Humanized tetra-specific octavalent antibody against clostridium difficile toxin A and B
Novel, antibody-based binding agents derived from camelid V H H and human immunoglobulins are described. These binding agents recognize and bind with specificity to Clostridium difficile toxin A and/or toxin B and in some cases exhibit toxin neutralizing activity. These binding agents can be used to treat or prevent primary and recurrent CDI. The binding agents include humanized V H H peptide monomers, linked groups of humanized V H H peptide monomers, humanized V H H peptide monomers joined to antibody Fc domains, and humanized V H H peptide monomers joined to IgG antibodies.
1. A tetra-specific, octameric binding agent comprising, two sets of linked first and second humanized V H H peptide monomers, and two sets of linked third and fourth humanized V H H peptide monomers,
wherein the binding agent comprises two arms, each arm comprising a heavy chain lacking a variable region and a light chain lacking a variable region, and each chain having an amino terminus,
wherein for each arm of the binding agent, one set of linked first and second humanized V H H peptide monomers is joined to the amino terminus of the light chain, and one set of linked third and fourth humanized V H H peptide monomers is joined to the amino terminus of the heavy chain, and wherein the humanized V H H peptide monomers independently have binding specificity for an epitope of Clostridium difficile toxin A (TcdA) or toxin B (TcdB) and are selected from h5D (SEQ ID NO:1), hE3 (SEQ ID NO:2), hAA6 (SEQ ID NO:3) and hAH3 (SEQ ID NO:4), wherein the first, second, third, and fourth humanized V H H peptide monomers have specificity for one or a combination of epitopes and are selected from h5D (SEQ ID NO: 1), hE3 (SEQ ID NO:2), hAA6 (SEQ ID NO:3) and hAH3 (SEQ ID NO:4).
2. The binding agent of claim 1 , each of the first, second, third and fourth humanized V H H peptide monomers has binding specificity for a different epitope.
3. The binding agent of claim 1 , wherein two of the humanized V H H peptide monomers have binding specificity for epitopes of TcdA and two of the humanized V H H peptide monomers have binding specificity for epitopes of TcdB.
4. The binding agent of claim 1 , wherein the humanized V H H peptide monomers independently have binding specificity for an epitope in the glucosyltransferase domain, cysteine protease domain, translocation domain or receptor binding domain of TcdA or TcdB.
5. The binding agent of claim 1 , wherein the light chain of the binding agent comprises the amino acid sequence set forth in SEQ ID NO:8 (AA6/E3 kappa) or a sequence variant having at least 90% sequence identity thereto, and wherein the heavy chain of the binding agent comprises the amino acid sequence set forth in SEQ ID NO:9 (AH3/5D heavy) or a sequence variant having at least 90% sequence identity thereto.
6. The binding agent of claim 5 , wherein variant amino acids of the sequence variant are located in framework regions of the humanized V H H peptide monomer.
7. The binding agent of claim 1 , wherein the two arms comprise constant regions derived from IgG1, IgG2, IgG3 or IgG4.
8. An isolated polynucleotide sequence comprising a nucleotide sequence encoding the light chain arm of the binding agent and the heavy chain arm if the binding agent of claim 1 , or a complementary strand thereof.
9. An expression vector comprising the isolated polynucleotide sequence of claim 8 .
10. An isolated host cell comprising the isolated polynucleotide sequence of claim 8 .
11. A method of producing a binding agent comprising culturing the isolated cell of claim 10 under conditions promoting expression of the binding agent encoded by the expression vector, and recovering the binding agent from the cell culture.
12. A bi-specific or tetra-specific, tetrameric binding agent comprising an IgG antibody and first, second, third and fourth humanized V H H peptide monomers,
wherein the IgG antibody comprises two arms, each arm comprising a heavy chain lacking a variable region and a light chain lacking a variable region, and each chain having an amino terminus,
wherein for a first arm of the antibody, the first humanized V H H peptide monomer is joined to the amino terminus of the light chain, and the second humanized V H H peptide monomer is joined to the amino terminus of the heavy chain,
wherein for a second arm of the antibody, the third humanized V H H peptide monomer is joined to the amino terminus of the light chain, and the fourth humanized V H H peptide monomer is joined to the amino terminus of the heavy chain, and
wherein each of the humanized V H H peptide monomers has binding specificity for an epitope of Clostridium difficile toxin A (TcdA) or toxin B (TcdB) and are selected from h5D (SEQ ID NO:1), hE3 (SEQ ID NO:2), hAA6 (SEQ ID NO:3) and hAH3 (SEQ ID NO:4), wherein the first, second, third, and fourth humanized V H H peptide monomers have specificity for one or a combination of epitopes and are selected from h5D (SEQ ID NO: 1), hE3 (SEQ ID NO:2), hAA6 (SEQ ID NO:3) and hAH3 (SEQ ID NO:4).
