WO2019135159A2 - Single-domain antibody-cytosine deaminase fusion proteins - Google Patents

Single-domain antibody-cytosine deaminase fusion proteins Download PDF

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Publication number
WO2019135159A2
WO2019135159A2 PCT/IB2019/000013 IB2019000013W WO2019135159A2 WO 2019135159 A2 WO2019135159 A2 WO 2019135159A2 IB 2019000013 W IB2019000013 W IB 2019000013W WO 2019135159 A2 WO2019135159 A2 WO 2019135159A2
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Prior art keywords
seq
fusion protein
functional variant
sdab
acid sequence
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PCT/IB2019/000013
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English (en)
French (fr)
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WO2019135159A3 (en
Inventor
Pei-Jiun Chen
Shu-Hua Lee
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Shanghai Lumosa Therapeutics Co Ltd
Lumosa Therapeutics Co Ltd
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Shanghai Lumosa Therapeutics Co Ltd
Lumosa Therapeutics Co Ltd
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Priority to KR1020207018591A priority Critical patent/KR20200106032A/ko
Priority to RU2020116541A priority patent/RU2020116541A/ru
Priority to JP2020532877A priority patent/JP2021511013A/ja
Priority to EP19736000.1A priority patent/EP3735420A4/en
Priority to MX2020006822A priority patent/MX2020006822A/es
Priority to AU2019205128A priority patent/AU2019205128A1/en
Priority to CN201980007078.7A priority patent/CN112272673A/zh
Priority to CA3087135A priority patent/CA3087135A1/en
Priority to BR112020013244-6A priority patent/BR112020013244A2/pt
Application filed by Shanghai Lumosa Therapeutics Co Ltd, Lumosa Therapeutics Co Ltd filed Critical Shanghai Lumosa Therapeutics Co Ltd
Publication of WO2019135159A2 publication Critical patent/WO2019135159A2/en
Publication of WO2019135159A3 publication Critical patent/WO2019135159A3/en
Priority to ZA2020/03893A priority patent/ZA202003893B/en
Priority to IL275691A priority patent/IL275691A/en
Anticipated expiration legal-status Critical
Priority to JP2023111309A priority patent/JP2023126935A/ja
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
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    • C07K16/00—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies
    • C07K16/18—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies against material from animals or humans
    • C07K16/32—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies against material from animals or humans against translation products of oncogenes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/50—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
    • A61K47/51—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent
    • A61K47/68—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates the non-active ingredient being a modifying agent the modifying agent being an antibody, an immunoglobulin or a fragment thereof, e.g. an Fc-fragment
    • A61K47/6891—Pre-targeting systems involving an antibody for targeting specific cells
    • A61K47/6899—Antibody-Directed Enzyme Prodrug Therapy [ADEPT]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
    • C07K14/705—Receptors; Cell surface antigens; Cell surface determinants
    • C07K14/70503—Immunoglobulin superfamily
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    • C07K16/00—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies
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    • C07K16/28—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
    • C07K16/2863—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against receptors for growth factors, growth regulators
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    • C07K16/28—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
    • C07K16/2887—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against CD20
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
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    • C07K16/00—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies
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    • C07K16/28—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
    • C07K16/30—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants from tumour cells
    • C07K16/3007—Carcino-embryonic Antigens
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    • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
    • C12N9/14—Hydrolases (3)
    • C12N9/78—Hydrolases (3) acting on carbon to nitrogen bonds other than peptide bonds (3.5)
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    • C12Y—ENZYMES
    • C12Y305/00—Hydrolases acting on carbon-nitrogen bonds, other than peptide bonds (3.5)
    • C12Y305/04—Hydrolases acting on carbon-nitrogen bonds, other than peptide bonds (3.5) in cyclic amidines (3.5.4)
    • C12Y305/04001—Cytosine deaminase (3.5.4.1)
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K39/00—Medicinal preparations containing antigens or antibodies
    • A61K2039/505—Medicinal preparations containing antigens or antibodies comprising antibodies
    • A—HUMAN NECESSITIES
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    • C07K2317/20—Immunoglobulins specific features characterized by taxonomic origin
    • C07K2317/24—Immunoglobulins specific features characterized by taxonomic origin containing regions, domains or residues from different species, e.g. chimeric, humanized or veneered
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    • C07K2317/56—Immunoglobulins specific features characterized by immunoglobulin fragments variable (Fv) region, i.e. VH and/or VL
    • C07K2317/565—Complementarity determining region [CDR]
    • C—CHEMISTRY; METALLURGY
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    • C07K2317/50—Immunoglobulins specific features characterized by immunoglobulin fragments
    • C07K2317/56—Immunoglobulins specific features characterized by immunoglobulin fragments variable (Fv) region, i.e. VH and/or VL
    • C07K2317/569—Single domain, e.g. dAb, sdAb, VHH, VNAR or nanobody®
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/70—Immunoglobulins specific features characterized by effect upon binding to a cell or to an antigen
    • C07K2317/73—Inducing cell death, e.g. apoptosis, necrosis or inhibition of cell proliferation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/70—Immunoglobulins specific features characterized by effect upon binding to a cell or to an antigen
    • C07K2317/76—Antagonist effect on antigen, e.g. neutralization or inhibition of binding
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/90—Immunoglobulins specific features characterized by (pharmaco)kinetic aspects or by stability of the immunoglobulin
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/90—Immunoglobulins specific features characterized by (pharmaco)kinetic aspects or by stability of the immunoglobulin
    • C07K2317/92—Affinity (KD), association rate (Ka), dissociation rate (Kd) or EC50 value
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide
    • C07K2319/20—Fusion polypeptide containing a tag with affinity for a non-protein ligand
    • C07K2319/21—Fusion polypeptide containing a tag with affinity for a non-protein ligand containing a His-tag
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide
    • C07K2319/30—Non-immunoglobulin-derived peptide or protein having an immunoglobulin constant or Fc region, or a fragment thereof, attached thereto
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide
    • C07K2319/33—Fusion polypeptide fusions for targeting to specific cell types, e.g. tissue specific targeting, targeting of a bacterial subspecies
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide
    • C07K2319/70—Fusion polypeptide containing domain for protein-protein interaction

Definitions

  • the disclosure relates to fusion proteins, methods of making fusion proteins, and methods of using fusion proteins. More specifically, the disclosure relates to fusion proteins comprising a functional single-domain antibody (sdAb)
  • a VHH or a nanobody e.g., a VHH or a nanobody
  • a functional variant thereof against a cellular protein and a cytosine deaminase (CD) protein, or a functional variant thereof, optionally connected via a peptide linker.
  • the sdAb or functional variant thereof may be connected to the N-terminus or to the C-terminus of the CD protein or functional variant thereof, optionally via a peptide linker.
  • the fusion proteins of the disclosure also have CD activity.
  • the disclosure also relates to pharmaceutical compositions or formulations comprising such fusion proteins and pharmaceutically acceptable excipients, as well as medical uses of these fusion proteins.
  • the chemotherapeutic drug 5-fluorouracil (5-FU) has been widely used in cancer treatment, but systemic therapy with 5-FU is associated with severe toxic side effects. This agent inhibits cell growth by interfering with transcription and can be useful in the treatment of cancer and other proliferative diseases.
  • Cytosine deaminase (CD) converts the non- toxic prodrug 5-fluorocytosine (5-FC) to the cytotoxic agent 5-fluorouracil.
  • 5-FC is not toxic to human cells because of the lack of CD in human cells.
  • the cytosine deaminase gene, co-administered with the 5- fluorocytosine prodrug, is one of the most widely tested suicide systems in cancer gene therapy.
  • ADPT Antibody-directed enzyme-prodrug therapy
  • Deckert et al. disclosed an A33scFv-cytosine deaminase recombinant protein and demonstrated specific antigen binding and enzyme activity thereof.
  • A33scFv-CD was expressed by a T7-RNA polymerase-controlled bacterial system using BL21 Escherichia coli /.DE3 lysogens. Fusion proteins were expressed as inclusion bodies with a final culture yield of about 100 pg/L (British Journal of Cancer (2003) 88, 937-939).
  • CD fusion proteins that have promising production yield for industrial use and that demonstrate specific antigen binding and enzyme activity.
  • This disclosure provides fusion proteins, methods of making fusion proteins, and methods of using fusion proteins.
  • the following are non- limiting exemplary embodiments of the disclosure.
  • the fusion protein comprises formula I or formula II:
  • N is a single-domain antibody (sdAb) or a functional variant thereof
  • C is a cytosine deaminase (CD) protein or a functional variant thereof.
  • the fusion protein comprises formula I and the C-terminus of a peptide linker or the C-terminus of a sdAb or functional variant thereof is fused to the N-terminus of a CD protein or functional variant thereof.
  • a peptide linker is not present and the C-terminus of a sdAb or functional variant thereof is fused to the N-terminus of a CD protein or functional variant thereof.
  • At least one peptide linker is present and the C-terminus of a sdAb or functional variant thereof is fused to the N- terminus of a peptide linker, and the C-terminus of a peptide linker is fused to the N- terminus of another peptide linker or to the N-terminus of a CD protein or functional variant thereof.
  • the fusion protein comprises formula II and the C-terminus of a peptide linker or the C-terminus of a CD protein or functional variant thereof is fused to the N-terminus of a sdAb or functional variant thereof.
  • a peptide linker is not present and the C- terminus of a CD protein or functional variant thereof is fused to the N-terminus of a sdAb or functional variant thereof.
  • At least one peptide linker is present and the C-terminus of a CD protein or functional variant thereof is fused to the N-terminus of a peptide linker, and the C-terminus of a peptide linker is fused to the N-terminus of another peptide linker or to the N-terminus of a sdAb or functional variant thereof.
  • the fusion protein consists essentially of formula I. In some embodiments, the fusion protein is formula I. [0015] In some embodiments, the fusion protein consists essentially of formula II. In some embodiments, the fusion protein is formula II.
  • the sdAb or functional variant thereof binds to a target, wherein the target is selected from the group consisting of a cell membrane molecule, a secreted molecule, and an intracellular molecule.
  • the target is a tumor-associated antigen or a tumor-specific antigen.
  • the target is selected from the group consisting of EGFR, 5T4, A33, AFP, Beta-catenin, BRCA1, BRCA2, C242, CCR4, CD152, CD19, CD20, CD200, CD22, CD221, CD23, CD30, CD3, CD37, CD40, CD44, CD5, CD51, CD52, CD56, CD64, CD74, CD80, CDCP1, c-KIT, COX-2, cMET, CSF1R, CTEA-4, EGF2, ErbB2, ErbB3, FGFR1, FGFR2, FGFR3, FET3, HER2, HER3, HIF- Ia, HEA-DR, IGF-IR, mTOR, NPC-1C, P53, PDGFRa, PDGFR , PLGF, PSA, RGMa, RoN, TNF, TP53, TPD52, VEGFR1, VEGFR2, VEGFR3, CA-IX, anb3, a5b1, FAP
  • the target is selected from the group consisting of EGFR, c-KIT, cMET, HER2, HER3, FGFR1, FGFR2, FGFR3, IGF-IR, P53, PDGFRa, VEGFR1, VEGFR2, VEGFR3, CA-IX, anb3, a5b1, MUC16, carcinoembryonic antigen (CEA), prostate-specific membrane antigen, Cancer-testis (CT) antigens (e.g., NY-ESO-l, MAGE- A3, MAGE-A1), Mesothelin, EpCAM, integrin a6b4, CEACAM6, integrin a3b1, integrin anb3, PD-L1, AXL, CDH6, DLL3, EDNRB, EFNA4, NEPP3, EPHA2, FOLR1, LewisY, GPNMB, GUCY2C, HAVCR1, Integrin a, LYPD3, MUC1, NECTIN4, NOTCH3, PTK7, S
  • the target is VEGFR2, EGER, CEA, HER2, or
  • the target is VEGFR2. In some embodiments, the target is EGFR.
  • the sdAb or functional variant thereof comprises a complementarity determining region 1 (CDR1) selected from the group consisting of SEQ ID NOs: 28, 31, and 34; a CDR2 selected from the group consisting of SEQ ID NOs: 29, 32, and 35; and a CDR3 selected from the group consisting of SEQ ID NOs: 30, 33, and 36.
  • CDR1 complementarity determining region 1
  • the sdAb or functional variant thereof consists essentially of a CDR1 selected from the group consisting of SEQ ID NOs: 28, 31, and 34; a CDR2 selected from the group consisting of SEQ ID NOs: 29, 32, and 35; and a CDR3 selected from the group consisting of SEQ ID NOs: 30, 33, and 36.
  • the sdAb or functional variant thereof consists of a CDR1 selected from the group consisting of SEQ ID NOs: 28, 31, and 34; a CDR2 selected from the group consisting of SEQ ID NOs: 29, 32, and 35; and a CDR3 selected from the group consisting of SEQ ID NOs: 30, 33, and 36.
  • the sdAb or functional variant thereof comprises the amino acid sequence of SEQ ID NO: 23 (3VGR19). In some aspects, the sdAb or functional variant thereof consists essentially of the amino acid sequence of SEQ ID NO: 23 (3VGR19). In some aspects, the sdAb or functional variant thereof consists of the amino acid sequence of SEQ ID NO: 23 (3VGR19).
  • the sdAb or functional variant thereof comprises the amino acid sequence of SEQ ID NO: 24 (4VGR17). In some aspects, the sdAb or functional variant thereof consists essentially of the amino acid sequence of SEQ ID NO: 24 (4VGR17). In some aspects, the sdAb or functional variant thereof consists of the amino acid sequence of SEQ ID NO: 24 (4VGR17). In some embodiments, the sdAb or functional variant thereof comprises the amino acid sequence of SEQ ID NO: 25 (4VGR38). In some aspects, the sdAb or functional variant thereof consists essentially of the amino acid sequence of SEQ ID NO: 25 (4VGR38). In some aspects, the sdAb or functional variant thereof consists of the amino acid sequence of SEQ ID NO: 25 (4VGR38).
  • the sdAb or functional variant thereof comprises a CDR1 selected from the group consisting of SEQ ID NOs: 37 and 40, a CDR2 selected from the group consisting of SEQ ID NOs: 38 and 41, and a CDR3 selected from the group consisting of SEQ ID NOs: 39 and 42.
  • the sdAb or functional variant thereof consists essentially of a CDR1 selected from the group consisting of SEQ ID NOs: 37 and 40, a CDR2 selected from the group consisting of SEQ ID NOs: 38 and 41, and a CDR3 selected from the group consisting of SEQ ID NOs: 39 and 42.
  • the sdAb or functional variant thereof consists of a CDR1 selected from the group consisting of SEQ ID NOs: 37 and 40, a CDR2 selected from the group consisting of SEQ ID NOs: 38 and 41, and a CDR3 selected from the group consisting of SEQ ID NOs: 39 and 42.
  • the sdAb or functional variant thereof comprises the amino acid sequence of SEQ ID NO: 26 (VHH122).
  • the sdAb or functional variant thereof consists essentially of the amino acid sequence of SEQ ID NO: 26 (VHH122).
  • the sdAb or functional variant thereof consists of the amino acid sequence of SEQ ID NO: 26 (VHH122).
  • the sdAb or functional variant thereof comprises the amino acid sequence of SEQ ID NO: 27 (7D12). In some aspects, the sdAb or functional variant thereof consists essentially of the amino acid sequence of SEQ ID NO: 27 (7D12). In some aspects, the sdAb or functional variant thereof consists of the amino acid sequence of SEQ ID NO: 27 (7D12).
  • the sdAb or functional variant thereof comprises a CDR1 selected from the group consisting of SEQ ID NOs: 199, 202, and 205; a CDR2 selected from the group consisting of SEQ ID NOs: 200, 203, and 206; and a CDR3 selected from the group consisting of SEQ ID NOs: 201, 204, and 207.
  • the sdAb or functional variant thereof consists essentially of a CDR1 selected from the group consisting of SEQ ID NOs: 199, 202, and 205; a
  • CDR2 selected from the group consisting of SEQ ID NOs: 200, 203, and 206; and a
  • the sdAb or functional variant thereof consists of a CDR1 selected from the group consisting of SEQ ID NOs: 199, 202, and 205; a CDR2 selected from the group consisting of SEQ ID NOs: 200, 203, and 206; and a CDR3 selected from the group consisting of SEQ ID NOs: 201, 204, and 207.
  • the sdAb or functional variant thereof comprises the amino acid sequence of SEQ ID NO: 69 (2D3). In some aspects, the sdAb or functional variant thereof consists essentially of the amino acid sequence of SEQ ID NO: 69 (2D3). In some aspects, the sdAb or functional variant thereof consists of the amino acid sequence of SEQ ID NO: 69 (2D3). In some embodiments, the sdAb or functional variant thereof comprises the amino acid sequence of SEQ ID NO: 70 (5F7). In some aspects, the sdAb or functional variant thereof consists essentially of the amino acid sequence of SEQ ID NO: 70 (5F7).
  • the sdAb or functional variant thereof consists of the amino acid sequence of SEQ ID NO: 70 (5F7). In some embodiments, the sdAb or functional variant thereof comprises the amino acid sequence of SEQ ID NO: 71 (47D5). In some aspects, the sdAb or functional variant thereof consists essentially of the amino acid sequence of SEQ ID NO: 71 (47D5). In some aspects, the sdAb or functional variant thereof consists of the amino acid sequence of SEQ ID NO: 71 (47D5).
