Bifunctional polypeptides

Abstract

A bifunctional polypeptide comprising a specific binding partner for a peptide-MHC epitope, such as an antibody or T cell receptor, and an immune effector, such as an antibody or a cytokine, the immune effector part being linked to the N-terminus of the peptide-MHC binding part.

1 . A bifunctional molecule comprising a polypeptide binding partner specific for a given pMHC epitope, and an immune effector polypeptide, the N-terminus of the pMHC binding partner being linked to the C-terminus of the immune effector polypeptide, PROVIDED THAT the said polypeptide binding partner is not a T-cell receptor comprising the alpha chain SEQ ID No: 7 and the beta chain SEQ ID No: 9. 
     
     
         2 . The bifunctional molecule as claimed in  claim 1 , wherein the pMHC binding partner is a heterodimeric αβ TCR polypeptide pair, or a single chain αβ TCR polypeptide, and the N-terminus of the α or β chain of the heterodimeric TCR polypeptide pair, or the N-terminus of the scTCR polypeptide, is linked to a C-terminal amino acid of the immune effector polypeptide. 
     
     
         3 . The bifunctional molecule as claimed in  claim 2 , wherein the pMHC binding partner is a heterodimeric αβ TCR polypeptide pair wherein the α and β polypeptides each have TCR variable and constant regions, but lack TCR transmembrane and cytoplasmic regions. 
     
     
         4 . The bifunctional molecule as claimed in  claim 3 , wherein the constant regions of the α and β polypeptides are linked by a disulfide bond between cysteine residues substituted for Thr 48 of exon 1 of TRAC1 and Ser 57 of exon 1 of TRBC1 or TRBC2, or by the native disulfide bond between Cys4 of exon 2 of TRAC1 and Cys2 of exon 2 of TRBC1 or TRBC2. 
     
     
         5 . The bifunctional molecule as claimed in  claim 1 , wherein the pMHC binding partner is a single chain αβ TCR polypeptide. 
     
     
         6 . The bifunctional molecule as claimed in  claim 1 , wherein the immune effector polypeptide is an antibody which specifically binds to an antigen presented by a T-cell. 
     
     
         7 . The bifunctional molecule as claimed in  claim 6 , wherein the antibody is an scFv antibody. 
     
     
         8 . The bifunctional molecule as claimed in  claim 6 , wherein the antibody is an anti-CD3 antibody. 
     
     
         9 . The bifunctional molecule as claimed in  claim 8 , wherein the antibody is OKT3. 
     
     
         10 . The bifunctional molecule as claimed in  claim 8 , wherein the antibody is UCHT-1. 
     
     
         11 . The bifunctional molecule as claimed in  claim 8 , wherein the antibody is BMA031. 
     
     
         12 . The bifunctional molecule as claimed in  claim 8 , wherein the antibody is 12F6. 
     
     
         13 . The bifunctional molecule as claimed in  claim 1 , wherein effector polypeptide is a cytokine which modulates lymphocyte immunosuppressive or immunostimulatory activity. 
     
     
         14 . A bifunctional molecule, comprising
 a heterodimeric αβ T-Cell Receptor (αβ TCR) or a single chain T-Cell Receptor (scTCR), the scTCR comprising a TCR α or TCR β constant region, wherein the αβ TCR or the scTCR is specific for and binds to a given pMHC epitope,   and   an immune effector polypeptide comprising a single chain immunoglobulin which specifically binds to CD3,   wherein:   the N-terminus of the α chain or the β chain of the αβTCR, or the N-terminus of the scTCR, is linked to the C-terminus of the single chain immunoglobulin, and   the bifunctional molecule is capable of binding to the given pMHC epitope and CD3, each on a different cell, and thus simultaneously binding to two different cells.   
     
     
         15 . The bifunctional molecule of  claim 14 , wherein the single chain immunoglobulin comprises the CDR sequences of SEQ ID NO: 3.