embodiment, the one or more functional domains comprises a domain for half-life extension (e.g. albumin binding domain). In another embodiment, the one or more functional domains may comprise one or more other polypeptide of the disclosure, to provide heterofunctional binders. For example, the fusion protein may comprise a fusion of a Her2 binder polypeptide of any embodiment or combination of embodiments of the first aspect of the disclosure, with a polypeptide of embodiment or combination of embodiments of the second aspect, or the third aspect, or the fourth, aspect, or the fifth aspect, or the sixth aspect of the disclosure, which may be used to target tumors with heterogeneous target expression or to enhance tumor specificity relative to healthy tissue. In another embodiment, the disclosure provides conjugates, comprising: (a) the polypeptide or fusion protein of any embodiment or combination of embodiments herein; and; and (b) an anti-tumor therapeutic covalently linked to the polypeptide or fusion protein. Any anti-tumor therapeutic may be used as appropriate for an intended purpose. In non-limiting embodiments, the anti-tumor therapeutic is selected from the group consisting of angiogenesis inhibitors, tubulin inhibitors, topoisomerase inhibitors, DNA damage inducers, immune checkpoint inhibitors, mTOR inhibitors, PI3K inhibitors, histone deacetylase inhibitors, and Hedgehog pathway blockers. In one embodiment, the anti-tumor therapeutic comprises an angiogenesis inhibitor selected from the group consisting of axitinib, bevacizumab, cabozantinib, everolimus, lenalidomide, lenvatinib mesylate, pazopanib, ramucirumab, regorafenib, sorafenib, sunitinib, thalidomide, vandetanib, and ziv-aflibercept. In various other embodiments, the anti-tumor therapeutic comprises: (a) a tubulin inhibitor is selected from the group consisting of monomethyl auristatin E (MMAE), mertansine (DM1), ravtansine (DM4), monomethyl auristatin F (MMAF), eribulin mesylate, maytansine, tubulysin, and duostatin; (b) a topoisomerase inhibitor selected from the group consisting of deruxtecan (DXD), exatecan mesylate, 7-Ethyl-10-hydroxycamptothecin (SN-38), and irinotecan (CPT- 11); (c) a DNA damage inducer selected from the group consisting of pyrrolobenzodiazepine (PBD), duocarmycin, PNU-159682, and DGN5; (d) an immune checkpoint inhibitor selected from the group consisting of pembrolizumab, nivolumab, and cemiplimab as anti-PD-1 antibodies, ipilimumab as an anti- CTLA-4 antibody, and atezolizumab, avelumab, and durvalumab as anti-PD-L1 antibodies); (e) a tyrosine kinase inhibitor selected from the group consisting of alectinib, brigatinib, ceritinib, crizotinib, entrectinib, lorlatinib, ALK, I, bosutinib, dasatinib, imatinib, nilotinib, ponatinib, afatinib, dacomitinib, erlotinib, gefitinib, lapatinib, neratinib, osimertinib, vandetanib, gilteritinib, midostaurin, erdafitinib, ruxolitinib, larotrectinib, axitinib, carbozantinib, lenvatinib, pazopanib, regorafenib, sorafenib, sunitinib, dabrafenib, encorafenib, vemurafenib, acalabrutinib, ibrutinib, binimetinib, cobimetinib, trametinib, abemaciclib, palbociclib, or ribociclib; (f) a proteasome inhibitor selected from the group consisting of ortezomib, carfizomib, ixazomib, delanzomib, oprozomib, and marizomib; (g) an mTOR inhibitor selected from the group consisting of everolimus, sirolimus, temsirolimus, everolimus, sirolimus, sirolimus protein-bound, and everolimus; (h) a PI3K inhibitor selected from the group consisting of copanlisib, alpelisib, idelalisib, duvelisib and umbralisib; (i) a histone deacetylase inhibitor selected from the group consisting of vorinostat, romidepsin, panobinostat, and belinostat; and / or (j) a Hedgehog pathway blocker selected from the group consisting of vismodegib, sonidegib, and glasdegib. In one specific embodiment, the anti-tumor therapeutic comprises monomethyl auristatin E (MMAE). As disclosed in the examples herein, the polypeptide binders bind their target with nanomolar or picomolar affinity or better. Thus, in various embodiments, the polypeptide, fusion protein, or conjugate of any embodiment herein binds its target with nanomolar or picomolar affinity or better. In another aspect the disclosure provides nucleic acids encoding the polypeptide or fusion protein of any embodiment or combination of embodiments of the disclosure. The nucleic acid sequence may comprise single stranded or double stranded RNA or DNA in genomic or cDNA form, or DNA-RNA hybrids, each of which may include chemically or biochemically modified, non-natural, or derivatized nucleotide bases. Such nucleic acid sequences may comprise additional sequences useful for promoting expression and / or purification of the encoded peptide or chimeric molecular construct, including but not limited to polyA sequences, modified Kozak sequences, and sequences encoding epitope tags, export signals, and secretory signals, nuclear localization signals, and plasma membrane localization signals. It will be apparent to those of skill in the art, based on the teachings herein, what nucleic acid sequences will encode the polypeptide