  • the sdAb or functional variant thereof comprises a CDR1 of SEQ ID NO: 208, a CDR2 of SEQ ID NO: 209, and a CDR3 of SEQ ID NO: 210.
  • the sdAb or functional variant thereof consists essentially of a CDR1 of SEQ ID NO: 208, a CDR2 of SEQ ID NO: 209, and a CDR3 of SEQ ID NO: 210.
  • the sdAb or functional variant thereof consists of a CDR1 of SEQ ID NO: 208, a CDR2 of SEQ ID NO: 209, and a CDR3 of SEQ ID NO: 210.
  • the sdAb or functional variant thereof comprises the amino acid sequence of SEQ ID NO: 75 (BCD090-M2). In some aspects, the sdAb or functional variant thereof consists essentially of the amino acid sequence of SEQ ID NO: 75 (BCD090-M2). In some aspects, the sdAb or lunctional variant thereof consists of the amino acid sequence of SEQ ID NO: 75 (BCD090-M2).
  • the sdAb or functional variant thereof comprises a CDR1 selected from the group consisting of SEQ ID NOs: 211 and 214, a CDR2 selected from the group consisting of SEQ ID NOs: 212 and 215, and a CDR3 selected from the group consisting of SEQ ID NOs: 213 and 216.
  • a CDR1 selected from the group consisting of SEQ ID NOs: 211 and 214
  • a CDR2 selected from the group consisting of SEQ ID NOs: 212 and 215
  • a CDR3 selected from the group consisting of SEQ ID NOs: 213 and 216.
  • the sdAb or functional variant thereof consists essentially of a CDR1 selected from the group consisting of SEQ ID NOs: 211 and 214, a CDR2 selected from the group consisting of SEQ ID NOs: 212 and 215, and a CDR3 selected from the group consisting of SEQ ID NOs: 213 and 216.
  • the sdAb or functional variant thereof consists of a CDR1 selected from the group consisting of SEQ ID NOs: 211 and 214, a CDR2 selected from the group consisting of SEQ ID NOs: 212 and 215, and a CDR3 selected from the group consisting of SEQ ID NOs: 213 and 216.
  • the sdAb or functional variant thereof comprises the amino acid sequence of SEQ ID NO: 77 (ABS29544.1). In some aspects, the sdAb or functional variant thereof consists essentially of the amino acid sequence of SEQ ID NO: 77 (ABS29544.1). In some aspects, the sdAb or functional variant thereof consists of the amino acid sequence of SEQ ID NO: 77 (ABS29544.1). In some embodiments, the sdAb or functional variant thereof comprises the amino acid sequence of SEQ ID NO: 79 (NbCEA5). In some aspects, the sdAb or functional variant thereof consists essentially of the amino acid sequence of SEQ ID NO: 79 (NbCEA5). In some aspects, the sdAb or functional variant thereof consists of the amino acid sequence of SEQ ID NO: 79 (NbCEA5).
  • At least one peptide linker is present and comprises the amino acid sequence (GGGGS)n (SEQ ID NO: 1), wherein n is 1, 2, 3, 4, 5, or 6. In some embodiments, at least one peptide linker is present and comprises the amino acid sequence of SEQ ID NO: 4 or SEQ ID NO: 5. In some embodiments, at least one peptide linker is present and comprises the amino acid sequence
  • the CD protein or functional variant thereof is a bacterial CD protein or a functional variant thereof or a yeast CD protein or a functional variant thereof.
  • the CD protein or functional variant thereof comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 21, 22, 186, and 187. In some aspects, the CD protein or functional variant thereof consists essentially of an amino acid sequence selected from the group consisting of SEQ ID NOs: 21, 22, 186, and 187. In some aspects, the CD protein or functional variant thereof consists of an amino acid sequence selected from the group consisting of SEQ ID NOs: 21, 22, 186, and 187. In some aspects, the CD comprises, consists essentially of, or consists of the amino acid sequence of SEQ ID NO: 22. In some aspects, the CD comprises, consists essentially of, or consists of the amino acid sequence of SEQ ID NO: 187.
  • the CD protein or functional variant thereof comprises an amino acid sequence that is at least 90% identical, at least 91% identical, at least 92% identical, at least 93% identical, at least 94% identical, at least 95% identical, at least 96% identical, at least 97% identical, at least 98% identical, at least 99% identical, or 100% identical to any one of SEQ ID NOs: 21, 22, 186, or 187.
  • the fusion protein comprises a functional variant of a CD protein having the starting amino acid sequence of SEQ ID NO: 21 or 22, wherein the functional variant comprises at least one mutation compared to the starting sequence selected from the group consisting of Y84A, Y84H, T85D, T86E,
  • the fusion protein comprises a functional variant of a CD protein having the starting amino acid sequence of SEQ ID NO: 186 or 187, wherein the functional variant comprises at least one mutation compared to the starting sequence selected from the group consisting of Y85A, Y85H, T86D, T87E, M93N, M93A, M93K, M93Q, V129A, V129T, V130A, V130L, V130I,
  • V130T, V131A, and V131T are V130T, V131A, and V131T.
  • the functional variant of CD comprises an amino acid sequence selected from SEQ ID NOs: 22, 187, 189, 190, 191, 192, 193, and 194. In some embodiments, the functional variant of CD consists essentially of an amino acid sequence selected from SEQ ID NOs: 22, 187, 189, 190, 191, 192, 193, and 194. In some embodiments, the functional variant of CD consists of an amino acid sequence selected from SEQ ID NOs: 22, 187, 189, 190, 191, 192, 193, and 194.
  • the fusion protein comprises an anti-VEGFR2 sdAb or functional variant thereof and a CD protein or functional variant thereof.
  • the fusion protein comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 7, SEQ ID NO: 7 without a HIS -tag (i.e., amino acids 1-297 of SEQ ID NO: 7), SEQ ID NO: 9, SEQ ID NO: 9 without a HIS-tag (i.e., amino acids 1-297 of SEQ ID NO: 9), SEQ ID NO: 11, and SEQ ID NO: 11 without a HIS-tag (i.e., amino acids 1-297 of SEQ ID NO: 11).
  • the fusion protein comprises an anti-EGFR sdAb or functional variant thereof and a CD protein or functional variant thereof.
  • the fusion protein comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 13, SEQ ID NO: 13 without a HIS-tag (i.e., amino acids 1-297 of SEQ ID NO: 13), SEQ ID NO: 15, SEQ ID NO: 15 without a HIS-tag (i.e., amino acids 1-297 of SEQ ID NO: 15), SEQ ID NO: 17, and SEQ ID NO: 17 without a HIS-tag (i.e., amino acids 1-297 of SEQ ID NO: 17, i.e. SEQ ID NO: 19).
  • the fusion protein comprises an anti-HER2 sdAb or functional variant thereof and a CD protein or functional variant thereof.
  • the fusion protein comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 72, SEQ ID NO: 72 without a HIS-tag (i.e., amino acids 1-297 of SEQ ID NO: 72), SEQ ID NO: 73, SEQ ID NO: 73 without a HIS-tag (i.e., amino acids 1-291 of SEQ ID NO: 73), SEQ ID NO: 74, and SEQ ID NO: 74 without a HIS-tag (i.e., amino acids 1-292 of SEQ ID NO: 74).
  • the fusion protein comprises an anti-HER3 sdAb or functional variant thereof and a CD protein or functional variant thereof.
  • the fusion protein comprises an amino acid sequence of SEQ ID NO: 76 and SEQ ID NO: 76 without a HIS-tag (i.e., amino acids 1-300 of SEQ ID NO: 76).
  • the fusion protein comprises an anti-CEA sdAb or functional variant thereof and a CD protein or functional variant thereof.
  • the fusion protein comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 78, SEQ ID NO: 78 without a HIS-tag (i.e., amino acids 1-293 of SEQ ID NO: 78), SEQ ID NO: 80, and SEQ ID NO: 80 without a HIS-tag (i.e., amino acids 1-296 of SEQ ID NO: 80).
  • the fusion protein comprises a de- immunized sdAb (e.g., a functional variant of sdAb having one or more de-immunizing mutations) and/or a de-immunized CD (e.g., a functional variant of CD having one or more de-immunizing mutations).
  • a de- immunized sdAb e.g., a functional variant of sdAb having one or more de-immunizing mutations
  • a de-immunized CD e.g., a functional variant of CD having one or more de-immunizing mutations
  • the fusion protein comprises at least one de-immunizing mutation in at least one T cell epitope selected from the group consisting of Epitope 1 (SEQ ID NO: 63), Epitope 2 (SEQ ID NO: 64), Epitope 3 (SEQ ID NO: 65), Epitope 4 (SEQ ID NO: 66), Epitope 5 (SEQ ID NO: 67), and Epitope 6 (SEQ ID NO: 68).
  • the fusion protein comprises an amino acid sequence selected from SEQ ID NOs: 93-185.
  • the fusion protein consists essentially of an amino acid sequence selected from SEQ ID NOs: 93-185.
  • the fusion protein consists of an amino acid sequence selected from SEQ ID NOs: 93-185.
  • the fusion protein comprises amino acids 1-297 of an amino acid sequence selected from the group consisting of SEQ ID NOs: 93- 181. In some embodiments, the fusion protein consists essentially of amino acids 1- 297 of an amino acid sequence selected from the group consisting of SEQ ID NOs: 93-181. In some embodiments, the fusion protein consists of amino acids 1-297 of an amino acid sequence selected from the group consisting of SEQ ID NOs: 93-181.
  • the fusion protein consists essentially of an amino acid sequence selected from SEQ ID NOs: 182-185.
  • the fusion protein comprises the amino acid sequence of SEQ ID NO: 19. In some embodiments, the fusion protein consists essentially of the amino acid sequence of SEQ ID NO: 19. In some embodiments, the fusion protein consists of the amino acid sequence of SEQ ID NO: 19.
  • the fusion protein consists essentially of an amino acid sequence selected from SEQ ID NOs: 19, 182, 183, 184, and 185.
  • the disclosure relates to a pharmaceutical composition or pharmaceutical formulation comprising at least one fusion protein of the disclosure.
  • the pharmaceutical composition or pharmaceutical formulation comprises at least one fusion protein of the disclosure and at least one
  • the disclosure relates to a method of treating cancer in a subject in need thereof, the method comprising administering to the subject and effective amount of at least one fusion protein or pharmaceutical composition of the disclosure.
  • the at least one fusion protein or the pharmaceutical composition is administered parenterally.
  • the method of treating cancer in a subject in need thereof further comprises administering to the subject an effective amount of a substrate for cytosine deaminase.
  • the substrate comprises a prodrug of 5-fluorouracil.
  • the prodrug of 5-fluorouracil is selected from the group consisting of 5-fluorocytosine (5-FC), Toca FC, analogs of 5- FC, and photoactivatable compounds, salts or esters thereof.
  • the prodrug administered to the subject is 5-FC.
  • the cancer is selected from the group consisting of colon cancer, stomach cancer, pancreatic cancer, breast cancer, basal cell carcinoma, Bowen’s disease, cervical cancer, ocular surface squamous neoplasia, melanoma, renal cell carcinoma, lung cancer, bladder cancer, gall bladder cancer, laryngeal cancer, liver cancer, thyroid cancer, salivary gland cancer, prostate cancer, colorectal cancer, head and neck cancer, cholangiocarcinoma, esophagus cancer, bone cancer, endometrial cancer, ovarian cancer, soft tissue sarcoma, and Merkel cell carcinoma.
  • the cancer is a solid tumor.
  • the solid tumor is colon cancer, colorectal cancer, pancreatic cancer, or head and neck cancer.
  • the disclosure relates to a nucleic acid molecule comprising a nucleic acid sequence encoding a fusion protein of any one of the preceding embodiments.
  • the disclosure relates to a nucleic acid molecule comprising a codon-optimized nucleic acid sequence encoding a sdAb or functional variant thereof of any fusion protein of any one of the preceding embodiments. In some aspects, the disclosure relates to a nucleic acid molecule comprising a codon- optimized nucleic acid sequence encoding a CD or functional variant thereof of any fusion protein of any one of the preceding embodiments.
  • the nucleic acid molecule comprises the nucleic acid sequence of SEQ ID NO: 8. In some embodiments, the nucleic acid molecule comprises the nucleic acid sequence of SEQ ID NO: 10. In some embodiments, the nucleic acid molecule comprises the nucleic acid sequence of SEQ ID NO: 12. In some embodiments, the nucleic acid molecule comprises the nucleic acid sequence of SEQ ID NO: 14. In some embodiments, the nucleic acid molecule comprises the nucleic acid sequence of SEQ ID NO: 16. In some embodiments, the nucleic acid molecule comprises the nucleic acid sequence of SEQ ID NO: 18. In some embodiments, the nucleic acid molecule comprises the nucleic acid sequence of SEQ ID NO: 20.
  • the nucleic acid molecule comprises the nucleic acid sequence of SEQ ID NO: 195. In some embodiments, the nucleic acid molecule comprises the nucleic acid sequence of SEQ ID NO: 196. In some embodiments, the nucleic acid molecule comprises the nucleic acid sequence of SEQ ID NO: 197. In some embodiments, the nucleic acid molecule comprises the nucleic acid sequence of
  • the disclosure relates to a vector comprising a nucleic acid encoding a fusion protein of any of the preceding embodiments.
  • the disclosure relates to a host cell comprising a vector or nucleic acid encoding a fusion protein of any of the preceding embodiments.
  • the disclosure relates to a method of making a fusion protein according to any one of the preceding embodiments, the method comprising expressing a nucleic acid encoding the fusion protein in a host cell.
  • the host cell is engineered to improve the activity, cytoplasmic production, and/or stability of proteins having disulfide bonds.
  • the disclosed method of making a fusion protein yields a fusion protein having disulfide bonds for which the activity, cytoplasmic production, and/or stability of the fusion protein is increased by an amount selected from 2-fold, 5-fold, lO-fold, 20-fold, 50-fold, and lOO-fold as compared to the fusion protein produced by a non-engineered version of the same host cell.
  • the host cell is a non-mammalian cell. In some embodiments, the host cell is a yeast cell or a bacterial cell. In some embodiments, the host cell is an E. coli cell, an Archaebacterial cell, or an Actinobacterial cell. In some embodiments, the host cell is an E. coli strain that provides a cytoplasmic
  • the cytoplasmic environment is achieved by optimizing the thioredoxin and/or glutathione pathway, and/or by expressing cytosolic disulfide bond isomerase.
  • the host cell is an E. coli strain that constitutively expresses a chromosomal copy of a cytosolic disulfide bond isomerase.
  • the cytosolic disulfide bond isomerase is DsbC.
  • the E. coli strain is SHuffle® T7, SHuffle® T7 Express, SHuffle® Express, OrigamiTM, or Rosetta-
  • FIG.1A shows the protein design of a full-antibody-CD-CD fusion protein.
  • FIG. 1B shows the protein design and expression profile of a full-antibody- CD fusion protein expressed in mammalian cells.
  • FIG. 2A shows the vector design of an antigen-targeting domain-CD fusion protein.
  • FIG. 2C and FIG. 2D show the expression profile of several VHH-CD fusion proteins of the disclosure. 10: E. coli culture before induction. 15: E. coli culture 5 hours post- induction. Cytosol (C): the soluble fraction of cell lysate.
  • Inclusion body (I) the insoluble fraction of cell lysate. M: Marker.
  • FIG. 4A and FIG. 4B show size-exclusion chromatography analysis of several sdAb-CD fusion proteins.
  • FIG. 5 A and FIG. 5B show the cytosine deaminase (CDase) activity of several sdAb-CD fusion proteins.
  • FIG. 6A and FIG. 6B show EFISA assays demonstrating the binding ability of sdAb-CD fusion proteins to human VEGFR2 and human EGFR (FIG. 6A) and human HER2, HER3 and CEA (FIG. 6B).
  • OD optical density.
  • FIG. 7A and FIG. 7B show the purification profile from large scale purification of adAb-CD fusion proteins 3VGR19-CD-H (FIG. 7A) and 7D12- CDome3 (FIG.7B).
  • LS low speed supernatant;
  • Fl flow through 1 of Ni Sepharose column;
  • F2 flow through 2 of Ni-Sepharose column;
  • M marker;
  • Ql I st Q- Sepharose column;
  • Q2 2 nd Q-Sepharose column;
  • QF1 flow through of I st Q- Sepharose column;
  • QF2 flow through of 2 nd Q-Sepharose column;
  • XI fraction 1;
  • X2 fraction 2.
  • FIG. 8 shows the expression profile of sdAb-CD (3VGR19-CD) fusion proteins in SHuffle® T7 Express and T7 Express cells.
  • S supernatant (cytosol);
  • P pellet (inclusion body);
  • M marker;
  • Io E. coli culture before induction;
  • F E. coli culture 5 hours post-induction.
  • the band corresponding to the fusion protein is indicated with an arrow.
  • FIG. 9 A MDA-MB-231) and FIG. 9B (A431) show the results of cell- based cytotoxic assays with several fusion proteins of the disclosure in antigen expressing cells.