13. A tetra-specific, octameric binding agent comprising an antibody Fc domain and two sets of linked first, second, third and fourth humanized V H H peptide monomers,
wherein the antibody Fc domain comprises a first and second arm, each arm comprising hinge, C H 2 and C H 3 regions of an antibody heavy chain, and each arm having an amino terminus,
wherein for each arm of the Fc domain, one set of linked first, second, third and fourth humanized V H H peptide monomers is joined to the amino terminus of the arm, and
wherein the humanized V H H peptide monomers have binding specificity for an epitope of Clostridium difficile toxin A (TcdA) or toxin B (TcdB) and is selected from h5D (SEQ ID NO:1), hE3 (SEQ ID NO:2), hAA6 (SEQ ID NO:3) and hAH3 (SEQ ID NO:4), wherein the first, second, third, and fourth humanized V H H peptide monomers have specificity for one or a combination of epitopes and are selected from h5D (SEQ ID NO: 1), hE3 (SEQ ID NO:2), hAA6 (SEQ ID NO:3) and hAH3 (SEQ ID NO:4).
14. A bi-specific, tetrameric binding agent comprising an antibody Fc domain and two sets of linked first and second humanized V H H peptide monomers,
wherein the antibody Fc domain comprises a first and second arm, each arm comprising hinge, C H 2 and C H 3 regions of an antibody heavy chain, and each arm having an amino terminus,
wherein for each arm of the Fc domain, one set of linked first and second humanized V H H peptide monomers is joined to the amino terminus of the arm, and
wherein the humanized V H H peptide monomers have binding specificity for an epitope of Clostridium difficile toxin A (TcdA) or toxin B (TcdB) and are selected from h5D (SEQ ID NO:1), hE3 (SEQ ID NO:2), hAA6 (SEQ ID NO:3) and hAH3 (SEQ ID NO:4), wherein the first, second, third, and fourth humanized V H H peptide monomers have specificity for one or a combination of epitopes and are selected from h5D (SEQ ID NO: 1), hE3 (SEQ ID NO:2), hAA6 (SEQ ID NO:3) and hAH3 (SEQ ID NO:4).
15. A humanized V H H peptide binding agent comprising at least one humanized V H H peptide monomer, wherein each humanized V H H peptide monomer has binding specificity for a unique epitope of Clostridium difficile toxin A (TcdA) or toxin B (TcdB), wherein the at least one humanized V H H peptide monomers is selected from h5D (SEQ ID NO:1), hE3 (SEQ ID NO:2), hAA6 (SEQ ID NO:3) and hAH3 (SEQ ID NO:4), wherein the first, second, third, and fourth humanized V H H peptide monomers have specificity for one or a combination of epitopes and are selected from h5D (SEQ ID NO: 1), hE3 (SEQ ID NO:2), hAA6 (SEQ ID NO:3) and hAH3 (SEQ ID NO:4).
16. A pharmaceutical formulation comprising a binding agent of claim 1 and a pharmaceutically acceptable carrier or diluent.
17. A method of treating or preventing a disease symptom induced by C. difficile in a subject comprising administering a therapeutically-effective amount of the binding agent of claim 1 to a subject having C. difficile infection or a risk of developing C. difficile infection.
18. A method of neutralizing C. difficile toxin TcdA and/or TcdB in a subject infected by C. difficile comprising administering a therapeutically-effective amount of the binding agent of claim 1 to a subject having C. difficile infection.
19. A method of treating or preventing C. difficile infection in a subject comprising administering a therapeutically-effective amount of the binding agents of claim 1 to a subject having C. difficile infection or a risk of developing C. difficile infection.