or fusion protein of the disclosure. In a further aspect, the disclosure provides expression vectors comprising the nucleic acid of any aspect of the disclosure operatively linked to a suitable control sequence, such as a promoter. “Expression vector” includes vectors that operatively link a nucleic acid coding region or gene to any control sequences capable of effecting expression of the gene product. “Control sequences” operably linked to the nucleic acid sequences of the disclosure are nucleic acid sequences capable of effecting the expression of the nucleic acid molecules. The control sequences need not be contiguous with the nucleic acid sequences, so long as they function to direct the expression thereof. Thus, for example, intervening untranslated yet transcribed sequences can be present between a promoter sequence and the nucleic acid sequences and the promoter sequence can still be considered “operably linked” to the coding sequence. Other such control sequences include, but are not limited to, polyadenylation signals, termination signals, and ribosome binding sites. Such expression vectors can be of any type, including but not limited plasmid and viral-based expression vectors. The control sequence used to drive expression of the disclosed nucleic acid sequences in a mammalian system may be constitutive (driven by any of a variety of promoters, including but not limited to, CMV, SV40, RSV, actin, EF) or inducible (driven by any of a number of inducible promoters including, but not limited to, tetracycline, ecdysone, steroid-responsive). The expression vector must be replicable in the host organisms either as an episome or by integration into host chromosomal DNA. In various embodiments, the expression vector may comprise a plasmid, viral-based vector, or any other suitable expression vector. In another aspect, the disclosure provides host cells that comprise the polypeptide, fusion protein nucleic acid or expression vector (i.e.: episomal or chromosomally integrated) disclosed herein, wherein the host cells can be either prokaryotic or eukaryotic. The cells can be transiently or stably engineered to incorporate the expression vector of the disclosure, using techniques including but not limited to bacterial transformations, calcium phosphate co- precipitation, electroporation, or liposome mediated-, DEAE dextran mediated-, polycationic mediated-, or viral mediated transfection. The disclosure also provides pharmaceutical compositions, comprising: (a) the polypeptide, fusion protein, conjugate, nucleic acid, expression vector, and / or host cell of any embodiment or combination of embodiments herein; and (b) a pharmaceutically acceptable carrier. The compositions may further comprise (a) a lyoprotectant; (b) a surfactant; (c) a bulking agent; (d) a tonicity adjusting agent; (e) a stabilizer; (f) a preservative and / or (g) a buffer. In some embodiments, the buffer in the pharmaceutical composition is a Tris buffer, a histidine buffer, a phosphate buffer, a citrate buffer or an acetate buffer. The composition may also include a lyoprotectant, e.g. sucrose, sorbitol or trehalose. In certain embodiments, the composition includes a preservative e.g. benzalkonium chloride, benzethonium, chlorohexidine, phenol, m-cresol, benzyl alcohol, methylparaben, propylparaben, chlorobutanol, o-cresol, p-cresol, chlorocresol, phenylmercuric nitrate, thimerosal, benzoic acid, and various mixtures thereof. In other embodiments, the composition includes a bulking agent, like glycine. In yet other embodiments, the composition includes a surfactant e.g., polysorbate-20, polysorbate-40, polysorbate- 60, polysorbate-65, polysorbate-80 polysorbate- 85, poloxamer-188, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trilaurate, sorbitan tristearate, sorbitan trioleaste, or a combination thereof. The composition may also include a tonicity adjusting agent, e.g., a compound that renders the formulation substantially isotonic or isoosmotic with human blood. Exemplary tonicity adjusting agents include sucrose, sorbitol, glycine, methionine, mannitol, dextrose, inositol, sodium chloride, arginine and arginine hydrochloride. In other embodiments, the composition additionally includes a stabilizer, e.g., a molecule which substantially prevents or reduces chemical and / or physical instability of the nanostructure, in lyophilized or liquid form. Exemplary stabilizers include sucrose, sorbitol, glycine, inositol, sodium chloride, methionine, arginine, and arginine hydrochloride. The polypeptide, fusion protein, conjugate, nucleic acid, expression vector, and / or host cell may be the sole active agent in the composition, or the composition may further comprise one or more other agents suitable for an intended use. In a further aspect, the disclosure provides methods for treating a tumor, comprising administering to a subject in need thereof an amount effective to treat the tumor of the polypeptide, fusion protein, conjugate, nucleic acid, expression vector, host cell, and / or pharmaceutical composition of any embodiment or combination of embodiments herein. In