  • FIG.10 A shows the results of cell-based cytotoxic assays with the fusion proteins CDoem3-H and 7Dl2-CDoem3-H in EGFR-expressing cells.
  • 10B shows the results of cell-based cytotoxic assays with the fusion proteins CDoem3 and 7Dl2-CDoem3 in EGFR-expressing cells.
  • NP negative protein control (CDoem3-H).
  • FIG. 11A shows the tumor growth curve of the A431 xenograft model after treatment with 7Dl2-CDoem3-H and 7Dl2-CDoem3 in combination with 5- fluorocytosine (5-FC);
  • FIG. 11B shows the tumor weight of the A431 xenograft model after treatment with 7Dl2-CDoem3-H and 7Dl2-CDoem3 in combination with 5-FC.
  • FIG. 12 shows expression profile and functional analysis results for single mutation variants of 7D12-CDoem3-H.
  • FIG. 13A an FIG. 13B show expression profile and functional analysis results of multi-mutation variants of 7Dl2-CDoem3-H.
  • FIG. 14 shows a summary of T cell proliferation and IL-2 ELISpot responses of 7Dl2-CDoem3 and 7Dl2-CDoem3 variants.
  • FIG. 15 shows the cytosine deaminase activity and the binding ability of 7Dl2-CDoem3 and 7Dl2-CDoem3 variants to human EGFR.
  • the disclosure provides dual-function fusion proteins comprising a single-domain antibody (sdAb) or functional variant thereof with a cytosine deaminase (CD) or functional variant thereof.
  • the fusion proteins are made using the methods described herein with good biological activity and superior yields (e.g., about 1 g/L), amenable to commercial use.
  • the fusion proteins of the disclosure can be expressed in high yields as cytosolic proteins in E. coli, and the protein stability can be further improved in an E. coli strain that has been engineered to optimize disulfide bond formation in the cytoplasm.
  • compositions and methods of using the fusion proteins of the disclosure in the treatment of cancer and other proliferative diseases.
  • the disclosure demonstrates that various sdAb-CD fusion proteins according to the disclosure are stable and have cytotoxic effects on cancer cells.
  • Soluble proteins were detected by SDS-PAGE and the relative high purity of the fusion proteins is shown by SEC-HPLC.
  • the CD and sdAb portions of the fusion proteins both maintained their original function in all of the fusion proteins produced.
  • CD activity was demonstrated by a 5-FC-to-5-FU conversion assay and the binding of the fusion proteins to human VEGFR2, EGFR, HER3, HER2, or CEA was shown by
  • the sdAb-CD fusion proteins proved their ability to target and bind VEGFR2 and EGFR and convert non- toxic 5- FC to toxic 5-FU, thereby killing the antigen expressing cancer cells.
  • the sdAb-CD fusion proteins proved to be functional by inhibiting and suppressing tumor growth.
  • Fusion proteins of the disclosure using the methods described herein resulted in fusion proteins with good biological activity and superior yields (e.g., about 1 g/L), amenable to commercial use.
  • the disclosure also provides de-immunized sdAb-CD fusion proteins that are stable for production and which demonstrated CD activity and antigen binding activity.
  • “and/or” where used herein is to be taken as specific disclosure of each of the two specified features or components with or without the other.
  • the term“and/or” as used in a phrase such as“A and/or B” herein is intended to include“A and B,”“A or B,”“A” (alone), and“B” (alone).
  • the term“about” is understood as within a range of normal tolerance in the art, for example within two standard deviations of the mean (e.g., the stated value).“About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from context, all numerical values provided herein are modified by the term“about.”
  • compositions or methods provided herein can be combined with one or more of any of the other compositions and methods provided herein.
  • The“activity” of an enzyme is a measure of its ability to catalyze a reaction, i.e., to“function,” and may be expressed as the rate at which the product of the reaction is produced.
  • enzyme activity can be represented as the amount of product produced per unit of time or per unit of enzyme (e.g.,
  • a“cytosine deaminase activity,”“biological activity of cytosine deaminase,” or“functional activity of a cytosine deaminase” refers to an activity exerted by CD or a functional variant thereof, or by a fusion protein of the disclosure, on a CD substrate, as determined in vivo or in vitro according to standard techniques.
  • Assays for measuring CD activity are known in the art.
  • CD activity can be measured by determining the rate of conversion of 5-FC to 5-FU or cytosine to uracil.
  • the detection of 5-FC, 5-FU, cytosine, and uracil can be performed by the methods described in the Examples section, by chromatography, and/or by other methods known in the art.
  • polypeptide/protein or nucleic acid sequence that“consists essentially of’ a recited sequence may include one or more additional amino acids or nucleic acids, respectively, that do not destroy the biological activity of the recited sequence.
  • “fusion polypeptide” or“fusion protein” refers to a protein comprising two or more different polypeptides or active fragments thereof that are not naturally present in the same protein.
  • a fusion protein has a single contiguous polypeptide backbone, optionally with a peptide linker between any of the two or more different polypeptides. Fusion proteins can be prepared using conventional techniques in molecular biology to join the two or more genes in frame into a single nucleic acid sequence, and then expressing the nucleic acid in an appropriate host cell under conditions in which the fusion protein is produced.
  • “functional variant” refers to a variant of a polypeptide or protein having substantial or significant sequence identity to the polypeptide or protein and retaining at least one of the biological activities of the polypeptide or protein.
  • a functional variant of a polypeptide or protein can be prepared by means known in the art in view of the present disclosure.
  • a functional variant can include one or more modifications to the amino acid sequence of the polypeptide or protein.
  • the modifications change one or more physicochemical properties of the polypeptide or protein, for example, by improving the thermal stability of the polypeptide or protein, altering the substrate specificity, changing the optimal pH, reduce immunogenicity, and the like. In some embodiments, the modifications alter one or more of the biological activities of the polypeptide or protein, so long as they do not destroy or abolish all of the biological activities of the polypeptide or protein.
  • a functional variant of a polypeptide or protein comprises one or more of an amino acid substitution, preferably a conservative amino acid substitution, to the polypeptide or protein that does not significantly affect the biological activity of the polypeptide or protein.
  • Conservative amino acid substitutions include, but are not limited to, amino acid substitutions within the group of basic amino acids (arginine, lysine, and histidine), amino acid substitutions with the group of acidic amino acids (glutamic acid and aspartic acid), amino acid substitutions within the group of polar amino acids (glutamine and asparagine), amino acid substitutions within the group of hydrophobic amino acids (leucine, isoleucine, and valine), amino acid substitutions within the group of aromatic amino acids (phenylalanine, tryptophan, and tyrosine), and amino acid substitutions within the group of small amino acids (glycine, alanine, serine, threonine, and methionine).
  • Non-standard or unnatural amino acids may also or alternatively be used to substitute standard amino acid residues in a polypeptide or protein.
  • a functional variant of a polypeptide or protein comprises a deletion and/or insertion of one or more amino acids to the polypeptide or protein.
  • a functional variant of CD can include a deletion and/or insertion of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, or more amino acids to CD.
  • a functional variant of a sdAb can include a deletion and/or insertion of 1, 2,
  • a functional variant of a sdAb can include a deletion and/or insertion of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, or more amino acids to the framework (FR) region of the sdAb.
  • the functional variant of a polypeptide or protein comprises a deletion of the first methionine.
  • a functional variant of a polypeptide or protein comprises a substitution and a deletion and/or insertion to the parent protein.
  • the substitution is a conservative substitution and/or the deletion and/or insertion is a small deletion and/or small insertion.
  • VHH variable domain of heavy chain antibody
  • CD variable domain of heavy chain antibody
  • CD protein refers interchangeably.
  • nucleic acids or polypeptides refer to two or more sequences or subsequences that are the same or have a specified percentage of nucleotides or amino acid residues that are the same, when compared and aligned (introducing gaps, if necessary) for maximum correspondence, not considering any conservative amino acid substitutions as part of the sequence identity.
  • substantially identical refers to two or more sequences or subsequences that have a specified percentage of amino acid residues or nucleotides that are the same (i.e., at least about 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or higher identity over a specified region, when compared and aligned for maximum correspondence over a comparison window or designated region) as measured using a BLAST or BLAST 2.0 sequence comparison algorithms with default parameters described below, or by manual alignment and visual inspection.
  • the definition includes sequences that have deletions and/or additions, as well as those that have substitutions.
  • identity or substantial identity is determined over the entire length of the reference sequence.
  • identity can be determined over a region that is at least about 10 amino acids or nucleotides in length, at least about 25 amino acids or nucleotides in length, or over a region that is 50-100 amino acids or nucleotides in length.
  • the percent identity can be measured using sequence comparison software or algorithms or by visual inspection.
  • Various algorithms and software are known in the art that can be used to obtain alignments of amino acid or nucleotide sequences ⁇ see e.g. , Karlin et al., 1990, Proc. Natl. Acad. Sci.
  • Gapped BLAST can be used as described in Altschul et al., 1997, Nucleic Acids Res. 25:3389-3402.
  • BLAST-2 Altschul et al., 1996, Methods in Enzymology, 266:460-480
  • ALIGN ALIGN-2
  • ALIGN-2 Genetech, South San Francisco, Calif.
  • MegAlign DNASTAR
  • isolated when used to describe a protein or nucleic acid, refers to a molecule that is substantially free of other elements present in its natural environment. For instance, an isolated protein is substantially free of cellular material or other proteins from the cell or tissue source from which it is derived.
  • isolated also refers to preparations where the isolated protein is sufficiently pure to be administered as a pharmaceutical composition, or at least 70-80% (w/w) pure, more preferably, at least 80-90% (w/w) pure, even more preferably, 90-95% pure; and, most preferably, at least 95%, 96%, 97%, 98%, 99%, or 100% (w/w) pure.
  • “specifically binds” refers to an agent (e.g., sdAb or functional variant thereof) that recognizes and binds a molecule (e.g., VEGFR2, EGFR), but which does not substantially recognize and bind other molecules in a sample, for example, other molecules in a biological sample.
  • an agent e.g., sdAb or functional variant thereof
  • a molecule e.g., VEGFR2, EGFR
  • two molecules that specifically bind form a complex that is relatively stable under physiologic conditions. Specific binding is characterized by a high affinity and a low- to-moderate number of binding sites, as distinguished from nonspecific binding, which usually has a low affinity with a moderate-to-high number of binding sites.
  • the term“specifically binds to” or is“specific for” refers to measurable and reproducible interactions such as binding between a target and an antibody (e.g., sdAb or functional variant thereof), which is determinative of the presence of the target in the presence of a heterogeneous population of molecules inducing biological molecules.
  • a sdAb or functional variant thereof that specifically binds to a target is a sdAb or functional variant thereof that binds this target with greater affinity, avidity, more readily, and/or with greater duration than it binds to other targets.
  • the extent of binding of a sdAb or functional variant thereof to an unrelated target is less than about 10% of the binding of the sdAb or functional variant thereof to the target as measured, e.g., by a radioimmunoassay (RIA).
  • a sdAb or functional variant thereof that specifically binds to a target has a dissociation constant of (KD) of ⁇ 1x10 6 M, ⁇ lxl0 7 M, ⁇ lxl0 8 M, ⁇ 1c10 9 M, or ⁇ lxlO 10 M, ⁇ 1c10 h M, ⁇ lxl0 12 M.
  • a sdAb or functional variant thereof specifically binds to an epitope on a protein that is conserved among the protein from different species.
  • specific binding can include, but does not require, exclusive binding (i.e., it can bind to only one protein).
  • subject refers to a mammal, including, but not limited to, a human or non-human mammal, such as a bovine, equine, canine, ovine, or feline.
  • Ranges provided herein are understood to be shorthand for and thus encompass all of the values within the range.
  • a range of 1 to 50 is understood to include any number, combination of numbers, or sub-range chosen from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50, including non-integers thereof.
  • Neoplasm refers to an abnormal mass of tissue containing neoplastic cells. Neoplasms and tumors may be benign, premalignant, or malignant.
  • cancer or“malignant neoplasm” refers to a cell that displays uncontrolled growth, invasion upon adjacent tissues, and often metastasis to other locations of the body. This includes hematologic and lymphoid cancers.
  • binding affinity generally refers to the strength of the sum total of non-co valent interactions between a single binding site of a molecule (e.g., of a sdAb) and its binding partner (e.g., an antigen). Unless indicated otherwise, as used herein,“binding affinity,”“bind to,”“binds to,” or“binding to” refers to an intrinsic binding affinity that reflects a 1 :l interaction between members of a binding pair (e.g., antibody Fab fragment and antigen).
  • the affinity of a molecule X for its partner Y can generally be represented by the dissociation constant (KD). Affinity can be measured by common methods known in the art, including those described herein.
  • binding affinity antibodies generally bind antigen slowly and tend to dissociate readily, whereas high- affinity antibodies generally bind antigen faster and tend to remain bound longer.
  • a variety of methods of measuring binding affinity are known in the art, any of which can be used for purposes of the present invention. Specific illustrative and exemplary embodiments for measuring binding affinity, e.g., binding strength are described in the following. [00102] Various publications, articles, and patents are cited or described in the background and throughout the specification; each of these references is herein incorporated by reference in its entirety. Discussion of documents, acts, materials, devices, articles, or the like which have been included in the present specification is for the purpose of providing context for the invention. Such discussion is not an admission that any or all of these matters form part of the prior art with respect to any inventions disclosed or claimed.
  • N is a single-domain antibody (sdAb) or functional variant thereof
  • C is a cytosine deaminase (CD) protein or a functional variant thereof.
  • the fusion protein consists essentially of formula I. In some embodiments, the fusion protein consists of formula I. In some embodiments, the fusion protein consists essentially of formula II. In some embodiments, the fusion protein consists of formula II.
  • the fusion protein comprises formula I such that the C-terminus of the peptide linker or the C-terminus of the sdAb or functional variant thereof is fused to the N-terminus of the CD protein or functional variant thereof.
  • the peptide linker is not present and the C- terminus of the sdAb or functional variant thereof is fused to the N-terminus of the CD protein or functional variant thereof.
  • the peptide linker is present and the C-terminus of the sdAb or functional variant thereof is fused to the N- terminus of the peptide linker, and the C-terminus of the peptide linker is fused to the N-terminus of the CD protein or functional variant thereof.
  • the fusion protein comprises formula II such that the C-terminus of the peptide linker or the C-terminus of the CD protein or functional variant thereof is fused to the N-terminus of the sdAb or functional variant thereof.
  • the peptide linker is not present and the C- terminus of the CD protein or functional variant thereof is fused to the N-terminus of the sdAb or functional variant thereof.
  • the peptide linker is present and the C-terminus of the CD protein or functional variant thereof is fused to the N- terminus of the peptide linker, and the C-terminus of the peptide linker is fused to the
  • N-terminus of the sdAb or functional variant thereof N-terminus of the sdAb or functional variant thereof.
  • a sdAb comprises a single chain with a single variable domain having three complementarity determining regions (CDRs).
  • Single-domain antibodies traditionally comprise the variable fragments of Camelid heavy-chain only antibodies (HcAbs), i.e., the variable domain of the heavy-chain of heavy-chain antibodies,
  • VHH VHH.
  • Some VHH polypeptides are also referred to as the trademarked name Nanobody® (Nb;Ablynx).
  • the use of the term nanobody does not limit the single-domain antibody to a Nanobody® provided by Ablynx.
  • the sdAb or functional variant thereof is selected from heavy chain only IgG class antibodies of camels, alpacas, or llamas.
  • the sdAb or functional variant thereof is an engineered polypeptide generated by CDR grafting.
  • the sdAb or functional variant thereof is generated by replacing all or some of the CDR region of the camelid derived sdAbs with the CDR region of other known antibodies having desired targets.
  • the sdAb or functional variant thereof is a recombinant derivative of heavy-chain-only antibodies found in sharks. In some embodiments, the sdAb or functional variant thereof is synthetically generated using techniques that are well known in the art. In certain embodiments, a sdAb or functional variant thereof is a human sdAb (Do mantis, Inc., Waltham, Mass.; see, e.g., U.S. Pat. No. 6,248,516 Bl).
  • the sdAb or functional variant thereof is a humanized VHH from a Camelid.
  • the term "humanized" sdAb means a sdAb that has had one or more amino acid residues in the amino acid sequence of the naturally occurring VHH sequence replaced by one or more amino acid residues that occur at the corresponding position in a VH domain from a conventional four- chain antibody from a human. This substitution can be performed by methods that are well known in the art.
  • the framework regions (FRs) of the sdAbs can be replaced by human variable FRs.
  • the CDRs are of primary importance for epitope recognition of a sdAb or functional variant thereof. Changes may be made to the amino acid residues that make up the CDRs without interfering with the ability of the sdAb or functional variant thereof to recognize and bind its cognate epitope. For example, changes that do not affect target epitope recognition, yet increase the binding affinity of the sdAb or functional variant thereof for the epitope, may be made. In some embodiments, these changes are conservative amino acid substitutions and/or small deletions or small insertions.
  • the sdAbs or functional variants thereof comprise the variable domain of any one of a heavy chain-only IgG class of antibodies.
  • the single variable domain comprises three complementarity-determining regions (CDRs).
