V-Like Domain Binding Molecules

Abstract

The present invention relates to binding moieties comprising at least one monomeric V-like domain (VLD) derived from a non-antibody ligand, the at least one monomeric V-like domain being characterised in that at least one CDR loop structure or part thereof is modified or replaced such that the solubility of the modified VLD is improved when compared with the unmodified VLD.

1 . A binding moiety comprising at least one monomeric V-like domain (VLD) derived from a non-antibody ligand, the at least one monomeric V-like domain being characterised in that at least one CDR loop structure or part thereof is modified or replaced such that the solubility of the modified VLD is improved when compared with the unmodified VLD. 
     
     
         2 . The binding moiety according to  claim 1  in which at least one CDR loop structure or part thereof is modified or replaced such that
 (i) the size of the CDR loop structure is increased when compared with the corresponding CDR loop structure in the unmodified VLD; and/or   (ii) the modification or replacement results in the formation of a disulphide bond within or between one or more of the CDR loop structures.   
     
     
         3 . A binding moiety comprising at least one monomeric V-like domain (VLD) derived from a non-antibody ligand, the at least one monomeric V-like domain being characterised in that at least one CDR loop structure or part thereof is modified or replaced such that
 (i) the size of the CDR loop structure is altered when compared with the corresponding CDR loop structure in the unmodified VLD; and/or   (ii) the modification or replacement results in the formation of a disulphide bond within or between one or more of the CDR loop structures.   
     
     
         4 . The binding moiety according to  claim 3  in which the size of the CDR loop structure is increased by at least two amino acid residues. 
     
     
         5 . The binding moiety according to  claim 3  in which the size of the CDR loop structure is increased by at least six amino acid residues. 
     
     
         6 . The binding moiety according to  claim 3  in which the size of the CDR loop structure is increased by at least nine amino acid residues. 
     
     
         7 . The binding moiety according to  claim 1  in which the binding affinity of the modified VLD is altered when compared with the unmodified VLD. 
     
     
         8 . The binding moiety according to  claim 7  in which the affinity of the modified VLD to at least one natural ligand of the unmodified VLD is reduced. 
     
     
         9 . The binding moiety according to  claim 1  in which the binding specificity of the modified VLD is different to that of the unmodified VLD. 
     
     
         10 . The binding moiety according to  claim 1  in which the non-antibody ligand is a T-cell surface protein. 
     
     
         11 . The binding moiety according to  claim 10  in which the non-antibody ligand is CTLA-4, CD28 or ICOS. 
     
     
         12 . The binding moiety according to  claim 11  in which the non-antibody ligand is CTLA-4. 
     
     
         13 . The binding moiety according to  claim 1  in which one or more of the CDR loop structures is replaced with a binding determinant derived from a non-antibody polypeptide. 
     
     
         14 . The binding moiety according to  claim 13  in which the binding determinant is derived from somatostatin or haemagglutinin. 
     
     
         15 . The binding moiety according to  claim 1  in which one or more of the CDR loop structures is replaced with one or more CDR loop structures derived from an antibody or antibodies. 
     
     
         16 . The binding moiety according to  claim 15  in which the antibody or antibodies are derived from a rat, mouse, human, camel, llama or shark. 
     
     
         17 . The binding moiety according to  claim 15  in which the antibody or antibodies are selected from the camel antibody cAB-Lys3 and the human anti-melanoma antibody V86. 
     
     
         18 . The binding moiety according to  claim 1  linked to a diagnostic reagent. 
     
     
         19 . The binding moiety according to  claim 18  in which the diagnostic reagent is selected from the group consisting of streptavidin, biotin, a radioisotope, dye marker or other imaging reagent. 
     
     
         20 . A multivalent reagent comprising two or more binding moieties as claimed in  claim 1 . 
     
     
         21 . The binding moiety or multivalent reagent according to  claim 1 , immobilised on a solid support or coupled to a biosensor surface. 
     
     
         22 . A polynucleotide encoding the binding moiety as claimed in  claim 1 . 
     
     
         23 . A vector comprising the polynucleotide according to  claim 22 . 
     
     
         24 . A host cell transformed with the vector as claimed in  claim 23 . 
     
     
         25 . The host cell according to  claim 24  in which the cell is a bacterial cell. 
     
     
         26 . A method of producing a binding moiety which comprises culturing the host cell as claimed in  claim 24  under conditions enabling expression of the binding moiety and optionally recovering the binding moiety. 
     
     
         27 . The method according to  claim 26  in which the binding moiety is unglycosylated. 
     
     
         28 . A pharmaceutical composition comprising the binding moiety as claimed in  claim 1  and a pharmaceutically acceptable carrier or diluent. 
     
     
         29 . A method of treating a pathological condition in a subject, which method comprises administering to the subject the binding moiety as claimed in  claim 1 . 
     
     
         30 . A method of selecting a binding moiety with an affinity for a target molecule which comprises screening a library of polynucleotides for expression of a binding moiety with an affinity for the target molecule, the polynucleotides encoding VLDs derived from one or more non-antibody ligands, wherein the polynucleotides have been subjected to mutagenesis which results in a modification or replacement in at least one CDR loop structure in at least one VLD and wherein the solubility of the isolated modified VLD is improved when compared with the isolated unmodified VLD. 
     
     
         31 . The method according to  claim 30  in which the screening process involves displaying the modified V-like domains as gene III protein fusions on the surface of bacteriophage particles. 
     
     
         32 . The method according to  claim 30  in which the screening process involves displaying the modified V-like domains in a ribosomal display selection system. 
     
     
         33 . (canceled)