another aspect, the disclosure provides methods for imaging a tumor, comprising administering to a subject in need thereof a detectable polypeptide, fusion protein, or conjugate of any embodiment or combination of embodiments herein under conditions suitable to bind a target of the polypeptide on the tumor, and detecting binding of the polypeptide, fusion protein, or conjugate to the tumor. As disclosed herein, the target specificity and unique target binding modes of the polypeptides disclosed herein makes them useful for treating tumors, targeted drug delivery, and diagnostic imaging. In some cases the target binding mode of the minibinders can induce receptor mediated endocytosis, thus further facilitating the potential for their use in treating tumors or as drug delivery vehicles. In one embodiment, the subject has a HER2-positive tumor, and the method comprises administering a polypeptide of any embodiment or combination of embodiments of the first aspect of the disclosure, or fusion proteins or conjugates thereof. In another embodiment, the subject has a CECAM-positive tumor, and the method comprises administering a polypeptide of any embodiment or combination of embodiments of the second aspect of the disclosure, or fusion proteins or conjugates thereof. In a further embodiment, the subject has a TROP2-positive tumor, and the method comprises administering a polypeptide of any embodiment or combination of embodiments of the third aspect of the disclosure, or fusion proteins or conjugates thereof. In one embodiment, the subject has a BCMA-positive tumor, and the method comprises administering a polypeptide of any embodiment or combination of embodiments of the fourth aspect of the disclosure, or fusion proteins or conjugates thereof. In another embodiment, the subject has a FAP-positive tumor, and the method comprises administering a polypeptide of any embodiment or combination of embodiments of the fifth aspect of the disclosure, or fusion proteins or conjugates thereof. In a further embodiment, the subject has a ROR1-positive tumor, and the method comprises administering a polypeptide of any embodiment or combination of embodiments of the sixth aspect of the disclosure, or fusion proteins or conjugates thereof. As used herein, "treat" or "treating" a disorder means accomplishing one or more of the following in a subject with the disorder: (a) reducing the severity of the disorder; (b) limiting development of symptoms characteristic of the disorder(s) being treated; (c) inhibiting worsening of symptoms characteristic of the disorder(s) being treated; (d) limiting recurrence of the disorder(s) in patients that have previously had the disorder(s); and (e) limiting recurrence of symptoms in patients that were previously symptomatic for the disorder(s). Detecting binding of the polypeptide, fusion protein, or conjugate to the tumor can be carried out via any suitable means. In some embodiments, the polypeptide, fusion protein, or conjugate comprises a detectable label, and detecting binding to the tumor comprises standard means for detecting the label used. The subject may be any subject that has a relevant disorder, or is or may be at risk of the relevant disorder. In one embodiment, the subject is a mammal, including but not limited to humans, dogs, cats, horses, cattle, etc. In one embodiment, the subject is a human. As used herein, an “effective” amount refers to an amount of the polypeptide, fusion protein, oligomer, nucleic acid, expression vector, and / or host cell that is effective for treating the disorder. The polypeptides, fusion proteins, oligomers, nucleic acids, expression vectors, and / or host cells are typically formulated as a pharmaceutical composition, such as those disclosed above, and can be administered via any suitable route, including but not limited to orally, by inhalation spray, ocularly, intravenously, subcutaneously, intraperitoneally, and intravesicularly in dosage unit formulations containing conventional pharmaceutically acceptable carriers, adjuvants, and vehicles. Any suitable dosage range may be used as determined by attending medical personnel. Dosage regimens can be adjusted to provide the optimum desired response. A suitable dosage range for the polypeptides or fusion proteins may, for instance, be 0.1 ug / kg- 100 mg / kg body weight; alternatively, it may be 0.5 ug / kg to 50 mg / kg; 1 ug / kg to 25 mg / kg, or 5 ug / kg to 10 mg / kg body weight. In some embodiments, the recommended dose could be lower than 0.1 mcg / kg, especially if administered locally (such as by intra-tumoral injection). In other embodiments, the recommended dose could be based on weight / m2 (i.e. body surface area), and / or it could be administered at a fixed dose (e.g., .05-100 mg). The polypeptides, fusion proteins, nucleic acids, expression vectors, and / or host cells can be delivered in a single bolus, or may be administered more than once (e.g., 2, 3, 4, 5, or more times) as determined by an attending physician. The polypeptides, fusion proteins, conjugates, nucleic acids, expression vectors, host cells, and / or