  • a sdAb or functional variant thereof can be an immunoglobulin and/or polypeptide with the (general) structure FR1-CDR1-FR2-CDR2-FR3-CDR3- FR4, in which FR1, FR2, FR3, and FR4 refer to framework regions 1, 2, 3, and 4, respectively, and in which CDR1, CDR2, and CDR3 refer to complementarity determining regions 1, 2, and 3, respectively.
  • the numbering of the amino acid residues of a sdAb or functional variant thereof is according to the general numbering for VH domains given by Rabat et al. ("Sequence of proteins of immunological interest," US Public Health Services, NIH Bethesda, Md., Publication No. 91).
  • FR1 of a sdAb comprises the amino acid residues at positions 1-30
  • complementarity-determining region 1 (CDR1) of a sdAb or functional variant thereof comprises the amino acid residues at positions 31-35
  • FR2 of a sdAb or functional variant thereof comprises the amino acids at positions 36-49
  • CDR2 of a sdAb or functional variant thereof comprises the amino acid residues at positions 50-65
  • FR3 of a sdAb or functional variant thereof comprises the amino acid residues at positions 66-94
  • CDR3 of a sdAb or functional variant thereof comprises the amino acid residues at positions 95-102
  • FR4 of a sdAb or functional variant thereof comprises the amino acid residues at positions 103-113.
  • the sdAb or functional variant thereof is a half- life extended sdAb. Methods of increasing the half-life of polypeptides are well known in the art.
  • the effectiveness of the fusion proteins of the present disclosure as therapeutic agents depends on the selection of an appropriate sdAb target.
  • the target may be of any kind presently known, or that becomes known, and includes peptides and non-peptides (e.g., cell surface lipids, glycan or other post-translational modifications).
  • the sdAbs or functional variants thereof of the disclosure bind to extracellular targets on the surface of cancer cells.
  • the sdAb or functional variant thereof binds to a target, wherein the target is selected from a cell membrane molecule, a secreted molecule, and an intracellular molecule.
  • the target is selected from the group consisting of EGFR, 5T4, A33, AFP, Beta-catenin, BRCA1, BRCA2, C242, CCR4, CD152, CD19, CD20, CD200, CD22, CD221, CD23, CD30, CD3, CD37, CD40, CD44, CD5, CD51, CD52, CD56, CD64, CD74, CD80, CDCP1, c-KIT, COX-2, cMET, CSF1R, CTEA-4, EGF2, ErbB2, ErbB3, FGFR1, FGFR2, FGFR3, FET3, HER2, HER3, HIF- Ia, HEA-DR, IGF-IR, mTOR, NPC-1C, P53, PDGFRa, PDGFR , PLGF, PSA, RGMa, RoN, TNF, TP53, TPD52, VEGFR1, VEGFR2, VEGFR3, CA-IX, anb3, a5b1, F
  • the target is selected from the group consisting of EGFR, c-KIT, cMET, HER2, HER3, FGFR1, FGFR2, FGFR3, IGF-IR, P53, PDGFRa, VEGFR1, VEGFR2, VEGFR3, CA-IX, anb3, a5b1, MUC16,
  • carcinoembryonic antigen CEA
  • prostate-specific membrane antigen CAA
  • Cancer-testis (CT) antigens e.g., NY-ESO-l, MAGE- A3, MAGE-A1
  • Mesothelin EpCAM
  • integrin a6b4 CEACAM6, integrin a3b1, integrin anb3, PD-L1, AXL, CDH6, DLL3, EDNRB, EFNA4, NEPP3, EPHA2, FOLR1, LewisY, GPNMB, GUCY2C, HAVCR1, Integrin a, LYPD3, MUC1, NECTIN4, NOTCH3, PTK7, SLC34A2, SLC39A6, SLC44A4, SLITRK6, STEAP1, TACSTD2, TPBG, TIM-l, GD2, and nicotinic acetylcholine receptor (nAChR).
  • CEA carcinoembryonic antigen
  • CT Cancer-testis
  • the target is VEGFR2, EGFR, CEA, HER2, or HER3.
  • the sdAb or functional variant thereof of a fusion protein of the disclosure targets EGFR.
  • the sdAb or functional variant thereof is derived from VHH122, described in J. Biomol. Screen. 2009 Jan;l4(l):77-85.
  • the sdAb or functional variant thereof is derived from 7Dl2, described as Structure 21, 1214-1224, July 2, 2013. PDB:
  • the sdAb or functional variant thereof of a fusion protein of the disclosure targets VEGFR2.
  • the sdAb or functional variant thereof is derived from 3VGR19, described in Mol. Immunol. 2012 Feb;50(l-2):35-41.
  • the sdAb or functional variant thereof is derived from 4VGR17, described in Mol. Immunol. 2012 Feb;50(l-2):35-41.
  • the sdAb or functional variant thereof is derived from 4VGR38, described in Mol. Immunol. 2012 Feb;50(l-2):35-41.
  • the sdAb or functional variant thereof of a fusion protein of the disclosure targets HER2.
  • the sdAb or functional variant thereof is derived from 2D3, 5F7, or 47D5, described in U.S. Patent
  • the sdAb or functional variant thereof of a fusion protein of the disclosure targets HER3.
  • the sdAb or functional variant thereof is derived from BCD090-M2 (PDB ID: 6EZW), described in Version 2. FlOOORes. 2018; 7: 57.
  • the sdAb or functional variant thereof of a fusion protein of the disclosure binds CEA.
  • the sdAb or functional variant thereof is derived from ABS29544.1 or NbCEA5, described in US20160280795A1, FEBS J. 2009 Jul;276(14):3881-93 and J Nucl Med. 2010 Jul;51 (7) : 1099- 106.
  • the biological activity of a sdAb or functional variant thereof of a fusion protein of the disclosure can be assessed by, for example, determining its binding affinity to a target or an epitope thereof.
  • the affinity of the sdAb or functional variant thereof of the fusion protein for a target or an epitope thereof can be, for example, from about 1 picomolar (pM) to about 100 micromolar (mM) (e.g., from about 1 picomolar (pM) to about 1 nano molar (nM), from about 1 nM to about 1 micromolar (mM), or from about 1 pM to about 100 pM).
  • the sdAb or functional variant thereof of the fusion protein can bind to a target (e.g., VEGFR2, EGFR, HER2, HER3, or CEA) with a KD less than or equal to 1 nanomolar (e.g., 0.9 nM, 0.8 nM, 0.7 nM, 0.6 nM, 0.5 nM, 0.4 nM, 0.3 nM, 0.2 nM, 0.1 nM, 0.05 nM, 0.025 nM, 0.01 nM, 0.001 nM, or a range defined by any two of the foregoing values).
  • a target e.g., VEGFR2, EGFR, HER2, HER3, or CEA
  • 1 nanomolar e.g., 0.9 nM, 0.8 nM, 0.7 nM, 0.6 nM, 0.5 nM, 0.4 nM, 0.3 nM, 0.2 nM, 0.1 nM,
  • the sdAb or functional variant thereof of the fusion protein of the disclosure can bind to the target with a KD less than or equal to 200 pM (e.g., 190 pM, 175 pM, 150 pM, 125 pM, 110 pM, 100 pM, 90 pM, 80 pM, 75 pM, 60 pM, 50 pM, 40 pM, 30 pM, 25 pM, 20 pM, 15 pM, 10 pM, 5 pM, 1 pM, or a range defined by any two of the foregoing values).
  • 200 pM e.g., 190 pM, 175 pM, 150 pM, 125 pM, 110 pM, 100 pM, 90 pM, 80 pM, 75 pM, 60 pM, 50 pM, 40 pM, 30 pM, 25 pM, 20 pM, 15 pM, 10 p
  • the affinity of a sdAb or functional variant thereof of a fusion protein disclosed herein for an antigen or epitope of interest can be measured using any art-recognized assay.
  • Such methods include, for example, fluorescence activated cell sorting (FACS), separable beads (e.g., magnetic beads), surface plasmon resonance (SPR), solution phase competition
  • sdAbs or functional variants thereof
  • nucleic acids used to make the fusion proteins of the disclosure can be prepared as described by the below Examples or by any method known to one of ordinary skill in the art.
  • the sdAb or functional variant thereof comprises, consists essentially of, or consists of a CDR1 selected from the group consisting of SEQ ID NOs: 28, 31, and 34; a CDR2 selected from the group consisting of SEQ ID NOs: 29, 32, and 35; and a CDR3 selected from the group consisting of SEQ ID NOs: 30, 33, and 36.
  • the sdAb or functional variant thereof comprises, consists essentially of, or consists of a CDR1 selected from the group consisting of SEQ ID NOs: 37 and 40, a CDR2 selected from the group consisting of SEQ ID NOs: 38 and 41, and a CDR3 selected from the group consisting of SEQ ID NOs: 39 and 42.
  • the sdAb or functional variant thereof comprises, consists essentially of, or consists of a CDR1 selected from the group consisting of SEQ ID NOs: 199, 202, and 205; a CDR2 selected from the group consisting of SEQ ID NOs: 200, 203, and 206; and a CDR3 selected from the group consisting of SEQ ID NOs: 201, 204, and 207.
  • the sdAb or functional variant thereof comprises, consists essentially of, or consists of a CDR1 of SEQ ID NO: 208, a CDR2 of SEQ ID NO: 209, and a CDR3 of SEQ ID NO: 210.
  • the sdAb or functional variant thereof comprises, consists essentially of, or consists of a CDR1 selected from the group consisting of SEQ ID NOs: 211 and 214, a CDR2 selected from the group consisting of SEQ ID NOs: 212 and 215, and a CDR3 selected from the group consisting of SEQ ID NOs: 213 and 216.
  • the sdAb or functional variant thereof is selected from the group of anti-VEGFR2 sdAbs disclosed in the Examples, namely 3VGR19 (SEQ ID NO: 23), 4VGR17 (SEQ ID NO: 24), and 4VGR38 (SEQ ID NO:
  • the sdAb or functional variant thereof is selected from the group of anti-EGFR sdAbs disclosed in the Examples, namely VHH122 (SEQ ID NO:
  • the sdAb or functional variant thereof is selected from the group of anti-HER2 sdAbs disclosed in the Examples, namely 2D3 (SEQ ID NO: 69), 5F7 (SEQ ID NO: 70) and 47D5 (SEQ ID NO: 71). In some embodiments, the sdAb or functional variant thereof is selected from the group of anti-HER3 sdAbs disclosed in the Examples, namely BCD090-M2 (SEQ ID NO: 75).
  • the sdAb or functional variant thereof is selected from the anti-CEA sdAbs disclosed in the Examples, namely anti-CEA sdAb (ABS29544.1) (SEQ ID NO: 77) and NbCEA5 (SEQ ID NO: 79).
  • any of the sdAbs or functional variants thereof disclosed herein are fused with a yeast CD protein or functional variant thereof comprising the amino acid sequence of SEQ ID NO: 21 (wild type CD, without the N- terminal methionine), SEQ ID NO: 22 (a variant of SEQ ID NO: 21 with point mutations A22L/V107I/I139L), SEQ ID NO: 186 (wild type CD, including the N- terminal methionine), SEQ ID NO: 187 (a variant of SEQ ID NO: 186 with point mutations A23L/V108I/I140L), or a functional variant of any of the foregoing amino acid sequences.
  • the fusion proteins comprise a histidine tag (HIS-tag) at the C-terminus, e.g., a 6-HIS tag (SEQ ID NO: 6).
  • the fusion protein is linked to the HIS-tag via a peptide linker (e.g., GSS).
  • the sdAb or functional variant thereof of a fusion protein of the disclosure can be partially or fully humanized for use in prophylaxis and/or therapy of a condition that is positively associated with the presence of the sdAb’s target.
  • humanization involves replacing all or some of the camelid derived framework and variable regions of a sdAb or functional variant thereof with a human counterpart sequence, with the aim being to reduce
  • the FR residues of the camelid immunoglobulin are replaced by corresponding human residues.
  • the sdAb or functional variant thereof comprises one or more mutations on the following T cell epitopes:
  • the sdAb or functional variant thereof comprises a sequence X 1 X 2 QX 3 X 4 GX 5 LRL modified from Epitope 1 (SEQ ID NO:
  • Xi can be substituted by V
  • X 2 can be substituted by A
  • X3 can be substituted by V
  • X 4 can be substituted by D
  • X5 can be substituted by D or E.
  • the sdAb or functional variant thereof comprises a sequence LX 1 X 2 EDX 3 X 4 X 5 Y modified from Epitope 2 (SEQ ID NO: 64), wherein Xi can be substituted by R, A, D, S, or T; X 2 can be substituted by A, D, or E; X 3 can be substituted by D, E, G, H, or Q; X 4 can be substituted by D or E; and/or X 5 can be substituted by V, A, T, R, Q, or N.
  • the sdAb or functional variant thereof comprises a sequence XiYYCAAAAGS modified from Epitope 3 (SEQ ID NO: 65), wherein Xi can be substituted by V, A, T, R, Q, or N.
  • the sdAb or functional variant thereof comprises a sequence X 1 X 2 QX 3 X 4 GSLRL modified from Epitope 1 (SEQ ID NO:
  • the sdAb or functional variant thereof comprises a sequence LX1X2EDTAX5Y modified from Epitope 2 (SEQ ID NO: 64), wherein Xi can be substituted by R or T; X2 can be substituted by A; and/or X5 can be substituted by V or R.
  • the sdAb or functional variant thereof comprises a sequence XiYYCAAAAGS modified from Epitope 3 (SEQ ID NO: 65), wherein Xi can be substituted by V or R.
  • the sdAb or functional variant thereof comprises a FR1 sequence with a sequence ESGGGX1X2QX3GGSL, wherein Xi is S or V, X 2 is V or A, and X3 is A, T, or V.
  • the sdAb or functional variant thereof comprises a FR3 sequence comprising a modified sequence MNSLX1X2EDTAX3YYCAA, wherein Xi is K, R, or T; X 2 is P or A; and X 3 is R or V.
  • sdAbs or functional variant thereof are derived from HCAb produced by immunizing a transgenic mouse with a target peptide in which endogenous murine antibody expression has been eliminated and human transgenes have been introduced.
  • HCAb mice are disclosed in U.S. Pat. No. 8,883,150, U.S. Pat. No. 8,921,524, U.S. Pat. No. 8,921,522, U.S. Pat. No. 8,507,748, U.S. Pat. No. 8,502,014, US 2014/0356908, US2014/0033335, US2014/0037616, US2014/0356908, US2013/0344057, US2013/0323235,
  • one method for obtaining sdAbs or functional variants thereof includes (a) immunizing a Camelid with one or more antigens, (b) isolating peripheral lymphocytes from the immunized Camelid, obtaining the total RNA and synthesizing the corresponding cDNAs, (c) constructing a library of cDNA fragments encoding sdAb domains, (d) transcribing the sdAb domain-encoding cDNAs obtained in step (c) to mRNA using PCR, converting the mRNA to ribosome or phage display format, and selecting the sdAb domain by ribosome display or phage display panning, and (e) expressing the sdAb domain in a suitable vector and, optionally, purifying the expressed sdAb domain.
  • nanobodies in particular, VHH sequences and partially humanized nanobodies
  • VHH sequences and partially humanized nanobodies can in particular be characterized by the presence of one or more "Hallmark residues" in one or more of the framework sequences.
  • a further description of the nanobodies, including humanization and/or camelization of nanobodies, as well as other modifications, parts or fragments, derivatives or“nanobody fusions,” multivalent constructs (including some non limiting examples of linker sequences) and different modifications to increase the half-life of the nanobodies and their preparations can be found, e.g., in WO
  • linker refers to an oligo- or polypeptide region from about 1 to 100 amino acids in length, which links together polypeptides of the fusion proteins of the disclosure (e.g., the sdAb or functional variant thereof and the CD protein or functional variant thereof).
  • a fusion protein of the disclosure may comprise one or more than one linker.
  • Linkers may be composed of flexible residues like glycine and serine so that the adjacent protein domains are free to move relative to one another. In some embodiments, the linker comprises 1 to 20, 1 to 15, 1 to 10, or 1 to nine amino acids.
  • the linker comprises from one to nine amino acids, e.g., one, two, three, four, five, six, seven, eight, or nine amino acids. In some embodiments, the linker is a peptide that ranges from about 6 to about 30 amino acids in length. In aspects of these
  • the peptide linker can be, e.g., at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, at least 14, at least 15, at least 16, at least 17, at least 18, at least 19, at least 20, at least 21, at least 22, at least 23, at least 24, at least 25, at least 26, at least 27, at least 28, at least 29 or 30 amino acids in length.
  • the peptide linker can be, e.g., at most
  • the peptide linker can be, e.g., about 6 to about 8, about 6 to about 10, about 6 to about 12, about 6 to about 14, about 6 to about 16, about 6 to about 18, about 6 to about 20, about 6 to about 22, about 6 to about 24, about 6 to about 26, about 6 to about 28, about 6 to about 30, about 8 to about 10, about 8 to about 12, about 8 to about 14, about 8 to about 16, about 8 to about 18, about 8 to about 20, about 8 to about 22, about 8 to about 24, about 8 to about 26, about 8 to about 28, about 8 to about 30, about 10 to about 12, about 10 to about 14, about 10 to about 16, about 10 to about 18, about 10 to about 20, about 10 to about 22, about 10 to about 24, about 10 to about 26, about 10 to about 28, about 10 to about 30, about 12 to about 14, about 12 to about 16, about 12 to about 18, about 12 to about 20, about 12 to about 22, about 12 to about 24, about 12 to about 26, about 12 to about 28, about 12 to about 30, about 14 to about 16, about 14 to about 18, about 14, about 14, about 14, to about 16, about 14 to about 18, about 18, about 14 to
  • the linker can comprise natural or non- natural amino acids.
  • the linker comprises any amino acid, combinations of different amino acids, or the same amino acid.
  • the linkers can be peptide sequences of different kinds linked together, one or more times in a row, or alternating with other sequences.
  • the linkers can also be peptide sequences that are repeated. In some embodiments, an entire peptide sequence is repeated 1 to 50 times. Longer linkers may also be used when it is desirable to ensure that two adjacent domains do not sterically interfere with one another.
  • the linker is one or more of GSGG (SEQ ID NO: 2), GGGGSGGGS (SEQ ID NO: 3), and/or one or more GSG.
  • the linker is KESGSVSSEQLAQFRSLD (SEQ ID NO: 4) or EGKSSGSGSESKST (SEQ ID NO: 5).
  • the linker is (GGGGS)3 (SEQ ID NO: 188).
  • Exemplary amino acid residues for use in linkers include glycine, threonine, arginine, serine, alanine, asparagine, glutamine, aspartic acid, proline, glutamic acid, and/or lysine.
  • linkers that can be used for fusion proteins are well known in the art and some can be found in Chen, X. et al., Adv Drug Deliv. Rev. 2013 Oct 15; 65(10): 1357-1369, incorporated herein by reference in its entirety. Additional linkers suitable for fusion proteins of the present disclosure can also be found in Klein et al., Protein Eng. Des. Sel. 2014 Oct; 27(10): 325-330, incorporated herein by reference in its entirety.
  • a fusion protein of the disclosure comprises one linker between a sdAb or functional variant thereof and a CD protein or functional variant thereof. In some embodiments, the fusion protein comprises at least one linker between a sdAb or functional variant thereof and a CD protein or functional variant thereof. For example, in some aspects, the fusion protein comprises two linkers between a sdAb or functional variant thereof and a CD protein or functional variant thereof.
  • a sdAb or functional variant thereof and a CD protein or functional variant thereof are fused directly (e.g., having no connecting linker).
  • Cytosine deaminase is an enzyme that is able to convert the relatively harmless 5-fluorocytosine (5-FC) prodrug into 5-fluorouracil (5-FU), which is a cytotoxic compound, in particular when it is converted to 5-fluorouridine 5’- monophosphate (5-FdUMP).
  • fusion proteins of the disclosure will bind to cells that express the target of the sdAbs or functional variants thereof of the disclosure, and the CD protein or functional variant thereof of the fusion protein will convert 5-FC into 5-FU, thereby killing the target cells.
  • the target cells are cancer cells.
  • the target cells are killed through a bystander effect. Anticancer Res. 1998 Sep-Oct;l8(5A):3399-406; Am J Cancer Res. 2015; 5(9): 2686-2696.
  • the CD or functional variant thereof may be yeast CD or a functional variant thereof. In some embodiments, the CD or functional variant thereof may be a bacterial CD or a functional variant thereof. In some embodiments, the CD or functional variant thereof is E. coli cytosine deaminase or a functional variant thereof. For example, in some embodiments, the CD or functional variant thereof is an E. coli cytosine deaminase represented by NCBI Reference Sequence: NP_414871.1. In some embodiments, the CD or functional variant thereof is a yeast cytosine deaminase represented by GenBank Accession No. AAB67713.1. The FCY1 gene of Saccharomyces cerevisiae ( S .
  • the CD protein or functional variant thereof comprises the sequence of SEQ ID NO: 21. In certain embodiments, the CD protein or functional variant thereof comprises the sequence of SEQ ID NO: 186. In certain embodiments, the sequence corresponding to cytosine deaminase contains one or more alterations. In some embodiments, the alterations result in a functional variant of a wild-type CD. Preferably, the alterations in the CD domain are stabilizing mutations.
  • the functional variant of CD comprises the sequence of SEQ ID NO: 22, having A22L/V 107I/1139L compared to SEQ ID NO: 21. In some embodiments, the functional variant of CD comprises the sequence of SEQ ID NO: 187, having A23L/V 108 I/I 140 L compared to SEQ ID NO: 186.
  • the disclosure also provides fusion proteins comprising a CD polypeptide that comprises a sequence that is at least 80%, 90%, 95%, 98% or 99% identical to SEQ ID NO: 21, 22, 186, or 187, wherein the polypeptide has cytosine deaminase activity and thus is called a“functional variant.”
  • the functional variant of CD protein can be a de-immunized form to reduce immunogenicity.
  • the CD protein or functional variant thereof comprises one or more mutations on the following T cell epitopes:
  • the CD protein or functional variant thereof comprises a sequence X 1 X 2 X 3 LSPCD X 4 modified from Epitope 4 (SEQ ID NO: 66), wherein Xi can be substituted by A or H, X 2 can be substituted by D, X 3 can be substituted by E, and X4 can be substituted by N, A, K, or Q.
  • the CD protein or functional variant thereof comprises a sequence XiCTGAIIMY modified from Epitope 5 (SEQ ID NO: 67), wherein Xi can be substituted by N, A, K, or Q.
  • the CD protein or functional variant thereof comprises a sequence X 1 X 2 X 3 VDDERCKK modified from Epitope 6 (SEQ ID NO: 68), wherein Xi can be substituted by A or T, X 2 can be substituted by A, L, I, or T, and X 3 can be substituted by A or T.
  • the CD protein or functional variant thereof comprises a sequence X1X2VVDDERCKK modified from Epitope 6 (SEQ ID NO: 68), wherein Xi can be substituted by A, X 2 can be substituted by T.
  • CD functional variants are variants of SEQ ID NOs: 21 or 22, wherein the variants comprise at least one mutation selected from Y84A, Y84H, T85D, T86E, M92N, M92A, M92K, M92Q, V128A, V128T, V129A, V129L, V129I, V129T, V130A, and V130T.
  • CD functional variants are variants of SEQ ID NOs: 186 or 187, wherein the variants comprise at least one mutation selected from Y85A, Y85H, T86D, T87E, M93N, M93A, M93K, M93Q, VI 29 A, V129T, V130A, V130L, V130I, V130T, V131A, and V131T.
  • the functional variant of the CD protein is selected from the group consisting of SEQ ID NOs: 22, 187, 189, 190, 191, 192, 193, and 194. In certain embodiments, the functional variant of the CD protein is selected from the group consisting of SEQ ID NOs: 22, 189, 191, and 193.
  • cytosine deaminase activity can be measured by determining the rate of conversion of 5-FC to 5-FU or cytosine to uracil.
  • the detection of 5-FC, 5-FU, cytosine, and uracil can be performed by the methods described in the Examples section, by chromatography, and/or by other methods known in the art.
  • N is a single-domain antibody (sdAb) or functional variant thereof
  • C is a cytosine deaminase (CD) protein or a functional variant thereof.
  • the fusion protein consists essentially of formula I. In some embodiments, the fusion protein consists of formula I. In some embodiments, the fusion protein consists essentially of formula II. In some embodiments, the fusion protein consists of formula II.
  • the fusion protein comprises formula I such that the C-terminus of the peptide linker or the C-terminus of the sdAb or functional variant thereof is fused to the N-terminus of the CD protein or functional variant thereof.
  • the peptide linker is not present and the C- terminus of the sdAb or functional variant thereof is fused to the N-terminus of the
  • the peptide linker is present and the C-terminus of the sdAb or functional variant thereof is fused to the N- terminus of the peptide linker, and the C-terminus of the peptide linker is fused to the N-terminus of the CD protein or functional variant thereof.
  • the fusion protein comprises formula II such that the C-terminus of the peptide linker or the C-terminus of the CD protein or functional variant thereof is fused to the N-terminus of the sdAb or functional variant thereof.
  • the peptide linker is not present and the C- terminus of the CD protein or functional variant thereof is fused to the N-terminus of the sdAb or functional variant thereof.
  • the peptide linker is present and the C-terminus of the CD protein or functional variant thereof is fused to the N- terminus of the peptide linker, and the C-terminus of the peptide linker is fused to the N-terminus of the sdAb or functional variant thereof.
  • the disclosure also provides fusion proteins comprising sdAbs— directed against extracellular target antigens, including, but not limited to, any of the target antigens described herein— fused to any of the cytosine deaminases described herein.
  • the fusion protein comprises the amino acid sequence of SEQ ID NOs: 7, 9, 11, 13, 15, 17, or amino acids 1-297 of any of the foregoing sequences.
  • the fusion protein consists essentially of the amino acid sequence of SEQ ID NOs: 7, 9, 11, 13, 15, 17, or amino acids 1-297 of any of the foregoing sequences.
  • the fusion protein consists of the amino acid sequence of SEQ ID NOs: 7, 9, 11, 13, 15, 17, or amino acids 1-297 of any of the foregoing sequences.
  • the fusion protein comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 17, 19, and 93-185. In some embodiments, the fusion protein consists essentially of an amino acid sequence selected from the group consisting of SEQ ID NOs: 17, 19, and 93-185. In some embodiments, the fusion protein consists of an amino acid sequence selected from the group consisting of SEQ ID NOs: 17, 19, and 93-185.
  • the fusion protein comprises amino acids 1-297 of an amino acid sequence selected from the group consisting of SEQ ID NOs: 93- 181. In some embodiments, the fusion protein consists essentially of amino acids 1- 297 of an amino acid sequence selected from the group consisting of SEQ ID NOs: 93-181. In some embodiments, the fusion protein consists of amino acids 1-297 of an amino acid sequence selected from the group consisting of SEQ ID NOs: 93-181.
  • the fusion protein comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 19, 182, 183, 184, and 185. In some embodiments, the fusion protein consists essentially of an amino acid sequence selected from the group consisting of SEQ ID NO: 19, 182, 183, 184, and 185. In some embodiments, the fusion protein consists of an amino acid sequence selected from the group consisting of SEQ ID NO: 19, 182, 183, 184, and 185.
  • the disclosure also provides for fusion proteins comprising more than one sdAb or functional variant thereof or CD protein or functional variant thereof.
  • the fusion protein may have the following formula III or IV:
  • CD cytosine deaminase
  • the fusion protein may have the following formula:
  • N1 and N2 may be the same or different, and wherein any of Ll, L2, and L3 may be the same or different.
  • the fusion protein is a bivalent fusion protein comprising two different sdAbs or functional variants thereof (i.e., it binds two different targets or two different epitopes in the same target). In some embodiments, the fusion protein is a monovalent fusion protein.
  • the fusion proteins of the disclosure can be further fused with moieties, e.g., peptide tags, for ease in purification, see e. g. , WO 93/21232; EP 439,095; Naramura et al., Immunol Lett 39:91 (1994); U.S. Pat. No. 5,474,981; Gillies et al., Proc Natl Acad Sci USA 89:1428 (1992); and Fell et al., J Immunol 146:2446 (1991).
  • the peptide tag is a histidine (HIS) tag.
  • the peptide tag is a hexa-histidine peptide (SEQ ID NO: 6).
  • the hexa-histidine tag may be the tag provided in a pQE vector (QIAGEN, Inc., Chatsworth, Calif.) or in another vector, many of which are commercially available, Gentz et al., Proc Natl Acad Sci USA 86:821 (1989).
  • Other peptide tags useful for purification include, but are not limited to, the“HA” tag, which corresponds to an epitope derived from the influenza hemagglutinin protein (Wilson et al., Cell 37:767 (1984)) and the“FLAGTM” tag.
  • the peptide tag can be located at the N-terminus of the fusion protein, the C-terminus of the fusion protein, or in between functional domains (e.g., between sdAb and CD or functional variant(s) thereof) of the fusion protein.
  • the peptide tag can be connected to the fusion protein by a peptide linker.
  • the peptide linker connecting the fusion protein and tag e.g., HIS-tag
  • the disclosure further encompasses fusion proteins that are conjugated to chemical moieties including, for example, cytotoxic/chemotherapeutic moieties and/or radiolabels.
  • chemical moieties including, for example, cytotoxic/chemotherapeutic moieties and/or radiolabels.
  • Any of the cytotoxic agents and chemotherapeutic agents described herein for combination treatment with the fusion proteins of the disclosure can be chemically conjugated to the fusion proteins of the disclosure.
  • the cytotoxic agent or chemotherapeutic agent is covalently conjugated to the fusion protein.
  • the cytotoxic agent of chemotherapeutic agent is non-covalently conjugated to the fusion protein.
  • the conjugation of the fusion proteins of the disclosure to the cytotoxic agent or chemotherapeutic agent is through a linker selected from the group consisting of a disulfide group, a thioether group, an acid labile group, a photolabile group, a peptidase labile group, and an esterase labile group.
  • the fusion proteins of the disclosure are conjugated to cytotoxic and/or cytostatic agents.
  • the cytotoxic and/or cytostatic agent is conjugated to a sdAb or functional variant thereof of the fusion protein. In some aspects of these embodiments, the cytotoxic and/or cytostatic agent is conjugated to a sdAb or functional variant thereof of the fusion protein. In some aspects of these embodiments, the cytotoxic and/or cytostatic agent is conjugated to a sdAb or functional variant thereof of the fusion protein.
  • the cytotoxic and/or cytostatic agent is conjugated to a CD protein or functional variant thereof of the fusion protein.
  • the fusion protein is conjugated (chemically or genetically) or coupled to a cytokine, a superantigen, and/or a toxin.
  • the pharmacokinetics of the fusion protein can be improved by chemical modification, such as the addition of poly(alkylene) glycol such as poly( ethylene) glycol (“PEGylation”), POLY PEG, PASylation, or by incorporation in a liposome.
  • the fusion protein (e.g., the sdAb or functional variant thereof) comprises one or more additional amino acid residues that allow for pegylation and/or facilitate pegylation (e.g., an additional cysteine residue for easy attachment of a PEG-group).
  • the half-life of the fusion protein is increased by attaching polysialic acid (PSA), hydro xyethyl starch (HES), an albumin-binding ligands or a carbohydrate shield to the fusion protein; by genetic fusion to a protein that binds serum proteins, such as albumin, IgG, FcRn, and/or transferrin; by genetic fusion to albumin or a domain of albumin, or to an albumin-binding protein; or by incorporation of the fusion protein into a nanocarrier, slow release formulation, or medical device.
  • PSA polysialic acid
  • HES hydro xyethyl starch
  • an albumin-binding ligands or a carbohydrate shield to the fusion protein
  • genetic fusion to a protein that binds serum proteins such as albumin, IgG, FcRn, and/or transferrin
  • albumin or a domain of albumin such as albumin, IgG, FcRn,
  • the fusion protein can be modified by glycosylation, acetylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, and/or proteolytic cleavage. These modifications may be carried out by known techniques, including, but not limited to, specific chemical cleavage, acetylation, formylation, and others known in the art. Additionally, the fusion protein may comprise one or more non-classical amino acids.
  • the fusion protein can comprise a detectable label.
  • Suitable detectable labels and methods for labeling a protein are well known in the art.
  • Suitable detectable labels include, for example, a radioisotope (e.g., Indium-111, Technetium-99m or Iodine-l3l), positron-emitting labels (e.g., Fluorine-l9), paramagnetic ions (e.g., Gadolinium (III), Manganese (II)), an epitope label (tag), an affinity label (e.g., biotin, avidin), a spin label, an enzyme, a fluorescent group, or a chemiluminescent group.
  • a radioisotope e.g., Indium-111, Technetium-99m or Iodine-l3l
  • positron-emitting labels e.g., Fluorine-l9
  • paramagnetic ions e.g., Gadolinium (III), Manganese (II)
  • an epitope label tag
  • an affinity label e.g., biotin, avidin
  • spin label
  • nucleic acids including nucleotide sequences that encode the sdAbs, linkers, CD proteins, functional variants of sdAb and/or CD proteins, fusion proteins, or functional equivalents of any of the foregoing as described herein, are used in recombinant DNA molecules that direct the expression of the fusion proteins of the disclosure in appropriate host cells, such as bacterial cells.
  • nucleic acid molecule or“polynucleotide” is intended to include DNA molecules (e.g., cDNA or genomic DNA) and RNA molecules (e.g., mRNA) and analogs of the DNA or RNA generated using nucleotide analogs.
  • the nucleic acid molecule can be single- stranded or double- stranded.
  • the present disclosure pertains to polynucleotides that encode a cytosine deaminase or a mutant cytosine deaminase polypeptide or biologically active portions thereof; polynucleotides that encode a sdAb or biologically active variants thereof; polynucleotides that encode one or more linkers of the disclosure; and polynucleotides that encode a fusion protein of the disclosure.
  • the polynucleotide encoding a CD or functional variant thereof is a codon-optimized polynucleotide.
  • the CD polynucleotide or codon-optimized polynucleotide comprises recombinant, engineered, or isolated forms of naturally occurring nucleic acids isolated from an organism, e.g., a bacterial or yeast strain.