pharmaceutical compositions made be administered as the sole therapeutic agent, or may be administered together with (i.e.: combined or separately) one or more other therapeutic agents as appropriate for an intended use. Examples We developed computer designed binding proteins called “minibinders” against multiple receptors overexpressed on cancer cells including Receptor tyrosine-protein kinase erbB-2 (HER2), Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), Tumor-associated calcium signal transducer 2 (TROP2), and Inactive tyrosine-protein kinase transmembrane receptor ROR1 (ROR1). Additionally, we developed slightly larger binders against Tumor necrosis factor receptor superfamily member 17 (BCMA). These receptors are highly expressed on various cancer cells and have no or low expression in most healthy tissues. Additionally we developed minibinders against Prolyl endopeptidase / Fibroblast Activation Protein (FAP), which is highly expressed on cancer associated fibroblasts that are common to all solid tumors, but not expressed on fibroblasts in healthy tissues. The target specificity and unique target binding modes of these minibinders make them useful for targeted drug delivery or diagnostic imaging. In some cases the target binding mode of the minibinders can induce receptor mediated endocytosis, thus further facilitating the potential for their use as drug delivery vehicles. Results De novo designed minibinders targeting Her2 are around 7 kDa and have low picomolar affinities as determined by octet BLI. Additionally SSMs of the binders displayed on yeast reveal the functional tolerance of all possible single point mutations, of which combinations of mutations can be selected to enhance function (binding affinity, binding specificity, stability, solubility, or cysteine conjugation). Exemplary results of such SSM studies are provided in Table 2 for Her2 binders, and Table 4 for CEACAM5 binders. Size- exclusion chromatography (SEC) shows the designs are well behaved monodisperse proteins, and cell binding assays show the designs can target human cells expressing the Her2 receptor, which can thus be used for diagnostic imaging of her2 positive cancers. The binders can be used for targeted delivery of cytotoxic drugs to cancer cells expressing her2 by conjugation of a cytotoxic drug to site specific cysteines engineered into the binders. Conjugation of the exemplary, potent cytotoxin MMAE to the binders is capable of killing cancer cells expressing Her2 with an LC50 of 600 pM in in vitro experiments while sparing non- expressing cells. See Figure 1. Cell viability of breast adenocarcinoma cell lines MCF7 (HER2-negative) and SKBR3 (HER2-positive) were assessed upon incubation with a HER2 minibinder (SEQ ID 6) conjugated to the potent cytotoxin Monomethyl auristatin E (MMAE) through a site-specific cysteine. The HER2 minibinder drug conjugate shows potent toxicity (LC50600 pM) against the HER2 expressing cell line, SKBR3 and no toxicity against the cell line lacking HER2 expression, MCF7. This demonstrates the high target selectivity of the minibinder that makes it suitable for use in targeted drug delivery or detection. Variants containing cysteine and / or defined number of lysines have been made for payload conjugation. Additionally, variants of the binding interface have been made that span almost three orders of magnitude affinity from 10 pM (her2_cb_0672; SEQ ID NO:2, as well as the designs of SEQ ID NO:3-7) to 200 pM (her2_cb_0672_15C_45H; SEQ ID NO:9) to 18 nM (her2_cb_0672_15C_33H; SEQ ID NO:8) to 80 nM (her2_cb_0672_15C_52H; SEQ ID NO:10). See Table 9. Table 9. Affinities of HER2 Targeting Binders A single parent binder was discovered that targets CEACAM5, and three 7 kDa binders with high sequence identity were developed by combo library optimization that bind with affinities of approximately 1 nM based on octet / BLI characterization. The combo library optimization involved mutating 10 positions on the parent binder with degenerate codons to include the most favorable binding mutations based on SSM and screening for higher affinity binders by yeast surface display. Additionally SSMs of the binders targeting CEACAM5 displayed on yeast reveal the functional tolerance of all possible single point mutations, of which combinations of mutations can be selected to enhance function (binding affinity, binding specificity, stability, solubility, or cysteine conjugation). SEC shows the designs are well-behaved monodisperse proteins. Seven 7-8 kDa binders were developed that bind TROP2 with affinities ranging from 300 pM to 20 nM based on octet / BLI characterization, and SEC shows the designs are well behaved monodisperse proteins. The binders consist of 3 and 4 helical bundles that span a range of binding modes and sequences. Three 30 kDa binders were developed that target BCMA with affinities of 100 pM, 100 pM, and 1 nM respectively based on octet / BLI characterization. SEC showed the designs are well behaved monodisperse proteins. Binders targeting two distinct regions of the FAP receptor were identified by yeast surface display. For FAP