  • Exemplary CD polynucleotides include those that encode a polypeptide set forth in SEQ ID NOs: 21, 22, 186, or 187. The nucleic acids used in the Examples of this disclosure are within the scope of the embodiments.
  • CD or sdAb polynucleotides are produced by diversifying, e.g., recombining and/or mutating one or more naturally occurring, isolated, or recombinant CD or sdAb polynucleotide sequences.
  • CD or sdAb polynucleotides encoding CD or sdAb polypeptides (e.g., a functional variant of CD or sdAb) with superior functional attributes, e.g., increased catalytic function, increased stability, or higher expression level, than an unmodified CD or sdAb polynucleotide used as a substrate or parent in the diversification process.
  • superior functional attributes e.g., increased catalytic function, increased stability, or higher expression level
  • an unmodified CD or sdAb polynucleotide used as a substrate or parent in the diversification process Due to the degeneracy of the genetic code, various nucleic acid sequences which encode substantially the same or a functionally equivalent amino acid sequence can be used to clone and/or express the fusion proteins of the disclosure.
  • polynucleotides of the disclosure have a variety of uses in, for example, recombinant production (i.e., expression) of the fusion proteins of the disclosure and as substrates for further diversity generation, e.g., recombination reactions or mutation reactions to produce new and/or improved variants, and the like.
  • polynucleotide encode a polypeptide with substantial CD activity, or even variant CD activity, or sdAb activity (e.g., target binding).
  • CD polynucleotides that do not encode active enzymes can be valuable sources of parental polynucleotides for use in diversification procedures to arrive at CD polynucleotide variants, or non-CD polynucleotides, with desirable functional properties (e.g., high kcat or kcat/Km, low Km, high stability towards heat or other environmental factors, high transcription or translation rates, resistance to proteolytic cleavage, increased antigen binding, increased antigen specificity, decreased immunogenicity).
  • the polynucleotide encoding a sdAb or functional variant thereof is a codon-optimized polynucleotide.
  • the sdAb polynucleotide or sdAb codon-optimized polynucleotide comprises recombinant, engineered, or isolated forms of naturally occurring nucleic acids isolated from an organism, e.g., dromedaries, camels, llamas, alpacas or sharks.
  • Exemplary polynucleotides that encode a fusion protein of the disclosure include those set forth in SEQ ID NOs: 8, 10, 12, 14, 16, 18, 20, and 195- 198.
  • the term“transformation” means the introduction of a foreign (i.e., extrinsic or extracellular) gene, DNA, or RNA sequence to a host cell, so that the host cell will express the introduced gene or sequence to produce a desired substance, typically a protein or enzyme coded by the introduced gene or sequence.
  • the introduced gene or sequence may include regulatory or control sequences, such as start, stop, promoter, signal, secretion, or other sequences used by the genetic machinery of the cell.
  • a host cell that receives and expresses introduced DNA or RNA has been“transformed” and is a
  • transformant or a“clone.”
  • the DNA or RNA introduced to a host cell can come from any source, including cells of the same genus or species as the host cell, or cells of a different genus or species, or by gene synthesis.
  • the term“codon-optimized sequences” generally refers to nucleotide sequences that have been optimized for a particular host species by replacing any codons having a usage frequency of less than about 20%.
  • Nucleotide sequences that have been optimized for expression in a given host species by, for example, elimination of spurious polyadenylation sequences, elimination of exon/intron splicing signals, elimination of transposon-like repeats, and/or optimization of GC content in addition to codon optimization are referred to herein as“expression enhanced sequences.”
  • the disclosure further provides a vector comprising one or more nucleic acid sequences encoding the disclosed CD proteins or functional variants thereof, sdAbs or functional variants thereof, linkers, and/or fusion proteins.
  • the vector can be, for example, a plasmid, episome, cosmid, viral vector (e.g., retroviral or adenoviral), or phage.
  • Suitable vectors and methods of vector preparation are well known in the art (see, e.g., Sambrook et a , Molecular Cloning, a Laboratory Manual, 4th edition, Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (2012), and Ausubel et ak, Current Protocols in Molecular Biology, Greene Publishing Associates and John Wiley & Sons, New York, N.Y. (1994, and updated chapters available online)).
  • a vector comprising one or more nucleic acids encoding one or more amino acid sequences disclosed herein can be introduced into a host cell that is capable of expressing the polypeptides/proteins encoded thereby, including any suitable prokaryotic or eukaryotic cell.
  • a cell comprising a disclosed vector.
  • Preferred host cells are those that can be easily and reliably grown, have reasonably fast growth rates, have well characterized expression systems, and can be transformed or transfected easily and efficiently.
  • suitable prokaryotic host cells include, but are not limited to, cells from the genera Bacillus (such as Bacillus subtilis and Bacillus brevis), Escherichia (such as E.
  • Suitable prokaryotic host cells include the various strains of Escherichia coli (e.g., K12, HB101 (ATCC No. 33694), DH5, DH10, MC1061 (ATCC No. 53338), and CC102).
  • the host cell is TunerTM (Novagen), AD494 (Novagen), HMS174 (Novagen), NovaBlue (Novagen), BLR (Novagen), C41 (Lucigen), C43 (Lucigen), Lemo2l (NEB), NiCo2l (NEB), BL21, BL2l(DE3), or T7 Express (NEB).
  • the host cell is an E. coli strain that provides a cytoplasmic environment for disulfide bond formation.
  • the cytoplasmic environment is achieved by optimizing the thioredoxin and/or glutathione pathway, and/or by expressing cytosolic disulfide bond isomerase.
  • the host cell is an E. coli strain that constitutively expresses a chromosomal copy of a cytosolic disulfide bond isomerase (e.g., DsbC).
  • the prokaryotic host cells are SHuffle® Express (NEB# C3028) cells (New England Biolabs).
  • the prokaryotic host cells are SHuffle® T7 (NEB #C3026) or SHuffle® Express T7 LysY (NEB# C3030) cells.
  • SHuffle® has deletions of the genes for glutaredoxin reductase and thioredoxin reductase (Agor AtrxB), which allow disulfide bonds to form in the cytoplasm. This combination of mutations is normally lethal, but the lethality is suppressed by a mutation in the gene encoding peroxiredoxin enzyme (ahpC*).
  • SHuffle® expresses a version of the periplasmic disulfide bond isomerase DsbC that lacks its signal sequence, retaining DsbC in the cytoplasm. This enzyme has been shown to act on proteins with multiple disulfide bonds to correct mis-oxidized bonds and promote proper folding. Any other cell line with these properties (e.g., providing a cytoplasmic environment for disulfide bond formation) can be used to prepare the compounds of the disclosure.
  • the prokaryotic host cells are OrigamiTM or Rosetta-gamiTM.
  • yeast eukaryotic expression system examples include, but are not limited to, genera Saccharomyces, Pichia, Kluyveromyces, Hansenula, and Yarrowia.
  • Suitable insect host cells are described in, for example, Kitts et a ,
  • Exemplary insect host cells include Sf-9 and HI5 (Invitrogen, Carlsbad, Calif.).
  • in vitro protein expression examples include, but are not limited to,
  • E. coli lysates E. coli lysates, rabbit reticulocyte lysates (RRL), wheat germ extracts, and insect cell lysates (such as SF9 or SF21 lysates).
  • Cell-free expression system is the production of recombinant proteins in which the protein synthesis occurs in cell lysates rather than within cultured cells.
  • a cell-free expression system can provide several advantages and features that complement traditional in vivo methods, such as faster production speed, because it does not require gene transfection, cell culture, or extensive protein purification.
  • the fusion proteins of the disclosure can be administered alone or in combination with other drugs (e.g., as an adjuvant).
  • drugs e.g., as an adjuvant
  • numerous chemotherapeutics, especially antineoplastic drugs, are available for combination with the fusion proteins of the disclosure.
  • Most chemotherapeutic drugs can be divided into alkylating agents, antimetabolites, anthracyclines, plant alkaloids, topoisomerase inhibitors, antibodies, and other anti-tumor agents.
  • adjunctive or combined administration (co
  • administration includes simultaneous administration of a fusion protein and another drug in the same or different dosage form, or separate administration of fusion protein and another drug (e.g., sequential administration).
  • the fusion proteins of the disclosure are co administered with an antineoplastic drug that damages DNA or interferes with DNA repair.
  • the fusion proteins of the disclosure and an antineoplastic drug that damages DNA or interferes with DNA repair.
  • antineoplastic drug act synergistically.
  • the fusion proteins of the disclosure increase a cell’s sensitivity to the antineoplastic drug, for example, by at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%.
  • Non-limiting examples of antineoplastic drugs that damage DNA or inhibit DNA repair include carboplatin, carmustine, chlorambucil, cisplatin, cyclophosphamide, dacarbazine, daunorubicin, doxorubicin, epirubicin, idarubicin, ifosfamide, lomustine, mechlorethamine, mitoxantrone, oxaliplatin, procarbazine, temozolomide, and valrubicin.
  • the antineoplastic drug is temozolomide, which is a DNA damaging alkylating agent commonly used against glioblastomas.
  • the antineoplastic drug is a PARP inhibitor (e.g., KU0058948, ABT-888 (veliparib), olaparib, KU-59436, AZD-2281, AG-014699, BSI-201, BGP-15, INO-1001, ONO- 2231), which inhibits a step in base excision repair of DNA damage.
  • the antineoplastic drug is a histone deacetylase inhibitor (e.g., Vorinostat; Romidepsin; Chidamide; Panobinostat; Valproic acid; Belinostat;
  • Mocetinostat Abexinostat; Entinostat; SB939 (pracinostat); Resminostat; Givinostat; Quisinostat; thioureidobutyronitrile (KevetrinTM); CUDC-10; CHR-2845 (tefinostat); CHR-3996; 4SC-202; CG200745; ACY-1215 (rocilinostat); ME-344; sulforaphane), which suppresses DNA repair at the transcriptional level and disrupts chromatin structure.
  • the antineoplastic drug is a proteasome inhibitor (e.g., Bortezomib; Carfilzomib; Epoxomicin; Ixazomib; Salinosporamide A), which suppresses DNA repair by disrupting ubiquitin metabolism in the cell.
  • Ubiquitin is a signaling molecule that regulates DNA repair.
  • antineoplastic drug is a kinase inhibitor (e.g., an ATM inhibitor (CP466722 or KU- 55933); a CHK 1 inhibitor (XL-844, UCN-01, AZD7762 or PF00477736), or a CHK 2 inhibitor (XL-844, AZD7762, or PF00477736)), which suppresses DNA repair by altering DNA damage response signaling pathways.
  • a kinase inhibitor e.g., an ATM inhibitor (CP466722 or KU- 55933); a CHK 1 inhibitor (XL-844, UCN-01, AZD7762 or PF00477736), or a CHK 2 inhibitor (XL-844, AZD7762, or PF00477736)
  • antineoplastic drugs that can be combined with the fusion proteins of the disclosure include, but are not limited to, alkylating agents (such as temozolomide, cisplatin, carboplatin, oxaliplatin, mechlorethamine, cyclophosphamide, chlorambucil, dacarbazine, lomustine, carmustine, procarbazine, chlorambucil and ifosfamide), antimetabolites (such as gemcitabine, methotrexate, cytosine arabinoside, fludarabine, and floxuridine), antimitotics, vinca alkaloids such as vincristine, vinblastine, vinorelbine, and vindesine), anthracyc lines (including doxorubicin, daunorubicin, valrubicin, idarubicin, and epirubicin, as well as actinomycins such as actinomycin D), cytotoxic antibiotics (including mitomycin
  • Examples of other chemotherapeutic agents that may be administered in combination with fusion proteins of the disclosure include alkylating agents such as thiotepa and cyclophosphamide; alkyl sulfonates such as busulfan, improsulfan, and piposulfan; aziridines such as benzodopa, carboquone, meturedopa, and uredopa; ethylenimines and methylamelamines including altretamine, triethylenemelamine, triethylenephosphoramide, triethylenethiophosphoramide and trimethylolomelamine; acetogenins (e.g., bullatacin and bullatacinone); delta-9-tetrahydrocannabinol (dronabinol); beta-lapachone; lapachol; colchicines; betulinic acid; a camptothecin (including the synthetic analogue topotecan (CPT-ll (irinotecan),
  • alkylating agents
  • nitrogen mustards such as chlorambucil, chlomaphazine, cholophosphamide, estramustine, ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, novembichin, phenesterine, prednimustine, trofosfamide, and uracil mustard;
  • nitrosureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, and ranimnustine; antibiotics such as the enediyne antibiotics (e.g., calicheamicin, especially calicheamicin gammall, and calicheamicin omegall (see, e.g., Nicolaou et ah, Angew. Chem Intl. Ed. Engl., 33: 183-186 (1994)); dynemicin, including dynamics A; an esperamicin; neocarzinostatin chromophore and related
  • chromoprotein enediyne antibiotic chromophores aclacinomysins; actinomycin; authramycin; azaserine; bleomycins; cactinomycin; carabicin; carminomycin;
  • cyanomorpholino-doxorubicin 2-pyrrolino-doxombicin, doxorubicin HC1 liposome injection and deoxydoxorubicin); epirubicin; esorubicin; idarubicin; marcellomycin; mitomycins such as mitomycin C, mycophenolic acid, nogalamycin, olivomycins, peplomycin, potfiromycin, puromycin, guelamycin, rodorubicin, streptonigrin, streptozocin, tubercidin, ubenimex, zinostatin, and zorubicin; anti-metabolites such as methotrexate, gemcitabine, tegafur, capecitabine, an epothilone, and 5-fluorouracil (5- FU); folic acid analogues such as denopterin, methotrexate, pteropterin, and trimetrexate; purine analogs such as fludarabine, 6-mercaptopurine,
  • mitoguazone mitoxantrone; mopidanmol; nitraerine; pentostatin; phenamet;
  • trichothecenes e.g., T-2 toxin, verracurin A, roridin A, and anguidine
  • urethan vindesine; dacarbazine; mannomustine; mitobronitol; mitolactol; pipobroman;
  • therapeutic agents that may be used in combination with the fusion proteins of the disclosure include bisphosphonates such as clodronate, NE-58095, zoledronio acid/zoledronate, alendronate, pamidronate, tiludronate, or risedronate; as well as troxacitabine (a l,3-dioxolane nucleoside cytosine analog), anti-sense
  • bisphosphonates such as clodronate, NE-58095, zoledronio acid/zoledronate, alendronate, pamidronate, tiludronate, or risedronate
  • troxacitabine a l,3-dioxolane nucleoside cytosine analog
  • oligonucleotides particularly those that inhibit expression or genes in signaling pathways implicated in aberrant cell proliferation, such as, for example, PKC-alpha, Raf, H-Ras, and epidermal growth factor receptor (EGFR); vaccines such as Stimuvax vaccine, Theratope vaccine and gene therapy vaccines, for example, Allovectin vaccine, Leavectin vaccine, and Vaxid vaccine; topoisomerase 1 inhibitor; an anti estrogen such as fulvestrant; a Kit inhibitor such as imatinib or EXEL-0862 (a tyrosine kinase inhibitor); EGFR inhibitor such as erlotinib or cetuximab; an anti- VEGF inhibitor such as bevacizumab; arinotecan; rmRH; lapatinib and lapatinib ditosylate (an ErbB-2 and EGFR dual tyrosine kinase small-molecule inhibitor also known as GW572016); 17AAG (geld
  • the fusion proteins or pharmaceutical compositions disclosed herein are co- administrated with 5-fluorouracil (5-FU).
  • the fusion proteins or pharmaceutical compositions thereof are co -administered with a 5-FU containing regimen for example: FOLFUHD (5-FU and leucovorin, sLV5FU2 (5-FU and leucovorin), IFL (irinotecan, leucovorin, and 5-FU), FLOX (5-FU, leucovorin, and oxaliplatin), mFOLFOX6 (oxaliplatin, leucovorin, and 5-FU), FOLFOX4 (oxaliplatin, leucovorin, and 5-FU), FOLFOX7 (oxaliplatin, leucovorin and 5-FU), FOLFIRI (irinotecan, leucovorin, and 5-FU), FOLFOXIRI (irinotecan, oxaliplatin, leucovorin, leucovorin, leucovorin
  • the fusion proteins or pharmaceutical compositions thereof are co-administered with a 5-FC containing regimen.
  • the 5-FU component of any of the aforementioned 5-FU containing regimens is replaced with 5-FC (e.g., 5-FC and leucovorin; 5-FC, leucovorin, and irinotecan; 5-FC, leucovorin, and oxaliplatin; 5-FU, leucovorin, irinotecan, and oxaliplatin; 5-FU, leucovorin calcium, irinotecan hydrochloride, and oxaliplatin; 5-FC, cyclophosphamide, and methotrexate).
  • fusion proteins or pharmaceutical compositions of the disclosure can be combined with or co-administered with one or more substances that potentiate the cytotoxic effect of the 5-FU.
  • substances that potentiate the cytotoxic effect of 5-FU include, but are not limited to, drugs that inhibit enzymes of the de novo biosynthesis of the pyrimidines; and drugs, such as Leucovorin (Waxman et al., 1982, Eur. J. Cancer Clin. Oncol.
  • the substances that potentiate the cytotoxic effect of 5-FU inhibit the degradation of 5-FU.
  • the substance is Gimeracil.
  • the substances that potentiate the cytotoxic effect of 5-FU decrease the side effect(s) of 5- FU.
  • the substance is Oteracil potassium.
  • the substances that potentiate the cytotoxic effect of 5-FU inhibit the metabolism of 5-FU by inhibiting dihydropyrimidine dehydrogenase.
  • the substance is uracil.
  • Delivery of the fusion proteins or pharmaceutical compositions of the disclosure can be conducted in different ways, including oral, subcutaneous, intravenous, intraperitoneal, or intratumoral administration.
  • Other administration and delivery routes include intra-articular, intra-arterial, intramuscular, parenteral, subcutaneous, intra-pleural, topical, dermal, intradermal, transdermal, parenteral, e.g.
  • transmucosal intra-cranial, intra-spinal, mucosal, respiratory, intranasal, via intubation, intrapulmonary, intrapulmonary instillation, buccal, sublingual, intravascular, intrathecal, intracavity, iontophoretic, intraocular, ophthalmic, intraglandular, intraorgan, and intralymphatic.
  • each delivery/administration pathway has different demands for a fusion protein formulation according to the disclosure, and the formulations can be prepared routinely by one of ordinary skill in the art.
  • the sdAb-CD fusion protein requires resistance to extreme conditions (i.e., proteases and/or acidic pH).
  • the fusion proteins can be made resistant to proteases by adaptation of the sequence or by the introduction of an additional disulfide bond in order to improve resistance to pepsin and chymotrypsin, as is well known in the art.
  • stability in serum can be important. Most sdAbs combined with effector domains or nanoparticles have been described as very stable in serum.
  • the therapeutic use or the treatment method comprises an additional step in which pharmaceutically acceptable quantities of a prodrug, such as an analog of cytosine, in particular 5-FC, are administered to the subject or cell.
  • a prodrug such as an analog of cytosine, in particular 5-FC
  • the method includes at least a first loading dose of 5-FC sufficient to obtain a serum concentration of about 1-200 (e.g., 10-100) pg/ml within 1-2 days of administration ⁇
  • the prodrug is administered in accordance with standard practice (e.g., orally, systematically), with the administration taking place subsequent to the administration of a fusion protein disclosed herein.
  • the prodrug is
  • the prodrug is administered orally. In some embodiments, the prodrug is administered in a single dose. In some embodiments, the prodrug is administered in doses that are repeated for a time sufficient to enable the toxic metabolite to be produced within the host organism or cell.
  • the prodrug is a compound that can be converted in vivo to provide a biologically, pharmaceutically, or therapeutically active form of 5-FC.
  • Such photoactivatable compounds can comprise a photosensitive linker that is cleavable upon irradiation with, for example, a UV light (including lights implanted within a tumor site that can be remotely or temporally activated).
  • a cytosine analog is administered instead of 5- FC.
  • Cytosine analogs that can be substrates for cytosine deaminase include halogenated cytosines and the prodrug 5-fluorocytosine (5-FC) (which is activated by CD to 5-fluorouracil (5-FU)).
  • extended release formulations of 5-FC can be used (e.g., Toca FC).
  • compositions comprising one or more of the fusion proteins disclosed herein.
  • the pharmaceutical composition comprises one or more of the fusion proteins disclosed herein and one or more pharmaceutically acceptable excipients.
  • Pharmaceutical compositions comprising a fusion protein of the disclosure and any post-translational modifications thereof and a pharmaceutically acceptable excipient are also within the scope of this disclosure and may be prepared using methods known in the art. Suitable excipients are well known in the art. The choice of excipient will be determined, in part, by the particular site to which the composition may be administered and the particular method used to administer the composition.
  • the composition optionally can be sterile.
  • the composition can be frozen or lyophilized for storage and reconstituted in a suitable sterile carrier prior to use.
  • the compositions can be generated in accordance with conventional techniques described in, e.g., Remington: The Science and Practice of Pharmacy, 22nd Edition, Lippincott Williams & Wilkins,
  • excipient broadly refers to any component other than the active therapeutic ingredient(s).
  • the excipient may be an inert substance, an inactive substance, and/or a not medicinally active substance.
  • the excipient may serve various purposes, e.g. as a carrier, vehicle, diluent, tablet aid, and/or to improve
  • the pharmaceutical compositions of the disclosure are prepared to have certain stabilities (physical and/or chemical stability).
  • the term“physical stability” refers to the tendency of a polypeptide or protein to form biologically inactive and/or insoluble aggregates as a result of exposure to thermo mechanical stress, and/or interaction with destabilizing interfaces and surfaces (such as hydrophobic surfaces).
  • the physical stability of an aqueous protein formulation may be evaluated by means of visual inspection, and/or by turbidity measurements after exposure to mechanical/physical stress (e.g. agitation) at different temperatures for various time periods.
  • the physical stability may be evaluated using a spectroscopic agent or probe of the conformational status of the protein such as e.g., Thioflavin T or“hydrophobic patch” probes.
  • chemical stability refers to chemical (in particular covalent) changes in the polypeptide or protein structure leading to formation of chemical degradation products potentially having a reduced biological potency, and/or increased immunogenic effect as compared to the intact protein.
  • the chemical stability can be evaluated by measuring the amount of chemical degradation products at various time-points after exposure to different environmental conditions, e.g., by SEC-HPLC and/or RP-HPLC.
  • the fusion proteins of the disclosure can be used therapeutically as pharmaceutical formulations.
  • pharmaceutical formulation refers to a preparation that is in such form as to permit the biological activity of the active ingredient to be effective, wherein the formulation does not comprise additional components that are unacceptably toxic to a subject to whom the formulation would be administered.
  • the pharmaceutical formulations are sterile.
  • a pharmaceutical composition or
  • compositions or formulations may be a solution, emulsion, or suspension (for example, incorporated into microparticles, liposomes, or cells).
  • an appropriate amount of a pharmaceutically acceptable salt is used in the composition or formulation to render it isotonic.
  • pharmaceutically acceptable carriers include, but are not limited to, saline, Ringer’s solution, and dextrose solution.
  • the pH of the solution is preferably from about 5 to about 8, and more preferably from about 7 to about 7.5.
  • Pharmaceutical compositions or formulations may include carriers, thickeners, diluents, buffers, preservatives, and/or surface active agents.
  • Suitable carriers include sustained release preparations, such as semi-permeable matrices of solid hydrophobic polymers containing the fusion protein of the disclosure, which matrices are in the form of shaped particles, e.g., films, liposomes, or microparticles. It will be apparent to those persons skilled in the art that certain carriers may be more preferable depending upon, for instance, the route of administration and concentration of the composition being administered.
  • compositions or formulations may also include one or more additional active ingredients such as cytotoxic agents, cytostatic agents, chemotherapeutic agents, antimicrobial agents, anti-inflammatory agents, and anesthetics.
  • additional active ingredients such as cytotoxic agents, cytostatic agents, chemotherapeutic agents, antimicrobial agents, anti-inflammatory agents, and anesthetics.
  • surfactant might be added as a wetting agent.
  • Surfactants may include anionic detergents such as sodium lauryl sulfate, dioctyl sodium
  • Nonionic detergents that could be used in the formulation as surfactants include, but are not limited to, lauromacrogol 400; polyoxyl 40 stearate; polyoxyethylene hydrogenated castor oil 10, 50, or 60; glycerol monostearate; polysorbate 20, 40, 60, 65, or 80; sucrose fatty acid ester; methyl cellulose; and carboxymethyl cellulose. These surfactants could be present in the pharmaceutical composition or formulation of the fusion protein either alone or as a mixture in different ratios.
  • Additives that may enhance uptake of peptides may be included in a pharmaceutical composition or formulation of the disclosure.
  • the composition or formulation includes one or more of the fatty acids oleic acid, linoleic acid, and linolenic acid.
  • the fusion proteins of the disclosure can be used in, for example, the treatment of proliferative diseases (cancers/tumors, restenosis, glaucoma, scarring).
  • the disclosure pertains to a method comprising administering a fusion protein or pharmaceutical composition or formulation thereof to a subject having a cancer or any disease disclosed herein, whereupon the disease is treated in the subject.
  • the fusion proteins, pharmaceutical compositions, and/or pharmaceutical formulations described herein can be used in diagnostic or research applications.
  • the fusion proteins of the disclosure, or pharmaceutical composition or formulations thereof can be used to treat any cancer known in the art such as colon cancer, esophagus cancer, stomach cancer, pancreatic cancer, breast cancer, basal cell carcinoma, Bowen’ s disease, and cervical cancer.
  • the compounds of the disclosure can be used to treat ocular surface squamous neoplasia.
  • the disclosed fusion proteins, pharmaceutical compositions, and/or pharmaceutical formulations can be used to treat melanoma, renal cell carcinoma, lung cancer, bladder cancer, breast cancer, cervical cancer, colon cancer, gall bladder cancer, laryngeal cancer, liver cancer, thyroid cancer, stomach cancer, salivary gland cancer, prostate cancer, pancreatic cancer, cholangiocarcinoma, esophagus cancer, bone cancer, endometrial cancer, ovarian cancer, soft tissue sarcoma, or Merkel cell carcinoma.
  • the disclosed fusion proteins, pharmaceutical compositions, and/or pharmaceutical formulations can be used to treat a solid tumor.
  • the solid tumor is colon cancer, colorectal cancer, pancreatic cancer, or head and neck cancer.
  • the disclosed fusion proteins, pharmaceutical compositions, and/or pharmaceutical formulations can be used to treat actinic keratosis. In some embodiments, the disclosed fusion proteins, pharmaceutical compositions, and/or pharmaceutical formulations can be used as an adjunctive therapy in ocular and/or periorbital surgeries. In some embodiments, the disclosed fusion proteins, pharmaceutical compositions, and/or pharmaceutical formulations can be used in the treatment of hypertrophic (HTSs) and/or keloid scars.
  • HTSs hypertrophic
  • treatment refers to the medical management of a patient with the intent to cure, ameliorate, or stabilize a disease.
  • This term includes active treatment, that is, treatment directed specifically toward the improvement of a disease, pathological condition, or disorder, and also includes causal treatment, that is, treatment directed toward removal of the cause of the associated disease, pathological condition, or disorder.
  • this term includes palliative treatment, that is, treatment designed for the relief of symptoms rather than the curing of the disease, pathological condition, or disorder; preventative treatment, that is, treatment directed to minimizing or partially or completely inhibiting the development of the associated disease, pathological condition, or disorder; and /or supportive treatment, that is, treatment employed to supplement another specific therapy directed toward the improvement of the associated disease, pathological condition, or disorder.
  • the term“therapeutically effective” means that the amount of the protein, composition, or formulation used is of sufficient quantity to ameliorate one or more causes or symptoms of a disease or disorder. Such amelioration only requires a reduction or alteration, not necessarily elimination.
  • a therapeutically effective amount of a protein, composition, or formulation for treating cancer is preferably an amount sufficient to cause tumor regression or to sensitize a tumor to radiation or chemotherapy.
  • the amount of the disclosed fusion proteins, pharmaceutical compositions, and/or pharmaceutical formulations that is required for use in treatment will vary not only with the particular sdAb (or functional variant thereof) and fusion protein selected but also with the route of administration, the nature of the condition being treated, and the age and condition of the patient, among other factors, and will be ultimately at the discretion of the attendant physician or clinician.
  • the dosage of the disclosed fusion proteins, pharmaceutical compositions, and/or pharmaceutical formulations may vary depending on the target cell, tumor, tissue, graft, or organ.
  • the fusion proteins of the disclosure may generally be administered in an amount between 1 gram and 0.01 micro gram per kg body weight per day, preferably between 0.1 gram and 0.1 microgram per kg body weight per day, such as about 1, 10, 100, or 1000 micrograms per kg body weight per day, either continuously (e.g., by infusion), as a single daily dose or as multiple divided doses during the day.
  • the fusion proteins of the disclosure are administered in an amount from about 10 mg/kg to about 60 mg/kg.
  • the fusion proteins of the disclosure are administered in an amount from about 10 mg/kg/day to about 60 mg/kg/day.
  • Other suitable doses for the fusion proteins of the disclosure can be, for example, in the range of 1 pg/kg to 60 mg/kg of animal or human body weight;
  • the daily parenteral dose can be about 0.00001 pg/kg to about 20 or about 40 mg/kg of total body weight (e.g., about 0.001 pg/kg, about 0.1 pg/kg, about 1 pg/kg, about 5 pg/kg, about 10 pg/kg, about 100 pg/kg, about 500 pg/kg, about 1 mg/kg, about 5 mg/kg, about 10 mg/kg, or a range defined by any two of the foregoing values), preferably from about 0.1 pg/kg to about 10 mg/kg of total body weight (e.g., about 0.5 pg/kg, about 1 pg/kg, about 50 pg/kg, about 150 pg/kg, about 300 pg/kg, about 750 pg/kg, about 1.5 mg/kg, about 5 mg/kg, or a range defined by any two of the foregoing values), more preferably from
  • Therapeutic or prophylactic efficacy can be monitored by periodic assessment of treated patients. For repeated administrations over several days or longer, depending on the condition, the treatment can be repeated until a desired suppression of disease symptoms occurs.
  • other dosage regimens may be useful and are within the scope of the disclosure.
  • the desired dosage can be delivered by a single bolus administration of the composition, by multiple bolus administrations of the composition, or by continuous infusion administration of the compositions of the disclosure.
  • Other methods of administration that can be used with the fusion proteins disclosed herein are exemplified elsewhere in this document.
  • FIG. 1 A The design of a Rituxan-CD-CD fusion protein is shown in FIG. 1 A.
  • the nucleic acids sequence of Rituxan heavy chain, Rituxan light chain and yeast cytosine deaminase can be synthesized by gene synthesis.
  • the coding fragment containing SP-RituxanHC-CD-linker-CD (SEQ ID NO: 89) and SP-RituxanLC (SEQ ID NO: 90) were generated by overlapping PCR.
  • the fragment SP-RituxanHC-CD- linker-CD and SP-RituxanLC were than cloned into pCHOl.O vector via
  • FIG. 1B The design of a Herceptin-CD fusion protein is shown in FIG. 1B.
  • the nucleic acids sequence of Herceptin variable region and yeast cytosine deaminase can be synthesized by gene synthesis.
  • the coding fragment containing SP-HerceptinHC- CD (SEQ ID NO: 91) and SP-HerceptinLC (SEQ ID NO: 92) were generated by overlapping PCR.
  • the fragment SP-HerceptinHC-CD and SP-HerceptinLC were than cloned into pCHOl.O vector via AvrII/BstZ 171 site and EcoRV/PacI site respectively.
  • FreeStyle MaxTM reagent according to the transfection protocol of FreeStyle MaxTM.
  • Supernatants were harvested at 72 hours after transfection. The supernatants were then: (1) quantified by ELISA to determine protein titer, (2) purified by Protein A and expression pattern checked by non-reducing PAGE, and (3) concentrated for CD activity analysis.
  • the coding sequence for each fusion protein comprises two main components, one encoding the antigen-recognition fragment (targeting domain), such as sdAb, antigen binding fragment, or endostatin; and one encoding the yeast cytosine deaminase fragment.
  • a coding sequence encoding a linker peptide sequence connected the main components, such that, when expressed, the linker does not interfere with the function of either the targeting domain protein component or the CD component.
  • the expression plasmid is simplified in the schematic shown in FIG. 2A.
  • the nucleic acid sequences of sdAb and yeast cytosine deaminase can be synthesized by gene synthesis.
  • the coding fragment of the sdAb-CD fusion proteins was obtained by overlapping PCR using specific primers.
  • the linker peptide sequence between the sdAb and CD was (GGGGS)3 (SEQ ID NO: 188).
  • the fragments were cloned into a pET28a vector (Novagen) via Xbal and Xhol sites (FIG. 2A). Fusion protein variants with CD mutation(s) or VHH mutation(s) were generated by overlapping PCR.
  • the nucleic acid sequences of yeast cytosine deaminase were synthesized by gene synthesis.
  • the coding fragment of antigen-binding fragment-CD (SEQ ID NOs: 81-84) was obtained by extension PCR using specific primers.
  • the linker peptide sequence between the antigen-binding fragment and CD was
  • the nucleic acid sequences of endostatin and yeast cytosine deaminase were synthesized by gene synthesis.
  • the coding fragment of endostatin-CD fusion proteins (SEQ ID NO: 85) was obtained by overlapping PCR using specific primers.
  • the linker peptide sequence placed in between antigen binding fragment and CD was (GGGGS)3 (SEQ ID NO: 188). The fragments were than cloned into pET28a vector
  • T7 express or T7 express competent E. coli cells (New England Biolabs) by a standard transformation procedure.
  • the recombinant proteins were expressed and purified in about 300 mL production scale.
  • the refreshed transformants was inoculated at 1 :100 dilution in the selection medium at 30°C (SHuffle® T7 Express cells) or 37°C (T7 Express cells) until OD600 reached 0.4 - 0.8 (Io). IPTG (Uni-region) at 0.4 mM was added to induce protein expression.
  • T7 Express cells the induced culture was incubated at 37°C for 5 hours.