region 1 (defined as residue numbers 330-500 in uniprot entry Q12884), we identified three total binders (SEQ ID NO:30-32) belonging to two distinct clusters based on sequence identity and binding mode. These region 1 binders have estimated affinities on yeast display ranging from 1 to 30 nM. Additionally, for FAP region 2 (defined as residue numbers 150-370 in uniprot entry Q12884), we identified 3 total binders (SEQ ID NO:33-35) belonging to a single cluster based on sequence identity and binding mode. The region 2 binders have affinities ranging from 700 pM to 4 nM based on octet / BLI. Binders targeting two domains of the ROR1 receptor, based on an Alphafold2TMpredicted model were identified by yeast surface display. We defined domain 2 as residues 50-160 in uniprot entry Q01973, which Alphafold2Mpredicts as a beta sandwich. We identified 2 binders targeting domain 2 (SEQ ID NO:38-39). Based on sequence identity and binding mode, the binders belong to 2 distinct clusters. The binders to domain 2 bound on yeast surface display with estimated affinities in the range of 5 to 10 nM based on octet / BLI. Additionally, we defined domain 3 as residues 160-300 in uniprot entry Q01973, which Alphafold2TMpredicts as a helical bundle. We identified 15 total binders (SEQ ID NO:40-54) belonging to 7 distinct clusters based on sequence identity and binding mode. Four of the seven clusters contain 3 binders each, while the remaining 3 clusters contain a single binder each. These binders have affinities ranging from < 100 pM to 5 nM based on octet / BLI. Discussion Collectively, the designed minibinders and larger BCMA binders disclosed here that target multiple receptors overexpressed on tumor cells or on cancer associated fibroblasts represent promising tools for targeted drug delivery or diagnostic imaging as was demonstrated for the HER2 targeting binders in cell culture. Furthermore, bispecific binders made by combining two or more of these binders could have promising use in oncology to target tumors with heterogeneous target expression or to enhance tumor specificity relative to healthy tissue. Methods Octet / BLI analysis was done to determine binding affinities as follows. Biotinylated target protein was loaded onto streptavidin coated octet sensors to 0.6 - 0.7 response units from a 50 nM stock of target protein in octet buffer: 10 mM Hepes, 150 mM NaCl, 3 mM EDTA, 0.05% polysorbate 20, pH 7.4 + 1% Bovine Serum Albumin + 600 mM sucrose (600 mM sucrose is added to reduce nonspecific binding and is considered optional). A single sensor was left without target protein loaded to check as a control to check nonspecific binding to the sensor. Target loading took 100-200 seconds with shaking (1000 rpm). The target loaded sensors were then dipped in a well containing binder protein with 3 fold titration from 1000 nM to 4 nM in octet buffer + a 0 nM baseline reference and a 1000 nM control to check nonspecific binding to the sensor with the non-loaded sensor. The binder was left to associate to the target protein for 400 seconds with shaking (1000 rpm) and then the sensors were dipped in octet buffer to measure dissociation for 400 seconds with shaking (1000 rpm). The association and dissociation data was fitted with a 1 to 1 kinetic binding model (baseline subtracted and globally fit to the data from each titration) to determine binding affinity. SSM analysis was done by ordering a library of genes (oligo array) encoding every possible single point mutant of the parent binder and transforming this library into yeast for yeast surface display. The Library was sorted by Fluorescence-Activated Cell Sorting (FACS) at various concentrations of target protein (typically ranging from 1 uM to sub 1 nM). Subsequently, the sorted cells were analyzed by deep sequencing to determine the frequency of each mutation at each target concentration and this was used to estimate the binding affinity on yeast surface of the various mutations. SEC analysis was conducted by first growing a 50 mL culture expressing the protein of interest and purifying it by immobilized metal affinity chromatography (IMAC). Afterwards, purified protein was run over an S75 or S200 column on an AKTA Pure system to assess the purity and monodispersity of the protein of interest. Cell binding studies were conducted with purified minibinder containing a single surface cysteine residue that was conjugated to a fluorophore following manufactures protocols and purified by size exclusion chronography (SEC). Purified fluorescent minibinder was then mixed with cancer cells expressing or not expressing the target receptor and binding was assessed by flow cytometry and / or fluorescence microscopy. Cell viability was conducted by conjugating vcMMAE to the minibinder, purifying by SEC, and mixing at various concentration (typically from 10 pM to 100 nM) with cancer cells expressing the target of interest. After 72 hrs of incubation at 37°C, cell viability was assessed using commercially available ATP BioluminometricTMCell Viability Assay kit. Cell viability was plotted vs concentration to determine the LC50.