  • SHuffle® T7 Express cells after induction temperature for production was 25 °C or 30°C, the temperature for production was 25° The induction temperature was 30°C.
  • the culture was harvested and resuspended in PBS for cell lysis by sonication.
  • the soluble and insoluble fractions were collected from cell lysate separately.
  • the soluble fraction of the cell lysate was firstly incubated with Ni Sepharose beads (GE Healthcare) at room temperature for 1 hour. After incubation, Ni beads (GE) was washed with 20 mM, 40 mM and 80 mM imidazole gradient (Wl, W2 and W3, respectively).
  • Each fusion protein was eluted with buffer containing 150 mM and 250 mM imidazole (El and E2). The samples from each step were analyzed by SDS-PAGE to assess the expression and purification profile.
  • the purified recombinant proteins were collected and exchanged to PBS with 5% glycerol for SDS-PAGE, SEC-HPLC, CD activity and antigen-binding activity analysis.
  • the expression titer, physiochemical characteristics, CD activity and antigen-binding activity of all recombinant proteins were estimated and are summarized in FIG. 2B.
  • the expression profiles are exemplified in FIG. 2C and FIG. 2D.
  • the SDS-PAGE, SEC-HPLC, CD activity and antigen binding activity analysis of purified sdAb-CD are exemplified in FIGs. 3, 4A, 4B, 5A, 5B, 6A, and 6B.
  • the results show that the sdAb-CD fusion proteins are mostly expressed in soluble form and exhibit acceptable purity profile during SDS-PAGE and SEC-HPLC analysis.
  • the titer of sdAb-CD fusion proteins during small scale production were about or exceed 10 pg/mL, the titer can be further increased to 160- 400 mg/L in large scale production, and may be increased to > 1 g/L after process optimization, which are suitable for industrial production.
  • the antigen-binding activity and CD activity were maintained in all sdAb-CD fusion proteins.
  • endostatin-CD could not be expressed in soluble form, thus is not suitable for industrial production.
  • the antigen-binding fragment-CD fusion proteins though with smaller molecular weight, seemed to be expressed in soluble form. Most of the antigen-binding fragment-CD fusion proteins were aggregated as dimer or multimer form, and the antigen-binding fragments lost their antigen-binding activity when fused with CD.
  • sdAb-CD fusion proteins More than ten sdAb-CD fusion proteins and five targeting antigens were tested, and the data showed that sdAb is a suitable antigen-binding fragment for fusion with CD, with both sdAb and CD retaining their biological activity.
  • Example 5 Stability study of sdAb-CD produced from different E. coli strain
  • the 3VGR19-CD-H fusion proteins expressed from SHuffle® T7 Express and T7 Express Competent E. coli were purified and dialyzed into the following four buffers at 3 mg/mL: (1) PBS (2) 1% glycerol in PBS (3) 5% glycerol in PBS (4) 3% mannitol in PBS. The appearances of the purified protein in each buffer were observed after incubation at 37°C for 3 hours, 37°C for 8 hours and 4°C for 1 week, and summarized in Table 1. The number of“+” indicates the turbidity level.“+/-” means that very minor aggregation was observed.
  • the cell pellet was resuspended with a buffer that is composed of 20 mM TrisHCl, 0.5 M NaCl, 20 mM imidazole, and 5% Glycerol, pH 8.0, and homogenized by homogenizer (APV2000) twice at 850-950 bar for less than 10 minutes.
  • the resulting homogenate was clarified by centrifugation at 22000 xg for 60 minutes at 4°C and filtered.
  • the cell lysate was then applied to an FPLC with a Ni Sepharose column followed by an ion-exchange Q-Sepharose column.
  • the cell lysate was loaded onto the Ni Sepharose column with 20 mM TrisHCl, 0.5 M NaCl, 20 mM imidazole, and 5% Glycerol, pH 8.0, and then eluted with a gradient of 0-500 mM imidazole in 20 mM TrisHCl, 0.5 M NaCl, and 5% Glycerol, pH 8.0.
  • the eluent was loaded onto the ion-exchange Q-Sepharose column with 20 mM TrisHCl, 170 mM NaCl, 5% glycerol, pH 8.0, and the flow through was collected as purified product and then washed with 20 mM TrisHCl, 1000 mM NaCl, 5% glycerol, pH 8.0, to remove impurities and aggregates.
  • the purified fusion proteins were analyzed by SDS-PAGE. The results show that all the sdAb-CD fusion proteins showed high purity after purification (FIG. 7A).
  • the cell pellet was resuspended in a buffer that is composed of 20 mM
  • the resulting homogenate was clarified by centrifugation at 22000 xg for 60 minutes at 4°C and filtered.
  • the filtrate was purified by rProteinA affinity column (Repligen) followed by an ion-exchange column anion exchanger Q sepharose (GE).
  • the buffer system for rProteinA affinity column comprising 5% glycerol, 20 mM Tris-HCL and 150 mM
  • the buffer for ion-exchange column chromatography comprised 5% glycerol, 20 mM Tris-HCl and 150 mM NaCl at pH 8.0.
  • the purified product was then filtrated by 5 kDa (pore size) TFF system to concentrate the product (Tangential flow filtration) (Merck Millipore), and the buffer was exchanged by 10 kDa Amicon filter (Merck Millipore). (FIG. 7B).
  • BioSep SEC-s2000 Phenomenex
  • Superdex 200 Increase GE Healthcare 10/300 column resin
  • Samples of the protein produced as above were first diluted to 1 or 2 mg/mL in PBS containing 5% glycerol.
  • the samples were filtered using a 0.2 pm syringe filter (PureTech) and placed in a PP Insert (Thermo) for SEC-HPLC analysis.
  • the mobile phase for BioSep SEC-s2000 was 0.1M sodium phosphate with 0.3 M sodium chloride, pH 7.0.
  • the mobile phase for Superdex 200 Increase was 5% glycerol in PBS.
  • the flow rate for either column was 0.5 mL/min.
  • the column temperature was set at 25 ⁇ 2°C and the auto-sampler temperature was set at 10 ⁇ 2°C. Proteins were detected by absorbance at UV280. The results showed that the purity for anti-VEGFR2 sdAb-CD fusion proteins 3VGR19- CD-H, 4VGR17-CD-H, and 4VGR38-CD-H was about 71%, about 74%, and about 71% respectively (FIG. 4A). The purity for anti-EGFR sdAb-CD fusion proteins VHH122-CD-H and 7D12-CD-H was about 83% and about 87%, respectively (FIG. 4A).
  • the purity was about 88% and about 93%, respectively (FIG. 4A). After optimization of the purification process, the purity may reach about or over 95% (FIG. 4B).
  • sdAb-CD fusion proteins were prepared as above, serial diluents of the fusion protein samples were mixed with 20 mM 5-FC in buffer comprising 0.25% BSA and 0.05% Tween 20, and the mixtures were incubated at 37°C for 90 minutes. The reactions were then stopped with 10% trichloroacetic acid and the mixtures were centrifuged at 4°C for supernatant collection. The presence of 5-FC and 5-FU was detected by absorbance at 290 nm and 255 nm, respectively.
  • VEGFR2 binding assay the coating antibody Human VEGFR2-Fc (Sino Biological) was diluted to 1 pg/ml in coating buffer (100 mM NaHC03 + 32mM Na2HC03). Blocking was performed by incubating with blocking buffer (0.25% BSA, 0.05% Tween-20, 0.05% NaN3, 1 mM EDTA) for 2 hours. The tested fusion protein samples were prepared in blocking buffer and added to wells for binding. Rabbit anti-His-HRP (abeam) was diluted 5000-fold in a buffer comprising 0.25% BSA and 0.05% Tween 20 for detection.
  • coating buffer 100 mM NaHC03 + 32mM Na2HC03
  • Blocking was performed by incubating with blocking buffer (0.25% BSA, 0.05% Tween-20, 0.05% NaN3, 1 mM EDTA) for 2 hours.
  • the tested fusion protein samples were prepared in blocking buffer and added to wells for binding.
  • EGFR binding assay ELISA plates were coated with hEGFR- Fc (Sino Biological) with concentration 1 pg/rriL in coating buffer. Blocking was performed by incubating with blocking buffer (0.25% BSA, 0.05% Tween-20, 0.05% NaN 3 , 1 mM EDTA) for 2 hours. After blocking, the samples were serial diluted in blocking buffer and added to wells for binding 1 hour. Finally, the secondary antibodies (Rabbit anti-HIS-HRP) were diluted in buffer comprising 0.25% BSA and 0.05% Tween 20 for detection.
  • blocking buffer 0.25% BSA, 0.05% Tween-20, 0.05% NaN 3 , 1 mM EDTA
  • the coating antibody for each assay was human ErbB2/Her2-Fc (Aero biosystem), human ErbB3/Her3-Fc (Aero biosystem), and human CEACAM5-Fc (novoprotein), respectively.
  • VGR38-CD-H bind to VEGFR2; VHH122CD-H and 7D12-CD-H bind to EGFR; 5F7-CDoem3-H, 47D5-CDoem3-H, and 2D3-CDoem3-H bind to HER2, NbCEA5- CDoem3-H and AntiCEA-CDoem3-H bind to CEACAM5; and BCD090-M2-
  • CDoem3-H binds to HER3 (FIG. 6 A and FIG. 6B).
  • Example 11 Cell-based cytotoxic assay for sdAb-CD fusion proteins
  • Protocol A [00250] Protocol A:
  • A431 human epidermoid carcinoma EGFR-expressing cancer cell lines.
  • the cells were First seeded at 30,000 cells/well in 96-well plates and incubated at 37°C overnight in growth medium (DMEM (Gibco) plus 10% FBS). After 16-18 hours of incubation, the wells were washed once with PBS. One hundred microliters of fusion protein at 100 pg/ml were added to each well and incubated for 1 hour at 37°C. After washing with PBS to remove excess fusion protein, 100 pl of the 5-FC or 5-FU at indicated concentrations were added to the respective wells for 72 hours incubation.
  • Protocol B [00252]
  • the cytotoxicity of anti-EGFR sdAb-CD fusion proteins of the disclosure combined with 5-FC was tested on A431, Bx-PC3, Cal-27, and FaDu cancer cell lines.
  • a CD protein with a C-terminal His-tag (CDoem3-H) was used as negative protein control (NP).
  • NP negative protein control
  • the cells were re-suspended with 4 mL culture medium containing 2 mM NP or sdAb-CD and incubated in 37°C for 1 hour. Each cell line used the growth medium suggested by ATCC: A431: CRL-1555TM; FaDu: HTB-43TM; Cal 27: CRL-2095TM; BxPC-3:CRL-l687TM.
  • the cells were then washed three times with PBS and re-seeded at 30,000 cells/well in a 96-well plate. 5- FC at the indicated concentrations was added to the wells and incubated at 37°C for 72 hours. After incubation, 10 pl of cell proliferation reagent WST-l were added and the mixtures were incubated at 37°C for 3 hours. Cell survival was measured using an ELISA reader at OD450 and OD690. The results indicate that anti-EGFR sdAb-CD fusion proteins decreased the survival rate for all tested cancer cell lines (FIG. 10A and FIG. 10B).
  • Intravenous administration of 7Dl2-CDoem3-H or 7Dl2-CDoem3 at either 20 mg/kg or 40 mg/kg with intraperitoneal injection of 5-FC at a dose of 500 mg/kg resulted in a significant reduction in the growth of A431 tumors, as shown by the reductions in both tumor volume and tumor weight compared to the vehicle- treated group after tumor cell transplantation (p ⁇ 0.01) (FIG. 11A and FIG. 11B). This confirms that co-administration of 7Dl2-CDoem3-H or 7Dl2-CDoem3 with 5-
  • FC can have an inhibitory effect on A431 cancer cell growth in vivo.
  • T cell epitopes were identified within the 7D12- CDoem3 sequence, epitopes 1-3 located at the framework region of 7D12 sdAb, and epitope 4-6 located at the CD region.
  • Expression plasmids of 43 multi-mutation variants of TC3 were generated by overlapping PCR. These fusion protein variants were generated and the CDase activity, EGFR-binding activity and expression profile thereof were accessed. The results are summarized in FIG. 13A and FIG. 13B.
  • a cohort of 52 donors was selected to best represent the number and frequency of HFA-DR and HFA-DQ allotypes expressed in European/North
  • PBMCs from each donor were resuspended in
  • AIM-V® to 4-6xl0 6 PBMC/mF.
  • the final sample concentration of the tested recombinant protein was 0.3 mM.
  • Cultures were incubated for a total of 8 days. On days 5, 6, 7, and 8, the cells in each well were pulsed with 0.75 pCi [3H]-Thymidine
  • Counts per minute (cpm) for each well were determined by scintillation counting on a 1450 Microbeta Wallac Trilux Liquid Scintillation Counter (Perkin Elmer®, Beaconsfield, UK) in paralux, low background counting.
  • PBMCs from the same cohort of donors were used for the IL-2 ELISpot assay.
  • ELISpot plates (Millipore, Watford, UK) were pre-wetted and coated overnight with IL-2 capture antibody (R&D Systems, Abingdon, UK). The cell density for each donor was adjusted to 4-6 x 10 6 PBMC/ml in AIM-V® culture medium and 100 pL of cells were added to each well. Fifty microliters of samples and controls were added to the appropriate wells. After an 8-day incubation period, ELISpot plates were developed according to the manufacturer’ s instructions (R&D Systems).
  • SI mean of test wells (cpm or spw) / baseline
  • FIG. 14 shows the summary of healthy donor T cell proliferation and IL-2 ELISpot responses. Positive T cell responses for proliferation (SI >1.90, significant p ⁇ 0.05) during the entire time course days 5-8 (“P”), and IL-2 (SI >1.90, significant p ⁇ 0.05) ELISpot (“E”) are indicated. The frequency of positive responses for proliferation and IL-2 ELISpot assays are shown as a percentage at the bottom of the columns. Correlation is expressed as the percentage of proliferation responses also positive in the ELISpot assay.
  • CD activity was assessed by the method described in Example 8.
  • Binding affinity between TC4 related proteins and EGFR-Fc were measured by Surface Plasmon Resonance (SPR). SPR assay was performed by Biacore T100 (GE Healthcare). Anti-human IgG(Fc) antibody at 25 pg/mL was diluted in immobilization buffer (10 mM NaOAc, pH 5.0). Antibody was immobilized on a CM5 chip (Series S Sensor Chip CM5, GE; Cat. No. :29l04988) via standard amine coupling chemistry according to manufacture protocol. The procedure should result in immobilization level of -9000 RU. The mobile phase was PBST and the temperature in the flow cells was maintained at 25 °C.
  • the ligand solution humans EGFR-Fc protein, 2 pg/mL in mobile phase
  • TC4-wt or TC4- mutants which were diluted to 0.74, 2.22, 6.67, 20, and 60 nM in PBST, was injected to systems from low concentration to high concentration.
  • the condition for analyte injection was contact time 120 seconds for each concentration and dissociate samples for 600 seconds at the final step.
  • the analysis was performed with Biacore T100 Evaluation Software.
  • the analytical result of single-cycle kinetics analyte for each sample was fit by two state reaction to determine the KD value.
  • the result criterion was that the maximum response (Rmax) should be in the range of 50-250 RU.

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BR112020013244-6A BR112020013244A2 (pt) 2018-01-04 2019-01-04 proteínas de fusão de anticorpo citosina-desaminase de domínio único
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EP19736000.1A EP3735420A4 (en) 2018-01-04 2019-01-04 SINGLE DOMAIN ANTIBODY CYTOSINE DEAMINASE FUSION PROTEINS
MX2020006822A MX2020006822A (es) 2018-01-04 2019-01-04 Proteinas de fusion de anticuerpo de un solo dominio-citosina desaminasa.
AU2019205128A AU2019205128A1 (en) 2018-01-04 2019-01-04 Single-domain antibody-cytosine deaminase fusion proteins
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IL275691A IL275691A (en) 2018-01-04 2020-06-28 Antibody-fused proteins with a single-site cytosine daminase
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WO2023198007A1 (en) * 2022-04-11 2023-10-19 Bj Bioscience Inc. Anti-nectin-4 antibodies and bispecific antibodies

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EP4135733A4 (en) * 2020-04-17 2024-06-26 University of Cincinnati MODIFIED PROBIOTICS FOR TREATMENT AND IMMUNITY AGAINST VIRUSES
CN118215685A (zh) * 2021-12-27 2024-06-18 山东先声生物制药有限公司 抗gucy2c抗体及其应用
CN116063498A (zh) * 2022-04-27 2023-05-05 博际生物医药科技(杭州)有限公司 单域抗Nectin-4抗体
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WO2022152862A1 (en) * 2021-01-14 2022-07-21 Institut Curie Her2 single domain antibodies variants and cars thereof
US20240317890A1 (en) * 2021-01-14 2024-09-26 Institut Curie Her2 single domain antibodies variants and cars thereof
WO2023198008A1 (en) * 2022-04-11 2023-10-19 Bj Bioscience Inc. Compositions and methods for treating cancer
WO2023198007A1 (en) * 2022-04-11 2023-10-19 Bj Bioscience Inc. Anti-nectin-4 antibodies and bispecific antibodies

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