Claims

We claim:

1. A polypeptide comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:1-10, and wherein the polypeptide binds to Receptor tyrosine-protein kinase erbB-2 (HER2).

2. The polypeptide of claim 1, comprising an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:1-10, wherein the polypeptide binds to HER2.

3. The polypeptide of claim 1, comprising an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:1-10, wherein the polypeptide binds to HER2.

4. The polypeptide of claim 1, comprising an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:1-10, wherein the polypeptide binds to HER2.

5. The polypeptide of claim 1, comprising an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:1-10, wherein the polypeptide binds to HER2.

6. The polypeptide of any one of claims 1-5, wherein, relative to the reference sequence, residue 29 is L, residue 30 is A, residue 33 is Y, residue 46 is D, residue 55 is A, and residue 56 is R.

7. The polypeptide of any one of claims 1-6, wherein substitutions relative to the reference sequence are selected from allowable amino acids listed in Table 2.

8. The polypeptide of any one of claims 1-7, wherein, relative to the reference sequence, at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or all 19 interface residues are conserved.

9. The polypeptide of any one of claims 1-8, wherein, relative to the reference sequence, at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or all 14 core residues are conserved.

10. The polypeptide of any one of claims 1-9, wherein the polypeptide comprises an amino acid sequence at least 80%, 85%, 90%, 95%, 98%, or 100% identical to the amino acid sequence of SEQ ID NO:

59.

11. The polypeptide of claim 10, wherein X1, X2, X3, X4, X5, X6, X7, and X8 in SEQ ID NO:59 are defined as follows: X1: C or E; X2: V or Q; X3:Q, A, or E; X4: S, R, or K; X5: D, P, or A; X6: F, H, or I; X7: D, V, or G; X8: T, I, or K.

12. The polypeptide of any one of claims 1-11, comprising, relative to the reference sequence, one or more residues are substituted with a C or a K residue.

13. A polypeptide comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:11- 14, and wherein the polypeptide binds to carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5).

14. The polypeptide of claim 13, comprising an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:11- 14, wherein the polypeptide binds to CEACAM5.

15. The polypeptide of claim 13, comprising an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:11- 14, wherein the polypeptide binds to CEACAM5.

16. The polypeptide of claim 13, comprising an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:11- 14, wherein the polypeptide binds to CEACAM5.

17. The polypeptide of claim 13, comprising an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:11- 14, wherein the polypeptide binds to CEACAM5.

18. The polypeptide of any one of claims 13-17, wherein, relative to the reference sequence, residue 15 is V, residue 51 is A, and residue 55 is F.

19. The polypeptide of any one of claims 13-18, wherein substitutions relative to the reference sequence are selected from allowable amino acids listed in Table 4.

20. The polypeptide of any one of claims 13-19, wherein, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or all 16 interface residues are conserved.

21. The polypeptide of any one of claims 13-20, wherein, relative to the reference sequence, at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or all 10 core residues are conserved.

22. The polypeptide of any one of claims 13-21, wherein the polypeptide comprises an amino acid sequence at least 80%, 85%, 90%, 95%, 98%, or 100% identical to the amino acid sequence of SEQ ID NO:

60.

23. The polypeptide of claim 22, wherein X1, X2, X3, X4, and X5 in SEQ ID NO:59 are defined as follows: X1: L or R; X2: H, V, E, or D; X3: H or G; X4: D, R, or E; X5: H, D, or P.

24. The polypeptide of any one of claims 13-23, comprising, relative to the reference sequence, one or more residues are substituted with a C or a K residue.

25. A polypeptide comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:15- 26, and wherein the polypeptide binds to Tumor-associated calcium signal transducer 2 (TROP2).

26. The polypeptide of claim 25, comprising an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:15- 26, wherein the polypeptide binds to TROP2.

27. The polypeptide of claim25, comprising an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:15- 26, wherein the polypeptide binds to TROP2.

28. The polypeptide of claim 25, comprising an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:15- 26, wherein the polypeptide binds to TROP2. The polypeptide of claim 25, comprising an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:15- 26, wherein the polypeptide binds to TROP2.

30. The polypeptide of any one of claims 25-29, wherein, relative to the reference sequence, residues noted as key residues are conserved (i.e., identical).

31. The polypeptide of any one of claims 25-30, wherein substitutions relative to the reference sequence are conservative amino acid substitutions.

32. The polypeptide of any one of claims 25-31, wherein, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues are conserved.

33. The polypeptide of any one of claims 25-32, wherein, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved.

34. The polypeptide of any one of claims 25-33, comprising, relative to the reference sequence, one or more residues are substituted with a C or a K residue.

35. A polypeptide comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:27- 29, and wherein the polypeptide binds to Tumor necrosis factor receptor superfamily member 17 (BCMA).

36. The polypeptide of claim 35, comprising an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:27- 29, wherein the polypeptide binds to BCMA.

37. The polypeptide of claim 35, comprising an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:27- 29, wherein the polypeptide binds to BCMA.

38. The polypeptide of claim 35, comprising an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:27- 29, wherein the polypeptide binds to BCMA.

39. The polypeptide of claim 35, comprising an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:27- 29, wherein the polypeptide binds to BCMA.

40. The polypeptide of any one of claims 35-39, wherein, relative to the reference sequence, residues noted as key residues are conserved (i.e., identical).

41. The polypeptide of any one of claims 35-40, wherein substitutions relative to the reference sequence are conservative amino acid substitutions.

42. The polypeptide of any one of claims 35-41, wherein, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues are conserved.

43. The polypeptide of any one of claims 35-42, wherein, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved.

44. The polypeptide of any one of claims 35-43, comprising, relative to the reference sequence, one or more residues are substituted with a C or a K residue.

45. A polypeptide comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:30- 35, and wherein the polypeptide binds to Prolyl endopeptidase / Fibroblast Activation Protein (FAP) 46. The polypeptide of claim 45, comprising an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:30- 35, wherein the polypeptide binds to FAP.

47. The polypeptide of claim 45, comprising an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:30- 35, wherein the polypeptide binds to FAP.

48. The polypeptide of claim 45, comprising an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:30- 35, wherein the polypeptide binds to FAP.

49. The polypeptide of claim 45, comprising an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:30- 35, wherein the polypeptide binds to FAP.

50. The polypeptide of any one of claims 45-49, wherein, relative to the reference sequence, residues noted as key residues are conserved (i.e., identical); or wherein the polypeptide comprises the amino acid sequence of SEQ ID NO:36-37.

51. The polypeptide of any one of claims 45-50, wherein substitutions relative to the reference sequence are conservative amino acid substitutions.

52. The polypeptide of any one of claims 45-51, wherein, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues are conserved.

53. The polypeptide of any one of claims 45-52, wherein, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved.

54. The polypeptide of any one of claims 45-53, comprising, relative to the reference sequence, one or more residues are substituted with a C or a K residue.

55. A polypeptide comprising an amino acid sequence at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:38- 54, and wherein the polypeptide binds to Inactive tyrosine-protein kinase transmembrane receptor ROR1 (ROR1).

56. The polypeptide of claim 55, comprising an amino acid sequence at least 75% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:38- 54, wherein the polypeptide binds to ROR1.

57. The polypeptide of claim 55, comprising an amino acid sequence at least 85% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:38- 54, wherein the polypeptide binds to ROR1.

58. The polypeptide of claim 55, comprising an amino acid sequence at least 90% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:38- 54, wherein the polypeptide binds to ROR1.

59. The polypeptide of claim 55, comprising an amino acid sequence at least 95% identical to the amino acid sequence selected from the group consisting of SEQ ID NO:38- 54, wherein the polypeptide binds to ROR1.

60. The polypeptide of any one of claims 55-59, wherein, relative to the reference sequence, residues noted as key residues are conserved (i.e., identical); or wherein the polypeptide comprises the amino acid sequence of SEQ ID NO:55-58.

61. The polypeptide of any one of claims 55-60, wherein substitutions relative to the reference sequence are conservative amino acid substitutions.

62. The polypeptide of any one of claims 55-61, wherein, relative to the reference sequence, at least 12, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or more, or all interface residues are conserved.

63. The polypeptide of any one of claims 55-62, wherein, relative to the reference sequence, at least 70%, 75%, 80%, 85%, 90%, 95%, or 100% of residues present in helices are conserved.

64. The polypeptide of any one of claims 55-63, comprising, relative to the reference sequence, one or more residues are substituted with a C or a K residue.

65. A fusion protein, comprising: (a) the polypeptide of any one of claims 1-64; and (b) one or more functional domains at the N-terminus and / or at the C-terminus of the polypeptide.66 The fusion protein of claim 65, wherein the one or more functional domains comprises a domain for half-life extension, optionally wherein the domain for half-life extension comprises an albumin -domain.

67. The fusion protein of claim 65 or 66, wherein the polypeptide of any one of claims 1- 60 comprises a first polypeptide, and wherein the one or more functional domains comprises at least a second polypeptide of any one of claims 1-60 that bind to a different target, to provide a heterofunctional binder.

68. A conjugate, comprising: (a) the polypeptide or fusion protein of any one of claims 1-67; and (b) an anti-tumor therapeutic covalently linked to the polypeptide or fusion protein.

69. The conjugate of claim 68, wherein the anti-tumor therapeutic is selected from the group consisting of angiogenesis inhibitors, tubulin inhibitors, topoisomerase inhibitors, DNA damage inducers, immune checkpoint inhibitors, mTOR inhibitors, PI3K inhibitors, histone deacetylase inhibitors, and Hedgehog pathway blockers.

70. The conjugate of claim 69, wherein the angiogenesis inhibitor is selected from the group consisting of axitinib, bevacizumab, cabozantinib, everolimus, lenalidomide, lenvatinib mesylate, pazopanib, ramucirumab, regorafenib, sorafenib, sunitinib, thalidomide, vandetanib, and ziv-aflibercept; 71. The conjugate of any one of claims 68-70, wherein the anti-tumor therapeutic comprises monomethyl auristatin E (MMAE).

72. The polypeptide, fusion protein, or conjugate of any one of claims 1-71, wherein the polypeptide binds its target with nanomolar or picomolar affinity or better.

73. A nucleic acid encoding the polypeptide or fusion protein of any one of claims 1-67 or the conjugate of claim 68.

74. An expression vector comprising the nucleic acid of claim 73 operatively linked to a suitable control sequence, such as a promoter.

75. A host cell comprising the polypeptide, fusion protein, conjugate, nucleic acid, or expression vector of any one of claims 1-74.

76. A pharmaceutical composition, comprising: (a) the polypeptide, fusion protein, conjugate, nucleic acid, expression vector, and / or host cell of any one of claims 1-75; and (b) a pharmaceutically acceptable carrier.

77. A method for treating a tumor, comprising administering to a subject in need thereof an amount effective to treat of the polypeptide, fusion protein, conjugate, nucleic acid, expression vector, host cell, and / or pharmaceutical composition of any one of claims 1- 76 to treat the tumor.

78. A method for imaging a tumor, comprising administering to a subject in need thereof a detectable polypeptide, fusion protein, or conjugate of any one of claims 1-76 under conditions suitable to bind a target of the polypeptide on the tumor, and detecting binding of the polypeptide, fusion protein, or conjugate to the tumor.

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